JP2023064817A - Photosensitive resin printing original plate - Google Patents

Abstract

To provide a photosensitive resin printing original plate which is excellent in adhesion between a photosensitive resin layer and an IR-sensitive layer.SOLUTION: A photosensitive resin printing original plate has a photosensitive resin layer containing a polyamide resin having a polyether structure, an intermediate layer and an IR-sensitive layer in this order on a support, in which the IR-sensitive layer contains polyvinyl alcohol having a degree of saponification of 60-100 mol% and an average degree of polymerization of 300-3,000, and the intermediate layer contains a polyamide resin having a basic nitrogen atom and/or a polyether structural unit.SELECTED DRAWING: None

Description

The present invention relates to a photosensitive resin printing plate precursor.

In the fields of letterpress printing and flexographic printing, CTP (computer to plate) technology, known as digital image forming technology, has become commonplace. In the CTP technique, an image mask is formed by digital data on the mask layer element of a photosensitive resin printing plate precursor having a mask layer element. In this method, a relief pattern is formed by partially photocuring a layer.

As a photosensitive resin printing plate precursor suitable for such CTP technology, a photosensitive resin layer (A) containing a polyamide having a hydrophilic group and a compound having an ethylenically unsaturated bond is formed on a support, and at least one layer of A photosensitive resin printing plate precursor having, in this order, an intermediate layer (B) and a water-insoluble heat-sensitive mask layer (C) containing an infrared absorbing material, wherein the intermediate layer (B) comprises polyvinyl alcohol and/or partially saponified polyvinyl A photosensitive resin printing plate precursor characterized by containing an alcohol and a polyamide having a hydrophilic group (see, for example, Patent Document 1), or at least (A) a support, (B) a photosensitive resin layer, and (C) A water-developable photosensitive letterpress printing original plate comprising an oxygen-blocking split layer and (D) a carbon black-containing water-soluble or water-dispersible heat-sensitive mask layer laminated in order, wherein (B) a photosensitive resin layer comprises , a synthetic polymer compound, a photopolymerizable unsaturated compound, and a photopolymerization initiator, wherein the synthetic polymer compound contains a polyamide or polyether urea urethane containing a tertiary nitrogen atom, and (C ) A photosensitive letterpress printing original plate (see, for example, Patent Document 2) has been proposed in which the oxygen-blocking partition layer contains polyvinyl alcohol having a degree of saponification of 60 to 85 mol% and a degree of polymerization of 200 to 800. .

JP 2012-22229 A WO2017/056763

Patent Literature 1 describes, as a binder resin for a photosensitive resin layer, a polyamide resin having an amino group such as a piperazine ring or a polyether segment such as polyethylene glycol in order to impart developability. However, when a photosensitive resin layer containing such a polyamide resin is combined with a water-soluble or water-dispersible infrared-sensitive layer as described in Patent Document 2, the adhesion between the photosensitive resin layer/infrared-sensitive layer is reduced. It has been clarified by the studies of the present inventors.

SUMMARY OF THE INVENTION An object of the present invention is to provide a photosensitive resin printing plate precursor having excellent adhesion between a photosensitive resin layer and an infrared-sensitive layer.

The present invention provides a photosensitive resin printing plate precursor having, on a support, a photosensitive resin layer containing a polyamide resin having a polyether structure, an intermediate layer and an infrared-sensitive layer in this order, wherein the infrared-sensitive layer has a degree of saponification. A photosensitive resin printing plate precursor containing 60 to 100 mol % of polyvinyl alcohol having an average degree of polymerization of 300 to 3,000, and an intermediate layer containing a polyamide resin having basic nitrogen atoms and/or polyether structural units. .

The photosensitive resin printing plate precursor of the present invention has excellent adhesion between the photosensitive resin layer and the infrared sensitive layer.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail.

The photosensitive resin printing plate precursor of the invention (hereinafter sometimes abbreviated as "printing plate precursor") has a photosensitive resin layer, an intermediate layer and an infrared-sensitive layer in this order on a support. The support has a function of holding the photosensitive resin layer in the printing plate precursor. The photosensitive resin layer has a function of forming an uneven pattern (relief) corresponding to the image mask by irradiation with actinic rays through the image mask. The infrared-sensitive layer has the action of forming an image mask by partial decomposition (ablation) by infrared rays. The intermediate layer brings the photosensitive resin layer and the infrared-sensitive layer into close contact with each other, and has the effect of suppressing migration of low-molecular-weight components from the photosensitive resin layer to the infrared-sensitive layer.

The printing plate precursor of the invention may further have an easy-adhesion layer between the support and the photosensitive resin layer, if necessary, to increase the adhesion between the support and the photosensitive resin layer. can be done. In addition, a protective layer may be provided on the infrared-sensitive layer to prevent the infrared-sensitive layer from being scratched by an external force, thereby improving the scratch resistance of the infrared-sensitive layer in the photosensitive resin printing plate precursor.

In the printing plate precursor of the invention, the photosensitive resin layer contains a polyamide resin having a polyether structure. By having a polyamide resin containing a polyether structure, the solubility in a developing solution containing water as a main component can be improved. In particular, when the above-mentioned infrared-sensitive layer can be removed with a developer containing water as a main component, the photosensitive resin layer, the intermediate layer and the infrared-sensitive layer can be combined and developed with a developer containing water as a main component. can. The photosensitive resin layer preferably further contains a compound having an ethylenic double bond and a photopolymerization initiator. When such a photosensitive resin layer is imagewise irradiated with light such as ultraviolet rays, free radicals are generated from the photopolymerization initiator in the photosensitive resin layer in the exposed areas. The generated free radicals can induce radical polymerization between compounds having an ethylenic double bond and form a relief for obtaining a desired printed image due to the crosslinked structure. When the aforementioned polyamide resin has an ethylenic double bond, radical polymerization also occurs between the polyamide resin and a compound having an ethylenic double bond. This makes it possible to further promote photocuring and improve the image reproducibility of the printing plate.

Polyether structures include, for example, polyethylene oxide and polypropylene oxide. You may use 2 or more types of these. Among these, polyethylene oxide is preferable, and the number average molecular weight of the polyethylene oxide portion is preferably 200 or more and 6,000 or less. By adjusting the number average molecular weight of the polyethylene oxide to 200 or more, the solubility in the developing solution containing water as the main component can be improved, and the aggregation of the waste developing solution can be suppressed. On the other hand, by setting the number average molecular weight of the polyethylene oxide portion to 6,000 or less, compatibility with other components in the photosensitive resin layer can be improved. The polyamide resin containing these polyethers imparts flexibility to the relief obtained by photocuring the photosensitive resin layer, and can be easily adjusted to a hardness suitable for various printing methods.

A polyamide resin having a polyether is, for example, α,ω-diaminopolyoxyethylene obtained by adding acrylonitrile to both ends of polyethylene glycol or the like and hydrogen-reducing this, or succinic anhydride at both ends of polyethylene glycol. A component having a polyether such as a compound to which a dicarboxylic acid is added can be obtained by condensation polymerization or polyaddition reaction, if necessary, together with other diamines, dicarboxylic acids, aminocarboxylic acids, lactams, etc. .

Examples of diamines include hexamethylenediamine and dodecamethylenediamine. Examples of dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid, Aromatic dicarboxylic acids such as sodium 5-sulfoisophthalate; Aliphatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and dicyclohexyl-4,4′-dicarboxylic acid; Succinic acid, oxalic acid , adipic acid, sebacic acid, and aliphatic dicarboxylic acids such as decanedicarboxylic acid. Examples of aminocarboxylic acids include ω-aminocaproic acid, ω-aminoenanthic acid, ω-aminocaprylic acid, ω-aminobergonic acid, ω-aminocapric acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and the like. be done. Rakutam includes, for example, caprolactam, enantholactam, capryllactam, laurolactam and the like. You may use 2 or more types of these.

It is preferable to use a total of 20 to 90 mol % of polyether-containing components in the sum of all components constituting the polyamide resin, ie, aminocarboxylic acid (including the case of lactam as a raw material), dicarboxylic acid and diamine. By using 20 mol % or more of the polyether-containing component, the solubility in the developing solution containing water as the main component can be further improved, and aggregation of the developer waste solution can be further suppressed. It is more preferable to use such a component in an amount of 30 mol % or more. On the other hand, by using 90 mol % or less of the component containing polyether, it is possible to suppress water absorption during storage of the printing plate and maintain the thickness accuracy of the printing plate at a high level.

The weight average molecular weight of the polyamide resin having a polyether structure is preferably 10,000 or more and 200,000 or less. Here, the weight average molecular weight can be determined by GPC measurement. More specifically, using a Wyatt Technology gel permeation chromatograph-multi-angle light scattering photometer, the weight average molecular weight can be measured under the conditions of column temperature: 40 ° C. and flow rate: 0.7 mL / min. . Polyethylene oxide and polyethylene glycol are used as standard samples.

The content of the polyamide resin having a polyether structure in the photosensitive resin layer is preferably 30 to 70% by mass based on the solid content.

A compound having an ethylenic double bond refers to a compound having an ethylenic double bond and having a molecular weight of less than 10,000. The molecular weight of the compound having an ethylenic double bond is preferably 2,000 or less.

Examples of compounds having an ethylenic double bond include (meth)acrylates described in WO 2017/038970, glycerol di(meth)acrylate, and (meth)acrylic acid adducts of propylene glycol diglycidyl ether. , tetrahydrofurfuryl (meth)acrylate and the like. You may contain 2 or more types of these. Here, (meth)acrylate is a generic term for acrylate and methacrylate, and (meth)acrylic acid is a generic term for acrylic acid and methacrylic acid.

The content of the compound having an ethylenic double bond in the photosensitive resin layer is preferably 10-60% by mass.

As the photopolymerization initiator, those having a function of generating radicals by self-decomposition or hydrogen abstraction upon absorption of light are preferably used. Examples include benzoin alkyl ethers, benzophenones, anthraquinones, benzyls, acetophenones, diacetyls and the like. You may contain 2 or more types of these.

The content of the photopolymerization initiator in the photosensitive resin layer is preferably 0.1 to 10 mass %.

In the photosensitive resin layer, if necessary, a binder resin other than a polyamide resin having a polyether structure, a compatibility aid, an ink repellent agent, a polymerization inhibitor, a dye, a pigment, a surfactant, an antifoaming agent, an ultraviolet Absorbents, fragrances and the like may also be included.

By including a compatibility aid in the photosensitive resin layer, the compatibility of the components constituting the photosensitive resin layer is enhanced, the bleeding out of low molecular weight components is suppressed, and the flexibility of the photosensitive resin layer is improved. can be done. Examples of compatible aids include polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol and derivatives thereof. The content of the compatibility aid in the photosensitive resin layer is preferably 30% by mass or less.

By containing an ink-repellent agent in the photosensitive resin layer, it is possible to suppress ink from entering the concave portions of the relief during printing and improve reproducibility. Examples of ink-repellent agents include silicone compounds and fluorine-containing compounds. The content of the ink repellent agent in the photosensitive resin layer is preferably 5% by mass or less.

Thermal stability can be improved by containing a polymerization inhibitor in the photosensitive resin layer. Examples of polymerization inhibitors include phenols, hydroquinones, catechols, and hydroxylamine derivatives. You may contain 1 or more types of these. The content of the polymerization inhibitor in the photosensitive resin layer is preferably 0.001 to 5 mass %.

Next, the infrared sensitive layer will be explained. (1) The infrared-sensitive layer efficiently absorbs the infrared laser, and the heat evaporates or ablates part or all of the layer, causing a difference in optical density between the laser-irradiated and non-irradiated areas. (2) practically blocking ultraviolet light. It should be noted that the practical blocking of ultraviolet light here means that the optical density of the infrared-sensitive layer is 2.0 or more, and more preferably 2.5 or more. Optical density is generally represented by D and is defined by the following equation.
D= _log10 (100/T)= _log10 (I0/I)
Here, T is the transmittance (in units of %), I0 is the incident light intensity when measuring the transmittance, and I is the transmitted light intensity.

The optical density in the present invention refers to a value calculated from the measured value of the transmitted light intensity with the incident light intensity kept constant. The optical density can be measured with a Macbeth transmission densitometer "TR-927" (manufactured by Kollmorgen Instruments Corp.) using an orthochromatic filter.

The infrared sensitive layer in the present invention contains polyvinyl alcohol. Furthermore, it is preferable to contain an infrared absorbing substance.

The infrared-sensitive layer contains polyvinyl alcohol having a degree of saponification of 60 to 100 mol % and an average degree of polymerization of 300 to 3,000. By containing such polyvinyl alcohol, it is possible to improve the dispersibility of the infrared-absorbing substance described below and improve the film formability of the infrared-sensitive layer. In addition, it suppresses the migration of a compound having an ethylenic double bond, which is a low molecular weight component that is generally highly lipid-soluble, contained in the photosensitive resin layer to the infrared-sensitive layer, and suppresses the cohesive failure of the infrared-sensitive layer. , the adhesion between the photosensitive resin layer and the infrared sensitive layer can be improved.

Here, the degree of saponification and the degree of polymerization of polyvinyl alcohol are values measured according to JIS K 6726-1994 (polyvinyl alcohol test method). Moreover, when two or more polyvinyl alcohols are contained in the infrared-sensitive layer, it means the degree of saponification and the degree of polymerization of the two or more polyvinyl alcohols as a whole.

By setting the degree of saponification of polyvinyl alcohol in the infrared-sensitive layer to 60 mol% or more, the solubility in a developing solution containing water as a main component can be improved, and the photosensitive resin layer, the intermediate layer, and the infrared-sensitive layer are combined. can be developed with a developer containing water as a main component. Furthermore, it suppresses the migration of the compound having an ethylenic double bond, which is a low molecular weight component that is generally highly lipid-soluble, contained in the photosensitive resin layer to the infrared-sensitive layer, and suppresses the cohesive failure of the infrared-sensitive layer. , the adhesion between the photosensitive resin layer and the infrared sensitive layer can be improved. On the other hand, the degree of saponification of polyvinyl alcohol in the infrared-sensitive layer is preferably 97% or less, and the adhesion between the photosensitive resin layer and the infrared-sensitive layer can be further improved.

Moreover, by setting the average degree of polymerization of the polyvinyl alcohol contained in the infrared-sensitive layer to 300 or more, the film strength of the infrared-sensitive layer can be improved, and the scratch resistance of the infrared-sensitive layer in the manufacturing process can be improved. Furthermore, it suppresses the migration of the compound having an ethylenic double bond, which is a low molecular weight component that is generally highly lipid-soluble, contained in the photosensitive resin layer to the infrared-sensitive layer, and suppresses the cohesive failure of the infrared-sensitive layer. , the adhesion between the photosensitive resin layer and the infrared sensitive layer can be improved. The average degree of polymerization is more preferably 1,000 or more. On the other hand, by setting the average degree of polymerization to 3,000 or less, the infrared-sensitive layer can be easily formed. Furthermore, it suppresses the migration of the compound having an ethylenic double bond, which is a low molecular weight component that is generally highly lipid-soluble, contained in the photosensitive resin layer to the infrared-sensitive layer, and suppresses the cohesive failure of the infrared-sensitive layer. , the adhesion between the photosensitive resin layer and the infrared sensitive layer can be improved. The average degree of polymerization is more preferably 2,500 or less.

The content of polyvinyl alcohol in the infrared-sensitive layer is preferably 10% by mass or more based on the total solid content from the viewpoint of forming the infrared-sensitive layer more easily. On the other hand, the content of polyvinyl alcohol in the infrared-sensitive layer is preferably 80% by mass or less in the total solid content from the viewpoint of improving the abrasion efficiency.

As the infrared absorbing substance, substances having absorption characteristics in the wavelength range of 750 nm to 20,000 nm are preferable. Inorganic pigments such as copper, and dyes such as phthalocyanines, substituted phthalocyanine derivatives, cyanine dyes, merocyanine dyes, polymethine dyes, and metal thiolate dyes are included. You may contain 2 or more types of these. Among these, carbon black is preferable from the viewpoint of ablation efficiency and ultraviolet absorption performance.

Carbon black preferably has an anionic group. By having an anionic group, the dispersibility of carbon black can be improved without using a dispersing agent. Therefore, the anionic group is preferably a sulfo group or a carboxyl group. A sulfo group has a large dissociation constant in water, and has a large effect of suppressing aggregation of carbon black in a dispersion of the infrared-sensitive layer composition described later. On the other hand, the carboxyl group suppresses aggregation of carbon black due to solvent shock, which tends to occur when an organic solvent such as a lower alcohol is added to the dispersion of the infrared-sensitive layer composition described later, and suppresses coating defects in the infrared-sensitive layer. can do.

Carbon black having a carboxyl group as an anionic group preferably has a lactone group. A carboxyl group has a low dissociation constant in water and is easily affected by the functional groups of other components and pH. Therefore, carbon black having a carboxyl group tends to aggregate easily. By having a lactone group, which is not present, it becomes a steric hindrance to electrostatic interactions with other components, and has the effect of suppressing aggregation. Therefore, carbon black having a carboxyl group and a lactone group can improve dispersibility in polyvinyl alcohol.

From the viewpoint of improving the abrasion efficiency, the content of the infrared-absorbing substance in the infrared-sensitive layer is preferably 5% by mass or more based on the total solid content. On the other hand, from the viewpoint of improving the scratch resistance of the infrared-sensitive layer, the content of the infrared-absorbing substance in the infrared-sensitive layer is preferably 80% by mass or less based on the total solid content.

Moreover, it is preferable that the infrared-sensitive layer in the present invention contains an ultraviolet-absorbing substance that blocks ultraviolet rays. As the ultraviolet absorbing substance, a substance having absorption characteristics in a wavelength range of 300 to 400 nm is preferable, and examples thereof include benzotriazole-based compounds, triazine-based compounds, and benzophenone-based compounds. You may contain 2 or more types of these.

The infrared-sensitive layer may contain other polymers, fillers, surfactants, coating aids and the like within limits not impairing the effects of the present invention. Other polymers include, for example, polyacrylic acid, polyester, polyamide and derivatives thereof. You may contain 2 or more types of these.

Next, the intermediate layer will be explained. In the printing plate precursor of the invention, the intermediate layer contains a polyamide resin having basic nitrogen atoms and/or a polyether structure. The basic nitrogen atom and the polyether structure are hydrophilic groups, and having such a hydrophilic group can improve the solubility in a developer containing water as a main component in the development step. In addition, by using such a polyamide resin for the intermediate layer, the adhesiveness between the photosensitive resin layer and the infrared-sensitive layer is excellent, so the adhesiveness between the photosensitive resin layer and the infrared-sensitive resin layer can be improved. From the viewpoint of further improving the solubility in a developer containing water as a main component, it preferably has a basic nitrogen atom.

Basic nitrogen atoms include, for example, piperazine rings and nitrogen atoms contained in amino groups such as N,N-dialkylamino groups. You may use 2 or more types of these. From the viewpoint of further improving solubility in a developer containing water as a main component, it preferably has a basic nitrogen atom in its main chain, and more preferably has a piperazine ring in its main chain.

Polyamide resin having a basic nitrogen atom in the main chain, for example, a component having a basic nitrogen atom, optionally together with other diamines, dicarboxylic acids, ω-amino acids, lactams, etc., condensation polymerization or polyaddition reaction can be obtained by As the component having a basic nitrogen atom, diamines, dicarboxylic acids, amino acids, etc. having a piperazine ring or an N,N-dialkylamino group are preferred, and those having a piperazine group are more preferred.

Components having a basic nitrogen atom include, for example, N,N'-bis(aminomethyl)-piperazine, N,N'-bis(β-aminoethyl)-piperazine, N,N'-bis(γ-amino benzyl)-piperazine, N-(β-aminoethyl)piperazine, N-(β-aminopropyl)piperazine, N-(ω-aminohexyl)piperazine, N-(β-aminoethyl)-2,5-dimethylpiperazine , N,N-bis(β-aminoethyl)-benzylamine, N,N-bis(γ-aminopropyl)-benzylamine, N,N′-dimethyl-N,N′-bis(γ-aminopropyl) - diamines such as ethylenediamine, N,N'-dimethyl-N,N'-bis(γ-aminopropyl)-tetramethylenediamine; N,N'-bis(carboxymethyl)-piperazine, N,N'-bis (Carboxymethyl)-methylpiperazine, N,N'-bis(carboxymethyl)-2,6-dimethylpiperazine, N,N'-bis(β-carboxyethyl)-piperazine, N,N-bis(carboxymethyl) -methylamine, N,N-bis(β-carboxyethyl)-ethylamine, N,N-bis(β-carboxyethyl)-methylamine, N,N-di(β-carboxyethyl)-isopropylamine, N, Dicarboxylic acids such as N'-dimethyl-N,N'-bis-(carboxymethyl)-ethylenediamine, N,N'-dimethyl-N,N'-bis-(β-carboxyethyl)-ethylenediamine and lower alkyls thereof esters and acid halides, N-(aminomethyl)-N'-(carboxymethyl)-piperazine, N-(aminomethyl)-N'-(β-carboxyethyl)-piperazine, N-(β-aminoethyl) -N'-(β-carboxyethyl)-piperazine, N-carboxymethylpiperazine, N-(β-carboxyethyl)piperazine, N-(γ-carboxyhexyl)piperazine, N-(ω-carboxyhexyl)piperazine, N -(aminomethyl)-N-(carboxymethyl)-methylamine, N-(β-aminoethyl)-N-(β-carboxyethyl)-methylamine, N-(aminomethyl)-N-(β-carboxy ω-amino acids such as ethyl)-isopropylamine, N,N'-dimethyl-N-(aminomethyl)-N'-(carboxymethyl)-ethylenediamine, and the like.

Other diamines, dicarboxylic acids, ω-amino acids, and lactams include those exemplified as raw materials for the polyamide resin in the photosensitive resin layer.

Polyamide resins having a polyether structure include those exemplified for the photosensitive resin layer.

The polyamide resin used for the intermediate layer contains all the components constituting the polyamide resin, namely aminocarboxylic acid (including the case of lactam as a raw material), dicarboxylic acid and diamine, a component having a basic nitrogen atom and polyether. It is preferable to use a total of 20 to 90 mol % of the components having By using 20 mol % or more of the above components, the solubility in the developing solution containing water as the main component can be further improved, and aggregation of the developer waste solution can be further suppressed. It is more preferable to use such a component in an amount of 30 mol % or more. On the other hand, by using 90 mol % or less of the above components, it is possible to suppress water absorption during storage and maintain the thickness accuracy of the printing plate at a high level. Here, the total of the component having a basic nitrogen atom and the component having a polyether means, when only either the component having a basic nitrogen atom or the component having a polyether is used, When both the nitrogen atom-containing component and the polyether-containing component are used, the sum is meant.

The weight average molecular weight of the polyamide resin having a basic nitrogen atom and/or polyether structure is preferably 10,000 or more and 200,000 or less. Here, the weight-average molecular weight can be determined by GPC measurement in the same manner as the polyamide resin in the photosensitive resin layer.

The printing plate precursor of the invention may have two or more intermediate layers. For example, by having an intermediate layer 1 having excellent adhesion to the photosensitive resin layer on the photosensitive resin layer side and an intermediate layer 2 having excellent adhesion to the infrared sensitive layer on the infrared sensitive layer side, the photosensitive resin Adhesion between layers/infrared-sensitive layers can be further improved.

When there are two intermediate layers, the intermediate layer on the infrared-sensitive layer side (hereinafter sometimes referred to as "intermediate layer 2") is polyvinyl alcohol having a saponification degree of 60 to 100 mol% and an average polymerization degree of 300 to 3,000. It is preferable to contain By containing the above-mentioned polyvinyl alcohol in the intermediate layer 2 in contact with the infrared-sensitive layer, the adhesion with the infrared-sensitive layer containing polyvinyl alcohol is further improved. can be improved.

Here, the degree of saponification and degree of polymerization of polyvinyl alcohol in the intermediate layer 2 can be measured according to JIS K 6726-1994 (polyvinyl alcohol test method) in the same manner as the polyvinyl alcohol in the infrared-sensitive layer.

In the case of having two intermediate layers, the intermediate layer on the side of the photosensitive resin layer (hereinafter sometimes referred to as "intermediate layer 1") preferably contains a polyamide resin having a polyether structure, and is photosensitive. Adhesion with the resin layer can be further improved.

The thickness of the intermediate layer is preferably 0.1 to 3 μm. By setting the thickness of the intermediate layer to 0.1 μm, the adhesion to the infrared-sensitive layer can be further improved. More preferably, the thickness of the intermediate layer is 0.3 μm or more. On the other hand, by setting the thickness of the intermediate layer to 3 μm or less, it is possible to form a deep relief of the recessed portion image, thereby improving the reproducibility of the blanked character image. More preferably, the thickness of the intermediate layer is 2 μm or less. When two or more intermediate layers are provided, the total thickness is preferably within the above range.

Next, the support will be described. Examples of the support include plastic sheets such as polyester, synthetic rubber sheets such as styrene-butadiene rubber, and metal plates such as steel, stainless steel, and aluminum. The thickness of the support is preferably in the range of 100 to 350 μm from the viewpoint of handleability and flexibility.

The support is preferably treated for easy adhesion, so that the adhesion to the relief and floor layer can be improved. Examples of the adhesive treatment method include mechanical treatment such as sandblasting, physical treatment such as corona discharge, and chemical treatment such as coating. Among these, from the viewpoint of adhesion, it is preferable to provide an easy-adhesion layer by coating.

The printing plate precursor of the invention may optionally have a protective layer on the infrared-sensitive layer.

Examples of protective layers include plastic sheets made of polyester, polyethylene, polypropylene, and the like. The thickness of the protective layer is preferably 10 to 150 μm from the viewpoint of handleability and flexibility.

Next, the method for producing a printing plate precursor according to the invention will be described by taking as an example a case in which a support has a photosensitive resin layer, an intermediate layer, an infrared-sensitive layer and a protective layer.

For example, a polyamide resin having a polyether structure, a compound having an ethylenic double bond and other additives are heated and dissolved in a solvent to obtain a photosensitive resin composition solution. Examples of solvents include water/alcohol mixed solvents.

A photosensitive resin composition solution is cast on a support having an easily adhesive layer, if necessary, and dried to form a photosensitive resin layer. Next, a photosensitive resin printing plate precursor can be obtained by adhering the protective layer formed with the intermediate layer and the infrared sensitive layer onto the photosensitive resin layer. A protective layer comprising an intermediate layer and an infrared-sensitive layer is formed, for example, by coating the protective layer with an infrared-sensitive layer composition dispersion containing the components of the infrared-sensitive layer described above, drying, and forming the intermediate layer. Examples include a method of applying an intermediate layer composition solution containing the components and drying the solution.

A method for producing a printing plate using the photosensitive resin printing plate precursor of the present invention will be described. It is preferable to have an exposure step of partially photocuring the photosensitive resin layer of the photosensitive resin printing plate precursor and a development step of removing the uncured portion of the photosensitive resin layer with a liquid containing water.

In the exposure step, the photosensitive resin printing plate precursor from which the protective layer has been removed, if any, is mounted on a digital imager having an infrared laser such as a fiber laser, and the infrared sensitive layer is decomposed and evaporated (ablation). to form an image mask. Thereafter, it is preferable to irradiate ultraviolet rays having a wavelength of 300 to 400 nm through an image mask formed from the infrared sensitive layer to photocure the exposed portions of the photosensitive resin layer. Examples of the exposure light source include high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, carbon arc lamps, chemical lamps, UV-LED lamps, and the like.

In the developing step, it is preferable to remove the photosensitive resin layer in the unexposed areas with a liquid containing water. Examples of the developing device include a spray type developing device and a brush type washing machine.

Furthermore, if necessary, a post-exposure step of irradiating with ultraviolet rays may be provided after development. The post-exposure step makes it possible to make the relief stronger by reaction of compounds with unreacted ethylenic double bonds.

The photosensitive resin printing plate precursor and printing plate of the present invention can be used for letterpress printing, dry offset printing, flexographic printing, etc. using a label printing rotary press or an intermittent rotary press. Among these, it can be preferably used for relief printing applications and dry offset printing applications.

EXAMPLES The present invention will be described in detail below with reference to examples.

<Synthesis of polyamide resin>
Synthesis Example 1: Synthesis of polyamide resin 1 Acrylonitrile was added to both ends of polyethylene glycol having a number average molecular weight of 600, and hydrogen reduction was performed to obtain an equimolar salt of α,ω-diaminopolyoxyethylene and adipic acid 80. 20 mol % of an equimolar salt of hexamethylenediamine and adipic acid was melt-polymerized to obtain a water-soluble polyamide resin 1 having polyethylene oxide in the main chain. In addition, using Wyatt Technology's gel permeation chromatograph-multi-angle light scattering photometer, column temperature: 40 ° C., flow rate: 0.7 mL / min, weight using polyethylene oxide and polyethylene glycol as standard samples The average molecular weight was measured to be 80,000.

Synthesis Example 2: Synthesis of polyamide resin 2 Acrylonitrile was added to both ends of polyethylene glycol having a number average molecular weight of 600, and hydrogen reduction was performed to obtain an equimolar salt of α,ω-diaminopolyoxyethylene and adipic acid 40. 100 parts by mass of a mixture of 20 mol% of ε-caprolactam, 40 mol% of an equimolar salt of N-(2-aminoethyl)piperazine and adipic acid, and 100 parts by mass of water were placed in a stainless steel autoclave, and the air inside was was replaced with nitrogen gas, heated at 180° C. for 1 hour, and then water was removed to obtain a water-soluble polyamide resin 2 having a polyethylene oxide skeleton and a piperazine ring in the main chain. When the weight average molecular weight was measured in the same manner as in Synthesis Example 1, it was 70,000.

<Preparation of support having easy-adhesion layer>
100 parts by mass of a polyester adhesive (“Vylon” (registered trademark) 30SS (copolyester, manufactured by Toyobo Co., Ltd.) on a 250 μm thick “Lumirror” (registered trademark) T60 (polyester film, manufactured by Toray Industries, Inc.) and "Coronate" (registered trademark) L (polyvalent isocyanate, manufactured by Nippon Polyurethane Industry Co., Ltd.) 3 parts by mass solution) was applied using a bar coater so that the thickness after drying was 20 μm, It was dried at 90° C. for 10 minutes to form a support having an easy-adhesion layer.

<Preparation of photosensitive resin layer composition solution>
80 parts by weight of polyamide resin 1, 30 parts by weight of water and 30 parts by weight of ethanol are placed in a three-necked flask equipped with a stirring spatula and a cooling tube, and heated at 90 ° C. for 2 hours while stirring to remove polyamide resin 1. Dissolved. After cooling to 70° C., 1.5 parts by mass of glycidimethacrylate was added and stirred for 30 minutes. Furthermore, 20 parts by weight of glycerin dimethacrylate, 20 parts by weight of polyalkylene glycol (PEG200) diacrylate, 20 parts by weight of 2-acryloyloxyethyl-2-hydroxyethyl phthalic acid, 15 parts by weight of pentaerythritol polyoxyethylene ether, 2, 3 parts by mass of 2-dimethoxy-1,1-diphenylethan-1-one and 0.01 part by mass of hydroquinone monomethyl ether were added and stirred for 30 minutes to obtain a photosensitive resin layer composition solution.

<Preparation of Infrared Sensitive Layer Composition Dispersion>
Preparation Example 1: Infrared Sensitive Layer Composition Dispersion 1
20 parts by weight of a 5% by weight aqueous solution of polyvinyl alcohol JL-22E (manufactured by Nippon Acetate & Poval Co., Ltd., saponification degree 80%, average polymerization degree 2,200) and carbon black BONJET BLACK CW-1 (Orient Chemical Industry Co., Ltd. ), containing carboxyl group and lactone group) and 10 parts by weight of a 10% by weight aqueous dispersion of "Solmix" (registered trademark) H-11 (alcohol mixture, manufactured by Nippon Alcohol Co., Ltd.) 5 parts by weight at room temperature were added and mixed to obtain an infrared-sensitive layer composition 1 dispersion. The dispersibility of the carbon black in the dispersion liquid of the infrared-sensitive composition 1 was good, and no aggregates of 2 µm or more were confirmed by a grind gauge.

Preparation example 2:
20 parts by weight of a 5% by weight aqueous solution of polyvinyl alcohol JL-22R (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., saponification degree 80%, average polymerization degree 2,200) and “CAB-O-JET” (registered trademark) 200 ( 10 parts by weight of a 10% by weight aqueous dispersion of Cabot Corporation, containing a sulfo group) and 5 parts by weight of "Solmix" (registered trademark) H-11 (alcohol mixture, manufactured by Nippon Alcohol Co., Ltd.) were added at room temperature. and mixed to obtain an infrared-sensitive layer composition 1 dispersion. The dispersibility of the carbon black in the dispersion liquid of the infrared-sensitive composition 2 was good, and no aggregates of 2 µm or more were confirmed by a grind gauge.

<Preparation of intermediate layer composition solution>
Preparation Example 3: Intermediate Layer Composition Solution 1
Polyamide resin 1 10 parts by mass obtained in Synthesis Example 1, 45 parts by mass of water, "Solmix" (registered trademark) H-11 (alcohol mixture, manufactured by Nippon Alcohol Co., Ltd.) 45 parts by mass at 70 ° C. 2 The solution was dissolved by stirring for hours, and an aqueous polyamide solution 1 was obtained. The polyamide aqueous solution 1 was used as the intermediate layer composition solution 1 .

Preparation Example 4: Intermediate layer composition solution 2
A polyamide aqueous solution 2 was obtained in the same manner as in Preparation Example 3, except that the polyamide resin 2 obtained in Synthesis Example 2 was used instead of the polyamide resin 1. The polyamide aqueous solution 2 was used as the intermediate layer composition solution 2 .

Preparation Example 5: Intermediate layer composition solution 3
Polyvinyl alcohol JL-22E with a degree of saponification of 80% and an average degree of polymerization of 2,200 (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd.), 45 parts by weight of water, and 45 parts by weight of "Solmix" H-11 are mixed at 70°C for 2 hours. The solution was dissolved by stirring, and a polyvinyl alcohol aqueous solution 1 was obtained. The polyvinyl alcohol aqueous solution 1 was used as the intermediate layer composition solution 3 .

Preparation Example 6: Intermediate Layer Composition Solution 4
Polyvinyl alcohol KL-03 (manufactured by Mitsubishi Chemical Corporation) having a degree of saponification of 80% and an average degree of polymerization of 300, 45 parts by weight of water, and 45 parts by weight of "Solmix" H-11 are stirred at 70°C for 2 hours to dissolve. , a polyvinyl alcohol aqueous solution 2 was obtained.

15 parts by weight of the polyvinyl alcohol aqueous solution 2 obtained and 85 parts by weight of the polyamide aqueous solution 1 obtained in Preparation Example 3 were mixed at room temperature to obtain an intermediate layer composition solution 4 .

Preparation Example 7: Intermediate Layer Composition Solution 5
50 parts by weight of the aqueous polyamide solution 2 obtained in Preparation Example 4 and 50 parts by weight of the aqueous polyvinyl alcohol solution 2 obtained in Preparation Example 6 were mixed at room temperature to obtain an intermediate layer composition solution 5 .

Evaluation methods in Examples and Comparative Examples are shown below.

<Number of Defects in the Infrared-Sensitive Layer in the Protective Layer/Infrared-Sensitive Layer Laminate>
A range of 30 cm × 30 cm from the infrared-sensitive layer/protective layer laminate, which is an intermediate obtained in each example and comparative example, was magnified using a magnifier and observed. defects) were counted. The smaller the number, the better the dispersibility of carbon black in the infrared-sensitive layer.

<Adhesion between photosensitive resin layer/infrared sensitive layer>
The protective layer was peeled off from the printing plate precursor obtained in each of Examples and Comparative Examples, and a multi-cutter guide was used on the heat-sensitive infrared layer with a cutter knife to form 25 squares of 2 mm width, 6 vertical x 6 horizontal. A cross-cut surface was made. Next, a 15 mm wide "Cellotape" (registered trademark) (manufactured by Nichiban Co., Ltd., CT405AP-15) was attached to the cross-cut surface so as not to trap air bubbles, and after 5 minutes, the tape was instantaneously peeled off. Based on the peeling state of the infrared-sensitive layer, the adhesion between the photosensitive resin layer and the infrared-sensitive layer was evaluated according to the following criteria.
0: Peeling is not observed.
1: Less than 5% of peeled area 2: 5% or more and less than 15% of peeled area 3: 15% or more and less than 35% of peeled area 4: 35% or more and less than 65% of peeled area 5: 65% or more of peeled area.

[Example 1]
The photosensitive resin layer composition solution was cast on the easy-adhesion layer of the support having the easy-adhesion layer obtained by the above method, dried at 60° C. for 2 hours, and dried to a thickness of 680 μm (support having the easy-adhesion layer). A photosensitive resin layer having a thickness of 950 μm including the body was formed. The thickness of the photosensitive resin layer was adjusted by placing a spacer with a predetermined thickness on a support having an easy-adhesion layer, and scraping out the protruding portion of the photosensitive resin layer composition solution with a horizontal metal ruler.

The infrared-sensitive layer composition 1 obtained by the method described above was dispersed on a 100 μm thick “Lumirror” (registered trademark) S10 (polyester film, manufactured by Toray Industries, Inc.) as a protective layer using a bar coater. The liquid was applied and dried at 120° C. for 30 seconds to form an infrared-sensitive layer to obtain a protective layer/infrared-sensitive layer laminate. The thickness of the infrared-sensitive layer is determined by optical density using an orthochromatic filter with the value of the protective layer set to zero (transmission mode of a Macbeth transmission densitometer "TR-927" (manufactured by Kollmorgen Instruments Corp.)). was adjusted to 3.0.

Next, intermediate layer composition solution 1 obtained by the method described above was applied on the infrared-sensitive layer of the protective layer/infrared-sensitive layer laminate using a bar coater so that the film thickness after drying was 1.0 μm. and dried at 120° C. for 30 seconds to form an intermediate layer to obtain an intermediate layer/infrared sensitive layer/protective layer.

A mixed solvent of 50 parts by mass of water/50 parts by mass of ethanol is applied onto the photosensitive resin layer formed by the above-described method, and the intermediate layer/infrared-sensitive layer/protective layer laminate is formed so that the intermediate layer side is on the photosensitive resin layer. A printing plate precursor was obtained by laminating so as to Table 1 shows the results of evaluation by the method described above.

[Example 2]
A printing plate precursor was obtained in the same manner as in Example 1, except that the infrared-sensitive layer was formed from the infrared-sensitive layer composition 2 dispersion. Table 1 shows the evaluation results.

[Examples 3 to 5]
Printing plate precursors were obtained in the same manner as in Example 1, except that the intermediate layer was formed from intermediate layer composition solutions 2, 4 and 5. Table 1 shows the evaluation results.

[Example 6]
In the same manner as in Example 1, a laminate of a protective layer/infrared-sensitive layer laminate was obtained.

Next, the intermediate layer composition solution 5 was applied onto the infrared-sensitive layer of the protective layer/infrared-sensitive layer laminate using a bar coater so that the film thickness after drying was 1.0 μm, and the coating was carried out at 120°C. After drying for 30 seconds, intermediate layer 2 was formed to obtain intermediate layer 2/infrared sensitive layer/protective layer. Furthermore, the intermediate layer composition solution 4 was applied onto the intermediate layer 2 of the intermediate layer 2/infrared-sensitive layer/protective layer using a bar coater so that the film thickness after drying was 1.0 μm, and the temperature was maintained at 120°C. and dried for 30 seconds to form an intermediate layer 1 to obtain an intermediate layer 1/intermediate layer 2/infrared sensitive layer/protective layer.

A mixed solvent of 50 parts by mass of water/50 parts by mass of ethanol is applied onto the photosensitive resin layer formed by the method described above to form an intermediate layer 1/intermediate layer 2/infrared-sensitive layer/protective layer laminate. A printing plate precursor was obtained by laminating so that the side was on the photosensitive resin layer. Table 1 shows the results of evaluation by the method described above.

[Comparative Example 1]
In the same manner as in Example 1, a laminate of a protective layer/infrared-sensitive layer laminate was obtained.

A mixed solvent of 50 parts by mass of water/50 parts by mass of ethanol is applied onto the photosensitive resin layer formed by the above method, and the infrared-sensitive layer/protective layer laminate is formed so that the infrared-sensitive layer side is on the photosensitive resin layer. A printing plate precursor was obtained by laminating in the same manner as above. Table 1 shows the results of evaluation by the method described above.

[Comparative Example 2]
A printing plate precursor was obtained in the same manner as in Example 1, except that the intermediate layer was formed from the intermediate layer composition solution 3. Table 1 shows the evaluation results.

Claims (5)

A photosensitive resin printing plate precursor having, on a support, a photosensitive resin layer containing a polyamide resin having a polyether structure, an intermediate layer and an infrared-sensitive layer in this order, wherein the infrared-sensitive layer has a saponification degree of 60 to 100 mol. A photosensitive resin printing plate precursor containing polyvinyl alcohol having an average polymerization degree of 300 to 3,000% and an intermediate layer containing a polyamide resin having basic nitrogen atoms and/or polyether structural units. 2. The photosensitive resin printing plate according to claim 1, which has two or more intermediate layers, wherein the intermediate layer on the infrared-sensitive layer side contains polyvinyl alcohol having a saponification degree of 60 to 100 mol % and an average polymerization degree of 300 to 3,000. Original version. The photosensitive resin printing plate precursor according to Claim 1 or 2, wherein the polyamide resin containing a basic nitrogen atom has a piperazine ring. 2. The photosensitive resin printing plate precursor according to claim 1, wherein the infrared-sensitive layer contains carbon black having a carboxyl group and/or a sulfo group. 5. The photosensitive resin printing plate precursor according to claim 4, wherein said carbon black has a carboxyl group and a lactone group.