JPH03213862A - Developing solution for original plate for waterless planographic printing plate - Google Patents

Abstract

PURPOSE:To obviate the degradation in the adhesiveness between the photosensitive layer of a non-image part and a silicone rubber layer and to improve the reproducibility in the shadow part of dots by developing the photosetting photosensitive layer contg. a specific binder polymer by using the developing soln. consisting of a silicate and water. CONSTITUTION:The developing soln. for the original plate for a waterless planographic printing plate successively having a primer layer, the photosetting photosensitive layer contg. a binder polymer having 10 to 300 acid value and a silicone rubber layer on a base consists substantially of the silicate and the water and the conc. of the SiO2 of the silicate is specified to a 0.5 to 6wt.% range. The reason for limiting the SiO2 of the silicate to the 0.5wt./ to 6wt.% range lies in that the effect of the halftone reproducibility does not appear if the concn. is below 0.5wt.% and the halftone reproducibility is inferior if the concn. exceeds 6wt.% and that such is undesirable. The degradation in the adhesiveness between the photosensitive layer of the non-image part and the silicone rubber layer is prevented in this way and the reproducibility of the shadow part of the dots is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer for a waterless lithographic printing plate precursor, and more specifically to adhesiveness between a photosensitive layer in a non-image area and a silicone rubber layer. This invention relates to a developing solution for a waterless lithographic printing plate precursor that does not cause a decrease in surface area and has excellent reproducibility of part of the shadow.

[Background of the Invention] Various types of waterless lithographic printing plate precursors have been known, including those having a structure in which a photosensitive layer and an ink repellent layer are sequentially coated on a support.

This waterless lithographic printing plate precursor is imagewise exposed and then developed, and the developer used for this is conventionally known to use a hydrocarbon-based organic solvent such as Isopar H or toluene. However, when these hydrocarbon-based organic solvents are used as developers for waterless lithographic printing plate precursors, there are safety and hygiene problems, so in recent years water-based developers have been used instead. Many technologies have come into use. For example, JP-A-1-257847 describes a developer for developing a waterless lithographic printing plate precursor, specifically an organic solvent and a basic compound that dissolve or swell the unexposed portions of the photosensitive layer. and an alkaline aqueous developer containing a surfactant.

This developer contains a basic substance to prevent the formation of sludge in the developer, but since the developer containing a basic substance has a high p)l content, waterless lithographic printing is not possible. During development of the printing plate master, the adhesion between the photosensitive layer and the silicone rubber layer decreases in the non-image areas where they are firmly adhered, and the silicone rubber layer peels off from the photosensitive layer, resulting in the reproduction of a portion of the shadow. There was a problem with poor sex.

Therefore, as a result of various studies on the above-mentioned problems, the present inventors have found that by using silicate as an alkaline agent in the developer, the adhesion between the photosensitive layer and the silicone rubber layer can be reduced even at high pH. First, it was possible to obtain an aqueous developer for a waterless lithographic printing plate precursor, which yields a printing plate with good reproducibility of the shadow portion.

[Object of the Invention] Therefore, an object of the present invention is to provide a waterless lithographic printing plate which does not reduce the adhesion between the photosensitive layer and the silicone rubber layer in the non-image area and which has excellent reproducibility of part of the shadow of halftone dots. Our objective is to provide a developing solution for original plates.

[Constitution of the Invention] The object of the present invention is to provide a primer layer on a support with an acid value of 1.
A developer for a waterless lithographic printing plate precursor having a photocurable photosensitive layer containing a binder polymer of 0 to 300% and a silicone rubber layer in sequence, wherein the developer consists essentially of a silicate and water, and the developer contains a silicate. This was achieved using a developer solution for a waterless lithographic printing plate precursor, characterized in that the 5i02 concentration is in the range of 0.5 to 6% by weight.

The present invention will be specifically explained below.

The developer of the present invention is used to develop a waterless lithographic printing plate precursor containing a photocurable photosensitive layer containing a binder polymer having an acid value of 10 to 300, and the developer contains substantially water and a silicate salt. In particular, the 5in2 concentration of silicate is 0.5
% to 6% by weight, preferably 5% by weight.
The in2 concentration is in the range of 4.0% to 5.0% by weight. Preferred silicates include potassium silicate, sodium silicate, and the like.

The developer of the present invention has a high p)l content, especially p)112~
It is preferable to use 13 or less.

The reason why the 5in2 concentration of silicate was limited to the range of 0.5% to 6% by weight is that if the concentration is less than 0.5% by weight, the effect of halftone dot reproducibility will not appear. Exceeding this is not preferable as halftone reproducibility deteriorates.

The developer of the present invention consists essentially of water and a silicate, or
The toner may contain an organic solvent which is usually added to a developing solution to the extent that it does not cause any problem, and the content thereof is less than 1% by weight.

The photosensitive layer used in the present invention contains a high molecular weight polymer having an acid value of 10 to 300. As the polymer, for example,
Acrylic acid or methacrylic acid copolymers, crotonic acid copolymers, itaconic acid copolymers, maleic acid copolymers, cellulose derivatives having carboxyl groups in their side chains, polyvinyl alcohol conductors having carboxyl groups in their side chains,
Examples include hydroxyalkyl acrylate or methacrylate copolymers having carboxyl groups in side chains, and unsaturated polyester resins having carboxyl groups in side chains.

Among these, preferred is JP-A-55-1553
The copolymer having a phenolic hydroxyl group in the side chain described in JP-A No. 55 and the copolymer having an alcoholic hydroxyl group in the side chain described in JP-A-50-118802, especially dyeability. From the viewpoint of adhesive properties, alcoholic hydroxyl group-containing polymers are preferably used.

Examples of the alcoholic hydroxyl group-containing polymer include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, N-(4-hydroxyethylphenyl)methacrylamide, and hydroxymethyldiacetone (meth)acrylamide.

Preferable results can be obtained when the acid value of the high molecular weight polymer used as the resin binder according to the present invention is in the range of 10 to 300. That is, in an aqueous developer, in order to particularly impart alkaline developability, it is preferable to use a binder resin having an oxidation value of 10 to 300. This allows rapid development speed and provides good images.

Therefore, if the oxidation value is less than 10, the developing speed will be insufficient, and if the oxidation value is more than 300, it will be susceptible to over-development, which is not desirable.

The photosensitive layer used in the present invention includes various diazo resins, but preferably a diazo resin represented by a condensate of p-diazodiphenylamine and formaldehyde, which is water-insoluble and organic solvent-soluble. and preferably Japanese Patent Publication No. 471167 and No. 57-43890.
Those which are water-insoluble and soluble in ordinary organic solvents are used, as described in Japanese Patent Publication No. Particularly preferred is a diazo resin represented by the following general formula [11].

Below is the general formula [1] [where RI R2 and R3 represent a hydrogen atom, an alkyl group, or an alkoxy group, and R4 represents a hydrogen atom, an alkyl group, or a phenyl group.

X represents PF6 or BF4, and Y represents -NH-3- or -0-. ] Examples of the diazo monomer in the diazo resin used in the present invention include 4-diazo-diphenylamine, 1
-Diazo-4-N,N-dimethylaminobenzene, l-
siaci 4- N,N-diethylaminobenzene, 1-
Diazo-4-N-ethyl-N-hydroxyethylaminobenzene, l-diazo-4-N-methyl-N-hydroxyethylaminobenzene, 1-diazo-2,5-jethoxy-4-benzoylaminobenzene, 1- Diazo-4
-N-Benzylaminobenzene, 1-siacy4-N
, N-dimethylaminohensen, l-diazo-4-morpholinobenzene, l-diazo-2,5-dimethoxy-4
-p-Tolylmercaptobenzene, l-diazo-2-ethoxy-4-N, N-dimethylaminobenzene, p-diazodimethylaniline, 1-diazo-2,5-dibutoxy-4-morpholinobenzene, 1- Diazo-2,5-
Jetoxy-4-morpholinobenzene, l-diazo-2
, 5dimethoxy-4-morpholinobenzene, 1-diazo-2,5-jethoxy-4-p-tolylmercaptobenzene, 1-siacy4-N-ethyl-N-hydroxyethylaminobenzene, l-diazo-3-ethoxy -4
-N-methyl-N-benzylaminobenzene,! -Diazo-3-chloro-4- N,N-diethylaminobenzene, 1-diazo-3-methyl-4-pyrrolidinobenzene,
1-diazo2-chloro-4-N,N-dimethylamino-
5-methoxyhensen, 1-diazo-3-methoxy-4
-pyrrolidinohensen, 3-methoxy-4-diazodiphenylamile, 3-ethoxy-4-diazodiphenylamine, 3-(n-propoxy)-4-diazodiphenylamine, 3-(impropoxy)-4-diazo Examples include diphenylamine.

Examples of the aldehyde used as a condensing agent with the diazo monomer include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, and benzaldehyde.

Furthermore, water-soluble diazo resins can be obtained by using chloride ions, tetrachlorozinc acid, etc. as anions, and boron tetrafluoride, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 4.4- biphenyldisulfonic acid, 2,5-dimethylbenzenesulfonic acid, 2
It is possible to obtain an organic solvent-soluble diazo resin by using -nitropensene sulfonic acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, and the like. Particularly preferably, a diazo resin made of hexafluorophosphoric acid is used.

The diazo resin is preferably used in combination with a film-forming resin, particularly a polymer compound having a hydroxyl group. Particularly preferably, the polymer compound is a copolymer of 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate having an aliphatic hydroxyl group in the side chain and other copolymerizable mercury. It will be done.

In addition to these, polyvinyl butyral resins, polyurethane resins, polyamide resins, epoxy resins, novolak resins, natural resins, etc. may be added as necessary.

In addition, various polymeric compounds may be used as the bonding side used in combination with the diazonium salt, and preferably,
Monomers having an aromatic hydroxyl group such as those described in Japanese Patent No. 4-98613, such as N-(4-hydroxyphenyl)acrylamide, N-(4-hydroxyphenyl)methacrylamide, o-, m-, or copolymers of p-hydroxystyrene, o-, m-, or p-hydroxyphenyl methacrylate, etc., with other monomers, such as those described in U.S. Pat. No. 4,123,276. Examples include polymers containing ethyl acrylate units or hydroxyethyl methacrylate units as a main repeating unit.

In addition to these polymers, natural resins such as polyvinyl butyral resin, polyurethane resin, polyamide resin, epoxy resin, novolac resin, shellac, and rosin, polyvinyl alcohol, and U.S. Patent No. 3,751 may be used as necessary.
, polyamide resins described in U.S. Pat. It contains celluloses such as resin, cellulose acetate, and cellulose acetate phthalate.

Examples of the alkali-soluble resin include novolac resin, vinyl polymer having a phenolic hydroxyl group, and JP-A-55-5
Examples include condensation resins of polyhydric phenols and aldehydes or ketones described in Japanese Patent No. 7841. Examples of novolac resins include phenol formaldehyde resin, cresol formaldehyde resin, and JP-A-5
Phenol-cresol-formaldehyde copolycondensation resin as described in JP-A No. 5-57841, p as described in JP-A-55-127553
Examples include copolycondensation resins of -substituted phenol and phenol or cresol and formaldehyde.

The diazo resin used in the present invention is used in combination with a binder resin, and when the binder resin is taken as 100, the diazo resin is preferably in the range of 30 to 200 (weight ratio), preferably 50 to 150, and more preferably 50 to 150. is 70-1
The range is 20.

Other dyes, pigments such as pigments, fat-sensitizing agents, plasticizers, surfactants, etc. can be added to these photosensitive compositions. The amount of these additives added is 0.1% to 20% by weight, preferably 0.1% to 20% by weight in the solid content of the photosensitive layer.
It is used in a range of 5% to 10% by weight.

The silicone rubber used in the present invention is a linear organic polymer having a repeating unit represented by the following general formula [1] and having a molecular weight of several thousand to hundreds of thousands and a hydroxyl group in the main chain or at the end of the main chain. Those containing siloxane as a main component are preferred.

General formula [I] +5i-o% where n is an integer of 2 or more, R is an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, an alkoxyl group, a vinyl group, an aryl group, one silanol group (0) ) and
Preferably, 60% or more of R is a methyl group. The silanol group (or H group) may be located either in the main chain or at the end of the main chain, but is preferably located at the end.

The silane coupling agent (or silicone crosslinking agent) used in the present invention includes Rn5ix4-n (wherein n is an integer of 1 to 3, and R is alkyl, aryl, alkenyl, or a combination thereof). represents a group, and these groups may have a functional group such as halogen, amine, hydroxy, alkoxy, aryloxy, thiol, etc.

2 X is -0H5-CR2, -0Ac, -o-N-c,
Represents a substituent such as -cRl-Br or -In2. Here, 82 and R3 represent the same as R above, and R2 and R3 may be the same or different. Moreover, Ac represents an acetyl group. ) is a silane compound represented by

That is, the silicone rubber useful in the present invention is obtained by a condensation reaction between such a silicone base polymer and a silicone crosslinking agent such as those listed above.

Specific examples of the silane coupling agent used in the present invention include HN[(CL)3si(OMe), ]2, vinyltriethoxysilane, CIl(CH2)3si(OMe),
) s, CH35i (OAc) 3, R5 (CL)
3si (OMe) 3, vinyltris(methylethylketoxime)silane, and the like.

The silicone rubber described above is also available as a commercial product, such as YE-3085 manufactured by Toshiba Silicone Co., Ltd. Other useful silicone rubbers can be obtained by reacting the above-mentioned quick-stitch base polymer with a silicone oil having a repeating unit represented by the following general formula [II], or by reacting a silicone oil with about 3% of R or a vinyl group. It can also be obtained by addition reaction of a certain silicone with a base polymer or by reaction of the silicone oils with each other.

General formula [11] HR (wherein, R has the same meaning as R, which is a substituent of the polymer represented by general formula [II, m is an integer of 2 or more, and n is an integer of 0 or 1 or more.) Ko (7) J: Uftt
In order to obtain silicone rubber by crosslinking reaction, the crosslinking reaction is carried out using a catalyst. As this catalyst, organic carboxylates of metals such as tin, zinc, cobalt, lead, calcium, manganese, etc., such as dibutyltin laurate, tin (!■) octoate, cobalt naphthenate, etc., or chloroauric acid, etc. are used. It will be done.

Further, in order to improve the strength of the silicone rubber and obtain a silicone rubber that can withstand the frictional forces generated during printing operations, fillers can be mixed. Silicone rubber mixed with filler in advance is commercially available as silicone rubber stock or silicone rubber dispersion, and when it is preferable to obtain a silicone rubber film by coating as in the present invention, RTV
Alternatively, dispersion of LTV silicone rubber is preferably used. An example of this is syt Off 23.5RX-257,5H manufactured by Toray Silicone.
There are silicone rubber dispersions for vapor coating such as 237.

In the present invention, it is preferable to use condensation and crosslinking type silicone rubber.

The silicone rubber layer preferably contains a silane coupling agent having an amino group in order to further improve adhesiveness.

Examples of preferable silane coupling agents include the following.

(a) H2NCH2CH2NH ((:R2) 3si
(OCH3) 3(b) 82NCE2C)12NH
(C)12) 3si (0(:)1312 (CH3
)(c) H2N (CH2) 3si (OEj)
3. The silicone rubber layer used in the present invention may further contain a small amount of photosensitizer.

The silicone rubber layer used in the present invention is prepared by dissolving silicone rubber in a suitable solvent, applying it onto the photosensitive layer, and drying it.

The support of the present invention is preferably one that is flexible enough to be set in a normal lithographic printing machine and that can withstand the load applied during printing, such as metal plates such as aluminum, zinc, copper, and steel, and metal plates such as chromium, zinc, Examples include metal plates plated or vapor-deposited with copper, nickel, aluminum, iron, etc., paper, plastic films, glass plates, resin-coated paper, paper covered with metal foil such as aluminum, and the like.

Among these, aluminum plates are preferred.

The treatment of the support itself to improve the adhesion is not particularly limited, and includes various surface roughening treatments.

The support may have a primer layer, and the primer layer may include, for example, polyester resin, vinyl chloride-vinyl acetate copolymer, acrylic resin, vinyl chloride resin, polyamide resin, polyvinyl butyral resin, epoxy resin, acrylate. Examples include polyvinyl acetate copolymers, vinyl acetate copolymers, phenoxy resins, polyurethane resins, polycarbonate resins, polyacrylonitrile butadiene, and polyvinyl acetate. A compound that generates an acid upon exposure to light and a dye that changes color or fades due to the acid can be added to these primer layers.

In addition, as the anchor agent constituting the primer layer,
For example, the aforementioned silane coupling agents, silicone primers, etc. can be used, and organic titanates and the like are also effective.

The thickness of each layer constituting the plate material of the present invention is as follows. That is, the support has a thickness of 50 to 400 μm, preferably 100 μm.
~300μm, photosensitive layer 0.05~10μm, preferably 0.5~5μ11 silicone rubber layer 0.1~1Oμm
m1 is preferably 0.5 to 2 μm.

In the present invention, a protective layer may be provided on the upper surface of the silicone rubber layer, if necessary.

[Examples] The present invention will be explained below with reference to Examples, but the present invention is not limited thereto.

Example 1 [Manufacture of aluminum plate a] An aluminum plate with a thickness of 0.2 mm was degreased by immersing it in a 3% aqueous sodium hydroxide solution, washed with water, and then immersed in an aqueous solution with a hydrochloric acid concentration of 1 part and a boric acid concentration of 1%. Inside, the temperature is 25℃
Electrolytic etching was performed for 5 minutes at 3 A/dm2.
After washing with water, 1.
Anodize for 2 minutes at 5A/dm2, wash with water,
It was immersed in a 1% aqueous sodium metasilicate solution at a temperature of 85°C for 37 seconds, and then immersed in water (p) 18.5) at a temperature of 90°C for 25 seconds.
It was immersed for seconds, washed with water, and dried to obtain an aluminum plate a.

A photosensitive composition having the composition shown below was applied to an aluminum plate a, and dried at 100° C. for 2 minutes to form a photosensitive layer having a thickness of 0.5 μm.

[Photosensitive composition (1) Diazo resin - 165 parts (2) Molar ratio of 2-hydroxyethyl methacrylate, acrylonitrile, methyl methacrylate, ethyl acrylate, and acrylic acid is 55/10/10.15/20 Copolymer 35 parts (3) Victoria Pure Blue BOH (dye manufactured by Hodogaya Chemical Co., Ltd.) 1 part (4) Methyl cellosolve 900 parts Synthesis of diazo resin-1 Diazo resin-1 was synthesized as follows. .

14.5 g (50 mmol) of p-diazodiphenylamine sulfate was dissolved in 40.9 g of concentrated sulfuric acid under water cooling. To this reaction solution, 1.35 (45 mmol) of paraformaldehyde was slowly added so that the reaction temperature did not exceed 10°C.

This reaction mixture was added dropwise to 500 ml of ethanol under water cooling, and the resulting precipitate was filtered. After washing with ethanol, this precipitate was dissolved in 100 ml of pure water, and 6.8
A cold concentrated aqueous solution of 1 g of zinc chloride was added. After filtering the resulting precipitate, it was washed with ethanol, and then washed with 150
Dissolved in ml pure water. To this liquid was added a cold concentrated aqueous solution in which 8 g of ammonium hexafluorophosphate was dissolved. The formed precipitate is collected by filtration, washed with water, and dried to form a diazo resin.
I got 1.

Next, the following silicone rubber composition was applied onto the photosensitive layer at a dry weight of 1.5 g/m2.
It was dried at ℃ for 10 minutes to obtain a lithographic printing plate material that did not require dampening water.

[Silicone rubber layer composition] Dimethylpolysiloxane having hydroxyl groups at both ends (molecular weight 52,000) 100 parts Triacetoxymethylsilane 10 parts Dibutyltin laurate 0.8 parts Isopar G (manufactured by Esso Chemical) 900 parts of the above plate material After a positive film was vacuum-adhered to the top surface, exposure was performed using a metal halide lamp as a light source. Next, a developing solution was prepared using potassium silicate, potassium hydroxide, and water shown below and varying the 5i02 concentration. (Table 1) However, potassium hydroxide was added to adjust the pH to 12.8.

Development was carried out by rubbing the surface of the plate material with a vat impregnated with these developing solutions, and the unexposed portions of the photosensitive layer and silicone rubber layer were removed. The results are shown in Table-1. From this, the 5in2 density showed good halftone dot reproducibility within the range of the present invention.

[Developer component] Potassium silicate (Sin225-27 from 2012.5
14.5 Potassium Hydroxide Water Used Below Margin Table - [Effects of the Invention] The present invention provides an acid value of 1 using a developer consisting of a silicate and water.
By developing a waterless lithographic printing plate precursor containing a photocurable photosensitive layer containing a binder polymer of 0 to 300%, the adhesion between the photosensitive layer in the non-image area and the silicone rubber layer does not deteriorate, and the halftone dots A waterless lithographic printing plate original plate with excellent reproducibility of shadow areas can be obtained.

Claims (1)

[Claims] In a developer for a waterless lithographic printing plate precursor having a primer layer, a photocurable photosensitive layer containing a binder polymer having an acid value of 10 to 300, and a silicone rubber layer in this order on a support,
A developer for a waterless lithographic printing plate precursor, characterized in that the developer essentially consists of a silicate and water, and the SiO_2 concentration of the silicate is in the range of 0.5% to 6% by weight.