JP7125675B2 - Photosensitive resin composition for letterpress printing original plate and letterpress printing original plate using the same - Google Patents

Description

TECHNICAL FIELD 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. In particular, the present invention can obtain an original printing plate of analog letterpress printing (analogue plate) that has improved printing quality while maintaining printing durability and reducing the increase in surface tackiness of the printing plate. A photosensitive resin composition that can improve brush chipping resistance when resin residue is removed and printing durability during printing in a letterpress printing original plate (laser engraving plate) for a laser engraving method, and can obtain a printing original plate with improved printing quality. It is about things.

The photosensitive resin composition used for the letterpress printing original plate generally contains a soluble polymer compound, a photopolymerizable unsaturated compound, and a photopolymerization initiator as essential components, and if necessary, a stabilizer, a plasticizer, Additives such as agents are blended. A letterpress printing original plate generally has a structure in which a photosensitive resin layer formed using such a photosensitive resin composition is provided on a support. Currently, there are three types of letterpress printing original plates due to differences in plate making methods: analog letterpress printing original plates (analog plates), CTP method letterpress printing original plates (CTP plates), and laser engraving method letterpress printing original plates (laser engraving plates). types are commonly known.

An analog plate is a type that has been widely known for a long time. Actinic rays are irradiated through a negative film (or positive film) having a transparent image area on a photosensitive resin composition layer, and the photosensitive layer in the exposed area is cured. After that, a relief plate for printing is prepared by a plate-making process in which the photosensitive layer in the non-exposed areas is dissolved and removed with a suitable solvent, dried and post-exposed. Analog versions often require original film using silver halide materials, thus requiring the production time and cost of negative film (or positive film).

CTP (Computer to Plate) plate was developed with the progress of computer technology, and is a negative film (or positive film) creation process in which information processed on a computer is directly output onto the original printing plate. to obtain a printing plate precursor without the need for

On the other hand, the laser engraving plate was developed as a further improvement of the CTP plate, and forms unevenness as a relief by engraving a photosensitive resin layer cured with ultraviolet light with a laser beam. A laser engraving plate has the advantage that the cross-sectional shape of the relief can be freely controlled, unlike an analog plate in which a relief image is produced using a negative film (or positive film), and is spreading.

Development of the letterpress printing original plate is generally carried out using water as a solvent. In order to enable such water development, a water-soluble or water-swellable polymer compound is used as the soluble polymer compound of the photosensitive resin layer in any original plate.

Partially saponified polyvinyl acetate has been used as a soluble polymer compound for the photosensitive resin layer of the letterpress printing original plate in analog plates because of its excellent water developability. However, the original printing plate using the partially aged polyvinyl acetate has a problem of image reproducibility such as lack of halftone dots of highlights when a hard brush is used during water development. In addition, there is a problem of printing durability in that cracks easily occur in the relief during long-run printing due to fragility against printing pressure applied during printing, requiring replacement of the printing plate.

In order to solve these problems, an analog version has been proposed in which a polyvinyl acetate derivative and a tertiary nitrogen atom-containing polyamide are used in combination as a soluble polymer compound (see Patent Documents 1 and 2). This method improves the crack resistance, but has a new problem that the tackiness of the polyamide itself increases the tackiness of the printing plate surface.

In addition, in the analog version, modified partially saponified polyvinyl acetate and a tertiary nitrogen atom-containing polyamide are used as the soluble polymer compound, and a specific 5- to 7-membered ring is used as the photopolymerizable unsaturated compound. A product using a material has been proposed (see Patent Document 3). Although this method was able to further improve the printing durability, the surface tackiness of the printing plate derived from the tertiary nitrogen atom-containing polyamide remained unresolved.

Laser engraving plates using partially saponified polyvinyl acetate as a soluble polymer compound in a photosensitive resin layer are also known (see Patent Documents 4 to 6).

However, even with laser engraving plates, photosensitive resin compositions using partially saponified polyvinyl acetate and its derivatives have poor printing durability against repeated impacts during printing, and cracks occur in the relief during printing. problem was occurring.

As a method for solving the problem of printing durability in laser engraving plates, Patent Document 7 proposes to improve printing durability by blending modified partially saponified polyvinyl acetate with a basic nitrogen-containing polyamide. there is Further, in Patent Document 8, printing durability is further improved by adding a photopolymerizable unsaturated compound having a specific heterocyclic ring to a photosensitive resin composition in which a polyvinyl acetate derivative and a basic nitrogen-containing polyamide are blended. is proposed.

On the other hand, the production of a laser engraving plate requires a washing step to remove resin scum generated during laser engraving from the surface of the printing plate because it adheres to the surface of the printing plate. However, in conventional printing original plates based on photosensitive resin compositions using partially saponified polyvinyl acetate and its derivatives, fine lines and isolated dots formed on the surface of the printing plate are chipped when washed with a brush. There was a problem that image reproducibility deteriorated. Therefore, there is a restriction that a spray method must be adopted as a cleaning method, and a special device is required. Therefore, it is demanded to provide a laser engraving plate which is excellent in printing durability during printing and in which image reproducibility is less deteriorated even when a brush is used in a cleaning step for removing resin residue adhering to the surface of the printing plate after laser engraving. It had been.

JP-A-11-65115 Japanese Patent Application Laid-Open No. 2001-272776 WO2014/021322 JP-A-11-170718 Japanese Patent Application Laid-Open No. 2001-328365 JP 2010-58491 A Japanese Unexamined Patent Application Publication No. 2006-2061 WO2014/129243

The present invention was invented in view of the current state of the conventional letterpress printing original plate described above, and an object of the present invention is to provide a photosensitive resin composition for a letterpress printing original plate that solves the above-described problems of the prior art, and a composition using the same. To provide a letterpress printing original plate. In particular, it is an object of the present invention to provide analog plates with excellent image reproducibility without lack of highlight halftone dots even when developed with a hard brush while maintaining printing durability, and furthermore, having a third-class printing plate. An object of the present invention is to provide a photosensitive resin composition for an original plate which does not increase surface tackiness even when the blending ratio of a nitrogen atom-containing polyamide is increased. The object of the present invention is to provide a photosensitive resin composition for an original plate, which has the above properties and is less likely to deteriorate in image reproducibility even when a cleaning step after laser engraving is performed with a brush.

As a result of intensive studies to achieve the above object, the present inventors found that, among the photosensitive resin compositions used for letterpress printing original plates, aminocarboxylic acid units ( A tertiary nitrogen atom containing specific amounts of structural units obtained from cyclohexanedicarboxylic acid and alicyclic structural units with respect to the sum of dicarboxylic acid units and diamine units (including the case of lactam as a raw material) By using a polyamide containing tertiary nitrogen atoms, analog printing plates have high reproducibility of halftone dot images of highlights without chipping during development while maintaining printing durability. It is possible to provide a plate that does not increase the tackiness of the surface of the printing plate even if the rate is increased, and in the laser engraving plate, while having excellent printing durability during printing, the cleaning process after laser engraving The present inventors have found that even if the above is performed with a brush, the image reproducibility is less deteriorated, and the present invention has been completed.

The present invention has been completed based on the above findings, and has the following configurations (1) to (8).
(1) (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 initiation (ii) a tertiary nitrogen atom-containing polyamide containing an aminocarboxylic acid unit (including a lactam as a raw material) and a dicarboxylic acid unit in the polyamide molecule; , and containing 20 to 50 mol% of structural units obtained from cyclohexanedicarboxylic acid, and a total of 50 to 95 mol% of alicyclic structural units, based on the total of diamine units. A photosensitive resin composition for printing original plates.
(2) In the photosensitive resin composition for letterpress printing original plate, (i) modified partially saponified polyvinyl acetate having a functional group introduced into the side chain, (ii) tertiary nitrogen atom-containing polyamide, (iii) photopolymerization The amount of the unsaturated compound and (iv) the photopolymerization initiator used is 30 to 65% by mass, 5 to 30% by mass, 5 to 35% by mass, and 0.1 to 5% by mass, respectively. The photosensitive resin composition for a letterpress printing original plate according to (1).
(3) The photosensitive resin composition for a letterpress printing original plate according to (1) or (2), wherein the (ii) tertiary nitrogen atom-containing polyamide is a polyamide containing a piperazine ring in the molecule. thing.
(4) The (i) 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 or a carboxyl group.
(5) Any one of (1) to (4), wherein the photopolymerizable unsaturated compound (iii) contains a heterocyclic ring-containing photopolymerizable unsaturated compound having a 5- to 7-membered ring. The photosensitive resin composition for a letterpress printing original plate described above.
(6) A letterpress printing original plate characterized by having 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.
(7) The original letterpress printing plate according to (6), wherein the original letterpress printing plate is an analog type letterpress printing original plate.
(8) The original relief printing plate as described in (6), which is a laser engraving original letterpress printing plate.

According to the photosensitive resin composition for letterpress printing original plate of the present invention, in the analog plate, high highlight halftone dot image reproducibility and printing durability are maintained, and the blending ratio of the tertiary nitrogen atom-containing polyamide It is possible to prevent the tackiness of the printing plate surface from increasing even if it is increased, and in the laser engraving plate, while having excellent printing durability during printing, the cleaning process after laser engraving can be brushed. Even if it is carried out at , the deterioration of image reproducibility can be reduced.

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

(Photosensitive resin composition for letterpress printing original plate)
The photosensitive resin composition for a letterpress printing original plate of the present invention comprises (i) a modified partially saponified polyvinyl acetate having a functional group introduced into the side chain, (ii) a tertiary nitrogen atom-containing polyamide, and (iii) photopolymerizable (iv) a photopolymerization initiator, and (ii) a tertiary nitrogen atom-containing polyamide containing a specific structural unit in a specific ratio, thereby producing an analog In printing plates, it effectively prevents the increase in tackiness of the printing plate surface, which is a drawback of conventional tertiary nitrogen atom-containing polyamides, while maintaining a high level of highlight dot image reproducibility and printing durability. In the laser engraving plate, a laser engraving plate that has excellent printing durability during printing and that can reduce deterioration in image reproducibility even when the washing process after laser engraving is performed with a brush. It is characterized by being able to obtain

(i) Modified partially saponified polyvinyl acetate in which a functional group is introduced into the side chain (hereinafter also referred to as component (i)) is 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, preferably a (meth)acryloyl group. 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. Moreover, by introducing a carboxyl group, the compatibility with the tertiary nitrogen atom-containing polyamide can be improved by quaternary salting. Furthermore, since the functional group has an ester bond, (iii) the compatibility with the photopolymerizable unsaturated compound is improved, and the photocrosslinking reaction can be performed efficiently. In particular, introduction of both a photopolymerizable unsaturated group and a carboxyl group can reduce relief chipping during development and improve compatibility with the tertiary nitrogen atom-containing polyamide.

Methods for introducing carboxyl groups into the side chains of modified partially saponified polyvinyl acetate include a method of reacting a hydroxyl group in the partially saponified polyvinyl acetate with an acid anhydride to introduce a carboxyl group into the side chains of the polymer, A method of partially saponifying a polymer obtained by copolymerizing vinyl acetate and an unsaturated carboxylic acid or a salt thereof or an unsaturated carboxylic acid ester to introduce a carboxyl group into a side chain can be mentioned. The side chains of the modified partially saponified polyvinyl acetate obtained by these methods also contain an ester bond, which is more preferable from the viewpoint of (iii) compatibility with the photopolymerizable unsaturated compound. In addition, the modified partially saponified polyvinyl acetate obtained by this method is preferable because the introduction of reactive groups is easy and the effects of the present invention are remarkably exhibited.

As a method for introducing a photopolymerizable unsaturated group into the side chain of the modified partially saponified polyvinyl acetate, a modified partially saponified polyvinyl acetate having a carboxyl group introduced into the side chain is used to obtain a modified partially saponified polyvinyl acetate. A method of introducing a reactive group by reacting a carboxyl group in the resin with a photopolymerizable unsaturated group-containing epoxy compound can be exemplified. The side chains of the modified partially saponified polyvinyl acetate obtained by this method also contain an ester bond, which is more preferable from the viewpoint of (iii) compatibility with the photopolymerizable unsaturated compound. In addition, the modified partially saponified polyvinyl acetate obtained by this method is preferable because the introduction of reactive groups is easy and the effects of the present invention are remarkably exhibited.

Another method for introducing a photopolymerizable unsaturated group into modified partially saponified polyvinyl acetate is to react partially saponified polyvinyl acetate with an acrylic compound having an N-methylol group to produce partially saponified polyvinyl acetate. A method of introducing a reactive group into a side chain can be mentioned. As a specific manufacturing condition, when 5 to 30 parts by mass of an acrylic compound is reacted 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. and is preferable. N-methylol acrylamide and N-methylol methacrylamide are particularly preferable as acrylic compounds having an N-methylol group. Each of these may be used alone, or two or more thereof may be used in combination.

The amount of functional groups to be introduced into the side chains of the modified partially saponified polyvinyl acetate is preferably 0.1 to 0.7 mol/kg in the modified partially saponified polyvinyl acetate. If it is more than 0.7 mol/kg, the water solubility may deteriorate, and if it is less than 0.1 mol/kg, it may be difficult to obtain the improvement effect.

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 degree of saponification is less than the above range, the water developability may be lowered due to a decrease in hydrophilicity. There is a risk of

The average degree of polymerization of the modified partially saponified polyvinyl acetate is preferably in the range of 200-1500, more preferably in the range of 500-1000. If the average degree of polymerization is less than the above range, the water resistance may deteriorate, and if the average degree of polymerization exceeds the above range, the water developability may deteriorate.

The amount of component (i) used in the photosensitive resin composition of the present invention is preferably 30 to 65% by mass, more preferably 35 to 65% by mass, still more preferably 40 to 60% by mass. If the amount of component (i) used is less than the above range, the shape retention of the photosensitive resin layer may be low and handleability may be poor.

(ii) tertiary nitrogen atom-containing polyamide (hereinafter also referred to as component (ii)) contains aminocarboxylic acid units (including the case of lactam as a raw material), dicarboxylic acid units, and diamine units in the polyamide molecule. On the other hand, it contains 20 to 50 mol % of structural units obtained from cyclohexanedicarboxylic acid and 50 to 95 mol % of alicyclic structural units in total. The alicyclic structural units herein naturally include structural units obtained from cyclohexanedicarboxylic acid.

Component (ii) used in the present invention contains specific amounts of structural units obtained from cyclohexanedicarboxylic acid and alicyclic structural units as described above. It is possible to improve the problem of chipping of highlight halftone dots during development and chipping of relief during printing. There is an effect that there is little increase in the tackiness of the adhesive. Therefore, according to the present invention, in the analog version, it is possible to increase the amount added, which was impossible due to the hygroscopicity and high adhesiveness of conventional tertiary nitrogen atom-containing polyamides, and (ii) ) can enhance the effect of the formulation of the component. Further, in laser engraving plates, it has the effect of being excellent in resistance to brush chipping when removing resin scum while being excellent in printing durability during printing.

Component (ii) is not only alicyclic dicarboxylic acids, including cyclohexanedicarboxylic acid, alicyclic diamines, and tertiary nitrogen atom-containing diamines, but also monomers such as diamines, dicarboxylic acids, ω-amino acids, lactams, etc. It can be obtained by polymerizing a compound as a raw material.

As described above, cyclohexanedicarboxylic acid has a structure obtained from cyclohexanedicarboxylic acid with respect to the sum of aminocarboxylic acid units (including the case of lactam as a raw material), dicarboxylic acid units, and diamine units in the polyamide molecule It is used in an amount such that the unit is 20 to 50 mol %. In the analog plate, if the proportion of the structural unit derived from cyclohexanedicarboxylic acid is less than the above range, the surface tackiness of the printing plate increases, and if it exceeds the above range, the effect of improving printing durability is small. In laser engraving plates, if the ratio of the structural unit derived from cyclohexanedicarboxylic acid is less than the above range, brush chipping resistance is poor, and if it exceeds the above range, the effect of improving brush chipping resistance 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-3-ethyl-1,4-cyclohexanedicarboxylic acid, 2-methyl-3-propyl-1,4-cyclohexanedicarboxylic acid, 2-methyl- 3-butyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-3-propyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-3-butyl-1,4-cyclohexanedicarboxylic acid, 2-methyl-3- and t-butyl-1,4-cyclohexanedicarboxylic acid. Among these, 1,4-cyclohexanedicarboxylic acid is preferable from the viewpoint of gradation printability reproducibility in highlight areas.

As described above, component (ii) contains a total of 50 alicyclic structural units with respect to the total of aminocarboxylic acid units (including the case of lactam as a raw material), dicarboxylic acid units, and diamine units in the polyamide molecule. Contains up to 95 mol %. The alicyclic structural units include, in addition to cyclohexanedicarboxylic acid, structural units obtained from alicyclic dicarboxylic acids and, if necessary, alicyclic diamines and alicyclic aminocarboxylic acids added thereto. In the analog version, if the total content of the alicyclic structural units is less than the above range, the compatibility with component (i) is poor, so the amount of component (ii) cannot be increased. When the range is exceeded, the printing durability is deteriorated. In the laser engraving plate, if the total content of the alicyclic structural units is less than the above range, the brush chipping resistance is poor, and if it exceeds the above range, the printing durability is poor. In the present invention, the term "alicyclic diamine" includes not only diamines of saturated and unsaturated cyclic hydrocarbons but also diamines having a heterocyclic ring such as piperazines.

Examples of alicyclic dicarboxylic acids other than cyclohexanedicarboxylic acid described above include isophoronedicarboxylic acid, 2,3-norbornanedicarboxylic acid, 2,6-decalinedicarboxylic acid, 3-methyl-2,6-decalinedicarboxylic acid, 3- ethyl-2,6-decalindicarboxylic acid, 3-propyl-2,6-decalindicarboxylic acid, 3-butyl-2,6-decalindicarboxylic acid, 3,4-dimethyl-2,6-decalindicarboxylic acid, 3, 4-diethyl-2,6-decalindicarboxylic acid, 3,4-dipropyl-2,6-decalindicarboxylic acid, 3,4-dibutyl-2,6-decalindicarboxylic acid, 3,8-dimethyl-2,6- decalindicarboxylic acid, 3,8-diethyl-2,6-decalindicarboxylic acid, 3,8-dipropyl-2,6-decalindicarboxylic acid, 3,8-dibutyl-2,6-decalindicarboxylic acid, 3-methyl- 4-ethyl-2,6-decalindicarboxylic acid, 3-methyl-4-propyl-2,6-decalindicarboxylic acid, 3-methyl-4-butyl-2,6-decalindicarboxylic acid, 3-ethyl-4- Butyl-2,6-decalinedicarboxylic acid may be mentioned.

Examples of the above-mentioned alicyclic diamine include isophoronediamine, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, 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, tricyclodecanediamine. Among these, isophoronediamine and 1,3-bis(aminomethyl)cyclohexane are preferred from the viewpoint of compatibility with component (i).

Examples of the above-mentioned alicyclic aminocarboxylic acids include 4-aminocyclohexanecarboxylic acid, 3-aminocyclohexanecarboxylic acid, 4-(aminomethyl)cyclohexanecarboxylic acid, 3-(aminomethyl)cyclohexanecarboxylic acid, 2-amino Methylcyclopropanecarboxylic acid may be mentioned.

Component (ii) used in the present invention is a polyamide containing a tertiary nitrogen atom in the molecule, specifically in a portion 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, etc. The tertiary nitrogen atom is preferably a piperazine ring or an N,N-dialkylamino group, more preferably a piperazine ring. Examples of monomers having a tertiary nitrogen atom for producing component (ii) include aliphatic diamines having a tertiary nitrogen atom, such as diamines having a piperazine ring and methyliminobispropylamine. Diamines having a piperazine ring include N,N'-bis(aminoethyl)-piperazine, N,N'-bis(3-aminopropyl)piperazine and N,N'-di(aminopentyl)piperazine. Among these, N,N'-bis(3-aminopropyl)piperazine is preferred. ω-amino acids such as N,N'-dimethyl-N-(aminomethyl)-N'-(carboxymethyl)-ethylenediamine can also be used.

The amount of component (ii) used in the photosensitive resin composition of the present invention is preferably 5 to 30% by mass, more preferably 8 to 25% by mass. In analog plates, if the amount of component (ii) used is less than the above range, brush chipping resistance, image reproducibility, and printing durability may be deteriorated. A decrease in the blending amount may impair the shape retention of the original plate. In particular, in the present invention, in the analog plate, even if the amount of component (ii) used is increased to 8% by mass or more in the photosensitive resin composition, the problem of increased tackiness on the surface of the printing plate is conspicuous. do not have. Therefore, the effect of adding component (ii) to the photosensitive resin composition for letterpress printing original plates can be further enhanced by increasing the amount used. If the amount of component (ii) used in the laser engraving plate is less than the above range, brush chipping resistance and printing durability may be deteriorated. A decrease in the amount may impair the shape retention of the original plate.

(iii) As the photopolymerizable unsaturated compound (hereinafter also referred to as (iii) component), those conventionally used in this technical field by those skilled in the art can be used, for example, having a 5- to 7-membered ring It preferably contains a heterocyclic ring-containing photopolymerizable unsaturated compound. A heterocyclic ring-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 form hydrogen bonds with the hydroxyl groups in component (i), compatibility with component (i) can be enhanced. The heterocyclic ring-containing photopolymerizable unsaturated compound having a 5- to 7-membered ring preferably has a molecular weight of 300 or less. If the molecular weight is too large, the compatibility with component (i) may decrease.

Component (iii) includes, for example, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, phenoxymethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 2-(meth)acryloyl oxyethylhexahydrophthalate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl phthalate, neopentyl glycol-(meth)acrylic acid-benzoate, (meth)acryloyl Morpholine, styrene and its derivatives, vinylpyridine, N-vinyl-2-pyrrolidone, β-(meth)acryloyloxyethyl hydrogen phthalate, N-phenylmaleimide and its derivatives, N-(meth)acryloxysuccinimide, ( 2-naphthyl meth)acrylate, N-phenyl(meth)acrylamide, and the like can be used. Among them, (meth)acryloylmorpholine is preferred.

The amount of component (iii) used in the photosensitive resin composition of the present invention is preferably 5 to 35% by mass, more preferably 15 to 35% by mass. If the amount of component (i) used is less than the above range, image reproducibility may be insufficient, and if it exceeds the above range, the photosensitive resin layer used in the letterpress printing original plate may become difficult to solidify.

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

The photosensitive resin composition of the present invention may further contain optional components such as a plasticizer and a polymerization inhibitor. Plasticizers are used to increase flexibility, and specific examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, glycerin and derivatives thereof, trimethylolpropane and derivatives thereof, trimethylolethane and derivatives thereof, and pentaerythritol. and polyhydric alcohols such as derivatives thereof. The amount of these plasticizers used is preferably 20% by mass or less of the total mass of the photosensitive resin composition of the present invention. The polymerization inhibitor is for increasing the thermal stability, and specific examples thereof include phenols, hydroquinones, catechols, hydroxylamine derivatives and the like. The amount of these polymerization inhibitors used is preferably 0.001 to 5% by mass of the total mass of the photosensitive resin composition of the present invention.

Furthermore, optional ingredients such as dyes, pigments, surfactants, antifoaming agents, ultraviolet absorbers, fragrances, etc. can be blended at a maximum ratio of 10% by mass of the photosensitive resin composition, if necessary.

(Toppan printing original plate)
The letterpress printing original plate of the present invention is prepared by appropriately mixing the above-described essential components (i) to (iv) and optional components to prepare a photosensitive resin composition, which is used in a melt molding method. In addition, for example, it can be obtained by molding into the intended laminate structure by a known method such as hot pressing, casting, melt extrusion, or solution casting.

The letterpress printing original plate can be used by laminating a sheet-shaped molding (a photosensitive resin layer or an unexposed resin) on a support with or without a known adhesive. As the support, conventionally known materials such as steel, aluminum, glass, and plastic films such as polyester films can be used, and films having a thickness in the range of 50 to 500 μm are generally used. When supplying a sheet-shaped molded product (photosensitive resin layer or unexposed resin) as a laminate laminated on a support, a protective film is placed in contact with the sheet-shaped molded product (photosensitive resin layer or unexposed resin). is preferably further laminated. A film-shaped plastic can be used for the protective film, and for example, a polyester film having a thickness of 125 μm is used. Further, an anti-adhesion layer may be provided between the photosensitive resin layer and the protective film, in which a non-adhesive, transparent polymer that is dispersed or dissolved in a developer is applied to a thickness of 0.5 to 3 μm. By providing an anti-adhesive layer on the surface of the photosensitive resin layer, the protective layer can be easily peeled off during the next exposure operation even if the surface is strongly tacky.

In the letterpress 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-adhesive layer. Since the cap layer is not removed in the developing 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.

Next, a method of making a letterpress printing plate from a letterpress printing original plate to a letterpress printing plate will be described. First, in the case of an analog plate, a negative film having a transparent image area is closely adhered to the photosensitive resin layer and superimposed, and exposure is performed by irradiating actinic rays from above to insolubilize only the exposed areas through which the actinic rays are transmitted. Create a master version. Actinic rays usually use light sources such as high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, and chemical lamps centering on wavelengths of 300 to 450 nm. Then, the unexposed portions are dissolved and removed with a suitable solvent, particularly neutral water in the present invention, but it is preferable to dissolve and remove the unexposed portions 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 portions have been dissolved away is subjected to draining, drying, and post-exposure steps to obtain the final printing plate.

In the case of a laser engraving plate, first, the photosensitive resin layer in the obtained printing original plate is irradiated with ultraviolet rays to be crosslinked and cured. Although the conditions for ultraviolet irradiation are not particularly limited, for example, the surface of the photosensitive resin layer can be exposed for 5 to 15 minutes with an ultraviolet exposure device (light source: Philips 10R) of about 8 mW/cm ² . Next, the original printing plate is mounted on the surface of a plate mounting drum of a laser engraving device, and the irradiated portion of the original plate is decomposed by laser light irradiation according to the image to form recessed portions, and an image is formed to obtain a printing plate. . During this laser beam irradiation (laser engraving), resin residue is generated and adheres to the surface of the printing plate. Therefore, the printing plate is washed to remove these resin residues from the surface of the printing plate. The cleaning of the printing plate does not have to be done with a special device, but can be done with a brush. With conventional laser engraving plates, if cleaning is done with a brush, fine lines and isolated dots formed on the surface of the printing plate will be lost, resulting in poor image reproducibility. was requested. On the other hand, the laser engraving plate of the present invention does not have such problems and can be easily washed using an inexpensive brush.

The present invention will be described in more detail below with reference to (A) Examples of analog plates and (B) Examples of laser engraving plates, but the present invention is not limited to these.

(A) Example of analog version The number of parts in (text) in the examples indicates parts by weight, and the polyamide composition in Table 1 indicates mol %. The mol % of the polyamide composition was determined by H-NMR measurements. The evaluation of characteristic values in the examples was based on the following methods.

(1) 30 μm fine line brush chipping resistance First, a negative including a 30 μm fine line as an image was used on a letterpress printing original plate having a photosensitive resin layer with a thickness of 685 μm, and a chemical lamp whose illuminance was adjusted to 25 W / m ² was used. was exposed for 8 minutes from a distance of 5 cm in height from the surface of the photosensitive resin layer. Then, it was developed with tap water at 25° C. using a brush-type washer (model JW-A2-PD manufactured by Nippon Denshi Seiki Co., Ltd.) using nylon brushes of several different diameters to obtain a relief image. After further drying with hot air at 60° C. for 10 minutes, it was post-exposed for 30 seconds with an ultra-high pressure mercury lamp to obtain a printing plate. The reproducibility of the 30 μm thin line was observed under a microscope at a magnification of 50 times, and evaluated according to the following criteria.
⊚: No chipping of fine lines with a brush diameter of 200 μm.
◯: No chipping in fine lines with a brush diameter of 150 μm.
Δ: No chipping in fine lines with a brush diameter of 120 μm.
x: Even with a brush diameter of 120 μm, fine lines are chipped.

(2) Adhesiveness of printing plate surface First, a printing evaluation negative containing a solid image (width 1 cm × length 5 cm) was used as an image on a letterpress printing original plate having a photosensitive resin layer with a thickness of 685 μm, and the illumination was set to 25 W / m. Using a chemical lamp adjusted to ² , the photosensitive resin layer was exposed from a height of 5 cm from the surface for 8 minutes. Then, it was developed with tap water at 25° C. using a brush-type washer (120 μmφ nylon brush, manufactured by Nippon Denshi Seiki Co., Ltd. JW-A2-PD type) to obtain a relief image. After further drying with hot air at 60° C. for 10 minutes, it was post-exposed for 30 seconds with an ultra-high pressure mercury lamp to obtain a printing plate. Using the obtained printing plate, the surface tackiness of the printing plate was evaluated. The tackiness was evaluated by pressing a coated paper (Gloss PW-8K, manufactured by Lintec Co., Ltd.) as a printed material against the plate and evaluating the degree of slippage of the coated paper according to the following criteria.
A: Even if the coated paper is pressed against the plate 100 times or more, the coated paper slides without resistance.
◯: The coated paper slides without resistance, but some resistance is felt when the coated paper is pressed against the plate 100 times or more.
Δ: When the coated paper is pressed against the plate, the coated paper and the plate immediately adhere to each other. However, when force is applied, the coated paper slips.
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, a letterpress printing original plate having a photosensitive resin layer with a thickness of 685 μm was used, and a negative containing 200 lines and 1% fine lines was used as an image, and a chemical lamp whose illuminance was adjusted to 25 W/m ² was used. was exposed for 8 minutes from a distance of 5 cm in height from the surface of the photosensitive resin layer. Then, it was developed with tap water at 25° C. using a brush-type washer (model JW-A2-PD manufactured by Nippon Denshi Seiki Co., Ltd.) using nylon brushes of several different diameters to obtain a relief image. After further drying with hot air at 60° C. for 10 minutes, it was post-exposed for 30 seconds with an ultra-high pressure mercury lamp to obtain a printing plate. The reproducibility of 200-line 1% halftone dots was observed under a microscope at a magnification of 50 times, and evaluated according to the following criteria.
A: A 200-line 1% halftone dot is perfectly reproduced with a brush diameter of 200 µm.
◯: 200-line 1% halftone dots are perfectly reproduced with a brush diameter of 150 μm.
Δ: A 200-line 1% halftone dot is perfectly reproduced with a brush diameter of 120 μm.
x: 200-line 1% halftone dots are not reproduced even with a brush diameter of 120 µm.

(4) Printing durability A printing plate was manufactured in the same manner as when the relief for evaluating the adhesiveness of the printing plate surface was created in (2) above, and 10,000 shots were made with a pressure of 50 μm from the appropriate printing pressure. After printing 10,000 shots, the printed matter and the plate were observed under a microscope magnified 200 times and evaluated according to the following criteria.
⊚: Observation with a microscope magnified 200 times showed no defects on the printed material and no cracks on the plate.
◯: Observation with a microscope magnified 200 times showed no defects in the printed matter, but slight cracks were found in the plate.
Δ: Defects cannot be visually confirmed on the printed matter or the plate, but defects are observed in the printed matter or the plate when observed with a microscope magnified 200 times.
x: Defects can be visually confirmed on the printed material or the plate.

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

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

Synthesis Example Ai-3:
100 parts of partially saponified polyvinyl acetate "KL-05" manufactured by Nippon Synthetic Chemical Industry Co., Ltd. (degree of polymerization: about 500, degree of saponification: 80 mol%) was dissolved in 100 parts of water, and 15 parts of N-methylolacrylamide was dissolved. was added, and 1 part of phosphoric acid was added as an acid catalyst, stirred at 100°C for 4 hours to adjust, then water was removed, and the modified partially saponified poly having functional groups introduced into the side chains, which is the component (i) Vinyl acetate Ai-3 was obtained.

<(ii) Synthesis of tertiary nitrogen atom-containing polyamide>
Synthesis Example Aii-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% An autoclave was charged with 5 parts of an aqueous hypophosphorous acid solution and 3000 parts of water, and after purging with nitrogen, the autoclave was 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 the reaction was allowed to proceed at normal pressure for 1 hour. The maximum polymerization reaction temperature was 255°C. As a result, a tertiary nitrogen atom-containing polyamide Aii-1, which is component (ii), 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 Aii-1 and the ratio of structural units obtained from cyclohexanedicarboxylic acid and alicyclic structural units in the polyamide.

Synthesis Examples Aii-2 to Aii-8
Synthesis was carried out in the same manner as in Synthesis Example Aii-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, (ii ) component tertiary nitrogen atom-containing polyamides Aii-2 to Aii-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 Aii-2 to Aii-8, and the proportions of structural units obtained from cyclohexanedicarboxylic acid and alicyclic structural units in the polyamides.

Example A1
In a three-necked flask equipped with a stirring spatula and a cooling tube, components (i) and (ii) shown in Table 2 were added, and "Solmix" (registered trademark) H-11 (alcohol mixture, Japan Alcohol After mixing 50 parts of a mixed solvent of 50 parts of water with stirring, the mixture was heated at 90° C. for 2 hours to dissolve 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 a polyester film having a thickness of 250 μm with an adhesive composition containing an ultraviolet absorber in a coating thickness of 20 μm. Using the obtained support, the above photosensitive resin composition was cast on the adhesive layer surface of the support, and a coating 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 laminate having a total thickness of 1080 μm was formed using a laminator so that the film side of the coated polyester film having a thickness of 125 μm was in contact with the photosensitive resin composition.

After the raw plate was stored for 7 days or more, printing plate properties and printing durability were evaluated. These evaluation results are shown in Table 2 together with the composition of the photosensitive resin composition of Example A1.

Examples A2 to A13, Comparative Examples A1 to A6
A photosensitive resin composition was prepared in the same manner as in Example A1 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 A1. These evaluation results are shown in Table 2 together with the compositions of the photosensitive resin compositions of Examples A2 to A13 and Comparative Examples A1 to A6.

The details of (iii) photopolymerizable unsaturated compounds (Aiii-1 to Aiii-5), (iv) photopolymerization initiators, plasticizers, and thermal polymerization inhibitors described in Table 2 are as follows. be.
Aiii-1: 4-acryloylmorpholine manufactured by KJ Chemicals Co., Ltd. Aiii-2: 2-acryloyloxyethyl-phthalic acid HOA-MPL (N) manufactured by Kyoeisha Chemical Co., Ltd. Aiii-3: glycerin dimethacrylate manufactured by Kyoeisha Chemical Co., Ltd. Aiii-4 : 2-Hydroxy-3-acryloyloxypropyl methacrylate NK Ester 701A Shin-Nakamura Chemical Co., Ltd. Aiii-5: Propylene glycol diepoxy acrylate Epoxy Ester 70PA 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 A1 to A13, as the tertiary nitrogen atom-containing polyamide, the structural units obtained from cyclohexanedicarboxylic acid and the alicyclic structural units were within the scope of the present invention (each 20 to 50 mol%, 50 to 95 mol %) of the tertiary nitrogen atom-containing polyamide is used, it is excellent in brush chipping resistance, tackiness on the printing plate surface, image reproducibility, and printing durability. On the other hand, as shown in Comparative Example A1, when the tertiary nitrogen atom-containing polyamide is not contained, brush chipping resistance, image reproducibility, and printing durability are poor. As shown in Comparative Examples A2 and A3, when a tertiary nitrogen atom-containing polyamide that does not contain a structural unit obtained from cyclohexanedicarboxylic acid is used, the tackiness of the printing plate surface is poor, and the degree of tackiness increases as the content ratio increases. increases with In addition, the brush chipping resistance and image reproducibility are also inferior. As shown in Comparative Example A4, even if a structural unit obtained from cyclohexanedicarboxylic acid is contained, if the content is too small, brush chipping resistance and printing plate surface tackiness are poor. As shown in Comparative Example A5, even if a structural unit obtained from cyclohexanedicarboxylic acid is contained, if the content is too large, the printing durability is poor. As shown in Comparative Example A6, even if 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 units is too large, the printing durability is poor. .

(B) Examples of Laser Engraving Plate In the examples, parts in (text) represent parts by mass. Moreover, the polyamide composition in Table 3 represents mol%. The mol % of the polyamide composition was determined by H-NMR measurements. The evaluation of characteristic values in the examples was based on the following methods.

(1) Brush chipping resistance (30 μm wide thin line and 100 μm diameter independent point)
The laser-engraved plate was immersed in rinse water, and the 30 μm-wide fine line and the 100 μm-diameter independent point in the engraved portion were brushed and rubbed 10 times with a 10 cm×5 cm brush. The brush used was made of nylon with a brush diameter of 150 μm and a staggered planting length of 15 mm. Thereafter, the dried printing plate was observed under a microscope at a magnification of 200 times, and brush chipping resistance was evaluated according to the following criteria.
A: No chipping occurred.
◯: Fine chipping occurred in part of the image.
Δ: Part of the image is chipped.
x: Chipping occurs on the entire surface of the image.

(2) Printing durability (cracking of solid)
First, a printing plate was produced by the following procedure.
The original plate was exposed for 10 minutes from a distance of 5 cm above the surface of the photosensitive resin layer with an 8 mW/cm ² UV exposure machine (light source: Philips 10R), crosslinked and cured, and then the protective film was peeled off. Next, FlexPose! equipped with a 300W carbon dioxide laser manufactured by Luescher Flexo as a laser engraving device. Laser engraving (direct engraving) was performed using direct to obtain a printing plate. The specifications of this apparatus were laser wavelength 10.6 μm, beam diameter 30 μm, plate mounting drum diameter 300 mm, and processing speed 1.5 hours/0.5 m ² . The conditions for laser engraving are as follows. Note that (i) to (iii) are conditions unique to the apparatus. Conditions (iv) to (vii) can be arbitrarily set, and the standard conditions of this apparatus were adopted for each condition.
(i) Resolution: 2540dpi
(ii) laser pitch: 10 μm
(iii) Drum rotation speed: 982 cm/sec (iv) Top power: 9%
(v) Bottom power: 100%
(vi) shoulder width: 0.30mm
(vii) Evaluation image: 150 lpi, halftone dots from 0 to 100% in increments of 1% After printing 10,000 shots, the printed matter and the plate were observed under a microscope magnified 200 times, and evaluated according to the following criteria.
⊚: No defects on the printed matter and no cracks on the plate.
◯: The printed material has no defects, but the plate has slight cracks.
Δ: Defects cannot be visually confirmed on the printed matter, but defects are observed by observation with a microscope magnified 200 times.
x: Defects can be visually confirmed on the printed matter.

(3) Printing durability (lack of 1% halftone dots)
The 1% halftone dot of the plate obtained in the evaluation of (2) was magnified 200 times with a microscope and evaluated according to the following criteria.
◯: No change in 1% halftone dots before and after printing.
C: Less than 20% of 1% halftone dots are chipped after printing.
x: Chipping occurs in 20% or more of 1% halftone dots after printing.

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

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

Synthesis Example Bi-3:
100 parts of partially saponified polyvinyl acetate "KL-05" manufactured by Nippon Synthetic Chemical Industry Co., Ltd. (degree of polymerization: about 500, degree of saponification: 80 mol%) was dissolved in 100 parts of water, and 15 parts of N-methylolacrylamide was dissolved. was added, and 1 part of phosphoric acid was added as an acid catalyst, stirred at 100°C for 4 hours to adjust, then water was removed, and the modified partially saponified poly having functional groups introduced into the side chains, which is the component (i) Vinyl acetate Bi-3 was obtained.

<(ii) Synthesis of tertiary nitrogen atom-containing polyamide>
Synthesis Example Bii-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% An autoclave was charged with 5 parts of an aqueous hypophosphorous acid solution and 3000 parts of water, and after purging with nitrogen, the autoclave was 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 the reaction was allowed to proceed at normal pressure for 1 hour. The maximum polymerization reaction temperature was 255°C. Thus, a tertiary nitrogen atom-containing polyamide Bii-1, which is component (ii), 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 3 shows the composition of this tertiary nitrogen atom-containing polyamide Bii-1 and the ratio of structural units obtained from cyclohexanedicarboxylic acid and alicyclic structural units in the polyamide.

Synthesis Examples Bii-2 to Bii-7
Synthesis was carried out in the same manner as in Synthesis Example Bii-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 3 was obtained. ) component, tertiary nitrogen-containing polyamides Bii-2 to Bii-7 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 3 shows the compositions of these tertiary nitrogen atom-containing polyamides Bii-2 to Bii-7, and the proportions of structural units obtained from cyclohexanedicarboxylic acid and alicyclic structural units in the polyamides.

Example B1
In a three-necked flask equipped with a stirring spatula and a cooling tube, components (i) and (ii) shown in Table 4 were added, and "Solmix" (registered trademark) H-11 (alcohol mixture, Japan Alcohol After mixing 50 parts of a mixed solvent of 50 parts of water with stirring, the mixture was heated at 90° C. for 2 hours to dissolve 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 produced. A support having an adhesive layer was obtained by coating a polyester film having a thickness of 250 μm with an adhesive composition containing an ultraviolet absorber in a coating thickness of 20 μm. Using the obtained support, the photosensitive resin composition was cast on the adhesive layer surface of the support, laminated with a polyester film (protective film) having a thickness of 125 μm, and a support having an adhesive layer. A sheet-like laminate master plate having a total thickness of 1080 μm was formed by interposing a photosensitive resin layer having a thickness of 685 μm between a polyester film (protective film) having a thickness of 125 μm.

After the original plate was stored for 7 days or more, the presence or absence of chipping in the image area and printing durability were evaluated. These evaluation results are shown in Table 4 together with the composition of the photosensitive resin composition of Example B1.

Examples B2 to B13, Comparative Examples B1 to B5
A photosensitive resin composition was prepared in the same manner as in Example B1 except that the composition of the photosensitive resin composition was changed to that shown in Table 4, and a printing original plate was obtained. The obtained printing plate was evaluated in the same manner as in Example B1. These evaluation results are shown in Table 4 together with the compositions of the photosensitive resin compositions of Examples B2 to B13 and Comparative Examples B1 to B5.

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

As can be seen from Table 4, in Examples B1 to B13, as the tertiary nitrogen atom-containing polyamide, the structural units obtained from cyclohexanedicarboxylic acid and the alicyclic structural units were within the scope of the present invention (each 20 to 50 mol%, 50 to 95 mol %) of the tertiary nitrogen atom-containing polyamide is used, the brush chipping resistance and printing durability are all excellent. On the other hand, as shown in Comparative Example B1, when the tertiary nitrogen atom-containing polyamide is not included, brush chipping resistance and printing durability are poor. As shown in Comparative Examples B2 and B3, when a tertiary nitrogen atom-containing polyamide that does not contain structural units obtained from cyclohexanedicarboxylic acid is used, brush chipping resistance is poor. As shown in Comparative Example B4, even if a structural unit obtained from cyclohexanedicarboxylic acid is contained, if the content is too small, the brush chipping resistance is also inferior. As shown in Comparative Example B5, even if 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 units is too large, the printing durability is poor. .

According to the photosensitive resin composition for letterpress printing original plates of the present invention, for analog plates, high-level highlight dot image reproducibility and printing durability are maintained, and the blending ratio of the tertiary nitrogen atom-containing polyamide is It is possible to prevent the tackiness of the printing plate surface from increasing even if the viscosity is increased, and for laser engraving plates, the cleaning process after laser engraving is performed with a brush while maintaining excellent printing durability during printing. However, deterioration in image reproducibility can be reduced. Therefore, the present invention is extremely useful.

Claims (1)

A letterpress printing original plate having a photosensitive resin layer on a support, wherein the photosensitive resin layer comprises (i) modified partially saponified polyvinyl acetate having functional groups introduced into side chains, and (ii) tertiary nitrogen. A photosensitive resin composition containing an atom-containing polyamide, (iii) a photopolymerizable unsaturated compound, and (iv) a photopolymerization initiator, wherein (ii) the tertiary nitrogen atom-containing polyamide is Containing 20 to 50 mol% of structural units obtained from cyclohexanedicarboxylic acid with respect to the total of aminocarboxylic acid units (including the case of lactam as a raw material), dicarboxylic acid units, and diamine units, and alicyclic It is formed using a photosensitive resin composition containing a total of 50 to 95 mol% of structural units and further containing 5 mol% or more of structural units obtained from ε-caprolactam , and a letterpress printing original plate , a letterpress printing original plate characterized by being a laser engraving type letterpress printing original plate.