JP2808204B2 - Manufacturing method of photosensitive lithographic printing plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a photosensitive lithographic printing plate. More specifically, the present invention relates to a method for producing a photosensitive lithographic printing plate excellent in inking property.

[0002]

2. Description of the Related Art The majority of those used as photosensitive materials in photosensitive lithographic printing plates to which photosensitivity has been given in advance are diazonium compounds. Among them, the most commonly used one is formaldehyde condensation of p-diazodiphenylamine. There is a diazo resin represented by a product. The composition of the photosensitive layer of a photosensitive lithographic printing plate using a diazo resin is, for example, as described in U.S. Pat. No. 2,714,066, a diazo resin alone, that is, one without a binder. And a mixture of a binder and a diazo resin as described in, for example, JP-A-50-30604. In particular, in recent years, many photosensitive lithographic printing plates using a diazonium compound have a photosensitive layer composed of a binder and a diazo resin in order to impart high printing durability. Such a photosensitive layer is disclosed in JP-A-50-3060.
As described in JP-A No. 4 (KOKAI) No. 4, there is known a so-called alkali developing type in which an unexposed portion is removed (developed) by an aqueous alkaline developing solution and a so-called solvent developing type in which an unexposed portion is removed by an organic solvent-based developing solution. . In recent years, on occupational safety and health,
Attention has been paid to the alkali development type, which is mainly determined by the properties of the binder. As a method for imparting alkali developability to a binder, a method of copolymerizing a carboxylic acid-containing monomer as described in JP-A-50-30604, U.S. Pat. No. 2,861,058 And a method of introducing a carboxylic acid into a binder by reacting a hydroxyl group of polyvinyl alcohol with a cyclic acid anhydride such as phthalic anhydride. However, the obtained photosensitive layer was insufficient in the inking property, which is an important property of the lithographic printing plate. Thus, in order to improve the inking property, a method of adding a polymer compound having a higher oil sensitivity than a binder as described in JP-A-55-527 has been proposed. Insufficient, and further improvement was desired.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a photosensitive lithographic printing plate which can be alkali-developed and further improved the inking property.

[0004]

The present inventors have conducted various studies to achieve the above object, and as a result, have found that a diazo resin, a binder and a polymer compound of a copolymer having a structural unit represented by the following general formula can be obtained. The negative photosensitive composition is dissolved in a coating solvent containing (a) 1-methoxy-2-propanol: 5 to 40% by weight and (b) methyl lactate: 2 to 20% by weight to have a hydrophilic surface. It has been found that a photosensitive lithographic printing plate satisfying the above objects can be manufactured by applying a polymer compound having the following general formula, which is higher in oil sensitivity than a binder, to the photosensitive layer surface by coating and drying the support. Was.

Embedded image R ¹ represents a methyl group, an ethyl group, a methoxy group, an ethoxy group or an aryl group. R ² and R ^{3 each} have 2 to 20 carbon atoms.
Represents an alkyl group or an aryl group. R ² and R ³ may be the same or different. The ratio of A is 20 to 8 in molar ratio.
The range is 0%. The ratio of B is in the range of 20 to 80% by molar ratio. The ratio of C is in the range of 0 to 20% in molar ratio. The ratio of D ranges from 0 to 20% by mole.

The polymer having a structural unit represented by the above general formula used in the present invention has a function of improving the oil sensitivity of a photosensitive lithographic printing plate, and is a polymer compound having higher oil sensitivity than a binder. It is. Examples of the aryl group represented by R ^{1 in} the general formula include groups such as a phenyl group, a chlorophenyl group, a chloromethylphenyl group, a xylyl group and a cumenyl group, and a bicyclic aryl group such as a naphthyl group. However, a phenyl group is particularly preferred. Also,
The alkyl group of R ² and R ³ has 2 to 20 carbon atoms, preferably 3 to 10 carbon atoms. Specifically, for example, n-propyl group, isopropyl group, butyl group, tert-butyl group, n-hexyl group, 2-ethylhexyl group, 1,3-dimethylbutyl group, n-octyl group,
Examples thereof include an n-tridecyl group. Of these, particularly preferred are a butyl group, an n-hexyl group, a 2-ethylhexyl group, a 1,3-dimethylbutyl group, and an n-octyl group. The aryl group of R ² includes, for example, a monocyclic group such as a phenyl group and a chlorophenyl group, and a bicyclic group such as a naphthyl group. The ratio of the component A in the copolymer having the structural unit represented by the general formula is in the range of 20 to 80% by molar ratio. Preferably 3
It is in the range of 0-70%. When it is 20% or less, the effect of improving the inking property is small. Conversely, if the content is 80% or more, the developability deteriorates. The ratio of the component B is in the range of 20 to 80% by mole ratio. Preferably it is in the range of 30 to 70%. When the content is less than 20%, the solubility in an alkali developing solution is reduced and scum is generated. On the other hand, when it is 80% or more, the image intensity at the time of development is reduced. The ratio of the C component and the D component is 0 to 20 in a molar ratio.
% Range. Preferably it is in the range of 0 to 10%.
When the content is 20% or more, the developability deteriorates. The weight average molecular weight of the copolymer is generally in the range of about 500 to 500,000, preferably in the range of 800 to 300,000, and most preferably 1,000 to 20,000.
0. The above-mentioned copolymer is contained in the photosensitive layer in an amount of 0.01 to 20% by weight, more preferably 0.1 to 5.0% by weight.

The diazo resin used in the present invention is a diazo resin represented by a condensate of an aromatic diazonium salt and an active carbonyl group-containing compound such as formaldehyde. As the diazo resin, for example, an organic solvent-soluble diazo resin inorganic salt which is a reaction product of a condensate of p-diazodiphenylamines with an aldehyde such as formaldehyde or acetaldehyde and hexafluorophosphate or tetrafluoroborate, Tokiko 47-1167
Sulfonic acid salts with the condensate as described in JP-A No. H10-260, such as p-toluenesulfonic acid or a salt thereof,
Organic solvent soluble as a reaction product with propylnaphthalenesulfonic acid or a salt thereof, butylnaphthalenesulfonic acid or a salt thereof, dodecylbenzenesulfonic acid or a salt thereof, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid or a salt thereof And diazo resin organic salts. In particular, a high molecular weight diazo compound containing at least 20 mol% of a hexamer or more described in JP-A-59-78340 is preferable. Further, 3-methoxy-4-diazo-diphenylamine condensed with 4,4'-bis-methoxy-methyl-diphenyl ether to give a mesitylene sulfonate as disclosed in JP-A-58-27141. Appropriate.

The binder used in the present invention has an acid content of 0.1 to 3.0 meq / g [milli-equivalent of the acid component per 1 g of the binder], preferably 0.2 to 2.0 meq / g. Yes, practically insoluble in water (ie, insoluble in neutral or acidic aqueous solutions)
An organic polymer compound having a film-forming property is preferable, but can be dissolved or swelled in an alkaline aqueous solution-based developer and is photo-cured in the presence of the photosensitive diazo resin to become insoluble or non-soluble in the developer. Those that swell are preferred. When the acid content is less than 0.1 meq / g, development is difficult, and when the acid content exceeds 3.0 meq / g, the image intensity during development is significantly reduced. Particularly preferred binders are copolymers containing acrylic acid, methacrylic acid, crotonic acid or maleic acid as an essential component, for example, 2-hydroxyethyl acrylate or 2 copolymer described in JP-A-50-118802. -Hydroxyethyl methacrylate, acrylonitrile or methacrylonitrile, multi-component copolymers with acrylic acid or methacrylic acid and optionally other copolymerizable monomers, such as those described in JP-A-53-120903. The terminal is a hydroxy group,
And a multi-component copolymer of acrylic acid or methacrylic acid, acrylic acid, or methacrylic acid esterified with a group containing a dicarboxylic acid ester residue, and optionally other copolymerizable monomers; No. 98614, a monomer having an aromatic hydroxyl group at its terminal (for example, N- (4-hydroxyphenyl) methacrylamide, etc.), acrylic acid or methacrylic acid and, if necessary, other monomers. Examples thereof include a multi-component copolymer with a polymerizable monomer and a multi-component copolymer comprising an alkyl acrylate, acrylonitrile or methacrylonitrile and an unsaturated carboxylic acid as described in JP-A-56-4144. . Alternatively, acidic polyvinyl alcohol derivatives and acidic cellulose derivatives are also useful. JP-B-54-19773, JP-A-57-94747, JP-A-60-182437 and JP-A-60-182737 in which polyvinyl acetal or polyurethane is alkali-solubilized.
The binders described in -58242 and 62-123453 are also useful. The content of the diazo resin and the binder in the photosensitive layer of the photosensitive lithographic printing plate is 3 to 30% by weight of the diazo resin and 97 to 100% by weight of the binder based on the total amount of both.
70% by weight is suitable. When the content of the diazo resin is small, the sensitivity is high, but when the content is lower than 3% by weight, it is insufficient for photocuring the binder, and the photocured film swells with the developing solution during development, and the film becomes weak. Conversely, if the content of the diazo resin is more than 30% by weight, the sensitivity is lowered and practical difficulties arise. Therefore, a more preferable range is 5 to 25% by weight of the diazo resin and 95 to 75% by weight of the binder.

In the present invention, the proportion of 1-methoxy-2-propanol of the component (a) in the coating solvent is 5 to 5%.
It is 40% by weight, preferably 10 to 30% by weight. The optimum amount varies depending on the drying conditions and the type of the binder, and further on the content of methyl lactate. However, when the content of 1-methoxy-2-propanol is less than 5% by weight or more than 40% by weight, the lipophilic The high polymer compound is less likely to be unevenly distributed on the surface of the photosensitive layer, and the effect of improving the inking property is small. 5 to 40% by weight of 1-methoxy-2-propanol in the coating solution
The incorporation was greatly improved by the use, but surprisingly, it was found that the incorporation was further improved when methyl lactate was used in combination. The proportion of methyl lactate of the component (b) in the coating solvent in the present invention is 2 to 20% by weight, preferably 5 to 15% by weight. When the content of methyl lactate is less than 2% by weight, the effect of improving the inking property is small. On the other hand, when the content is more than 20% by weight, the developability deteriorates. When the content is more than 15% by weight, the boiling point of methyl lactate is 1
At 44.8 ° C., unless a large amount of drying energy is applied, the highly oil-sensitive polymer compound is less likely to be unevenly distributed on the surface of the photosensitive layer, and the effect of improving the inking property is small.

Various other solvents can be mixed with the coating solvent in the present invention. It is preferable to mix a low-boiling-point solvent in order to dry with a small drying energy and to unevenly disperse the high oil-sensitive polymer compound on the surface of the photosensitive layer.
Specific examples of the low boiling point solvent include 1,2-dichloroethane,
1,1-dichloroethane, 1,1,1-trichloroethane, ci
halogenated hydrocarbons such as s-1,2-dichloroethane, 1,2-dichloropropane, butyl chloride, and chromium bromomethane; methanol, ethanol, n-propanol, isopropanol, secondary butyl alcohol, and tertiary butyl alcohol Aliphatic alcohol, tetrahydrofuran,
Ether or ketone compound such as tetrahydropyran, ethylene glycol dimethyl ether, acetone, methyl ethyl ketone, ethyl formate, propyl formate, isobutyl formate, methyl acetate, ethyl acetate, isopropyl acetate,
Ester compounds such as methyl propionate and ethyl propionate are exemplified. Low boiling point solvent content is 40-8
0% by weight is preferred. A small amount of water can be further added to the coating solvent in the present invention. The amount of water added is 10% by weight or less of the total solvent. Preferably it is 1 to 7% by weight.

A small amount of a high boiling point solvent can be further added to the coating solvent in the present invention for the purpose of increasing the solubility of the photosensitive diazo resin and improving the compatibility between the photosensitive diazo resin and the binder. . Specific examples of such a high boiling point solvent are dimethyl sulfoxide, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol, triethylene glycol monomethyl ether, triethylene glycol, ethylene glycol monophenyl ether, and phosphoric acid. Trimethyl, triethyl phosphate, ethylene carbonate, trioxane, γ-butyrolactone, γ-valerolactone, diacetone alcohol, methyl acetoacetate, tetrahydrofurfuryl alcohol, dimethylformamide, acetylacetone, cyclohexanone, ethyl lactate, diethylene glycol monoethyl ether acetate, acetic acid Ethylene glycol monomethyl And 2-methyl-2-methoxy-4-pentanone. The amount of these high-boiling solvents added is 2% by weight of the total solvent.
It is as follows. Preferably, it is 0.05 to 1.50% by weight.
When methyl cellosolve is mixed with the coating solvent in the present invention, the highly oil-sensitive polymer compound is less likely to be unevenly distributed on the surface of the photosensitive layer, and the effect of improving the inking property is small. This is because methylcellosolve well dissolves the binder and the polymer compound having high oil sensitivity.

The photosensitive layer of the photosensitive lithographic printing plate used in the present invention may further contain various additives. For example, alkyl ethers (for example, ethylcellulose and methylcellulose), fluorine-based surfactants or silicone-based surfactants for improving coating properties (for example, JP-A-54-135004, JP-A-57-178242, JP-A-57-40248) And plasticizers (for example, tricresyl phosphate, dihexyl phthalate, dioctyl phthalate, trioctyl phosphate, tributyl phosphate, citric acid) for imparting flexibility and abrasion resistance to the coating film. Tributyl acid, polyethylene glycol, polypropylene glycol), and as a coloring substance for visualizing the image area after development, pigments such as acridine dye, cyanine dye, styryl dye, triarylmethane dye and phthalocyanine (for example, Publication No. 56-30859, JP-A-6
No. 3-127235), and general stabilizers for diazo resins (phosphoric acid, phosphorous acid, pyrophosphoric acid, oxalic acid, tartaric acid, malic acid, pyridinedicarboxylic acid, boric acid, benzenesulfonic acid, triene) Sulfonic acid, naphthalenesulfonic acid, alkylnaphthalenesulfonic acid, polyacrylic acid and its copolymer, polyvinylphosphonic acid and its copolymer, polyvinylsulfonic acid and its copolymer, 5-nitronaphthalene-1-phosphonic acid, -Chlorophenoxymethylphosphonic acid, sodium phenyl-
Methyl-pyrazolone sulfonate, 2-phosphonobutanetricarboxylic acid-1,2,4,1-phosphonoethanetricarboxylic acid-1,2,2,1-hydroxyethane-1,1-disulfonic acid). I can do it. The amount of these additives varies depending on the purpose of use, but is generally 0.5 to 30% by weight based on the total solid content of the photosensitive composition.

The photosensitive composition is dissolved in the coating solvent of the present invention and dried on a support having a hydrophilic surface in a dry coating weight of 0.3.
55.0 g / m ² , preferably 0.5-3.5 g / m ²
m ² and dried to obtain a photosensitive lithographic printing plate. The solid concentration of the photosensitive composition at the time of coating is suitably from 1.0 to 50% by weight, preferably from 2.0 to 50% by weight.
30% by weight is suitable. As a method for applying the photosensitive composition on the support, a conventionally known method, for example, a method such as roll coating, bar coating, spray coating, curtain coating, and spin coating can be used. The applied photosensitive composition solution is 50 to 1
Drying at 50 ° C. is preferred. As a drying method, drying may be performed at a high temperature after preliminary drying at a low temperature, or may be directly performed at a high temperature.

A support suitable for applying the photosensitive composition of the present invention is a dimensionally stable plate. Such dimensionally stable plate-like objects include those conventionally used as a support for a printing plate. In particular, an aluminum plate is particularly preferable because it is extremely stable in dimensions and inexpensive. Among the aluminum plates, a roughened aluminum plate is more preferable, and this can be manufactured by various methods. For example, wire brush graining, brush graining using a nylon brush while pouring a slurry of abrasive particles, ball graining, chemical graining, electrolytic graining, or compound graining that combines these graining methods Grain the surface. Next, if necessary, anodize by direct current or alternating current electrolysis in sulfuric acid, phosphoric acid, oxalic acid, boric acid, chromic acid, sulfamic acid, or a mixed acid of these to provide a strong passive film on the aluminum surface. Is preferred. The aluminum surface is hydrophilized by such a passivation film itself, but if necessary, the silicate treatment described in US Pat. No. 2,714,066 and US Pat. No. 3,181.461 Sodium silicate, potassium silicate), U.S. Patent No.
2.946,638, potassium fluorozirconate treatment; U.S. Pat. No. 3,201,274, phosphomolybdate treatment; German Patent 1,091,4
No. 33, the polyvinylphosphonic acid treatment described in German Patent No. 1,134,093 and British Patent No. 1,230,447.
No. 6409, phosphinic acid treatment described in U.S. Pat. No. 3,307,951, JP-A-58-16893 and JP-A-58-1829.
Japanese Unexamined Patent Application Publication No. Sho 59-1 / 1992 discloses an undercoating treatment with a complex of a hydrophilic organic polymer and a divalent metal ion described in each publication of JP-A No.
It is particularly preferable to use a water-soluble polymer having a sulfonic acid group which has been subjected to a hydrophilic treatment by undercoating described in JP-A-16551. Other hydrophilic treatment methods include silicate electrodeposition described in US Pat. No. 3,658,662.

A photosensitive lithographic printing plate having a photosensitive composition layer coated and dried on a roughened aluminum plate is exposed to an image and then developed with an alkaline aqueous solution-based developer to produce a negative image with respect to the original image. A relief image is obtained. Light sources suitable for exposure include carbon arc lamps, mercury lamps, xenon lamps, metal halide lamps, strobes, ultraviolet rays, laser beams and the like. The alkaline aqueous solution used for the photosensitive lithographic printing plate is pH =
It is contained in an amount of from 8 to 13% by weight of water and at least 75% by weight. If necessary, a small amount of an organic solvent, a surfactant, an alkali agent, an antifouling agent, a water softener and the like can be added. For example, Japanese Patent Application Laid-Open Nos. 51-77401, 51-80228, and 5
An organic solvent having a solubility in water of 10% by weight or less at room temperature (such as benzyl alcohol and ethylene glycol monophenyl ether) as described in JP-A-3-44202 and JP-A-55-52054. ,
Alkaline agent (triethanolamine, diethanolamine, monoethanolamine, sodium phosphate, sodium carbonate, etc.), anionic surfactant (aromatic sulfonate, dialkyl sulfosuccinate, alkylnaphthalene sulfonate, fatty acid salt, alkyl sulfate) Salts), nonionic surfactants (polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene polyoxypropylene block polymer, etc.), water and, if necessary, antifouling agents (sodium sulfite, sodium salt of sulfopyrazolone, etc.) ) And a water softener (e.g., tetrasodium ethylenediaminetetraacetate, trisodium nitrilotriacetate) are mixed and dissolved in a weak alkaline aqueous solution. The photosensitive lithographic printing plate of the present invention is disclosed in JP-A-54-800.
No. 2, No. 55-115045, JP-A-59-5843.
Needless to say, the plate-making process may be performed by the method described in each of the publications. That is, after the development processing, it may be subjected to a desensitization treatment after washing with water, a desensitization treatment as it is, a treatment with an aqueous solution containing an acid, or a desensitization treatment after treating with an aqueous solution containing an acid. Furthermore, in the development process of this type of photosensitive lithographic printing plate, the alkali aqueous solution is consumed depending on the processing amount, and the alkali concentration is reduced, or the alkali concentration is reduced by air due to long-time operation of the automatic developing solution. Processing capacity decreases,
The processing ability may be restored by adding a fresh unused developer (replenisher) or using a highly alkaline replenisher as described in JP-A-54-62004. In this case, it is preferable to replenish by a method of adding a replenisher in an amount proportional to the length of one piece of the PS plate to be processed or a method described in U.S. Pat. No. 4,882,246. The plate making process described above is described in JP-A-2-7054 and JP-A-2-323.
It is preferably carried out with an automatic developing machine as described in JP-A-57-57. In addition, as the desensitized gum applied as desired in the final step of the plate making process, Japanese Patent Publication No. Sho 62-16
No. 834, No. 62-25118, No. 63-52600
No., JP-A-62-7595, JP-A-62-11693,
What is described in each gazette of the said 62-83194 is preferable.

[0015]

The photosensitive lithographic printing plate of the present invention is alkali developable and has high oil sensitivity. Therefore, the ink deposition property at the time of printing in printing is good.

[0016]

Next, the present invention will be described by way of examples. Example 1 An aluminum plate was immersed in an aqueous sodium phosphate solution and degreased.
After polishing with a brush, electrolytic etching was performed, followed by anodic oxidation in sulfuric acid, and further immersion in an aqueous solution of sodium silicate for hydrophilic treatment. The following photosensitive composition was dissolved in the following solvent on the hydrophilized aluminum plate, applied with a Wheeler coater, and dried in a 100 ° C. oven for 80 seconds to obtain a photosensitive lithographic printing plate. The coating amount after drying is 1.
It was 5 g / m ² . Photosensitive composition Binder-1 5.00 g Diazo resin-1 0.50 g Stylite HS-2 (manufactured by Daido Kogyo Co., Ltd.) 0.10 g Victoria Pure Blue BOH 0.15 g Tricresyl phosphate 0.50 g Malic acid 0 .10 g Phosphorous acid 0.10 g FC-430 (surfactant manufactured by 3M) 0.05 g Solvent 1-methoxy-2-propanol 25.00 g Methyl lactate 12.00 g Methanol 30.00 g Methyl ethyl ketone 30.00 g Water 3.00 g

Binder-1 is 2-hydroxyethyl methacrylate / acrylonitrile / methyl methacrylate / methacrylic acid copolymer (weight ratio 50/20/26/4,
It is a water-insoluble, alkaline water-soluble film-forming polymer having a weight average molecular weight of 75,000 and an acid content of 0.4 meq / g). Diazo resin-1 is a hexafluorophosphate salt of a condensate of p-diazodiphenylamine and paraformaldehyde described in Synthesis Example 1 of JP-A-59-78340. Stylite HS-2 (manufactured by Daido Kogyo Co., Ltd.) is a polymer compound having a higher oil sensitivity than a binder (hereinafter referred to as an oil sensitizer), and comprises styrene / mono-4-methyl-2-maleate. It was a copolymer of pentyl ester = 50/50 (molar ratio), and the weight average molecular weight was about 100,000. The photosensitive lithographic printing plate is image-exposed and 800H (Fuji Photo Film Co., Ltd. automatic developing machine), DN-3C
(Fuji Photo Film Co., Ltd. alkaline aqueous solution developer)
Is developed with a solution diluted 1: 1 with water.
(Gum solution manufactured by Fuji Photo Film Co., Ltd.) diluted 1: 1 with water was applied and dried. The next day, this printing plate was used for Harris Aurelia printing press (manufactured by Harris Corporation), 6.0
When printing was performed at a speed of 00 sheets / hour, a printed matter having a sufficient ink density was obtained on the sixth printing sheet. (The following Examples and Comparative Examples are referred to as the sixth inking property, etc.)

Examples 2 to 7 Table 1 shows the inking properties when various diazo resins, binders and sensitizers were used using the solvent of Example-1.

[Table 1] 例 Example Binder Diazo resin Desensitizing agent Meatability ─── ─────────────────────────── 2-1 -1 -2 6th sheet ───────────── ３ 3-1 -1 -3 6th sheet ─────────────────────── ４ 4-1 -1 -4 6th sheet ────────────────────────────── 5-1 -1 -5 6th sheet ６ 6 -2 -1 -1 6th sheet ─── ７ 7-1-2 -1-6th sheet ───────────── ────────────── ───

The sensitizer-2 is a copolymer of styrene / maleic acid mono-n-hexyl ester = 50/50 (molar ratio), and has a weight average molecular weight of about 200,000.
The sensitizer-3 is a copolymer of styrene / mono-2-ethyl-maleic acid-hexyl maleate = 65/35 (molar ratio), and has a weight average molecular weight of about 90000. The sensitizer-4 is methyl vinyl ether / maleic acid mono-
2-ethyl-hexyl ester = 50/50 (molar ratio)
And the weight average molecular weight is 90000. The sensitizer-5 is styrene / maleic acid mono-n-hexyl ester / maleic acid di-n-propyl ester /
It is a copolymer of maleic anhydride = 50/30/10/10 (molar ratio), and has a weight average molecular weight of about 100,000. Binder-2 is 2-hydroxyethyl methacrylate / acrylonitrile / ethyl methacrylate / methacrylic acid copolymer (weight ratio 45/15/36/4, weight average molecular weight 120000, acid content 0.4 meq / g). Diazo resin-2 is an n-dodecylbenzene sulfonate of a condensate of p-diazodiphenylamine and formaldehyde.

Examples 7 to 17 Table 2 shows the inking property of the diazo resin, binder and sensitizer of Example 1 when various solvents were used.

[Table 2] Comparative Examples 1 to 10 Table 3 shows the inking property when the binder and the diazo resin of Example 1 were used, the sensitizer was omitted, and when a solution composition other than the present invention was used.

[Table 3] As is apparent from the above examples, it can be understood that the photosensitive lithographic printing plate manufactured according to the present invention has excellent inking property.

Claims (1)

(57) [Claims] 1. A negative photosensitive composition containing a diazo resin, a binder and a copolymer having a structural unit represented by the following general formula: (a) 1-methoxy-2-propanol: 5 to 40% by weight % (B) Methyl lactate: A method for producing a photosensitive lithographic printing plate, comprising dissolving in a coating solvent containing 2 to 20% by weight, applying the solution to a support having a hydrophilic surface, and drying. Embedded image R ¹ represents a methyl group, an ethyl group, a methoxy group, an ethoxy group or an aryl group. R ² and R ^{3 each} have 2 to 20 carbon atoms.
Represents an alkyl group or an aryl group. R ² and R ³ may be the same or different. The ratio of A is 20 to 8 in molar ratio.
The range is 0%. The ratio of B is in the range of 20 to 80% by molar ratio. The ratio of C is in the range of 0 to 20% in molar ratio. The ratio of D ranges from 0 to 20% by mole.