JPH0219848A - Photosensitive resin composition - Google Patents

Abstract

PURPOSE:To improve the water developing, the water resisting and the screen adhesive properties of the title composition by incorporating an inner cross- linking type acrylic resin emulsion in the component of the resin composition as a synthetic resin emulsion using especially PVA as an emulsifier. CONSTITUTION:The resin composition is mainly composed of three components comprising the aqueous emulsion of an inner crosslinking type acrylic resin which has >=65wt.% of a trichlene insoluble matter, and is obtd. by subjecting an acrylic monomer and a monomer having two or more of polymerizable unsatd. groups to an emulsion polymerization in the presence of polyvinyl alcohol (PVA) having a degree of polymerization of <=1,500, the polyvinyl alcohol and/or its derivative and a photosensitive agent. And, the monomer having two or more of the polymerizable unsatd. groups is composed of the monomer having two or more of allyl groups. Thus, the characteristics such as the water developing, the water resisting and the screen adhesive properties of the resin composition are sufficiently satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a photosensitive resin composition used as a photosensitive emulsion for screen plate making.

(Prior art) Screen printing is a type of stencil printing, and is a printing method in which a resist film is formed on a screen using a photographic method, and ink is extruded through the screen using a squeegee (a spatula-shaped tool made of polyurethane rubber). be.

Many things printed by screen printing can be found around us. Examples include the printing of letters and numbers on clock dials, the front of stereos and televisions, patterns on ceramics, and printing on bottles.

In the electronics industry, which has been growing rapidly in recent years, screen printing is used to manufacture printed circuit boards on which LSIs are mounted, touch panel switches for computer word processors, flexible circuit boards, etc. Screen printing used in these fields naturally requires strict accuracy down to the micron level, and the printing plate, which is one of the elements that make up screen printing, also requires a sophisticated plate system. .

The fibers used for screens are limited to some extent, and the following four types
Types of fibers are mainly used.

1) Tetron fiber 2) Nylon fiber 3) Stainless steel fiber 4) To form a resist film on the silk screen, ■direct method,
■Indirect method, ■Direct method, ■Direct film method.

(2) A baguette (shaped like a stainless steel rain gutter) containing a liquid photosensitive emulsion with a direct viscosity of about 4,000 to 8.0 OOcP is used to coat the screen with the photosensitive emulsion. When a predetermined thickness is achieved by repeating coating and drying, a resist film is formed on the screen by exposing to ultraviolet light and developing with water.

■Indirect method A photosensitive emulsion film (main component is gelatin) is formed in advance on the polyester film, and after exposing it to ultraviolet rays, it is hardened with hydrogen peroxide and developed with hot water. , press it onto the screen with a rubber roller to adhere it.

When the polyester film is peeled off after drying, the image remains on the screen, which becomes a resist film.

■It has two layers: a direct process polyester film and an unsensitized emulsion film (mainly polyvinyl alcohol), and this unsensitized film is bonded to the screen using a liquid emulsion mixed with dichromate. The acid salt penetrates and diffuses into the unsensitized film during drying, sensitizing the unsensitized emulsion film.

After drying, the polyester film is peeled off and exposed and developed to form a resist film on the screen.

The use of diazo photosensitizers instead of dichromates is impractical because the molecular weight of diazo photosensitizers is much larger than that of dichromates, and the rate of permeation and diffusion is slow.

■Direct film method A photosensitive emulsion film is coated on a polyester film. The difference from direct film is that the emulsion film on the polyester film is photosensitive. This difference is a major advantage of the direct film method, and it is a new method that became possible for the first time based on research to improve photosensitizers and advances in manufacturing technology.

Since the emulsion film is already sensitized, it can now be attached to the screen using just water.

The basic composition of the photosensitive emulsion for film, which is a direct film method screen plate making material, is as follows: Polyvinyl alcohol Polyvinyl acetate Emulsion Diazo sensitizer Other additives Dyes 40-60 N 60-40 3-6 Small amount I Polyvinyl alcohol (hereinafter referred to as PVA) works as a photocurable photosensitive resin in combination with a diazo photosensitive agent, and polyvinyl acetate (hereinafter referred to as PVAc) emulsion is used to improve detail resolution and water resistance. Added as a purpose. Although emulsions other than PVAc emulsions may be considered, PVAc emulsions are generally most commonly used due to their miscibility with PVA or diazo photosensitizers.

However, depending on the blending ratio of PV, A and PVAc emulsion, the water developability, precision, and
The drawback was that water resistance, solvent resistance, and screen adhesion were largely affected.

In other words, water developability is a property necessary for development in which a positive film is overlaid on a photosensitive resin layer and exposed to light, and the unexposed areas are dissolved and removed with water. PVA alone is better, and PVAc emulsion is better in the amount used. When the amount increases, water developability deteriorates.

Accuracy is whether the printing plate can be changed faithfully to the positive film, and this is one of the purposes for which PVAc emulsions are blended in the past, but some of the exposed areas may be dissolved or removed by water development, or unexposed areas may be dissolved or removed. If resin remains, accuracy will decrease.

Accuracy is poor with PVA alone and improved by increasing the PVAc emulsion.

Water resistance is 1f in the exposed area! After exposure, the exposed plate is immersed in water at 15-25°C for 2-3 minutes to dissolve some of the unexposed areas, and then the plate is taken out and sprayed with water at a water pressure of 5-3 kg/d. Water resistance is an important property because it is developed with PVA, but PVA alone has poor water resistance even if the exposed area is water-insoluble;
Emulsion blend increases water resistance.

However, even blends of PVAc emulsions do not have sufficient water resistance.

Solvent resistance is necessary because used printing plates are cleaned with solvent.

For blends of PVAc emulsions, increasing solvent resistance becomes worse.

Although it is said that PVA alone has better solvent resistance, it is not sufficient.

Screen adhesion is the adhesion between the screen and the exposed resin, and if the adhesion is weak, it will not be possible to increase the number of printings; it must be able to withstand more than 1,000 printings.

PVA alone is poor, and a blend of PVAc emulsion improves screen adhesion.

In this way, there is no point in the blending ratio of PVA and PVAc emulsion that satisfies all of them 100%, and the key is to find the blending ratio that is the greatest common divisor. In particular, since the photosensitive direct film is basically applied to a screen with water, it is necessary to consider the blending ratio so that it exhibits good water solubility.

(Problems to be Solved by the Invention) The performance of photosensitive emulsifiers has traditionally been based on the balance of the combination of PVA and PVAc emulsions. The performance was also not fully satisfactory. Therefore, the problem to be solved by the present invention is to provide a photosensitive resin composition that fully satisfies the above-mentioned properties as a photosensitive emulsion for screen printing, particularly for direct printing and direct film printing.

(Means for solving the problem) If other emulsions, such as acrylic emulsions, are used instead of the PVAc emulsion blended with PVA, the miscibility with PVA and diazo photosensitizers is poor as described above. However, the inventor thought that this may be due to the fact that surfactants are usually used as emulsifiers in acrylic emulsions, and carried out emulsion polymerization using a specific PVA as an emulsifier together with a crosslinking monomer. The present invention was completed by finding a solution to the problem by using an acrylic emulsion with a specific degree of crosslinking.

That is, the present invention is a photosensitive resin composition containing the following three components (A) to (C) as main ingredients.

<A) A trichlene insoluble content of 65% by weight or more obtained by emulsion polymerization of an acrylic monomer and a monomer having two or more polymerizable unsaturated groups in the presence of polyvinyl alcohol with a degree of polymerization of 1,500 or less Aqueous emulsion of internally crosslinked acrylic resin.

(B) Polyvinyl alcohol and/or its derivatives.

(C) Photosensitizer.

And, the monomer having two or more polymerizable unsaturated groups has two or more allyl groups.
The photosensitive resin composition according to claim 1, which is a monomer having the above.

Although it is extremely difficult to produce an aqueous emulsion of an internally crosslinked acrylic resin using PVA as an emulsifier, which is used in the present invention as shown in Structure (A), it can be achieved by the following method.

When a PVA oligomer with a degree of polymerization of 50 or less is used as an emulsifier, it is possible to emulsion copolymerize an acrylic monomer and a polyfunctional monomer with the usual amount of about 10% of the total monomers. can.

When the degree of polymerization of PVA increases, it is necessary to use a small amount of surfactant or a chain transfer agent such as alcohols, monoaldehydes, or chlorinated hydrocarbons in the case of normal usage. emulsion copolymerization can be carried out by

In this case, if the amount of PVA used is the same as or more than the total amount of monomers, emulsion copolymerization can be carried out even with PVA alone.

However, in both cases, the degree of polymerization of PVA is 150.
Must not exceed 0.

Therefore, as the PVA for emulsifier used in the present invention, PV with a degree of polymerization of 1500 or less and a degree of saponification of 60 to 99 mol% is recommended.
A is used. In particular, those having a degree of polymerization of 300 to 1000 are suitable.

Modified PVA described below as a PVA derivative can also be used as long as the degree of polymerization is 1500 or less.

It is particularly important to limit the degree of polymerization to 1500 or less;
If only PVA exceeding 500 is used, an internally crosslinked acrylic resin emulsion cannot be obtained.

The amount used is preferably 5 to 200% by weight based on the total monomers.

Examples of the acrylic single X substance used in the present invention include:
Methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, +30-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (Meth) of nonyl (meth)acrylate, lauryl (meth)acrylate, etc.
Examples include alkyl esters of acrylic acid having 1 to 12 carbon atoms.

Copolymerizable monomer i at 50% by weight or less based on the acrylic monomer
Copolymerizable monomers that may be used in combination include styrene, methylstyrene, vinyltoluene, vinyl chloride, ethylene, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl versatate, and acrylic monomers. A monofunctional monomer may also be used in an amount of 10% by weight or less. Examples of the monofunctional monomer include (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, or amides of these acids, vinyl sulfonate, and N-methylol (meth)acrylamide.

Examples of the polyfunctional monomer having two or more polymerizable unsaturated groups used in the present invention include divinyl compounds, di(meth)acrylate compounds, tri(meth)acrylate compounds, tetra(meth)acrylate compounds, diallyl compounds, Monomers having two or more polymerizable unsaturated groups such as triallyl compounds and tetraallyl compounds, more specifically, for example,
Divinylbenzene, divinyl adipate, ethylene glycol di(meth)acrylate, 1,3-butyl di(meth)acrylate, triethylene glycol di(meth)acrylate
Examples include acrylate, trimethylolpropane tri(meth)acrylate, diallyl phthalate, triallyl cyanurate, and tetraallyloxyethane.

From the viewpoint of copolymerizability and crosslinking effect, monomers having two or more allyl groups, such as triallyl isocyanurate (TAIC) and tetraallyloxyethane (TAB), are preferred.

The amount of the polyfunctional monomer used is preferably 0.1 to 10.0 parts by weight per 100 parts by weight of the acrylic monomer.

The trichlene-insoluble portion of the internally crosslinked acrylic resin as used in the present invention is represented by the following formula.

Trichlene insoluble fraction (weight %) Weight before Trichlene extraction - PVA content (calculated value) x
100 The calculated value is the amount of P contained in the resin based on the amount of PVA used.
This is a value obtained by calculating the proportion of VA and calculating the content of PVA contained in the weight before extraction with trichlene.

PVA or its derivative shown in configuration (B) can be used as a photocurable photosensitive resin composition in combination with a photocrosslinking agent, but it can be used in a wider range than PVA used as an emulsifier in configuration (A). can be used.

Therefore, the degree of polymerization is 300-4000 and the degree of saponification is 60-9.
A range of 9 mol % of PVA or its derivatives is used.

It goes without saying that the PVA used as an emulsifier in composition (A) also exhibits a photocuring effect. Examples of PVA derivatives include olefin copolymerized modified products of PVA, vinyl carboxylic acid copolymerized modified products, and alkyl vinyl ether copolymerized products. modified products, (meth)acrylate copolymerized modified products, acrylamide copolymer modified products, carboxylic acid monomer copolymerized modified products, sulfonic acid monomer copolymerized modified products,
Modified P such as allyl alcohol copolymerized modified product, cationized modified product, etherified modified product, esterified modified product, acetalized modified product, acetoacetylated modified product, ethylene oxide addition modified product, propylene oxide addition modified product, etc.
VA is appropriate.

As the photosensitizer shown in configuration (C), any photosensitizer that is already known as a photosensitizer for photosensitive emulsions can be used.

Typical examples include water-soluble diazo resins made by polycondensing diazo compounds such as dichromates and diphenylamines with aldehydes; agent is used.

The amount of photosensitive agent used is preferably in the range of 2 to 20 parts by weight per 100 parts by weight of the PVA or its derivative.

If it is less than 2 parts by weight, sufficient photocrosslinking cannot be achieved, and if it is used in excess of 20 parts by weight, the storage stability of the photosensitive resin composition cannot be obtained.

Although the photosensitive resin composition of the present invention has the above-mentioned components as its main ingredients, it can optionally contain additives that are commonly used in photosensitive compositions.

Examples of such optional additives include emulsion stabilizers, PTL adjusters, plasticizers, wetting agents, antifoaming agents, and colorants such as dyes and pigments.

To produce the photosensitive resin composition of the present invention, the internally crosslinked acrylic resin emulsion (A) and the aqueous solution of PVA or its derivative (B) are mixed, and other components are added as necessary. The photosensitive resin composition of the present invention is obtained by stirring and mixing, and finally adding and mixing the photosensitive agent aqueous solution (C).

It is not only the PVA or its derivative (B) that reacts with the photosensitizer, but also the PVA emulsifier contained in the internally crosslinked acrylic resin emulsion.

Therefore, an internally crosslinked acrylic resin emulsion;
The blending ratio with PVA or its derivatives is preferably 10
~60 (wt%) is suitable.

Incidentally, total PVA: the sum of the weights of PVA as an emulsifier in the internally crosslinked acrylic resin emulsion (A) and (Bl) PVA or its derivative.

Total resin content = the sum of the weight of the resin content and all PVA in the internally crosslinked acrylic resin emulsion (A).

(Effects) The photosensitive resin composition of the present invention uses an internally cross-linked acrylic resin emulsion with PVA as an emulsifier as a synthetic resin emulsion as a component. It has the effect of being extremely excellent in all of the various performances as a transparent emulsion, such as water developability, precision, water resistance, solvent resistance, and screen adhesion.

The photosensitive resin composition of the present invention is not only useful as a photosensitive emulsion for screen plate making, but also can be used for letterpress printing plates, name plates, molds, etc. by leaving a photosensitive part of the photosensitive resin composition as a relief. It can also be used for resin molds for printing, resin molds for embossing, etc.

(Example) Next, the present invention will be explained with reference to Examples and the Hiei test.

Example 1 A solution having the following composition was prepared in a 500 ml four-bottle flask equipped with a thermometer, stirrer, reflux condenser, and dropping funnel, and the solution was purged with nitrogen for about 15 minutes.

PVA (degree of saponification 88 mol%, 20!!: Average degree of polymerization per unit 500) Ethanol 18n Deionized water 156 Prepare a mixed monomer solution with the following composition in a separate container, and purify with nitrogen for about 15 minutes. went.

Methyl methacrylate 40 parts by weight Butyl acrylate 5Qn Acrylonitrile
10II acrylic acid
2 u Tetraallyloxyethane (TAB) 1 17 Next, the internal temperature of the reaction vessel was heated to 60°C, 10 parts by weight of the mixed monomer solution prepared earlier was added, and ljl parts of a 10% aqueous hydrogen peroxide solution was added. Then, 1 part by weight of 10% mono-ascorbic acid was added to carry out initial polymerization. Then, the remaining mixed monomer solution was added dropwise over 3 hours. 10% during that time
4 parts by weight of an aqueous hydrogen peroxide solution and 4 parts by weight of a 10% L-ascorbic acid aqueous solution were added in portions during and after the dropwise addition. After the completion of the dropwise addition, the internal temperature was maintained at 60 to 70°C for an additional hour to allow the polymerization reaction to proceed. After completion, it was cooled.

The enriched polymer solution has no coagulum and has a solid content concentration of 40% by weight.
It was a stable emulsion with good fluidity and a viscosity of 20,000 P. This emulsion was diluted with deionized water to a solid concentration of 20%, poured onto a polyester film, and left to stand in a thermostat at 40°C for 10 hours until the thickness was approximately 0.2%.
A film was prepared and cut into squares of 4 Qll x 4 am to serve as samples for the solvent resistance test. The sample was placed in a thimble and subjected to trichlene extraction using a Soxhlet extractor for 5 hours. As a result of the test, the triclene extraction rate was 10% by weight.

Next, Gohsenol GH-17 (partially saponified PVA with a degree of polymerization of 1700 and a degree of saponification of 88 mol%/Nippon Synthetic Chemical Industry ■
150r (registered trademark) was dissolved in 850sr of water, and the polyacrylic acid ester copolymer emulsion obtained above (
900 g (solid content: 40%) were added and mixed, and 150 g of a 10% aqueous solution of diazo resin was mixed thereto to prepare a photosensitive liquid. This solution was applied using a packet to a 225 mesh monofilament polyester screen stretched over an aluminum frame. Application and 30-40°C.

The hot air drying process was repeated 3 to 4 times to obtain a photosensitive film with a thickness of 90 μm (including the thickness of the screen). A positive film for printed wiring was vacuum-adhered to the photosensitive film of this screen photosensitive plate, and the 0th order image was exposed for 2 minutes from a distance of 1 m using a 4K14 high-pressure mercury lamp, and the 0th order image was developed (washed with water) to remove the remaining photosensitive film in the image area. Completely removed.

Next, the developed plate was dried (at 45°C) to prepare a plate for printed circuit boards. This plate has excellent water and solvent resistance, and has a swelling degree of 20% after 24-hour immersion in water and organic solvents compared to diazo-based plates using polyvinyl acetate.
~50% less.

When 5,000 sheets were printed using this plate, there was no damage to the image, and printing could be performed without any change in printing reproducibility from beginning to end.

Example 2 In the same manner as in Example 1, a solution having the following composition was prepared in a four-bottle flask having a content of i 500 + m, and the flask was purged with nitrogen for about 15 minutes.

PVA (degree of saponification 88%, 10 parts by weight average degree of polymerization 1400) Methanol 1 on bromotrichloromethane 0.5 deionized water
A mixed monomer solution having the following composition was prepared in a separate 150 liter container, and the mixture was purged with nitrogen for about 15 minutes.

Methyl methacrylate 42 parts by weight Butyl acrylate 45 N acrylonitrile 51 N 2-droxy methacrylate 3 N methacrylic acid
2I nottrialyl isocyanurate (TAIC) 1 ,
571 Next, the internal temperature of the reaction vessel was heated to 60°C, 10 parts by weight of the mixed monomer solution prepared earlier was added, 1 part by weight of a 10% aqueous hydrogen peroxide solution, and 1 part by weight of 10% L-ascorbic acid. Initial polymerization was carried out by adding 100% of the above amount. Then, the remaining mixed monomer solution was added dropwise over 3 hours. During that time, 4 parts by weight of a 10% aqueous hydrogen peroxide solution and 4 parts by weight of a 10% aqueous ascorbic acid solution were added in portions during and after the dropwise addition.
The temperature was maintained at ~70°C to complete the polymerization reaction, and then the mixture was cooled.

The obtained polymerization liquid had no coagulum and had a solid content concentration of 40% by weight.
It was a stable emulsion with a viscosity of 30.000 cP.

Trichlene extraction was performed using the same test method as in Example 1, and as a result, the trichlene extraction rate was 3FEJi%.

Next, 150 g of Gohsenol GH-17 was dissolved in 850 g of water, 900 g of the polyacrylate copolymer emulsion (solid content 40%) obtained above was added and mixed, and 150 g of a 10% diazo resin aqueous solution was mixed therewith. A photosensitive solution was prepared. This solution was applied onto a polyester film to form a photosensitive emulsion film layer. A screen was adhered to this and after drying, the polyester film was peeled off to obtain a screen photosensitive plate.

An image of printed wiring was exposed and developed on the photosensitive film of this screen photosensitive plate in the same manner as in Example 1 to form a resist film on the screen to prepare a plate for a printed circuit board.

This screen plate has excellent water and solvent resistance, and as a result of printing, it was confirmed that this screen plate was able to resolve fine lines and there were no abnormalities in the plate even after printing, indicating that it has excellent printing durability and resolution. Ta.

Example 3 A solution having the following composition was prepared in a 500 ml four-bottle flask in the same manner as in Example 1, and the solution was purged with nitrogen for about 15 minutes.

PVA (degree of saponification 88%, 15 parts by weight average degree of polymerization 500) Ethanol 1811 theory ionized water 46 In a separate container, put the following (
A), an aqueous solution of PVA (degree of saponification 88%, degree of polymerization 500), and (B) a mixed monomer solution were prepared, and each solution was replaced with nitrogen for about 15 minutes.

(A) PVA (degree of saponification 88%, 10 parts by weight Average degree of polymerization 500) Deionized water 90 parts by weight (B) Methyl methacrylate 37 parts by weight 2 Ethylhexyl acrylate 45 parts ! Acrylamide 3 methacrylic acid
2n tetraallyloxyethane
2 Next, heat the internal temperature of the reaction container to 75°C, add 10 parts by weight of the mixed monomer solution (B) prepared earlier, and
Initial polymerization was carried out by adding 2 parts by weight of 0% ammonium persulfate aqueous solution.

Next, the PVA aqueous solution (A) and the remaining mixed monomer solution (
B) were added dropwise simultaneously over 3 hours. During this time, 4 parts by weight of a 10% ammonium persulfate aqueous solution was added in portions during and after the dropwise addition. After the addition was completed, the internal temperature was maintained at 75 to 80° C. for another hour to complete the polymerization reaction, and then cooled.

The obtained polymerization liquid had no coagulum and had a solid content concentration of 42% by weight.
It was a very fluid and stable emulsion with a viscosity of 000cP. The trichlene extraction rate of the film of this emulsion was 5% by weight.

Next, a photosensitive film was obtained using the same formulation and operation as in Example 1 to prepare a plate for a printed circuit board.

This plate has excellent water resistance and solvent resistance, and as a result of printing, there was no image damage even after printing 5000 sheets, and the printing reproducibility was excellent throughout.

Comparative Example 1 in which the internally crosslinked acrylic resin emulsion used in Comparative Test Example 1 was changed as follows.
5 and Comparative Example 6 using only an aqueous solution of PVA alone, printed circuit board boards were created in the same manner as in Example 1, and various performances were tested. The results were as shown in Table 1.

Comparative Example 1: Internally crosslinkable acrylic resin emulsion using a surfactant as an emulsifier.

n PV with 2H polymerization degree of 1000 and saponification degree of 88 mol%
Acrylic resin emulsion (non-crosslinked) using A as an emulsifier.

PVAc emulsion (contains plasticizer) using Nol 3+PVA as an emulsifier.

4: Same (without plasticizer).

175: Internally crosslinked PVAc emulsion (with plasticizer) using a surfactant as an emulsifier.

#6: Example using only PVA aqueous solution.

1st surface water developability ○; Badly exposed screen photosensitive plate was immersed in water and further water was sprayed with a spray gun to easily develop the plate in water.

X: Resin remained in unexposed areas and water development could not be performed.

Accuracy 07 It reproduced even a thin line with a width of about 60 μl and had excellent edge sharpness.

Δ: Edge sharpness was not sufficient.

×: A thin line with a width of about 60 μl could not be reproduced.

A printed circuit board plate was immersed in a mixed solution of waterproof water and propylene alcohol (weight ratio 1:1) for 24 hours, and the swelling ratio was determined.

The O1 loading rate was 50% by weight or less.

x: Swelling rate was 60% by weight or more.

A printed circuit board plate was immersed in solvent-resistant trichlene for 24 hours, and the swelling ratio was determined.

○: Swelling rate was 20% by weight or less.

Δ: Swelling rate was 21 to 50% by weight.

×; Swelling rate was 51ffi% or more.

Press commercially available cellophane 1 onto the surface of a screen-adhesive printed circuit board plate, peel it off, and observe.

○: No abnormality was observed.

A part of the photosensitive resin of the plate for the niblint substrate adhered to the cellophane tape and peeled off from the plate.

Claims (1)

[Claims] 1. A photosensitive resin composition containing the following three components as main ingredients. (A) The trichlene insoluble content is 65% by weight or more, obtained by emulsion polymerization of an acrylic monomer and a monomer having two or more polymerizable unsaturated groups in the presence of polyvinyl alcohol with a degree of polymerization of 1,500 or less. Aqueous emulsion of internally crosslinked acrylic resin. (B) Polyvinyl alcohol and/or its derivatives. (C) Photosensitizer. 2. The photosensitive resin composition according to claim 1, wherein the monomer having two or more polymerizable unsaturated groups is a monomer having two or more allyl groups.