Photosensitive resin composition for relief printing original plate and relief printing original plate obtained therefrom
The present invention provides a photosensitive resin composition for a relief printing original plate which can achieve both of a printing reproducibility of gradation of a highlight part and a printing durability, and can further achieve a low plate surface tackiness. A photosensitive resin composition for a relief printing original plate containing water-soluble or water-dispersible polyamide, a photopolymerizable unsaturated compound and a photopolymerization initiator as essential ingredients, characterized in that a total of a content of an alicyclic structural unit obtained from diamine and a content of an alicyclic structural unit obtained from dicarboxylic acid in the polyamide is 30 to 90 molar %, and the content of the alicyclic structural unit obtained from dicarboxylic acid in the polyamide is 20 molar % or more.
1. A water-developable relief printing original plate comprising:
a photosensitive resin layer comprising a photosensitive resin composition for a relief printing original plate, the photosensitive resin composition comprising
water-soluble or water-dispersible polyamide,
a photopolymerizable unsaturated compound, and
a photopolymerization initiator,
wherein a total of a content of an alicyclic structural unit obtained from diamine and a content of an alicyclic structural unit obtained from dicarboxylic acid in the polyamide is 30 to 90 molar %, and
wherein, among the two types of the alicyclic structural units, the content of the alicyclic structural unit obtained from alicylic dicarboxylic acid in the polyamide is 20 molar % or more.
2. The water-developable relief printing original plate according to claim 1 , wherein a storage elastic modulus of the polyamide measured by a dynamic viscoelasticity measuring apparatus is 1000 to 3500 Mpa.
3. The water-developable relief printing original plate according to claim 1 , wherein alicyclic diamine becoming the alicyclic structure unit is at least one alicyclic diamine selected from a group consisting of isophoronediamine, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, norbornyldiamine, 1,4-bis-(3-aminopropyl)piperazine and N-(2-aminoethyl)-piperazine.
4. The water-developable relief printing original plate according to claim 1 , wherein alicyclic dicarboxylic acid is at least one alicyclic dicarboxylic acid selected from the group consisting of isophoronedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,3-norbornane-dicarboxylic acid and 1,3-cyclohexanedicarboxylic acid.
5. The water-developable relief printing original plate according to claim 1 , wherein the polyamide has a tertiary nitrogen atom.
6. The water-developable relief printing original plate according to claim 1 , wherein the polyamide contains 10 to 70 molar % of a structural unit obtained from lactam and/or aminocarboxylic acid.