CA1145208A - Semipermeable composite membrane - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A semipermeable composite membrane comprising a thin semipermeable film of a polymeric material deposited on one side of a microporous substrate, said polymeric material being prepared by crosslinking a soluble polymer containing at least 30 mole% of a recurring unit of the formula

Description

~ ~ ~ 5~ ~

SEMIP~EABLE COMPOSIT~ MæMBRANE
TECfr.NICAL FIELD
____ m is invention relates to a novel semipermeable composite membrane. More speci~ically, this in~ention pertains to a novel semipermeable composite membrane which has hi~h performances in selective permeabil~ty characterist~cs such as water fl~x and said reJection particularl~ suitable ~or reverse osmosis~ chemical res~stances such as oxidation resistance, acid resistance and alkali resistance, compactness, and thermal stabilit~7 and ~hich can be stored in the ~ry state; to a process for production thereo~; a~d to use of th~ aforesaid composite membra~e in reverse osmosis.
BACKGR
me semipermeable mem~r~e is a mem~rane which has selective permeability to speci~ied molecules. It is ~requently used to remove ~ery small amounts of cont~mi nated molecules dissolved or diff~lsed in a liquid or gas.
In recent yearsg reverse osmos~s has attract2d a great deal o~ interest ~or utilization in fields i~volvlng purification of liquids. This i8 0~ especial importance when utilizing this system in the purification o~ water and brackish water. Likewise, the process is ~.
also u~ed to remove impurities from liquids such aæ water or, i~ the fields o~ dialysis, blood. When utilizing reverse osmosis i~ the puri~ication of a brackish water, a pressure in excess o~ Whe osmotic pressure o~ ~he brackish water ~eed solution is applied to the solution : ~.
3 ~

~52~18 which is prepared from purified water by a semipermeable membrane. Pu~e water thereby diffuses through the membrane while the sodium chloride molecules or other impurities which may be present in the water are retained by ~he membrane.
me efficiency of the reverse osmosis method is greatly affected by the properties of -the semipermeable membrane used. Much effort has therefore been made to develop membranes havi~g high per ormance, and resulted in some speci~ic suggestions.
For example, U. S Patents Nos. 39133,132 and 3,133,137 disclose the early Loeb-type membranes made of cellulose diacetate. These membranes are asymmetric me~-branes which are characterized by a very thin, dense surface layer or skin that is supported upon an integrally a-ttached, much thicker supporting layer. These known mem~ranes based on cellulose diacetate have the defect o~ poor compaction, low reslstanoe to chemical an~ bio-logical degradation, a short useful like, inability of storage in the dry state, and insufficient flux and salt rejection characteristics.
In an attempt to overcome these defects of the Loeb~t~pe membranes, some membranes composed basically of syntlletic polymers have recently been suggested. For exampl~, U. S. Patent No. 3,951,815 dlscloses a composite semipe~meable membrane comprising a microporous substrate ancl an ultrathin film formed of a crosslinked, grafted polyethylenimide disposed on one surface of said micro-porous substrate that has been crosslinked with a di- or tri-functiQnal compound such as isophthalo~l chloride and grafted with a graft reactant such as acrylo~itrile or epichlorohydrin. U. S. Patent No. 4,005,012 describes a composite semipermeable membrane comprising an ultrathin fi~m formed by contacting an amine-modified polyepihalo-l~yc~in with a polyfunctional agent on a microporous sub-strate to form this film on one surface of the microporous subst~ate Also9 ~. S Patent No. 4,039,440 discloses a reverse osmosis membrane prepared in Si on a porous s~port by initial forma-tion of a layer of polyethylenimine on the support, followed by interfacial reaction with a poly~unctional reagent to produce a thin sur~ace coating which possesses salt barrier characteristics.
m e membrane composed basically of crosslinked polyethylemimine disclosed in U. S. P~tent No. 4,039,440 has a high salt rejection9 but has the defect of insu~-ficient water ~lux and low oxidation resistance ~e.g., low resistance to deterioration by the presence of chlorine in the feed saline or brackish water). As one me-~.hod of improvlng the oxidation resistance, U. S. Patent No. ~951,~15 suggests the gra~ting of acrylonitrile to the polyethylenimine. me acrylonitrile-grafted and cross-li~l~ed polyethylenimine shows some improvement in oxidation resistance, but as the membrane is operated continuo~sly for a long period of time, its degradation advances ~radually. Moreover, it suffers from the serious defect of lnaving a markedly reduced water flt~.
The membrane composed basically of tne amine-modi~ied polyepihalohydrin disclosed in U. S. Patent No~ 4,005~012 exhibits a high salt; reJection but its water flt~ is not sufficient. It has been strongly desired to develop membranes having a higher water flt~.
The characteristics reqtlired of semipermeable membranes are basically high permselectivity and a high ~1~/ In addition, they should have high resistance to compactionf superior resistance to chemical and biologi-cal degrada-tion, and suf~icient flexibility to endure shaping into modules in actual use such as a tu~e, spiral or hollow filament. ~le membranes so ~ar suggested lack one or more o~ these characteristics~ and are not entire-ly satislactory for use as semipermeable membranes~
Accordingly, it has been strongly desired in the art to develop membranes having a combination o~ the a~oresaid desired characteristics.

_ 4 _ DISCLOSURE OF ~.~ ~ NTION
It is an object of this invention to provide a semipermeable membrane which is free from the defects of conventional reverse osmosis membranesO
~nother object of this invention is to provide a semipermeable composite membrane having high pe~mselec-tiV.~Aty ancl flux, superior ~lexibility, high resistance to co~paction, high resistance to chemical and biological de~raclation and excellent storability in ~he dry state especially high permselectivi~y and/or superior resistance to oxidation.
Still another objec-t of this invention is to pro-vide a process for producing a semipermeable composite membrane having high permselectivity ancl flux, superior ~lexilibity, high resistance to compaction, high resis-t~lce to chemical and biological degradation, and storability in the dry state, A ~urther object of this invention is to provide a method for using the a~oresaid semipermeable composite membrane for the reverse osmotic desalination of saline or brackish water.
Other objects and advantages of this invention wi.l.:l become apparent from the ~ollowing description.
According to this invention, -there is provide~
a semi.permeable composite membrane comprising a thi.n semi-permeable film of a polymeric material deposited on one sic1e of a microporous substrate 9 said polymeric material being prepared by crosslinking a soluble polymer con-taining at least 30 mole% of a recurring unit of the ~o~mula (L)p _Q_ (I) Y-Z N
~2 wherein Q represents an organic radical con-taining 2 -to 30 carbon atoms and having a valence o~ (3+p) which optionally contains ~5 . 5 w.
a heteroatom selected from the group consisting of oxygen, sulfurg nitrogen and halogen atoms; Y
is bonded to the carbon atom in group Q and re--presents a direct bond, an alkylene group con-taining 1 to 3 carbon atoms or an unsubstituted or substituted phenylene group; Z represents "
-C- or -S02-; Rl represents a hydrogen a-tom~ or a monovalent organic radical containing 1 to 20 ca~bon atoms which may contain an amino group containing 1 to 2 active hydrogen atoms and a heteroatom selected from the group consisting of oxygen, nitrogen and halogen a-toms~ R2 represents an amino group containing 1 to 2 active hydrogen atoms or a monovalent organic radical containing 1 to 20 carbon atoms which contains an amino group containing 1 to 2 active hydrogen atoms and may con-tain a heteroatom selected from -the group co~sisting of oxygen~ nitrogen and halogen atoms, or Rl and R2, together with the ni-trogen atom -to which they are bonded, represent a 5- to 18-me~bered nitrogen-conta:ining heterocyclic ring which contains at least one amino group having one active hydrogen a-tom~ and when group Y re-presen-ts a direct bond and gro~p Z represents O O
,. ., --C-, Rl may represent C- bonded to that carbon atom of the group Q which is bonded, either directly or through 1 to 2 carbon atoms, to the carbon atom to which the group Y is bonded; p is 0, 1 or 2; and when p is 1 or 2, ~ represents the group -W-Z-~ l in which W represents a direct bond or an alkylene group containing 1 to 3 carbon atoms and Z9 ~ and R2 are as defined above, and having at least 002 milliequivalent~ per gram of said polymer9 of an amino group containing 1 to 2 active hydrogen atoms~ with a polyfunctional compound containing at least two functional groups capable of reac-ting with the 52(3 am~:ino group having 1 or 2 active hydrogen atoms.
The essential feature of tlle present invention co.nsists in the use of 9 as a starting material for the semipermeable membrane, a polymer containing at least 30 mole,6 of -the recurring unit of formula (I) in whicll a pen~n.t chain containing at least one amino group having 1 or 2 active hydrogen atoms (to be sometimes referred to l:lereinbelow as an "active amino group~') is bonded to the main chain of the pol~mer through amide or imide 10 li~ ages.
Thus, the polymer used in this invention retains h:igtl hydrophilicity because it contains mc~ny amide or im:l.de linkages as hydrophilic atomic groupings in the pendant chains. Moreover, since the polymer contains an active amino group in the pendant chain, crosslinl~ing of the polymer ~ith -the polyfunctional compound (to be referred to as a "crosslinking agent"~ havillg functional groups such as acid halide, sulfonyl halide, M-haloformyl, halofor~ate and aci~ anhydride groups easily cllan~es the ac-ti~e amino group to a linkage such as a carbonamid,e ~o~ -imide~ linkage~(-NC0-), sulfona~id?e linka~e (-MS02-~, urea linkage ~ C-N~) or urethane li-i~'.cage (_ M C-0~) which is stable -to oxidation, and thus gi~es a crosslinking site having superior chemical stabiliGy such as oxidation resistance, simultaneousl~
prov.iding superior basic performances such as hi~l water pe.r~eability and high salt rejection characteristics which ara re~uired of a reverse osmosis membrane.
~ ~3= ~
The essential feature of the present in~ention is the use of a polymer containing a recurring ~it of the fo-l~u].a (I,)p _Q_ (I) Y-Z-M~

wherein Q, Y, Z, Rl, R2, L and p are as defined above, ~52!)~

as a raw material for the semipermeable membrane~
In ~ormula (I), the organic radical having a valence of (3 + p) expressed by Q constitutes at least a part of the main chain o~ the aforesaid polymer~ and is a constituent component of a vinyl polymer such as an acrylic polymer, methacrylic polymer, styrene polymer, all~Jl polymer or diallyl polymer 9 or an aromatic polymer sucn as polyphenylene oxide or polyphenylsulfone. ~e organic radical Q may contain a heteroatom selected from the group consisting of oxygen, sulfur, nitrogen and haJogells, which may be present in various forms For exrample~ the oxygen may be present in such a form as an ether linkage (C-O-C), an oxo group (C=O), a hydroxyl group (-OH~, a sul~onyl group (-S02-), a sulfo group (-~03H) 9 a carboxyl group (-COOH) 9 or a lower alkyl ester group. m e nitrogen atom may be present in such a form as an amide linkage, a tertiary amino groupS a quaternary ammonium salt group, a nitro group, a cyano group, or an active amino group.
The halogen atom may be any o~ fluorine, chlorine, bromine ~nd iodine groups, of which chlorine and bromine atoms are preferred.
When the organic radical contains heteroatoms, the number of the heteroatoms is ~enerally up to 5~
pre~erably up to 2. The organic radical should contain 2 to 30 carbon atoms, pre~erably 2 to 20 carbon atoms, more pre~erably 2 to 15 carbon atoms.
It should be understood that the present inven-tion does not e~clude the presence o~ heteroatoms other tha~ oxygen, sulfur, nitrogen and halogens in the organic gro~p, and the presence of other heteroatoms such as alkall metal atoms is permissible.
me organic radical includes saturated linear aliphatic hydrocarbon radicals~ saturated alicyclic hydro-carbon radicals, and aromatic hydrocarbon radicals whichoptionally co~-tain the heteroatoms described hereinabove.
Thus, ~hen Q represents a sa~urated aliphatic ~5~

hyc~ocarbon group optionally containing a heteroatom, t~rpical examples o~ the recurring unit of ~ormula (I) are -those of the following formula tI-a):
,3 ,5 -C 4CH2 ~ C ~ . ~ (I-a) R4 Yl-Z-N~ :

~he:f.eiin R~ represents a hydrogen atom or an alkyl group con-taining 1 to 5 carbon atoms;
R4 and R5, independently from each other~
represent a hydrogen atom, an alkyl group conOtaining 1 to 5 carbon atoms 9 or the group W-Z N ~ 1 C Nq-l R
-P7-COORB, -0-RBl, or -0-R~2-X', in which R6 represents a h~tdrogen atom or an alkyl group containing 1 to 5 carbon atoms, ~ represents a direct bond or an alkylene group co:.-.taining 1 to 3 carbon atoms, R~ represents a hydrogen a-tom, an alkali metal, a quaternary ammonium salt radical or arl alkyl group containing 1 to 5 carbon atoms, R~l represents an alkyl group containi.ng 1 to 5 carbon atoms~ :
R~2 represen-ts an alkylene group containing 1 to 4 carbon atoms, and X' represents chlorine or bromine7 ~, Y, Z, Rl and R2 are as defined hereinabove;
an.d. a and b, independently from each other, are 0 or 1.
Typical examples o~ the recurring unit of ~ormula (I~ in which Q represen~s a saturated alicyclic hydrocarbon radical optionally containing the heteroatoms are ~hose of the following ~ormula (I-b):
~ CH2 -CEI ` CEI CEI2-S02-Cl~ CH2 (I-b) o "R2 .

~52l3 _ 9 _ wlle:rein represents a hydrogen atom or the group , Rl -C-/.N ~ and ' ~ R
Rl ancl R2 are as defined hereinabove.
Typical examples of the recurring unit o~
~ol~mula tI~ in which Q represents an aromatic hydrocarbon ra~ical optionally containing ~he heteroatoms include tllose o~ the ~ollowing formula (I-c):
(Gl)cl (G2)e~

-Rg ~ -U ~ - t ( I-c~
R
W-Z-N\

:LO wllerei.n Rg represents a clirect bond or the group (G3)f (G~)g 0-¢~S02~-0-c~3 U represents -0 , -~- or -~- 9 c~3 Gl and G2~ independently from each other, 15 represent a halogen atom, an alkyl group containi~g 1 to ~ carbon atoms, a haloalkyl group containing 1 to 3 carbon atoms or the group W Z N~'Rl c, d and e~ independently from each other, are O or l;
G3 and ~, independently ~rom each other, rep:resent a halogen atom, an aIkyl group containing 1 to 3 carbon atoms~ or a haloalkyl group containing 1 -to 3 carbon a'oms;

52~

f ancl g, inclependen-tly from each other, are ir..~.-tegers o:E O to 2 9 and W, Z, Rl and R2 are as defined hereinabove.
In the above formulae (I), (I-a~, (I b) and (I~c), -the l'all.~ylene group containing 1 -to 3 carbon atoms"
rep.resented by Y and W may be linear or branched9 and inclucles~ for example, methylene 7 ethylerle, n-propylene an.d. methylethylene groups. Of these9 the methylene group is preferred ~xamples of the substi-tuent on tne benzene ring in -the "substituted phenylene group" are a carbo.~yl group (-~OO.Hï), a sulfo group (-SO~I), the group CO~J-~ R 2 or the group _S02~ 1 in which P~l and R2 are as de~ined aboveor Rl and R2 rep~esent a h~dro~en atom, or a methyl, e-thyl, propyl or butyl group. Preferably, the substituted phel..ylene group is mono-substituted.
Generally, the group Y preferably represents a direct bond, a methylene group or a pllenylene group of ~he :for~ula - ~ 10 in which Rlo repres~ ts a hyc!rogen a-~or~, -COOI~ S03TI, -CON R 9 or -S02~- R il~ wl~.i.c~ R
antl R~ are as defined above. ~specially preferably, ~Q :i.s a ~lydrogen atom. ~len Q represents an aromatlc llyclrocarbon radical ~i.e., in the case of ~ormula (I-c)), Y ls especially pre~erably a direct bond or almethyle~e group.
In the abovg forrn~llae (I) (I~a), ~I-b) and (I-c), Z represents C or -S02-, g being especially p~e:~erred.
In the formulae (I), (I~a), (I-b) and (I-c), t~le group -N~ Rl is derivecl from an ~nine of the ormula H~ ~. , as will be stated hereinbelow. Accordingly, the group -M'' 1 can represent a monovalent.substituted amino ~roup re~ulting ~rom the remo~al of o~e acti~e .~.

~52~

hydrogen atom from one amino group o~ a polyamino compound containing at least two active amino groupsO ~hus9 it can be said that Rl and R2 in the above formulae are the remainder of the aforesaid polyamino compound left after the remo~al of the nitrogen atom to be bonded to the group Z and one active hydrogen atom bonded to this nitrogen atomO Specifically9 ~ represents a hydrogen atom or a monovalent organic radical containing 1 -to 20 carbon atoms which may contain an amino group containing 1 to 2 active hydrogen atoms and a heteroatom selected from oxygen7 nitrogen and halogen atoms9 and R2 represents an amino group containing 1 to 2 active hydrogen atoms9 or a monovalent organic radical containing 1 to 20 carbon atoms which contains an amino group containing ]. to 2 active hydrogen atoms and may contain a heteroatom selected from oxygen., nitrogen and halogen atoms1 or Rl and R29 to-gether wi-th -the nitrogen atom to which they are bonded9 may represent a 5- to 1~ membered nitrogen-containing heterocyclic ring which contains at least one amino group having one active hydrogenO More speci~ically9 Rl represents a hydrogen atom9 an alkyl9 cycloalkyl~ aryl, aralkyl or heterocyclic r~dical cont~:Lning 1 to 20 carbon atoms9 preferably 1 to 12 carbon atoms9 and optionally containing 1 to 8, preerably 1 to 59 heteroatoms or he-teroatom-containing atomic grou-pings selected from the group consisting o~' halogen a-toms (eOg~9 chlorine and bromine), hydroxyl groups9 cyano groups9 carbo~yl groups9 alkoxycarbonyl groups with the alkyl moiety having 1 to 5 carbon atoms (eOgO9 -COOCE39 -COOC2H5 and -COOC3H7)9 primary amino groups (-NH~)~ e-ther linkages (---O-~)9 imino linkages (-~H-) and tertiary amino linkages ( N-);
and R2 represents a primary amino group9 a secondary amino group mono-substituted by an alkyl group contain-ing 1 to 5 carbon atOms9 or an alkyl9 cycloalkyl9 aryl, aralkyl or heterocyclic radical containing 1 to 209 preferably 1 to 129 carbon atoms which contains 1 to 10~
preferably 1 to 69 primary amino groups or imino li~ages and may contain 1 -to 99 pret'erably 1 to 69 heteroatoms :.

~SZ~)8 or lleteroatom-containing atomic groupings selected from -the gro~p consisting o~ halogen atoms9 hydroxyl groups7 cyano groups, carboxyl groups, alkoxycarbonyl groups con-taining 1 to 5 carbon atoms, ether linkages and ter-tiary amino linkages (-N-)9 or Rl and R2, toge-ther w.it,h the nitrogen atom to which they are bonded, may represent a 5- to 18- membered nitrogen-~ontaining heterocyclic ring optionally containing 1 to 4 nitrogen or o~gen atoms as heteroatoms 9 such as C ~ CH~
~N~ -N~ N~_,Nff and 3 ' ~O 0~~, -N ~-~0 ~0~

Typical examples o~ the groups R~ ancl R2 are gi.venbelow. It should be understood that these exam,ples are merely illustrate, and are not intended ln any wa~
to l:i.mit the scope of the present invention.
(1) ~xamples of R
CT-I3, -C2~I5~ C
CI'~2~'I2CN~ ~CII2cTI2olI~ -C~I2CII~I20~ C~I2C~ICH~
OM OH
G'2CTI2CC~3~ 2CI~2cooc~I5~ CH2cooc~-I7~ -~ CI-I2N~IC.H~ -CH20~3 7 -CH~CM20CH3~ and -CH2~I=CH2-

(2) ~xamples of R2 NH2, -NEICH~, t~ N ~C~I2~ N~I2~ R24~NII-CH2 c~C~3)2 (R24 1 5 -~lï2~-I ~I2, -~C~I2-~I2-M~ ~l H(Xl 1 ), ~CI.i.2~ -I2 (X2-1 - 10) ~ -C~I2-C~I2-N-C~I2-CH2-1\
CH2-~-I2 ~2 ~2 N CI~2-~I2 ~ N-C~-I2-CH2-I~I2, ~I-I2-C~I2~ C~ C~I2-~H2 ~s~

R25N~ 2~x3 (R25=Cl-C5 alkyl9 X3= 2 - lO) C~ CH2-0-CI-I2 CI'I2~ 2 ~ CH2-Cli2- 'cM2-o-ci~2-cT~`I2-~H
IIQ- ~H2 -CH-CI-I2 -1~1.H~CIi2~CTI2-l`lIl~ CH2CH2-CE~2~ 2--I~--CEi 2--~I 2 W M Cr~I2--CIi2--GH2--I~I2 .
CT12--C~12--Cl CI~2--C i2--~TLI2 (XL~ = an integer of 1 - 20;
-C3~2-C~2-~,~, ~l``lIi2, -O-r~T;-l2~ -CM2~\

2~i 2 ~-O- C ~ 2 {~3- 0 ~Q~ 2 C~-~2

3 ,\~ and3 ~) -CC~H~I2 ' ~C' N~2 N CH~3 NH2 CM2-P~-I2 ~r..--I2 _~ , _~ , ~-0~

N:H-CH
-(~ 9 ~)-CII2~-~I~, and ¦ 0 l (3) Examples of the.heterocyclic ring :Eo:rqned b~r ~l and R2 ~ J ~\N~T ~ H, 3 2 ~C

3~ CH2 )~CN~, ~ O O -~
c~l2ct~2l~lcH~, O\ O

C ~ 2 ~ C rI C.H 2 ~ r~i The term "all~yl group", used in the present spccification and the appended claims 9 denotes a l:i.near 52~8 or hr~lched saturated mon~valen-t aliphatic hydrocarbon group, and includes, for example, methyl 9 ethyl; n- or iso~propyl, n- 9 iso-, sec- or tert-butyl~ n-pentyl~
iso-~a~.myl, n-llexyl, and n~octyl.
The term "cycloalkyl group", as used herein, denotes a monovalent saturated alicyclic hydrocarbon group such as cyclopentyl, cyclohexyl, cycloheptyl or cyclooctyl.
rne term "aryl" clenotes a monocyclic or poly-cyclic aromatic hydrocarbon group suc~ as phenyl 9 tolyl 9 xylyl or naphthyl rne term "aralkyl group", as used herein~
denotes an aryl-subs-ti-~uted lower alkyl group in which the aryl and alkyl have the same meanings as described above. Typical examples are benzyl and phenethyl Ihe term "heterocycllc group", as used herein~
denotes a monovalent cyclic group preferably w.it.h 5 or 6 memberS~ in wl~ic~l at least one, preferably 1 to 2, ring mem~ers are heteroatoms such as oxygen or nitrogen, and m e remainder of the ring members consists of carbon ato.¢ns. Specific examples are as follows:
~1~ ~I3 ~ I3 The term "lower", used in the present specifica-tiol.~. and appended claims to ~ualif.y groups or compounds, denotes that the groups or compounds so quali~ied have no-~ more than 4, preferably not more than 3, carbon at.oms.
The polyamino compound which will provide Rl and R2 co.ntains at least two active amino groups 9 i.e. primary aml~no groups ~-NH2) or secondary amino groups (~ , also called imino group), which can react w.ith the polyfunc~
tional compound.
The polyamino co~pound used in this invention is not particularly limited in its type so long as it 52~3 coni;ains at leas-t two o~ primary amino groups, secondary amirlo groups,or bo-th per molecule. It may range ~rom a low~molecular~-weight compound to a high-molecular-weight compound9 and may be linear or branched. I-t may further eon-tain an aromatic r-ng, heterocyclic ring or alicyclic ring. The structural moie-ty of t7ne polyarnino compound e~cluding the reac-tive arnino groups may contain hete~o atoms such as oxygen and halogen in addition to carbon and hy~rogen atoms. ~le active amino groups can be present at -t1le ends or side chains of the molecular chain, and seconclary anino groups may be incorporated in -the mole-cular chain, The number of the primary and secondary amino groups that can be present in the polyamino compo~d may be at least two, and no strict upper limit is set up.
IIowever, from the standpoint of the characteristlcs, es~ecially salt rejection, of -the resulting membrane, the polyamino compound suitably has ail "amino equivalei1t"
o~ ge11erally lO to 40 mulliequivalents tto be abbreviatec1 "meq") per gram of the polyamino compound, preferably 15 -to 35 rneq/g, especially preferably 20 -to 30 meq/g.
~ e -term ~'amino equivalent", as used in the present speci~lcationl denotes the sum of the equivalents o~ prirnary a~ld secondary amino groups containecl per grarn of ~e polyamino cornpouncl ~le s~ o~ the equival~nts o~ e primary and seconclary amino groups can be deter-mined generally by a known determination method (such as ~he perchloric acid-glacial acetie acid method, or the azomethine method).
Desirably, the two or more aetive amino groups present in the polyamino compound should not be spaced from one another too far. It is advantageous tha-t the nu1r!lber of carbon a-toms whieh constitute the chain eonnec-ting two adjacent active amino groups in the same molecule is generally not more than 15, preferably not more than lO, and more preferably 2 to 5.
The molecular weight o~ the polyamino compound ~5~

is nie-ther critical, and may range from a low molecular weig~-t to a high molecular w~ight. From the stanclpoint o~ e characteristics 9 especially oxidation resistance, of t,h,e resulting membrane, suitable polyamino compounds I~ave a molecular weight of generally not more than 1000, preferably 60 to 500, e~pecially pre~era~ly 100 to 300.
Polyamino compounds that can be used in this invention can be selected ~rom any known polyamino compounds wk.ich have the aforesaid characteristics.
Typical examples are given below. We do not inte~d Ilowever to limit the scope o the invention by the follow-ing exempli~ication.
(1) Aliphatic polyamines H2N ~H2~ N-( N~.t2 24 I~H CH2-C ~t3)2 (~2~- Cl-C5 alkyl), EI2N_cH2_CII2_N~I2~'t~2N ~ tI2-CH2~N~I ~ tI (x~ 20)~

I12N 4CH2~ NI-I2 (x2=1-10), H2N-CE12 CI-I2-N-CH2-CM2-N~I2, 2N-C~t2-CH2-N-CI-I2-C~I2 N,-CH2 2 2' CE12-CH2 Nt~2 C~12-CH2 NII2 25 (C~I2 ~ ~-I2 (R25=Cl-c5 alkyl; x3-2 10) NC-CH2-~2~N~ C~I2-CH2-I~t~ ~ H, NC-CI-I2~C~I2-NH ~ CX2-CH2~ 't~ C~'I2-C~2-GM
H2N-CH2-C~I2~0-CH2-cIl2-NE~
H2M-cTrI2-CH2-CH2-O-cII2-CH2 C~
HO-CH2-CT~-C.tI2-NlI ~I2-C.I2 NE~ H~
OH
HO-CI-t2-~T`I-CH2-N~I~I2-CH2 ~ Ct-I2-CEI-CI~ OH
OH OH
I~I~N ~C.12 C~I2 ~ 9 ~S2~3 Cl-CH2-CH2~ GII2-Ci-I2- ~ H, 2N ~2 CH2 i\,~-~rI2-C~T2- M-CI-~2-C~
CH2-CH2-Cl C ~2-C -I2-N~I2 (X4-X~ integer of l - 20, xg 9 xlo=an integer of l - lO) (2) Alicyclic polyamines HN I~17 IlN ~ NH ~R26=~I or CJ:-I3, C2.5, (P~26 )x xll=an integer of 1 ~ ~)~ H2I~i-CII2-Cii2-~

NH 2 2 2 ~_J ~ 2 2 ~ H2N-~_N~I2 7 ~IN ~ {
~ 0~0~
H2N-CH2~ ~ , II~ ~I , CH2-N112 " ~

2 ~ NH2, H,jN ~ CH ~ 2 ~T;I
H2N ~ 0 ~ N~I2. 3 > ~ and ~ M~2 ClI3 3 ~ -C-~-I2.

I~2N 3 (3) Aromatic polyamines CH ~
H2N- ~ , 2 ~ 2 2 ~I2M N~I2 ~ C.I-I3, '~-~ , H2N~

2~ ~ ~CH2 ~ ~ 2 and ~12N~~NJ ~ N~2 ~`5~

`` 18 ~

(4) Hydrazines ~NH~, H2~o~HCH~7 CH30~Ho~HOCH3 These polyamino compounds can be used either alone or as a mixture of two or more.
Polyamino compounds that can be used advantage-ously in this invention are aliphatic or alicycl.ic poly-am~ino compounds expressed by the following formula (II-a), b), (II-c), (II-d) or (II-e).

Al~ A2~ A3 (II-a~
A4-~ cH2_C~I2-N ~ A5 (II-b) A~
H~7~_J 7 8 (II-c) Ill~ ~ -Ag ~ ~ (II-d) or HM A~ (II-e) t ~12 wl~erein Al ~ld A~, independently from each other, represent a hydrogen atol.n or a lower a:Lk~yl group9 A2 represents an alkylene group h.aving 2 to 10 carbon atoms which may contain an ether li~age ? AL~ and A5, independently from each other, represent a hydrogen atom or a lower alkyl group optionally substituted wi~ a cyano, ~ydro~yl or lo~er alkoxycarbonyl group 9 A~
represents a hydrogen atom or a group of the for~ula -CH2-CM2W~ A~9 ~ represents a lower alkylene group; A8 represents a hydrogen atom or a lower alkyl group optionally substituted Wi~l a cyano~ hydroxyl or lower alkox~carbonyl group; A9 represents a lower alkylene group 9 at least one o~ Alo, All and ~12 r p lower alkyl group, and ~le remainder represent 3 a hydrogen a-tom9 and i is an integer of 2 to 60 ~ 19 -Of the polyimino compounds of formulae (II-a)~
(II-b) 9 ~ c), (II d) and (II-e), those of formulae (Il b) and (II e) are especially pre~erred.
Typical examples of the polyimino compo~nds of ~ormulae (II-a) and (II~e~ include the ~ollowi~g, 2 2C~I2i~I27 ~12M~I2ClI2clI2~I2, H2N(CfI2~ ~-I2, CH ~ IClI2C~lCH~;, CLI3NTICI-I2C~I2C~I2I``rrI~
CH~ Ic~I2H~I2cIl2c~I2~iIcH3~ C2II5NH~2C 2 2 5' C2H5~-ICIf2CH2C~H2MHC~H5, C2I-I5NHCH2~12~ 2 2 2 5 Ho~I2cH2N~..IcI~2cII2c~-I2NHc~I2cH2o~I, I2CH2I\~IC112CH2C~t2C~.I2~ 2c-~
E12NCH2CH2-O-cH2c~I2l`~H2 . 3 I CII2CH2 OCEI2CH2~ICH3, HocH2cH2N~IcII2c~I2I~IcI
e ~II~b ?
H2I`T ~CH2C-I2~-I~ II2N ~CH2CH2~ H
C~I3~r-I ~CI[2C,I-I~ CII3~ C,7I3N.~I ~CI?.2CH2Nr!l~ C~I3, CH3i~I ~ CI-I2~'T~.T,~ CH3, ~I3N~ICT~-I2CI12M~I2C~T2N~ICII3, 2~ 2 ~2~ 4~ 2~-CH2C.T.-I2~-CII2C~I2~I~
CH CH ~I2 MOCH2CH2MTlI ~CH2C.TrI2I~I~ CT~ I2C~I20II, EIoC~ I2CTjI2M~I 4 CH2CT`-I2~ C~ H2II -r~ r ~ 2CH2N~2 ~ `T-cH2cI'I2~ I3 ~_) 2CH2N~C~I5~ II ~ N-CH2CH2~..... -IcH2c~20~I~
lI~f \M-CH2CH2MXCII2CH2c~, N~ cH2 ~ N~-L~ ~12C112 ~ I, _ 20 --II~T~ l CII CM {~ TO-C~I CHCrI ~MH

, 3 ~ 2 .CN~ TTl~
~hen in formula (I), -the group YOrepresents a clirect boOd and the group Z represents C ~ Rl may represent -C- bonded to ~hat carbon atom o~ the group Q
wl1i.ch is bonded, eit;her directly or through l or 2 carbon a-to!ns, to the carbon atom to which the group Y is bonde~.
In ~l!.i.s case, the recurring unit (I) is typically expressed by -the following formula tI-d):
Rll R,12 -C ~CH2~1 C-d) O=C C=O
N
R
wherein Rll and R12, independently from each other,rep~esent a hydrogen a-tom or a met;hyl group;
Rl3 represents a primary amino group, a secondary amino group mono-sub~tituted by an alkyl group containing .
l to 5 carbon atoms, or a.~alkyl, cycloalkyl, aryl1 aralkyl or heterocyclic group containing l to 20 carbon atoms which contains 1 to lO primar~ amino groups or imino li.nkages and may contain l to 9 hetèroatoms or heteroatom-contain-ing atonic groupings selected from the group consisting of halogen atoms, hydroxyl groups, cyano groups, carboxyl groups, alkoxycarbonyl g~oups with the alk~l moiety containing l to 5 Garbon atoms, ether linkage~s and tertiary amino linkage (-~-=; and h is 0 or 1. ~

~- 21 ~
Specific examples of the group R13 are as follows:
CH
~CH2) 3-N-~CH2~3~ 2 R24-~;1H-CH2-C-(cH3) 2 (R24 Cl 5 ~

2 2 29 ~CH2 -CH2-NH)x H (x~ 20) 9 -~CH2~X~ NH2 (x2 = 1 - 10) 9 -CH2-CH2- 1 -CH2cH2~EI2 CH2-cH2-NH2 -cH2-cH2-N-cH2-`cH2 N-CH2-CH2-NH2 , CH2 -CEI2- ~H2 CH2 ~CH2`-NH2 (CH2)x3 (R25 = C1--Cs alkyl; x3 = 2-10) - CH2-CH2-0-CH2-''CH2-N~2 9 - CH2-cH2-cH2-o - cH2cH2 -cH2 -~H2 9 -CH2--cH2-N-cH2-cE2---N-CH2-CH2-NEI2 ~
CH2--`CH2 Cl C~2 CH2 ~H2 ~.

- CH 2-CH 2 ~~J~ ~ I2 ' ~ 2 -CH2~`CH2-NH2CH2-~}NH2 9 .~_C~-~IH2, ~}0~ H

H3C~? H3CX~> ~ 3 ~H`

H3 ~H2 CH3 H2~-~ 2, ~0 ~;IH2 ~H-CH3 ~CH2 ~- NH2 and '~N0lN~I2 O

. , ~.- , . . . ~ . .

~5;~
~ ~2 Especially preferred among the recurring uni-ts o~ :~ormula (I-a) are tllose of the ~ollowing formu~a (I-a~
R301 ~501 _~CTI2~ 2~ aDl ) P~401 Yl--Z-N~R101 where:i.n R~o1 represents a hydrogen atom or a methyl gro~P;
R401 and R501 9 independen-tly ~rom gach o-ther represent a hyclrogen atom, a me^thyl group, ~C M Rll OOR801, -OR~ol, -O~I~C~I2 in whi.ch X :is chlorine or bromine, or -~H2-COOR~ol;
Yl representa a direct bond, a met~lylene group or a pllenylene group of the formula _ ~ ~10 in whlch Rlo r:epresenta a hydrogen atom, -COOI-l, -S03M, -COl`~ 01 9 or ~2~ ~ R ; 201 Z represents -C- or -SO"-9 Rlo1 represents a hydro~en atom,an alkyl, cycloalkyl, aryl~ aralkyl or heterocyclic group containing 1 -to 12 carbon atoms which may contain 1 to 8 heteroatoms or he-~eroatom-~ontaining atomic groupings selected from th~ group co~sisting of halogen atoms9 hydroxyl groups, cyano groups, carboxyl groups, alkoxycarbonyl groups Wittl tlle al~yl moiety containing 1 to 5 carbon a~oms~
primary amino groups (-NH2), ether linkages (-O-) J
im:ino linkages (~ ), and tertiary amino linkages ~5 (~`J-)~
R201 represents a primary ~ino group 7 a secondar ~y amillO group monosubstituted by an alkyl group containing 1 to 5 carbon atoms, or an alkyl, cycloalkyl, aryl~
aral~yl or heterocyclic group containing 1 to 12 carbon .

~52~
~ 2~ ~
atoiQs which contains 1 ~o 6 primary amino group~ or imino li'.l.~ages and may con-tain 1. to 6 heteroa-torns or hetero-atol,.n.-containiilg atomic groupings selected from the group corlsisting of halogen atoms, hydroxyl groups~ cyano groups, carboxyl groups, alko~ycarbonyl groups wi.th the al?~yl rlloiety containing 1 to 5 carbon atoms, ether ages and tertiary amino linkages (~
Rlol and R201, together with the nitrogen atom to which they are bonded, may represent a 5~ to 6-membered nitro~en~containing h~-teroc-yclic ring which contain~ at least one ami~o ~roup having ~ne active h~dro~en atom;
R~ol represents a hydrogen atom or an alkyl group containing 1 to 3 carbon atoms; and a and b, indepenclently from each other, are 0 or 1. In particular, the group N~ ~101 in formula (I~a~l) is any of one of the following --~J-A2~ A3 (II-a-l) ~AL~ (II-b-l) (C~12C112N~A5 ~f ~ r-~ (II-c-l) ~ A7-r~NII

-N ~ -Ag~ d-l) A~o All -N ~ .. -1 (II-e-l) In the a~ove formulae, Al througn Al~ are the same as -those de~ined in formulae (II-a) to (II-e) given hereillabove .
Thus, typical examples of tlle recurring ~mit of fo~nula (I-a-l) include the following.

s~
-- 24; _ C~ r~3 -CH2C~ CII2~C- ~ -CEI-- CEI-O-C~ 101 o ~ R COO:~O=C-l~T~ R10 CH C-~ 101 C~2~-N 101 -CH2C~ 2 ~ R201 -CE~2-C- 201 O=C-N 101 ~OOR
~ R201 O R ..
,~C-N 101 C~R~301 C~I2 C~ ~ R201 ~ _CEI2C~
Cr~~ ~101 O=C-~i' 101 a R201 ~201 COO~I

O=C-N ~ lo=C_~ 101 O-C-N 101 o--C-uN
R20l 201 COOH C~I3 COOH
_~I2CI~I--C~ CH- R ;CH2C~ R
COOR O-C-N~ ~01 COOR801 O=C-N 10 '

5~8 -- 2~ --COOI-[ COOlI
CI12(~1 CII C7II Rlol ~ --C~I2CH--CH - Cn~
OR~301 0~ O O=C~N 101 C~) c,~3 -CH2_C- _ R ~ -C~I2CIJ-CX2-S02~ 101CH -SO ~ 101 O=C-N-- 101 ~SO N ~101 Crl~;
CH2 C CII.~-C-R ~O~M 101 201 ~ R201 ~3 C,~I3 -CH-CI-I2-CII- R, -C-CI-I2~C-COOH O=C-N~ 101CHo I Ii ~ R101 ~201 P'201 Of the ~ecurriIlg UXlitS o:E formula (I--c), pre-:Eerred are those of the Iollowing fo~mulae _0~ S02~ o~~U~3~ ( I-c-l ) Wl--~
~201 and - ~6 -R (I-c-2) Wl-Z N

~Iherein Wl represents a hydrogen atom or a me~ ylene group; G5 represents a hydrogen atom, a halogen atom, a methyl group, a t.rifluoromethyl group, or the group N- ~1019 and U, Z 3 Rlol and R2~1 a R
hereinabove .
r~ypical ex~nples o~ the recurring unit of ~ormula (I-c-l) or (I-c-2) are as ollows:
C~
-O~-S02~-0~-C-~

O C l~--Rlol ~201 -~ -S2~ -~- CI~2~3 o=~ r~ lol R20l -o~ so2~ o~ 4~
O-C N ~ R101 R
CH
_o~ so2~ o~?-s~ 1~

O=S-M~ 101 0 ~201 _o~_so2~3-O~~cH2 ~3 S02-M ~101 --O-~S02~ 0--~~0~

S0 N ~101 CH~ &H2X
~r- 4~o_.
\:~ R101 ~/\ R101 2~1 0 `201 o R (X = Br Cl) ~H~C-~\ 101 - ~ o 201 \CH C-N 101 2,. `R

The molecular weights of po~lymers containing these recurring units are not particularly limited, but usually on the order of several thousand to -ten times thereof~ and their degrees of polymeri.zation are about 20 to about 500, preferably 50 to 300O
Among the recurring units of formula (I)~ recur~
ing units o~ formula (I-a-l) derived from vinyl monomers are especially preferredO
~ he soluble polymer used in this invention may contain at least ~0 mole%~ preferably at least 50 mole%9 more preferabl~ a-t least 70 mole~0~ o~ a recurring unit of formula (I) including formulae (I-a) 9 (I-b) 9 (I-c), (I~d), (I-a~ b~ and (I-b-2)o ~hose which are substantially linear are suitableO In -the present invention~ polymers substantially composed only of the recurring uni-ts of formula (I), and copol.ymers composed of the recurring unit of` formula (I) and another monomeric unit copolymerizable with the unit of formula (I) can be used so long as they contain the recurring unit of formula (I) in the molar proportions specified aboveO ~he other monomeric units co-polymerizable with the recurring unit of formula (I) in the soluble polymer are described hereinbelowO
Polymers containing -the recurring unit of formula ~ ~ ~ 5~ ~
. 28 (I.-c) including formulae (I-c_l) and (I-.c-2) are desirably composed substantially only of the recurring unit of formula (I~c)o In the present invention9 the molecular chain of polymer con-tains a-t least 30 mole% of the unit of for.mula (I)o Preferably, the units of formula (I) are distributed as uniformly clS possible in the polymer chainO
The recurring unit of formula (I) can be present in the polymer in such a proportion that the amount of "amino groups containing 1 to 2 ~c~tive hydrogens" present in the group -N ~ 1 in the pendant chain (io eO ~ active amino groups) is at least 002 milliequivalent (meqO), preferably 005 to 20 meqOg more preferably 1 -to 20 me~0 9 per gr~m of the polymerO
~ery desirably, the polymer used in this invention should be e. soluble polymer which dissolves to some extent in wate~ or water-miscible polar organic solvents in an amo~n~t of at least 0~1 g9 preferably at least 005 g, more . prefere~bly at leas-t loO g9 at 25C per 100 g of wa~ter or the org~nic solventO
~ he dissolving of the polymer means not only the complete dissolving of the polymer in molecular form in a given solvent to form a true solution, bu-t also the dis-persion of the polymer in the form of a colloid., la-tex or emulsion which can be coa-ted on a microporous substmte (to be described hereinbelow) to form a coating thereonO
~ ypical exe~mples of the water-miscible polar or~anic solvent used to determine the solubility of the polymer include lower alcohols such as methanol, ethanol9 n-propanol e~nd iso-propanol, formic acid, dimethylform-amide (DMF)~ dimethylsulfoxide (DMS0), tetramethylene-sulfone, and N-methylpyrrolidone (NMP)o ~'hese organic solvents may cont~in up to abou-t 10% by weight of waterO
~he polymer used in this invention is not strictly limited in i-ts molecular weig~rt (degree of polymerizcation) if i-t has the solubility specified above and film~-forming abilityO Generally, the polymer desirably has an inherent viscosity ln~relO
~ inherent conc ~ polymer) ~5 in formic acid at 30C, of at least 0,l dl/g, preferably 0~1.5 to 5.0 dl/g~ more preferably 0.2 to 2.0 cll/g (0.5 0 polyL~er solution) me polymer used in this invention usually ha a nu~ber average molecular weight in the range o~
abol.lt 500 to about. l,000,000, preferably about 2jO00 to about 200,000.
The soluble polymer used in this invention can be easily formed by reacting a polymer (to be re~erred -to as an "intermediate polymer") containing at least 30 moleS~ of a recurring unit of the ~ormula (W-~-T~p --Q ~ (V) y_z _rr wherein T represen-ts a l-alogen atom or an alkoxy, ar~loxy, alkenyloxy or aralkyloxy group conta.ining l to 20 carbon atoms, or toge-ther wi-th Y-Z-Q, represen-ts a 5- or 6~membered cyclic acid a1~lydride group or cyclic imide group, and Q, ~, Y, Z and p are as defilled llereinabove ~
wil.~.l an amine of the ollowing fo;rmula ~ P~l T~ (VI) '2 wllerein Rl and P~2 are as defined.
The functional group -Y-Z-T in the inte~nediate pol~r.,ner containing the recurring ~mit o formula ~V) may be :i.atroduced into the polymer after its forma-tio1n. It is convenient generally, however, to prepare the lnter-mediate polymer by using a monomer having such a ~unctional group ~rom the viewpoint of tlle ease o controlling the content or position of the functional group.
r~hus, known polymers can be used as the inter-med:i.a-te polymer containing the recurring ~mit of formula 30 ~
(V), or such a polymer can be easily prod.uced by l~nown meti~ods.
A first metllod for preparing the inter~ediate pol~rner containing the recurring unit of formula (V) t~rpically comprises subjecting to addition polymeriza--tion in a ma~er known ~ at least one of monomers of the followi-ng formulae (VII) wllich will provide the recurring units of formula (I-a) or (I-d):

~ C=C (VII~
R32 ~ \ R34 wherein R31 represents a hydrogen atom or an alkyl grouP containing 1 to 5 carbon atoms;
R32 and R33, independently from each other, represent a hydrogen atom, an alkyl group contain.ing 1 t8 5 ca.rbon atoms, the group -W-Z-Tl, the group C'-NH-R6 or the group -~ -COOR8, R~ represents the group -oY~ZoTl o g wi~h R~2~ ~epre~ents -the group _y2~c-o C Y2- ' group -Y2-C NEI-C-Y2-) ~0 Tl represents a halogen atom, or an alkoxy, aryloxy) aralkyloxy or alkenyloxy group containing 1 to 2 car~on atoms 9 Y2 represents a direct bond or an alkylene group contailling 1 to 2 carbon atoms, and W, Y, Z, R6, ~ and R~ are as defined hereinabove, arl~
~I2C CM2 R35~ C,-R35 (VIII~
~ D~
~here.in R35 and R36, independently from each other, represent a hydrogen atom or a methyl group; and D represents -0- or ~ 9 or cornprises copolymerizing at least one of these monomers wit!~ another monomer copolymerizable therewith iI?. a manner lmo~rr~ se.
Specific examples of monomers of fo~mulae (VII) ancl (YIII~ are given below.
(i~ Alpha, beta-unsaturated dicarboxylic acid anhydrides such as maleic anhydride, itaconic a~ydride, acr~lic ~ydride, methacrylic ~lydride and vinylphthalic anhydride.
(ii) Alpha, beta-unsaturated mono- or di-carboxylic acids such as acrylic acid, methacrylic acid~
malci.c acid 9 fumaric acid and vinylbenzoic acid.
(iii) Cl-C6 alkyl esters and C6-C15 aryl esters of alpha, beta-unsatura-ted mono- or di~carboxylic acids suc,-~ as ethyl acrylate, ethyl methacrylate, dimet~yl f~arate, methyl maleate, dimethyl maleate, phenyl acx~late, methyl vinylbenzoate and ethyl vinylbenzoate.
(iv) ~lpha,beta-unsaturated sulfonic acids and salts thereof,such as allylsulfonic acid, sodi~ allyl-su~ onate, methallylsul~onic acid, sodium methallylsulfo-na te 9 styrene-sulfonic acid, and sodium styrenesulfonate, Of -these vinyl monomers, the unsa-turat~d carboxylic acid anhydrides (i) and the esters of ~sa-tu-rated carboxylic acids (iii) are preferred. Polymers or co~olymers derived ~rom maleic anhydride, itaconic an-hyclride, ethyl acrylate, methyl methacrylate and acrylic a~l?ydride are especially preferred.
It is possible to convert ~he polymer (?:~ the virlyl monomer after polymerization in-to the functional group -Y~Z-T, and use it for reactiorl with an amine. For example, acrylic acid or methacrylic acid, after polymeri-zati.on~ can be converted into a polymer having a cyclic acid ~ydride group partly with a structure similar to a cyclic polymer of acrylic anhydride or met;hacrylic ~ yclride by causing a sui-table dehyc~ating agent to act ~5;2 ~2 or.l t.!.e resul-ting ~olymer. Alterna-tively,by the ac-tion of an acid halicle, the polymer o~ -the vinyl monomer can be converted to a polymer simîlar to a polymer prepare~ from acri,:Loyl chloride or methacryloyl chloride as a starting material.
Likewise, as require~. a monomer having a sulfo grovp (-S03H) or a sul~onate group (-S03Mg in ~liCh M is an al}.~ali metal), after polymerization, may be converted to a polymer having a sulfonyl halide group (-S02X) or sulfonyl ester group, and then reacted with an amine.
Polyacrylonitrile, for example, can be converted by hydrolysis to polyacrylic acid although acryloni.trile is not included with the a~oresaid group of vinyl monomers.
Thus, it should be understood that those monomers w~ich are not included within the aforesaid group of monomers but ~ ich afford polymers equivalent to the polymers of the above-exemplified monomers by a polymer reaction ...
C~.l also be used.
m e o-ther monomer copolymerizable with t:he vinyl monojner of formula (VII) or (VIII) above may be selected frolm a wide range of radical polyme:rizable monomers which copolymerize with -the vinyl monomer in the presence of a radical initiator to form soluble polymers difinecl herein-a~ove, Such a radical polymerizable comonomer g~nerally inc~ des, (1) monomers containing up to 3, preferably 1 or 2, carbon-carbon ethylenically unsaturated boncls of the vi~yl5 vinylene, vinylidene or (meth)allyl type (to be re:~e.rred to as ethylenic eomonomers), and t2) monomers not containing such an ethylenically unsa-turated bond but copolymerizable with the vinyl monM~er of fo~lula (VII) or (VIII) (to be referred to as non-ethylenic comonomers), such as S02.
~ley can be used ei-ther singly or mixed with each other. ~e monomers (2) are useful) ~or instance, as a monomeric component which gives the unit -S0~ in fox~rlula (I-b) given hereinabove.
Suitable ethylenic comonomers of type (1) con-tain at most 20 carbon atoms, pre~erably 2 to ~5 ca:r'oon atoms 9 more preferably 4 to 10 carbon a-toms~ and a l~olecular weight of 28 to 300, especially 50 -to 250.
Desirably, the ethylenic comonomers generally have a ~o~.ub:ility, in water or a lower alcohol such as methanol, ethanol or propanol at 25C, of at least 0.5 g9 preferab-ly at least 1 g, more preferably at least 5 g, per 100 g 0 of such a solvent.
The etllylenic comonomer (1) is preferably selected from the following compounds ~a) and (b)~
~ a) Compounds of the following formula 14 C=C 15 (III-l) wherein Rl~ represents a hydrogen atom or an all~oxy-car.~onyl group with the aI~yl moiety containing 1 to 10 carbon atoms 9 R15 represents a hydrogen or halogen atom or a r,lethyl group, R16 represents a hydrogen or halogen atolll, an a~o~ group containing 1 to 10 carbon atoms optionally subs~ituted by a hydroxyl group and/or a halogen atom, an alkoxycarbonyl group with the alkyl moiety containing 1 ~o 10 carbon atoms, an all~anoyl grou~.containing 1 to 10 carbo~ atoms, an alkangy~oxy ~rou~ containi~ i to 10 carbon ato~s, an alkyl ~rou~ containing 1 to lp carbon ato~s substituted by the grsup -S03M or hy~roxyl group.
a phenyl group optional~ substituted by the`!'grou~ -S03M
or a methyl ~roup, a glycidylox~ group, or a group of the for~ùïa -~B~0--~H in whic~ B represents ~n e thyle~e or propylene group, and ~ is an integer of l to 8;
, 5;Z~I~

R1L~ and R15, together, ~ay represent an ethylene-dio:i~ group 9 a~d M represents an al'.~ali metal.
(b) Compo~lds o~ the follo~ing formula CII2 ,C,~12 17, C, -R1~ (III-2) CH2 CI~2 wl~ere.~n R17 and R18~ independently from each other, represen-t a hydrogen atom or a methyl group 9 J represents an oxygen a-tom or a group of the for~ula \ M / .. X

Rlg and R20, in~ependen-tly from each other, rep:~esent a hydrogen atom or an alkyl group co:n-taining 1 to 10 carbon atoms; and ~ represents an anion such as halogen ions, II~0~, , N03(-, ~IC0 ~ and H3C~C0 ~, Typical examples of comonomers represented by the above formulae (III-l) and (III-2) are given below.
(1) Aliphatic olefins C~2=~2. CI-l2=ctl-c~I3~ C~I2=C~-1 C~2 CH3, ~ I2=CIl- (CH2)3'C~[3~ C~I2=C~C~.I ' C~I2 C\C~I

CH =C~ 2 5, H3C-C~=C~ CTI ' H C~ ~C;I3 ,~ Cll 3 . T
5 2 CI L C ~C~ 3C CI1=CI1- CH3 (2) Hetero atom-containing aliphatic ole:Eins CT-I2-CH-CN, CII2-C(CII~)~CN, CII2=CI-I-COON, CI-I2=C:~IO(,~I3 9 ClLI2=CTlIOC2~I5, C~2=C~IOC2~.LIL~C~e ~
CH2=C~CH7)-COOH, CTH2=CHC~, CM2=CHF, CH2=C(C,e)2, CII2-CF2~ CH2=CII~S03M, CH2=cIl~cH~.
~I2=cH-cH2-so3Na~ CH2=C(CH3) CH2 S03 O O
CT.I2=CIlCN(CH3)29 CH2=C~I~CN(C2H5)2, ,,C~ f C~LI3 H C CH-C 3 ~ ~l3C~CH=C
3 -COOCH~ -COOC2H5 (H C~ C-C 3 ~ (~I7C)2C=C'~ 3 3 2 - COOCII3 ~ ~ COOC2H5 F ,C CF2 ' F ~C=C F ' Cl~ -CF27 F2C=CF2' Cl~ C CF CH C C~ O CH =C C ~ -CI

O O

H2 C ~ c ~-C2~I5, C~I2=C~ ,,N-C3~I7, 8 o o o CH2=C~'C~N(C2~ OH)2, C~I2=~JC . ~ O
O O
CIl2=c~ C ~ ~T C~13, Cl-I2=CICl`T~_~S, ~I~=CH~C N.CH2~CH~CI-T.2Cl, CII2=~1-C N
O O
CH2C ( CH3 ) C N ( CH,~> ) 2 ~ CI12=CH C ~ CII3, O O
CII2=CII-C-O~I3, CH2-CII-C-OC2T.15, " ~45~
~6 -O O
C~F-12=CII.C~OC3I-I7, CrI2~CrI~C~OC4IIg, O O
Crl2~CH-O~C~CH3~ CT1~2=CI.O.C.C2TI5, O OI-I
CH2=ciI~O~C-C4i-Tg~ C'T''12=CFI~C-O~CFl2-CTT^C'~I2Cl~
O O
CTI2=c(CI~ c-o-c~2-c\I~crI2~ CH2 C 2. 4 O ~
CH2=CE~C-O-~II2~C r ~2~ ~ H, CH2=CHI~J

HOOC-CJI=CH~COOH, CEI2=C(COOH)2 (3) Alicyclic olefins ' 0 ' ¢~ ' (4) Heterocyclic olefins O O O O
¢ ,~O , ¢ ~I , ¢ N-CFI3, f N-c2M5 o o o o (5) diallyl compounds ~ / 2 // 2 CII C~I crI cIT, C-T-~ ~T~I
J
CI~ ~CII2 ~ ~ C~3 ~ 0/

CFH,3 CrI ~, C2h5 \C2~[5 ~ ~7 -I~he a~oresaid comonomers should be use~l such tha-'~ a~ter the amine modi~ying -treatment to be described, the resul~ing copolymer should have an active amino group con-~ent o~ at least 0.5 milliequivalent per gr~n of the copolymer, Generally, the proportion of the comonomer is up to 70 mole%, pre~erably 10 to 50 mole%.
Among the comonomers (1) to (5) above, ethyl-vinyl ether, methylvinyl ether~ chloroethylvinyl ether, styrene and styrenesulfonic acid are preferred as comono-mers to be copolymerized with maleic anhydride and (meth) acrylate esters, A second method ~or preparing the inte~ediate po~ymer having the recurring ~nit of formula (V) comprises radical-copolymerization of a monomer of the following ~o~ula which will provide the recurring unit of ~ormula (I~b) CH CH

~-I C~I
b-l~
` C
~E \COOR~301 wherein E and R801 are as de~ined hereinabove, wi~ sul~ur dioxide, ~le polymerization can be easily carried out by a known method (e,g,, the methocl described in Japanese Patent Publ~cation No. 14587/66) in a pol~r sol-vent such as dimethyls~lfoxide in the pres~nce of a radical initiator such as a ~ersulfate.
A third ~etho-d-for preparing the i~termediate poly-mer having the recurrin~ unit of formula (V) co~prises i~-troducing the group -Y-Z-~ (and -W-Z-T) into the corres-pondin~g precursor havi~g no:group -Y-~-T ~and -W-Z-~)O
~his method is e~peciall~ effectiv~ for ~rov~ding a solu-ble ~oly~er having th~ recurring unit of for~mula (I-c) in-cluding formulae (I-c-l) and (I~c-2).
Accordin~ to this net~od, a carboxyl~group~ or a sulfo ~roup~ or a reactive derivative of such a group can be introduced in a manner known ~ se into an aromatic polymer composes substantially only of a recurring unit o the following formula which corresponds to formula (I-c):
(Gll)d ( 21)e -R9 ~ -U ~ c-l) wherein Gl1 and G21~ independently from each other~ re-present a halogen atom~ an alkyl group containing 1 to 3 carbon atoms, or a haloalkyl group containing 1 to 3 carbon atoms, and R9~ U~ cq d and e are as defined hereinaboveO
Specific examples of the recurring unit of the aromatic polymer are given belowO
CH3 ~ oH-2Br ~ CH2Br CH3 CH3 CH2 r o~S2 ~3~ ~~~C~

O ~SO ~)--O~C~I2-~

o...~so2~--~~~3~

As stated above~ the molecular weight of this polymer is on the order of several thousand to 10 -times thereof~ and therefore~ their degrees of polymerization are about 20 to 500, preferably 50 to 300O
Introduction o~ a carboxyl group~ a sulfo group or a reactlve derivative of such a group into these aromatic polymers can be carried out by various methods~
such as sulfonation of the aromatic ring, Friedel-Crafts acylation of the aromatic ring and subsequent hydrolysis~
and the halogenation of -the aromatic ring~ followed b~

- 3~ -cyana-tion and carbo.xylation. These func-tional groups prov-7cle reaction si-tes in -the amine modifying reaction to be described hereinbelow. l`hus, the suitable content of suc7tl a functional group is at least 0.5 milliequiva-len.t to 20 milliequivalents, preferably 1 to 20 milli-e~uivalents, per gram of t7ne polymer~
The intermediate polymer prepared in -the above man..ner is then converted to a soluble polymer containing ~le recurring unit of formula (I) by treating it together wi~. the amine of formula (VI).
The amines exemplified hereinabove as the po~7amino compound can also be used as the amines of fo~mula (VI).
The amine compound of formula (VI~ is reacted wi-tlh the intermediate polymer to impart moderate hydro-ph:i.li.city and solubility to the polymer, and also provides a crosslinking site f~r a crosslinking reaction to be described hereinbelow. Accordingl~, such a polyamino compound prefer-ably has as many amino groups per molecule as possibleO
T:Iowever~ the use o~ a polyamino compound having -too hign a molecular weight tends to cause gellation in the amlne mocl.7..fication of the aforesaid intermedia-te polymer.
Furthermore, if the number of amino groups is too large, many unreacted amino groups will remain in the cross-linked polymer formed by the crosslinking reaction to be described hereinbelow. Tllis undersirably causes a reo.uction in the oxidation resistance of the polymer.
From the standpoint of the oxidation resist~nce of the final membrane~ suitable amino compounds are pipera~ine, alkyl-substituted piperazine and N3M'-di.alkyl-substituted ethylene-diamine.
Preferably,such an amine moclification reaction îs carried out as quantitatively as possible so long as gellation owing to an intermolecular reaction cloes not tak.e place, One example of the amine modifying reac-tion of e i.ntermedi~te polymer is schema-tically sho~m as followso ~s~

o / \
O=C C=O
~CH2CH-C~-C~ + H~ MH

--C~2CH--C~l--CH~
C=O COOll C=O

~N) ~N) To avoid gellation in this amine modifylng reaction, it is preferable to carry out the reac~ion in a d:ilute solution of -the polyamino compound. Usually, by adding the intermediate polymer to a polyamine solu-tion ~laving a concentration of 1 to 20% by weight, pre:~erably 5 to 10% by weight, and carrying out t~e reaction at a relatively mild temperature range, preferably at ~oom temperature 50C, the amine modification ~s acl~:~eved without involving gellation.
Tlle reaction solvent ~For the amine modifica-tion react:ion may be any solvent which does not easily react wilil tlle intermediate polymer to be modified with -the ami-ne, and the polyamine compound. In view of` the solu-b~ ties of the starting material and the product, and -the ease of post-treatment, suitable solvents are water 9 ethers such as -tetrahydrofuran and dioxane, alcohols sucll as methanol, ethanol and propanol, and aromatic hydxocRrbons SuGll as benzene and toluene. Water, methanol 9 ancl e-~hanol are preferred, and wa-ter is most preferred.
T~e amount of the polyamino compound used in the amine modi~ying reaction is not cr~tical, and can va~y as desired 9 according to its type, etc. Generally, ~le suitable amount o~ the polyamino compound is 0.5 to 1.5 moles, especially 0.~ to 1 2 moles~ per e~uivalent 5Z~i~
_ 41 _ o~ the reactive groups (-Y-Z-T and -W-Z-T) contained in tlle intermediate polymer. If the amo~t of tl1e poly-amino compound is less than 0.5 mole per equivalent of t~le reactive groups in the intermediate polymer, gellation will occur during the amine rnodi~ying reaction, or a semipermeable membrane obtained a~ter -the crosslinking reaction to be described hereinbelow will tend to hava a rec~uced water flux. On the other hand, when the amo~7~t o~ the polyamino compound exceeds 1.5 moles per equ:ivalent of the reactive groups, the unreactecl amino grov:Qs will undesirably cause a reduction in the strength ancl salt rejection of a ~emipermea~e membrane obtained a~ter the crosslinking reac-tion.
The amine-modified amino-containing soluble pol~er is used for the formation of a membrane either as such or after dilu-ting the reaction mixture, or after isolating and purifying the reaction mixture.
According to another procedure, the soluble pol~ner containing the recurring ~mit of formula (I) may ZO be prepared from a monomer having -the groups YI Z-~' (ancl ~ Z-M ~R ~.
This method is especially useful ~or vinyl monomers, and is performed by the direct radical polymeri-zation of an amine-modified vinyl monomer obtained by reacting a vinyl monomer having an atom or f~mctional group capable of reacting with an active amino groulp with the Polyamino compound (~IM~ Or it can be ca~ried ou-t by reacting the active amino groups contained in the group ~ Rl in the amine-modi~ied monomer with an ino-rg~anic acid to form an amine salt, radical-polymerizing t~le am-ne salt9 and neutrali~ing the product with a base.
PreParation of a polymer by the above method is schemati-cally shown below ~or easy understanding.
Cll-I3 C-I2 CH-COC~e + HNC~12CH2N~IC I3 i2~3 _ ~2 -~I2=CI-I 1~
O_C~ CII2C~2N, i..Cl ~ ical ~ I2C~
O-C~ 12C~I2~I2C ~ base -~IC~

CII2C~ -~
O=C-NC~I2C~I2 ~I3 CII~

mus, suitable base pol~ne~ used to make ~he se,m:i.;oermeable membrane in accordance with this irlvention inclucle not only (I) polyrners composed substantial~y onLy of the recurring ~mits of formula (I), but also (II) copolymers described below.
Suitable copolymers for use in this invention are composed of (A) at least 30 mole%, pre~erably at least 50 mole~, more preferably at least 70 rnole%, o~ the recurring unit of forrnula ~I-a), (-[-b) or (I-c), and (B~ up to 70 mole%, preferably up to 50 mole%, more preferably up to 30 mole%, of at least one recl7rring unit selected from those of the following for~ula -C - C- (IV-l) wherein R21 represents a hydrogen atom or an a~oxy-carbonyl group with -the alkyl moiety containing 1 to 10 carbon atoms;

. ~' S2l~
4~ --R22 represents a hydrogen or halogen a-tom or a methyl group 7 R23 represents a hydrogen or halogen a~tom~
an ~lkoxy group containing 1 to 10 carbon atoms optionally mono-- or di-substituted by a h~droxyl group and/or a halogen atom, an alkoxycarbony group with the alkyl moiety containing 1 to 10 carbon atoms, an alkanoyl group containing 1 to 10 carbon atoms, an alkanoyloxy group con-tainlng 1 to 10 carbon a~toms, an alkyl group containing 1 to 10 carbon atoms mono-substituted by the group -S03M or a hydroxyl group~ a phenyl group optionally mono-substituted by the group -SO~M or a methyl group, a glycidyloxy group, a group of the formula ~B_C ~ EI in which B represents an ethylene or propylene group and j is an integer of 1 to 8, the group ~ / 1 , the group _o-cH2-cH2~cH2-N ~

--O-CH~-CI-I-CH2-1~ 1 in which Rl and R2 are de~ined hereinabove;
R~l and R22 together may represen-t an ethylenedioxy group;
o R22 and R~ togcther may represent -O-C-O-;
and M represents an alkali metRl 7 and those of the following formula / CH2 _~
-C-R17 R18-1C-c~2-R~4 (I~--2) CH2 - ~ CH2 J ~
wherein R17~ R18 and J are as defined with regard to formula (III-a), and R24 represen-ts a direct bond or -~S02-~

~5;~

Typical examples of especially suitable soluble pol~mers containing the recurring units o~ ~ormula (I) are ,given below. These examples are ~or the purpose of :Eac~litu-ting the understanding of the invention9 and are in no way in-tended to limit -the scope of this inven-t~.o~.
4CH~CH ~ CT-T2CH~b- R , ~ CI2CI~ CH2cH ~ R
O-CoO~3 O-C-N ~ -,C,c2-5 R
c-~3 ~ O_C-N F~l~ ~ O=C Q-C-~ 101 O=C-OCII2CH20~IOCH-T2c~IcTI2c~ 201 OH

O C O=C_~T 101 2I ~ O=C N 101 -~101~1 OCEI CTI ~ 101 R201 OCH CHC~2 2.` ~, 2, 2 -R '201 OI~I 201 ~C~I2C~ a~CH2C,~I~Rlol, ~cI2cl~c~I2ct~l~ R
CsIo3Na R~ol so.32Na R

~jC ~' O-C-M~- 101 CH~ CEI3 201 CI-I2-S~CT12C I
R

CO~rI `~
2~ o=~

__ç, O~CH2-)~C;-CH2-C-CH2~b ' o COOHo=c_N~ R101 (Rlol and R201 are as defined hereinabove~
a~b = 3:10 to 1:1) ~ R
-CH-CH- R CT,12C-i~T~ 101 N~ 101 , ~2C- J,-R101 201 ,CH2C N 101 ,, ~ R
CI12 ,C F~201 , -C~2 C~C_I~T_ R
cOOR8ol a P201 -CH2C- R ~ ~C~I2CH-CH-CH_ R
R201 O=C-N 101 --R~

CH COOH
-C~I2-C~ R O

. I R- O=C-N
O=C-~ 101 ~ 46 ~
COOlI CI3 COOTI
--C~I2cH - ciI - cJ-T - P--C~ ~2C -- C' l~C'rT~ :r~
COOR O-C-~ COOR ~

COOTI COOH
CII2~T -- C~ CLI~ --CH2CH--c-T--CI-T--OR~301 R201 CH2CH2X ~201 (X: Br, C~) C, ~T-I 3 ~C~I2--C-- ~ --C~r-I2--CT-I--C~I2-S02-M 10 C:-I SO Li ~ ~ 10 _CLI2C~I_ C1~2~

o=G-r~ 101 ,S02'L~ 101 R20l F~20 C~I~; CH ~;

0~3rJ~ Rlol ~o N-- 101 ~201 R201 C~I3 C~I3 --Ci-I--CH2--C'-I~ R--C--CH2--C--COOI-I O-C-M R101 ~ COOIIo=C_N O

5~

'.the a:Eoresaid poly.ners can be used singly, or as a mixtvre with eacll ot'ner.
So long as the objec-ts of this invention can be ac~ie~ed, the polymer having the unit of formula (I) can be usecl as a blend with another polymer. Such other polymer includes those which have the ability -to form a wa-ter~soluble or aqueous emulsion, and ~orm a polymeric alloy as a whole after blending with the polymer~having the W1it of formula (I) and the crosslinking of t'.le polymer having the unit (I3, and which even when the water-soluble po~.ymer is not crosslinked, can by -themselves become sv~starttially insoluble. ~e proportion of such a polymer vari.es according to the proportion of the structural unit of formula (I) in the above polymer. It should, however, be such that in the resulting blend, the proportion of the structl~al unit of formula (I) is at least 50 mole~
I~ t,he proportion of the other polymer is too high, it is di~icult -to form a polymeric alloy. Hence, -tlne other pol~Qer is blended usually in an amount of not more thart 30 parts by weight, pr~ferably not more thart 10 ~arts by weigh-t, per 100 parts by weight of the polymer llaving the unit (I).
Use of such a polymer blend ma~es it possible also to control the flexibility a-nd hydrop1ailicity of the resulting composite membrane.
Examples of the other polymer having the afore-said properties include polyvinyl alcohol, poly~inyl pyrrolidone, poly(sodium acrylate), poly(sodium meth-acrylate), polyvinyl methyl ether, poly~inyl ethyl ether, a copolymer of methyl vinyl ether and maleic annydride9 a copolymer of vinyl acetate and ethylene, polyvinyl acetate and partially hydrolyzed products of these polymers~
To produce tne semipermeable eomposite membrane of the in~ention from the polymer conta~ning the recurring un:t of formula (I), it is necessary to crossli~ the polymer while it is deposited on at least one sic1e o~ a microPorous substrater ~5~
_ 48 _ Deposi-tion of the pol~ner on the microI)orous substrate can be effected by applying a solution of the base polymer con-taining the recurring Wlit of fo~mula (I) -to the substrate.
The solvent ~or the preparation of -the solution of tl!e base polymer may be those which do not substantially dissolve or swell a substrate to which the solution is applied. Specific examples include water, lower alcohols~
acetone~ -tetrahydrofuran, dimethylsulfoxide, l`~T-methyl-pyrrolidone, dimethylfo~namide, dimethylacetamide c~nd a mi~ture of a-t least two of these compounds. 0f these, wa-ter and aqueous mixt~lres of these consisting mainly of water are preferred The concentration of the base polymer in the sol-vent is no-t çritical, and can be varied widely de~ending up~n the -type and viscosity of the pol~ner 9 etc, Generally, it is ad~antageous to use the polymer in a ConCen'GratiOn o~ at least 0.05% by weight, preferably 0.07 to 10S by we:igl-t, more preferably 0.1 -to 5% by weight,'based on t,~e weight of the solution.
~ le base polymer is deposited in the form of ttlin fi~ll on the microporous substrate before crossli~-ing. This cleposition can be performed in quite the same ma~ er. as a co~ventional method disclosed, for example, i~ t~le above-cited U. S. Patents. For example, the t~lin fi~ can be formed in si-tu upon the microporous substrate or it c~ be formed separately, as by a floa-ta-tion de~osition method.
Substrates that can be used may be any of the types conventionally used in a reverse osmosis process.
The~J include porous glass, sintered metals, ceramics, c~nd organic pol~neric materials such as cellulose esters, styrene resins; vinyl butyral resins, polysul~one~ chlori-nated polyvinyl chloride, etc~ described in U. 'i. Paten-t N'o, 3,676,203. Polysul~one film has been ~o~d to be a particularly ef~ective support material ~or -the membranes of -t'ne invention, and chlorina-ted polyvinyl chloriclQ is - ,: . .. .

~S2 L~9 _ anot~ler very effective support ma-terial. Preparation of pol~sulfone microporous substrate is described in Of~lce of ~-aline Water Research and ~evelopment ~rogress i-~eport No. 359, Oct , 1968l These substrates preferably ha~e a sur~ace pore size of generally 100 to 1000 ~, but are not limited to these specific sizes. Depending upon the use of the final mémbrane product 9 surface pores ranging in size from about 50 ~ to about 5000 R may be accept;able.
~le substrate may be of an isotropic structure or an anisotropic structure, desirably of the latter struc-t~lxe, When the membrane constant of t~le substrate is less than 10 4 g/cm2-sec-atm, the water permeabillty of t'he substrate is too low, and when it is more than 1 g/cm2-sec.a-tin, the salt rejection -tends to be extremely low.
Accor~ingly, preferred membrane constants are 1 to 10 4 g,/cm2.sec atm, and the best results are obtained with a mem~rane constant of 10-~ to 10-3 g/cm2-sec atm. m e term "mem~rane constant", as used herein, denotes the a~i~ount o~ pure water which permeates the membrane under a prcssure of 2 kg/cm2, and is eY~pressed in g/cm2.sec-atm.
Preferably, the substrat;e used is rein~orced at its back with a woven or non-woven clo-th, etc. ~xarnples o~ the woven or non-woven cloth are those of polyethylene tereplllthalate, polystyreneJ polypropylene, nylon or vinyl chloride resins.
When it is desired to form a thin film o~ the base pol~ner in situ on the microporous substra-te, ~he microporous substrate is treated with a solution of the base polymer. The treatment can be performed by coating at least one surface of the substrate with a solution of the base polymer by a suitable method such as solution casting, brush coating~ spraying~ wig coating or roll coating9 or by ~mnersing the substrate in a solution of the base polyrner.
'~he substrate so -treated by coating or imrnersion is ~hen sub~ected to a drain treatment. The drain trea-tmen-t can be carried out generally at room tempera-ture for 1 to 30 mimltes9 preferably 5 to 2G minutes, As a result, a substrate is obtained which has formed t7,~ereon a thin layer of the polymer solu-tion with a sui--~ab:Le thickness that can vary according to the concent-ration of -the pol~rmer in the polymer solution. I~sually, a -th:in ~ilm material of the base pol~ner having a total -t~:!..ic1mess of about 1,000 to about 50,000 ~, preferably about 2,000 to about 10,000 R, is deposited on -the -10 sur~ace of the substra-te.
~ le substrate on which the base polymer has been depositecl can be directly su.bjected to a cross-aing trea-t~ent.
The substrate having the thin film deposi.tecl or.~ t,le support is then subjected to a crosslinking treat-ment by using a polyfunctional compo~d containing at lea.s-t two fun.c-tional groups capable of reacting with the active amino group to crosslink t.he thin film material O:'L t,.he base polymer on the substrate.
The crosslinking reaction is effected by an i~t,er~acial reaction between t~le surface of the film materi.al of the base polymer ancl the polyfunctional compoulncl-to produce a thin ~ilm having permselecti.vi-ty on the surface of the substrate. Since the main ~urpose of -the polyfunctional compo~d is -t;o provide an inter facial reaction substantially concentrated on or confined to t~e surface o~ the film of the base pol~ner, the poly.~unetio~al compounds should be pre~erably selectecl in aceorclance with the principles of interfacial reaction.
30 r~O:r example, when the base polymer fi~l is coa-ted from ~ aqueous solution, the polyfunctional compound or polyf~1ctional compound sol~ition should be substantlally insolu~le in water. For this and other reasons, ~arious polyfunctional compou~ds compatible with non-polar orgc~ic solvents suc~ as hydrocarbons but subst~rtiall~J
.insol~ible in water are preferred, Selection of the poly~ ctional compounds is also governecl by emp:i.rical ~ ~ ~ 5 co~di-tions, e.g. -the salt rejection and f:lux properties or resistance to compaction of tlle ultimately obtained membrance, and the selection can be achieved easily by any one skilled in the art by performing small-scale routine experiments.
me functional groups of the polyfunc-tional compo~rnds that can be used in this invention are either one of acid 'nalide groups (-COX), sulfonyl halide groups (-S02X), M-haloformyl groups (_N~COX), llaloforma-te groups (-OCOX), isocyanate groups (-~TCO) ancl acid anhydricle grO~IpS ( C-)- At least two, pre~erably 2 or 39 of these :Ew~ctional groups ca-n be contained per moleeule.
In addition to compounds having such ~unctional groups, cyanuric acid chloride of the following formula ~ C~ G~ ~
~ N ~ M J
C~ ..
C~l also be used in tllis invention as the polyfu~ctiQnal compounds Pre~erred funetional groups are aeid halide, su:l~onyl halide and acid anhydride groups, the first two being espeeially preferred~ Another suitable fune~
tlona]. group is an isocyanate group. Two or more ~unc-tional groups present in one molecule may be of t~e same type or of different types. rne polyfunctional compounds generally have a eyelic structure, and may be aromatie, he~eroeyclie or alieyelic. For the purpose of the present invention, aromatic polyfunetional eompov~lds have been ~ound to be espeeially effeetive.
Any mononuclear or polyn~lclear ~espeeially, binuelear) aromatic polyfunctional eompounds having at least ~W09 preferably two or three, functional groups bo~decl to the aromatic ring and 6 to 20, preferably 6 to 15, carbon atoms can be suitably usecl in the present :i~..vention. Pre~erably, the aromatic ring or rings should z~

not contain a substituent other thall the above func~ional gro7l-ps~ Ilowev~r, one or two groups ~hich do not substan-tially af~ect the crosslinking reaction~ such as lo~Jer al7..~ 1 grovps, lower alkoxy groups or halogen atoms, may be presellt on -the aromatic ring.
A~ especially desirable g~roup of the aromatic polyf~nc-tional compo~ds includes those of the ~ollowing fo~v.la R37 R3~
Ar (XVIII) 1~ wl!.erein Ar represents a benzene ring, a naphthalexle ring, or -c.tle ring ~-R~o ~ in which RL~o represents -CH2-, ..~
-C- , -O-, S02- or -CO- 9 R37, R38 and R39, independen-tly C'':. 5 .~rc\!n each other, represent an acid halide, sulfo.r.l.yl ha~icl.e, j.socy~late, N-haloformyl or haloformate group~
es-pecially the first -three groups; or R~7 and R-'~S together reT?resent an acid a~lyclride group9 it i.s especial~.y delC~ able that R37, R3~ a~ 39 hal:i.cle and sulfonyl halicle groups. Typical examples o~
tl~.e a.romatic polyfunctional groups are shown below.

ICOCl COCl CO~l COC ~ ~ COCl Cl~C ~ ~ ~ S02~1 o 1~ ~1 "
-~--So2cl , o~ C~ CCl ,~ C ~ C~~
CH2COCl o 8 o CH2COCl ~ 53 -O O O O
C ,~~~ C~ ~ ~C _ C~
o~ I~I~J `o, o ~ ~1, ,o ~
~ ~\~ C ~ C
" " ~ "
o o o o COCl MCO ~II
GOCl , ~ ~ 3 NCO
NCO

C102S ~ ~-R41 { >-S02Cl~ ClOC~1 ~ >-COCl, GlOC3~ ~ ~0COCl and ClOCO ~ -R41 ~ -OCOCl (R41 represents a direct bonding, -O-, -CH2-, -S02- or -C- ) ClI3 Especially advantageous aromatic polyfunctional compo~nds are isophthaloyl chloride, terephthaloyl chloride, tr:imesoyl chloride and 3-chlorosulfonyl-isophthaloyl 10 ch:l oride, Preferred heterocyclic polyf~ctlonal compounds t~lat can be used in this invention are 5- or 6-membered lleteroaroma-tic or heteroalicyclic compounds having two or ~h.-ee functional groups bonded to the heterocyclic ring and containing 1 to 2 nitrogen 9 oxygen or sul~ur atoms as heteroatoms. ~xa~ples are as follows:
O ;.
COCl Cl-G

COCl , GOCl ClOC COCl ~45~
- ~4 -C].OC _ ~ , COCl ClOC ~ ~

ClOC - ~ COCl , ClOC - ~ COCl ClOC ~ COCl ~3 (R42 = O, S ) ~I3C
ClOC'-~T~ ~,N~COCl, ClOC-N ~ -COCl, ClOC-I~T\ ~-(C-I2)o-3 ~ N~COCl Preferred cyclic polyfunctional compound.~ -that can be used are those having 2 or 3 functlonal groups bonded to -the alicyclic ring and containing 5 to 20, pre:r.erably 6 to 15, carbon atoms. l~amples are as ~ollowso COCl COCl ,COCl C'OCl ,~ ~ ClOC

COCl COCl COCl C'~:[ ~ .
ClOC~C~I2~COC19 ClOC- ~ >~ ~ ~COCl ~,, ~CO l~iCO
ClOC~ ~ ~ O ~ --COCl, ~
MCO cT~l3 OCN ~ \-C1~2 ~ ~ --NCO, OCM ~ C ~ ~>-MCO, ~ ~5 ~
aCI~ ~ O { >-~CO, ClOCO- ~ -OCOCl, Cl~~ Ll~ OCOCl (Ll represents a direct bonding, -0~~ I2-, --SO2-- o~ - C--~ .

Pre~erred aliphatic poly~unctional compo~mds that can be used are those having 2 functional groups and containing 5 to 20, preferably 6 to 15, carbon atoms.
~anples are as follows:

ClCCH2CI`I2CCl, ClCCI-I2CM2C~I2CCl, ClCC~I2C.T~:.12C~I2CTl-I2CCl, O O O O O O
ClCCrl ~I ClI ~H CI~ CCl ClCCT-I CH CH ~-f Ci~2C!~I2CCl, O O O O
ClC~ C:H2~CCl, ClCOCH2CTI20CCl, ClCOC~2CT:I2C~I20CCl, O O O O O O
OCN ~CM2~ NCO
m e aromatic heterocyclic or alicyclic polyfunc-tional compounds can be used either alone or as a mixture of t~o or more.
It has been found that the salt rejecting and/or flux properties of tlle ~inally obtained membrane can be improved by using trifunctional compounds rather ~an di-fvnctional ones when they are used singly, and by using a combination o~ a di~unctional compound and a tri~unctional compo~d when they are used in combination. Th~lS~
especially preferred polyfunctional compo~ds to be used in tl~e present invention are trifunctional aromatic com~o~mdsg ancd mixtures of difunctional aromatic compounds ancl trifunctional aromatic compounds. ~hen a mixture of a cl:if~mctional compov~d and a trifunctional compovncl is usecl, the mixing ra-tio between -them is not critical.
Ge~nerally, the weight ratio of -the difunctional compound to l-~he trifunctional compolmd is from lOol to 1:3~

z~
-.~6 -pref'erably fro1n 5-l to l:l.
The crosslil~ing of the ~ilm material of the base pol~mer can be perfo~ned usually by contactir~g the f~.~n7.~ith a solution of -the polyfunctional compouncl.
~ e solvent used -to dissolve the poly~unctional compow~d sl~ould not substantially dissolve the base polymer and -the substra-te ma-terial 9 and includes hydrocarbons such as n-hexane ? n-heptane, n~octane, cyclohexane, n-nonane and n-c7.ecane. ~e optimal concen-tration of the poly~.7~ctional comQo~d in the solvent may vary consiclerably depending upo.l-t]le specific compouncl, solvent~ subs-tra-te, etc., ar).c7~i.s best determined experimentally. T10wever, concent-rati.on of about 0.5 to 5.0, preferably about l.O to 3.0%
by we.ight are generally satisfactory.
Convenien-tly, -the crosslinking is accomplished on 'che interface be-tween the film and the solu-tion by imme:rsing -the film in the solution of the polyfunctional co-.mpound, In order to prornote this crosslinl~ing reaction, i-t .is possible to include a crossl:inking accelerator into ~0 ~-~e fi.~n of the base polymer. mis accelerator serves tG
he7,.p -the polyfunctional compourld d:Lffuse into the polymer, a~c7./or to capture hydrogen halide released a-t the time of crossli3~king reaction. Such an accele:rator may include, for example, soluble basic compo7~7~ds ancl surface-active ageo.ts.
Advantageously, sui-table soluble basic compounds have a solubility in water or a lower alcohol such as me-~!.a71ol, ethanol or proparlol or a mixture thereof of at l~ast O.l g, preferably at least 0.2 g, more preferably a-t least 0.5 g, per lQO g of water, -the lower alcohol or a mi~.xture thereof a-t 25C. As swch compounds, inorganic bas7.c compounds and organic basic compounds llaving the above solubility can be mentioned~ Any inorganic basic co-m7.?ounds having ~le above-~entioned solubi~ity can be usecl, The organic basic compounds should desirably have a p7ca value of generally 5 to l~, preferably 8 to 12 Examples of the soluble basic compouncls are (l~

inorganic bases such as sodium hydroxic1.e, potassium h~clroxicle, lithium hydroxide, sodi.um carbonate, lithiu~
carboj:1ate, po-tassium carbon.ate, sodium bicarbonate, pc)tassl~ bicarbonate, lithium bicarbonate, sod.i.um phospha-te (Na3P0~) and potassium phosphate (I~3P0~)9 a~.~ (2) orga.nic bases such as triethylamine, trimeth~l-ami.ne, diazabicyclo~2,2,2)octane) hexamethylenetetramine, et.l~..ylenediamine 9 triethylenetetramine 9 met}lylarnine ~
et.hylamine, triethanolamine 9 diethanolamine, pyri.dine, M,:.-c1imethylaniline, N-methylpiperidine, and ~ methyl-py.rroli.dine.
These basic compo~mds capture hydrogen halide, w~ich may be forrned by the crosslinking reaction to promote tlle crossli3~ing reaction, positively partici-pate in the crosslinking reaction itself, and also have the effect of i-mproving the mechanical strength or o~1.dation resistance of -the resulting semipermeable mem~rane, They are especially sui-table as crossli3lking accelera-tors~
The basic compo~md is used in an amo~mt of generally 0.5 -to 2.0 moles, preferably 0.7 to l.~. moles, per equivalent of -the active amino group in the polymerO
m e interfacial crosslinking reacti.on be-t~een th.e surface of -the film and the polyf~ctional agen-t can ~5 be carried out at about -10C to about 100C, pre~erably 20C to 50C, for a per.iod of lO seconds to 30 minutes, pre~erably 30 seconds to lO minutes. r~his interfacial reaction can be performed so that it is concentra-ted iargely on the surface of the film, and it is not necessary to reduce the water conte~t of the internal reg.ions of the fi~n.
~ 1en~ tlle film supported on the subs-tra-te is o-ptionally subjected to a clrain trea-tment to drain the e~cess of -the polyfunctional compound. solution for lO
seconds to 2 minutes, ancl then heat -treated at a tem.perature of 70 -to 150C, preferably 90 to l30C.
IS.~..;..s can complete the crosslinking reac-tion ancl achieve ~ 58 ~
-tlhe i~solublliza-tion of the film of the base polymer.
Crosslinking agents which -tend to exist as gases at rooin temperature, for example oxalyl dichloricle or phosgene, can be contac-ted in the gaseous sta-te with -the aforesaid membrane to induce a crosslinking reactionO
The possible structure of the polymer o~ this irven-tion crosslinked in the above manner along with -the amino mcdification and crosslinking reaction is shown by the following -three examples.

(1) ~ CH2-CH ~ C~ - C~ ~- HN~~~N~
COOCH30=C\ C=O ________~
o -~C~2CH - C~ . CH ~-COOCH3 O=C C=O O

CH C~ - - CF1 - CE~ ~~
2~ ~ t COOC~3 COOH C=O
~,~
O-C

O=C
(2) ~ CH2C~ - C~ - CH -~- CH~l~ ~I2 ~2NH ~3 O=C C=O

GH2CH - CH - CH ~ ~ O
I COOH C=O CQC C
N-C~30 0 ~2 C,~2 N~C~3 CH - C~t ~
~00~ C=O

C~I2 ~I3-N

C ~ COOH

C=O

IIN,JNH
(3) ~I2C~ GE~3 ~~ CH2CI~
coc,e ,. ~ c=o ~' N' ~3 C~C-M ~ COC~
C'H2C~I
C_O

CH3 N' C=O
~N~

C=O

Thus~ a composite membrane is obtained which has a ~hin ~ilm of the crosslinked polymer having perm-selectivity on the surface of the microporous substrate.
me resulting membrane can be used directly ir~
ap-plications to be described below. If required, lt may be subJected to a post-treatment step to be describedO

5~
-- ~o --For example, the membrane can be -treated with a solution of a compound containing a metal atom having the abi.:li-ty to form a chelate with a primary amino group, a seco-ndary amino group, a hydrox~l group, a carboxyl group and.~or a sulfo group to form a membrane in which such a fv;-ctional group that may be present in the crossl.i~ed thi.n film is chelated with the metal atom. rnis membrane has e~llanced flux properties as compared with the ~lntreated membrane. Examples of the metal compound which can be used for this treatment include BaC12, MgC12, HgC12, CuC12, CaC12, FeC13, AlCl~ and CoC13. Of these, FeC13 9 CaC12 and MgC12 are preferred.
This treatment can be easily performed by im~ersing the membrane in &n aqueous solution of -the metal compound (in a concentration of 1 to 30~/0 by weight) for about 10 to 60 minutes.
The membrane thus obtalned can be trea-ted with a ~iquid polyepoxy compo~md, acrylonitrile, a lactone such as ~-^butyrolactone or ~-lactone, or propaneslll one to improve its oxidation resistance ancl salt rejec-tion ~ur-t'iler~ This treatnent can be performed by i~mersing the membrane in a solution (concentration about 0.5 to 3~ b~ weight) of the treating agent a-t room temperature for 3.-to 10 minutes.
mus, according to ~hiS invention, there is prov:ided a semipermeable composite membrane comprising a microporous substrate and a semipermeable t,hin fil~ of the -type described hereinabove formed on one sur~ace of the microporous substrate. In the oomposite membrane9 ~!.e thickness of the semiperm~able thin film is not str.ictly set, and it may have a total -thickness o~
at least 100 ~9 usually 19000 to 4,000 ~.
~ e composi-te membrane obtained by this invention can be used in various modules, bu-t a spiral mod~le is most preferred. ~hen the composi-te membrane of -this in~ention is ~abicatèd into a spiral mod~lle, it .is ~re~erable to cover the surface of the composite 52`~13 -- 61 _ mer~ r~le with a film of a water-soluble polymer in order to protect the surface.
'~hus, it is also within the scope of this .invention to provide a protective coating on the surface of ~.~e composite membrane of the inven-tion. Depos.ition o~ the protective coating on -the tllin film is carried out by coating the barrier fi~n wi.t'n a water-soluble organic pol~n~er such as polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, polyacrylic acicl, polyvinyl methyl ether, and polyvinyl ethyl ether. Polyvinyl alcohol, -polyvinyl pyrrolidone and polyvinyl methyl ether are preferred~
The ~olymer is used as a 1-20 wt%, preferably 6~10wt, %~
aqueous solution. In a specific embodiment, the dried semipermeable composite membrane is passed through a sol~l.tj.on o~ the water-solu.ble organic polymer or coating the pol~ner solution on the sur~ace o~ this barrier ~ilm by lmown means such as dip coating, spraying, or brush coating to coat the fi~m continuously with -the solution o~ t.7.~e water-soluble organic polymer; then the water is rer.aovecl9 and to .~orm a final product, the coated semi-peI~eable composite membrane is dried at a temperature of about 50 to 150C, preferably about 90 to 130C for about 5 t.o 10 minutes.
The membrane having semi.~ermeabili~yprovided b~ t~:liS invention is very suitab:Leaas a semipe-rmeable membrane for the applications to be described because it has superior salt rejection and ~lux properties, especially fl~ properties, superior ~lexibility, high resistance to compastion and high resistance to chemical and biological degradation~ especially oxidation resis-tance and ~yc~olysis resi.stance.
m e membrane of this invention can be aclvantage-ously used as a semiperne~le membrane to separate and remove tiny amo~ts of contaminated molecules dispersed ~5 or dissolved in a liquid or gas, and can find extensive application~ for ex~lple in the desalting of sea water and brackish water, and the treatment o~ industrial S~ 3 e~ en-ts containing organic matter, liquids containing mi~:tllres of organic substances, and was-te waters from t~le food industry.
The membrane of this invention can be used es-~ecially advantageously as a reverse osmosis membrane in the method for desalination of saline or brachish water by reverse osmosis which comprises contacting the saline or brackish water ~mder pressure with the reverse osmosis membrane. This method is known, and a specific proceclure described, for exa~ple, in Ind. Eng. Chem.
FO~l~d, ~9 206 (1964) can be used. Thus, ths disclosure of ~ is literature reference is incorporated herein by re:~e:~ence.
The following ~xamples illustrate the present invention more specifically. The reverse osmosis test carried out in these examples followed the procedure described below.
P~everse osmosis testin~ethod Reverse osmosis was carried out in an ordinary 20 COJ.~. tinuous pump-type reverse osmosis device using a 5000 ppm aqueous solution o~ sodi~ chloride at a ~M ~:~ 700 and a tem~eratllre ~ 25~C. ~he o~erating pressllre w~s ~20 5 k~,/cm20G.`

~ 3~
~ e salt rejection (%) :is a value calculated ~rom tlle following equation.
I~aCl concentration ~
Salt rejection (~o) = 1 - ~ )x 100 in the test solutio~

(~1) Preparation of a ~abric-reinforced microporous substrate o _ A Dacron non-woven fabric (basis weight 1~0 g/m2) was fixed on a glass plate. Then, a solution containing 12.5% by weight of polysul~one, 12.5% by weigl~t of me~hyl Cellosolve and the remainder being ~ 52C~
63 _ di.me-thyl. formamide was cast onto the fabric in a layer ha~i.ng a thiclmess of about 200 microns. I~nediately, the i~olysulfone layer was gelled in a room temperature wa-ter bath to form a non-woven fabric-reinforced micro-porouls polysulfone membrane.
The resul-ting microporous polysulfone layer had a thickness of about 40 to 70 microns and had an aniso-tropic structure. By observation with an electron micro-grap~.l, the sur~ace of -the microporous layer was fow~d to co-rn-tain n~erous micropores with a size of 50 to 600 ~.
~ ne resulting microporous substrate had a pure water flu~ (mernbrane constant) of about 3.0 to 7.0 x 10-2 g/cm2 sec.atln.
(P~) Preparation of a composite semipermeable membrane -A 500 ml. -three-necked round-bottomed flask e~lipped wi-th a stirrer, a thermometer and a refl~
concl.enser was charged with 80 ml of dried and distilled ben~ene, 8.6 g of maleic anhydride recrystallized from chlorof`orin, 8.6 g of .. ~dis-tilled methyl acryla~e ~nd 0.7 g o~ azo~isisobutyronitrile (AIBN). After pux~ing the .i~side of the flask with nitrogen, the temperature of -I^.l~e inside of the flask was raised to 70C, a~d the mi~ture was stirred for 8 hours, when a viscous..pol~m~r prec~pitated ~le resulting polymer was thorough:Ly washed with anhydrous benzene, ancl. dried at 50C under red~ced pressure to afford 11.3 g of a white viscous sol:id polymer which was determined to be a 1~1 block copo:Lymer of methyl acrylate and maleic anhydride as a resul-t of IR and .~ analyses.
A 200 ml. ~lask was chargecl with 14.6 g of trie-~lylene-tetramine ~H21`~ CH2CiI2I~ 3T-1), 150 ml of dis-tilled water and 8.6 g of the resulting copolymer.
l~e inside of the flask was purged with nitrogen~ and ~5 heated to 50C When the mixture was stirred for 3 hours, the above polymer became completely water~soluble~
Ackli.-tion o~ 100 ml of diethyl ether to an aqueous solution 2~8 -' ~LI- --of -I;he amine-l~odified pol~ner resulted in precipitation o~`-the polymer~ ~le polymer was dried under reduced pres.sure at 50C to afford lG.2 g of a ~iscous fairltly yellow solid polymer. The amine equivalent o~ the polymer was determined by the peracetic acid-glacial acetic acid titration method7 and fo~ld to be 10.3 mil.:l.iequivalents/g.
The modified polymer obtained was dissolved ir dj.st-lled water, and filtered on a microfilter to form a ~.S~ by weight aqueous solution. The polysulfone porous membrane ob-tained in ~xample 1, (A) was dipped for 5 rnim.ltes in the aqueous solution, withdrawn from it after a lapse of the five-minute period~ and allowed to stand perpendicularly to drai-n it for 10 minutes.
The drained membrane was dipped ~or 5 minutes at room tempera-ture in a 1.5% n-hexane solution of a mixture of isophthaloyl chloride ancl trimesoyl chloride (in a 5:1 weigh-t ra-tio) as a crosslinki-ng agent, w.i-thdrawn, and drainecl for 1 minute in the air to volatilize -the 2Q n-le}~ane ac~ering to the surface of the membrane. The mei~brane was then heat-treated for 10 minutes in a hot air cl.ryer at 115 to 120C.
The resulting composite membrane was s~lbjec-ted to a reverse osmosis test using a 0.5% aqueous l`~TaCl so:!.u-tion at 25C ~mder an operating pressure of 42 5 kg~cm~-G The oomposite me~brane showed initial pro-perties represe~ted by a water flux of 103 liters/m2-hr (63..8 G.F.D) and a salt rejection of 96.4%~ ~en t~e mcr~hrane was so tested continuously for 200 hours9 the water flux became 98 liters/m2-hr (58.8 ~.F.1)3 ~d the salt reJection became 96.S%, showing very stable pro~?erties (the coefficient of compaction~ -0.009).

Instead of the trie-thylenetetramine used in ~5 Ex~mple 1, ethylenediamine, diethylenetriamine, -te-tra e-t-~rlenepentamine or pentaethylenehex~nine was reacted in t7-.e amounts shown in Table 1 with 8.6 g o~ t~e maleic an;.~.yd.ricle/rQetllyl acrylate copolymer obtainecl i.n F.~ample 1 in t'.Le same way as in ~xample 1. ~ach of the ~i~o~
mod:i.f.ied poly~ers obtainecl was made into a composite mem~rane in the same way as in ~xample 1, and tes~ed for 5 in.~ tlal properties in reverse osmosis. The results are sh.o~rn in Table 1.

Table 1 _____ ~__ __ ___ Examole Polyc~nino Gompound Amoun-t Amine Reverse osmosis ( ) equi- E~ ~s g ofltlnlte Wa-ter Salt amidnie- f~l/lUn~-hr) tiOnc fiecl t%) P(~lYmer __ _~ ~ __ __ ~thylenediamine 6.0 5.1 21 o ~ 97 . 2 ,; Die-thylenetri~ine10.3 8 . 3 25 ,1 95 . 9 I,. Tetraethylene- 18~9 11,9 100.0 95,1 pentamine Pentaethylen2- 23.2 12.8 116.2 9304 __ ~ . __ __, __ o`~,~
A composi-te membrane was obtained by mocl.ifying and. crosslinking the methyl.acrylate/maleic c~nh.ydride copolymer in tlle same way as in ~xc~mple 1 except that as a crosslinl~ing agent~ isophthaloyl chloride or tri.mesoyl chlori.de alone was used ins-tead o~ the mixture of isophthaloyl chloride and trimesoyl chlorideS and diet~ly-lenetric~mine, triethylenetetramine, tetraethylenepentamine or pentaethylenellexamine was used as -the polyc~mine compound~
~ne composite membrane was subjected to the same test as in :Li;x~ample 1. The initial properties in reverse osmosis obtained are shown in Table 2.

Table 2 _~___ ______~
c~mPle Polyanino Cross- Initial properties in compound linking reverse osmosis agent * ____________ Water flux Salt rejection ( ~/m2 hr ) (5!~o) _____,_ " Die-thylene- IPC 14,~ ~1.9 ___ ___ TMC 74.8 ~6.3 __ __ ____ ,7 Trie-thylene- _ ~ 7B.0 tetramine ~IC 165.5 95.9 _ ~ _ __ Tstra IPC 42.7 95.5 r~ ethylene- _ ____________ pen-t~nine TMC 117.7 92.7 _~ ___ __~
Penta- IPC 100.5 9~,8 9 et~ylene _ _ hexamine TMC 117.0 93.8 _ __ _ _ _ * IPC: isophthaloyl chloride TMC: -trimesoyl chloride ~ three-necked flask equippecl with a stirrer and a thermometer was charged wi-th 12.5 g of N,N-dimetXlacryl~
amicle CEI5 o C~I5 50 ml of benzene and ( CM2=C - C~ C-C=CH2 ), 0,5 g of azobisisobu~yronitrile. ~en the inside of the flask was purged with nitrogen and the mixture was stirred a-t room temperature for 15 hours, a rise in the viscosity of t,lle reaction mixture was observed. The mixture was furtller stirred at 50C ~or 2 hours, and then was poured into a large amount of acetone to precipitate a white granulRr polymer. The polymer was well washed, and dried ~u~der reduced pressure to afford ~.7 g (yield 70%) of a wh:ite granular polymer.
IR and ~R analyses of the polymer gave the s~ne spectrum as the absorption spectrum described in -~ 67 --Die Makromolekulare Chemie 88~ 133-148 (1965)~ and sugges-ted i-ts iden-tification as a cyclic polymer of the following s-tructure:

t CH2-C ~ 2 C
O=C\ /C=O
H
In a solution of 1O5 g of triethylenetetramine in ]00 ml of distilled water was placed 1 D 2 g of the above polymer9 and they were reacted at 50C for 2 hours to form a uniform a~ueous solutionO
Die-thyl ether was added to the aqueous solution to precipitate the amine-modified polymer of the following structure:
CH CH
, ~ , 3 -CH2-C-CH2--C t C-I~H2 C=0 O NH~ CH2CH2Nh~3 H
which was then dried under reduced pressureO The amine equivalen-t of the polymer was 6n6 meqO/go The resulting amine~modified polymer was dissolved in distilled water, and filtered to afford a 2~/o aqueous solu-tion, and then in the same way as in Example 1~ a com-posi-te membrane was producedO The composite membrane was subjected to a reverse osmosis test~ and was found to ~how a wa-ter ~lux of 7~ liters/m2ohr and a salt rejection 93O~/oO
~xampl ~
In the same way as in ~ample 1~ methyl acrylate and ethyl fumarate were charged at a mole ratio of 5:1, and radical-polymerized to form a copolymerO The copolymer was 25 reac-ted with each of the polyamino compounds shown in Table 3, and the resulting amine-modified polymer was crosslir~ed with each of the crosslinking agents shown in Table 3 -to form a composite membraneO The composite membrane obtained were each subjected -to the same reverse osmosis -test~ and the results obtained are shown in Table ~O

~S2~3 _ 68 ~
_ __ __ _ __, Example Polyaml~no ~nine Crosslil~ing~ agent Initial proper-compound equiva- ties i.n rever~e lent of osmosis ~ .
tlle Water Sal-t amine- flux rejec-mod fied (R/m2"n~) tion (meq./g) (%) __~__ ___ _ ____ 11 T ri ethy-:!.ene 9.7 TMC (*1) 127 95,3 -te-tramine 12 ~, ,l TDI (*2) 43 97.5 1~ 1~ 1~ CQC~ ~ , COCQ 9~ ~9.7 ~*~) ll~ ~l " CQCO' ~ CO' 103 89.4 /~c~
O
.;~Jn:lno- 7.8 IMC 5L~ 90 . 5 yl-~ ip (r~lzine 16 ~, ~4--.l)ianino-~;~clo- 5.1 ll ~7 91.2 liexane 17 ~ ~neny- 3.2 " 23 8707 di.~nine __ __ ~__ (*l): Trimesoyl ch].oricle of the formula COCQ

C~C ~~COC~
o (*2): TDI: -tolylene diisocyanate ~52Q~I

(*3): 3~Chlorosulfonylisopllthaloyl chloride s~lt'lesizecl by -the following me-thod.
CII300C COOCII3 NaOOC~ ~ ~OONa NaOH~C ~
S03Na ~03Na C~ COC~
SOC~2 S02C~

(~4~: ~ninoethylpiperazine of the formula / -2CH2-N~, ~

Distilled sulfonyl c;hloride (150 ml) was put into a 500 ml three-necked flasl~ eqllippecl with a stirrer, a dropping ~wll~el and a re~lux conclenser, and while st:lrring the material, 20 g of polyacryli.c acicl having a nw~lher average molecular ~eight of 100,000 was adcled cl:ropwise from -the dropping f~nel over the course of 2 hours ~fter the acldi-tiorl, -the tempera-ture of the in;idc of the flasl; was raised to 50-60C, and the mixtl7re was furtller stirred for 3 hours to form a uni-~o~n solution. Removal of the sulfonyl chloride from ~he solution by evaporation afforded poly(acryloyl cklloride)as a reddish brow~ solid.
~ 200 mlO flask was charged with 100 ml of di.st:llled water and 8.6 g of piperazine, and the mixture wa.s stirred to dissolve the pipera7.ine completely.
The-n, 4.4 g of the poly(acryl~y chloride) was added, anc~ the mixture was stirred at room temperature for 1 ho~Lr. r~le resulting aqueous solu-tion of -the piperazine~
mod:ifi.ed poly(acryloyl chloride) wa~ ~iltered, and 50 ml of diethyl ether was added to precipita-te the piperazine-modified polymer. r~e amine equivalent of the polymer was 409 meqO/gO
The polymer was dissolved in distilled water to form a 2% aqueous solution, and using this aqueous solu-tion, a composite film was prepared in the same -way as in ~x^
ample lo When the composite membrane W3S subjected to a reverse osmosis test, it showed initial properties re-presented by a water flux of 85 liters/m2Dhr and a salt rejection of s7~ 5%O
Exampl~e_~
A 300 mlO flask WA S charged with 80 6 g of piperazine, 150 ml of distilled water and 902 g of the methylacrylate-maleic anhydride polymer obtained in ~xample lo After replacing -the inside a-tmosphere of the flask by nitrogen, the mixture was heated to 50C9 and stirred for 3 hoursO ~he polymer became completely water-solubleO The resulting aqueous solution was purified by dialysis with a cellophane membrane~ and under reduced pressure, water was evaporated to afford 1203 g of a pale yellow solidO ~'he amine equivalen-t of the yellow solid was determined by the peracetic acid-glacial acetic acid titrating method to be 302 milliequivalents/gO
The resulting piperazine-modified polymer was dissolved in dis-tilled water, and filtered on a microfilter to form a 2% by weight aqueous so:LutionO The polysulfone porous membrane obtained in Example 1, (A~ was dlpped for 5 minutes in the aqueous solution, withdrawn from i-t after a lapse of the 5-minute period, and drained for 10 minutes w~ile it was caused to stand perpendicularlyO
~he drained membrane was dipped for 5 minutes at room temperature in a lo 5% n-hexane solution of a 5:1 (by weight) mixture of isophthaloyl chloride and trimesoyl chloride as a crosslinking agent, then with-drawn~ and drained for 1 minute in the air to volatilize -the n~hexane adhering to the surface of the membraneO
~5 The resulting compositc membrane was subjected to the reverse osmosis test using a 00 5% aqueous NaC1 solution at a pH of 6 to 605 and a chlorine concentration ~s~o~

of 5 ppm at an operating pressure of 4205 kg/cm2~G at 25C~ The composite membrane showed initial properties represented by a water flux of 58 liters/m2hr and a salt rejection of 9204%o ~hen the reverse osmosis was continued for 900 hours at a chlorine concentration of 4 to 5 ppm and a pH of 6 to 605~ the water flux was 51 li-ters/m2ohr and the salt rejection was 9301%~ showing very stable properties (the coefficient of compaction:
-00019)o ~E~ _ s 20 to 22~
The procedure of ~xample 19 was repeated except that 2~5--dimethylpiperazine~ 2-methylpiperazine or lj3-dipiperidylpropane was used instead of the piperazine used in Example 19 and reacted in the amounts shown in Table 4 with 902 g of the maleic anhydride/me-thyl acrylate copolymer ob-tained in Example 19~ ~ach of the resulting amine-modified polymers was made into a composite membrane and subjected to the reverse osmosis -test in -the same way as in ~.xample 190 ~1he initial properties shown in Tablc 4 were obtainedO

i2~3 ~2 -Table _ ~
xample Polyamino compound Amount Amine Inlt,~ =
charged equiva- ties in reverse ( ) lel1t of osmosis g amine- _ __ modified Wa-ter Salt polymer flux rejec-(meq./g) r Q/m2.hr~ tion 20 ~
H~~~J~HH3 11. 4 2, 9 49 . 5 90 . &

21 ~N NH 10,0 3 . O 51. 7 92 . 8 2~ N~ z~ NU ~1 0 L 2.~ ~5.9 91 7 _yO~9~
A composite rllembrane was obtained by modlfying and cl~osslinking a methyl acrylate/maleic anhyclrj.de copolymer in the same way as in ~xample 1 except that isopllthaloyl chloride or trimesoyl chloride alone was used instead o~ the mixture o~ isophthaloyl chlori.de ancl trirnesoyl chloride as a crosslin~ing agent, and pipe:razine, N,M'-dimethylethylenediamine, ~ dimethyl-metaphlenylenedi~line~ or N,~ t ~dime-thyldiethyle-ne~ri.amine was used as the polyamino compound. The initial properties of the resulting composite membranes in reverse osmosis we--e as shown in Table 5, ~ ~ ~ __ ~x~nple Polyamino compound Cross- Initial properties linking in reverse osmosis agent ~ _ Water fl~x Salt (~/m2.ll~) rejec~
__ _ ~ ~ _ 23 ~ ~ /h~I IPC* ~7.4 gL~ ~ 5 __ ~ ____ ~ __, ~4 HN ~l TMC* 78.3 89.7 . ~ ~ _, IPC 29.3 91.6 C~l.\~CH2CII2I~-IC1~3 ~IC 53O2 87.4 __ ~ ~
~6 C:H3`.~ HCFl3 IPC 21~7 93.3 ~ ~IC 35~9 90.3 .___ _~ ~ _, 27 C~N~(C~2c~2~H)2c~2ct~2 IPC L~3 . ~ 91. 8 . ~ ~ ~C 63.9 90.2 _, ~_ le 28 7.7 g Of the poly(l~J,N-d:imethacrylamide) obtained in exainple 10 was put into a solution o~ 8.6 g of pipera-zi.ne in 100 ml of distillecl water, and they were reacted at 50C for 2 hours to form a uniform aqueous solution.
The a~ueous solution was purified by dialysis in ~he same way as in ~xample 19, and then water was evaporated to afford 10.5 g of an amine-modifiecl polymer o~ tlle following structure, f 3 3 CH~-C~CH2-C
o=C O=C

( ) ~he amine e~uivalent of the modified polymer was 3~9 milliequivalents/g~ ~he amine-modified polymer so :

obta.necl was di~solvecl in distilled water, and filtered to a~forcl a 2% aqueous solu-tion. Using the aqueous solution, a composite membrane was prepared in the same way as in ~,xample 19. T'ile composi-te membrane was sub-jec-ted to ~le reverse osmosis test, and was found -to have a wa-ter flux of 137 litersJm2 hr and a salt rejection of 2, 3(,~
a~
Distilled sulfonyl chloride (150 ml) was put ,.nto a 500 ml. three-neched flask equipped with a dropping fu~ne:L and a reflux condenser, and while s-tirring -the ma-l;erial ~ 20 g Of polymethacrylic acid ta number average mo.l.ecular weig11t 100,000) was ad.ded dropwise from -the clro1.-)ping funnel over the course of 2 hours. After ~.?.e addition, the temperature of the inside of the flask was raised to 50-60C, and the mixture was s-tirred further for 3 hours. ~us, the reaction mix-ture became a ~miform solu-tion~ Reinoval of tlle sulfonyl cllloride by di,stilla-ti.on a~forded poly(meth~cryloyl chloride~ a~ a reddish bro~ . solid. A 200 ml flask was charged with lOO ml of di.s~:i.lled water an~ 8,6 g of piperazinc, and after com-plete:Ly dissolving the piperazine by stirring, 4.4 g of the resulting poly(~ethac.ryloyl chlorlde) w~s added, an.d -~le mixture was stirred a-t room -tempera-ture for 1 hour.
~l.e resulting aqueous solution of piperazine-mod~ iecl poly~methacryloyl. chloride) was filtered, and 50 ml of d.iet~yl ether was added to precipitate the piperazine-moc~ ied polymer. rne amine equivalent o the polymer was 4,~ rnilliequivalents/g.
'~e pol~ner was dissolved i~ distilled wa-ter to ~o~n a 2% aqueous solu-tion. A composite membrane was .
prepQred in the same way as in Example 1 using the aqueous so:l.ution~ '~ne composi-te membrane was subjec-ted -to tke reverse osmosis -test~ and found to have i-nitial properties represented by a water flwY~ of 47.3 liters/m2 kr and a salt re.Jection of 92,5%.

5;~
-~ 75 ~

An ercess of chlorosulfonic aci.d was added at 0C -to a solution of polysulfone ~.Udel-3500 a product of Un:i.on Carbide Corporation) in chloroform to for~ chloro-sulPonated polysulfone (-the degree of chlorosulfonation 75,S).
Two grams of the chlorosulfonated polysulfone was added to a 10,b by weight aqueous solution of pipera-zine in 100 ml of distilled water. me mixture was sti.r:red at 50C for 15 hours to afford a milk-white emulsion. ~le emulsion was filterecl, and dialyzecl to foirm an emulsion of modified polysulfone containing 1.5 m~ Llequivalents/g of a recurring structural unit of the fol.~lowing formula:
cr~I
t o4~ so2~_o~_c~3~
SO

~1 .

The concentration of -this emulsion was adjus-ted to :L~) by weigh-t, and using the emulsion, a composite membr~1e was prepared in the same way as in Example 1.
Tlle co~posite membrane had a water flux of 21.7 ll-ters/
m27-.r and a salt rejection of 90.0~j~. No ch~nge in these properties was seen even after it was subjected continu-ousl~-to the reverse osmosis test in a sodium chloride solu~ion ~or 500 hours ~m~2~L
Two grams of para-chlorocarbonyl polystyrene of tlle formula ~ 2C~I
~) COC~

~ 76 _ was acldecl to ~ a~ueous solution obtained by dissolving 10 g of 2,5-dimethylpiperazine in 100 ml of distilled wate:r, and they were reacted at 15 -to 10C for 5 h~ours to af~ord an emulsion containing 1.8 milliequivalents/g of a pol~ner llaving -the following structural ~it~
4 C~C~
~3 =O
l NJ

Using a 1~ by weight emulsion o~ the polymer, a composite membrane was prepared in the same way as in Exanple 1, and subjectecl to the reverse osmosis test.
It was found to have a water flu~ of 35.2 liters/m~hr and a salt rejection of 94,7%.

Methyl acrylate (7 g ) and 3 g of sodium me-tha-llylsulfQnate were d.issolvecl in 50 ml of a mi.xture o~
water and met11anol (1:1 by weight), and in the p~e,sence o~ 0.3 g o:E potassium persulfate, were polymerized at 60C ~or 7 hours to ~orm a pol~ner containing a s-tructural un:it o~ -the ~ollowing :~ormula:
CH~
t C~2C~ CH
C=O C~2 oc~3 S2~a The lon-exchange capacity o~ this polymer was 0.95 milli-equivalent/g.
Five grams of the pol~mer was suspended in me-W!y~.ene chloricle, and 100 ml of sulfonyl chloride was added. The mixture was heated at 60 to 70C for ~, ho~rs to a~ord a polymer having a structural ~u~it o~ the following ~o~nula:

CI~3 ~2C~ ~C1~2YC
C=O C~2 o~ S03C~

Subsequently, 2 g of this polymer was added to 100 g of a 10% aqueous solu-tion of 1`\! ,M'-dime-thyl-ethvlenediamine~ and reacted at 50C for 10 hours to af:~ord a polymer containing 0.71 milliequivalen-t/g of a structural unit of the following formula-CII
C112CII ~ C~2 - C
C=O CH2 ' C~2C~I2~ N-C~3 C~13 CH2C~2~C~

One gr~n o~ this polymer was dissolved irl 100 ml of a mixture of water and ethanol (1:1 by weight)~ and '10 using tl~e solu-tion, a composi-te membrane was prepared in -~e same way as in ~xample 1. ~le composite membrane had a water flux of 59.7 liters/m2 hr and a sal-t rejectior of` ~7.~5'J~

A 500 ml three-necked round-bottomed fLas equipped with a stirrer, a thermometer and a refl~c con~enser was charged with 80 ml of dried and distilled benzeIle~ 8,6 g of maleic anhydride recrystallized from chloroform, and eacl~ of the comonomers shown in 'I'a~le 6.
rne inside o~ the ~lask was purged with nitrogen, and in a sealed condition, the temperature of the inside o~ ~he f'lask was raised -to 70C. T~e mixture was stirrecl for 8 hOllrS to precipitate a viscous pol~ner. rne polymer was well washecl with a~lyclrous benzene, and driecl at, 50C
~ der reduced pressure to af~ord a white viscous solid .. ., . . .. , ~

~ ' L5~8 - 7~
pol~er ln a yield of ~0 -to ~5~,h. I~ and ~ analyses o~
the polymer sl~owecl that it was a 1:1 copolymer of maleic anl~$rcl~ide and the comonomer.
A ~00 ml flasli was charged with each of the pol~J~nines indicated in Table 6 9 100 ml of ~T-methylpyrroli-do,-ne, and 10 g of the above copolymer. The inside of the ~lasl.r was purged Wit'tl nitrogen9 and its temperature was raisecl to 50C. The mixture was stirred for 3 hours to fo~.l an amine-modified polymer. The modified polymer solut70n was dialyzed with a cellophane membrane to remove the e~r~cess of unreacted polyamine and N-methylpyrrolidoneg an(1 -then water was evaPorated under reducecl pressure to af::~ord a pale yellow solid.
The resulting amine~modi~ied polymer was dis~olved in distilled water, ancl filtered on a microfilter to ~'o.~n an aqueous solution having each of -the concentra+,ions sho~rn in Table 6 5 and then the acid accepptor sho~n in Tab:le S was added.
The polysul~one porous membra~e obtainecl in ~ c~nple 1, (~) was dipped for 5 minut~s in t'lliS RqUeOUS
solut:iorl, then wi-thdrawn from it, and drained -For 10 mi.mltes while i-t was allowed to stand perpendicularly.
The drairlecl membr~l~ was dipped for 5 m~ utes at room tempera-ture in an n-hexane solution of each of t!le crossl:inl~ing agen-ts indicated in Table 6, wi-thdrawn, and then drained in the air :~or 1 minute to volatilize the n~l~exane adhering to -the surface o~ the membrane.
~-.e membrane was then heat-treated for 10 minutes in a hot a.ir dryer at 115 to 120C.
The resulting composite membrane was subjected to the reverse osmosis test at 25C ancl 42,5 kg/cm2~G
using a 0~5% aqueous NaCl solution. The initial pro-pert:i.ers obtained o~ the composite membrane are sl~.own in Tal~le 1.
~5 The msmbrane was subsequently tested continuous-ly ~o.r 20 hours, and t'ne coefficient of compaction obtained is also sho~n~ in Table 6.

, __ '~r, o ~o a~) o ~

~o ~ cO ~ r~
~, ~ ~ o ~ Lr~
~ ~ _ , ,~ rl ~ ~- ~D ~ ~ CO 00 ~!
E; ~ E~ 1~ 1~ ~ ~ ~ ~
H +~ O 3 tH--~ , ~ __ ,_ ~ 0 ~ _ H `-- ~` 11~\ ~ V O C O ~_~
~ ~1 ~D ~a)' ~1 E-l I ~ .. _ ~, . __ ~
~ o I H a~ ~ O ~ O O . O v ~ ''d ~\i o ~i ~i _ ~ o~
O htH ~ O O ~;
~ 0 ~d El ~ _ __ ~,` *
o ~ ~ ~O
t-l ~ ~ -- ~1 _ -- ~I~ ~ --~o~lO ~ . ~ _ _~ ~

_

Claims (39)

WHAT WE CLAIM IS:

1. A semipermeable composite membrane comprising a thin semipermeable film of a polymeric material deposited on one side of a microporous substrate, said polymeric material being prepared by crosslinking a soluble polymer containing at least 30 mole% of a recurring unit of the formula (I) wherein Q represents an organic radical containing 2 to 30 carbon atoms and having a valence of (3 + p) which optionally contains a heteroatom selected from the group consisting of oxygen, sulfur, nitrogen and halogen atoms, Y is bonded to the carbon atom in group Q
and represents a direct bond, an alkylene group containing 1 to 3 carbon. atoms or an unsubsti-tuted or substituted phenylene group;

Z represents or -SO2-;
R1 represents a hydrogen atom, or a mono-valent organic radical containing 1 to 20 carbon atoms which may contain an amino group containing 1 to 2 active hydrogen atoms and a heteroatom selected from the group consisting of oxygen, nitrogen and halogen atoms 3 R2 represents an amino group containing 1 to 2 active hydrogen atoms or a monovalent organic radical containing 1 to 20 carbon atoms contains at least one amino group containing 1 to 2 active hydrogen atoms and may contain a heteroatom selected from the group consisting of oxygen, nitrogen and halogen atoms;

R1 and R2, together with the nitrogen atom to which they are bonded may represent a 5- to 18-membered nitrogen-containing heterocyclic ring which contains a-t least one amino group having one active hydrogen atom 9 when group Y represents a direct bond and group Z represents , R1 may represent bonded to that carbon atom of the group Q which is bonded, either directly or through 1 or 2 carbon atoms, to the carbon atom to which the group Y is bonded;
p is 0, 1 or 2; and when p is 1 or 2, L represents the group in which W represents a direct bond or an alkylene group containing 1 to 3 carbon atoms and Z, R1 and R2 are as defined above, and having at least 0.2 milliequivalent, per gram of said polymer, of an amino group containing 1 or 2 active hydrogen atoms, with a polyfunctional compound containing at least two functional groups capable of reacting with the amino group having 1 or 2 active hydrogen atoms.

2. The membrane of claim 1 wherein said polymer contains at least 50 mole% of the recurring unit of formula (I),

3. The membrane of claim 1 wherein said recurring unit is represents by the formula (I-a) (I-a) wherein R3 represents a hydrogen atom or an alkyl group containing 1 to 5 carbon atoms;
R4 and R5, independently from each other, represent a hydrogen atom, an alkyl group containing 1 to 5 carbon atoms, or the group ,-NH-R6, -R7-COOR8, -O-R81, or -O-R82-X', in which R6 represents a hydrogen atom or an alkyl group containing 1 to 5 carbon atoms, R7 represents a direct bond or an alkylene group containing 1 to 3 carbon atoms, R8 represents a hydrogen atom, an alkali metal, a quaternary ammonium salt radical or an alkyl group containing 1 to 5 carbon atoms, R81 represents an alkyl group containing 1 to 5 carbon atoms, R82 represents an alkylene group containing 1 to 4 carbon atoms, and X' represents chlorine or bromine; W, Y, Z, R1 and R2 are as defined hereinabove; and a and b, indepen-dently from each other, are O or 1; or the following formula (I-b) ( I-b) wherein E represents a hydrogen atom or the group , and Rl and R2 are as defined hereinabove.

4. The membrane of claim 1 wherein said recurring unit is represented by the following formula (I-c) (I-c) wherein R9 represents a direct bond or the group U represents -O-, -CH2- or G1 and G2, independently from each other, represent a halogen atom, an alkyl group containing 1 to 3 carbon atoms, a haloalkyl group containing 1 to 3 carbon atoms or the group ;

c, d and e, independently from each other are 0 or 1;
G3 and G4, independently from each other, represent a halogen atom,an alkyl group containing 1 to 3 carbon atoms, or a haloalkyl group containing 1 to 3 carbon atoms;
f and g, independently from each other, are integers of 0 to 2; and W, Z, R1 and R2 are as defined hereinabove.

5. The membrane of claim 1 wherein Y represents a direct bond, a methylene group or a phenylene group of the formula in which R10 represents a hydrogen atom, -COOH, -SO3H, , or .

6. The membrane of claim 4 wherein W represents a direct bond or a methylene group.

7. The membrane of claim 1 wherein Z is .

8. The membrane of claim 1 wherein group represents a monovalent substituted amino group resulting from the removal of one active hydrogen atom from one of the amino groups of a polyamino compound containing at least two amino groups with 1 or 2 active hydrogen atoms.

9. The membrane of claim 1 wherein R1 represents a hydrogen atom, or an alkyl, cycloalkyl, aryl, aralkyl or heterocyclic group containing 1 to 20 carbon atoms which may contain 1 to 8 heteroatoms or heteroatom-containing atomic groupings selected from the group consisting of halogen atoms, hydroxyl groups, cyano groups, carboxyl groups, alkoxycarbonyl groups with the alkyl moiety containing 1 to 4 carbon atoms, primary amino groups (-NH2-), ether linkages (-O-), imino linkages (-NH-) and tertiary amino linkages (-?-); R2 represents a primary amino group, a secondary amino group mono-substituted by an alkyl group containing 1 to 5 carbon atoms, or an alkyl, cycloalkyl, aryl, aralkyl or hetero-cyclic group containing 1 to 20 carbon atoms which contains 1 to 10 primary amino groups or imino linkages and may contain 1 to 9 heteroatoms or heteroatom-containing atomic groupings selected from the group consisting of halogen atoms, hydroxyl groups, cyano groups, carboxyl groups alkoxycarbonyl groups with the alkyl moiety con-taining 1 to 5 carbon atoms, ether linkages are tertiary amino linkages (-?-); or R1 and R2. together with the nitrogen atom to which they are bonded, may represent a 5- to 18-membered heterocyclic ring which contains at least one amino group having one active hydrogen atom and may contain 1 to 4 nitrogen or oxygen atoms as hetero-atoms.

10. The membrane of claim 1 wherein said recurring unit is represented by the following formula (I-d) (I-d) wherein R11 and R12, independently from each other, represent a hydrogen atom or a methyl group;

R13 represents a primary amino group, a seconda-ry amino group, a secondary amino group mono-substituted by an alkyl group containing 1 to 5 carbon atoms, or an alkyl, cycloalkyl, aryl, aralkyl or heterocyclic group containing l to 20 carbon atoms which contains l to 10 primary amino groups or imino linkages and may contain 1 to 9 heteroatoms or heteroatom-containing atomic groupings selected from the group consisting of halogen atoms, hydroxyl groups, cyano groups, carboxyl groups, alkoxycarbonyl groups with the alkyl moiety containing 1 to 5 carbon atoms, ether linkages and tertiary amino lin-kages (-?-); and h is 0 or 1.

11. The membrane of claim 3 wherein said recurring unit is represented by the following formula (I-a-1) wherein R301 represents a hydrogen atom or a methyl group;
R401 and R501, independently from each other, represent a hydrogen atom, a methyl group, , -COOR801, -OR801, in which X
is chlorine or bromine, or -CH2-COOR801;
Y1 represents a direct bond, a methylene group or a phenylene group of the formula in which R10 represents a hydrogen atom, -COOH, -SO3H, , or Z represents or -SO2-;
R101 represents a hydrogen atom,an alkyl, cycloalkyl, aryl, aralkyl or heterocyclic group containing l to 12 carbon atoms which may contain l to 8 heteroatoms or heteroatom-containing atomic groupings selected from the group consisting of halogen atoms, hydroxyl groups cyano groups, carboxyl groups, alkoxycarbonyl groups with the alkyl moiety containing l to 5 carbon atoms, primary amino groups (-NH2), ether linkages (-O-), imino linkages (-NH-), and tertiary amino linkages (-?-);
R20l represents a primary amino group, a secon-dary amino group monosubstituted by an alkyl group containing l to 5 carbon atoms, or an alkyl, cycloalkyl, aryl, aralkyl or heterocyclic group containing l to 12 carbon atoms which contains 1 to 6 primary amino groups or imino linkages and may contain l to 6 heteroatoms or heteroatomscontaining atomic groupings selected from the group consisting of halogen atoms, hydroxyl group, cyano groups, carboxyl groups, alkoxycarbonyl groups with the alkyl moiety containing l to 5 carbon atoms, ether linkages and tertiary amino linkages (-?-);
R101 and R201, together with the nitrogen atom to which they are bonded, may represent a 5- to 6-membered nitrogen-containing heterocyclic ring which contains at least one amino group having one active hydrogen atom and may contain 1 to 2 nitrogen or oxygen atoms as heteroatoms;
R80l represents a hydrogen atom or an alkyl group containing l to 3 carbon atoms; and a and b, independently from each other, are 0 or 1.

12 The membrane of claim 8 wherein said polyamino compound is a compound expressed by the following formula A1-NH-A2-NH-A3 (II-a) (II-b) (II-c) (II-d) or II-e wherein Al and A3, independently from each other, represent a hydrogen atom or a lower alkyl group; A2 represents an alkylene group having 1 to 10 carbon atoms which may contain an ether linkage; A4 and A5, independently from each other, represent a hydrogen atom or a lower alkyl group optionally substituted with a cyano, hydroxyl or lower alkoxycarbonyl group; A6 represents a hydrogen atom or a group of the formula -CH2-CH2-NH-A4; A7 represents a lower alkylene group; A8 represents a hydrogen atom or a lower alkyl group optionally substituted with a cyano, hydroxyl or lower alkoxycarbonyl group; A9 represents a lower alkylene group; at least one of A10, A11 and A12 represents a lower alkyl group, and the remainder represent a hydrogen atom; and i is an integer of 2 to 6.

13. The membrane of claim 1 wherein said polymer is a polymer consisting essentially of the recurring unit I alone.

14. The membrane of claim 3 or 10 wherein said polymer is a copolymer composed of the recurring unit of formula I-a, I-b or I-d and at least one other recurring unit derived from a radical polymerizable monomer.

15. The membrane of claim 3 or 10 wherein said polymer is a copolymer composed of the recurring unit of formula I-a, I-b or I-d and at least one other recurring unit derived from a radical polymerizable monomer, and wherein said radical polymerizable monomer is a compound containing one or two ethylen-ically unsaturated bonds.

16. The membrane of claim 3 or 10 wherein said polymer is a copolymer composed of the recurring unit of formula I-a, I-b or I-d and at least one other recurring unit derived from a radical polymerizable monomer, and wherein said radical polymerizable monomer is a compound containing one or two ethylen-ically unsaturated bonds and containing 2 to 15 carbon atoms.

17. The membrane of claim 3 or 10 wherein said polymer is a copolymer composed of the recurring unit of formula I-a, I-b or I-d and at least one other recurring unit derived from a radical polymerizable monomer, and wherein said radical polymerizable monomer is a compound containing one or two ethylen-ically unsaturated bonds and having a molecular weight of 28 to 300.

18. The membrane of claim 3 or 10 wherein said polymer is a copolymer composed of the recurring unit of formula I-a, I-b or I-d and at least one other recurring unit derived from a radical polymerizable monomer, and wherein said radical polymerizable monomer is a compound containing one or two ethylen-ically unsaturated bonds and which has a solubility of at least 0.5 g at 25°C
in l00 g of water or a lower alcohol.

19. The membrane of claim 3 or 10 wherein said polymer is a copolymer composed of the recurring unit of formula I-a, I-b or I-d and at least one other recurring unit derived from a radical polymerizable monomer, and wherein said monomer is a compound represented by the following formula III-l III-l wherein R14 represents a hydrogen atom or an alkoxycarbonyl group with the alkyl moiety containing 1 to 10 carbon atoms; R15 represents a hydrogen or halogen atom or a methyl group; R16 represents a hydrogen or halogen atom, an alkoxy group containing 1 to 10 carbon atoms optionally substituted by a hydroxyl group and/or a halogen atom, an alkoxycarbonyl group with the alkyl moiety containing 1 to 10 carbon atoms, an alkanoyl group containing 1 to 10 carbon atoms, an alkanoyloxy group containing 1 to 10 carbon atoms, an alkyl group containing 1 to 10 carbon atoms substituted by the group -SO3M or hydroxyl group, a phenyl group optionally substituted by the group -SO3M or a methyl group, a glycidyloxy group, or a group of the formula (-B-O-)jH in which B represents an ethylene or propylene group, and j is an integer of 1 to 8; R14 and R15, together, may represent an ethylenedioxy group; and M represents an alkali metal; or the following formula wherein R17 and R18, independently from each other, represent a hydrogen atom or a methyl group;
J represents an oxygen atom or a group of the formula R19 and R20, independently from each other, represent a hydrogen atom or an alkyl group containing 1 to 10 carbon atoms; and represents an anion.

20. The membrane of claim 3 or 10 wherein said polymer is a copolymer composed of (A) at least 50 mole% of the recurring unit of formula (I-a), (I-b) or (I-d), and (B) up to 50 mole% of at least one recurring units selected from those of the formulae (IV-l) wherein R21 represents a hydrogen atom or an alkoxy-carbonyl group with the alkyl moiety containing 1 to 10 carbon atoms;
R22 represents a hydrogen or halogen atom or a methyl group;
R23 represents a hydrogen or halogen atom, an alkoxy group containing 1 to 10 carbon atoms optionally mono- or di-substituted by a hydroxyl group and/or a halogen atom, an alkoxycarbonyl group with the alkyl moiety containing 1 to 10 carbon atoms, an alkanoyl group containing 1 to 10 carbon atoms, an alkanoyloxy group containing 1 to 10 carbon atoms, an alkyl group containing 1 to 10 carbon atoms which may be mono-substituted by the group -SO3M or a hydro-oxy group, a phenyl group optionally mon-sub-stituted by the group -SO3M or a methyl group, a glycidyloxy group, a group of the formula (-B-O-)jH in which B represents an ethylene or propylene group and j is an integer of 1 to 8, the group , the group , in which Rl and R2 are defined hereinabove;
R21 and R22 together may represent an ethylenedioxy group;
R22 and R23 together may represent ;
and M represents an alkali metal; and (IV 2) wherein R17, R18 and J are as defined with regard to formula (III-a), and R24 represents a direct bond or -SO2-.

21. The membrane of claim 1 wherein said polymer as a solubility of at least 0.1 g at 25°C in 100 g of water or a water-miscible polar organic solvent.

22. The membrane of claim 1 wherein said polymer has a solubility of at least 0.5 g at 25°C in 100 g of water or a water-miscible polar organic solvent.

23. The membrane of claim 21 or 22 wherein said organic solvent is selected from the group consisting of lower alcohols, formic acid dimethylformamide, dimethyl-sulfoxide, tetramethylenesulfone and N-methylpyrrolidone.

24. The membrane of claim 1 wherein said polymer has an inherent viscosity, determined at 30°C in the solvent of claims 22 or 23 with 0.5% by weight of the polymer solution, of at least 0.1 dl/g.

25. The membrane of claim l wherein said polymer has an inherent viscos-ity, determined at 30°C in the solvent of claims 22 or 23 with 0.5% by weight of the polymer solution, of 0.15 to 5.0 dl/g.

26. The membrane of claim 1 wherein said polyfunctional compound is a polyfunctional compound containing at least two functional groups selected from acid halide, sulfonyl halide, isocyanate, N-haloformyl, haloformate and acid anhydride groups, or cycnuric chloride.

27. The membrane of claim 1 wherein the polyfunctional compound is an aromatic, heterocyclic or alicyclic compound.

28. The membrane of claim 1 wherein the polyfunctional compound is an aromatic compound.

29. The membrane of claim 1 wherein the polyfunctional compound is a di-or tri-functional aromatic compound containing two or three functional groups selected from acid halide, sulfonyl halide and acid anhydride groups.

30. The membrane of claim 1 wherein the polyfunctional compound is a di-functional aromatic compound containing two isocyanate groups.

31. The membrane of claim 1 wherein the polyfunctional compound is a tri-functional aromatic compound, or a mixture of a difunctional aromatic compound and a trifunctional aromatic compound.

32. The membrane of claim 31 wherein the di- or tri-functional aromatic compound is isophthaloyl chloride, terephthaloyl chloride, trimesoyl chloride, 3-chlorosulfonylisophthaloyl chloride, or cyanuric acid chloride.

33. The membrane of claim 1 wherein said thin semipermeable film has a thickness of at least about 100 .ANG..

34. The membrane of claim 1 wherein said microporous substrate is composed of an asymmetrical membrane of an aromatic polysulfone.

35. A process for producing a semipermeable composite membrane which com-prises (a) treating a microporous substrate with a solution containing a soluble polymer containing at least 30 mole % of a recurring unit of formula I

I

wherein Q represents an organic radical containing 2 to 30 carbon atoms and having a valence of (3 + p) which may contain a heteroatom selected from the group consisting of oxygen, sulfur, nitrogen and halogen atoms; Y is bonded to the carbon atom in group Q and represents a direct bond, an alkylene group con-taining 1 to 3 carbon atoms or an unsubstituted or substituted phenylene group;
Z represents or -SO2-; Rl represents a hydrogen atom, or a monovalent organic radical containing 1 to 20 carbon atoms which may contain an amino group containing 1 to 2 active hydrogen atoms and a heteroatom selected from the group consisting of oxygen, nitrogen and halogen atoms; R2 represents an amino group containing 1 to 2 active hydrogen atoms or a monovalent organic radical con-taining 1 to 20 carbon atoms which contains at least one amino group containing 1 to 2 active hydrogen atoms and may contain a heteroatom selected from the group consisting of oxygen, nitrogen and halogen atoms; R1 and R2, together with the nitrogen atom to which they are bonded may represent a 5- to 18-membered nitro-gen-containing heterocyclic ring which contains at least one amino group having one active hydrogen atom; when group Y represents a direct bond and group Z
represents , Rl may represent bonded to that carbon atom of the group Q

which is bonded, either directly or through 1 or 2 carbon atoms, to the carbon atom to which the group Y is bonded; P is 0, 1 or 2; and when p is 1 or 2, L

represents the group in which W represents a direct bond or an alkylene group containing 1 to 3 carbon atoms and Z, R1 and R2 are as defined above, and having at least 0.2 milliequivalent, per gram of said polymer of an amino group containing 1 or 2 active hydrogen atoms, and (b) contacting the treated microporous substrate interfacially with a solution of a polyfunctional compound containing at least two functional groups capable of reacting with the amino groups having one or two active hydrogen atoms, to form a thin film of the crosslinked polymer having semi-permeability on one side of the microporous substrate.

36. The process of claim 35 wherein the treated microporous substrate and solution of polyfunctional compound are heated to form the thin film of cross-linked polymer having semipermeability on one side of the microporous substrate.

37. The process of claim 35 or 36 wherein the resulting composite membrane is coated with a water-soluble organic polymer.

38. The process of claim 35 or 36 wherein the resulting composite membrane is coated with a water-soluble organic polymer, which is polyvinyl alcohol, polyvinyl pyrrolidone or polyvinyl methyl ether.

39. In a method for desalination of saline or brackish water by reverse osmosis comprising contacting the saline or brackish water under pressure with a reverse osmosis membrane, the improvement wherein the membrane of claim 1 is used as the reverse osmosis membrane.