JPS6118736B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel photopolymerizable composition that is developable only with water.

Conventional photopolymerizable compositions have better strength and chemical resistance after curing than other photosensitive materials, and are therefore widely used in printing plates, resists, and the like. However, these products require the use of a solvent or an alkaline solution containing a solvent during development, which creates a poor working environment such as workers inhaling solvent vapor and odor in the workplace. Moreover, in the case of using a flammable solvent, there is a risk of ignition, and when the developer waste solution contains a high concentration of organic matter, a treatment device is required.

In addition, in developing methods that use organic solvents or alkaline solvents, the resin swells and is forcibly removed by brushing, which impairs resolution and printing durability. Another drawback is that the surface of the base zinc or aluminum is corroded, making it non-uniform. On the other hand, some photopolymerizable compositions that can be developed only with water have also been proposed. This photopolymerizable composition consists of a water-soluble polymer, a photopolymerizable ethylenically unsaturated compound, and a photopolymerization initiator, and simultaneously photopolymerizes the ethylenically unsaturated compound to form a polymer. Curing is performed by enveloping water-soluble polymers in the tissue.

However, lithographic printing plates obtained using this type of photopolymerizable composition have poor ink transfer properties at the start of printing, resulting in an increase in the number of defective prints and an increase in waste paper. This has drawbacks such as difficulty in obtaining practically sufficient printing durability, probably because the water-soluble polymer dissolves out. Therefore, as a result of studies to eliminate these drawbacks, we found that in a photopolymerizable composition consisting of a polymer, a crosslinking agent, and a photopolymerization initiator, ethylenically unsaturated groups and water-soluble salt groups were added to the side chains of the polymer. By introducing this, even if the photosensitive liquid itself is a solvent type, it is possible to create a printing plate that can be developed with only water after application and drying, and has good ink transfer properties and printing resistance. It has been found that a photopolymerizable composition can be obtained. The present invention has been made based on this knowledge.

That is, the photopolymerizable composition of the present invention comprises (a) a polymer having an ethylenically unsaturated group and a water-soluble salt group in its side chain; and (b) a photopolymerizable unsaturated polymer containing an ethylenically unsaturated group. It consists of three essential components: a compound and (iii) a photopolymerization initiator, and if necessary, a thermal polymerization inhibitor to improve the storage stability of the composition.
It contains various fillers and plasticizers to improve mechanical strength, solvent resistance, and adhesion to the support after photopolymerization. Among these, the polymer having an ethylenically unsaturated group and a water-soluble salt group in the side chain used in the present invention refers to a polymer containing 5% by weight or more of an unsaturated carboxylic acid as a constituent unit (hereinafter referred to as "base polymer"). ) is added with 0.03 to 0.85 equivalents of an oxysilane ring-containing ethylenically unsaturated compound to the carboxyl group, and 0.60 to 1.00 equivalents of the remaining carboxyl group is neutralized to form an alkali metal salt or ammonium salt. be.

Until now, photopolymerizable compositions are known in which an oxysilane ring-containing ethylenically unsaturated compound is added to a polymer containing a carboxyl group, and the photopolymerizable composition is mainly composed of a polymer containing an ethylenically unsaturated group and a carboxyl group in the side chain. It is being (For example, JP-A-47-30402, JP-A-47-31704, JP-A-49-34041)
(See Special Publication No. 49-17874).

However, since this type of polymer contains only a carboxyl group as an ionizable group in its molecule, it cannot be developed with water alone, although it is soluble in an alkaline aqueous solution.

On the other hand, the polymer of the present invention having an ethylenically unsaturated group and a water-soluble salt group in its side chain is soluble only in water, and since it has an unsaturated group, it cannot be easily exposed to light. It is photopolymerized together with a photopolymerizable ethylenically unsaturated compound, completely reacting and curing, and becoming insolubilized.
Therefore, when used in a lithographic printing plate, it can be developed with only water without using an alkaline aqueous solution during development, and the cured area exposed and developed has extremely water-repellent and lipophilic properties. This product has the advantage of greatly reducing waste paper at the start of printing, and compared to the conventional polymer-enveloped type in which only the ethylenically unsaturated compound reacts and envelops the polymer, it Since not only the saturated compound but also the unsaturated groups of the polymer itself participate in the reaction, a very strong image is formed and printing durability is improved.

On the other hand, when used as a resist, since the developer does not contain a solvent, there is an advantage that swelling of the resin in the hardened portion during development is less likely to occur, resulting in good resolution and chemical resistance. Furthermore, since development can be performed using ordinary water (tap water), workability and working environment can be maintained favorably, and waste liquid treatment is also easy.

The base polymer used for preparing the composition of the present invention needs to contain unsaturated carboxylic acid as a constituent unit of at least 5% by weight of the total constituent units, and usually contains 5 to 70% by weight. is desirable. When the amount of unsaturated carboxylic acid units is less than 5% by weight, sufficient ethylenically unsaturated groups and water-soluble salt groups cannot be introduced to provide sufficient photopolymerizability and water solubility. On the other hand, it is often preferable to keep the unsaturated carboxylic acid unit at 70% by weight or less in terms of the polar glass transition temperature of the base polymer. In particular, when high printing durability is required as a lithographic printing plate, at least one constituent unit selected from styrene compounds, unsaturated nitriles, unsaturated carboxylic acid esters, and fatty acid vinyl esters is used as the constituent unit of the base polymer. It is preferred that the ethylenically unsaturated compound be contained in an amount of 95 to 30% by weight of the total structural units. By adding such a structural unit, desirable properties can be obtained as a lithographic photosensitive layer or a resist.

The unsaturated carboxylic acids used in the base polymer of the present invention include acrylic acid, methacrylic acid,
Itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetic acid, α-ethyl acrylic acid, angelic acid; monomethyl ester, monoethyl ester, monopropyl ester, monoisopropyl ester, mononormal of itaconic acid, maleic acid or fumaric acid Examples include butyl ester, maleic anhydride, itaconic anhydride, and the like, and these can be used alone or in combination. Styrene compounds include styrene, α-methylstyrene, vinyltoluene, etc.
Examples of unsaturated nitriles include acrylonitrile and methacrylonitrile; examples of unsaturated carboxylic esters include alkyl acrylates and alkyl methacrylates, such as methyl acrylate, ethyl acrylate, normal propyl acrylate, isopropyl acrylate,
Examples of fatty acid vinyl esters include octyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, and lauryl methacrylate, and vinyl acetate and vinyl propionate. These can be used alone or in combination.

The base polymer is prepared by polymerizing an unsaturated carboxylic acid, or a mixture of a styrene compound, an unsaturated nitrile, an unsaturated carboxylic acid ester, a fatty acid vinyl ester, etc. using a conventional method such as solution polymerization, emulsion polymerization, or suspension polymerization. Manufactured by polymerization. In this polymerization reaction, peroxides, azo compounds, etc. can be used as a polymerization initiator, but in consideration of the storage stability of the photopolymerizable composition, it is recommended to use a polymerization initiator with as high decomposition efficiency as possible. is preferred. As the polymerization solvent, ketones, esters, alcohols, ethers, aromatic hydrocarbons, etc. can be used, but due to the reaction stability during the addition reaction of the oxirane ring-containing ethylenic saturated compound, alcohol-based solvents are preferred. In particular, alcohols having 3 to 5 carbon atoms are preferred.

A polymer having an ethylenically unsaturated group and a water-soluble salt group in its side chain can be obtained by an addition reaction of an oxirane ring-containing ethylenically unsaturated compound to a carboxyl group of a base polymer and a neutralization reaction with an alkali.

Ketones, esters, alcohols, ethers, aromatic hydrocarbons, etc. can be used as reaction solvents during the addition reaction, but from the viewpoint of reaction stability, alcoholic solvents, especially those with 3 carbon atoms, are preferred.
-5 alcohols or a mixed solvent of these alcohols and other organic solvents are preferred. Further, as the reaction catalyst, any catalyst for the reaction between a carboxylic acid and an oxirane ring compound can be used, but trimethylbenzylammonium sideroxide is particularly effective. In carrying out this reaction, it is necessary to have a reducing substance present as a polymerization inhibitor in the reaction system in order to suppress vinyl type addition polymerization of the oxirane ring-containing ethylenically unsaturated compound. Hydroquinone is effective as such a compound.

Examples of oxirane ring-containing ethylenically unsaturated compounds include glycidyl acrylate, glycidyl methacrylate, acrylic glycidyl ether, α-
Ethyl glycidyl acrylate, crotonyl glycidyl ether, glycidyl crotonate, glycidyl isocrotonate, itaconic acid monoalkyl ester monoglycidyl ester, fumaric acid monoalkyl ester monoglycidyl ester,
Examples include monoalkyl maleate monoglycidyl ester, but glycidyl acrylate and glycidyl methacrylate are more preferred in terms of reactivity. In view of the photosensitive speed, adhesion to the substrate, developability and toughness of the film of the resulting photopolymerizable composition, the amount is preferably 0.03 to 0.85 equivalents, particularly preferably, based on the carboxyl group of the base polymer.
0.10 to 0.80 equivalents of oxirane ring-containing ethylenically unsaturated compound are added.

After completing the addition reaction of the oxirane ring-containing ethylenically unsaturated compound to the carboxyl group of the base polymer in this manner, the remaining carboxyl group is neutralized with an alkali to form an alkali metal salt or an ammonium salt. Examples of the alkali used include alkali metal compounds such as sodium hydroxide and potassium hydroxide, ammonia, and amines such as ethanolamine, triethanolamine, and trimethylamine. Neutralization can be achieved by adding these aqueous or alcoholic solutions to the base polymer solution after the completion of the addition reaction. In this case, it is necessary to neutralize 0.60 to 1.00 equivalents of carboxyl groups remaining after the addition reaction due to water developability. If the degree of neutralization is less than 0.60 equivalent, development using only water becomes difficult.

The photopolymerizable composition containing an ethylenically unsaturated group used as the component (b) includes acrylic acid, methacrylic acid, or an ester thereof, such as methyl, ethyl, n-propyl, isopropyl, n-hexyl, n-octyl. , n-dodecyl, cyclohexyl, tetrahydrofurfuryl, allyl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 3chloro-2-hydroxy or 4-hydroxybutyl acrylates and methacrylates,
Or mono- or diacrylates and mono- or dimethacrylates of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, butylene glycol, or trimethylolpropane triacrylate and methacrylate, pentaerythritate tetraacrylate and methacrylate, etc. , acrylamide, methacrylamide or derivatives thereof, such as N-methylolacrylamide and methacrylamide, N-methoxyacrylamide and methacrylamide, N,N'-methylenebisacrylamide and methacrylamide, N,N'-hexamethylenebisacrylamide and methacrylamide. amide, styrene, vinyltoluene, divinylbenzene, diallyl phthalate, triallyl cyanurate, vinyl acetate, etc. Particularly preferred are trimethylolpropane triacrylate and methacrylate having 3 to 4 ethylene groups, and trimethylol. Ethane triacrylate and methacrylate, tetramethylolmethane triacrylate and methacrylate, pentaerythritate tetraacrylate and methacrylate.

The photopolymerization initiator of component (iii) is a commonly used photopolymerization initiator. Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin-n-propyl ether, benzoin isopropyl ether, benzoin-n-butyl ether,
Benzoin isobutyl ether, benzoin-
Sec-butyl ether, benzoin phenyl ether, α-methylbenzoin, α-ethylbenzoin, α-methylbenzoin methyl ether, α
-phenylbenzoin, α-methylolbenzoin, α-methylolbenzoin ethyl ether,
α-allyl benzoin, benzoin trimethylsilyl ether, γ-hydroxy-γ-phenyl-
Benzoin derivatives such as γ-benzoylbutyric acid, benzophenone, 3-methylbenzophenone, 2,
4'-dimethylbenzophenone, 2,2'-dimethyl-3-oxybenzophenone, 2-nitrobenzophenone, 4-aminobenzophenone, 4-acetylbenzophenone, 2-chlorobenzophenone, Benzophenone derivatives such as 2,4'-dichlorobenzophenone, 4-benzoylbenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, anthraquinone, β- Methyl anthraquinone, β-ethylanthraquinone, β-chloroanthraquinone, 1,2-benzoanthraquinone,
Examples include quinone derivatives such as phenanthrenequinone, and diacetyl, benzyl, diphenyl disulfide, β-naphthalenesulfonyl chloride, acetophenone, ω-bromoacetophenone, and the like.

The above photopolymerization initiators can be used alone or in combination of two or more. Preferred compounds for obtaining relatively fast sensitivity are β-ethyl anthraquinone, benzophenone, and 4,4'-
Bis(dimethylamino)benzophenone alone,
Or a combination.

A photopolymerizable ethylenically unsaturated compound is a polymer having an ethylenically unsaturated group and a water-soluble salt group in its side chain.
It is preferably used in an amount of 1 to 100 parts by weight per 100 parts by weight. The photopolymerization initiator is used in an amount of 0.001 to 10% by weight based on the total weight of the photopolymerizable composition.

Further, the photopolymerizable composition of the present invention preferably contains a suitable thermal polymerization inhibitor in order to prevent reactions in a dark place and to ensure stable storage for a long period of time.
Examples of this inhibitor include, for example, hydroquinone, hydroquinone monomethyl ether, hydroquinone monoethyl ether, hydroquinone monotert-butyl ether, benzoquinone, p-methoxyphenol, 2,5-diphenyl p-benzophenone, pyridine, phenothiazine, p-diamino Mention may be made of benzene, β-naphthol, naphthylamine, pyrogallol, tert-butylcatechol, nitrobenzene, and the like. These thermal polymerization inhibitors are usually used in an amount of 0.005 to 10% by weight based on the total weight of the photopolymerizable composition.

The photopolymerizable composition of the present invention may also contain fillers, plasticizers, and the like. Examples of the filler include inorganic compounds such as glass powder, mica, and silica, and examples of organic compounds include polyethylene, polyethylene oxide, polyester, polyamide, polymethacrylate, cellulose, and derivatives thereof.

These fillers must be selected to have good compatibility with the components of the photopolymerizable composition, and fillers can be used in combination depending on the purpose. Further, the amount can be selected within an appropriate range depending on the purpose of the photosensitive resin composition.

On the other hand, as the plasticizer, phosphate ester plasticizers such as phthalic acid dialkyl ester, oligoethylene glycol monoalkyl ester, oligoethylene glycol dialkyl ester, tricresyl phosphate, etc. can be used. In addition, any low-molecular organic compound that is compatible with the polymer having an ethylenically unsaturated group and a water-soluble salt group in the side chain constituting the photopolymerizable composition of the present invention can be used as a plasticizer. can be used.

The photosensitive liquid of the present invention can be obtained by dissolving the photopolymerizable composition components in the following solvents. The solvent for preparing the photosensitive liquid includes at least the above-mentioned polymer having an ethylenically unsaturated group and a water-soluble salt group, a photopolymerizable ethylenically unsaturated compound,
It is necessary to have the ability to dissolve both the photopolymerization initiator and the thermal polymerization inhibitor. In this case, depending on the combination of the four components, a mixed solvent consisting of two or more components may be required. From this point of view, examples of solvents suitable for preparing the photopolymerizable composition solution of the present invention include esters, ketones, alcohols, ethers, aromatic hydrocarbons, and the like. especially,
Ethyl acetate, methyl ethyl ketone, n-butyl alcohol, t-butyl alcohol, dioxane,
Benzene or mixtures thereof are suitable.

On the other hand, the concentration of the photopolymerizable composition contained in the photosensitive solution varies depending on the method and conditions of application of the photosensitive solution to the base material, but for example, when making an offset PS plate by wheeler coating, approximately 2～20
Weight % is appropriate.

A photosensitive liquid from the composition of the present invention can be produced by kakimaze mixing the photopolymerizable composition components and a solvent in a conventional mixing tank using a conventional method.

The photosensitive liquid produced in this way is generally
It is applied to aluminum plates, zinc plates, magnesium plates, and other metal plates for multilayer planography, which are used as substrates for offset printing. When applying the photosensitive liquid, the application method is a rotary coating machine (Whirler).
It is possible to perform sheet coating or web coating using a curtain coater, roll coater, etc.

The raw plate coated with the photosensitive resin composition of the present invention is
It can be baked in the same process as a normal lithographic plate and developed using only water, and an arc lamp, mercury lamp, xenon lamp, chemical lamp, etc. can be used as the active light source. Further, since development can be carried out using only water, various problems caused by the use of solvents and alkalis are solved.

The plate-making process consists of exposure, development, water washing, drying, and desensitization treatment, and an offset printing plate is created through the above steps. Furthermore, in the case of a multilayer planographic plate, a bimetallic or trimetallic printing plate can be obtained by performing corrosion and film peeling treatments after development.

As described above, the photosensitive resin composition of the present invention can be widely used as a photosensitive material for offset PS plates, Wipon plates, etching plates (Deep Etch Plates), and plano relief plates, and is also useful as various resists. It is.

Next, the present invention will be explained in detail with reference to Examples, but these are not intended to limit the present invention in any way.

Example 1 After stirring, 100 g of isopropyl alcohol as a reaction solvent was placed in a 500 ml four-necked flask equipped with a reflux condenser, a dropping funnel, and a thermometer, and heated to 80° C. while purging with nitrogen. Add 30 g of acrylonitrile and 30 g of butyl acrylate to the dropping funnel.
g, 30 g of acrylic acid, 10 g of styrene, and 3 N,N'-azobisisobutyronitrile as a polymerization catalyst.
The mixture was added dropwise over 2 hours and 30 minutes, and the reaction was completed by heating at 80° C. for 5 hours and 30 minutes. The mixture was cooled to 60°C and then added with 96 g of isopropyl alcohol,
0.3 g of hydroquinone was added as a polymerization inhibitor, and 3.75 g of a 40% methanol solution of trimethylbenzylammonium hydroxide was added as a reaction catalyst. Next, after raising the temperature of the contents to 80℃, glycidyl methacrylate 30 containing 0.3g of hydroquinone
g was added dropwise over 1 hour, and the reaction was continued for an additional 4 hours. After cooling to room temperature, a pale yellow viscous polymer solution was obtained. Addition reaction rate of glycidyl methacrylate (to carboxyl group) of the obtained polymer
was 68%.

The polymer thus obtained was mixed with 93.3 g of a 1N sodium hydroxide ethanol solution with stirring to give a neutralization degree of 0.7.

250 g of the polymer solution thus obtained was diluted with a mixed solvent consisting of 1300 ml of n-butyl alcohol, 200 ml of benzene and 200 ml of ethyl acetate, and 25 g of pentaerythritate tetramethacrylate was added as a crosslinking agent and β-ethylanthraquinone as a photosensitizer. 0.9 g and 0.1 g of benzoin methyl ether were added and stirred well to prepare a photopolymerizable composition solution for water development.

This solution was applied with a foiler onto a 0.3 mm aluminum plate that had been thoroughly washed and dried, and then dried and laminated with a 9 μm polyethylene terephthalate film.

The plate thus obtained was exposed with a 2 Kw ultra-high pressure mercury lamp from a distance of 1 m for 20 seconds in a vacuum printing frame with a negative film attached.

Developed with ordinary water (tap water) to obtain clear image lines. This plate was attached to an offset printing machine (Komori Sprint) and 50,000 sheets were printed using black ink (F Gloss No. 85, manufactured by Dainippon Ink). As a result, the ink receptivity at the beginning of printing was good, and there was no background smearing, uneven printing, chipping, etc., and good printed matter was obtained.

Example 2 A base polymer was produced in the same manner as in Example 1 using a monomer mixture having the following composition.

Acrylic nitrile 30g Butyl acrylate 30g Methacrylic acid 30g Vinyl acetate 10g After the polymerization reaction was completed, an addition reaction of glycidyl methacrylate to the base polymer was carried out in the same manner as in Example 1. The addition reaction rate (with respect to carboxyl groups) of glycidyl methacrylate in the obtained polymer was 70%.

The polymer thus obtained was mixed with 83.7 g of a 1N potassium hydroxide ethanol solution in the same manner as in Example 1, and the degree of neutralization was set to 0.8.

A photopolymerizable composition solution for water development was prepared in the same manner as in Example 1 using 250 g of the polymer solution obtained here, 25 g of trimethylolpropane triacrylate and 1 g of Michaelasketone as a crosslinking agent and photosensitizer. .

Except for using the photopolymerizable composition solution thus obtained, an original plate was prepared in the same manner as in Example 1, exposed to light, and developed with water. Clear image lines with high resolution were obtained. Further, when 50,000 sheets were printed in the same manner as in Example 1, good prints with good ink receptivity were obtained.

Example 3 A base polymer was produced in the same manner as in Example 1 using a monomer mixture having the following composition.

Acrylic nitrile 30g Styrene 10g Butyl acrylate 30g Acrylic acid 30g After the polymerization reaction is completed, glycidyl methacrylate 30g
An addition reaction of glycidyl acrylate as a base polymer was carried out in the same manner as in Example 1 except that 27 g of glycidyl acrylate was used instead of 27 g of glycidyl acrylate. Addition reaction rate of glycidyl acrylate (to carboxyl group) of the obtained polymer
was 62%.

The polymer thus obtained was mixed with 126.7 g of a 1N sodium hydroxide ethanol solution in the same manner as in Example 1, and the degree of neutralization was adjusted to 0.8.

To 250 g of this polymer solution, 25 g of tetraethylene glycol dimethacrylate and 1 g of benzophenone were added as a crosslinking agent and a photosensitizer, respectively.
A photopolymerizable composition solution was prepared in the same manner as in Example 1.

The photopolymerizable composition solution thus obtained was applied onto a copper plate and dried to obtain a film thickness of 2 μm. When this was exposed in a vacuum printing frame in the same manner as in Example 1 and then developed with tap water, an image with high resolution was obtained. When this copper plate was immersed in a corrosive solution, no abnormalities were observed in the lines.

Claims (1)

[Scope of Claims] 1. A photopolymerizable composition comprising a polymer having an ethylenically unsaturated group and a water-soluble salt group in its side chain, a photopolymerizable unsaturated compound containing an ethylenically unsaturated group, and a photopolymerization initiator. In the above-mentioned polymer, an oxirane ring-containing ethylenically unsaturated compound in an amount of 0.03 to 0.85 equivalent to the carboxyl group is added to the polymer containing 5% by weight or more of unsaturated carboxylic acid as a constituent unit, and the remaining carboxyl group is A water-developable photopolymerizable composition characterized by using a polymer in which 0.60 to 1.00 equivalents of groups are neutralized to form an alkali metal salt or an ammonium salt. 2 A polymer containing 5% by weight or more of unsaturated carboxylic acid as a constituent unit contains 5 to 70% by weight of at least one unsaturated carboxylic acid selected from acrylic acid and methacrylic acid, a styrene compound, and an unsaturated nitrile. The composition according to claim 1, which is a polymer comprising 95 to 30% by weight of at least one ethylenically unsaturated compound selected from unsaturated carboxylic acid esters, unsaturated carboxylic acid esters, and fatty acid vinyl esters. 3. The composition according to claim 1, wherein the oxirane ring-containing ethylenically unsaturated compound is glycidyl acrylate or glycidyl methacrylate.