JPH0372360A - Photosensitive planographic printing plate - Google Patents

Abstract

PURPOSE:To improve a high contrast property, plate wear and liposensitivity by forming a 1st photosensitive compsn. contg. a diazo resin and a high-polymer compd. as an upper layer and a 2nd photosensitive compsn. contg. a diazo resin and a specific alkaline soluble high-polymer comd. as a lower layer on a substrate. CONSTITUTION:The layer consisting of the 1st photosensitive compsn. contg. the diazo resin and the high-polymer compd. is formed as the upper layer and the layer consisting of the 2nd photosensitive compsn. contg. the diazo resin and the alkaline soluble high- polymer compd. as the lower layer on the substrate. The alkaline soluble high-polymer compd. in the 2nd photosensitive compsn. is formed to have the easier solbility in alkalis than the high-polymer compd. in the 1st photosensitive compsn. The content of the 2nd photosensitive compsn. is increased on the side near the substrate and the content of the 1st photosensitive compsn. is increased on the side further from the substrate. The photosensitive layer having the high alkaline solubility, therefore, exists eventually on the lower layer and the photosensitive layer having the lower alkaline solubility than the alkaline solubility of the lower layer exists on the upper layer. The upper layer is the layer poor in hydrophilicity. The high contrast property, plate wear and liposensitivity are improved in this way.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a photosensitive lithographic printing plate.

[Background of the invention]

BACKGROUND ART Various photosensitive lithographic printing plates have been proposed in the past, including, for example, various photosensitive lithographic printing plates having a photosensitive layer containing a composition containing a diazo resin and an alkali-soluble polymer.

[Problem that the invention attempts to solve]

However, conventional devices of this type, such as conventional negative type PS
In the case of printing plates, the gradations are long, and this has had an undesirable effect on printed matter.

On the other hand, since the photosensitive lithographic printing plate is printed with printing ink, it is desired that the photosensitive planographic printing plate has high oil sensitivity. It is also desired that the printing durability is high.

However, it is difficult to satisfy all of the above. For example, if you try to improve the gradation as described above to obtain a hard gradation, the printing durability may be affected or the oil sensitivity may decrease. Sometimes.

In this way, it has been difficult to satisfy all of the above requirements with the conventional technology, but the present invention solves this problem and
In addition to achieving high contrast, it also has sufficient stiffness resistance.
The object of the present invention is to provide a photosensitive lithographic printing plate that is also highly oil-sensitive.

[Means for solving problems]

The above object of the present invention is achieved by a photosensitive lithographic printing plate having the following first and second photosensitive compositions on a support.

(a) A first photosensitive composition containing a diazo resin and a polymer compound. (b) A second photosensitive composition containing a diazo resin and an alkali-soluble polymer compound. However, in the present invention, the second photosensitive composition described above The alkali-soluble polymer compound in the photosensitive composition is more easily alkali-soluble than the polymer compound in the first photosensitive U acid, and
The content of the second photosensitive composition is higher on the side closer to the support, and the content of the first photosensitive composition is higher on the side farther from the support.

In the present invention, ideally, a layer consisting of the second photosensitive composition is formed on the support as a lower layer, and the first layer is formed on the support.
It is possible to have a two-layer structure in which a layer made of a photosensitive composition is formed as an upper layer.

(In this specification, for convenience, the side closer to the support is referred to as the "lower layer" and the side farther away is referred to as the "upper layer"). However, in reality, it may not always be possible to have a two-layer structure that is clearly separated, and the second photosensitive composition may be enriched in the lower layer and the first photosensitive composition may be enriched in the upper layer. It should be .

According to the present invention, as a result of the above structure, a photosensitive layer with high alkali solubility is located in the lower layer, and a photosensitive layer with lower alkali solubility than the lower layer is located in the upper layer, which results in high contrast. can be realized.

In addition, since the upper layer is a layer with poor hydrophilicity, it has high oil sensitivity and is resistant to dampening water, thereby improving oil sensitivity and stiffness resistance.

In the present invention, the term "alkali-soluble" means that it can be dissolved or swollen by an alkaline developer and can be removed.

The present invention will be explained in more detail below.

First, the first photosensitivity! Let's talk about acids. This is a component that is enriched in the upper layer on the support in the photosensitive lithographic printing plate of the present invention.

The first photosensitive composition contains a diazo resin and an alkali-soluble polymer compound, and the alkali-soluble polymer compound acts as a binder in the composition.

The polymer compound in the first photosensitive composition is preferably alkali-soluble, and is less soluble in alkali than the alkali-soluble polymer compound in the second photosensitive composition. It is. The polymer compound in the first photosensitive composition may generally be any compound as long as it is soluble in a solvent (e.g., glycol solvent, ketone solvent, ester solvent, etc.), but acrylic resin is preferred. , epoxy resins, polyurethane resins, polyvinyl formal or polyvinyl butyral resins, polycarbonate resins, polysulfone resins, styrene resins, etc., and these can also be used in the form of mixtures. Particularly preferred are acrylic resins, polyurethane resins, and polyvinyl formal resins.

The diazo resin contained in the first photosensitive composition is optional. Diazo resin functions as a photosensitive compound.

Suitable diazo resins to be contained in the first photosensitive composition include condensates of active carbonyl compounds such as formaldehyde and compounds having a diazonium group (for example, rosediazodiphenylamine); Examples include co-condensates of compounds capable of condensing with active carbonyl compounds (for example, diphenyl ether) as described in No. 48001, active carbonyl compounds, and compounds having a diazonium group.

The first photosensitive U paraboloid may contain a nonionic surfactant as an additive for improving the compatibility between the polymer compound used as a binder and the diazo resin. It may also contain a dye for coloring the photosensitive layer made of the first photosensitive composition. These additives will be described later.

Next, the second photosensitive composition will be described. In the photosensitive lithographic printing plate of the present invention, this is a component that is enriched on the lower layer side of the support.

The second photosensitive composition contains a diazo resin and an alkali-soluble polymer compound, and the alkali-soluble polymer compound is more easily soluble in alkali than the polymer compound of the first photosensitive composition. .

Here, in the second photosensitive composition, the alkali-soluble polymer compound functions as a binder.

The resin used as a binder in this way is
In general, any resin that is soluble in alkaline water or an aqueous solution containing a small amount of organic solvent may be used, but preferred examples include acrylic resin, polyvinyl alcohol,
Examples include maleic anhydride, maleic acid copolymers, and celluloses, and these may be used in combination. Acrylic resin is particularly preferred.

The diazo resin in the second photosensitive composition is optional, but preferably a co-condensed diazo resin, which is an aromatic compound having a phenolic OH group or a carboxyl group, an aromatic compound having a diazonium group, and an active carbonyl compound. Particularly preferred are diazo resins co-condensed with.

In addition, dyes and pigments for coloring the photosensitive layer, acids for accelerating development, and the like may be added to the second photosensitive composition.

In the present invention, 1. The acrylic resin preferably used to constitute the polymer compound contained in the second photosensitive composition preferably has an alcoholic hydroxyl group and/or an aromatic hydroxyl group, and a carboxylic acid group.

Monomers with alcoholic hydroxyl groups include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxypentyl (
(meth)acrylate, etc.

In addition, as a monomer having an aromatic hydroxyl group, N-(
4-hydroxyphenyl)-(meth)acrylamide,
N-(2-hydroxyphenyl-(meth)acrylate, 4-hydroxyphenyl(meth)acrylate, 2
-Hydroxyphenyl(meth)acrylate and the like.

In addition, monomers with carboxylic acid groups include (meth)
Examples include acrylic acid and maleic acid.

In addition to the monomers listed above, the acrylic resin preferably used in the present invention usually includes methyl (meth)acrylate, ethyl (meth)acrylate, acrylonitrile,
Contains methacrylonitrile, butyl (meth)acrylate, styrene, etc. as structural units.

Furthermore, the acrylic resin preferably used in the present invention may be modified with a compound such as an epoxy compound that reacts with the carboxylic acid group contained therein. Moreover, the hydroxyl group contained may be modified with a compound that reacts with the hydroxyl group, such as isocyanates.

In the present invention, polyvinyl formal or polyvinyl butyral resin can be used as a component of the polymer compound, and such resin can be obtained by condensing polyvinyl alcohol with formaldehyde or butyraldehyde. Furthermore, other than formaldehyde and butyraldehyde, any aldehyde that can be condensed may be used in combination or alone or in a condensed form.

Epoxy resin, polyurethane resin, polysulfone resin,
A commercially available styrene copolymer can be used.

In the present invention, there is no particular limitation on the molecular weight of the diazo resin used. For example, the above-mentioned co-condensed diazo resin can have an arbitrary molecular weight by varying the molar ratio of each monomer and the condensation conditions. However, in the present invention, it is generally preferred that the molecular weight is about 400 to 10
,000 diazo resins can be effectively used, more preferably from about 800 to 5,000.

In the present invention, 1. The polymer compound or alkali-soluble polymer compound in the second photosensitive composition is preferably contained in the solid content of each photosensitive composition in an amount of usually 40 to 99% by weight, more preferably 50 to 95% by weight. let In the present invention, the photosensitive diazo resin is preferably contained in an amount of usually 1 to 60% by weight, more preferably 3 to 30% by weight.

In the present invention, the photosensitive composition can contain an acid and/or an acid anhydride.

When using an acid, it can be arbitrarily selected from any organic acid or inorganic acid. The organic acid is preferably a monocarboxylic acid or a polycarboxylic acid having at least one carboxyl group. Malic acid, tartaric acid, polyacrylic acid (commercially available under the trade name Jurimer, etc.) can be preferably used. Organic acids (citric acid, oxalic acid, benzenesulfonic acid, naphthalenesulfonic acid, 4-acrylic acid, etc.) can be preferably used.
methoxy-2-hydroxybenzophenone-5=sulfonic acid, etc.) can also be used. As the inorganic acid, phosphoric acid, phosphorous acid, etc. can be used. These acids can also function as stabilizers.

When an acid anhydride is used, the type of acid anhydride is arbitrary, such as acetic anhydride, propionic anhydride, benzoic anhydride, those derived from aliphatic/aromatic monocarboxylic acids, succinic anhydride, and benzoic anhydride. Examples include those derived from aliphatic/aromatic dicarboxylic acids such as maleic acid, glutaric anhydride, and phthalic anhydride.

Such an acid or acid anhydride can be particularly included in the second photosensitive composition in order to accelerate development.

In the present invention, the photosensitive layer constituted by the photosensitive material composition can contain a dye, particularly a dye that changes color from colored to colorless or changes color upon processing. Preferably, a pigment that changes from colored to colorless is contained. However, the dye contained in the photosensitive lithographic printing plate may be contained in the photosensitive layer to form a colored photosensitive layer, or may be contained in a colored layer separate from the photosensitive layer.

In carrying out the present invention, the following can be mentioned as dyes that can be preferably used.

That is, for example, Victoria Pure Blue BOH (manufactured by Hodogaya Chemical Co., Ltd.), Oil Blue #603 (manufactured by Orient Chemical Industry Co., Ltd.), Patent Pure Blue (manufactured by Sumitomo Mikuni Chemical Co., Ltd.)
, crystal violet, brilliant green, ethyl violet, methyl violet, methyl green, erythrosin B5 basic tsuksin, malachite green, oil red, m-cresol purple, rhodamine B1 auramine, 4-p-dimethylaminophenyl imino naphthoquine, cyano - Triphenylmethane-based, diphenylmethane-based, oxazine-based, xanthine-based, iminonaphthoquinone-based, azomethine-based, or anthraquinone-based dyes such as p-diethylaminophenylacetanilide are pigments that change color from colored to colorless or to a different color. This can be cited as an example.

Particularly preferred are triphenylmethane-based and diphenylmethane-based dyes, more preferably triphenylmethane-based dyes, and Victoria Viewer Blue BOH is particularly preferred.

The above-mentioned color changing agent is preferably contained in the photosensitive Mi acid or photosensitive layer in an amount of usually about 0.5 to about 10% by weight,
More preferably, it is contained in an amount of about 1 to 5% by weight.

In the present invention, various additives can be further added.

Examples of additives include alkyl ethers (e.g., ethyl cellulose, methyl cellulose), fluorine surfactants, and nonionic surfactants (e.g., Bluronic L-64 (manufactured by Asahi Denka Corporation) to improve coating properties).
], a plasticizer to impart flexibility and abrasion resistance to the coating film (
For example, butyl phthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, diptyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, acrylic acid or methacrylic acid. Oligomers and polymers>, oil-sensitizing agents for improving the oil-sensitivity of image areas (for example, half-esterification of styrene-maleic anhydride copolymer with alcohol described in JP-A No. 55-527), etc. can be mentioned. The amount of these additives added varies depending on the object and purpose of use, but is generally preferably 0.01 to 30% by weight based on the total solid content.

In order to obtain the photosensitive lithographic printing plate of the present invention, for example, predetermined amounts of a diazo resin, a polymer compound or an alkali-soluble polymer compound, and, if necessary, various additives are mixed in a suitable solvent (methyl cellosolve, ethyl cellosolve, etc.). methyl cellosolve acetate, acetone, methyl ethyl ketone, methanol, dimethyl formamide, dimethyl sulfoxide, water or a mixture thereof, etc.) to prepare a coating solution of the photosensitive composition, which is coated on a support, dried, and Available as a printed version. The concentration of the photosensitive composition during coating is preferably in the range of 1 to 50% by weight. In this case, the coating amount of the photosensitive composition is preferably about 0.2 to 10 g/rd.

In carrying out the present invention, the photosensitive lithographic printing plate may have a structure having a colored photosensitive layer made of a photosensitive U acid containing a dye, or a colored layer made of a dye or other binder and a photosensitive composition. The structure may have two layers including a photosensitive layer and a photosensitive layer. When having two layers, either layer may be placed on the support side.

In the photosensitive planographic printing plate of the present invention, as a support,
Various types can be used. Particularly preferred is an aluminum plate. However, if an aluminum plate is used without treatment, there are problems in that the adhesion of the photosensitive composition is poor and the photosensitive composition decomposes. To eliminate this problem,
Conventionally, various proposals have been made.

For example, a method in which the surface of an aluminum plate is grained and then treated with a silicate (US Pat. No. 2.714.066), a method in which the surface of an aluminum plate is treated with an organic acid salt (US Pat. No. 2.714.
No. 066>, treatment with phosphonic acids and their derivatives (U.S. Pat. No. 3,220,832), treatment with potassium hexafluorozirconate (U.S. Pat. No. 2)
, 946.683), a method of anodizing, and a method of treating with an aqueous solution of alkali metal silicate after anodization (US Pat. No. 3,181,461).

In a preferred embodiment of the present invention, after degreasing the surface of an aluminum plate (including an aluminum laminate), the surface is sand-etched by a brush polishing method, a ball polishing method, a chemical polishing method, an electrolytic etching method, etc. Graining is applied, preferably by an electrolytic etching method which produces deep and uniform grains.

The anodizing treatment is carried out in an aqueous solution of an inorganic salt such as phosphoric acid, chromic acid, boric acid, or sulfuric acid, or an organic acid such as oxalic acid, or a mixture of two or more of these acids, preferably in an aqueous sulfuric acid solution. This is done by passing an electric current through an aluminum plate as an anode. The amount of anodic oxide film is 5-6
0 ■/dnf is preferable, more preferably 5 to 30 ■/dnf.
It is drd.

When carrying out sealing treatment in carrying out the present invention, preferably a sodium silicate aqueous solution with a concentration of 0.1 to 3% is added at a temperature of 8.
This treatment is carried out by immersion at 0 to 95°C for 10 seconds to 2 minutes.

More preferably, it is then soaked in water at a temperature of 40 to 95°C for 10 seconds to 2
Soak and process for a minute.

The photosensitive lithographic printing plate of the present invention can be exposed and developed by conventional methods. That is, for example, a negative leaf image can be obtained with respect to the original image by exposing the transparent original image having a line image, halftone image, etc. to light, and then developing with an aqueous developer.

Light sources suitable for exposure include carbon arc lamps, mercury lamps, xenon lamps, metal halide lamps, strobes, and the like.

Any method can be used to develop the imagewise exposed photosensitive lithographic printing plate (hereinafter sometimes referred to as "RPS plate"), and for example, various conventionally known methods can be used.

Specifically, methods include immersing an image-exposed PS plate in a developer, spraying the developer from multiple nozzles onto the photosensitive layer of the PS plate, and exposing the PS plate using a sponge moistened with the developer. Various methods can be used, such as wiping the layer and applying a developer to the surface of the photosensitive layer of the PS plate with a roller. Further, after applying the developer to the photosensitive layer of the 13th plate in this manner, the surface of the photosensitive layer can be lightly rubbed with a brush or the like.

Any developer can be used to develop the photosensitive lithographic printing plate of the present invention as long as it can develop the plate.

Preferably, a developer containing a specific organic solvent, an alkaline agent, and water as essential components can be used.

The specific organic solvent used herein refers to a solvent that can dissolve or swell the non-exposed area (non-image area) of the layer made of the photosensitive composition when it is contained in the developer, and is capable of dissolving or swelling at room temperature (20 It is preferable to use an organic solvent having a solubility in water of 10% by weight or less at ℃).Such organic solvents only need to have the above-mentioned characteristics, and are not limited to the following: However, examples include carboxylic acid esters such as ethyl acetate, propyl acetate, butyl acetate, ajuyl acetate, benzyl acetate, ethylene glycol monobutyl acetate, butyl acetate, butyl levulinate; ethyl butyl Ketones such as ketones, methyl isobutyl ketone, and cyclohexanone; Alcohols such as ethylene glycol monobutyl ether, ethylene glycol benzyl ether, ethylene glycol monophenyl ether, benzyl alcohol, methylphenyl carbinol, n-amyl alcohol, and methyl amyl alcohol ; Alkyl-substituted aromatic hydrocarbons such as xylene; halogenated hydrocarbons such as methylene dichloride, ethylene dichloride, and monochlorobenzene. These organic solvents may be used alone or in combination of two or more. Among the solvents, ethylene glycol monophenylniter and benzyl alcohol are particularly effective.The content of these organic solvents in the developer is preferably approximately 1 to 20% by weight, particularly 2 to 20% by weight.
More preferable results are obtained when the amount is 10% by weight.

On the other hand, preferred alkaline agents contained in the developer include (A) sodium silicate, potassium silicate, potassium hydroxide, sodium hydroxide, lithium hydroxide, di- or tri-sodium phosphate or ammonium salt; Inorganic alkaline agents such as sodium metasilicate, sodium carbonate or ammonium; (B) mono-, di- or trimethylamine, mono;

Examples include organic amine compounds such as di- or triethylamine, mono- or di-isopropylamine, n-butylamine, mono-, di- or triethanolamine, mono-, di- or tri-isopropanolamine, ethylene diamine, and ethylenecyamine.

The content of these alkaline agents in the developer is usually 0.
It is preferably 0.05 to 4% by weight, more preferably 0.5 to 2% by weight.

Further, in order to further improve storage stability, printing durability, etc., it is preferable to include a water-soluble sulfite in the developer. Such water-soluble sulfites are preferably alkali or alkaline earth metal salts of sulfite, such as sodium sulfite, potassium sulfite, lithium sulfite, magnesium sulfite, and the like. The content of these sulfites in the developer composition is usually preferably 0.05 to 4% by weight, more preferably 0.1 to 1% by weight.

If such a developer is brought into contact with the photosensitive lithographic printing plate after development and exposure, or is rubbed with the developer, the exposed areas of the photosensitive composition layer will be removed after 10 to 60 seconds at room temperature to 40°C. The photosensitive composition in the non-exposed areas is completely removed without adversely affecting the photosensitive composition.

The developing conditions can be appropriately selected depending on the developing method. - For example, in the development method by immersion, a method of immersing the film in a developer solution at about 10 to 40° C. for about 10 to 80 seconds can be used.

〔Example〕

Examples of the present invention will be described below along with comparative examples. As a matter of course, the present invention is not limited to the following examples.

Example 1 An aluminum plate that has been grained, anodized, and treated with an aqueous sodium silicate solution is used as a support. First, photosensitive liquid 2 shown below is coated on this using a Whaler, and dried to form the lower layer. (a layer enriched in the second photosensitive composition) was formed. Thereafter, Photosensitive Liquid 1 shown below was applied using a wire bar and dried to form an upper layer (a layer enriched with the first photosensitive composition).

The weight of the coating film after drying is 1.2g/coating film made of photosensitive liquid 2.
d, and the coating weight after applying photosensitive liquid 1 is 1.7 g/
It was rrr.

The structure of the layer that is finally formed is not necessarily one where the two layers are clearly separated, but the photosensitive liquid is applied to the surface of the coating film.
It can be easily inferred that there are many components in the photosensitive liquid 2 near the aluminum plate that is the support.

Photosensitive liquid 2 Photosensitive liquid I Comparative example 1 Photosensitive liquid 2 was applied to the same aluminum plate as in Example 1 so that the coating weight after drying was 1.7 g/rrr.

Comparative Example 2 Photosensitive liquid 1 was applied to the same aluminum plate as in Example 2 so that the coating weight after drying was 1.7 g/rd.

Evaluation of Example 1 and Comparative Example 1.2 A gray scale with a density difference of 0.15 and a negative original were placed on the plates of Example 1 and Comparative Example 1.2, and they were vacuum-adhered, and a power of 4 kW was applied.
40 from a distance of 60 cm using a metal halide lamp.
After exposure for seconds, 5DN-21 (manufactured by Konica ■) was soaked with water for 4 seconds.
It was immersed for 50 seconds at 25° C. in a developer diluted twice as much.

Thereafter, it was developed by rubbing lightly with absorbent cotton.

After development, 5GW-2 (manufactured by Konica ■) diluted twice with water was spread on the plate with a sponge, dried, and gummed.

Table 1 shows the solid gray scale of the plate after development Table 2 The obtained plate is printed using a Heidelberg GTO printing machine, and ink is uniformly applied to the entire printed area of the paper from the beginning of printing. The number of sheets up to (the number of sheets with gum removed) and the number of sheets to be printed were determined. These are shown in Table 2.

Margin Example 2 The same aluminum plate as in Example 1 was used as a support, and photosensitive liquid 2 was first applied thereon using a Whaler and dried. Next, photosensitive liquid 3 below was applied using a wire bar and dried.

The coating weight after applying photosensitive liquid 2 is 1.0 g/rrf,
The coating weight after applying photosensitive liquid 3 was 2.0 g/n.

Photosensitive liquid 3 The number of sheets from which gum was removed and the number of printed sheets were evaluated.

The results are shown in Table-3.

Table 3 Comparative Example 3 Photosensitive liquid 3 was applied onto the same aluminum plate as in Example 2 so that the coating weight after drying was 2.0 g/rd.

Evaluation of Example 2 and Comparative Examples 1 and 3 In the same way as Example 1, etc., Example 2 and Comparative Examples 1 and 3 were evaluated.
As can be seen from the above results, the photosensitive lithographic printing plate of Example 12 of the present invention was compared with the comparative example. Compared to No. 1 and No. 2.3, it has excellent gradation (difference in the number of petar clear steps), gum removal performance, and rigidity resistance.

〔Effect of the invention〕

As described above, the photosensitive lithographic printing plate of the present invention has the effect of realizing high contrast, sufficient stiffness resistance, high oil sensitivity, and rapid printing.

Claims (1)

[Claims] 1. Having the following first and second photosensitive compositions on a support, (a) a first photosensitive composition containing a diazo resin and a polymer compound (b) A second photosensitive composition containing a diazo resin and an alkali-soluble polymer compound The alkali-soluble polymer compound in the second photosensitive composition has a higher content than the polymer compound in the first photosensitive composition. It is easily alkali soluble, and the content of the second photosensitive composition is high on the side closer to the support, and the content of the first photosensitive composition is higher on the side farther from the support. Characteristic photosensitive planographic printing plate.