JP2019032402A - Photosensitive resin composition for letterpress printing original plate and letterpress printing original plate using the same - Google Patents

Abstract

An object of the present invention is to provide an excellent image reproducibility without lack of highlight halftone dots even when developed with a hard brush while maintaining printing durability, and to increase the compounding ratio of a tertiary nitrogen atom-containing polyamide. Provided is a photosensitive resin composition for a letterpress printing original plate, which does not increase surface tackiness even when used. (i) modified partially saponified polyvinyl acetate having a functional group introduced into the side chain, (ii) a tertiary nitrogen atom-containing polyamide, (iii) a photopolymerizable unsaturated compound, and (iv) photopolymerization A photosensitive resin composition for letterpress printing original plates containing an initiator, wherein (ii) a tertiary nitrogen atom-containing polyamide is an aminocarboxylic acid unit in a polyamide molecule (including the case of a lactam as a raw material), a dicarboxylic acid It contains 20 to 50 mol % of structural units obtained from cyclohexanedicarboxylic acid and 50 to 95 mol % of alicyclic structural units in total relative to the total of units and diamine units. [Selection figure] None

Description

  The present invention relates to a partially saponified polyvinyl acetate-containing photosensitive resin composition for letterpress printing and a letterpress printing original plate using the same, and more specifically, while maintaining printing durability, particularly an increase in printing plate surface adhesion. The present invention relates to a photosensitive resin composition capable of obtaining a printing original plate with a reduced print quality and improved printing quality, and a relief printing original plate using the same.

  The printing original plate for letterpress printing contains a soluble polymer compound, a photopolymerizable unsaturated compound, and a photopolymerization initiator as essential components in a photosensitive resin layer, and additives such as a stabilizer and a plasticizer are blended. It is common. Then, such a printing original plate is formed by irradiating the photosensitive resin layer with ultraviolet light through an image mask layer opaque to ultraviolet light, thereby forming a solvent-soluble portion and a portion not in the photosensitive resin layer, In general, a solvent-dissolved portion is washed away to form a relief image and used as a printing plate.

  A relief printing original plate comprising a photosensitive resin layer is mainly used to form a relief by developing a relief image formed by exposure to water, and as a soluble polymer compound of the photosensitive resin layer, water-soluble or water-soluble Swellable polymer compounds are used.

  Partially saponified polyvinyl acetate has been used as a photosensitive resin for letterpress printing original plates because of its excellent water developability. However, when a hard brush is used during water development, there is a problem in that highlight dots are missing. there were. In addition, due to the brittleness against the printing pressure applied during printing, there is a problem in that cracks are easily generated in the relief during long run printing, and the printing plate must be replaced.

  In order to solve these problems, a combination of a polyvinyl acetate derivative and a tertiary nitrogen atom-containing polyamide has been proposed as a soluble polymer compound (see Patent Documents 1 and 2). Although this method improves crack resistance, it has a new problem that the tackiness of the printing plate surface increases due to the tackiness of the polyamide itself.

  In addition, modified partially saponified polyvinyl acetate and tertiary nitrogen atom-containing polyamide were used as the soluble polymer compound, and further, a photopolymerizable unsaturated compound having a specific 5- to 7-membered ring was used. The thing is proposed (refer patent document 3). Although this method was able to further improve the printing durability, the tackiness of the printing plate surface derived from the tertiary nitrogen atom-containing polyamide has not been solved.

JP-A-11-65115 JP 2001-227776 A WO2014 / 021322

  The present invention was devised in order to solve such problems of the prior art, and its purpose is to maintain excellent printing durability while maintaining excellent highlight halftone dots even when developed with a hard brush. Photosensitive resin composition for letterpress printing original plate that has image reproducibility and does not increase surface adhesion even when the compounding ratio of tertiary nitrogen atom-containing polyamide is increased, and letterpress printing original plate using the same Is to provide.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have determined that, among the photosensitive resin compositions used for the relief printing original plate, as tertiary nitrogen atom-containing polyamides, aminocarboxylic acid units ( A tertiary nitrogen atom containing a specific amount of a structural unit and an alicyclic structural unit obtained from cyclohexanedicarboxylic acid with respect to the total of dicarboxylic acid units and diamine units) By using the containing polyamide, while maintaining the printing durability, it has high highlight halftone dot image reproducibility without chipping during development, and also increases the blending ratio of the tertiary nitrogen atom-containing polyamide. In addition, the present inventors have found that it is possible to provide a material that does not increase the tackiness of the printing plate surface, and have completed the present invention.

The present invention has been completed based on the above findings, and has the following configurations (1) to (6).
(1) (i) modified partially saponified polyvinyl acetate having a functional group introduced in the side chain, (ii) tertiary nitrogen atom-containing polyamide, (iii) photopolymerizable unsaturated compound, and (iv) initiation of photopolymerization A photosensitive resin composition for letterpress printing original plate containing an agent, wherein (ii) the tertiary nitrogen atom-containing polyamide is an aminocarboxylic acid unit (including lactam as a raw material) in a polyamide molecule, a dicarboxylic acid unit And a total of 50 to 95 mol% of structural units obtained from cyclohexanedicarboxylic acid and 50 to 95 mol% of alicyclic structural units based on the total of diamine units. Photosensitive resin composition for printing original plate.
(2) In the photosensitive resin composition for letterpress printing original plate, (i) modified partially saponified polyvinyl acetate having a functional group introduced in the side chain, (ii) tertiary nitrogen atom-containing polyamide, (iii) photopolymerizability The use amount of the unsaturated compound and (iv) photopolymerization initiator is 30 to 65% by mass, 5 to 30% by mass, 5 to 25% by mass, and 0.1 to 5% by mass, respectively. The photosensitive resin composition for letterpress printing original plates as described in (1).
(3) The photosensitive resin composition for letterpress printing original plate as described in (1) or (2), wherein the (ii) tertiary nitrogen atom-containing polyamide is a polyamide containing a piperazine ring in the molecule. object.
(4) The modified partially saponified polyvinyl acetate having a functional group in the side chain (i) contains an ester bond and a functional group in the side chain, and the functional group is a photopolymerizable unsaturated group and / or Or it is a carboxyl group, The photosensitive resin composition for letterpress printing original plates in any one of (1)-(3) characterized by the above-mentioned.
(5) In any one of (1) to (4), the (iii) photopolymerizable unsaturated compound contains a heterocyclic-containing photopolymerizable unsaturated compound having a 5- to 7-membered ring. The photosensitive resin composition for letterpress printing original plates as described.
(6) A letterpress printing original plate comprising a photosensitive resin layer formed using the photosensitive resin composition for letterpress printing original plate according to any one of (1) to (5) on a support.

  According to the photosensitive resin composition for a relief printing original plate of the present invention, high highlight halftone dot image reproducibility and printing durability can be maintained, and the tertiary nitrogen atom-containing polyamide content can be increased. It is possible to obtain a relief printing original plate in which the tackiness of the printing plate surface does not increase.

  Hereinafter, the photosensitive resin composition for a relief printing original plate of the present invention and the relief printing original plate using the same will be described.

  The photosensitive resin composition for a relief printing original plate according to the present invention comprises (i) a modified partially saponified polyvinyl acetate having a functional group introduced into a side chain, (ii) a tertiary nitrogen atom-containing polyamide, and (iii) photopolymerizability. By using an unsaturated compound, and (iv) a photopolymerization initiator, and (ii) a tertiary nitrogen atom-containing polyamide containing a specific structural unit in a specific ratio, Highlight dot image reproducibility and printing durability while maintaining the adhesiveness of the printing plate surface, which is a disadvantage of the conventional tertiary nitrogen atom-containing polyamide, can be effectively prevented. And

  (I) Modified partially saponified polyvinyl acetate having a functional group introduced into a side chain (hereinafter also referred to as component (i)) is a modified partially saponified polyvinyl acetate containing a functional group in the side chain. This functional group can be a photopolymerizable unsaturated group and / or a carboxyl group. Here, the photopolymerizable unsaturated group is a radical-reactive crosslinkable functional group, and a (meth) acryloyl group is preferable. As the functional group, a photopolymerizable unsaturated group or a carboxyl group may be introduced alone, or both a photopolymerizable unsaturated group and a carboxyl group may be introduced. Water resistance can be improved by introducing a photopolymerizable unsaturated group. Further, by introducing a carboxyl group, compatibility can be improved by quaternary chlorination with a tertiary nitrogen atom-containing polyamide. Furthermore, since the functional group has an ester bond, (iii) compatibility with the photopolymerizable unsaturated compound can be improved, and the photocrosslinking reaction can be performed efficiently. In particular, when both a photopolymerizable unsaturated group and a carboxyl group are introduced, it is possible to reduce relief chipping during development and to improve compatibility with a tertiary nitrogen atom-containing polyamide.

  As a method of introducing a carboxyl group into the side chain of the modified partially saponified polyvinyl acetate, a method of introducing a carboxyl group into the polymer side chain by reacting a hydroxyl group and an acid anhydride in the partially saponified polyvinyl acetate, Examples thereof include a method of introducing a carboxyl group into a side chain by partially saponifying a polymer obtained by copolymerizing vinyl acetate and an unsaturated carboxylic acid or a salt thereof, or an unsaturated carboxylic acid ester. The side chain of the modified partially saponified polyvinyl acetate obtained by these methods also contains an ester bond, which is more preferable from the viewpoint of (iii) compatibility with the photopolymerizable unsaturated compound. Further, the modified partially saponified polyvinyl acetate obtained by this method is preferable because the introduction of a reactive group is easy and the effects of the present invention are remarkably exhibited.

  As a method for introducing a photopolymerizable unsaturated group into a side chain of a modified partially saponified polyvinyl acetate, a modified partially saponified polyvinyl acetate having a carboxyl group introduced into the side chain is used. The method of introduce | transducing a reactive group can be mentioned by making the carboxyl group in it react and the photopolymerizable unsaturated group containing epoxy compound. The side chain of the modified partially saponified polyvinyl acetate obtained by this method also contains an ester bond, which is more preferable from the viewpoint of (iii) compatibility with the photopolymerizable unsaturated compound. Further, the modified partially saponified polyvinyl acetate obtained by this method is preferable because the introduction of a reactive group is easy and the effects of the present invention are remarkably exhibited.

  As another method for introducing a photopolymerizable unsaturated group into the modified partially saponified polyvinyl acetate, the reaction of the partially saponified polyvinyl acetate with an acrylic compound having an N-methylol group results in the reaction of the partially saponified polyvinyl acetate. Examples thereof include a method for introducing a reactive group into the side chain. As specific manufacturing conditions, if the reaction is carried out in the range of 5 to 30 parts by mass of an acrylic compound with 100 parts by mass of partially saponified polyvinyl acetate, it is possible to achieve both reduction of relief chipping during development and water developability. It is preferable. As the acrylic compound having an N-methylol group, N-methylolacrylamide and N-methylolmethacrylamide are particularly preferable. These may be used alone or in combination of two or more.

  The amount of the functional group introduced into the side chain of the modified partially saponified polyvinyl acetate is preferably 0.1 to 0.7 mol / kg in the modified partially saponified polyvinyl acetate. When the amount is more than 0.7 mol / kg, the water solubility may be deteriorated, and when the amount is less than 0.1 mol / kg, the improvement effect may be hardly exhibited.

  The saponification degree of the modified partially saponified polyvinyl acetate is preferably in the range of 60 to 95 mol%, more preferably in the range of 70 to 90 mol%. If the saponification degree is less than the above range, the water developability may decrease due to the decrease in hydrophilicity. If the saponification degree exceeds the above range, the water developability may decrease due to excessive crystallinity. There is a risk.

  The average degree of polymerization of the modified partially saponified polyvinyl acetate is preferably in the range of 200 to 1500, more preferably in the range of 500 to 1000. When the average degree of polymerization is less than the above range, the water resistance may be lowered, and when the average degree of polymerization exceeds the above range, the water developability may be lowered.

  The usage-amount of (i) component in the photosensitive resin composition of this invention becomes like this. Preferably it is 30-65 mass%, More preferably, it is 35-65 mass%, More preferably, it is 40-60 mass%. When the amount of the component (i) used is less than the above range, the form-retaining property of the photosensitive resin layer is low and the handling property may be inferior, and when it exceeds the above range, the water developability may be deteriorated.

  (Ii) Tertiary nitrogen atom-containing polyamide (hereinafter also referred to as component (ii)) is a total of aminocarboxylic acid units (including lactam as a raw material), dicarboxylic acid units, and diamine units in the polyamide molecule. On the other hand, the structural unit obtained from cyclohexane dicarboxylic acid is contained in an amount of 20 to 50 mol%, and the alicyclic structural unit is contained in a total of 50 to 95 mol%. The alicyclic structural unit here naturally includes a structural unit obtained from cyclohexanedicarboxylic acid.

  The component (ii) used in the present invention contains specific amounts of structural units and alicyclic structural units obtained from cyclohexanedicarboxylic acid as described above, and therefore, during development, which often occurs due to the blending of component (i) This can improve the problem of missing halftone dots and missing relief during printing. Furthermore, even if the amount of the tertiary nitrogen atom-containing polyamide (ii) is increased, the tackiness of the printing plate surface increases. There is an effect that there is little to do. Therefore, according to the present invention, the conventional tertiary nitrogen atom-containing polyamide is easy to absorb moisture, and it is possible to increase the amount of addition which was impossible due to high adhesiveness. The effect can be enhanced.

  The component (ii) is not only alicyclic dicarboxylic acid including cyclohexanedicarboxylic acid, alicyclic diamine, and tertiary nitrogen atom-containing diamine, but also diamine, dicarboxylic acid, ω-amino acid, lactam, etc. It can be obtained by polymerizing the body together as a raw material.

  As described above, cyclohexanedicarboxylic acid is a structure obtained from cyclohexanedicarboxylic acid with respect to the total of aminocarboxylic acid units (including lactam as a raw material), dicarboxylic acid units, and diamine units in the polyamide molecule. It is used in such an amount that the unit is 20 to 50 mol%. When the proportion of the structural unit obtained from cyclohexanedicarboxylic acid is less than the above range, the surface adhesion of the printing plate increases, and when it exceeds the above range, the effect of improving the printing durability is small.

  Cyclohexanedicarboxylic acid is a dicarboxylic acid containing a cyclohexane ring. Specifically, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 2-methyl- 1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, 2-propyl-1,4-cyclohexanedicarboxylic acid, 2-butyl-1,4-cyclohexanedicarboxylic acid, 2-t-butyl- 1,4-cyclohexanedicarboxylic acid, 2,3-dimethyl-1,4-cyclohexanedicarboxylic acid, 2,3-diethyl-1,4-cyclohexanedicarboxylic acid, 2,3-dipropyl-1,4-cyclohexanedicarboxylic acid, 2,3-dibutyl-1,4-cyclohexanedicarboxylic acid, 2-methyl Ru-3-ethyl-1,4-cyclohexanedicarboxylic acid, 2-methyl-3-propyl-1,4-cyclohexanedicarboxylic acid, 2-methyl-3-butyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl- Examples include 3-propyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-3-butyl-1,4-cyclohexanedicarboxylic acid, and 2-methyl-3-t-butyl-1,4-cyclohexanedicarboxylic acid. Among these, 1,4-cyclohexanedicarboxylic acid is preferable in terms of reproducibility of gradation printability in the highlight portion.

  As described above, the component (ii) contains 50 alicyclic structural units in total with respect to the total of aminocarboxylic acid units (including lactam as a raw material), dicarboxylic acid units, and diamine units in the polyamide molecule. Contains ~ 95 mol%. In addition to cyclohexanedicarboxylic acid, alicyclic structural units also include structural units obtained from alicyclic dicarboxylic acids and, if necessary, alicyclic diamines and alicyclic aminocarboxylic acids. When the total content of the alicyclic structural units is less than the above range, the compatibility with the component (i) is inferior, and therefore the amount of the component (ii) cannot be increased. On the other hand, when it exceeds the above range, the printing durability is inferior.

  Examples of the alicyclic dicarboxylic acid other than the above-mentioned cyclohexanedicarboxylic acid include isophorone dicarboxylic acid, 2,3-norbornane dicarboxylic acid, 2,6-decalin dicarboxylic acid, 3-methyl-2,6-decalin dicarboxylic acid, 3- Ethyl-2,6-decalin dicarboxylic acid, 3-propyl-2,6-decalin dicarboxylic acid, 3-butyl-2,6-decalin dicarboxylic acid, 3,4-dimethyl-2,6-decalin dicarboxylic acid, 3, 4-diethyl-2,6-decalin dicarboxylic acid, 3,4-dipropyl-2,6-decalin dicarboxylic acid, 3,4-dibutyl-2,6-decalin dicarboxylic acid, 3,8-dimethyl-2,6- Decalin dicarboxylic acid, 3,8-diethyl-2,6-decalin dicarboxylic acid, 3,8-dipropyl-2,6-decalin dicarboxylic acid 3,8-dibutyl-2,6-decalin dicarboxylic acid, 3-methyl-4-ethyl-2,6-decalin dicarboxylic acid, 3-methyl-4-propyl-2,6-decalin dicarboxylic acid, 3-methyl Examples include -4-butyl-2,6-decalin dicarboxylic acid and 3-ethyl-4-butyl-2,6-decalin dicarboxylic acid.

  Examples of the alicyclic diamine include isophorone diamine, 1,4-cyclohexane diamine, 1,3-cyclohexane diamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane. 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, bis (4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, 2,2-bis (4-amino) (Cyclohexyl) propane, 1,4-bis (3-aminopropyl) piperazine, N- (2-aminoethyl) piperazine, methylcyclohexanediamine, norbornanediamine, and tricyclodecanediamine. Among these, isophoronediamine and 1,3-bis (aminomethyl) cyclohexane are preferable from the viewpoint of compatibility with the component (i).

  Examples of the alicyclic aminocarboxylic acid include 4-aminocyclohexanecarboxylic acid, 3-aminocyclohexanecarboxylic acid, 4- (aminomethyl) cyclohexanecarboxylic acid, 3- (aminomethyl) cyclohexanecarboxylic acid, and 2-amino. And methylcyclopropanecarboxylic acid.

  The component (ii) used in the present invention is a polyamide containing a tertiary nitrogen atom in the molecule, specifically, a part of the main chain or side chain, and a monomer having a tertiary nitrogen atom. It can be obtained by performing condensation polymerization, polyaddition reaction or the like. The tertiary nitrogen atom is preferably a piperazine ring or an N, N-dialkylamino group, more preferably a piperazine ring. Examples of the monomer having a tertiary nitrogen atom for producing the component (ii) include aliphatic diamines containing a tertiary nitrogen atom such as a diamine having a piperazine ring and methyliminobispropylamine. Examples of the diamine having a piperazine ring include N, N′-bis (aminoethyl) -piperazine, N, N′-bis (3-aminopropyl) piperazine, and N, N′-di (aminopentyl) piperazine. Of these, N, N′-bis (3-aminopropyl) piperazine is preferred. Also, ω-amino acids such as N, N′-dimethyl-N- (aminomethyl) -N ′-(carboxymethyl) -ethylenediamine can be used.

  The amount of component (ii) used in the photosensitive resin composition of the present invention is preferably 5 to 30% by mass, and more preferably 8 to 25% by mass. If the amount of component (ii) used is less than the above range, the brush chip resistance, image reproducibility and printing durability may be inferior. If the amount exceeds the above range, the amount of partially saponified polyvinyl acetate will decrease. Therefore, there is a possibility that the original form retainability may be impaired. In particular, in the present invention, even if the amount of the component (ii) is increased to 8% by mass or more in the photosensitive resin composition, the problem of increase in the tackiness of the printing plate surface does not stand out. Therefore, the effect of compounding the component (ii) into the photosensitive resin composition for letterpress printing original plate can be further enhanced by increasing the amount used.

  (Iii) As the photopolymerizable unsaturated compound (hereinafter also referred to as (iii) component), those conventionally used by those skilled in the art in this technical field can be used. For example, it has a 5- to 7-membered ring. It is preferable to contain a heterocycle-containing photopolymerizable unsaturated compound. The heterocyclic-containing photopolymerizable unsaturated compound having a 5- to 7-membered ring preferably has at least a functional group such as a hydroxyl group, a carboxyl group, or an amino group in the heterocyclic ring. Since the heterocyclic ring and the functional group hydrogen bond with the hydroxyl group in the component (i), compatibility with the component (i) can be increased. The heterocyclic-containing photopolymerizable unsaturated compound having a 5- to 7-membered ring preferably has a molecular weight of 300 or less. When the molecular weight increases, the compatibility with the component (i) may be reduced.

  Examples of the component (iii) include benzyl (meth) acrylate, cyclohexyl (meth) acrylate, phenoxymethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, and 2- (meth) acryloyl. Roxyethyl hexahydrophthalic acid, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl phthalic acid, neopentyl glycol- (meth) acrylic acid-benzoic acid ester, (meth) acryloyl Morpholine, styrene and its derivatives, vinyl pyridine, N-vinyl-2-pyrrolidone, β- (meth) acryloyloxyethyl hydrogen phthalate, N-phenylmaleimide and its derivatives, N- (meth) Heterocyclyloxy succinimide, and the like can be used (meth) acrylic acid-2-naphthyl, N- phenyl (meth) acrylamide.

  The amount of component (iii) used in the photosensitive resin composition of the present invention is preferably 5 to 25% by mass, and more preferably 8 to 20% by mass. If the amount of component (i) used is less than the above range, the image reproducibility may be insufficient, and if it exceeds the above range, the photosensitive resin layer used for the relief printing original plate may be difficult to solidify.

  (Iv) The photopolymerization initiator (hereinafter also referred to as component (iv)) has an effect of generating radicals by light absorption. As the component (iv), conventionally known components can be used, and examples thereof include benzoin alkyl ethers, benzophenones, anthraquinones, benzyls, acetophenones, and diacetyls. It is preferable that the usage-amount of the (iv) component in the photosensitive resin composition of this invention is 0.1-5 mass%.

  Arbitrary components, such as a plasticizer and a polymerization inhibitor, can further be blended in the photosensitive resin composition of the present invention. The plasticizer is for enhancing flexibility, and specific examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, glycerin and derivatives thereof, trimethylolpropane and derivatives thereof, trimethylolethane and derivatives thereof, pentaerythritol. And polyhydric alcohols such as derivatives thereof. It is preferable that the usage-amount of these plasticizers is 20 mass% or less of the mass of the whole photosensitive resin composition of this invention. The polymerization inhibitor is for increasing the thermal stability, and specific examples thereof include phenols, hydroquinones, catechols, hydroxyamine derivatives and the like. It is preferable that the usage-amount of these polymerization inhibitors is 0.001-5 mass% of the mass of the whole photosensitive resin composition of this invention.

  Furthermore, optional components such as dyes, pigments, surfactants, antifoaming agents, ultraviolet absorbers, and fragrances can be blended at a ratio of up to 10% by mass of the photosensitive resin composition.

  The photosensitive resin composition for letterpress printing original plate of the present invention is appropriately mixed using the above essential components (i) to (iv) and optional components, and using the melt molding method, for example, An original plate for letterpress printing provided with a photosensitive resin layer can be obtained by forming into a desired laminate structure by a known method such as hot pressing, casting, melt extrusion, or solution casting.

  The relief printing original plate can be used by laminating a molded product (unexposed resin) formed into a sheet shape on a support with or without a known adhesive. As the support, conventionally known ones such as steel, aluminum, glass, plastic films such as polyester film can be used, and generally a film having a thickness in the range of 50 to 500 μm is used. When supplying a sheet-like molded article (unexposed resin) as a laminate laminated on a support, it is preferable to further laminate a protective film in contact with the sheet-like molded article (unexposed resin). As the protective film, a film-like plastic can be used. For example, a polyester film having a thickness of 125 μm is used. Moreover, you may provide the anti-adhesion layer which apply | coated the polymer which disperse | distributes or melt | dissolves in a developing solution transparently without adhesiveness with the thickness of 0.5-3 micrometers between the photosensitive resin layer and a protective film. By providing an anti-adhesion layer on the surface of the photosensitive resin layer, the protective layer can be easily peeled off during the next exposure operation even when the surface adhesiveness is strong.

  In the relief printing original plate of the present invention, a cap layer having a thickness of 1 to 30 μm may be provided between the photosensitive resin layer and the anti-adhesion layer. Since the cap layer is not removed in the development step and remains on the printing plate, the surface properties and durability of the printing plate can be adjusted by providing the cap layer. As the cap layer, a conventionally known cap layer can be used as it is.

  The relief printing original plate of the present invention can produce a CTP (Computer to Plate) plate that does not use a negative film by providing a heat-sensitive mask layer on the surface of the photosensitive resin layer. As the heat sensitive mask layer, a conventionally known heat sensitive mask layer can be used as it is.

  The relief printing original plate obtained from the photosensitive resin composition for relief printing original plate according to the present invention has a negative film having a transparent image portion in close contact with the photosensitive resin layer, and is exposed by irradiation with actinic rays from above. To prepare an original plate in which only the exposed portion through which the actinic ray is transmitted is insolubilized. As the active light, a light source such as a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, a xenon lamp, or a chemical lamp, usually centered on a wavelength of 300 to 450 nm, is used.

  On the other hand, in the case of the CTP plate, the heat-sensitive mask layer is irradiated like an image with an IR laser to form a mask (the same function as a negative film) on the photosensitive resin layer. After the image information is written on the heat-sensitive mask layer, the photosensitive printing original plate is irradiated with the actinic ray through the mask to produce an original plate in which only the exposed portion through which the actinic ray is transmitted is insolubilized.

  Next, the non-exposed portion is dissolved and removed with a suitable solvent, particularly neutral water in the present invention, but it is preferable to dissolve and remove the non-exposed portion by a developing method such as a spray type developing device or a brush type developing device. Thereafter, the printing plate from which the non-exposed portion has been dissolved and removed is subjected to draining, drying, and post-exposure steps to obtain a final printing plate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these. In the examples (text), the number of parts represents parts by mass, and the polyamide composition in Table 1 represents mol%. The mol% of the polyamide composition was determined by H-NMR measurement. In addition, evaluation of the characteristic value in an Example depended on the following method.

(1) 30 μm fine wire brush resistance resistance First, using a negative printing plate with a photosensitive resin layer thickness of 685 μm using a negative containing a 30 μm fine wire as an image, and using a chemical lamp with an illuminance adjusted to 25 W / m ² The film was exposed for 8 minutes from a distance of 5 cm from the surface of the photosensitive resin layer. Next, using a brush type washer (JW-A2-PD type produced by JEOL Ltd.), development was performed with tap water at 25 ° C. using nylon brushes of several different diameters to obtain a relief image. The plate was further dried with hot air at 60 ° C. for 10 minutes, and then post-exposed with an ultrahigh pressure mercury lamp for 30 seconds to obtain a printing plate. The reproducibility of 30 μm fine lines was observed with a microscope magnified 50 times and evaluated according to the following criteria.
A: The brush diameter is 200 μm, and the thin line is not chipped.
○: The brush diameter is 150 μm, and there is no chipping in the thin line.
(Triangle | delta): A brush diameter is 120 micrometers and there is no chipping in a thin line.
X: Chipping is observed in the thin line even with a brush diameter of 120 μm.

(2) Adhesiveness of printing plate surface First, a printing evaluation negative containing a solid image (width 1 cm × length 5 cm) as an image on a relief printing original plate having a photosensitive resin layer thickness of 685 μm, and an illuminance of 25 W / m Using a chemical lamp adjusted to ² , exposure was performed for 8 minutes from a distance of 5 cm from the surface of the photosensitive resin layer. Next, it developed with 25 degreeC tap water with the brush type washer (120 micrometer diameter nylon brush, JEOL Seiki Co., Ltd. product JW-A2-PD type | mold), and obtained the relief image. The plate was further dried with hot air at 60 ° C. for 10 minutes, and then post-exposed with an ultrahigh pressure mercury lamp for 30 seconds to obtain a printing plate. The obtained printing plate was used to evaluate the tackiness of the printing plate surface. The tackiness was evaluated according to the following criteria from the degree of slippage of the coated paper by pressing the coated paper (Gloss PW-8K, manufactured by Lintec Co., Ltd.), which is the printing material, against the plate.
A: Even if the coated paper is pressed against the plate 100 times or more, the coated paper slips without resistance.
○: The coated paper slides without resistance, but when the coated paper is pressed against the plate 100 times or more, a slight resistance is felt.
Δ: When the coated paper is pressed against the plate, the coated paper and the plate immediately adhere to each other. However, when power is applied, the coated paper slides.
X: When the coated paper is pressed against the plate, the coated paper and the plate are completely adhered and do not slip.

(3) Image reproducibility First, using a negative which contains a 200% 1% fine line as an image on a letterpress printing original plate having a photosensitive resin layer thickness of 685 μm, a chemical lamp having an illuminance adjusted to 25 W / m ² is used. The film was exposed for 8 minutes from a distance of 5 cm from the surface of the photosensitive resin layer. Next, using a brush type washer (JW-A2-PD type produced by JEOL Ltd.), development was performed with tap water at 25 ° C. using nylon brushes of several different diameters to obtain a relief image. The plate was further dried with hot air at 60 ° C. for 10 minutes, and then post-exposed with an ultrahigh pressure mercury lamp for 30 seconds to obtain a printing plate. The reproducibility of a 200% 1% halftone dot was observed with a microscope at 50 times magnification and evaluated according to the following criteria.
(Double-circle): A 200% 1% halftone dot is completely reproduced with a brush diameter of 200 μm.
○: A 200% 1% halftone dot is completely reproduced at a brush diameter of 150 μm.
Δ: A 200% 1% halftone dot is completely reproduced with a brush diameter of 120 μm.
X: A 200% 1% halftone dot is not reproduced even with a brush diameter of 120 μm.

(4) Printing durability A printing plate is produced by the same method as that for producing the relief for evaluating the adhesiveness of the printing plate surface described in (2) above, and 10,000 shots are obtained under a pressure of 50 μm from the appropriate printing pressure. Printing was performed, and after printing 10,000 shots, the printed matter and the plate were observed with a microscope magnified 200 times, and evaluated according to the following criteria.
(Double-circle): There is no fault in a printed matter and the plate does not have a crack in observation of the microscope expanded 200 times.
○: There is no defect in the printed matter by observation with a microscope magnified 200 times, but the plate has slight cracks.
(Triangle | delta): Although a fault cannot be confirmed visually with a printed matter or a plate, inferiority is seen in a printed matter or a plate by observation of the microscope expanded 200 times.
X: Defects can be confirmed visually on the printed matter or the plate.

<(I) Synthesis of Modified Partially Saponified Polyvinyl Acetate Introduced with Functional Group in Side Chain>
Synthesis example i-1:
Partially saponified polyvinyl acetate “KL-05” (polymerization degree: about 500, saponification degree: 80 mol%) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. is swollen in acetone, and 1.0 mol% of succinic anhydride is added. The mixture was stirred at 60 ° C. for 6 hours to add a carboxyl group to the molecular chain. The polymer was washed with acetone to remove unreacted succinic anhydride and dried. 100 parts of this polymer was dissolved at 80 ° C. in 200 parts of a mixed solvent of ethanol / water = 30/70 (mass ratio). 6 parts of glycidyl methacrylate was added thereto to introduce a reactive group into the partially saponified polyvinyl acetate. From the analysis result by potentiometric titration method, it was confirmed that the carboxyl group in the polymer reacted with the epoxy group of glycidyl methacrylate, and the methacryloyl group was introduced into the polymer side chain. Modified partially saponified polyvinyl acetate i-1 was introduced.

Synthesis example i-2:
A polymer containing 1 mol% of methacrylic acid as a copolymer unit in vinyl acetate was saponified to obtain an anion-modified polyvinyl acetate having an average polymerization degree of 650 and a saponification degree of 75 mol%. 100 parts of this polymer was dissolved at 80 ° C. in 200 parts of a mixed solvent of ethanol / water = 30/70 (mass ratio). 6 parts of glycidyl methacrylate was added thereto to introduce a reactive group into the partially saponified polyvinyl acetate. From the analysis result by potentiometric titration method, it was confirmed that the carboxyl group in the polymer reacted with the epoxy group of glycidyl methacrylate, and the methacryloyl group was introduced into the polymer side chain. Modified partially saponified polyvinyl acetate i-2 into which was introduced was obtained.

Synthesis example i-3:
100 parts of partially saponified polyvinyl acetate “KL-05” (polymerization degree: about 500, saponification degree: 80 mol%) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. is dissolved in 100 parts of water, and 15 parts of N-methylolacrylamide 1 part of phosphoric acid is added as an acid catalyst, and the mixture is stirred for 4 hours at 100 ° C. Vinyl acetate i-3 was obtained.

<(Ii) Synthesis of tertiary nitrogen atom-containing polyamide>
Synthesis example ii-1:
ε-caprolactam 521 parts (46.0 mol%), cyclohexanedicarboxylic acid 458 parts (26.6 mol%), 1,4-bis (3-aminopropyl) piperazine 549 parts (27.4 mol%), 50% 5 parts of hypophosphorous acid aqueous solution and 3000 parts of water were charged into an autoclave, and after nitrogen substitution, sealed and gradually heated. From the time when the internal pressure reached 0.4 MPa, water was distilled off until the pressure could not be maintained, the pressure was returned to normal pressure in about 2 hours, and then reacted at normal pressure for 1 hour. The maximum polymerization reaction temperature was 255 ° C. Thereby, tertiary nitrogen atom containing polyamide ii-1 which is (ii) component was obtained. The composition of the obtained tertiary nitrogen atom-containing polyamide was measured by H-NMR, and it was confirmed that there was no difference between the charged composition and the polymer composition. Table 1 shows the composition of this tertiary nitrogen atom-containing polyamide ii-1 and the proportions of structural units and alicyclic structural units obtained from cyclohexanedicarboxylic acid in the polyamide.

Synthesis examples ii-2 to ii-8
Synthesis was performed in the same manner as in Synthesis Example ii-1, except that the types and blending ratios of diamine and dicarboxylic acid and the blending ratio of ε-caprolactam were changed so that the polyamide composition shown in Table 1 was obtained. ) Tertiary nitrogen atom-containing polyamides ii-2 to ii-8 were obtained. The composition of the obtained tertiary nitrogen atom-containing polyamide was measured by H-NMR, and it was confirmed that there was no difference between the charged composition and the polymer composition. Table 1 shows the compositions of these tertiary nitrogen atom-containing polyamides ii-2 to ii-8 and the proportions of structural units and alicyclic structural units obtained from cyclohexanedicarboxylic acid in the polyamide.

Example 1
In a three-necked flask equipped with a stirring spatula and a condenser tube, the components (i) and (ii) shown in Table 2 were added, and “Solmix” (registered trademark) H-11 (alcohol mixture, Japanese alcohol) A mixed solvent of 50 parts and 50 parts of water was mixed and then heated at 90 ° C. for 2 hours with stirring to dissolve the components (i) and (ii). After cooling to 70 ° C., other components were added and stirred for 30 minutes to obtain a photosensitive resin composition.

  Next, a support having an adhesive layer was prepared. A support having an adhesive layer was obtained by coating an adhesive composition containing an ultraviolet absorber on a polyester film having a thickness of 250 μm with a coating thickness of 20 μm. Using the obtained support, the photosensitive resin composition described above was cast on the surface of the adhesive layer of this support, and a film of polyvinyl alcohol (AH-26, manufactured by Nippon Synthetic Chemical Co., Ltd.) having a thickness of 2 μm was formed. A raw plate of a sheet-like laminate having a total thickness of 1080 μm was molded using a laminator so that the coated side of the coated polyester film having a thickness of 125 μm was in contact with the photosensitive resin composition.

  After storing the printing plate for 7 days or more, the printing plate characteristics and printing durability were evaluated. These evaluation results are shown in Table 2 together with the composition of the photosensitive resin composition of Example 1.

Examples 2 to 13 and Comparative Examples 1 to 6
A photosensitive resin composition was prepared in the same manner as in Example 1 except that the composition of the photosensitive resin composition was changed to that shown in Table 2, and a printing original plate was obtained. The obtained printing plate was evaluated in the same manner as in Example 1. These evaluation results are shown in Table 2 together with the compositions of the photosensitive resin compositions of Examples 2 to 13 and Comparative Examples 1 to 6.

The details of (iii) photopolymerizable unsaturated compounds (iii-1 to iii-5), (iv) photopolymerization initiators, plasticizers, and thermal polymerization inhibitors described in Table 2 are as follows. is there.
iii-1: 4-acryloylmorpholine manufactured by KJ Chemicals Co., Ltd. iii-2: 2-acryloyloxyethyl-phthalic acid HOA-MPL (N) manufactured by Kyoeisha Chemical Co. iii-3: glycerol dimethacrylate manufactured by Kyoeisha Chemical Co. iii-4 : 2-hydroxy-3-acryloyloxypropyl methacrylate NK ester 701A manufactured by Shin-Nakamura Chemical Co. iii-5: propylene glycol diepoxy acrylate epoxy ester 70PA manufactured by Kyoeisha Chemical Co., Ltd. Photopolymerization initiator: benzyl dimethyl ketal Plasticizer: diethylene glycol thermal polymerization Inhibitor: Hydroquinone monomethyl ether

  As can be seen from Table 2, in Examples 1 to 13, as the tertiary nitrogen atom-containing polyamide, structural units and alicyclic structural units obtained from cyclohexanedicarboxylic acid are within the scope of the present invention (each 20 to 50 mol%, Since the tertiary nitrogen atom-containing polyamide contained in the range of 50 to 95 mol% is used, it is excellent in all of brush chip resistance, adhesiveness of the printing plate surface, image reproducibility, and printing durability. On the other hand, as shown in Comparative Example 1, if the tertiary nitrogen atom-containing polyamide is not included, the brush chip resistance, image reproducibility, and printing durability are poor. As shown in Comparative Examples 2 and 3, when a tertiary nitrogen atom-containing polyamide that does not contain a structural unit obtained from cyclohexanedicarboxylic acid is used, the adhesiveness of the printing plate surface is inferior, and the degree thereof is increased in content. It increases with. In addition, the brush chip resistance and image reproducibility are poor. As shown in Comparative Example 4, even when the structural unit obtained from cyclohexanedicarboxylic acid is contained, if the content is too small, the brush chip resistance and the adhesiveness of the printing plate surface are poor. As shown in Comparative Example 5, even if the structural unit obtained from cyclohexanedicarboxylic acid is contained, if the content is too large, the printing durability is inferior. As shown in Comparative Example 6, even when the structural unit obtained from cyclohexanedicarboxylic acid is contained in an amount within the range of the present invention, if the total content of the alicyclic structural unit is too large, the printing durability is inferior. .

  According to the photosensitive resin composition for a relief printing original plate of the present invention, high highlight halftone dot image reproducibility and printing durability can be maintained, and the tertiary nitrogen atom-containing polyamide content can be increased. It is possible to obtain a relief printing original plate in which the tackiness of the printing plate surface does not increase. Therefore, the present invention is extremely useful.

Claims (6)

  (I) a modified partially saponified polyvinyl acetate having a functional group introduced in the side chain, (ii) a tertiary nitrogen atom-containing polyamide, (iii) a photopolymerizable unsaturated compound, and (iv) a photopolymerization initiator A photosensitive resin composition for a relief printing original plate, wherein (ii) the tertiary nitrogen atom-containing polyamide is an aminocarboxylic acid unit (including lactam as a raw material) in a polyamide molecule, a dicarboxylic acid unit, and a diamine For letterpress printing original plate, comprising 20 to 50 mol% of structural units obtained from cyclohexanedicarboxylic acid and 50 to 95 mol% of alicyclic structural units in total with respect to the total of units Photosensitive resin composition.   (I) Modified partially saponified polyvinyl acetate having a functional group introduced in its side chain, (ii) tertiary nitrogen atom-containing polyamide, (iii) photopolymerizable unsaturated compound in the photosensitive resin composition for letterpress printing original plate And (iv) the amount of the photopolymerization initiator used is 30 to 65% by mass, 5 to 30% by mass, 5 to 25% by mass, and 0.1 to 5% by mass, respectively. 2. The photosensitive resin composition for letterpress printing original plate as described in 1.   3. The photosensitive resin composition for letterpress printing original plate according to claim 1, wherein the (ii) tertiary nitrogen atom-containing polyamide is a polyamide containing a piperazine ring in the molecule.   (I) The modified partially saponified polyvinyl acetate having a functional group in the side chain contains an ester bond and a functional group in the side chain, and the functional group is a photopolymerizable unsaturated group and / or a carboxyl group. The photosensitive resin composition for letterpress printing original plate as described in any one of Claims 1-3 characterized by the above-mentioned.   The letterpress printing original plate according to any one of claims 1 to 4, wherein the (iii) photopolymerizable unsaturated compound contains a heterocyclic-containing photopolymerizable unsaturated compound having a 5- to 7-membered ring. Photosensitive resin composition.   A letterpress printing original plate comprising a photosensitive resin layer formed using the photosensitive resin composition for a letterpress printing original plate according to any one of claims 1 to 5 on a support.