Photopolymerizable composition containing a novel combination of photopolymerizable initiators

A photopolymerizable composition comprising (A) an addition-polymerizable unsaturated compound having two or more ethylenically unsaturated double bonds and (B) a ternary photopolymerization initiator system, comprising a combination of a 4,4'-bis(dialkylamino)benzophenone represented by the following general formula (I), a carbonyl compound represented by the following general formula (IIa) or (IIb), and a compound having a group represented by the following general formula (III): ##STR1## wherein each R, which may be the same or different, represents an alkyl group, a cycloalkyl group or a hydroxyalkyl group, or may be bonded to another R substituent of the same nitrogen atom to form a tetramethylene group, a pentamethylene group or an oxybisethylene group; ##STR2## wherein X represents a single bond, an oxygen atom, a sulfur atom, a substituted or unsubstituted nitrogen atom or a carbonyl group, R.sup.1 and R.sup.2, which may be the same or different, each represents an alkyl group, an alkoxy group, a carboxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a halogen atom, and m and n each represents an integer of 0 to 3; ##STR3## wherein R.sup.3 and R.sup.4, which may be the same or different, each represents an alkyl group, an alkoxy group, a carboxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, a cyano group or a halogen atom, p represents an integer of 0 to 5, and q represents an integer of 0 to 4; and EQU --CY.sub.3 (III) wherein Y represents a halogen atom.

FIELD OF THE INVENTION 
This invention relates to a photopolymerizable composition containing a 
novel combination of photopolymerization initiators. More particularly, it 
relates to a photopolymerizable composition having high sensitivity and 
providing a photo-hardenable film of excellent film strength, suitable for 
preparing lithographic printing plates, resinous letterpresses, and 
resists or photomasks for printed-wiring boards. 
BACKGROUND OF THE INVENTION 
A photopolymerizable composition fundamentally comprises a 
photopolymerization initiator and a polyfunctional monomer, that is 
hardened upon being irradiated with light to become insoluble in solvents. 
Such compositions are widely utilized in photography, printing, surface 
processing of metals, inks, etc. (see J. Kosar, Light-Sensitive Systems, 
158-193 (J. Wiley & Sons, New York, 1965)). 
Studies on photopolymerizable compositions have been made to enhance their 
sensitivity to light, and many photopolymerization initiators have been 
proposed to achieve the end; for example, benzoin ethers described in U.S. 
Pat. No. 2,448,828, benzoins described in U.S. Pat. No. 2,722,512, 
anthraquinones described in U.S. Pat. No. 3,046,127, aminophenylketones 
and active methyl or amino compounds described in Japanese Patent 
Publication No. 11936/74 (corresponding to U.S. Pat. No. 3,661,588), 
Michler's ketone and benzophenone described in U.S. Pat. No. 3,682,641, 
and benzophenone and 4-N,N-dimethylaminobenzophenone described in Japanese 
Patent Publication No. 38403/73 (U.S. Pat. No. 3,549,367). These 
photopolymerization initiators improve photosensitivity to some extent, 
but the resulting photo-hardened products (particularly film-like hardened 
products) have mechanical properties that may be insufficient for various 
end uses. 
For example, when used as dry film resist in preparation of printed-wiring 
boards, they provide insufficient film strength after photo-hardening. 
Japanese Patent Publication No. 25231/70 describes dry film resists for 
preparing printed-wiring boards, and more detailed descriptions are given 
in, for example, W. S. De Forest, Photoresist, 163-212 (McGraw-Hill, New 
York, 1975). The main use of dry film resists is for preparation of 
perforations by tenting. However, conventionally known photopolymerization 
initiators have the disadvantage that due to insufficient strength of the 
tenting film, film breakage occurs in developing and etching steps. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a photopolymerizable 
composition which forms a photo-hardened film having excellent strength. 
Another object of the present invention is to provide a photopolymerizable 
composition having high photo-sensitivity. 
Other objects of the present invention will become apparent from the 
following description of the present invention. 
These and other objects of the invention have now been attained by a 
photopolymerizable composition containing a novel combination of 
photopolymerization initiators, and specifically, a photopolymerizable 
composition comprising (A) an addition-polymerizable unsaturated compound 
(polyfunctional monomer) having two or more ethylenically unsaturated 
double bonds within its molecule and (B) a ternary photopolymerization 
initiator system, which contains as the initiator a combination of a 
4,4'-bis(dialkylamino)benzophenone represented by the following general 
formula (I), a carbonyl compound represented by the following general 
formula (IIa) or (IIb), and a compound having a group represented by the 
following general formula (III): 
##STR4## 
wherein each R, which may be the same or different, represents an alkyl 
group (preferably having 1 to 6 carbon atoms), a cycloalkyl group 
(preferably having 5 or 6 carbon atoms) or a hydroxyalkyl grop (preferably 
having 2 to 6 carbon atoms), or may be bonded to another R substituent of 
the same nitrogen atom to form a tetramethylene group, a pentamethylene 
group or an oxybisethylene group; 
##STR5## 
wherein X represents a single bond, an oxygen atom, a sulfur atom, a 
substituted or unsubstituted nitrogen atom (a preferred substituent is a 
methyl group) or a carbonyl group, R.sup.1 and R.sup.2, which may be the 
same or different, each represents an alkyo group (preferably having 1 to 
3 carbon atoms), an alkoxy group (preferably having 1 to 3 carbon atoms), 
a carboxy group, an alkoxycarbonyl group (preferably having 2 to 21 carbon 
atoms), an aryloxycarbonyl group (preferably having 7 to 21 carbon atoms), 
or a halogen atom (e.g., a chlorine or bromine atom), and m and n each 
represents an integer of 0 to 3; 
##STR6## 
wherein R.sup.3 and R.sup.4, which may be the same or different, each 
represents an alkyl group (preferably having 1 to 3 carbon atoms), an 
alkoxy group (preferably having 1 to 3 carbon atoms), a carboxy group, an 
alkoxycarbonyl group (preferably having 2 to 21 carbon atoms), an 
aryloxycarbonyl group (preferably having 7 to 21 carbon atoms), a cyano 
group or a halogen atom (e.g., a chlorine or bromine atom), p represents 
an integer of 0 to 5, and q represents an integer of 0 to 4; and 
EQU --CY.sub.3 (III) 
wherein Y represents a halogen atom (e.g., a chlorine or bromine atom). 
DETAILED DESCRIPTION OF THE INVENTION 
Specific preferred examples of the compounds of general formula (I) used in 
the present invention include 4,4'-bis(dimethylamino)benzophenone, 
4,4'-bis(dicyclohexylamino)benzophenone, 
4,4'-bis(diethylamino)benzophenone, 
4,4'-bis(dihydroxyethylamino)benzophenone, 
4,4'-bis(morpholino)benzophenone, etc. Particularly preferred compounds 
include 4,4'-bis(dimethylamino)benzophenone and 
4,4'-bis(diethylamino)benzophenone. 
Specific examples of the compounds of general formula (IIa) include 
fluorenone, xanthone, thioxanthone, 2-chlorothioxanthone, 
2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, N-methylacridone, 
2-t-butylanthraquinone, 2-methylanthraquinone, 2-chloroanthraquinone, 
etc., with xanthone, fluorenone, and 2,4-diethylthioxanthone being 
particularly preferred. 
Specific examples of the compounds of general formula (IIb) include 
2-benzoylpyridine, 3-benzoylpyridine, and 4-benzoylpyridine, with 
4-benzoylpyridine being particularly preferred. 
As the compounds having a group of general formula (III), those selected 
from among compounds represented by the following general formulae (IIIa) 
to (IIIe) are preferred: 
##STR7## 
wherein Ar.sup.1 represents a substituted or unsubstituted phenyl or 
naphthyl group, and Z represents a chlorine or bromine atom; 
##STR8## 
wherein Ar.sup.2 represents a substituted or unsubstituted phenyl or 
naphthyl group, W represents a hydrogen atom, an alkyl group (preferably 
having 1 to 6 carbon atoms) or an aryl group (preferably having 6 to 20 
carbon atoms), and Z represents a chlorine atom or a bromine atom; 
EQU Ar.sup.3 --SO.sub.2 CZ.sub.3 (IIIc) 
wherein Ar.sup.3 represents a substituted or unsubstituted phenyl or 
naphthyl group, and Z represents a chlorine atom or a bromine atom; 
##STR9## 
wherein Z represents a chlorine atom or a bromine atom; and 
##STR10## 
wherein R.sup.2 represents CZ.sub.3, or a substituted or unsubstituted 
phenyl or naphthyl group; R.sup.3 represents CZ.sub.3, NH.sub.2, 
NHR.sup.4, N(R.sup.4).sub.2, SR.sup.4, OR.sup.4 or R.sup.4 ; R.sup.4 
represents an alkyl group (preferably having 1 to 6 carbon atoms), an aryl 
group (preferably having 6 to 20 carbon atoms), or an alkenyl group 
(preferably having 2 to 6 carbon atoms); and Z represents a chlorine atom 
or a bromine atom. 
Examples of substituents on the phenyl group or the naphthyl group 
represented by Ar.sup.1 in general formula (IIIa) include a halogen atom, 
an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 
carbon atoms, a nitro group, a cyano group and a methylenedioxy group. 
Examples of substituents on the phenyl group or the naphthyl group 
represented by Ar.sup.2 in general formula (IIIb) include a halogen atom, 
an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 
carbon atoms, a phenoxy group, an acetoxy group, a nitro group, a cyano 
group and a phenyl group. 
Examples of substituents on the phenyl group or the naphthyl group 
represented by Ar.sup.3 in general formula (IIIc) include a halogen atom, 
an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 
carbon atoms and a nitro group. 
Examples of substituents on the phenyl group or the naphthyl group 
represented by R.sup.2 in general formula (IIIe) include a halogen atom, 
an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 
6 carbon atoms. 
The compounds of general formula (IIIa) are described in Japanese Patent 
Application (OPI) No. 77742/80 (U.S. Pat. No. 4,279,982) (the term "OPI" 
as used herein refers to a "published unexamined Japanese patent 
application"), and preferred examples thereof include 
2-trichloromethyl-5-phenyl-1,3,4-oxadiazole, 
2-trichloromethyl-5-(4-chlorophenyl)-1,3,4-oxadiazole, 
2-trichloromethyl-5-(1-naphthyl)-1,3,4-oxadiazole, 
2-trichloromethyl-5-(2-naphthyl)-1,3,4-oxadiazole, 
2-tribromomethyl-5-phenyl-1,3,4-oxadiazole, 
2-tribromomethyl-5-(2-naphthyl)-1,3,4-oxadiazole, etc., with 
2-trichloromethyl-5-(1-naphthyl)-1,3,4-oxadiazole and 
2-trichloromethyl-5-(4-chlorophenyl)-1,3,4-oxadiazole being particularly 
preferred. 
The compounds represented by general formula (IIIb) are described in 
Japanese Patent Application (OPI) No. 74728/79 (U.S. Pat. No. 4,232,106), 
and preferred examples thereof include 
2-trichloromethyl-5-styryl-1,3,4-oxadiazole, 
2-trichloromethyl-5-(4-chlorostyryl)-1,3,4-oxadiazole, 
2-trichloromethyl-5-(4-methoxystyryl)-1,3,4-oxadiazole, 
2-trichloromethyl-5-(1-naphthyl)-1,3,4-oxadiazole, 
2-trichloromethyl-5-(4-n-butoxystyryl)-1,3,4-oxadiazole, 
2-tribromomethyl-5-styryl-1,3,4-oxadiazole, etc., with 
2-trichloromethyl-5-(4-chlorostyryl)-1,3,4-oxadiazole and 
2-trichloromethyl-5-(4-n-butoxystyryl)-1,3,4-oxadiazole being particularly 
preferred. 
Examples of the compounds represented by general formula (IIIc) include 
phenyltribromomethylsulfone, p-nitrophenyltribromomethylsulfone, 
p-chlorophenyltribromomethylsulfone, etc., with 
phenyltribromomethylsulfone being particularly preferred. 
Examples of the compounds of general formula (IIId) include 
2-trichloromethylquinazoline and 2-tribromomethylquinazoline, with 
2-trichloromethylquinazoline being particularly preferred. 
The compounds represented by general formula (IIIe) are described in 
Japanese Patent Application (OPI) No. 74887/79 (U.S. Pat. No. 4,239,850), 
and examples thereof include 2,4,6-tris(trichloromethyl)-s-triazine, 
2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 
2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 
2-(4-chlorophenyl)-4,6-bis(tribromomethyl)-s-triazine, etc., with 
2,4,6-tris(trichloromethyl)-s-triazine and 
2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine being particularly 
preferred. 
Preferred examples of the ternary photopolymerization initiator system of 
the present invention are as follows: 
__________________________________________________________________________ 
Compound Represented by 
Compound Represented by 
Compound Represented 
Formula (I) Formula (IIa) or (IIb) 
by Formula (III) 
__________________________________________________________________________ 
4,4'-bis(diethylamino)- 
4-benzoylpyridine 
2-trichloromethyl-5-(1-naphthyl)- 
benzophenone 1,3,4-oxadiazole 
4,4'-bis(diethylamino)- 
" 2-trichloromethyl-5-(4-chloro- 
benzophenone phenyl)-1,3,4-oxadiazole 
4,4'-bis(diethylamino)- 
" 2-trichloromethyl-5-(4-chloro- 
benzophenone styryl)-1,3,4-oxadiazole 
4,4'-bis(diethylamino)- 
" 2,4,6-tris(trichloromethyl)-s- 
benzophenone triazine 
4,4'-bis(diethylamino)- 
" 2-trichloromethylquinazoline 
benzophenone 
4,4'-bis(diethylamino)- 
2,4-dimethylthioxanthone 
phenyltribromomethylsulfone 
benzophenone 
4,4'-bis(diethylamino)- 
" 2,4,6-tris(trichloromethyl)-s- 
benzophenone triazine 
4,4'-bis(diethylamino)- 
4-benzoylpyridine 
phenyltribromomethylsulfone 
benzophenone 
4,4'-bis(diethylamino)- 
" 2-trichloromethyl-5-(4-chloro- 
benzophenone phenyl)-1,3,4-oxadiazole 
__________________________________________________________________________ 
Typical examples of preferred polyfunctional monomers to be used in the 
photopolymerizable composition of the invention are as follows: acrylic or 
methacrylic esters of polyols, such as diethylene glycol diacrylate or 
dimethacrylate, triethylene glycol diacrylate or dimethacrylate, 
tetraethylene glycol diacrylate or dimethacrylate, pentaerythritol 
triacrylate or trimethacrylate trimethylolpropane triacrylate or 
trimethacrylate, dipentaerythritol hexaacrylate or hexamethacrylate, 
1,6-hexanediol diacrylate or dimethacrylate, etc.; bisacrylamides or 
methacrylamides such as methylenebisacrylamide or 
methylenebismethacrylamide, ethylenebisacrylamide or 
ethylenebismethacrylamide, etc.; polyfunctional monomers containing a 
urethane group or groups, such as 
di(2-methacryloxyethyl)-2,4-tolylenediurethane and 
di(2-acryloxyethyl)hexamethylenediurethane; and acrylurethane or 
methacrylurethane oligomers obtained by reacting a terminal isocyanate 
group-containing compound (obtained by previously reacting a polyol with a 
diisocyanate) with a .beta.-hydroxyalkyl acrylate or methacrylate. 
These examples are described in Japanese Patent Publication Nos. 5093/60, 
14719/60 and 28729/69 (British Pat. No. 1,154,872). 
The photopolymerizable composition of the present invention contains the 
ternary photopolymerization initiator system and the polyfunctional 
monomer as necessary ingredients. If desired, additional components known 
in the art, such as a high molecular weight binder, a thermal 
polymerization inhibitor, a plasticizer, a dye, a color-changing agent, an 
ethylenically unsaturated compound other than the aforesaid polyfunctional 
monomer, an agent for accelerating adhesion to anodized aluminum or copper 
surface, and other aids may be used to prepare a wide variety of 
lithographic printing plates, resinous letterpresses, photoresists, 
photomasks, etc. 
The above-described high molecular weight binders are those which are used 
for improving printability and physical properties of resists, and 
examples thereof include saturated or unsaturated, modified or 
non-modified alkyd or polyester resins, vinyl resins, acrylic resins, 
epoxy resins, xylene resins, aromatic sulfonamide-formaldehyde resins, 
ketone resins, petroleum resins, diallyl phthalate resins; melamine 
resins, rosin-modified phenol resins, natural resins (e.g., cellulose, 
cellulose derivatives, etc.), and the like. Particularly preferred 
examples thereof include alcohol-soluble nylon, poly(methyl methacrylate), 
methyl methacrylate-methacrylic acid copolymer, etc. 
The thermal polymerization inhibitors are added to inhibit thermal 
polymerization or spontaneous polymerization over a period of time of the 
photopolymerizable composition of the present invention, and examples 
thereof include p-methoxyphenol, hydroquinone, t-butylcatechol, 
pyrogallol, 2-hydroxybenzophenone, 4-methoxy-2-hydroxybenzophenone, 
cuprous chloride, phenothiazine, chloranil, napthylamine, .beta.-naphthol, 
2,6-di-t-butyl-p-cresol, nitrobenzene, dinitrobenzene, picric acid, 
p-toluidine, etc. 
The plasticizers are added for controlling the physical properties of film, 
and examples thereof include phthalic acid esters (e.g., dibutyl 
phthalate, diheptyl phthalate, dioctyl phthalate, diallyl phthalate, 
etc.), glycol esters (e.g., triethylene glycol diacetate, tetraethylene 
glycol diacetate, etc.), phosphoric acid esters (e.g., tricresyl 
phosphate, triphenyl phosphate, etc.), amides (e.g., p-toluenesulfonamide, 
benzenesulfonamide, N-n-butylacetamide, etc.), aliphatic dibasic acid 
esters (e.g., diisobutyl adipate, dioctyl adipate, dimethyl sebacate, 
dioctyl azelate, dibutyl maleate, etc.), triethyl citrate, tributyl 
citrate, glycerin triacetyl ester, butyl laurate, dioctyl 
4,5-diepoxycyclohexane-1,2-dicarboxylate, etc. 
The dyes are exemplified by Brilliant Green, Eosine, Ethyl Violet, 
Erythrosine B, Methyl Green, Crystal Violet, Victoria Pure Blue BOH, Basic 
Fuchsine, Phenolphthalein, 1,3-diphenyltriazine, Alizarine Red S, 
Thymolphthalein, Methyl Violet 2B, Quinaldine Red, Rose Bengale, Metanil 
Yellow, Thymolsulfophthalein, Xylenol Blue, Methyl Orange, Orange IV, 
diphenylthiocarbazone, 2,7-dichlorofluorescein, Paramethyl Red, Congo Red, 
Benzopurpurin 4B, .alpha.-Naphthyl Red, Nile Blue A, phenacetaline, Methyl 
Violet, Malachite Green, Parafuchsine, Oil Blue #603 (made by Orient 
Kagaku Kogyo K.K.), Rhodamine B, Rhodamine 6G, etc. 
The color-changing agents are added to the photopolymerizable composition 
so as to provide a visible image upon exposure. Specific examples thereof 
include diphenylamine, dibenzylaniline, triphenylamine, diethylaniline, 
diphenyl-p-phenylenediamine, p-toluidine, 4,4'-biphenyldiamine, 
o-chloroaniline, p,p',p"-hexamethyltriaminotriphenylmethane, 
p,p'-tetramethyldiaminotriphenylmethane, 
p,p',p"-triaminotriphenylcarbinol, etc., in addition to the aforesaid 
dyes. 
Specific examples of the ethylenically unsaturated compounds other than the 
foregoing polyfunctional monomers include ethylene glycol monoacrylate or 
monomethacrylate, triethylene glycol methyl ether acrylate or 
methacrylate, ethylene glycol phenyl ether acrylate or methacrylate, 
tetraethylene glycol monoacrylate or monomethacrylate, 
diacetoneacrylamide, acrylamide, methacrylamide, N-n-butylacrylamide or 
methacrylamide, etc. 
Specific examples of the adhesion-accelerating agents include those 
described in Japanese Patent Publication No. 9177/75 (U.S. Pat. No. 
3,645,772), such as benzimidazole, benzothiazole, benzoxazole, 
benzotriazole, etc., and those described in Japanese Patent Application 
(OPI) No. 702/78, such as 2-mercaptobenzothiazole, 
2-mercaptobenzimidazole, etc. 
Preferred proportions and particularly preferred proportions of the 
foregoing constituents are given below based on 100 parts by weight of the 
polyfunctional monomer. 
______________________________________ 
Particularly 
Preferred 
Preferred 
Range Range 
______________________________________ 
Compound (I) 0.01-100 (0.1-50) 
Compound (IIa) or (IIb) 
0.01-100 (0.1-50) 
Compound (III) 0.01-100 (0.1-50) 
High molecular weight binder 
0-10,000 
(0-1,000) 
Thermal polymerization 
0-50 (0-20) 
inhibitor 
Plasticizer 0-1,000 (0-100) 
Dye 0-100 (0-50) 
Color-changing agent 
0-100 (0-50) 
Ethylenically unsaturated 
0-1,000 (0-100) 
compound 
Adhesion-accelerating 
0-50 (0-20) 
agent 
______________________________________ 
The photopolymerizable composition of the present invention is prepared by 
dissolving the aforesaid constituents in a proper solvent and coating the 
resulting solution on a desired support in a known manner. The solvent 
selected is not unduly limited, and may be freely selected from those 
known in the art. As the solvent, ethylene dichloride, monochlorobenzene, 
cyclohexanone, methyl ethyl ketone, acetone, methyl cellosolve acetate, 
ethyl acetate, methyl acetate, methyl cellosolve, toluene, xylene, etc., 
may be used alone or in combination. 
The photopolymerizable composition of the present invention may be 
advantageously used as a photoresist layer of a dry film resist. When used 
as the photoresist layer, the composition is coated in a thickness of 
about 0.1.mu. to 500.mu., particularly preferably about 1.mu. to 200.mu.. 
In the case of using the photopolymerizable composition of the present 
invention to prepare presensitized lithographic plates, the composition is 
applied to form a coating when dry in an amount of about 0.1 to 10.0 
g/m.sup.2 and, particularly preferably, about 0.5 to 5.0 g/m.sup.2. 
The support selected is not unduly limited, and may be freely selected from 
a wide variety of supports known in the art depending on the intended use 
of the resulting light-sensitive material. 
In using the photopolymerizable composition of the present invention as a 
dry film resist, preferred supports are selected from among polyamides, 
polyolefins, polyesters, vinyl polymers, cellulose esters, etc., of about 
3.mu. to 100.mu. in thickness. Particularly preferred supports are 
transparent polyethylene terephthalate films of about 25.mu. in thickness. 
In addition, a suitable protective film may also be used, such as a 
polyolefinic film of preferably about 20 to 25.mu. in thickness. 
In using the photopolymerizable composition of the present invention for 
producing films for photomasks, a polyethylene terephthalate film having 
vacuum-deposited thereon aluminum, aluminum alloy or chromium, and 
polyethylene terephthalate films having provided thereon a colored layer 
are suitably used as supports. 
When the photopolymerizable composition of the present invention is used in 
a light-sensitive layer of a presensitized lithographic plate, suitable 
supports include aluminum plates which are rendered hydrophilic, such as 
silicate-treated aluminum plates, anodized aluminum plates, grained 
aluminum plates, and silicate-electrodeposited aluminum plates and, in 
addition, zinc plates, stainless steel plates, chromium-treated copper 
plates, and plastic film or paper which are rendered hydrophilic. 
As supports used when the photopolymerizable composition of the present 
invention is used for producing color proofs for printing, films for 
overhead projectors, or films for preparing second originals, typical 
examples include transparent films such as polyethylene terephthalate 
film, cellulose triacetate film, etc., and chemically or physically 
surface-matted films thereof. 
The ternary photopolymerization initiator system of the present invention 
shows a surprisingly enhanced sensitivity and high photo-hardened film 
strength. As a result, when used as dry film resist, the composition of 
the present invention provides a "tent" having remarkably enhanced spray 
impact resistance, thus improving the reliability of the "tent". When used 
for making lithographic printing plates, printing life is remarkably 
improved, thus reducing plate-making costs. Further, when used as a 
light-sensitive layer for photomask or color proof, it provides an 
enhanced image, providing prolonged photomask or color proof life. In 
addition, the resulting film of high strength is remarkably durable and 
does not require excessive care in handling, leading to improved working 
efficiency. 
Excellent development characteristics of the photopolymerizable composition 
of the present invention prevent the formation of scums and printing 
stains. 
Dry film resists or light-sensitive materials such as presensitized plates 
or color proofs using the photopolymerizable composition of the present 
invention have a good storage life due to the good stability of the 
composition. 
The ternary photopolymerization initiator system of the present invention 
also has a high ability to change the color of a leuco dye or other dye 
included in the composition with light, and hence can impart print-out 
properties to the photoresist or presensitized lithographic plate.

The present invention will now be described in more detail by reference to 
examples of preferred embodiments of the present invention which, however, 
are not to be construed as limiting the present invention in any way. 
Unless otherwise indicated herein, all percents, parts and ratios are by 
weight. 
EXAMPLE 1 
The following coating solutions containing the various photopolymerizable 
initiators shown in Table 1 and other common components shown were 
prepared. 
______________________________________ 
Poly(methyl methacrylate) 
15 g 
(weight average molecular weight: 
140,000) 
Trimethylolpropane Triacrylate 
2.4 g 
Tetraethylene Glycol Diacrylate 
6.1 g 
Photopolymerization Initiator System 
x g 
p-Methoxyphenol 0.01 g 
p-Toluenesulfonamide 1.62 g 
Malachite Green 0.015 g 
Methyl Ethyl Ketone 45 g 
______________________________________ 
Each of the coating solutions was coated on a polyethylene terephthalate 
film (25.mu. thick), then dried in a 100.degree. C. oven for 2 minutes to 
form about 50.mu. thick coat. Each of the resulting coated supports was 
laminated on its coated side on a copper-clad laminate at 120.degree. C. 
Then, a step wedge of 0.15 in optical density difference was superposed 
thereon, and the laminate structure was exposed under reduced pressure of 
about 10 mm Hg for 80 counts using a 2 kw super-high pressure mercury lamp 
(made by Orc Manuf. Co., Ltd.; jet printer). After delaminating the 
polyethylene terephthalate supports from the exposed laminates, the 
laminates were immersed in 1,1,1-trichloroethane for 60 seconds to 
dissolve away unexposed portions. The light sensitivities of each 
photopolymerizable composition was then determined by reading clear step 
number of the thus-obtained step wedge image. 
In a second experiment, a 25.mu. thick polyethylene film was laminated on 
the unexposed coats of samples prepared as described above and coated on 
polyethylene terephthalate films. 10 mm.times.70 mm pieces were cut out of 
the resulting sandwich-like laminates, and were evenly exposed for 20 
counts using a 2 kw super-high pressure mercury lamp (made by Orc Manuf. 
Co., Ltd.; jet printer). 30 Minutes after the exposure, the polyethylene 
film and polyethylene terephthalate film were delaminated from the 
laminates to produce photo-hardened films. Each of the hardened films was 
mounted on a tensile tester to measure its stress-strain curve. Tensile 
strength of the films was evaluated in terms of yield stress with 20 count 
exposure. 
Results thus-obtained are tabulated in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Three Compounds: 4,4'-Bis(diethylamino)benzophenone, Xanthone, 
Phenyltribromomethylsulfone 
Amount Yield 
Photopolymerization 
Added 
Sensitivity 
Stress 
Film No. Initiator System (.times. g) 
(step) 
(kg/cm) 
__________________________________________________________________________ 
1 (Invention) 
4,4'-Bis(diethylamino)benzophenone 
0.04 
(ternary) 
Xanthone 0.16 12 1.20 
Phenyltribromomethylsulfone 
0.37 
2 (Comparison) 
4,4'-Bis(diethylamino)benzophenone 
0.04 No image 
-- 
(single compound) 
3 (Comparison) 
Xanthone 0.16 No image 
-- 
(single compound) 
4 (Comparison) 
Phenyltribromomethylsulfone 
0.37 No image 
-- 
(single compound) 
5 (Comparison) 
4,4'-Bis(diethylamino)benzophenone 
0.04 8 0.25 
(binary) Xanthone 0.16 
6 (Comparison) 
4,4'-Bis(diethylamino)benzophenone 
0.04 9 0.51 
(binary) Phenyltribromomethylsulfone 
0.37 
7 (Comparison) 
Xanthone 0.16 No image 
-- 
(binary) Phenyltribromomethylsulfone 
0.37 
__________________________________________________________________________ 
As is clear from Table 1, the film sample containing the ternary 
polymerization initiator system in accordance with the present invention 
(Film No. 1) is superior to film samples using each element thereof 
independently (Film Nos. 2 to 4) and to film samples using binary systems 
thereof (Film Nos. 5 to 7) in both sensitivity and yield stress. 
EXAMPLE 2 
Photopolymerizable coatings were prepared, exposed and evaluated in the 
same manner as in Example 1 using the photopolymerization initiator 
systems shown in Table 2, and sensitivity and yield stress were measured 
as in Example 1 giving the values shown in Table 2. 
In every case, the use of the ternary photopolymerization system in 
accordance with the present invention resulted a coat with remarkably 
higher sensitivity and larger yield stress than the corresponding binary 
system. 
TABLE 2 
__________________________________________________________________________ 
Amount Yield 
Photopolymerization 
Added 
Sensitivity 
Stress 
Film No. Initiator System (.times. g) 
(step) 
(kg/cm) 
__________________________________________________________________________ 
1 (Invention) 
4,4'-Bis(diethylamino)benzophenone 
0.04 
Thioxanthone 0.17 9.5 0.32 
Phenyltribromomethylsulfone 
0.37 
2 (Comparison) 
Phenyltribromomethylsulfone was 
8 0.20 
removed from Film No. 1. 
3 (Invention) 
4,4'-Bis(diethylamino)benzophenone 
0.04 
2-Chlorothioxanthone 
0.20 10.5 0.31 
Phenyltribromomethylsulfone 
0.37 
4 (Comparison) 
Phenyltribromomethylsulfone was 
8 0.23 
removed from Film No. 3 
5 (Invention) 
4,4'-Bis(diethylamino)benzophenone 
0.04 
9-Fluorenone 0.15 10.5 0.41 
Phenyltribromomethylsulfone 
0.37 
6 (Comparison) 
Phenyltribromomethylsulfone was 
8 0.13 
removed from Film No. 5. 
7 (Invention) 
4,4'-Bis(diethylamino)benzophenone 
0.04 
2-tert-Butylanthraquinone 
0.22 10 0.79 
Phenyltribromomethylsulfone 
0.37 
8 (Comparison) 
Phenyltribromomethylsulfone was 
6 0.27 
removed from Film No. 7. 
9 (Invention) 
4,4'-Bis(diethylamino)benzophenone 
0.04 
2-Benzoylpyridine 
0.15 13 0.43 
Phenyltribromomethylsulfone 
0.37 
10 (Comparison) 
Phenyltribromomethylsulfone was 
9.5 0.08 
removed from Film No. 9. 
11 (Invention) 
4,4'-Bis(diethylamino)benzophenone 
0.04 
3-Benzoylpyridine 
0.15 13 0.54 
Phenyltribromomethylsulfone 
0.37 
12 (Comparison) 
Phenyltribromomethylsulfone was 
9.5 0.27 
removed from Film No. 11. 
13 (Invention) 
4,4'-Bis(diethylamino)benzophenone 
0.04 
4-Benzoylpyridine 
0.15 12 0.75 
Phenyltribromomethylsulfone 
0.37 
14 (Comparison) 
Phenyltribromomethylsulfone was 
9.5 0.12 
removed from Film No. 13. 
__________________________________________________________________________ 
EXAMPLE 3 
Preparation of a Printed-Wiring Board 
Sandwich-like laminates (Film Nos. 1 to 7) were prepared according to the 
process described in Example 1, comprising a polyethylene terephthalate 
film support (25.mu. thick), a photopolymerizable layer (50.mu. thick), 
and a polyethylene film (25.mu. thick). The polyethylene film was 
delaminated from each of the laminates, which were then laminated at 
120.degree. C. on both sides of an affinitized and dried copper-clad 
laminate (having 100 each of perforations of 2.5 mm, 1.5 mm, and 1.0 mm in 
diameter) using an A-24 laminator. Photomasks of 3.0 mm, 2.0 mm, and 1.4 
mm in land diameter were superimposed on respective laminates in alignment 
with the perforations, the laminates were exposed through the photomasks 
using a super-high pressure mercury lamp (20 counts) to produce 
photo-hardened resist films on both sides of the respective perforations. 
The polyethylene terephthalate film supports were removed from the 
respective laminates, and unexposed resist portions were removed by 
developing the laminates by spraying them with 1,1,1-trichloroethane. With 
the resists prepared using Film 1 of the invention and Comparison Films 5 
and 6, the respective perforations were covered with photo-hardened film 
("tent"). No "tent" resulted using Comparison Films 2, 3, 4 and 7. No 
defects were observed in any "tent". Then, the thus-developed laminates 
were subjected to a high pressure hot water spray (54.degree. C.) to test 
the spray impact resistance of the resulting "tent". The number of "tents" 
destroyed during the spraying are given in Table 3. 
TABLE 3 
______________________________________ 
Tents Destroyed by Application 
of High-Pressure Spray (%) 
Perforation Perforation 
Perforation 
Diameter Diameter Diameter 
Film No. 2.5 mm 1.5 mm 1 mm 
______________________________________ 
1 4 1 0 
(Invention) 
5 85 80 65 
(Comparative 
Sample 4) 
6 30 13 10 
(Comparative 
Sample 5) 
______________________________________ 
It is clear from Table 3 that the composition of the present invention 
containing the ternary photopolymerization initiator system had high 
sensitivity and provided tents which were substantially more durable than 
those given by the compositions containing a single initiator or a binary 
photopolymerization initiator system. 
EXAMPLE 4 
Preparation of a Negative-Working Presensitized Lithographic Plate 
On a surface-grained and anodized 0.15 mm thick aluminum plate the 
following light-sensitive solution was coated using a whirler, and then 
dried at 100.degree. C. for 2 minutes to prepare a presensitized plate. 
______________________________________ 
Trimethylolpropane Triacrylate 
0.38 g 
Methyl Methacrylate/Methacrylic Acid 
0.62 g 
(90 mols/10 mols) Copolymer (weight 
average molecular weight: 120,000) 
Michler's Ketone 0.04 g 
Xanthone 0.02 g 
Tribromomethylphenylsulfone 
0.02 g 
Oil Blue #603 0.010 g 
p-Methoxyphenol 0.001 g 
Leucocrystal Violet 0.008 g 
Methyl Cellosolve Acetate 5 g 
Methyl Ethyl Ketone 5 g 
______________________________________ 
This presensitized lithographic plate was imagewise exposed using a 2 kw 
super-high pressure mercury lamp (made by Orc Manuf. Co., Ltd.; jet 
printer) for 20 counts, and developed with a developer composed of 1.2 g 
of caustic soda, 300 ml of isopropyl alcohol, and 900 ml of water to 
remove unexposed areas to produce a lithographic printing plate. 
When the thus-obtained printing plate was printed using a printing press, 
350,000 distinct copies were obtained. 
While the invention has been described in detail and with reference to 
specific embodiments thereof, it will be apparent to one skilled in the 
art that various changes and modifications can be made therein without 
departing from the spirit and scope thereof.