JP2805802B2 - Method for producing polyurethane resin for photosensitive composition - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing a polyurethane resin for a photosensitive composition, and more particularly, to a method for producing a photosensitive composition for a photosensitive lithographic printing plate. The present invention relates to a method for producing a polyurethane resin for a photosensitive composition, wherein the production efficiency is improved, the pollution problem does not occur, and the production cost is low.

[Conventional technology]

Conventionally, many image forming methods using a photopolymerizable composition are known. For example, a photosensitive composition comprising an addition-polymerizable ethylenically unsaturated compound, a photopolymerization initiator, and, if necessary, an organic polymer binder, a diazo resin, a colorant, and a stabilizer is prepared. There is known a method of preparing a photosensitive material provided with a layer of a photosensitive composition by applying the composition on a support without solvent or by dissolving it in an organic solvent. The photosensitive material can be image-exposed with actinic rays to cure the exposed portions, and the unexposed portions can be removed with a developer to form a cured relief image.

Such a photopolymerizable composition has been conventionally used for forming various images such as a photosensitive lithographic printing plate, a photosensitive resin relief plate, a screen printing plate, a photoresist, and a color proof.

When the photopolymerizable composition is used as a photosensitive image forming layer suitable for an aqueous alkali developable photosensitive lithographic printing plate,
Generally, alkali-soluble or swellable organic polymer binders are commonly used.

Examples of such an organic polymer binder include, for example, an addition polymer having a carboxyl group in a side chain (for example, a copolymer of methacrylic acid and another vinyl compound; a partially esterified maleic acid copolymer and the like), Addition polymers having an ethylenically unsaturated bond and a carboxyl group in the side chain (eg, a carboxyl group-containing vinyl copolymer with a portion of an ethylenically unsaturated compound containing an oxirane ring added; allyl methacrylate and methacrylic acid) And polyvinyl acetal resins and modified products thereof (eg, cyclic acid anhydride adducts; alkyl phosphinic acid isocyanate adducts; isopropenyl sulfonyl isocyanate adducts); polyurethane resins having a carboxyl group in the side chain , Polyurethane resin having ethylenically unsaturated bond and carboxyl group in side chain Etc. have been known.

Among these, the photopolymerizable composition containing a polyurethane resin having an allyl group and a carboxyl group in the side chain can be developed with an aqueous alkaline developer, is less susceptible to polymerization inhibition by oxygen, has abrasion resistance, It is applied to lithographic printing plates with high printing durability.

As a method for producing this polyurethane resin, generally,
In an organic solvent, by a polyaddition reaction of a diol compound having a carboxyl group and a diisocyanate compound, to produce a polyurethane resin having a carboxyl group in a side chain,
Next, a part of the carboxyl group is reacted with an allyl group-containing halogen compound in the presence of a base. Further, in order to remove by-products, a process of throwing into a large amount of water, separating and purifying by precipitation, and drying is adopted.

[Problems to be solved by the invention]

However, these production processes were not suitable for industrial mass production. In the step of separation and purification,
There are problems such as odor at the time of work and safety to the human body, and it is necessary to treat a large amount of wastewater containing an organic solvent. Further, a large-sized drying facility is required to dry the water-containing polyurethane resin. As a result, the resulting polyurethane resin was expensive.

In addition, since the introduction of the allyl group is a polymer reaction, there is a problem that it is difficult to control the introduction ratio and it is difficult to obtain a polyurethane resin having stable quality.

Furthermore, when a photosensitive solution is prepared using this separated and purified polyurethane resin and applied to a support, coating unevenness, cissing, spots, etc., which are considered to be caused by a trace amount of impurities remaining in the polyurethane resin, are likely to occur. There was a problem.

That is, an object of the present invention is to provide a method for producing a polyurethane resin having an allyl group and a carboxyl group in a side chain which is industrially simple. Further, another object of the present invention is to reduce the generation of odor during production, have no adverse effect on the human body, and do not emit a large amount of organic solvent-containing wastewater.
Also, there is no need for equipment for drying the resin, that is,
An object of the present invention is to provide a method for producing an inexpensive polyurethane resin. Further, another object of the present invention is a photosensitive composition, particularly when used in a photosensitive composition of a photosensitive lithographic printing plate, coating properties,
An object of the present invention is to provide a method for producing a polyurethane resin capable of improving quality such as stability over time.

[Means for solving the problem]

In order to solve the above problems, the present invention provides a side chain comprising reacting (1) a diisocyanate compound, (2) a diol compound having an allyl group, and (3) a diol compound having a carboxyl group in an organic solvent. The present invention provides a method for producing a polyurethane resin for a photosensitive composition having an allyl group and a carboxyl group.

As the diisocyanate compound used in the present invention,
For example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-xylylene diisocyanate,
Aromatic diisocyanate compounds such as meta-xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate; aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, dimer acid diisocyanate Compounds; alicyclic diisocyanate compounds such as isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4 (or 2,6) diisocyanate, and 1,3- (isocyanatomethyl) cyclohexane; And diisocyanate compounds derived from diols and diisocyanates, such as adducts of 1 mol of 3-butylene glycol and 2 mol of tolylene diisocyanate. .

Examples of the diol compound having an allyl group include, for example,
Glycerol α-monoallyl ether, trimethylolpropane monoallyl ether, pentaerythritol diallyl ether, N, N-diallyl tartaric acid diamide and the like can be mentioned.

Examples of the diol compound having a carboxyl group include, for example, 2,2-bis (hydroxylmethyl) propylonic acid,
2,2-bis (hydroxyethyl) propionic acid, 2,2-bis (3-hydroxypropyl) propionic acid, bis (hydroxymethyl) acetic acid, 3,5-dihydroxybenzoic acid, bis (4-hydroxyphenyl) acetic acid, 4,4-bis (4-hydroxyphenyl) pentanoic acid, tartaric acid, N, N-bis (2
-Hydroxyethyl) 3-carboxypropionamide and the like.

Further, a diol compound having no allyl group or carboxyl group can be used in combination. Such diol compounds include, for example, ethylene glycol,
Diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, polypropyne glycol, neopentyl glycol, 1,3-butylene glycol, 1,6-hexanediol, 2-butene-1,
4-diol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-bis-β-bidoxyethoxycyclohexane, cyclohexanedimethanol, tricyclodecanedimethanol, hydrogenated bisphenol A, hydrogenated bisphenol
F, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, ethylene oxide adduct of bisphenol F, propylene oxide adduct of bisphenol F, ethylene oxide adduct of hydrogenated bisphenol A, hydrogenated bisphenol A
Propylene oxide adduct, hydroquinone dihydroxyethyl ether, p-xylylene glycol, bis (2
-Hydroxyethyl) isophthalate, hydroquinone,
Examples include bisphenol A and bisphenol F.

The polyurethane resin of the present invention is synthesized by adding a catalyst, if necessary, to the diisocyanate compound, the diol compound having an allyl group and the diol compound having a carboxyl group in an organic solvent, and then heating the mixture at room temperature or under heating. The usage ratio of the diisocyanate compound and the diol component is preferably in a range of 0.7 to 1.3 mol per 1 mol of the diisocyanate compound. When the diol component is less than 0.7 mol or more than 1.3 mol, the molecular weight of the polyurethane resin is not sufficiently increased, and sufficient printing durability tends not to be obtained. The proportion of the diol compound having an allyl group is preferably selected so that the content of the allyl group is 0.3 mol or more per 1000 g of the polyurethane resin. If less than 0.3 mol,
It is not preferable because the printing plate tends to be easily inhibited by oxygen and a printing plate having high printing durability tends not to be obtained. The proportion of the diol compound having a carboxyl group is preferably selected so that the acid value of the polyurethane resin is 10 to 200. When the acid value of the polyurethane resin is less than 10, the developability with the aqueous alkali developer is insufficient, and when the acid value of the polyurethane resin exceeds 200, the oil sensitivity and printing durability tend to decrease. Is not preferred.

In the above reaction, for example, dibutyltin dilaurate, dibutyltin diacetate, triethylamine, morpholine and the like can be used as a urethanization catalyst.

Examples of the organic solvent that can be used in the above reaction include methylene chloride, chloroform, dichloroethane, trichloroethane, trichloroethylene, monochlorobenzene,
Halogen solvents such as dichlorobenzene and carbon tetrachloride; hexane, heptane, cyclohexane, benzene,
Aliphatic or alicyclic or aromatic hydrocarbon solvents such as toluene and xylene; tetrahydrofuran, dioxane,
Ether solvents such as diethyl ether, ethyl propyl ether, dibutyl ether, ethylene glycol dimethyl ether; ester solvents such as glycol methyl ether acetate, glycol ethyl ether acetate, methyl acetate, ethyl acetate, butyl acetate;
Acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4-methyl-4-methoxy-2-
Ketone solvents such as pentanone; nitrogen-containing solvents such as acetonitrile, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, nitrobenzene and the like; dimethylsulfoxide and the like. These solvents may be used alone or in combination of two or more. You can also.

When an isocyanate group remains at the polymer terminal in the above reaction, it is preferable to inactivate an unreacted isocyanate group by treating with an alcohol, an amine or the like.

According to the method of the present invention described above, the weight average molecular weight
A polyurethane resin solution having an allyl group and a carboxyl group in the side chain of 2,000 to 150,000 can be easily produced.

In the polyurethane resin solution thus obtained,
A photopolymerization initiator is added, and an addition-polymerizable ethylenically unsaturated compound, a diazo resin, a colorant, a stabilizer, and the like are added as necessary. This is a photopolymerizable composition for a lithographic printing plate.

Examples of the photopolymerization initiator include α-carbonyl compounds described in US Pat. No. 2,666,661, acyloin ethers described in US Pat. No. 2,448,828, and US Pat. No. 2,722,512. Has been α
Hydrocarbon-substituted aromatic acyloin compounds, polyquinone compounds described in U.S. Pat. No. 3,046,127, and triarylbiimidazole / p-aminophenyl ketones described in U.S. Pat. No. 3,493,367. A trihalomethyl-S-triazine-based compound described in U.S. Pat. No. 4,239,850, U.S. Pat.
Oxadiazole compounds described in 4212970, acridine and phenazine compounds described in U.S. Pat. No. 3,751,259, benzothiazole compounds described in JP-B-51-48516, and the like. The amount used is 0.5 to 20 with respect to the solid content of the composition.
A range of weight% is preferred.

The ethylenically unsaturated compound capable of addition weight is a monomer or oligomer having a boiling point of 100 ° C. or more at normal pressure and having at least one, preferably two or more addition-polymerizable ethylenically unsaturated groups in one molecule. is there. As such a monomer or oligomer, for example, polyethylene glycol mono (meth) acrylate [hereinafter, methacrylate and acrylate are collectively referred to as (meth) acrylate]. Monofunctional (meth) acrylates such as polypropylene glycol mono (meth) acrylate and phenoxyethyl (meth) acrylate; polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, Neopentyl glycol di (meth) acrylate, pentaerythritol tri (meth)
Acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, hexanediol di (meth) acrylate, tri (acryloyloxyethyl) isocyanurate, (meth) acrylate of polyhydric alcohol / alkylene oxide adduct, (Meth) acrylate of polyhydric phenol / alkylene oxide adduct, JP-B-48-41
No. 708, Japanese Patent Publication No. 50-6034, and urethane acrylates described in JP-A-51-37193, JP-A-48-64
No. 183, JP-B-49-43191 and JP-B-52-30490, polyfunctional (meth) acrylates such as polyester acrylates and epoxy acrylates obtained by adding epoxy resin and (meth) acrylic acid. Can be mentioned.

The use amount of these addition-polymerizable ethylenically unsaturated compounds is preferably in the range of 0 to 70% by weight based on the solid content of the composition.

As the diazo resin, there is a diazo resin represented by a salt of a condensate of a diazodiarylamine and an active carbonyl compound, and a photosensitive, water-insoluble and organic solvent-soluble resin is preferable.

Particularly preferred diazo resins are 4-diazodiphenylamine, 4-diazo-3-methyldiphenylamine, 4-diazo-4'-methyldiphenylamine, 4-diazo-
3'-methyldiphenylamine, 4-diazo-4'-methoxydiphenylamine, 4-diazo-3-methyl-
Organic or inorganic acid salts of condensates of 4'-ethoxydiphenylamine, 4-diazo-3-methoxydiphenylamine, etc. with formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, 4,4'-bis-methoxymethyldiphenyl ether, etc. .

Examples of the organic acid include methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, mesitylenesulfonic acid, dodecylbenzenesulfonic acid, naphthalenesulfonic acid, propylnaphthalenesulfonic acid, 1-naphthol-5-sulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 2
-Vidoxy-4-methoxybenzophenone-5-sulfonic acid, 2,4-dihydroxybenzophenone, benzenephosphinic acid, and the like.Examples of the inorganic acid include hexafluorophosphoric acid, tetrafluoroboric acid, and thiocyanic acid. .

Further, a diazo resin having a main chain of a polyester group described in JP-A-54-30121; a polymer having a carboxylic anhydride residue described in JP-A-61-273538, and a diazo resin having a hydroxyl group. A diazo resin obtained by reacting a compound; a diazo resin obtained by reacting a polyisocyanate compound with a diazo compound having a hydroxyl group can also be used.

The amount of these diazo resins and the amount used are preferably in the range of 0 to 40% by weight based on the solid matter of the composition, and if necessary, two or more kinds of diazo resins may be used in combination.

Further, another organic polymer binder may be used in combination in an amount of 50% by weight or less based on the polyurethane resin of the present invention. Examples of such an organic polymer binder include acrylic resin, polyamide resin, polyester resin, epoxy resin, polyacetal resin, polystyrene resin, and novolak resin.

Further, in order to improve the performance, known additives such as a thermal polymerization inhibitor, a dye, a pigment, a surfactant, a plasticizer, and a stability improver can be added.

Suitable dyes include, for example, basic oil-soluble dyes such as crystal violet, malachite green, Victoria blue, methylene blue, ethyl violet, and rhodamine B. As a commercial product, for example,
"Victoria Pure Blue BOH" (manufactured by Hodogaya Chemical Industry Co., Ltd.), "Oil Blue # 603" (manufactured by Orient Chemical Industry Co., Ltd.) and the like. Examples of the pigment include phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone red, and the like.

Examples of the surfactant include an anionic surfactant, a nonionic surfactant, and a fluorine-based surfactant.

Examples of the plasticizer include diethyl phthalate, dibutyl phthalate, dioctyl phthalate, tributyl phosphate, triocultyl phosphate, tricresyl phosphate, tri (2-chloroethyl) phosphate, tributyl citrate,
And the like.

Further, as known stability improvers, for example, phosphoric acid, phosphorous acid, oxalic acid, tartaric acid, malic acid, citric acid, dipicolinic acid, polyacrylic acid, benzenesulfonic acid, toluenesulfonic acid and the like can be used in combination.

The amounts of these various additives vary depending on the purpose, but generally, the range of 0.01 to 30% by polymerization of the solid content of the photopolymerizable composition for a lithographic printing plate of the present invention is preferable.

Further, a coating solvent can be added as needed. Examples of such a coating solvent include an organic solvent used for producing the above-mentioned polyurethane resin; methanol, ethanol, propanol, butanol, tetrahydrofurfuryl alcohol, benzyl alcohol, diacetone alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl. Ether, propylene glycol monomethyl ether, ethylene glycol monophenyl ether, cyclohexanol and the like are suitable, and a mixed solvent thereof is suitable. In some cases, a mixed solvent with water can also be used.

The photopolymerizable composition for a lithographic printing plate manufactured in this manner is supported by a known coating method such as dip coating, curtain coating, roll coating, spray coating, wheeler coating, spinner coating, air knife coating, doctor knife coating, and the like. Applied to the body.

As the support, for example, aluminum, zinc, copper,
Metal plate of stainless steel, iron, etc .; plastic film of polyethylene terephthalate, polycarbonate, polyvinyl acetal, polyethylene, etc .; paper coated with synthetic resin melted or coated with synthetic resin solution, metal layer on plastic film by vacuum evaporation, lamination, etc. Provided composite material; and other various materials used as a support for a printing plate. In the case of a support having a metal surface, particularly an aluminum surface, it is preferable that a surface treatment such as a graining treatment, an anodic oxidation treatment, and a hydrophilic treatment is performed. The amount of coating is usually about 0.5 to about 5 g / m ² on a dry weight basis.

After coating, the coating is dried by a known method to obtain a photosensitive lithographic printing plate having a photosensitive amount provided on a support. The exposed portion of the photosensitive layer of the photosensitive lithographic printing plate is subjected to additional exposure with a negative image to cure the exposed portion of the photosensitive layer, to make it insolubilized, and then developed with an aqueous alkali developing solution to dissolve and remove the unexposed portion. A lithographic printing plate with the corresponding image formed on the body is obtained.

Suitable light sources used for exposure include, for example, carbon arc lamps, mercury lamps, metal halide lamps, xanon lamps, chemical lamps, lasers, and the like.

Examples of the aqueous alkaline developer include sodium silicate, potassium silicate, potassium hydroxide, sodium hydroxide, lithium hydroxide, tribasic sodium phosphate, dibasic sodium phosphate, tribasic ammonium phosphate, and sodium metasilicate. , Sodium carbonate, aqueous ammonia, monoethanolamine, diethanolamine, triethanolamine, diisopropanolamine, monomethylamine,
An aqueous solution containing an alkaline agent such as dimethylamine, triethylamine, or the like can be given. In order to further improve the solubility of the unexposed portion of the photosensitive layer and the permeability of the developer, anionic surfactants such as sodium isopropylnaphthalenesulfonate, sodium dodecylbenzenesulfonate, sodium salt of lauryl alcohol sulfate, and sodium dialkylsulfosuccinate are used. A solvent such as benzyl alcohol, N-benzylethanolamine, phenoxyethanol, diacetone alcohol, methyl cellosolve, or isopropyl alcohol can also be added.

Polyurethane resin produced by the method of the present invention,
Although it is extremely useful as a photopolymerizable composition for lithographic printing plates, it is not necessarily limited to this use, and is used for resin relief printing plates, screen printing plates, photoresists, color proofs, hologram forming materials, etc. Can also be used.

Hereinafter, the present invention will be described specifically with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist.

Examples 1 to 7 A reactor equipped with a cooling pipe and a stirrer was added with a diisocyanate compound, a diol compound having a carboxyl group, a thiol compound having an allyl group and a solvent in the amounts and types described in Table 1 to obtain a 40 wt. % Solution. While stirring in a dry nitrogen gas atmosphere, the temperature was gradually raised to 60 ° C. over 2 hours. Next, dibutyltin dilaurate was used as a catalyst.
0.5 g was added, and the mixture was further reacted at 90 ° C. until the ratio of reactive NCO became 0.5% or less (about 6 to 8 hours). Next, the temperature was lowered to 80 ° C., 10.0 g of methanol was added, and the mixture was treated for 2 hours to obtain a polyurethane resin solution having an allyl group and a carboxyl group in a side chain.

Acid value (solid content conversion value) and GP of this polyurethane resin
Table 1 shows the weight average molecular weight (in terms of polystyrene) measured by S analysis.

Further, as a result of NMR analysis and IR analysis, it was confirmed that an allyl group and a carboxyl group were introduced into the polyurethane resin.

Comparative Example 1 250 g (1.0 mol) of 4,4'-diphenylmethane diisocyanate, 134 g (1.0 mol) of 2,2-bis (hydroxymethyl) propionic acid and 580 g of dioxane were added to a reactor equipped with a cooling pipe and a stirring device. The mixture was stirred under a dry nitrogen gas atmosphere. N, N-diethylaniline (2 g) was added as a catalyst, and the mixture was heated and refluxed for 8 hours with stirring. Thereafter, the reaction solution was poured into a solution of water 8 and acetic acid 80 ml with stirring to precipitate a polymer. The polymer was filtered, washed with water, and dried under vacuum to obtain 370 g of a polyurethane resin having a carboxyl group in a side chain. As a result of GPC analysis, this polyurethane resin had a weight average molecular weight of 28,000, and an acid value of 138.
It was five.

Further, 80 g of this polyurethane resin was put into a reactor equipped with a cooling tube and a stirrer, and dissolved in 400 ml of dimethylformamide. To this solution was added 12.6 g of triethylamine (0.1
24 mol) and heated to 80 ° C., followed by allyl bromide 15.0
g (0.124 mol) was added dropwise over 10 minutes with stirring. Then, after continuing to stir for 2 hours, the reaction solution was water 8 and acetic acid 400m
The solution was poured into the solution (1) with stirring to precipitate a polymer. The polymer was filtered, washed with water, and dried under vacuum to obtain 82 g of a polyurethane resin having an allyl group and a carboxyl group in a side chain (Comparative polyurethane resin-1).

This polyurethane resin has an acid value of 67.0, and
As a result of NMR analysis and IR analysis, it was confirmed that an allyl group and a carboxyl group had been introduced.

Comparative Example 2 The same reaction was attempted in the same manner as in Example 1 except that the solvent dioxane was not used and the same raw materials were used as in Example 1. However, in the first hour of the reaction, the temperature rose rapidly due to heat generation, and stirring became difficult. The reaction was insoluble in all solvents.

Application example (1) Preparation of a photosensitive lithographic printing plate A 0.30 mm thick aluminum plate is coated with a nylon brush and 40
A 0-mesh aqueous suspension of pamistone is used to grain the surface, and then the current density is 2 A / dm ^{2 in a} 20% sulfuric acid electrolyte.
To form an oxide film of 2.7 g / m ² .
Thereafter, the support was immersed in a 3% aqueous solution of No. 3 sodium silicate at 60 ° C. for 1 minute, washed with water and dried to obtain a support.

The following photosensitive solution is applied to this support with a roll coater,
The photosensitive lithographic printing plate was obtained by drying at 100 ° C. for 2 minutes. At this time, the weight of the dried coating film was 2.0 g / m ² .

* 1) The diazo resin is a p-toluenesulfonic acid salt of a condensate of 4-diazodiphenylamine and paraformaldehyde.

* 2) Victoria Pure Blue BOH is a base oil-soluble dye manufactured by Hodogaya Chemical Industry Co., Ltd.

* 3) "MegaFac F-177" is a fluorine-based surfactant manufactured by Dainippon Ink and Chemicals, Inc.

(2) Preparation of a lithographic printing plate A film of a dot negative image and a step of 0.15 step wedge are brought into close contact with the photosensitive lithographic printing plate obtained in (1),
As a result, a metal halide lamp with an output of 1 kW (1 m from Iwasaki Electric Co., Ltd.)
0 ") for 85 seconds. Then, use the following developer
Development was performed at 5 ° C. for 1 minute to obtain a lithographic printing plate.

* 6) "Perex NBL" is a sodium alkylnaphthalenesulfonate anionic surfactant manufactured by Kao Atlas Co., Ltd.

(3) Evaluation of photosensitive lithographic printing plate and lithographic printing plate The coating properties of the photosensitive lithographic printing plate and the aging stability of the lithographic printing plate were evaluated. The results are shown in Table 1.

 The test conditions are shown below.

-Coating property: The coating state after coating and drying was visually observed and evaluated.

Stability over time: Store the photosensitive lithographic printing plate at 60 ° C. and 75% humidity for 3 days, and then expose under the same conditions as above.
Developed. Immediately before the production of the photosensitive lithographic printing plate, post-exposure and development were compared with those which were exposed and developed, and the presence or absence of background stain with the printing ink in the specific image area, developability and the like were evaluated.

Printing durability: A lithographic printing plate was prepared in the same manner as in (2), except that exposure was performed for an exposure time at which the light sensitivity became 5 steps. The lithographic printing was installed on a Roland Fabolit printing machine, and the printing ink "CAPS-G Beni" (Dainippon Ink and Chemicals Co., Ltd.)
DH-78) (Dainippon Ink Chemical Industry Co., Ltd.)
Printing was carried out using a 400-fold diluted solution of the company. At the time of printing 200,000 sheets, the evaluation was made based on whether or not a printed matter faithful to the original image could be obtained without causing halftone dot enlargement, skipping of a plate, or the like.

[Effect of the Invention] The present invention is an industrially simple method for producing a polyurethane resin having an allyl group and a carboxyl group in a side chain. At the time of production, there is little generation of odor and there is no generation of waste water containing a large amount of organic solvent, so there is no problem of pollution, and since no equipment for drying the resin is required, an inexpensive polyurethane resin can be obtained. Furthermore, when the polyurethane resin produced according to the present invention is used for a photosensitive composition, particularly for a photosensitive lithographic printing plate, a product having improved quality such as coating properties and stability over time can be obtained.

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Claims (1)

(57) [Claims] An allyl group and a carboxyl group on a side chain, wherein (1) a diisocyanate compound, (2) a diol compound having an allyl group and (3) a diol compound having a carboxyl group are reacted in an organic solvent. A method for producing a polyurethane resin for a photosensitive composition having a group.