Curable composition for back-protecting material in making shadow mask

The present invention provides a curable composition for back-protecting material used in making shadow masks which gives a cured film excellent in all of etching resistance, alkali solubility or peelability, and pattern formability even when a second etching is carried out at high temperatures. That is, the present invention provides a curable composition for back-protecting material used at a second etching step in making shadow masks which comprises the following components (a), (b) and (c) and which gives a cured film having alkali solubility or alkali peelability: PA1 (a) a compound having one carboxyl group and one (meth)acryloyl group, PA1 (b) a tri(meth)acrylate of an alkylene oxide adduct of isocyanuric acid, and PA1 (c) (c1) a (meth)acrylate compound having two or more (meth)acryloyl groups, (c2) a chain transfer agent, or a combination of (c1) and (c2).

FIELD OF THE INVENTION 
The present invention relates to a composition for back-protecting 
materials used at a second etching step in making shadow masks, said 
composition having such characteristics that it can be coated on the 
surface of a metal plate having fine dents without forming bubbles, and 
can be cured by heating or irradiation with active energy rays such as 
ultraviolet rays and electron beams, and it can give a cured film having 
corrosion resistance against acid treatment, and having solubility or 
peelability with alkali treatment. 
DESCRIPTION OF RELATED ART 
A shadow mask has a function to collide electrons emitted from an electron 
gun in a Braun tube for color television against the phosphor of a 
particular color, and it is a thin metal plate provided with many fine 
holes such as rectangular holes, narrow rectangular holes (aperture grill 
type) or circular holes which are formed in a given pattern by etching. 
Of these shadow masks, those which have circular holes are used for CRT in 
personal computers or the like, and those which have narrow rectangular 
holes (aperture grill type) are used for high-resolution or high-luminance 
televisions. These shadow masks are demanded to have fine and highly 
accurate holes. In making these shadow masks, dents are made by a first 
etching on the front and back sides of a metal plate at the corresponding 
positions. A cured film of a back-protecting material is formed on one 
side of the metal plate, followed by carrying out a second etching to 
allow the corresponding dents to communicate with each other at their 
bottoms. 
The outline of the production process of shadow masks will be explained. 
First, a photosensitive resin is coated on both the front and back sides 
of a thin metal plate of iron or the like. Then, a negative film having a 
pattern is brought into close contact with the metal plate, and these are 
subjected to photographic printing to cure the exposed portions of the 
photosensitive resin, followed by development to remove the unexposed 
portions of the photosensitive resin. 
Thereafter, a first etching is carried out with an etching solution such as 
iron trichloride to form fine dents on both the front and back sides which 
do not communicate with each other between the front and back sides. A 
composition for back-protecting material is coated on only one side of the 
metal plate after subjected to the first etching, and the composition is 
cured by irradiation with active energy rays such as ultraviolet rays or 
by heating to form a cured film which fills up the fine dents on the one 
side of the metal plate. 
After the one side is protected in this way, a second etching for the dents 
on the other side is carried out with an etching solution to allow the 
dents on the one side formed by the first etching and the dents on the 
other side to communicate with each other at their bottoms. Then, the 
cured film of the photosensitive resin for the formation of patterns and 
that of the composition for back-protecting material are removed by alkali 
treatment to obtain a shadow mask. 
The second etching using the composition for back-protecting material can 
solve the problem of reduction in accuracy of holes which is caused by the 
presence of abnormally large holes or irregular holes formed when the 
holes are made only by the first etching. 
In the above process for production of shadow masks, the composition for 
back-protecting material which is used after the first etching, must 
satisfy the following characteristics 1-6. 
1 Dent-filling property: A property capable of uniformly wetting the 
surface of a material having hemispherical dents having a diameter of 
50-200 .mu.m or narrow rectangular dents having a width of 50-200 .mu.m 
and a length of 10-200 cm and filling the dents without forming bubbles in 
the dents. 
2 Surface smoothness: This is the property that bubbles generated by a 
slight gas produced when the composition for back-protecting material 
fills the circular or narrow rectangular dents, do not remain in the resin 
surface layer after cured, and the surface of the cured film is smooth. 
3 Curability: The property of the composition being cured uniformly to the 
bottom of the dent. 
4 Etching resistance: This is the property that the cured film has etching 
resistance against the second etching conducted with an etching solution 
such as iron trichloride, and protects the surface of the coated material. 
5 Alkali solubility: The property of the cured film being easily dissolved 
or peeled by alkali treatment. 
6 Pattern formability: A property capable of forming fine holes faithful to 
the pattern drawn on the negative film (negative pattern) in a thin metal 
plate. For example, in the case of a negative pattern comprising many 
narrow rectangular fine holes formed at a given interval with the longer 
sides of the rectangles being in parallel to each other, the property is 
such that the holes are formed in the metal plate while the regular shapes 
peculiar to the negative pattern are maintained, for example, under the 
conditions that the longer sides are linear, the longer sides of adjacent 
holes are parallel to each other, and the distance between the longer 
sides of adjacent holes is the same, and no distortion occurs in the metal 
portions between the longer sides of the narrow rectangular holes. 
As the composition for back-protecting materials which satisfies the above 
characteristics, there has been used a composition which is prepared by 
dissolving in an organic solvent a resin which forms a film soluble in an 
alkaline liquid. The composition is coated by spraying and other methods, 
and then the organic solvent is evaporated by a warm air drying oven or 
the like to form a resin coated film. However, this composition suffers 
from the problems that 1 since the composition contains the organic 
solvent in a large amount, there are needed a drying oven for the 
evaporation of the organic solvent after coating the composition and an 
apparatus for recovering the evaporated solvent, and 2 since a large 
amount of the organic solvent is evaporated at the time of drying, there 
are dangers of toxicity, ignition and explosion. In order to reduce the 
risks of ignition, explosion and fire at the drying step, use of 
chlorine-based solvents having non-flammability, such as 
trichloroethylene, is investigated, but recently it has been pointed out 
that these solvents cause problems such as air pollution, and use of them 
tends to be prohibited. 
As compositions for back-protecting materials which solve the above 
problems, proposed are, for example, use of aqueous ultraviolet curing 
compositions (JP-A-1-261410 and JP-A-2-133404) and use of substantially 
solventless ultraviolet curing compositions (JP-A-2-110166). 
At present, in the production of shadow masks, it is investigated to carry 
out the etching at high temperatures for the purpose of shortening of the 
steps and/or controlling of the shape of holes by changing the etching 
temperatures. 
However, none of the cured films obtained from conventional compositions 
for back-protecting materials are satisfactory in all of etching 
resistance at high temperatures, solubility in alkali or peelability with 
alkali, and pattern formability. 
That is, when a metal plate after the first etching is subjected to 
back-protecting treatment using a conventional composition and the second 
etching is carried out at high temperatures, the surface of the metal 
plate cannot be sufficiently protected from etching solutions and large 
holes are sometimes formed in the metal plate. On the other hand, when it 
is attempted to improve etching resistance under the high temperature 
etching conditions, alkali solubility of the cured film is conspicuously 
deteriorated, resulting in failure in peeling of the film or deterioration 
of pattern formability. Therefore, the etching temperature cannot be 
further raised, when cured films having all of etching resistance, alkali 
solubility or peelability, and pattern formability are to be obtained 
using conventional compositions. 
OBJECT OF THE INVENTION 
The inventors have conducted an intensive research in an attempt to solve 
the above problems of the conventional compositions for back-protecting 
materials, that is, to find curable compositions for back-protecting 
materials in making shadow masks which give cured films excellent in all 
of etching resistance, alkali solubility or peelability, and pattern 
formability even when the second etching is carried out at high 
temperatures. 
SUMMARY OF THE INVENTION 
That is, the present invention provides a curable composition for 
back-protecting materials used at a second etching step in making shadow 
masks which comprises the following components (a), (b) and (c) and which 
gives a cured film having alkali solubility or alkali peelability: 
(a) a compound having one carboxyl group and one (meth)acryloyl group, 
(b) a tri(meth)acrylate of an alkylene oxide adduct of isocyanuric acid, 
and 
(c) (c1) a (meth)acrylate compound having two or more (meth)acryloyl 
groups, (c2) a chain transfer agent, or a combination of (c1) and (c2).

DETAILED DESCRIPTION OF THE INVENTION 
The present invention will be explained in detail. 
In this specification, acryloyl group or methacryloyl group is expressed by 
"(meth)acryloyl group", acrylate or methacrylate is expressed by 
"(meth)acrylate", and acrylic acid or methacrylic acid is expressed by 
"(meth)acrylic acid". 
1. Curable composition for back-protecting materials in making shadow 
masks. 
1-1 . The Component (a) 
The component (a) is a compound having one carboxyl group and one 
(meth)acryloyl group, and imparts solubility or peelability with alkali 
treatment to the cured film of the composition of the present invention. 
Preferred component (a) includes a reaction product of a dibasic acid or an 
acid anhydride thereof with a (meth)acrylate having a hydroxyl group at an 
end, a reaction product of a lactone with a compound having a carboxyl 
group and a (meth)acryloyl group, or the like. 
With regard to the reaction product of a dibasic acid or an acid anhydride 
thereof with a (meth)acrylate having a hydroxyl group at an end, examples 
of the dibasic acid or acid anhydride thereof are phthalic acid, 
tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid and succinic 
acid, and anhydrides of these dibasic acids. Examples of the 
(meth)acrylate having a hydroxyl group at an end are hydroxyalkyl 
(meth)acrylates such as hydroxyethyl (meth)acrylate and hydroxypropyl 
(meth)acrylate. 
As specific compounds, mention may be made of, for example, 
(meth)acryloyloxyethyl monophthalate (as commercially available products, 
ARONIX M-5400 manufactured by Toagosei Co., Ltd., and others), 
(meth)acryloyloxypropyl monophthalate, (meth)acryloyloxyethyl 
monotetrahydrophthalate, (meth)acryloyloxypropyl monotetrahydrophthalate, 
(meth)acryloyloxyethyl monohexahydrophthalate, (meth)acryloyloxypropyl 
monohexahydrophthalate, (meth)acryloyloxyethyl monosuccinate (as 
commercially available products, ARONIX M-5500 manufactured by Toagosei 
Co., Ltd., and others), (meth)acryloyloxypropyl monosuccinate, 
(meth)acryloyloxyethyl monomaleate, and (meth)acryloyloxypropyl 
monomaleate. 
With regard to the reaction products of a lactone and a compound having a 
carboxyl group and a (meth)acryloyl group, examples of the lactone include 
.epsilon.-caprolactone and others. Examples of the compound having a 
carboxyl group and a (meth)acryloyl group include (meth)acrylic acid and 
others. 
Specific compounds include, for example, compounds having a carboxyl group 
at an end of the molecule which are reaction products of 
.epsilon.-caprolactone and (meth)acrylic acid (as commercially available 
products, ARONIX M-5300 manufactured by Toagosei Co., Ltd., and others). 
As the component (a), mention may be made of compounds such as 
(meth)acrylic acid or the dimer thereof (as commercially available 
products, ARONIX M-5600 manufactured by Toagosei Co., Ltd., and others) in 
addition to the compounds enumerated above. 
Among the above mentioned compounds as component (a), acrylic acid dimer 
and (meth)acryloyloxyethyl monosuccinate are preferred because they per se 
are relatively low in viscosity (200-400 cps at 25.degree. C.) and the 
compositions of the present invention can be of low viscosity. 
The component (a) can comprise two or more compounds in combination. 
Amount of the component (a) is preferably 20-80 weight %, more preferably 
30-70 weight % based on the total weight of all of the component (a), the 
component (b) and the component (c1) or the total weight of all of the 
component (a), the component (b), the component (c1) and other 
(meth)acrylates, if these are added (hereinafter all of these components 
are referred to as "curable components"). If the amount is less than 20 
weight %, alkali solubility or peelability of the cured film of the 
composition is insufficient, and if it is more than 80 weight %, corrosion 
resistance to the second etching is sometimes insufficient. 
1-2. The Component (b) 
The component (b) is a tri(meth)acrylate of an alkylene oxide adduct of 
isocyanuric acid, and this component imparts etching resistance to the 
cured film of the composition at high temperature etching. When the 
composition contains only mono(meth)acrylate or di(meth)acrylate of an 
alkylene oxide adduct of isocyanuric acid, etching resistance is 
deteriorated. 
Examples of the tri(meth)acrylate are those which are represented by the 
following formula (1). 
##STR1## 
wherein A.sup.1, A.sup.2 and A.sup.3 each represent an alkylene group of 
2-4 carbon atoms; R.sup.1, R.sup.2 and R.sup.3 each represent H or 
CH.sub.3 ; A.sup.1, A.sup.2 and A.sup.3, and R.sup.1, R.sup.2 and R.sup.3 
in one molecule may be the same or different, respectively; and l, m and n 
each represent a real number of 0-3.0 with the proviso that they satisfy 
l+m+n.gtoreq.2.0. 
Preferred examples of the component (b) are tri(meth)acrylates of an adduct 
of isocyanuric acid with 3 moles of ethylene oxide which are compounds of 
the formula (1) where A.sup.1, A.sup.2 and A.sup.3 each represent an 
ethylene group, R.sup.1, R.sup.2 and R.sup.3 each represent H or CH.sub.3 
and l, m and n each represent 1 (as commercially available products, 
ARONIX M-315 manufactured by Toagosei Co., Ltd., and others). 
Amount of the component (b) is preferably 5-60 weight % based on the total 
weight of the curable components. If the amount is less than 5 weight %, 
etching resistance of the cured film of the composition is sometimes 
deteriorated, and if it is more than 60 weight %, there is the possibility 
of alkali solubility or peelability of the cured film being insufficient. 
1-3. The Component (c) 
Component (c1) is a (meth)acrylate having two or more (meth)acryloyl groups 
(hereinafter referred to as "poly(meth)acrylate"), and this component 
imparts etching resistance to the cured film of the composition of the 
present invention. Examples of the poly(meth)acrylates include polyol 
poly(meth)acrylates, polyester poly(meth)acrylates, and epoxy 
poly(meth)acrylates. These components will be explained below. 
1 Polyol poly(meth)acrylates: 
These are reaction products of a polyhydric alcohol with (meth)acrylic 
acid, and examples of them are di(meth)acrylates of diols, such as 
butanediol di(meth)acrylate, pentanediol di(meth)acrylate, hexanediol 
di(meth)acrylate, neopentyl glycol di(meth)acrylate, nonanediol 
di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and 
di(meth)acrylates of esterified diol of hydroxypivalic acid and neopentyl 
glycol; di(meth)acrylates of polyether glycols such as polyethylene glycol 
di(meth)acrylate, polypropylene glycol di(meth)acrylate, and 
polytetramethylene glycol di(meth)acrylate; and poly(meth)acrylates of 
polyols such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri- 
or tetra(meth)acrylate, ditrimethylolpropane tri- or tetra(meth)acrylate, 
and dipentaerythritol penta- or hexa(meth)acrylate. 
Furthermore, mention may be made of reaction products of (meth)acrylic acid 
with an adduct of a polyhydric alcohol with an alkylene oxide such as 
ethylene oxide or propylene oxide. Examples thereof are di(meth)acrylates 
of alkylene oxide adducts of hexane diol, di(meth)acrylates of alkylene 
oxide adducts of neopentyl glycol, di(meth)acrylates of alkylene oxide 
adducts of bisphenol A, di(meth)acrylates of alkylene oxide adducts of 
bisphenol F, di(meth)acrylates of alkylene oxide adducts of hydrogenated 
bisphenol A, di(meth)acrylates of alkylene oxide adducts of hydrogenated 
bisphenol F, tri(meth)acrylates of alkylene oxide adducts of 
trimethylolpropane, tri- or tetra(meth)acrylates of alkylene oxide adducts 
of pentaerythritol, and di(meth)acrylates of alkylene oxide adducts of 
tricyclodecane dimethanol. 
2 Polyester poly(meth)acrylates: 
As the polyester poly(meth)acrylates, mention may be made of reaction 
products of polyester type polyhydric alcohols with (meth)acrylic acid. 
Examples of the polyester type polyhydric alcohols are polyester alcohols 
obtained by reacting polybasic acids such as succinic acid, maleic acid, 
adipic acid, sebacic acid, phthalic acid, tetrahydrophthalic acid, 
hexahydrophthalic acid and trimellitic acid, or anhydrides thereof with 
ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 
dipropylene glycol, tripropylene glycol, butanediol, neopentyl glycol, 
pentanediol, hexanediol, nonanediol, trimethylolpropane, glycerin, or 
pentaerythritol. 
3 Epoxy poly(meth)acrylates: 
They are compounds obtained by reacting epoxy groups of epoxy compounds 
having two or more epoxy groups in the molecule with (meth)acrylic acid. 
Examples of these epoxy compounds are diepoxy compound of bisphenol A, 
polyvalent epoxy compounds of phenolic novolak and polyvalent epoxy 
compounds of cresol novolak. 
In addition to the above-mentioned compounds, poly(meth)acrylates include 
phosphoric acid poly(meth)acrylates obtained by reacting acids such as 
phosphoric acid with (meth)acrylates having an end hydroxyl group. 
As the compounds of the component (c1), preferred are diacrylate of 
tripropylene glycol, diacrylate of an ethylene oxide adduct of bisphenol 
A, diacrylate of esterified diol prepared from neopentyl glycol and 
hydroxypivalic acid, diacrylate of tricyclodecane dimethanol, triacrylate 
of trimethylolpropane, and triacrylate of pentaerythritol. 
Amount of the component (c1) is preferably 3-40 weight % based on the total 
weight of the curable components. If the amount is less than 3 weight %, 
etching resistance is sometimes deteriorated, and if it is more than 40 
weight %, there is the possibility of the cured film being insufficient in 
alkali solubility or peelability. 
The component (c2) is a chain transfer agent, which gives alkali solubility 
or peelability and pattern formability to the cured film of the 
composition. 
Various compounds known in the art can be used as the chain transfer agent, 
and monothiol compounds are preferred. The monothiol compounds include, 
for example, mercaptans such as octylmercaptan, nonylmercaptan, 
decylmercaptan, dodecylmercaptan, and cetylmercaptan; hydroxyl 
group-substituted mercaptans such as monothioethylene glycol and 
.alpha.-monothioglycerin; and mercaptocarboxylic acids such as 
mercaptopropionic acid, 2-mercaptopropionic acid, thiolactic acid, and 
thiomalic acid. 
Amount of the component (c2) is preferably 0.01-5 parts by weight, more 
preferably 0.1-3 parts by weight (hereinafter the term "part(s)" means 
"part(s) by weight") for 100 parts in total of the curable components. If 
the amount is less than 0.01 part, the cured film is insufficient in 
alkali solubility or peelability, which may cause non-uniform intervals 
between holes formed in the metal plate or distortion of the metal 
portions between adjacent holes. If it is more than 5 parts, there may 
occur reduction in stability of the composition and increase in viscosity 
of the composition. 
Viscosity at 25.degree. C. of the composition of the present invention is 
preferably 10,000 cps or lower, more preferably 5,000 cps or lower. If the 
viscosity at 25.degree. C. of the composition is higher than 10,000 cps, 
it sometimes becomes difficult to uniformly wet the surface of the metal 
material having dents to fill up the dents. The viscosity of the 
composition can easily be adjusted by suitably selecting the kinds and 
amounts of the above various components or by adding the following other 
components. 
1-4. Other Components 
The composition of the present invention comprises the above components 
(a), (b) and (c) as essential components, and, if necessary, may 
additionally contain a leveling agent, a polymerization initiator, a 
(meth)acrylate other than the components (a), (b) and (c1), and others 
which are referred to below. 
These components will be explained. 
1-4-1. Leveling Agent 
It is preferred that the composition of the present invention additionally 
contains a leveling agent for improving the dent-filling property of the 
composition and the surface smoothness of the cured film. As the leveling 
agent, general surface active agents can be used. 
As examples thereof, mention may be made of FLORAD FC-430 (manufactured by 
Sumitomo 3M Co., Ltd.), MEGAFACK F-177 (manufactured by Dainippon Ink & 
Chemicals Inc.) and MEGAFACK F-179 (manufactured by Dainippon Ink & 
Chemicals Inc.) which are nonionic fluorinated alkyl esters, and NUC 
SILICONE L 7002 (manufactured by Nippon Unicar Co., Ltd.) and FZ-2165 
(manufactured by Nippon Unicar Co., Ltd.) which are silicone compounds. 
Of the above compounds, MEGAFACK F-179 and NUC SILICONE L 7002 are 
preferred because these are less in formation of bubbles and a resin 
coating film excellent in surface smoothness can be easily obtained. 
Amount of the leveling agent added is preferably 0.01-5 parts for 100 parts 
in total of the curable components. If the amount is less than 0.01 part, 
it sometimes becomes difficult to impart the characteristics of 
dent-filling property and surface smoothness to the composition, and if it 
exceeds 5 parts, defects are apt to occur in the resin coating film. 
1-4-2. Polymerization Initiator 
The composition of the present invention can be cured by irradiation with 
active energy rays such as ultraviolet rays, visible rays and electron 
beams, or by heating, and the composition can be cured in a short time by 
adding the following components depending on the curing method. 
When the composition is cured in a short time by irradiation with 
ultraviolet rays or visible rays, the following generally employed 
photopolymerization initiators and sensitizers are used to sufficiently 
exhibit the photocurability of the composition. 
Examples of preferred photopolymerization initiators are 
2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propanone (IRGACURE-907 
manufactured by Ciba-Geigy Corp.), benzyldimethyl ketal (IRGACURE-651 
manufactured by Ciba-Geigy Corp.), 1-hydroxycyclohexylphenyl ketone 
(IRGACURE-184 manufactured by Ciba-Geigy Corp.), diethoxyacetophenone 
(FASTCURE-DEAP manufactured by Fast Chemical Co., Ltd.), 
2-hydroxy-2-methyl-1-phenylpropane-1-one (DALOCURE-1173 manufactured by 
Ciba-Geigy Corp.), 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl) ketone 
(IRGACURE-2959 manufactured by Ciba-Geigy Corp.), and 
2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone (IRGACURE-369 
manufactured by Ciba-Geigy Corp.) as acetophenone photopolymerization 
initiators; benzoin, benzoinmethyl ether, benzoinethyl ether, 
benzoinisopropyl ether, and benzoinisobutyl ether as benzoin ether 
photopolymerization initiators; benzophenone, methyl o-benzoylbenzoate, 
4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, and 
2,4,6-trimethylbenzophenone as benzophenone photopolymerization 
initiators; 2-isopropylthioxantone, 2,4-diethylthioxanthone, 
2,4-dichlorothioxanthone, and 1-chloro-4-propoxythioxanthone as 
thioxanthone photopolymerization initiators; and 
2,4,6-trimethylbenzoyldiphenylphosphine oxide and 
bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide as 
acylphosphine oxide photopolymerization initiators. Moreover, 
camphorquinone and others can be used. 
Examples of preferred sensitizers are triethanolamine, 
methyldiethanolamine, triisopropanolamine, methyl 4-dimethylaminobenzoate, 
ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 
4,4-dimethylaminobenzophenone, and 4,4-diethylaminobenzophenone. 
Among these photopolymerization initiators, acylphosphine oxide 
photopolymerization initiators and/or 1-hydroxycyclohexylphenyl ketone are 
preferred since these can improve pattern formability and prevent 
occurrence of defects such as formation of abnormally large holes in metal 
plate in making shadow masks. 
When the composition is cured mainly by heat energy sources such as heating 
oven, infrared rays and microwave, it is preferred to add 
thermal-polymerization initiators. Suitable thermal-polymerization 
initiators include, for example, azo compounds such as 
azoisobutyronitrile, various organic peroxides such as ketone peroxides, 
hydroperoxides, alkyl peroxides, acyl peroxides, and peroxy esters, and 
inorganic peroxides such as ammonium persulfate. 
When the heating is carried out at relatively low temperatures of 
100.degree. C. or lower or by leaving the composition at room temperature, 
it is preferred to add polymerization accelerators together with the 
thermal-polymerization initiators. Examples of preferred polymerization 
accelerators are organometallic salts of metals such as cobalt, iron and 
manganese with naphthenic acid, linolic acid or acetylacetone, reducing 
amines such as dimethylparatoluidine and ascorbic acid, and other reducing 
substances. 
These polymerization accelerators are used in combination of, for example, 
hydroperoxides, ketone peroxides or peroxy esters with organometallic 
salts, or acyl peroxides with reducing amines. 
Amount of the polymerization initiators is preferably 0.1-15 parts, more 
preferably 0.5-10 parts for 100 parts in total of the curable components. 
If the amount is less than 0.1 part, the effect to accelerate the 
initiation of polymerization is insufficient, and if it exceeds 15 parts, 
amount of the components truly necessary for cured film is reduced, and 
the desired characteristics of the cured film is sometimes deteriorated. 
As mentioned above, the composition of the present invention can be cured 
by either of active energy rays or heating, but irradiation with active 
energy rays is preferred because curing can be performed at a high energy 
efficiency and space for an equipment of energy source can be saved. 
1-4-3. (Meth)acrylates Other Than the Components (a), (b) and (c1) 
If necessary, (meth)acrylates having one (meth)acryloyl group (hereinafter 
referred to as "monofunctional (meth)acrylates") can be added to the 
composition of the present invention in order to adjust viscosity of the 
composition and alkali solubility or peelability of the cured film. 
Examples of preferred monofunctional (meth)acrylates are alkyl 
(meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, 
propyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl 
(meth)acrylate; hydroxyalkyl (meth)acrylates such as hydroxyethyl 
(meth)acrylate and hydroxypropyl (meth)acrylate; (meth)acrylamides such as 
(meth)acrylamide, diacetone (meth)acrylamide, and dimethyl 
(meth)acrylamide; monoalkyl (C.sub.1-9) ether mono(meth)acrylates of 
polyalkylene glycols such as polyethylene glycol and polypropylene glycol; 
polyalkylene glycol mono(meth)acrylates such as polyethylene glycol 
mono(meth)acrylate and polypropylene glycol mono (meth)acrylate; mono 
(meth)acrylates of alkylene oxide adducts of phenols such as 
mono(meth)acrylate of an ethylene oxide or propylene oxide adduct of 
phenol, mono(meth)acrylate of an ethylene oxide or propylene oxide adduct 
of nonylphenol, and mono(meth)acrylate of an ethylene oxide or propylene 
oxide adduct of p-cumylphenol; benzyl (meth)acrylate; 
(meth)acryloylmorpholine; tetrahydrofurfuryl (meth)acrylate; isobornyl 
(meth)acrylate; and compounds represented by the following formulas (2) 
and (3). At least one of them can be used. 
##STR2## 
In the formulas (2) and (3), R.sup.4 and R.sup.5 each represent H or 
CH.sub.3. 
Amount of the monofunctional (meth)acrylates is preferably 0-40 weight % 
based on the total weight of the curable components. 
1-4-4. Other Components 
In addition, water or organic solvents can be added to the composition of 
the present invention in order to lower the viscosity of the composition. 
Examples of the organic solvents are alcohols such as methanol, ethanol, 
butanol, and isopropyl alcohol; cellosolves such as butyl cellosolve, 
methyl cellosolve and ethyl cellosolve; cellosolve acetates such as methyl 
cellosolve acetate, ethyl cellosolve acetate and butyl cellosolve acetate; 
propylene glycol monomethyl ether; toluene; and xylene. 
Amount of the organic solvents is preferably 0-10 parts for 100 parts in 
total of the curable components. 
Furthermore, polymers soluble in the curable components and having a 
molecular weight of 1000-100000, or particulate fillers insoluble in the 
curable components can be added in order to relax the strain at the time 
of curing. 
The composition of the present invention can be obtained by uniformly 
mixing the above components by a usual mixing method, and there are no 
limitations in the sequence of mixing and the mixing apparatus. However, 
the components can be heated to a temperature at which they are molten or 
dispersed, and then mixed in place of mixing the components which are 
solid at room temperature. 
2. Method for Production of Shadow Mask 
The composition of the present invention can be applied to both the 
production of a shadow mask having many circular holes and the production 
of a shadow mask having many narrow rectangular holes, and it can be 
especially preferably used for the production of a shadow mask having many 
narrow rectangular holes (aperture grill type). 
Production method of a shadow mask will be explained below. 
First, a photosensitive resin such as casein or polyvinyl alcohol is coated 
on both the front and back sides of a thin metal plate of iron or the 
like. Then, a negative film provided with a pattern is brought into close 
contact with the metal plate, and photographic printing is carried out to 
cure the exposed portion of the photosensitive resin, followed by 
development treatment to remove the unexposed portion of the 
photosensitive resin. 
Then, a first etching is carried out with an etching solution such as iron 
trichloride to form fine dents which do not communicate with each other 
between the front and back sides. 
A composition for back-protecting material is coated on one side of the 
metal plate after subjected to the first etching, and the composition is 
cured by irradiation with active energy rays such as ultraviolet rays or 
by heating. In this case, the composition can be coated by conventional 
coating methods such as spray coating, flow coating, roll coating, die 
coating and dip coating. 
After the curing step of the composition for back-protecting material, an 
etching solution is supplied to the metal plate, and a second etching is 
carried out for the dents on the other side of the metal plate to allow 
the dents on the one side formed by the first etching and the dents on the 
other side to communicate with each other at their bottoms. Temperature 
for the second etching is usually 40-90.degree. C. As mentioned above, 
since the composition of the present invention has both the etching 
resistance and the alkali solubility or peelability for the second etching 
at high temperatures, the composition is also suitably applicable to the 
second etching at high temperatures of 70-90.degree. C. 
An alkali solution is supplied to the resulting metal plate having many 
holes to dissolve or peel from the metal plate the film of the 
photosensitive resin and the cured film of the composition for 
back-protecting material. In this case, an aqueous solution of NaOH, KOH 
or the like can be used as the alkali solution. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will be explained more specifically by the following 
examples and comparative examples, in which "part(s)" means "part(s) by 
weight". 
Examples 1-3 
A composition for back-protection material curable with active energy rays 
was prepared by dissolving and mixing the components shown in Table 1. 
The resulting composition was coated at a film thickness of 30 .mu.m on a 
test iron plate referred to in the following evaluation method (1). The 
coat was irradiated with ultraviolet rays using a condenser-type metal 
halide lamp of 80 w/cm, and curing of the resin was ascertained by the 
fact that the surface of the coat had no tack. The resulting cured film 
was evaluated on dent-filling property, surface smoothness, etching 
resistance, alkali solubility or peelability, and pattern formability by 
the following methods. The results are shown in Table 2. 
Evaluation Methods 
(1) Dent-Filling Property 
A negative pattern was formed on both sides of an iron plate using a casein 
photosensitive resin, and many narrow rectangular dents were formed on 
both sides by the first etching (hereinafter referred to as merely "test 
iron plate"). The composition of the present invention was coated on one 
side of the test iron plate, and the state of the dents being filled up 
with the composition was visually evaluated. The size of the test iron 
plate is shown in FIG. 1 and the size of the narrow rectangular dents 
formed on the test iron plate is shown in FIG. 2. 
The results of evaluation were graded by the following criteria. 
.largecircle.: There were no bubbles. 
.DELTA.: There were bubbles in a part of the dents. 
.times.: There were bubbles on the whole surface. 
(2) Surface Smoothness 
The iron plate after evaluated on the dent-filling property was irradiated 
with ultraviolet rays to cure the composition of the present invention, 
and the surface state of the cured film was visually evaluated. 
The results of the evaluation were graded by the following criteria. 
.largecircle.: There were no cissings. 
.DELTA.: There were some cissings. 
.times.: Many cissings were formed. 
(3) Etching Resistance 
The iron plate after evaluated on the surface smoothness was immersed in a 
43% aqueous FeCl.sub.3 solution at 90.degree. C. for 20 minutes, and the 
surface state of the cured film was visually evaluated. 
The results of the evaluation were graded by the following criteria. 
.largecircle.: No change occurred. 
.DELTA.: Coloration occurred. 
.times.: Swelling or exfoliation occurred. 
(4) Alkali Solubility or Peelability 
The iron plate after evaluated on the etching resistance was immersed in a 
20% aqueous NaOH solution at 80.degree. C. for 1 minute, and solubility or 
peelability of the cured film was visually evaluated. 
The results of the evaluation were graded by the following criteria. 
.circleincircle.: The film was completely dissolved and peeled. 
.largecircle.: The film was not completely dissolved, but was peeled. 
.DELTA.: The peeled film partly remained on the metal plate. 
.times.: The film was not peeled. 
(5) Pattern Formability 
The iron plate after evaluated on the alkali solubility or peelability was 
washed with water and dried. Then, a light was applied to the iron plate 
from the back side so as to be able to visually observe by the transmitted 
light the shape of the narrow rectangular holes formed in the iron plate. 
Size of the holes, intervals between the holes, and linearity of the 
longer sides of the rectangles were evaluated depending on the uniformity 
in brightness of the transmitted light. 
The results were graded by the following criteria. 
.circleincircle. Size and intervals of the holes were completely uniform, 
and the longer sides of the rectangles were linear. 
.largecircle.: There was about one defect in about two plates per 100 
plates. 
.DELTA.: There was about one defect in about 3-9 plates per 100 plates. 
.times.: There were one or more defects in 10 or more plates per 100 
plates. 
TABLE 1 
______________________________________ 
Example No. 
1 2 3 
______________________________________ 
Composition 
Component M-5400 70 50 60 
(a) M-5600 0 10 0 
parts 
Component M-315 20 30 20 
(b) 
parts 
Component M-203 0 5 10 
(C1) M-220 10 0 0 
parts M-305 0 5 0 
Component Dodecyl 0 0.5 0 
(C2) mercaptan 
part Mercapto- 0 0 0.5 
propionic 
acid 
Leveling MEGAFACK 0.1 0.1 0 
agent F177 
part NUC SILICONE 0 0 0.2 
L7002 
Mono- ACMO 0 0 10 
functional 
acrylate 
parts 
Photopoly- IRGACURE- 5 0 0 
merization 1700 
initiator RUCILIN TPO 0 5 0 
parts IRGACURE-184 0 0 5 
Viscosity (cps/25.degree. C.) 
2010 2930 1880 
______________________________________ 
The abbreviations in the Table 1 have the following meanings. 
M-5400: ARONIX M-5400; Acryloyloxyethyl monophthalate manufactured by 
Toagosei Co., Ltd. 
M-5600: ARONIX M-5600; Acrylic acid dimer manufactured by Toagosei Co., 
Ltd. 
M-315: ARONIX M-315; Triacrylate of trishydroxyethyl isocyanurate 
manufactured by Toagosei Co., Ltd. 
M-203: ARONIX M-203; Diacrylate of tricyclodecane dimethanol manufactured 
by Toagosei Co., Ltd. 
M-220: ARONIX M-220; Diacrylate of tripropylene glycol manufactured by 
Toagosei Co., Ltd. 
M-305: ARONIX M-305; Triacrylate of pentaerythritol manufactured by 
Toagosei Co., Ltd. 
MEGAFACK F-177: Perfluoroalkyl group-containing oligomer manufactured by 
Dainippon Ink & Chemicals Inc. 
NUC SILICONE L 7002: Silicone polymer manufactured by Nippon Unicar Co., 
Ltd. 
ACMO: Acryloylmorpholine manufactured by Kojin Co., Ltd. 
IRGACURE-1700: Bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine 
oxide manufactured by Ciba Geigy Corp. 
RUCILIN TPO: 2,4,6-Trimethylbenzoyldiphenylphosphine oxide manufactured by 
BASF Corp. 
IRGACURE-184: 1-Hydroxycyclohexylphenyl ketone manufactured by Ciba Geigy 
Corp. 
TABLE 2 
______________________________________ 
Example No. 
1 2 3 
______________________________________ 
Results of Evaluation 
Dent-filling property 
.smallcircle. 
.smallcircle. 
.smallcircle. 
Surface smoothness .smallcircle. .smallcircle. .smallcircle. 
Etching resistance .smallcircle. .smallcircle. .smallcircle. 
Alkali solubility or .smallcircle. .circleincircle. .circleincircle. 
peelability 
Pattern formability .smallcircle. .circleincircle. .circleincircle. 
______________________________________ 
Examples 4-6 
Compositions for back-protecting material curable with active energy rays 
were prepared in the same manner as in Examples 1-3, except that the 
components shown in Table 3 were used. 
Evaluation was conducted on the characteristics of the resulting 
compositions in the same manner as in Examples 1-3. The results are shown 
in Table 4. 
TABLE 3 
______________________________________ 
Example No. 
4 5 6 
______________________________________ 
Composition 
Component M-5400 50 60 60 
(a) M-5600 10 0 0 
parts 
Component M-315 40 30 30 
(b) 
parts 
Component Dodecyl 1 0.5 0 
(C2) mercaptan 
part Mercapto- 0 0 0.5 
propionic 
acid 
Mono- M-5700* 0 10 0 
functional ACMO 0 0 10 
acrylate 
parts 
Leveling MEGAFACK 0.1 0.1 0 
agent F177 
part NUC SILICONE 0 0 0.2 
L7002 
Photopoly- IRGACURE- 5 0 0 
merization 1700 
initiator RUCILIN TPO 0 5 0 
parts IRGACURE-184 0 0 5 
Viscosity (cps/25.degree. C.) 
1790 4060 4210 
______________________________________ 
The abbreviations in Table 3 other than the following have the same 
meanings as in Table 1. 
M-5700: ARONIX M-5700; Acrylic acid adduct of phenyiglycidyl ether 
manufactured by Toagosei Co., Ltd. 
TABLE 4 
______________________________________ 
Example No. 
4 5 6 
______________________________________ 
Results of evaluation 
Dent-filling property 
.smallcircle. 
.smallcircle. 
.smallcircle. 
Surface smoothness .smallcircle. .smallcircle. .smallcircle. 
Etching resistance .smallcircle. .smallcircle. .smallcircle. 
Alkali solubility or .smallcircle. .circleincircle. .circleincircle. 
peelability 
Pattern formability .circleincircle. .circleincircle. .circleincircle. 
______________________________________ 
Comparative Examples 1-4 
Compositions for back-protecting material curable with active energy rays 
were prepared in the same manner as in Examples 1-3, except that the 
components shown in Table 5 were used. 
Evaluation was conducted on the characteristics of the resulting 
compositions in the same manner as in Examples 1-3. The results are shown 
in Table 6. 
TABLE 5 
______________________________________ 
Comparative 
Example No. 
1 2 3 4 
______________________________________ 
Composition 
Compon- M-5400 60 60 70 65 
ent (a) 
parts 
Compon- M-315 0 0 0 15 
ent (b) 
parts 
Compon- M-203 0 0 10 0 
ent (C1) M-220 20 10 0 0 
parts M-305 0 30 0 0 
Compon- Dodecyl 0.5 0 0 0 
ent (C2) mercaptan 
part Mercapto- 0 0 0.5 0 
propionic 
acid 
Leveling MEGAFACK 0.1 0 0 0.1 
agent F177 
part NUC 0 0.2 0 0 
SILI- 
CONE L7002 
Mono- M-5700 20 0 20 0 
functional ACMO 0 0 0 20 
acrylate 
parts 
Photopoly- IRGACURE- 5 0 0 5 
merization 184 
initiator IRGACURE- 0 5 5 0 
parts 651* 
Viscosity (cps/25.degree. C.) 
510 1360 1600 1500 
______________________________________ 
The abbreviations in Table 5 other than the following have the same 
meanings as in Tables 1 and 3. 
IRGACURE-651: Benzylmethyl ketal manufactured by Ciba Geigy Corp. 
TABLE 6 
______________________________________ 
Comparative 
Example No. 
1 2 3 4 
______________________________________ 
Results of evaluation 
Dent-filling property 
.smallcircle. 
.smallcircle. 
X .smallcircle. 
Surface smoothness .smallcircle. .smallcircle. X .smallcircle. 
Etching resistance X .smallcir 
cle. X .smallcircle. 
Alkali solubility or .smallcircle. X .smallcircle. .smallcircle. 
peelability 
Pattern formability X X X X 
______________________________________ 
Comparative Examples 5-7 
Compositions for back-protecting material curable with active energy rays 
were prepared in the same manner as in Examples 1-3, except that the 
components as shown in Table 7 were used. 
Evaluation was conducted on the characteristics of the resulting 
compositions in the same manner as in Examples 1-3. The results are shown 
in Table 8. 
TABLE 7 
______________________________________ 
Comparative 
Example No. 
5 6 7 
______________________________________ 
Composition 
Component M-5400 60 60 60 
(a) 
parts 
Component M-210.sup.a) 40 0 30 
(C1) M-309.sup.b) 0 40 0 
parts 
Component Dodecyl 0.5 0 0 
(C2) mercaptan 
part Mercapto- 0 0 0.5 
propionic 
acid 
Mono- ACMO 0 0 10 
functional 
acrylate 
parts 
Leveling MEGAFACK 0.1 0 0 
agent F177 
part NUC SILICONE 0 0.2 0 
L7002 
Photopoly- IRGACURE- 0 5 0 
merization 1700 
initiator RUCILIN TPO 0 0 5 
parts DALOCURE- 5 0 0 
1173.sup.c) 
Viscosity (cps/25.degree. C.) 
1890 740 2380 
______________________________________ 
The abbreviations in Table 7 other than the following have the same 
meanings as in Tables 1, 3 and 5. 
a) M-210: ARONIX M-210; Diacrylate of adduct of bisphenol A with 4 moles of 
ethylene oxide manufactured by Toagosei Co., Ltd. 
b) M-309: ARONIX M-309; Triacrylate of trimethylolpropane manufactured by 
Toagosei Co., Ltd. 
c) DALOCURE-1173: 2-Hydroxy-2-methyl-1-phenylpropane-1-one manufactured by 
Ciba Geigy Corp. 
TABLE 8 
______________________________________ 
Comparative 
Example No. 
5 6 7 
______________________________________ 
Results of evaluation 
Dent-filling property 
.smallcircle. 
.smallcircle. 
X 
Surface smoothness .smallcircle. .smallcircle. X 
Etching resistance X .smallcircle. X 
Alkali solubility or .smallcircle. X .smallcircle. 
peelability 
Pattern formability X X X 
______________________________________ 
As clear from the above examples, the curable compositions of the present 
invention for back-protecting protecting material used in making shadow 
masks are readily and rapidly cured by irradiation with active energy rays 
or by heating, and the cured film is excellent in all of etching 
resistance, alkali solubility or peelability, and pattern formability even 
when the second etching is carried out at high temperatures. 
Furthermore, since the composition of the present invention does not 
require an organic solvent, a drying oven for evaporation of the organic 
solvent and a recovery device for the solvent are not necessary, there is 
no fear for toxicity of the organic solvent in handling of raw materials, 
and the risks of ignition and explosion at drying can be avoided. 
In addition, curing can be performed in a short time without the drying 
step which causes evaporation of the organic solvent, cost for energy can 
be reduced and fire can be prevented, and the existing steps can be 
utilized to attain improvement. In these respects, the present composition 
is useful, and is markedly high in industrial value.