CA1131395A - Derivatives of aryl ketones and p-dialkyl- aminoarylaldehydes as visible sensitizers of photopolymerizable compositions - Google Patents

Abstract

Abstract Photopolymerizable compositions comprising a photopolymerizable monomer, an initiator, e.g., hexa-arylbiimidazole and a sensitizing amount of a selected compound derived from aryl ketones and p-dialkylamino-arylaldehydes. The photopolymerizable compositions which optionally contain inert components such as organic polymeric binders, solvents, etc. are photoactivated in the visible region of the spectrum. The photopolymeriz-able compositions are useful in lithographic and letter press printing plates, engineering drafting films, litho-graphic films, photoresists and solder masks.

Description

~i3~395 Derivatives of Aryl Ketones and p-Dialkyl-aminoarylaldehydes as Visible Sensitizers of Photopolymerizable Compositlons DESCRIPTION
Technical Fie~d This invention relates to new photopolymer-izable compositions. More particularly, this invention pertains to photopolymerizable compositions containing photodissociable initiators in combination with selected sensitizers derived from aryl ketones and p-dialkylamino-arylaldehydes that absorb in the visible region of the spectrum.
Background Art Much work has been done in the field of photo-polymerization to increase the polymerization speed ofthese compositions. Many of the well-known photoiniti-ators or photoinitiator systems used, however, limit the applicability of the photopolymerizable compositions and elements because the initiators are activatible pri-marily in the ultraviolet region of the spectrum.
Chambers U.S. Patent 3,479,185 disclosesphotopolymerizable compositons containing an ethyl-enically unsaturated monomer, a free radical producing agent such as a leuco triphenylamine dye and a hexa-arylbiimidazole. These compositions are photoinitia-i ~L~3~395 table in the ultraviolet region of the spectrum.Chambers, however, found that by adding energy-trans-fer dyes of the xanthene and acridine classes the sensi-tivity of the photopolymerizable compositions was ex-tended into the visible spectral region with an increase in speed of polymerization.
Chang U.S. Patent 3,549,367 discloses photo-polymerizable compositions containing hexaarylbiimi-dazoles and p-aminophenyl ketones, e.g., Michler's ketone, which extend the spectral sensitivity of the compositions slightly into the visible region of the spectrum. Baum and Henry U.S. Patent 3,652,275 further enhances the efficiency of the hexaarylbiimidazole systems in photopolymerizable compositions through the use of selected bis-(p-dialkylaminobenzylidene) ketone sensitizers.
While the aforementioned compositions have provided improved visible light sensitization of photo-polymerizable compositions, further improvement inphoto speed is desirable so that lower energy exposure sources can be used or the efficiency of imagewise poly-merization exposure improved. Furthermore, improved sensitization enables the exposure source to be maintained 25 at a greater distance from the photopolymerizable layer thereby allowing for greater collimation of radiation from the exposure source. It is also desirable to pro-vide improved speed of sensitization in the visible region of the spectrum particularly for use in a photo-30 polymerizable composition containing specific nitro-aromatic compounds as photoinhibitors which are capable of producing positive polymeric images by means of a double exposure process,first imagewise in the ultravio-let region of the spectru~ and then overall in the visible 35 region of the spectrum. Nitroaromatic photoinhibitors and process for producing positive polymeric images ` 11;~3~S
are disclosed ln Pazos, Belgian patent 852 517.
Di sc lo sur e of Inventi on In accordance wlth thls invention.. a photo-polymerizable composition is provlded which comprises 5 an admixture of`
(1) at least one non-gaseous ethylenically unsaturated c ompound having a boillng point above 100C.
at normal ~mospherlc pressure and being capable of forming a high molecular we~ght polymer by photoinltiated, 10 addltion polymertzat~on;

(2) at least one 2,4,5-triary7~midazolyl dimer consisting of two lophine radicals bound together by a single covalent bond; and (3~ a ~ensitlzing amount of an arylylidene aryl ketone compound Or the formulae:
A.

C~=C~

wherein: A, B, D, E are carbon atoms or one ~ay be sole:Ly a nitro~en atom;
Rl i s H, OH or CH30;
~2 is H, OH, CH30 or N(R7)2;
R3 is E, OH or CH30 a :Ls 0 or 1;
z 15~ C=,? CHOH~ C(-CH3~2' ~CH2~b' b ~8 1, 2, or 3, -O-C-, -O-~H-, -S-ÇH-, where~n R' is R~ R' I
H, phenyl, or Z is linked wlth R4 where Z is~ CH and R4 i8 -O- or~ N-CH3~ a being 0;

R4 is H, CH3, OH, CH30;
R5 is H or R5 ~ R7 i~ C~2cH2-~ -CH2cH2cH2-' O CH2CH2;
6 6 ~ R7 i~ -C~2cH2-~ -CH2CH2CH2-J
0-CH2CH2-; and ~7 i8 CH3, -(C~2)n-CH3 where n i8 1 to 5, 2 H2 Cl, -CH2CH20~, CEI2CEI20CH3;

R3 ~C-C--CH~N

4 R5 ~7 P'8 10 wherein: A, B, D are carbon atoms or one may be ~olely a nitrogen atom;
Rl is H, C~3, -OCH2CH20R, wherein R is H, CH3, -cH2cH2oRl wherein R' i~ CH3 or CH3CH2-;
R2 is H, CH3, OH, or CH30;
R3 is H, 0~, CH30, CH3, F, ~r, CN or N(X10)2;
R2 + R3 is -0-CH2-0~;
R4 is H, CH3 or CH30;
R5 1~ H, CH3, -OCH2CH20R7 whereln R is H, CH3, -CH2CH20RI whereln R' is CH3 or CH3CH2-;
R6 i~ H, CH3 or pherurl, R7 ~8 ~I~ CH3~ 0~ or CH30;
R8 ls H;
R8 t Rlo is -CH2CH2-, -CH2CH2CH2-, -0CH2CH2;
R~ 18 H, Rg ~ Rlo i~ -CH2CH2-~ -CH2CH2CH2-' 25 -OCH2CH2-; arld Rlo is CH3, ~CH2~nCH3 whexein n is 1 to 5; and "~ , ~L~31395 C. 0 R~

~ ~ CH ~ ~(R2)2 or ~ t~f~ (R2)2 wherein G is -C-, -0-, or -S-;
Rl is H, CH3 or -OCH3, and R2 is CH3 or -CH2CH3, the ketone having its maximum absorption in the range of 350 to 550 nm.

The photopolymerizable compositions in addition to containing at least one ethylenically unsaturated com-pound, 2~4~5-triarylimidazolyl dimer, and an arylylidene aryl ketone preferably contain macromolecular organic binders. Other useful additives include: leuco dyes that are oxidizable to a dye by the triarylimidazolyl radicals, photoinhibitors, and inert components such as plasticizers, dyes and pigments to increase visibility of the image, fillers, etc.
The ethylenically unsaturated compound can be present in the photopolymerizable composition in an amount of 3.0 to 100 parts by weight, and the organic binder can be present in an amount of 0 to 97 parts by weight based on the weight of monomer and binder.
35 The 2,4,5-triarylimidazolyl dimer can be present in an amount of 0.01 to 20.0 parts by weight per 100 parts i~l3'~5 by weight of the combined weight of ethylenically unsaturated compound and binder. The arylylidene aryl ketone sensitizer can be present in an amount of 0.001 to 15.0 parts by weight, preferably 1.0 to 10.0 parts by weightl per 100 parts by weight of the combined weights of ethylenically unsaturated compound and binder. The other additives can be present in minor amounts known to those skilled in the art.
The ethylenically unsaturated compounds (1) ~photopolymerizable monomers of this invention) have a boiling point above 100C. at normal atmospheric pressure and are capable of forming a high polymer by photoinitiated, addition polymerization. Suitable compounds are disclosed in Chang U.S. Patent 3,756,827, column 2, line 36 to column 3, line 30. ~ther useful monomers include ethylenically unsaturated diester polyhydroxy polyethers as described in Chambers et al Belgian Patent 868,870. Examples include the Epocryl~
I resins sold by Shell Chemical Co. Many of the polymerizable monomers are subject to thermal polymer-ization, especially when stored for long periods or at elevated temperatures. When such compounds are supplied commercially, it is customary for them to contain a small, but effective, amount of a thermal polymerization inhibitor. These inhibitors may be left in the monomers when the photopolymerizable coating compositions of this invention are prepared, as was done in the examples which follow. The resulting compositions usually have satisfactory thermal stability. If unusual thermal exposure is anticipated, or if monomers containing little or no thermal polymerization inhibitor are employed, compositions with adequate shelf life can be obtained by incorporating, e.g., up to 0.5 percent, by ~.,, . "

~13139S

weight of monomer~ of a ther~al polymerization inhibi-tor such as hydroquinone9 methylhydroquinone, p-methoxy-phenol9 etcO
The 2,4~5 triarylimidazolyl dimers (2,2',4,4t, 595'-hexaarylbiimidazoles) are photodissociable to the corresponding triarylimidazolyl radicalsO These hexaarylbiimidazoles absorb maximally in the 255-275 nm regiong and usually show some, though lesser absorp-tion in the 300-375 nm region. Although the absorption bands ~end to tail out to include wavelengths as high as about 430 nm9 they normally require light rich in the 255-375 nm wavelengths for their dissociation~
m e hexaarylbiimidazoles can be represented by the formula B D B D

N ~ N N ~ N
A A
wherein Ag B and D represent aryl groups which can be the same or different, carbocyclic or heterocyclicg unsubstituted or substituted with substituents that do not inter~ere with the dissociation of the hexaaryl-biimidazole to the triarylimidazolyl radical or withthe oxidation of the leuco dye, and each dotted circle stands for four delocalized electrons (i.e., two con-jugated double bonds) which satisfy the valences of the carbon and nitrogen atoms of the ~midazolyl ring~
The B and D aryl groups can each be substituted with 0-3 substituents and the A aryl groups can be sub stituted with 0-4 substituents. Use~ul 2,4~5~triaryl-imidazol~l dimers are disclosed in Baum & Henry UOS.

113~3'~`~5 Patent 3J652~275 colun~ 5, line 44 to column 7, llne 16.
me arylylidene aryl ketone sensitizers use~ul in the photopolymerizable composition~ have been de~ined 5 broadly above. Pre~erred 3en~itizer co~poun~s are of ~he followlng structures:
A. 0 ~6 ~ ~ \ R

Rl is H, OH, CH30~;
R2 is H, OH~ CH30-;
R3 is HJ OHg CH30- W~ th the proviso that 1~
one of Rl, R2~ or R3 1~ OH then the remainder must be H
or CH30-;

i \ \ / 3 1, 2 or 3, -O-CH wherein R' is H, 0, or R~ \ I
Z i.~ linked with R4 where Z is / CH and R4 is -O- or -N-;

R4 i~ H~ CH3, OH, CH30- with the proviso that if one of Rl, R2, or R3 is OH then R4 is one o~ H, CH3 or CH30-;
R4 is E, CH3, OH, ~H30-;
CH _ 5 5 7 2 2 ~ H2 2 2 ' O CH2 2 ;

~13~395 6 6 R7 is -CH2CH2-, -CH2CH2CH -, 2 2 ;
R7 is CH3-, CH3CE2~;
B.
R2 Rl Rg

3~ C -C- C~ ~ R/R 10 R4 R~ R8 10 Rl is H, CH3;
R2 is H, OH, CH3, CH30;
R3 is H, CH3, OH, CH30;
R2 + R3 is -0-CH2-0-;

4 , 3 , H30 ;
R5 is H, CH3;
R6 is H, CH3;
R7 ls H, CH3, OH, CH30 with the proviso that if one of R2, R3 or R7 is OH then the remainder must be H, CH3 or CH30-;
R7 is H, CH3, OH, CH30;
8 ' 8 Rlo is -CH2cH2-~ -cH2cH2cH2 2 2 ;
R is H, Rg + Rlo is -CH2CH2, CH2C 2 2 --CH2cH2-;
Rlo is CH3-, CH3CH2 The sensitizers illustrated in the Examples are as follows:
30Example Name of Sensitizer 1 2-(4l-diethylamino-2 methylbenzylidene)-l-indanone 2 2-(4'-diethylaminobenzylidene)-3-hydroxy-1-indanone ~3~3~S

E xample Name of Sensitizer 3 8-(4'-dimethylaminobenzylidene)-acenaphthalene-7-one 4 2-(4'-diethylamino-2'-methylbenzylidene)-l-tetralone 4-diethylamino-2-methylbenzyli-deneacetophenone 6 4'_dimethylaminobenzylidene-4-dimethylaminoacetophenone 8 4'-diethylamino-2'-methyl-ben2ylidene-2-[B-(~'-methoxy-ethoxy)-ethoxy]acetophenone 9 4'-diethylamino-2'-methyl-benzylidene-2-methylacetophenone 4'-diethylamino-2'-methyl-benzylidene-4-fluoroacetophenone 11 4l-diethylamino-2l-methyl-benzylidene-4-cyanoacetophenone 12 2-(4'-diethylaminobenzylidene)-3-phenyl-1-chromanone 13 2-(4'-diethylaminobenzylidene)-l-chrcmanone ~313~;

Example Name of Sensitlzer 14 2-(4'-diethylaminobenzylidene)-chroman-1,3-dione 2-[4'-di-(~-chloroethyl)amino-benzylidene]-3-hydroxy-1-indanone 16 2-(4'-diethylamino-2'-methylbenzylidene)-3-hydroxy l-indanone 17 2-(4'-dimethylaminoclnnamyl-idene)-3-hydroxy-1-indanone 18 2-(4'-diethylamino-2'-methyl-benzylidene)-l-tetralone 19 2-(4'-diethylamino-2'-methyl-benzylidene)-l-benzosuberone 2-(4'-diethylamino-2'-methyl-benzylidene)-5,6-dimethoxy-l-indanone 21 4'-diethylamino-2'-methyl-benzylidene-3,4-methylene-dio~yacetophenone 22 4'-diethylamino-2'-methyl-benzylidene-4-methoxy-acetophenone 4'-diet~lylamino-2'-methyl-23 benzylidene-3-methoxy-acetophenone ~3 3~39S

Example Name of Sensitizer 24 4'-diethyl amino- 2'-methyl-benzylidene-4-methylaceto-ph2none 2-~4'-diethylamino-2'-methoxybenzylidene)-1-indanone 27 2-(9'-julolylidene)-1-indanone 28 2-(4l-diethylaminobenzylidene~-1-tetralone 29 2-(4l-diethylaminobenzylidene) propiophenone 2-(4'-diethylamino-2l-methyl-benzylidene)-propiophenone.
31 4-diethylaminobenzylidene-deoxybenzoin 39 2-(4'-diethylaminobenzylidene)-l-indanone 2-(4'-diethylaminobenzylidene)-3-gemdimethyl-1-indanone 47 4'-diethylamino-2'-methylbenzyli-dene-4-hydroxyacetophenone 48 4'-dimethylaminobenzylidene-3-hydroxyacetophenone The arvlylidene aryl ketones can be prepared according to procedures set ~orth in Examples 1 and 32 below according to known procedures reacting specific aryl ketones and p-dialkylaminoarylaldehydes. After purification, melting points, ultraviolet spectral data can be determined as shown below, e.g., in Table 3.
The sensitizers absorb radiation in the broad spectral range of 300 to 700 nm. The maximum absorption (~max.) is in the range of 350 to 550 nm, preferably 400 to 500 nm.
Preferably thermoplastic macromolecular organic polymeric binders are present in the photo-polymerizable compositions. Polymeric binder types include: (a) copolyesters based on terephthalic, isophthalic, sebacic, adipic and hexahydroterephthalic acids; (b) nylons or polyamides; (c) vinylidene chloride copolymers; (d) ethylene/vinyl acetate co-polymers; (e) cellulosic ethers; (f) polyethylene;
(g) synthetic rubbers; (h) cellulose esters; (i) polyvinyl esters including polyvinyl acetate/acrylate and polyvinyl acetate/methacrylate copolymers; (j) polyacrylate and poly-a -alkyl-acrylate esters, e.g., polymethyl methacrylate and polyethyl methacrylate;
(k) high molecular weight ethylene oxide polymers (polyethylene glycols) having average molecular weights from 4000-4,000,000; (1) polyvinyl chloride and copolymers; (m) polyvinyl acetal; (n) poly-formaldehydes; (o) polyurethanes; (p) polycarbon-ates; and (q) polystyrenes.

13~5 In a particularly preferred embodiment of thelnvention, the polymeric binder i8 gelected SO that the unexpQsed photopolymerlzable coating i~ soluble in pre-/ dominantly aqueous solutions, for example dllute aqueou~
alkallne solutions, but upon exposure to actinic radia-tion becomes relatlvely lnsoluble therein. Typically~
polymers which ~ati~fy these requirement~ are carboxy-lated polymers, for example vinyl addltion polymer6 contalning free carboxylic acid groups. Another pre-ferred group of binders ~neludes polyacrylate e~ter~and poly-~-alkyl-acrylate esters3 particularly poly-methyl methacrylate.
Optionally leuco dyes can al~o be present in the photopolymerizable composition~ By the term "Leuco dye" i~ meant the colorleæ~ (l.e., the reduced) form of a dye compound which can be oxldized to its colored form by the triarylimidazolyl radical. Leuco dye3 are disclosed in Baum & Henry U~S. Patent 3,652,2759 column 7, llne 24 to column 11~ line 32.
In preYerred positive ~orking photopoly-meriæable compositions, nitroaromatic photoinhibitors a3 di~clo~ed in Belgian Patent 852,517 granted September 16, 1977, are pre~ent. These compounds which can be present ~ amount~ of 0~5 to 15 part~ by weight per 100 part~ by weight of the combined welght of ethylenically unsaturated compound and binder are deflned by the formul~:

~,y .,~, .

~31395 ~(~ ~' M2 ~3 ~ \ CX~R5 wherein Rl, R2, R3 and R4, alike or different, are H, OH, halogen, NO2, CN, alkyl of 1 to 18 carbons, alkoxy in which the alkyl is of 1 to 18 carbons, aryl of 6 to 18 carbons, benzyl, halogen-substituted phenyl, polyether of 2 to 18 carbons and 1 to 6 oxygens, dialkylamino in which each alkyl is of 1 to 18 carbons, thioalkyl in which the alkyl is of 1 to 18 carbons, or thioaryl in which the aryl is of 6 to 18 carbons, or any two of Rl, R2, R3 and R4, taken together, are the residue of a second benzene ring fused onto the benzene nucleus, with the proviso that not more than one of Rl, R2, R3 and R4 is OH or NO2;
R5 is H, alkyl of 1 to 18 carbons, halogen, phenyl, or alkoxy in which the alkyl is of 1 to 18 carbons;
R6 is H, OH, alkyl of 1 to 18 carbons, phenyl, or alkoxy in which the alkyl is of 1 to 18 carbons, with the proviso that only one of RS and R6 is H, or;
R5 and R6 together are =O, =CH2, -O-CH2-, =NC6Hs, =NC6H4N(alkyl)2 in which each alkyl is of 1 to ~ 1~3i395 18 carbons, -O-C2H4-O-, =~(hydrocaroylene) ln which the hydrocarbylene group is of 1 to 18 carbons, or - C = C- NH - C 8 C -~ 7 R8 R9 R10 in which R and R ,alike or different, are H or alkyl of 1 to 4 carbons, and R and R , alike or different, are -CN, -CORll in which Rll is alkyl of 1 to 5 carbons, or -COOR12 in which R12 is alkyl of 1 to 6 carbons which may be interrupted by an oxygen atom, alkenyl of 2 to 5 carbons, or alkynyl of 2 to 5 carbons, or R7 and R8 together, or R9 and Rlo together, complete a 6-membered carbocyclic ring containing a keto group.
A wide range of non-polymerizable plasti-cizers are effective in achieving improved exposure and development temperature latitude. When a macromolecular binder is present in the layer, plasticizer selection would be based on those well known in the art to be compatible with it as well as the monomer, dimer, 113~395 _7 ketone anc' other components. ~l~h ac ylic binders, for example, dibutyl phthalate and other esters of aromatic acids; esters or aliphatic polyacids such as diisooctyl adipate, nitrate esters, etc.; aromatic or aliphatic acid esters of glycols, polyoxyalXylene glycols, ali-phatic polyols, etc.; alXyl and aryl phosphates; low molecular weight polyesters of poly-~-methylstyrenes;
chlorinated paraffins; and sulfonamide types may be ~ used. In general, water insoluble plasticizers are preferred for greater high humidity storage stability, but are not necessary to get improved latitude. Other inert additives such as dyes, pigments and fillers are known to t~ose skilled in the a~. These additives are generally present in minor amounts and should not interfere with the exposure of the photopolymerizable ayer.
The photopolym~rizable compositio~s ~escribecl herein may be coated on a wide variety of subtrates.
By "substrate" is meant any natural or synthetic sup-port, preferably one which is capable of existing in a flexible or rigid film or sheet form. For example, the substrate could be a metal sheet or foil, a sheet or film of synthetic organic resin, cellulose paper, fiberboard, and the like, or a composite of two or more of these materials. Specific substrates include alumina-blasted aluminum, anodized aluminum, alumina-blasted polyethylene terephthalate film, polyethylene terephthalate film, e.g., resin-subbed polyethylene terephthalate film, polyvinyl alcohol-coated paper, crosslinked polyester-coated paper, nylon, glass, cellulose acetate film, heavy paper such as litho-graphic paper, and the like.

~3~395 The particular substrate will generally be determlned by the use application lnvolved. For ex-ample, when printed circuits are produced, the substrate may be a plate which is a copper coating on fiberboard in the preparation of lithographic printing plates, the substrate is anodized aluminum.
Preferably the layer of the photopolymerizable compositions have a thickness ranging from about 0.0001 inch (~0.0003 cm) to about 0.01 inch (0.025 cm) and are adhered with low to moderate adherence to a thin, flexi-ble, polymeric film support which may transmit radiation actinic to the photopolymerizable layer. The opposite side of the photopolymerizable layer may have adhered thereto a protective cover layer or cover sheet wherein the sheet has less adherence to the layer than the ad-herence between the film support and the layer. A par-ticularly preferred support is a transparent polyethylene terephthalate film having a thickness of about 0.001 inch (~0.0025 cm). Polyethylene, 0.001 inch (~0.0025 cm) is a preferred cover sheet; polyvinyl alcohol coating is a preferred cover layer.
Any convenient source of actinic radiation providing wavelengths in the region of the spectrum 25 that overlap the arylylidene aryl ketone sensitizers absorption bands can be used to activate the photo-polymerizable compositions for triarylimidazolyl radi-cal formation, image formation and photopolymerization initiation. The li~ht can be natural or artificial, 30 monochromatic or polychromatic, incoherent or coherent, and for high efficiency should correspond closely in wavelengths to the sensitizer's principal absorption bands and should be sufficiently intense to activate a substantial proportion of the sensitizer.

~13~39S

Conventional light sources include fluorescent lamps, mercury, metal additive and arc lamps providing narrow or broad light bands centered near 405, 436 and 546nm (Hg) wavelengths. Coherent light sources are the

5 pulsed xenon, argon ion, and ionized neon-lasers whose emissions fall within or overlap the visible ab-sorption bands of the sensitizer. Ultraviolet and visible emitting ca~hode ray tu~es widely use~ul in printout systems for ~riting on photosensitive materials lO are also useful with the suhject compositions. These in general involve an ultraviolet or visible-emittin~
phosphor internal coating as the means for converting electrical energy to light energy and a ~iber optic face plate as the means for directing the radiation to 15 the photosensitive target.
Best Mode for Carrying out the Invention .
The best mode is illustrated in Example l wherein the sensitizer compound, 2-(4'-diethylamino-2'-methylbenzylidene)-l-indanone, is added to a photo-20 polymerizable formulation which is coated onto analuminum plate at a coating weight of 50 mg/dm2 A
polyvinyl alcohol containing layer is coated over the photopolymerizable layer, and the element formed is imagewise exposed in a vacuum frame to a mercury lamp 25 source. An ultraviolet filter, as described in Example l, is placed over the photopolymerizable layer which is then exposed. After development and rinsing with water as described in Example l, a lithographic printing plate is obtained.

~13133s Industrial ~pplicability The photopolymerizable compositions or this invention are useful in printing plates for offset and letter press, engineering drafting films, as well as photoresists in making printed circuits or in chem-ical milling, and as soldermasks. In printing plate ap-plications, an important use is in a positive/negative two exposure imaging system of a positive photopolymer litho printing plate. The compositions are also useful in positlve working photopolymer litho films. Still other uses are ~or preparing colored images from color separation negatives suitable for color-proofing. The - images formed with these elements may be used for making copies by thermal transfer to a substrate. Specific uses will be evident to those skilled in the art.
In photoresist applications, thin film resists prepared from the composition are useful in the prepara-tion of microcircuits. The resists can be either sol-vent soluble or aqueous developable. Solder masks are protective coatings whichare selectively applied to portions of a printed circuit board surface to confine solder to pad areas on the board and to prevent bridg-ing between conductors during tinning operations and during soldering of components. A solder mask also functions to prevent or minimize corrosion of the base copper conductors and as a dielectric to insulate certain components for adjacent circuitry.

Photopolymerizable compositions containing the arylylidene aryl ketone sensitizers of this invention surprisingly show improved visible light sensitization.
The remarkable increase in speed results in a saving of energy and costs related thereto since lower energy exposure sources can be used in exposure of the photo-polymerizable element or more elements can be exposed and developed in a given amount of time. Alternatively, the photopolymerizable layer can be exposed by means of an exposure source maintained at a greater distance than normal for known sensitized elements. This permits the exposing radiation to be collimated which is of particular advantage in forming halftone dots having substantially perpendicular sides. The broad sensi-tization range coupled with the effectiveness ofsensitization enables useful positive polymeric images to be formed by a double exposure process, first, image-wise in the ultraviolet region of the spectrum and the overall in the visible region of the spectrum utilizing specific nitroaromatic photoinhibitors.
Examples The invention will be illustrated by the following examples wherein the percentages are by weight.

Preparation of 2-(4'-diethylamino-2'-methyl-benzylidene)-l-indanone:

O CH

= CH ~ / 2 C 3 '~' .~ solution of 50 g. (.3785 mole) l-indanone and 77.75 g. of 93~ 4-diethylamino-2-methylbenzaldehyde in 150 ml. of ethanol was stirred and 94 ml. of a solution of warm (approx. 30C.) 25% aqueous sodium hydro~ide was added. This reaction mixture was heated to reflux for 45 minutes. A solid precipitate began appearing after 30 minutes. Next, the mixture was cooled to about 5C. and the precipitate filtered and washed with petroleum ether. After air drying, the resulting solid was washed with water until the wash material was pH 7Ø The washed precipitate was recry-stallized from 80~ aqueous ethanol to yield 96.6 g.
(80.1~ yield) of 2-(4'-diethylamino-2'-methylbenzyli-dene)-l-indanone (m.p. 133.5-134.5C), U.V. spectra and values are set forth in Table 3 below. The struc-ture was confirmed by both infrared and nuclear magnet-ic resonance spectra.
To test the efectiveness of this compound as a sensitlzer in a photopolymerizable element, the fol-lowing stock solution was prepared:
Component Amt. (g.) Resin binder(l) 149.61 Trimethylolpropane triacrylate 22.4 Plasticizer(2) 7.1 Bis(2-o-chlorophenyl-4,5-bis-phenyl) imidazole 6.5 Solvent Red Dye (C.I. #109) 1.0 Tri-(p-N,N-dimethylaminophenyl)-methane 0.2 Component Amt.(g.) 1,4,4-trimethyl-2,3-diazabicy~lo-t3~2O2] -non-2-ene N,N-dioxide 0.056 Ethyl "Cellosolve"* 336.7 (1) Low molec. wt. co-polymer of methyl methacrylate/
methacrylic acid in ethyl"Cellosolve" 42~75~ solids.
(2) Mixture of triethylene glycol dicaprate and tri-ethylene glycol dicaprylate (Sp. &r. - a ~ 966, Visc. = lS cps at 25C, Drew Chemical Corp., N.Y., NoYo) This material contained 18O57% as solids. A 50 g.
sample was taken and 0.0825 g. of the sensitiæer pre-pared above added thereto along with a 0.1718 g. sample of photoinhibitor (3,4-dimethoxy-6-nitrobenzaldehyde).
This final mixture was spin coated on a 0.012 inch (0O30 mm) aluminum plate~ The final coating weight of the photosensitive layer was 50 mg/dm20 The photosensi-tive layer was then overcoated with a 10 mg/dm layer comprising an aqueous solution of fully hydrolyzed poly-vinyl alcohol having a mixture of vinyl pyrrolidone/
vinyl acetate dispersed therein.
AftQr this plate was dried~ one half of the sur-25 ace was covered by a bla-k polyethylene sh~et. A suit-able tar~et was then placed over the unco~ered side and the plate was placed in a vacuum printins frame~ An imagewise exposure was then made (positive expo3ure) to a 2000 watt mercury lamp at a distance o~ 38 inches 30 ~96.5 cm) using an "Ascor"*Light Integrator Platemaker Model 1415-12 with a ~erkey "Ascor" 1601~40 light source.
The exposure was 20 units. The ~lack ~olyethylene sheet was then removed and a 3 ~ step wedge was placed over the previously blocked-off sectionO A U~VO fil~er~3) *denotes trade mark ~3 was placed o~7er the plate and the entire plate given a lO0 unit e~Yposure. This final exposure gave a negative exposure to the blocked-off section and com-pleted the 2 ex?osure positive sequence on the otherhalf. The exposed plate was then developed for 30 seconds at 22C in the following developer solution:
Amt. (%) Sodium carbonate~ ----- 1.86 Butyl carbitol----------------- 11.32 Water~ -~~~~~~~~~~~~~~~~~ 88.82 The developed plate was then rinsed under running water while the imaged areas were being gently swabbed with a cotton pad. A high ~uality relief image plate suit-able as a lithographic printing plate, was obtained.Both positive and negative images were on this plate.
In the positive mode, the first step was completely unpolymerized while in the negative mode, step 13 was the last polymerized step in the image~
___________________ , (3) The U.V. filter used in this example was prepared as follows:
PolYmer .~olution Amt. (g) Cellulose acetate butyrate720.0 Ethyl Cellosolve 320.0 Methylene chloride 2,880.0 (% solids is 18.36) This solution was stirred for about 90 minutes. A
sample of the U.V. absorber 2,2'-dihydroxy-4-methoxy-benzophenone was added so that the final solution contained 10% U.V. absorber and 90% polymer solution.
This material was coated on 0.004 inch (0.01 cm) resin-subbed polyethylene terephthalate film to a thickness of 0.00095 inch (0.024 mm) of U.V. absorber.

In a base catalyzed condensation reaction similar to that described in Example 1, the following sensitizers were prepared:

Sample Sensitizer O
~ C~ N/
H

3 ~ CH ~/=~N/

- 20 ¢~;CTi_~N~Et 2 5 C~I3 ¢~ C-CH=CH ~ N/

6 ~N (~3C-G~H--~3N~C~13 H3C~ \CH3 ~131395 Visible absorption data are set forth in TabLe 3 below.
These sensitizers were ~ested in the same photo-sensitive ~orr.ulation give~ Example 1 and coated, S overcoated, exposed and ~e~zQ~ oped as described therein with the follo~ins resul's:
Ta~le 1 ~ ~ SteP~re'~
S ~n~ Used L~t Or Photo -~CDo Un ~.s W 2e~cn~e ens ~ inh;b . Used (") ~F~ ltel t+ ) (- ) ~ o.og52 0.1711 2~ 10~~lJ 1 11 3 ~O 1~31 0~ ~737 30 20~~) 4 4 4 0~1529 o. 17la 4Q 200lA(2 ) 1 15 ~O 0475 oO ~ 711 20 lo~2c (~ ) 1 13 6 0~0952 0.173~ ~0 1002At2) ~1 8 These tests indicate that a.l are visible sensitizers and most ~crform ~e~l in the preparation of suitable positive/negative litho printing plates as described in Example lo 20 ~
(1) S~me W filter as Example lo (2) Rodak"Wratte~filters.

The following photopolymerizable composition 25 was prepaxedo Component Wt. Used (g~) -Copolymer of styrene/maleic anhydride 25907 (1O4/1)-Molo Wto caO 10~000 Dispersion ofoO
a) TerpolymeroOethyl acrylate (5606),) methyl methacrylate (37.6), acrylic acid (700), )pa~s) Acid No~ 76-o85~ MolO Wto ) ) 383~0 caO 260,000 35 b) Carbon Black )pa~s) * denotestrade mark ~31395 Tetrae~hylene glycol di.methacryla~e 70.1 Trimetholpropane triacrylate 70.1 Sensitiæer from Ex~ 1 4041 3~ 4-dimethoxy-6 nit.robenzyl 4 ' -methoxyphenyl ether 6000 Bis (2-o ~chlorophenyl~4 j S rbis-phenyl) imidazole 5206 "~C 430'* (fluoro surfactant from ~ Co.) 1D35 ~p4~4-trimethyl 2,3~diazabicyclo ~30202] non-2 ene N~N'-dioxide 0044 "Polyox'i*WSR N-3000, MoWo caO 40()/0()0~ 9oO
~Polyoxyethylene coating aid, ~nion Carbide CorpO) Methylene Chloride 3,21000 Methyl Chloxoform 1,53000 Methan~l 3500 This material was thoroughly mixed and then machine coated on the resin subbed side of a 0.004 inch (oOl cm) polyethylene terephthalate film support at lO0 ft/min (30048 m/min)0 The coating was dried a~ 200F (~3D30C) to yield a black, photopol~mer layer with a coating weight of about 50 ~g/dm20 ~ second, photopolymeriz-able composition containing the following ingxedients was prepared: .
Component Wt~ Used Water (distilled~ 46007 Terpolymer-as descri~e~ aho~e, 10%1,83800 aqueous solu~ion 30 . 'l~isco'~ AC-392 ~Polyethylene wax dispersed 35300 in water, Misco Products Co., Wheeling, Illinois) "Triton'~ X-lO0 (octylphenoxy polyethoxy909 ethanol~ dispersing agent, Rohm ~ Haas Co.) ~ethylene chloride 27500 Tetraethylene glycol d~methacrylate 56 D 4 Trimethylolpropane triacrylate ~ 56~4 ,Sensitizer ~rom Exo l . 3053 _ _ . . . .. . . . . .
* denotes trade mar~

1~3~3'35 Bi s ( 2~o-ch loropheny1-4, 5-bl s-phe n~yl ) ~ midaæole 42. 3 1,4,4-trimethyl-2,3-dlazabicyclo (3. 2- 2) non-2~ene-N, N ' -dloxide O. 36 This compo~ition was stirred thoroughly to admix all component~ and the mi~ture was coated contiguous to the ~irst photopolymer layer at 30 ft/min (914.4 cm/
min). me resultinæ layer (ca. 30 mg~dm~ was dried at 220 F (104.4 C~ and a 0.001 inch (.0025 cm) pol~-es~er cover sheet was lamlnated thereon.
Thi~ composite J multilayered element was expo~ed ror 20 second~ to a 4 IrW pulsed Xenon arc at a distance of 60 inche~ (152.4 cm) through a photographic posltive image ~n contact wlth the cover ~heet. The posltive image was then removed and the element re-expo~ed for 20 seconds to the same light ~ource through a cut-of~ ~ilter which ad~orb~ all the light below 400 nm. The cover sheet was then removed and the film pro-ce~sed through an autamatic processor described in U.S.
Patent 4 142 194J i~sued 1979 Februar~ 27, at 7 ft/m~n (353.36 cm/min) and 72F (22.2C) to produce an exact duplicate of the origlnal po~itlve image.

In a manner similar to that de~cribed ~n Example 1, the roll~wing ~en~ltizer~ were prepared:
Sample Sen~itizer , 8 (~ COCH=CH~ NEt2 C~
3 ~COCH-C~ t2 CH~
~F0COCH-CH~3~Et2 ,~,~

~L3139~i S2mD1~ Sensitize~

S 1 1 p--C~IT ;~iC OC H--C ~ t 2 Q
12 ~ (1) .. NEt2 13 ~ CH ~NEt2 1S 14 ~CH~

[~CH ~ N(CH2CH2Cl)2 16 ~CH ~ NEt2 H
17 ~>= CTA--CH-- CH~ NMe2 H

o CH3 18 (~CH~NEt2 19 3^~ ~NEt2 2 0 C113 O ~C~ ~E~2 3s 1~31395 S~nPleSensitiz~r .

21 ~[~ 2 22 ~-CH3 O¢CO~::H=C~Et2 23 m-CrI3O~ )CH=CH~ ~2 ~3 24 ~-CH3 ¢CC{~H=CH~)~Et2 25 ~ ~CC~H=C~YEt2 2 0 2 6 ~ = C H--~ NE t2 ~ ' 27 ~CH
O
28 ~ ~, C~ NEt2 290CQC- C~,~Et2 3 0 C H3 C~3 ,0c~ C=C~,Et2 31 ,~C OC=C7~E t2 ~31395 (1) These compounds were prepared by an acid catalyzed condensation reaction.
_______________ The visible absorption data are set forth in Table 3 below.
Sensitizers 8 to 31 were tested in the formu-lation set forth below us1ng the photoinhibitor of Example 1 in an amount of 2.72 percent by weight of solids.

Formulation A~t.(g) . . _ 10 Tetraethylene glycol dimethacrylate 15.0 Terpol~er described in Example 7 35.3 Copolymer of styrene/maleic anhydride described in Example 7 36.7 Bis(2-0-chlorophenyl-4,5-bis-phenyl) imidazole 8.6 Chloroform 527.0 Methanol 40,0 Each sample was coated on the resin subbed side of a 0.004 inch (0.01 cm) polyethylene terephthalate film sup-port using a 0.002 inch (0.005 cm) doctor knife and a 0.001 inch (0.0025 cm) polyethylene terephthalate cover sheet laminated over the layer at 180F (82C) and at 4 ft/min (121.9 cm/min). Each sample was exposed as described in Example 1 using the same UV filter described in that Example. The cover sheets were re-moved, and the image was developed at 22C, in a 90/10 aqueous solution of Na2CO3/NaHCO3 (3~ solids) for 5 seconds. The results of the exposure are set forth in Table 2.

Table 2 ~posure v3~ Step Wedge Sensi- U~its Respo~se Sample tizer (~? +
8 1.01 ~ ~5 6 5 9 0.76 10 30 6 7 0.77 10 40 3 6 i 11 0.79 5 200 4 : 12 0.95 10 30 5 7 13 0.76 5 40 5 7 14 0.80 - 200 - 3 0.93 60 20 1 7 16 0.80 5 100 3 6 17 0.75 10 200 1 7 18 0.76 10 30 4 . 6 19 0.82 10 30 5 5 2Q 0.90 10 30 4 9 21 0.83 10 30 5 - 6 22 0.80 10 30 5 6 23 0.80 10 30 6 5 24 0.76 10 40 4 6 0.73 10 30 6 5 26 0.8010 30 4 10 27 0.7810 30 5 9 28 0.7310 40 5 9 29 0.7310 100 6 7 0.7610 100 10 5 31 0.8810 180 6 7 i395 These tests indicate that these sensitizers are useful in the preparation of suitable positive/nega-tive images from a master, most performing in an ex~
cellent manner.

T~bl e _3 V~sible Absorption Dat~ o~ Se~sitii ~rs Exampla ~max(nm) E at ~max (nm) E at ~max (Ml) OD
C~cl3 ~axC~l~C`.; ~max Film of Example ~.-Jax 1 0 ~
-1 44332, ~00 43638,800 - _ 2 44242,900 3 44320,400 4 42717,600420 21,900 S 43023,200 6 41334,800 ~ 425 0.36 9 - - 408 25,900 415 0.38 iO _ _ 430 35,000 43S 0.41 15 1l 452 31,500 465 0.34 12 0.22 13 _ _ 426 33,700 435. 0.32 _ _ - - 415 0.40 16 _ - - - 453 0.38 17 - -- - - 470 0.41 18 42717,600420 21,900 425 0.15 19 - ~ 407 18,400 410 0.17 - - 427 38,100 445 0.42 20 21 ~ 427 34,100 435 0.37 22 423 30,400 432 0.36 23 _ - - '- 440 0.36 Z4 - ,- 426 32,900 435 0.39 25 43023,200 - - 438 0.40 26 r - 437 39,600 27 - - 447 37,400 28 _ _ 418 28,200 Z9 ~ - 383 22,000 --25 30 _ _ . _ 31 - - 350 26,300 -~13~395 E~AMPLE 32 The sensitizer of Example 1 was prepared as follows:
A solution of 1000 g. (7.57 mole) l-indanone and 1557 g. of 93% 4-diethylamino-2-methylbenzaldehyde was rapidly stirred into 3 liters of ethanol. The temperature of this solution was 12C. 1880 ml. of 25% solution of NaOH (625 g. NaOH and water up to 2500 g.) at 22C was added over a 10 min. period.
The reaction is exothermic and a temperature of 41 C
was reached. After 30 minutes, the temperature had fallen to 38C at which point the temperature was lowered to 5C in a toluene/dry ice bath. The re-sulting solid precipitate was recovered by filtra-tion and subsequently washed with 3 liters of 5C
ethanol. The filter cake was then resuspended in 3 liters of 5C ethanol and refiltered. This step was repeated at which point the solid was washed four times with 3 to 4 liters of cold water. Water washing was continued until the filtrate was a neutral pH.
The product was then dried thoroughly to yield 1977 g.
of the product which was 85.5~ of the theoretical yield. The final product structure was identified and the structure confirmed by melting point, U.V., I.R. and NMR spectra. The effectiveness of the re-sulting product was tested in the same manner as that described in Example 1 with equivalent results.

~i33L;~g~

E~AMPLE 33 The following photosensitive compositions were prepared:
Amount (g) Ingredient _ B C
Tetraethylene glycol dimethacrylate 1.79 1.79 1.79 Terpolymer as described ld in Example 7 3.56 3.56 3.56 Copolymer of styrene/
maleic anhydride (Ex. 7)3.78 4.58 3.70 Bis(2-o-chlorophenyl-4,5-bis-phenyl) imidazole0.87 __ 0.87 Sensitizer described in Example 1 -- 0.075 0.075 Methylene chloride 52.8752.8752.87 Methanol 4.014.01 4.01 These compositions (14.95% solids) were mixed thoroughly and then coated on polyethylene terephthalate film sup-ports as described in Examples 8-31 and the composite structures were given a positive exposure through a J~ stepwedge and the filter of Example 1 and were de-veloped as described in Examples 8-31. The following results were obtained:

3L131;~9~

F _ Exposure (units) Stepwed~e Response C 10 " 1~
This example demonstrates the unique advantage when the sensitizer of this invention is used in conjunction with an initiator (Film C)O The example additionally demonstrates that the sensitizer of this invention is not an initiator by itself (Control Film B) and that when the sensitizer of ~his invention is omitted (Control Film A) a relatively low speed photosensitive composition is obtainedO
Example 34 The following photopolymerizable composi-tion was preparedo Ingredient Amount (g) Tetraethyleneglycol dimethacrylate 0O75 Terpolymer as described in Example 7 1O765 Copolymer of styxene/maleic anhydride as described in Example 7 1~614 Bis(2-o chlorophenyl-4,5 bis-p-t~
butyl-phenyl)imidazole 0O652 Sensitizer described in Example 10O037 6-Nitroveratraldehyde 0O135 25 Methylene chloride 26O34 Methanol 2O0 1131~9~

This composition was mixed thoroughly and coated on polyethylene terephthalate ~ilm supports as described in Examples 8~31. A polyethylene tere-phthalate coversheet was laminated thereon as describedin Examples 8-31, and the composite structure was given a positive exposure through a 3~2 stepwedge and an overall exposure with the filter of Example 1 and developed as described in Examples 8-310 The fol~
lowing results were obtainedO
Table 5 .. ..
Positi~e Overall Positive Negative Imagewise Polymerization Stepwed~e Stepwedge Exposure Exposure Image Image 5 units 30 units 4 6 .
The sensitizers in these examples were tested in the same photopolymerizable for~ulation disclosed in Example 1 except that no photoinhibitor - was present~ The solutions were coated and over-coated as described in Example 1. Only a visible polymerization exposure was given with the same source as described in Example 1. The plates were developed also as described in Example 1.

Table 6 Amount Exoo- 3~ Step-Sensi- Used sure UV we~ye _Example tizer ~) Units Pi}ter Ima~e 35 1 0.92 100 F lter ~0 B . 1 36 4 1~62 .

~3~395 These samples illustrate the utility of these visible sensitizers in high speed ~egative working litho-graphic printing plates.

The sensitizers in these examples were tested in the sam~ photosensitive formula~ion given in Examples 8-31 except that no pho~oinhibitor was present.
The solutions wer~ coated and laminated as described in Examples 8-310 O~ly a visihle polyn~erization exposure was given with the same sour~e as in Examples 8 310 The film~ were developed ~lso a~ ~escribed in Examples 8~310 ~ab Ame.
Used Exposure U.~. ~ tepwedge ExSensitizer % Uni~s Fi~ter Image 37 1 n. 75 10 Ex. 1 filter 10 38 1. 5~ 10 " 1~

20 39~ CH ~ ~Et2 2.0 10 ~ 12 40~ CX ~ ~Et2 2.0 10 " 8 25 4~ 5 1.3 10 ~ ~
42 1~ 0.84 30 'Y 13 43 26 0O70 200 Kodak~Wratten~ 8 9 44 27 0O$ 10 " 7 27 3.0 10 '~ 152 These examples illustrate. ~he utili~y of thcse visible sensi~
tizers in high speed films.

Prepared in a manner similar to tha~ described i~ Example 1.
2 Developed for six seconds at 22~C.

~139S

A ilm was made by coating the foliowing solution ~ha~ was 11O5% solids in me~hylene chloride on a 0~001 inch (0.025 mm) polyethylene terephthalate support at 40 mg/dm2 and by lamina~ing to Du Pont double matted~OO005 inch (10.127 mm) thick-drafting filmO
Component Total Solids (%) 10 Poly(methyl methacrylate) 11.51 wt av MW 40~000 Poly(methyl methacrylate)12.11 wt av MW 2500000 Poly(n-butyl/isobutyl methacrylate) 6.06 wt av MW 120,000 Poly~inyl formal 0.60 wt av MW 14,000 to 17,000 Polyoxyethylated tximethylol propane 27.38 triacrylate - 20 Bis(2-o-chlorophenyl-4~5-bis-m-methoxy-3.00 phenyl)imidazole 2 (4'~diethylamino-2l-methylbenzylidene)- 0.75 l-indanone Tri(2 methyl-4-~,N-diethylaminophenyl)-0.30 methane Tri~ N,N-dimethylaminophenyl)-methane0.30 Carbon black dispersion 38.00 Carbon black (29~00% o~ solids) AB type dispersant (9.00% of solids) The A segment i5 a triisocyanate ("Desmodur"*N and the B segment i5 a (58/42) copolymer of methacrylic acid/2 ethylhexylacrylate of 9,000 MW.

3 ~ * denote~ trade mark 1~31395 The film was exposed with a GE high intensity visible fluorescent bulb ~F54T17SPD (~max 425 nm) with the film passing by the bulb on a conveyor at 5 ft/min (1.52 m/min) or an exposure time of 2.2 sec. The cover sheet was peeled away to leave a positive image on the drafting film support, the polymerized imaged areas adhering to the cover sheet. This example demonstrates the utility of the sensitizer of Example 2 in an engin-eering drafting film.

A photopolymerizable solution was prepared by mixing the following components:
Component Amount (g.) 15 2-ethoxyethanol 46.7 Low MW copolymer of methyl methacry-late/methacrylic acid, 40% solids in 2-ethoxyethanol 11.3 Mixture of triethylene glycol dicaprate and triethylene glycol dicaprylate described in Example 1 0.9 Triethylene glycol dimethacrylate 2.38 Methacrylated polymeric epoxy resin of ~ Bisphenol-A and epichlorohydrin, MW
about 513 8.4 Bis(2-o-chlorophenyl-4,5-bis-m-methoxy-phenyl)imidazole 0.55 Bis(2-o-chlorophenyl-4,5-bis-phenyl) imidazole 0.28 Tri(2-methyl-4-N,N-diethylaminophenyl)-methane 0.23 Sensitizer of Ex. 30 0.45 13~S
41The solution was coated and overcoated as in Example lo Only a visible polymerization exposure was given with the same source as was used in Example 1, and the plate was developed as was Example 1 but with a 60 sec soak in the developer.
Exposure 2 Stepwedge Units Filter Image Kodak 10 ~Wxatten~
#8 This example demonstrates a negatlve working high speed lithographic plate that can be imaged with A >480 nmc The following sensitizers were prepared similar to the procedure described in Example 1:
Sample Sens t z~r 47 p-HU-0~COCH=CH- ~ NEt2 48 m-HO-0-COCH=C~ Me2 These sensitizers were tested in the formulation de-scribed in Examples 8-31~ coatedf laminated, exposed and developed as described therein except for the time of image development which is shown in the results listed below.
Dev~l.Time ~ Stepwedge Sensitizer Ex~osure Uni.s ~t 22 R'esponse Sample ~) + - _Se~

47 0.76 10 30 6 7 6 ~8 0.63 ~0 30 7 2 g This test showed that these compounds were extremely use-ful in the preparation of suitable positive/negative images from a master.

113~3'~5;
~2 Five black, photopolymerizable composi~
tions (for lower layer~ were prepared as desGribed in Example 7 varylng only in the monomeric com-5 pound as followsO
Sample (g) Monomeric Component 43 50 51 52 53 Tetraethylene glycol dimethacrylate 70 ol 140~ 2 ~ ~ ~
10 Trimethylolpropane triacrylate70O1 - 140.2 -1,6-hexanediol dimethacrylate - - ~ 190~2 Pentaerythritol triacrylate - - - 140.2 The photopolymerizable compositions were coated on a polyethylene terephthalate film and dried as des-cribed in Example 7.
A second set of five clear photopolymeri zable compositions were then prepared as described in Example 7 from the followin~ components, with the monomeric component varying as indicated below.
om~o ent Amount (g?
(a) Methylene Chloride 4640.0 25 (b~ ~ethanol . 230.0 (c) Ethyl Cellosolve 155.0 (d) 6-nitroveratraldehyde 22.5 (e) Sensitizer of Ex. l 7.2 (f) Bis (2-o-chlorophenyl 4,5 bis-phenyl)imidazole77.4 (g) "FC-430" (fluoro surfactant from 3M CoO) (10~ aqueous solution) 10.0 ml :~13~39S
~3 Component (cont'd)Amount (g) tcont'd) (h) 1~4,4-trimethyl-2,3~
diazabicyclo [3 2O2i non~2 ene N,N'-dioxide 0.45 ~i) Copolymer of styrene/maleic anhydride (1O4/loO)~
MoWto ca 10,000 328~0 (j) Terpol~mer ethyl acrylate (56 D 6); methyl methacry~
late (37.6)~ acrylic acid (7On) Acid Noc 76-85, M~to ca 260,000 328.0 (k) "Polyox" WSR~N-3000, ~oWt~ ~a 40a~0~0 (polyoxyethylene coating aid~ Uni.on Carbide Corp.) (9O0 g suspended in 75 ~
o ethyl~'CellosQlvel'81.0 ml Sam~le (~) Monomeric Component _ 50 51 52 53_ _ Tetraethylene glycol dimethacrylate 67.5 L35.0 - -Trimethylolpropane triacrylate67~S - 135.0 25 1,6~rhexanediol~
dimethacrylate - - 135.0 Pentaerythritol triacrylate - ~ o 135O0 The clear photopolymerizable con~ositions were coated contiguous to the first photopolymer layer and dried as described in Example 7O
Each multilayered element was exposed and processed as described i~ Example 7 to produce an exact duplicate of the original positive image~

Claims (17)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A photopolymerizable composition comprising an admixture of (1) at least one non gaseous ethylenically unsaturated compound having a boiling point above 100°C, at normal atmospheric pressure and being capable of forming a high molecular weight polymer by photoinitiated, addition polymerization;
(2) at least one 2,4,5-triarylimidazolyl dimer consisting of two lophine radicals bound together by a single covalent bond; and (3) a sensitizing amount of an arylylidene aryl ketone compound of the formulae:

A.

wherein A, B, D, E are carbon atoms or one may be solely a nitrogen atom:
R1 is H, OH or CH3O;
R2 is H, OH, CH3O or N(R7)2;
R3 is H, OH or CH3O;
a is 0 or 1;
b is 1, 2 or 3, , , , wherein R' is H, phenyl, or Z is linked with R4 where Z is and R4 is -O- or a being O;

R4 is H, CH3, OH, CH3O;
R5 is H or R5 + R7 is CH2CH2-, -CH2CH2CH2-, -O-CH2CH2;
R6 is H or R6 + R7 is -CH2CH2-, -CH2CH2CH2-, -O-CH2CH2-; and R7 is CH3, -(CH2)n-CH3 where n is 1 to 5, -CH2CH2-Cl, -CH2CH2OH, CH2CH2OCH3;
B.
wherein A, B, D are carbon atoms or one may be solely a nitrogen atom;
R1 is H, CH3, -OCH2CH2OR, wherein R is H, CH3, -CH2CH2OR' wherein R' is CH3 or CH3CH2-;
R2 is H, CH3, OH or CH30;
R3 is H, OH, CH3O, CH3, F, Br, CN or N(R10)2;
R2 + R3 is -O-CH -O-;
R4 is H, CH3 or CH3O;
R5 is H, CH3, -OCH2CH2OR, wherein R is H, CH3, -CH2CH2OR' wherein R' is CH3 or CH3CH2-;
R6 is H, CH3 or phenyl;
R7 is H, CH3, OH or CH3O;
R8 is H;
R8 + R10 is -CH2CH2-, -CH2CH2CH2-, -OCH2CH2;

R9 is H, R9 + R10 is -CH2CH2-, -CH2CH2CH2-, -OCH2CH2-; and R10 is CH3, ?CH2?nCH3 wherein n is 1 to 5; and C.
wherein G is , -O-, or -S-;
R1 is H, CH3 or -OCH3, and R2 is CH3 or -CH2CH3, the ketone having its maximum absorption in the range of 350 to 550 nm.

2. A photopolymerizable composition according to Claim 1 wherein the arylylidene aryl ketone com-pounds are of the formulae:
A.
R1 is H, OH, CH3O-;
R2 is H, OH, CH3O-;
R3 is H, OH, CH3O with the proviso that if one of R1, R2 or R3 is OH then the remainder must be H or CH3O-;

Z is , ?H2?a wherein a is 1, 2 or 3, wherein R' is H, ?, or Z is linked with R4 where Z is 2nd R4 is -O- or ;
R4 is H, CH3, OH, CH3O- with the proviso that if one of R1, R2 or R3 is OH when R4 is one of H, CH3 or CH3O-;
R5 is H or R5 + R7 is -CH2CH2-, CH2CH2CH2-, -O-CH2CH2-;
R6 is H or R6 + R7 is -CH2CH2H-, -CH2CH2CH2-, -O-CH2CH2-;
R7 is CH3-, CH3CH2-;
B.

R1 is H, CH3;
R2 is H, OH, CH3, CH3O;
R3 is H, CH3, OH, CH3O;
R2 + R3 is -O-CH2-O-;
R4 is H, CH3-, CH3O-;
R5 is H, CH3;
R6 is H, CH3;
R7 is H, CH3, OH, CH3O with the proviso that if one of R2, R3 or R7 is OH then the remainder must be H, CH3 or CH3O-;

R8 is H, R8 + R10 is -CH2CH2-, -CH2CH2CH2-, -O-CH2CH2-;
R9 is H, R9 + R10 is -CH2CH2, -CH2CH2CH2-, -O-2CH2-;
R10 is CH3-, CH3CH2-.

3. A photopolymerizable composition according to Claim 1 additionally containing (4) at least one macromolecular organic polymeric binder, the ethylenic-ally unsaturated compound and the binder being present in relative amounts of 3.0 to 100 and 0 to 97 parts by weight, respectively.

4. A photopolymerizable composition according to Claim 3 wherein the 2,4,5-triarylimidazolyl dimer is present in an amount of 0.01 to 20.0 parts by weight per 100 parts by weight of the combined weight of ethylenically unsaturated compound and binder.

5. A photopolymerizable composition according to Claim 4 wherein the arylylidene aryl ketone compound is present in an amount of 0.001 to 15.0 parts by weight per 100 parts by weight of the combined weight of ethyl-enically unsaturated compound and binder.

6. A photopolymerizable composition according to Claim 1 wherein the arylylidene aryl ketone is 2-(4'-diethylamino-2'-methylbenzylidene)-1-indanone.

7. A photopolymerizable composition according to Claim 1 wherein the arylylidene aryl ketone is 2-(4'-diethylamino-2'-methoxybenzylidene)-1-indanone.

8. A photopolymerizable composition according to Claim 1 wherein the arylylidene aryl ketone is 2-(9'-julolylidene)-1-indanone.

9. A photopolymerizable composition according to Claim 1 additionally containing 0.5 to 15.0 parts by weight per 100 parts by weight of the combined weight of ethylenically unsaturated compound and binder of a nitroaromatic compound of the formula:

wherein R1, R2, R3 and R4, alike or different, are H< OH, halogen, NO2, CN, alkyl of 1 to 18 carbons, alkoxy in which the alkyl is of 1 to 18 carbons, aryl of 6 to 18 carbons, benzyl, halogen-substituted phenyl, polyether of 2 to 18 carbons and 1 to 6 oxygens, dialkylamino in which each alkyl is of 1 to 18 carbons, thioalkyl in which the alkyl is of 1 to 18 carbons, or thioaryl in which the aryl is of 6 to 18 carbons, or any two of R1, R2, R3 and R4, taken together, are the residue of a second benzene ring fused onto the benzene nucleus, with the proviso that not more than one of R1, R2, R3 and R4 is OH or NO2;
R5 is H, alkyl of 1 to 18 carbons, halogen, phenyl, or alkoxy in which the alkyl is of 1 to 18 carbons;
R6 is H, OH, alkyl of 1 to 18 carbons, phenyl, or alkoxy in which the alkyl is of 1 to 18 carbons, with the proviso that only one of R5 and R6 is H, or;
R5 and R6 together are =O, =CH2, -O-CH2-, -NC6H5, =NC6H4N(alkyl)2 in which each alkyl is of 1 to 18 carbons, -O-C2H4-O-, in which the hydrocarbylene group is of 1 to 18 carbons, or in which R8 and R9, alike or different, are H or alkyl of 1 to 4 carbons, and R7 and R10, alike or different, are -CN, -COR11 in which R11 is alkyl of 1 to 5 carbons, or -COOR12 in which R12 is alkyl of 1 to 6 carbons which may be interrupted by an oxygen atom, alkenyl or 2 to 5 carbons, or alkynyl of 2 to 5 carbons, or R7 and R8 together, or R9 and R10 together, complete a 6-membered carbocyclic ring containing a keto group.

10. A photopolymerizable composition accord-ing to Claim 1 wherein the ethylenically unsaturated compound is trimethylolpropane triacrylate.

11. A photopolymerizable composition accord-ing to Claim 1 wherein the ethylenically unsaturated compound is tetraethylene glycol dLmethacrylate.

12. A photopolymerizable composition according to Claim 1 wherein the ethylenically unsaturated compound is a methacrylated polymeric epoxy resin of Bisphenol-A
and epichlorohydrin.

13. A photopolymerizable composition according to Claim 3 wherein the polymeric binder is a methyl meth-acrylate/methacrylic acid copolymer.

14. A photopolymerizable composition according to Claim 3 wherein two polymeric binders are present, one being a copolymer of styrene/maleic anhydride and the second a terpolymer of ethyl acrylate/methyl meth-acrylate/acrylic acid.

15. A photopolymerizable composition according to Claim 3 wherein the ethylenically unsaturated com-pound is trimethylolpropane triacrylate, the polymer binder is a copolymer of methyl methacrylate/methacrylic acid, the 2,4,5-triarylimidozolyl dimer is bis(2-o-chloro-phenyl-4,5-bis-phenyl)imidazole and the arylylidene aryl ketone is 2-(4'-diethylamino-2'-methylbenzylidene)-1-inda-none.

16. A photopolymerizable element comprising a support coated with a composition according to Claim 1.

17. A photopolymerizable element according to Claim 16 wherein the support is a polymeric film or metallic surface.