JPH035754A - Production of planographic printing plate - Google Patents

Abstract

PURPOSE:To allow development with an aq. soln. contg. silicate of high pH without generating the sludge of a photocrosslinkable polymer by forming the above-mentioned polymer of a specific polymer which is soluble or swellable in alkaline water. CONSTITUTION:The acid value of the photocrosslinkable polymer is confined to 50 to 200, the weight average mol. wt. thereof to 5,000 to 100,000 and the glass transition temp. to <=50 deg.C in the case of developing the photosensitive planographic printing plate having a negative type photosensitive layer contg. the photocrosslinkable polymer and sensitizer on a base with the aq. soln. which contains substantially no org. solvent and contains the silicate of >= pH 12. The development is executed without generating the sludge in this way even if the printing plate is developed repeatedly by the developer consisting of the aq. silicate soln. of the high pH. The processing of the planographic printing plates of both negative and positive types by using one kind of the developer and one unit of automatic developing machine is, therefore, possible.

Description

[Detailed Description of the Invention] [Field of application in industry] The present invention relates to a method for producing a lithographic printing plate from a photosensitive lithographic printing plate, and in particular, the present invention relates to a method for producing a lithographic printing plate from a photosensitive lithographic printing plate, and in particular, the present invention relates to a method for producing a lithographic printing plate from a photosensitive lithographic printing plate. This invention relates to a method for producing a lithographic printing plate developed with an aqueous solution.

[Prior art and problems to be solved] There are two types of photosensitive lithographic printing plates: negative and positive. When developing each printing plate, a dedicated developer is required for each. It is common to use Therefore, when these two types of photosensitive lithographic printing plates are used at the same time, two types of developing solutions are required. Further, when developing a large number of two types of lithographic printing plates, two automatic developing machines or the like are required, which poses economical problems such as installation costs and installation area.

In addition, when processing both types of photosensitive planographic printing plates in common with one automatic processor, the developer must be replaced each time depending on the type of photosensitive planographic printing plate being processed. This was extremely wasteful in terms of work efficiency and economy.

In order to solve this problem, a method has been proposed in which both photosensitive lithographic printing plates are developed with the same developer;
The reality is that good results have not yet been obtained. The following may be the reason for this. In other words, for boat fishing, the developer for a positive-working lithographic printing plate, which has a photosensitive layer made of an 0-quinonediazide compound and an alkali-soluble resin, is mainly composed of alkaline water with a pH of 12 or more containing silicate as a main component. When this developer is used to develop the unexposed areas of a negative planographic printing plate made of a water-insoluble diazo resin and an alkali-soluble resin, it may not be developed at all, or
Alternatively, there is a problem that residual development is likely to occur, and stains are likely to occur during printing. On the other hand, when developing the exposed areas of a positive planographic printing plate with a developer for a negative planographic printing plate, the development is not done well and a residual film remains.
In some types of negative developing solutions, the photosensitive layer of the positive planographic printing plate is easily soaked by the solvent contained in the negative developing solution.
This has caused problems such as narrow development tolerance and reduced oil sensitivity and stiffness resistance.

In order to solve the above problem, Japanese Patent Application Laid-Open No. 64-56442
The specification discloses a method of developing a photosensitive lithographic printing plate having a photosensitive layer made of an alkali-soluble polymer, a monomer, and a photopolymerization initiator using a developer for positive-working photosensitive printing plates.

However, the chlorine contained in this photosensitive layer is not substantially dissolved in the alkaline developer, and as the amount of printing plates processed increases, undissolved content remains in the developer, which blocks oxygen. Coupled with the overcoat layer such as polyvinyl alcohol provided to prevent this from dissolving in the developer, as the throughput of printing plates increases, the viscosity of the developer increases significantly, causing problems such as a decline in development processing ability. It was a dot.

By the way, as a photocrosslinkable polymer, JP-A-52-988
In the specification of Japanese Patent Publication No. 60-37123, a polymer having a dimethylmaleimide group is disclosed in JP-A No. 60-1912.
In the specification of No. 44, photosensitive polymers having in the main chain are disclosed in JP-A-62-175729, JP-A-62-175730, JP-A-63-25443, and JP-A-63-21894.
No. 4 and JP-A-63-218945 each describe a photosensitive polymer having a photodimerizable functional group such as silicic acid and a carboxyl group in the side chain.

However, photosensitive lithographic printing plates using these polymers are mostly developed using a developer containing an organic solvent. When developed with a developer containing an acid salt, generally, as with the case of the negative planographic printing plate made of the above-mentioned diazo resin and alkaline water-soluble resin, the developability is markedly reduced and development remains are likely to occur. It was considered. In particular, when processing a large number of printing plates by replenishing the developer containing high pH silicate, which is used as a developing method for positive planographic printing plates, and adjusting the ρtla of the solution. However, as the concentration of silicate in the developer increases and the number of printed plates increases, problems arise, such as the formation of polymer sludge, which is thought to be due to salting out.

Therefore, an object of the present invention is to provide a method for producing a lithographic printing plate in which a negative-working photosensitive lithographic printing plate having a photocrosslinkable polymer can be developed with an aqueous solution containing a silicate having a pH of 12 or higher and containing substantially no organic solvent. It is about providing.

[Means to solve the problem]

As a result of intensive studies to achieve the above object, the present inventors have developed a photosensitive lithographic printing plate having a negative photosensitive layer containing a photocrosslinkable polymer and a sensitizer on a support, substantially free of organic solvents. ρ) When developing with an aqueous solution containing a silicate of 112 or more, the acid value of the photocrosslinkable polymer is 50 to 200.
, by setting the weight average molecular weight to 50,000 to 100,000 and the glass transition temperature to 50°C or less, high pH silicon M
It has been discovered that development can be carried out without generating sludge even if the development is repeated with a developer consisting of an aqueous salt solution, and the present invention has been achieved based on this knowledge.

The present invention will be explained in detail below.

The photocrosslinkable polymer used in the present invention is a polymer having a maleimide group, cinnamyl group, cinnamoyl group, cinnamylidene group, cinnamylidene acetyl group, chalcone group, etc. in its side chain or main chain, which causes a photodimerization type reaction. ,
Polymers having maleimide groups in their side chains are preferred because of their high sensitivity.

As a polymer having a maleimide group in a side chain, JP-A No. 52-988 (corresponding U.S. Pat. No. 4.079.041)
Specifications, strong country patent 2.626.769 specification, European patent 21.019 specification, European patent 3.
No. 552 specification and Die Angewandte M
11
5 (1983) on pages 163-181: and R+ may be taken together to form a 5- or 6-membered carbon ring.

) Polymers having maleimide groups in their side chains,
JP 49-128991, JP 49-128992, JP 49-128993, JP 50-5376, JP 5
No. 0-5377, No. 50-5379, No. 50-537
No. 8, No. 50-5380, No. 53-5298, No. 5
No. 3-5299, No. 53-5300, No. 50-501
No. 07, No. 51-47940, No. 52-1390? No. 50-45076, No. 52-121700, No. 50-10884, No. 50-45087, and German Patent Nos. 2.349.948 and 2.616.276. The following - formation (■): (wherein,
R3 represents an aromatic group, and R3 represents a hydrogen atom, a halogen atom, an alkyl group, or a cyano group.

In order to make these polymers soluble or swellable in alkaline water, suitable acid groups are introduced into the polymers. Specific examples of acid groups include carboxylic acids, sulfonic acids, phosphoric acids, phosphonic acids, alkali metal salts and ammonium salts thereof, and acid groups having a dissociation constant pKa of 6 to 12 with respect to alkaline water. is -3O2Nl(CO--CONI
(CO--3O2N)ICUO-The preferred amount of acid groups is
The acid value is in the range of 50 to 200, preferably 50
~150.

If the acid value is less than 50, it will not be solubilized in alkaline water containing silicate, and if it is more than 200, the film strength during and after development will be weakened, resulting in a satisfactory printing plate. I can't get it.

A preferred acid group in the present invention is a carboxylic acid, and a polymer having this is generally a photocrosslinkable polymer with a vinyl monomer having a carboxyl group such as acrylic acid or methacrylic acid, or a monomer such as maleic anhydride or itaconic anhydride. Obtained by copolymerization with monomers having groups.

Furthermore, in synthesizing this copolymer, a multicomponent copolymer suitable for the purpose of the present invention can be easily synthesized by copolymerizing a third component, a nohinyl monomer. For example, the third component vinyl monomer may be an alkyl methacrylate or alkyl acrylate whose homopolymer has a glass transition point below room temperature, and the third component vinyl monomer represented by the following formula (III) may be used to improve alkali solubility and flexibility. It is possible to give sex.

It is necessary that the glass transition temperature of the photocrosslinkable polymer is 50°C or less, and if the glass transition temperature is higher than this,
During development, the speed becomes extremely slow and satisfactory developability cannot be obtained. This is thought to be due to the slow penetration of development into the photosensitive layer.

The weight average molecular weight of these polymers is 50,000 to 100,000, more preferably 10,000 to 50,000 in terms of GPC polystyrene. If the molecular weight is too small, the sensitivity will be low and the image area will become extremely weak during development, while if the molecular weight is too high, the developability will be poor.

Among these polymers are
Macromolecule Chemie (DieAngewand)
Te! Jakromolekulare Chern
A copolymer of N-[2-(methacryloyloxy)ethyl]-2,3-dimethylmaleimide and methacrylic acid or acrylic acid as described on pages 71 to 91 of IE) I 28 (1984), with an acid value 5
0 to 100, a weight average molecular weight of 1,000,000 to 5,000,000, and a glass transition temperature of 20 to 40°C, and a polymer having a cinnamoyl group in a side chain adjusted to a suitable range of the present invention is also preferable. Specifically, it is obtained by a combination of repeating units as shown in (a) to (C) below.

426- The amount of the above polymer added to the total composition in the photosensitive layer is 1
0 to 99% by weight, preferably 50 to 99% by weight.

The sensitizer used in the present invention is preferably a triple stack sensitizer having a maximum absorption that actually allows sufficient light absorption in the range of 300 nm or more. Such sensitizers include benzophenone derivatives, benzanthrone derivatives, quinones, aromatic nitro compounds, naphthothiazoline derivatives, benzothiazoline derivatives, thioxanthones, naphthothiazole derivatives, ketocoumarin compounds, benzothiazole derivatives, naphs, and tofuranone compounds. , pyrylium salt,
Thiapyrylium salt and the like can be mentioned. Specifically, Michler's ketone, N,N'-diethylaminohensiphenone, benzanthrone, (3-methyl-1,3-cyaz-1,9-benz)anthrone biclamide, 5-nitroacenaphthene, 2-chlor Thioxanthone, 2-isopropylthioxanthone, dimethylthioxanthone,
Methylthioxanthone-1-ethylcarboxylate,
2-nitrofluorene, 2-dibenzoylmethylene-3
-Methylnaphthothiazoline, 3,3-carbonyl-bis(7-dinithylaminocoumarin), 2゜4.6-)liphenylthiapyrylium perchlorate, 2-(P-chlorobenzoyl)naphthothiazole, etc. I can do it.

Furthermore, in order to solubilize these sensitizers in alkaline water,
An initiator into which an ionic group is introduced and an initiator into which ethylene oxide is introduced are also desirable.

The amount of the sensitizer added is about 1 to about 20% by weight, preferably 3 to 10% by weight of the total composition in the photosensitive layer.

The negative photosensitive layer of the present invention may contain a binder, if necessary, and is usually appropriately selected from linear organic polymers. Specific examples of binders include chlorinated polyethylene, chlorinated polypropylene, polyacrylic acid alkyl ester,
Copolymers of acrylic acid alkyl esters and at least one of the following, such as acrylonitrile vinyl chloride, styrene, butadiene, polyamides, methyl cellulose,
Examples include polyvinyl formal, polyvinyl butyral, methacrylic acid copolymers, acrylic acid copolymers, itaconic acid copolymers, and the like.

Furthermore, it is also preferable to add a diazo resin to the photosensitive layer of the present invention, and an alkali-soluble diazo resin is particularly preferable. For example, a diazo resin having the following structural unit (rV) can be mentioned.

Indicates a roxy group.

, R7 represents a carboxyl group or a group having at least one carboxyl group, preferably a carboxyl group or a group having at least one carboxyl group and having a carbon number of 1
Indicates a group of 5 or less.

R1 represents a hydrogen atom, an alkyl group or an alkoxy group,
Preferably it represents a hydrogen atom or an alkoxy group having 1 to 3 carbon atoms.

R4 represents a hydrogen atom, an alkyl group or an alkoxy group,
Preferably it represents a hydrogen atom or an alkoxy group having 1 to 3 carbon atoms.

X- represents an anion, preferably an anion of an inorganic or organic acid having ρKa of 4 or less.

In the formula, R1 represents a hydrogen atom, an alkyl group that may have a substituent, an alkoxy group, a hydroxy group, a carboxyester group, or a carboxyl group, preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, It is a diazo resin having an alkoxy group having 1 to 3 carbon atoms or a hydrogen structural unit (V).

In some cases, for the purpose of coloring the photosensitive layer, a dye or pigment or a pH indicator as a printing-out agent may be added.

Furthermore, the photosensitive layer of the present invention may contain a plasticizer and the like.

Examples of the plasticizer include phthalic acid dialkyl esters such as dibutyl phthalate and dibutyl phthalate, oligoethylene glycol alkyl esters, and phosphate ester plasticizers.

Furthermore, it is preferable to incorporate a thermal polymerization inhibitor and an antioxidant into the photosensitive layer, such as hydroquinone, p-
Methoxyphenol, di-t-butyl-p-cresol, pyrogallol, L-butylcatechol, benzoquinone, 4.4'-thiobis(3-methyl-6-t-butylphenol), 2.2'-methylenebis(4-methyl −
6-t-butylphenol), 2-mercaptobenzimidazole, and the like are useful.

Examples of compositions for photosensitive layers mainly containing photocrosslinkable polymers and sensitizers include 2-methoxyethanol, 2-methoxyethyl acetate, methyl cellosolve, propylene glycol monomethyl ether, 3-methoxypropanol, and 3-methoxypropanol. Propyl acetate, acetone, methyl ethyl ketone, ethylene dichloride, methyl lactate,
It is coated on a support by dissolving it in a suitable solvent such as ethyl lactate, methanol, dimethylformamide, ethanol, methyl cellosolve acetate, etc. alone or in a mixture thereof. The coverage amount is approximately 0.1 g/m” after drying.
A range of about 10 g/rn' is suitable, preferably 0.
5-5 g/m'.

The developer used in the present invention, which is an aqueous solution containing a silicate with a pH of 12 or more and which is substantially free of organic solvents, includes sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, and trisodium phosphate. , sodium diphosphate, ammonium triphosphate, ammonium diphosphate, sodium metasilicate, sodium bicarbonate,
It is an aqueous solution containing one or more inorganic alkaline agents such as aqueous ammonia, and the concentration thereof is 0.1 to 1.
It is added in an amount of 0% by weight, preferably 0.5 to 5% by weight.

Moreover, a surfactant, a chelating agent, a coloring agent, etc. can also be added to this aqueous solution as necessary.

Further, a small amount of an organic solvent may be added in order to increase the swelling of the photosensitive layer and the wettability of the developer to the photosensitive layer. In the present invention, the expression "substantially free of organic solvent" means that the amount of the used solution is 1% by weight or less, and the amount must be such that it does not adversely affect the positive-working photosensitive lithographic printing plate.

Preferred organic solvents are ethylene glycol,
Benzyl alcohol, 2-phenoxyethanol, 2-
Examples include butoxethanol, n-propyl alcohol, and the like.

Furthermore, nucleophilic compounds and inorganic reducing salt compounds, such as methylresorcinol, pyrazolone compounds, sulfites, and thiosalicylic acid, which are solubilizers for diazo resins, can also be added.

A method for developing a photosensitive lithographic printing plate that has been image-exposed using a developer as described above is a method in which the developer is charged into a developing tank and the photosensitive lithographic printing plate is immersed in the developer and passed through it. , methods that repeatedly use the developer such as spraying the developer in the developer tank, or 1.
A disposable development method in which the amount of developer required to develop a sheet of photosensitive lithographic printing plate is applied to the plate surface, the developer is developed with only the applied developer, and then the developer is discarded and reused. Although various methods are possible, in the present invention, a method in which the developer is repeatedly used is preferable, and in this case, it is preferable to add the developer replenisher continuously or intermittently. The composition of the developer and replenisher in the developing method that performs such replenishment, as well as the replenishment method, are disclosed in Japanese Patent Application Laid-Open No. 54-6200.
No. 4, No. 55-22759, No. 55-115039, No. 56-12645, No. 58-95349, No. 6
No. 4-214.51, Patent Application No. 1983-4560, No. 63
-149617, and can be suitably used in the developing method of the present invention.

The support used in the lithographic printing plate of the present invention is preferably a dimensionally stable plate-like material. Such dimensionally stable plate-like materials include those conventionally used as supports for printed matter, and they can be suitably used in the present invention. Such supports include paper, paper laminated with plastics (eg, polyethylene, polypropylene, polystyrene, etc.), plates of metals such as aluminum (including aluminum alloys), zinc, copper, etc.
Films of plastics such as cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose acetate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.; metals such as those mentioned above are laminated or Includes vapor-deposited paper or plastic film.

Among these supports, aluminum plates are preferred because they are extremely dimensionally stable, inexpensive, and have particularly good adhesion to the composition of the present invention. In addition, the special public
Also preferred are composite sheets in which an aluminum sheet is bonded onto a polyethylene terephthalate film as described in Japanese Patent No. 8-18327.

Further, in the case of a support made of metal, particularly aluminum, it is preferable that the support be subjected to surface treatment such as graining treatment or anodizing treatment.

Further, in order to increase the hydrophilicity of the surface, it is preferable to perform an immersion treatment in an aqueous solution of sodium silicate 1, potassium fluorozirconate, phosphate, or the like.

As described in U.S. Patent No. 2.714.066, an aluminum plate that is grained and then immersed in a sodium silicate aqueous solution, as described in Japanese Patent Publication No. 47-5125, an aluminum plate A material obtained by anodizing and then immersing in an aqueous solution of an alkali metal silicate is also suitably used.

Also effective is silicate electrodeposition as described in US Pat. No. 3,658,662. Also, Japanese Patent Publication No. 46-27481, Japanese Patent Publication No. 52-58602
Also useful is a surface treatment that combines a support coated with electrolytic grains with the above-mentioned anodic oxidation treatment and sodium silicate treatment as disclosed in Japanese Patent Application Laid-Open No. 52-30503.

Furthermore, it is also suitable to perform brassiderein treatment, electrolytic grain treatment, anodization treatment, and further sodium silicate treatment in this order, as disclosed in JP-A-56-28893. Further, after these treatments, it is also suitable to apply an undercoat with a water-soluble resin such as polyvinylphosphonic acid, a polymer or copolymer having a sulfonic acid group in a side chain, polyacrylic acid, or the like. Also suitable are those coated with a diazo resin.

These hydrophilic treatments are performed not only to make the surface of the support hydrophilic, but also to prevent harmful reactions with the photosensitive composition provided thereon, and to improve the adhesion with the photosensitive layer. This is done for the purpose of improving the quality of life.

Image exposure is carried out by using a light-sensitive lithographic printing plate with an ultraviolet-rich light source such as a metal halide lamp, high-pressure mercury lamp, etc., and then treated with a developer as described above to remove the unexposed areas of the photosensitive layer. Finally, a lithographic printing plate is prepared by applying a gum liquid.

〔Effect of the invention〕

According to the present invention, by developing a negative photosensitive lithographic printing plate with an aqueous silicate alkaline solution that does not substantially contain an organic solvent, a lithographic printing plate can be obtained without producing scum, sludge, or the like. That is, a negative-working planographic printing plate can be manufactured by the same process as a conventional positive-working photosensitive planographic printing plate. Therefore, it is possible to process both negative and positive planographic printing plates using one type of developer and one automatic processor.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to these Examples.

Example 1 The surface of an aluminum plate with a thickness of 0.30 + nm was grained using a nylon brush and a 400 mesh water suspension of pumice stone, and then thoroughly washed with water.

After etching by immersing in IJum (10% hydroxide) at 70° C. for 60 seconds: Washing with running water, neutralization washing with 20% HNO3, and washing with water. This was applied to a 16% nitric acid solution in a 1% nitric acid aqueous solution using a sinusoidal alternating current waveform under the condition of VA=12.7V.
Electrolytic surface roughening treatment was performed with an anode special electricity amount of 0 coulomb/d+r+2. When the surface roughness was measured, it was found to be 0.6μ
(Ra display). followed by 30% It, SO
, immersed in an aqueous solution and desmutted for 2 minutes at 55°C, 20% H, PO, current density 2A/dm in an aqueous solution.
Anodizing was carried out for 2 minutes so that the thickness became 1.5 g/m'. Next, 2.5% sodium silicate at 70℃
After being immersed in an aqueous solution for 1 minute, washed with water, and dried, the following photosensitive composition ■: Photosensitive composition I: 0 methyl methacrylate/N-[:2-(methacryloyloxy)ethyl]-2.3-dimethyl Maleimide/
Methacrylic acid = 10/60/30 (mole ratio) copolymer [:Mw = 1.5 x 10' (GPC) 7g = approximately 40°C (DSC)] 5g 0 Sensitizer represented by the following structural formula 0 Propylene Glycol monomethyl ether 0g o Methyl ethyl ketone 50g 0 Megafac F-177 (manufactured by Dainippon Ink, fluorine-based nonionic surfactant) 0.03go 10% plasticizer dispersion of steel phthalocyanine pigment (CI Pigment Blue 15) 1. Og was applied onto the above support using a spin coater to give a weight of 1.5 after drying.
g/m' and then dried at 80° C. for 2 minutes to produce a negative photosensitive lithographic printing plate.

The thus obtained negative photosensitive lithographic printing plate was subjected to contact exposure through a negative film step wedge (density difference 0.15, number of density steps 15). Exposure was performed by irradiating with a 2 μW ultra-high pressure mercury lamp for 60 seconds.

Next, it was developed with a 3% aqueous sodium silicate solution (pH=about 13) at 25° C. for 30 seconds. After washing with water, apply gum solution.
When printed with an ORD printing machine, 50,000 prints with no stains in the non-image areas were obtained. On the other hand, with this developer,
4 ml of the above negative photosensitive lithographic printing plate per developer 11
However, no scum or sludge was found.

For comparison, commercially available negative PS plates FNS (manufactured by Fuji Film ■), S'vVN (manufactured by Konica), and U
When NL-N (manufactured by Kaihon Kagaku) was exposed and developed under the same conditions as in Example 1, development was not possible with FNS and UNL-N. Further, although S'vVN was apparently able to be developed, the non-image area received ink during printing and became smudged, so that no printed matter could be obtained.

Example 2 After electrolytically roughening the support of Example 1, it was subsequently immersed in a 30% H2SO aqueous solution and heated at 55°C for 2 hours.
Desmut for minutes, then 20% H2SO.

Anodizing was carried out for 5 minutes in an aqueous solution at a current density of 2 A/dm' so that the amount of anodized film was 2.0 g/m''.
After soaking for a minute, washing with water, and drying, the following photosensitive composition ■: Photosensitive composition ■: oN-[2-(meta-2,3-dimeric acid = 65/3 (Mw = 1.4) X 1 0 Sensitizer below Chryloyloxyethyl] Tilmaleimide/methacrylic 5 (mole ratio) copolymer 0', Tg=36°C) 5g 0.3g 0 Propylene glycoyl monomethyl ether 0g O Methyl ethyl ketone 50g 0 Megaph 7' /ri F-1770,03go oil blue #6
03 (To Orient Chemical Industry Co., Ltd., K) 0゜15g Coated onto the support using a spin coating machine so that the weight after drying was 1.5g/rn'', and then dried at 80℃ for 2 minutes. A photosensitive lithographic printing plate was produced.

Next, in the same manner as in Example 1, this negative photosensitive lithographic printing plate was exposed to light and developed for 40 seconds at 25° C. using an automatic developing machine (manufactured by Fuji Film Co., Ltd., PS800E) using the following developer.

Developer: oJIS No. 3 Sodium Silicate 100go
Potassium hydroxide 50go Surfactant Perex N Roshi (manufactured by Kao Atlas)go Sodium sulfite 5g0Pure water 4000gAfter washing with water, a gum solution was applied to the obtained lithographic printing plate and printing was performed.No stains were found in the non-image areas. 60,000 pieces of printed matter were obtained.

On the other hand, using this automatic developing machine, a commercially available positive photosensitive printing plate (FPS manufactured by Fuji Film) was processed at 2 ms/1.
2 (for developer 11) and the above negative photosensitive lithographic printing plates were processed at 2 m''/l, but there was no stain in the non-image areas of any of the printing plates (and there was no scum or sludge in the developer). No precipitate was observed.

Example 3 On a support treated in the same manner as in Example 2, the following undercoating solution was applied and dried. Application amount is 10mg/m' dry weight
I made it so that

Undercoat liquid: C diazo resin 0.5g m:n=1:1 (mole ratio) 0 methanol 50go pure
100g water
Next, the dry weight of the photosensitive composition I used in Example 1 was 1. A negative photosensitive lithographic printing plate was produced by coating the plate to give a coating film of 0.0 g/m" and drying. Next, in the same manner as in Example 1, this lithographic printing plate was exposed to light, developed, and gummed. A lithographic printing plate was obtained. When this was run on a printing press and printed, 50,000 sheets of clean prints were obtained.

Example 4 Using the support used in Example 2, the following photosensitive composition ■: Photosensitive composition ■: 0 The following polymer 5.0 g 0 The diazo resin having the following structure 0.2 g 0 The sensitizer having the following structural formula O diethyl phthalate 0.4g 0.5g 0 Copper phthalocyanine pigment (CI Pigment Bl
ue 15) 10% plasticizer dispersion 1.
OgoF-177 (Dainippon Ink, K (manufactured by K), fluorine-based nonionic surfactant) 0.02g0 methyl ethyl ketone 20go methanol
Apply 8 g of 2go propylene glycol monomethyl ether onto the support using a spin coater to give a dry weight of 1.
The coating was coated to give a coating density of Og/m' and then dried at 80° C. for 2 minutes to produce a negative photosensitive lithographic printing plate.

In the same manner as in Example 2, this photosensitive planographic printing plate was subjected to exposure, development, and gumming to obtain a planographic printing plate. When this was printed on a printing machine, 40,000 sheets of clean prints were obtained.

As a comparative example, Example 4 was used except that the photosensitive polymer in the photosensitive composition used in Example 4 was changed to the following polymer.
A printed version was obtained in the same manner.

When this printing plate was developed in the same manner as in Example 4, a film remained in the non-image area, and a satisfactory printing plate could not be obtained.

432

Claims (2)

[Claims] (1) A photosensitive lithographic printing plate having a negative photosensitive layer made of a photocrosslinkable polymer and a sensitizer provided on a support contains a silicate with a pH of 12 or more that does not substantially contain an organic solvent after image exposure. In a method for producing a lithographic printing plate comprising removing the photosensitive layer in unexposed areas with a developer, the photocrosslinkable polymer has an acid value of 50 to 200 and a weight average molecular weight of 05,000 to 10.
A method for producing a lithographic printing plate, characterized in that the polymer is an alkali water-soluble or swellable polymer having a glass transition temperature of 50° C. or less. (2) The method for producing a lithographic printing plate according to claim (1), wherein a replenisher is continuously or intermittently added to the developer containing a silicate having a pH of 12 or higher and substantially free of organic solvents.