CA2174629A1

CA2174629A1 - Alumina thickened latex formulations

Info

Publication number: CA2174629A1
Application number: CA002174629A
Authority: CA
Inventors: Curtis M. Elsik; Ronald L. Beggs
Original assignee: Individual
Current assignee: Sasol North America Inc
Priority date: 1993-10-21
Filing date: 1994-09-02
Publication date: 1995-04-27
Also published as: EP0728157A1; DE69427828D1; US5550180A; JP3507901B2; DE69427828T2; EP0728157B1; EP0728157A4; JPH09511258A; WO1995011270A1

Abstract

A latex composition comprising, as a rheology modifier, an effective amount of a boehmite alumina having a crystal size (020 plane) of less than about 60 Angstroms and a surface area, when calcined to gamma phase, of greater than approximately 200 m2/g, the boehmite alumina being present in an amount effective to obtain the desired rheological properties of the composition.

Description

2 ~ 7 ~ b 2 3 PCT/US94/09878 ALUMINA THICKENED LATEX FORMULATIONS
Back~lv. ~1 of the Invention -1. Field of the I~
The present invention relates to thic~PnP~ latex compositions and, more particularly, thickened latex paint coll,posilions.

2. De~,cription of the Prior Art Water-based latex paints and co~ g~ (latex compositions) are widely used in industrial and resid~Pnti~l appli~til n~. In order to pclÇOllll pr~pelly, these latex compositions must be able to be applied unifo~lllly to horizontal (top and bottom), vertical, and even intricately shaped objects with a minimum tçn~çncy to run. Such pe,rorlllallce requires rheology control during and after appli~tion of the latex col,lposilions. Typically, latex colllpositions can be applied by one of severalmethods, including spraying, brushing or applying by means of a roller.
Accordingly, rheology control of the compositions must be such as to allow ~lt~-.rn~t~
methods of application. Additionally, since the formulations are all su~pçn~ions of solids, e.g., pigm~nt~, in liquid, the rheology must be controlled during production as well as during storage to prevent undue settling and separation of the colll~nents of the formulation.
It is well known that organic thi~k~ners such as hydroxyethyl cellulose (HEC) can be used to thicken water-based latex compositions. Additionally, certain clays that are known to act as thixotropes in water solutions are also used, alone or in conjunction with HEC, as thickPning agents. More recently, there have been developed what are known as "Associative Thi~kt~ners," which are generally synthetic polymeric materials dispersed in water-colllpatible (-miscible) liquids.
It is well known that monohydrated aluminas, e.g., boçhmite ~lnmin~c, can be used as thickeners for simple aqueous solutions. For example, the prior art discloses the use of such boehmite aluminas as thickeners in aqueous cleaning formulations.

WO 95/11270 2 17 ~ 6 2 9 PCTtUS94tO9878 Sllm~qry of the Invention It is therefore an object of the present invention to provide a thickened, water-based latex composition employing an alumina thickPning agent that exhibits shear thinning .
5Still a further object of the present invention is to provide a water-based latex paint composition that exhibits superior clean-up p,opellies.
The above and other objects of the present invention will become a~ ~ent from the drawings, the description given herein and the appended claims.
The present invention provides a thickened latex composition comprising, as 10a rheology modifier, a boehmite ~lumin~ in an amount effective to obtain the desired rheological p~opelLies of the colllposition. The boehmite aluminas that are useful in the compositions of the present invention are those posses~ing a crystallite size (020 plane) of less than about 60 Ang~lullls and a surface area, when calcined, of greater than ay~ imately 200 mVg.

Brief D~ lion of the Drawings Fig. 1 is a Bohlin rheology graph showing the effect of various thickeners used in an Interior Quality Flat Wall Paint.
Fig. 2 is a Bohlin rheology graph showing the effect of various thickeners 5 used in a High Quality Interior Flat Paint (vinyl-acrylic).
Fig. 3 iS a Bohlin rheology graph showing the effect of various thickeners in an Exterior (modified-acrylic) Quality House Paint - White.
Fig. 4 is a Bohlin rheology graph showing the effect of various thick~n~rs in an Exterior (modified-acrylic) Quality High Build House Paint - White.
Fig. 5 is a graph showing a co-llp~ison of the thic~Pning ability of various boehmite ~ min~ versus HEC in a Good Quality Flat Wall Paint - White.

W O 9S/11270 ~ 1 7 ~ 6 2 Q PCT~US94/09878 De~,;~lion of the Preferred Elnbodilnents As noted, the present invention finds particular application to latex compositions. Such latex co"~posilions are well known to those skilled in the art.
The term "latex co",posilion," as used herein, refers to a co",posiLion in which a 5 binder comprising small globules or particles that are natural or synthetic rubber or plastic are dispersed in water. An example of such latex co"~positions are what are commonly referred to as emulsion paints or latex paints. Non-limiting examples of such synthetic rubber or plastic materials include styrene-bu~lipne rubber; polyvinyl acetate; copolymers of vinyl acetate with monomers such as butyl acrylate, octyl10 acrylate, dibutyl rwna,~le, dioctyl m~ te, vinyl propionate, etc.; and polyacrylate polymers and copolymers such as copolymers of ethyl acrylate and a suitable alkyl methacrylate. Generally spe~king, latex compositions of the type under consideration will contain from about 10% to about 90% of the latex binder or vehicle (including water) and an amount of from about 90% to about 10% by weight of other well-15 known components or ingredients such as pigmtont~, e.g., tit~nillm dioxide, calciumcarbonate, etc. Additionally, latex paint co",posilions commonly contain thickeners, surf~ct~nt~, antirreeze agents, preservatives, biocides, co~lescent aids, pH adjustors, antifoam agents, etc. Commonly, latex paints of the type under consideration will contain the pigm~nt~ in amounts of from about 10% to about 70% by weight of the 20 composition.
The boehmite ~lumin~ thickener that is useful in the thic~n~oA compositions of the present invention can comprise any boehmite alumina that has a crystal size, as measured on the 020 plane, of less than about 60 Angstroms and a surface area, when calcined to the gamma phase, of greater than approximately 200 m2/g. In 25 dele""ining the surface area of the useful boehmite alumin~, typically the boehmite alumina is calcined at a temperature of from about 450 to about 500 C for a period of time of from about 1 to about 5 hours. Such c~lcining generally converts the boehmite alumina into gamma alumina. It is to be understood, however, that when used as the thicl~np~r or rheology modifier in the compositions of the present 30 invention, the alumina is used as the boehmite form of ~lllmin~, i.e., in its uncalcined form. Generally spe~king, the boehmite ~lumin~ will be present in an amount effective to obtain the desired rheological pn~pellies of the composition. For WO 95/11270 2~1~ 4 6 ~ 9 PCT/US94/09878 example, depending upon the type and angle (relative to the horizontal) of the surface to which a latex paint is applied, the desired rheological propel lies of the composition can vary widely, and accordingly the amount of thic~n~r employed can vary widely.
Generally speaking, however, and particularly when used in a latex paint, the 5 boehmite alumina thickener will be present in an amount of from about 0.1% to about 5% by weight of the composition. It is particularly ple~lled, although not neCçs;~y~ that the boehmite ~ min~ employed be of the water-dispersible type, i.e., of a type that does not require acid for dispersibility.
To more fully illustrate the present invention, the following non-limiting 10 examples are pr~sented. In the following examples, the latex paints were prepared in a two-step manner commonly used in the commercial prep~lion of paint formulations. In the "grind" step, pi~m~nt~ and ingredients required for dispersion are added and mixed at high shear rates. In the "letdown" step, the resins and other heat- or shear-sensitive components are added and mixed at lower shear rates. In the 15 grind step, the col~ponents were combined and dispersed at approximately 2000feet/min (agitator tip speed) on a labol~to,y Cowles dissolver using a 1.5" Cowles blade. The letdown ingredients were added and blended at a lower agitator tip speed until uniformly mixed. Various viscosity measurements were made using a Brookfield Viscol"e~el or a Bohlin VOR Rheo",eler.

20 Example 1 This example shows the use of a water-dispersible ~ll)min~ as a total and partial repl~ mPnt for HEC in an Interior (modified-acrylic) Good Quality Flat Wall Paint. The formulations are shown in Table l below.

2~ 7~629 WO 95/11270 i ~ ~ PCT/US91/09878 3 ~ o o o ~`1 o o o o ~

~b V E D g.
--~ t~ ~ ~ ~ ~ -- ~ X

3 ~'i o o ~ o o o o ~

x -- ~ a~ x ~ o V V

3 ~`i o o ~`i o o o 3:

~ ~~ ~ ~ o~ ~ ~ o v ~ x ~ ~ ~ ~ ~ o æ C ~ C ~ b ~17~62g WO 95/11270 PCT/US91/05~78 o -- o -- X l~ oo o ~o ~ o -- o~ ~` o ~ o oo ~ o~ o U~ oo oo ~ o~ l` ~ o o~ o C~ ~,, _ oo ~ o~ o o ~ O -- o~
:C ~
D V
;~; x ~ ~ 8 ~ ~ = a g .~ V~ o V ~ @ 3 D

8 ~ C ~ ~ c ~

~ C ~ D ~ ~8 .~ E ~E E.~ E

;g ~ 88 ~ ô ~ 0 E ~ ~
x ~ iE ~ E

v ~ æ~ '~ O - E - ~ ~

WO 95/11270 ~! 1 7 4 6 2 9 PCT/US94/09878 Fig. 1 shows Bohlin rheology plots for the formulations of Table 1. As can be seen, the boehmite a!umina can be used to replace HEC completely or partiallyand still ~ in~ similar viscosity profiles for the overall formulation. As can also be seen, the formulations con~;.il-illg the alumina are more shear thinnable than those 5 conl~inillg only HEC. This is an i~ t factor when paint formulations are applied by means of spraying since it obviates the n~essity of having to dilute the formulations.

F.Y~ rl~ 2 This example demonsL,a~es the use of boehmite alumina as a total repl~r~m~nt 10 for a clay thickener and as a partial repl~cen ~nt for an ~oci~tive Thickener in a High Quality Interior Flat Paint (vinyl-acrylic). The formulations are shown in Table 2 below.

QR 708 + ATTAGEL 40 QR 708 + ALUMINA
Batch Size: 100 Gal. Formula 100 Gal. Formula Ingredient Lbs. w/w% Lbs. w/w%
PIGMENT GRIND
DI Water 130.0 11.34 120.0 10.53 DISPERAL SOL 8.20 0.72 Tamol 960' 10.0 0.87 10.0 0.88 Nuosept 145 2.0 0.17 2.0 0.18 Colloid 6402 2.0 0.17 2.0 0.18 AMP-95 2.0 0.17 2.0 0.18 Ti-Pure R-9003 200.0 17.45 200.0 17.55 Satintone Special4 125.0 10.91 125.0 10.97 Min-U-Sil 405 75.0 6.54 75.0 6.58 Attagel 4o6 7.0 0.61 LETDOWN O
Colloid 640 ¦4.0 ¦ 0.35 ¦4.0 ¦ 0.35 462g X o~ o ~ o X -- O~ l-- ~ O D
O ~ O O t` 00 ~ _ O O ~ O O ~ O
O ~ O O ~ C~
~ _ 8 ~

~` X ~ O d V~ Q ~ ~
X -- ~ ~ ~ ~ C~ . ...
o ~ -- -- ~,, ~ O ~ ~ ~8 o ~, D O
O

o o t-- o o. ~ o. ~ 8 O ~ `O ~ O -- ~C\ ~ ~ ^ . ~, D
E ~ + ~ o ~ D ~ ^ D

c 3 , ~ 3 ~ ~, .= o E ~ E ~ E

~ ~ ?~5 c , r ~ ?

2~7~2g Fig. 2 shows Bohlin rheology curves colllpaling the formulations of Table 2.
As can be seen, the ~hlmin~ can be used to completely replace the clay thickener and - partially replace the Associative Thic~Pner while "~ .ining similar viscosity profiles for a formulation col-l~inil-g clay thickener and Associative Thic~ner. As can S further be seen, the formulation col,~;.h-il-g the ~lumin~ exhibits better shear thinning characteristics than the formulation without any ~ min~

Example 3 This example demonstrates that boe.hmite. alumina can be used as a partial repl~.e.m.ont for HEC in an Exterior (modified-acrylic) Quality House Paint - White.
10 The formulations are shown in Table 3 below.

x~74629 wo 95/11270 2 Pcr/l~s~ 1 ~3~78 B~

o Xo z ~000 000000 '1:
+
E
o ~ C~
~a ~
V ~ ~ X _ o o~ o o o o o ~ ~ o ~ X ;o o o o ~ ~ ~ ~ ~

a~

3 ~ ` oOo xo t~
o o oooooo~i_~

-o C:~ ~ ~ -- ` o o o o o o o ~ ~ ~ ~ o _ ~ t_ ~ ~ ~ ~

--o O O ~ ~ ~ ~

e ~ O, ~ ~ O ~ 0 8 2-~74~
WO 95111270 PCTIUS94/098i8 ~'I ~ Q
o -- o o Q

X ~
oo ~I -- D cd ~i ~
. . ~
E E

E
_ o. ~ ~; 3 ~ Q
e ~ a E ~1~ D D _ ~;o E C- ~ 3 E ;~
~o ~ b i~ 8 E ~ Z ~ v Z v The Bohlin rheology plots for the formulations of Table 3 are shown in Fig.
3. As can be seen, boehmite alumina can be used to replace HEC partially and maintain viscosity profiles for the overall formulation in an exterior house paint. As can also be seen from Fig. 3, the formulation cont~ining the boehmite alumina S exhiblts enh~nced shear thinning, making it easier to apply by techniques such as spraymg.

Example 4 This example demonstrates the use of boehmite alumina as a total repl~ rnPnt for a clay thic~pnpr and a partial repl~cPTnPnt for an ~soci~tive ThickPner in an 10 Exterior (modified-acrylic) Quality High Build House Paint - White. The formulations are shown in Table 4 below.

QR-708 + ATTAGEL-50 QR-708 + ALUMINA
Batch Size: 100 Gal. Formula 100 Gal. Formula Ingredient Lbs. w/w% Lbs. w/w%
PIGMENT GRIND
DIWater 160.8 13.83 160.8 13.85 DISPERAL SOL P2 5.5 0.47 Propylene Glycol34.1 2.93 34.1 2.94 Byk VP-155 6.8 0.58 6.8 0.59 KTPP 1.0 0.09 1.0 0.09 ' Triton N-57' 1.1 0.09 1.1 0.09 ~
Colloid 640 1.0 0.09 1.0 0.09 ~3 Nuosept 145 2.0 0.17 2.0 0.17 Nuocide 96o2 7.0 0.60 7.0 0.60 Ti-Pure R-9023 225.0 19.34 225.0 19.39 Nytal 3004 100.0 8.60 100.0 8.62 Minex 7 100.0 8.60 100.0 8.62 ~D
Attagel 505 3.0 0.26 ~I

~174623 W O 95/11270 PCTrUS94/09878 g ~` o ~ -- -- o a~ o ~ -- 8 ~ V~ O X X X ~D
O
_ ~

o x _ ~ -- 8 ~ e a '' 8 :C ~ o p~

U~ o X X oo _ _ ,C ~ Y U
3~ .5 E

u W ~ -- ~; C ~ 9 ~ 8 WO 95/11270 2 1 7 4 ~ 2 9 PCT/US94/09878 Bohlin rheology curves are shown for the formulations in Table 4. As can be seen, the curves demonstrate that boehmite ~ min~ can be used to completely replace - the clay thic~n~or and partially replace the Associative Thick~ner while ~ h~inill~
similar viscosity profiles for the final formulations in an exterior archit~tll,~l paint 5 formulation.

Example 5 The physical propellies of various boehmite ~ min~ are listed in Table 5 below.

2171~29 _ ~8 --3~ ~ ~

.~
o a ~~ ~~ O

V ~ D
O ~V .a~

~ ~ . o O ~U ,~

e ~ O,~ X

X O Do D D

~174629 The boehmite aluminas listed in Table 5 were used as thickeners in a Good Quality Flat Wall Paint - White formulation. The formulations made using the alumina thickeners were colllpared with a formulation that used HEC as the thickener.
In all cases wherein the alumina thic~n.o.r was used, it was present in an amount of 5 2.7 times the amount of HEC used in the co-~j~nding formulation. The formulation in which the thicl~ner is HEC is shown in Table 6 below.

WO 9S/11270 217 4 ~ 2 g PCT/US94/09878 INGREDIENTS ¦ w%
PIGMENT GRIND
Water 27.75 Preservative' 0.20 Cellulose QP-15,000 0.42 Dis~c;,sanl2 0.31 Potassium Tripolyphosphate (KTPP) 0.17 Nonionic Surfactant3 0.17 Antifoam4 0.16 Propylene Glycol 2.38 Titanium Dioxide5 19.14 Clay6 8.51 Silica7 8.51 Silica8 2.13 LETDOWN
UCAR Acrylic 516 28.58 Coalescing Aid9 1.18 An~ifoall.4 0.16 Aml.. oniul" Hydroxide, 28% Aqueous Solution 0.15 TOTAL 100%

'NUOSEPT 145.
2"Colloid" 111 (Rhone-Poulenc) or equivalent.
3"Triton" N-101 (Union Carbide) or equivalent.
4"Patcote" 803 (Patco Specialty) or equivalent.
5"Ti-Pure" R-900 (DuPont) or equivalent.

6"Altowhite" TE (Dry Branch Knolin Co.) or equivalent.
7MIN-U-SIL 40.
8"Celite" 499 (Johns Manville) or equivalent.
9"Texanol" (F~ctm~n) or equivalent.

WO 95tll270 2 17 4 6 2 9 PCT/US94/09878 The latex paints cont~ining the various aluminas and HEC were subjected to Brookfield viscosity measurement~. The results are shown in Fig. 5. As can be seen from Fig. 5, aluminas wherein the crystallite size (020 plane) is less than about 60 Angstroms and the surface area (calcined) is greater than about 200 mZ/g show S colllp~ble or better rheology characteristics than HEC. In particular, note that aluminas wherein the crystallite size (020 plane) is less than about 40 Angstroms and the surface area (when c~lcin~d to the gamma phase) is greater than about 250 mVg show superior rheological pr~pelLies as colllpa,~;d to HEC, albeit at a higher loading.
Although as shown in Fig. S the required loading of the boehmite alumina 10 thickeners is signific~ntly larger than that of HEC in a co,llpal~ble latex paint, the other benefits achieved by using boehlllile ~lumin~ as colllpar~d with HEC offset this loading dirr~l~nlial. It has been found that latex paints made using boehmite min~, even as partial thickener replacemPnt~, are much easier to clean up than latex paints conl~ining only HEC, clays or ~ re Thi~n~ors. It is also believed 15 that, unlike HEC and some Associative Thickeners, boehmite alumina thickeners are not subject to biodegradability. As demonstrated above, the incol~laLion of boehmite alumina in latex paints enh~nces shear thinning, p~ mably making such latex paints easier to apply with sprayers without dilution. Lastly, because of the intrinsic nature of boehll,ile ~lllmin~ as colllpa~ed to ~ tive Thicl~ton~rs or HEC, 20 latex paints employing boehmite aluminas as thir~eners are eAl)ecLed to exhibit good scrubbability, i.e., they are more durable when subjected to washing or scrubbing.
The for~going dcsclipLion and exarnples illustrate selected embo liment~ of the present invention. In light thereof, variations and m~ifi~tions will be suggested to one skilled in the art, all of which are in the spirit and purview of this invention.

Claims

What is claimed is:

1. A latex composition comprising, as a rheology modifier, a boehmite alumina having a crystallite size (020 plane) of less than about 60 Angstroms and a surface area, when calcined to gamma phase, of greater than about 200 m2/g, saidboehmite alumina being present in an amount effective to obtain the desired rheological properties of said latex composition.

2. The composition of Claim 1 wherein said latex composition comprises a latex paint.

3. The composition of Claim 2 including an additional rheology modifier.

4. The composition of Claim 3 wherein said additional rheology modifier comprises a cellulosic thickener.

5. The composition of Claim 4 wherein said additional rheology modifier comprises hydroxyethyl cellulose.

6. The composition of Claim 3 wherein said additional rheology modifier comprises an inorganic material that exhibits rheological properties in an aqueous medium.

7. The composition of Claim 6 wherein said additional rheology modifier comprises a clay.

8. The composition of Claim 3 wherein said additional rheology modifier comprises a polymeric material dispersed in a water-compatible carrier liquid.

9. The composition of Claim 1 wherein said boehmite alumina is water-dispersible.

10. The composition of Claim 1 wherein said boehmite alumina has a crystallite size of less than about 40 Angstroms and a surface area when calcined to gamma phase of greater than about 250 m2/g.

11. The composition of Claim 1 wherein said boehmite alumina is present in said composition in an amount of from about 0.1% to about 5 % by weight of said composition.