Ink composition, inkjet recording method, producing method of planographic printing plate, and planographic printing plate

1. An ink composition comprising:

(A) a polymerization initiator;

(B) an ester or amide of a mono-functional acrylic acid having an alkylene oxide repeating unit in a molecule; and

(C) a colorant,

wherein (B) the ester or amide of a mono-functional acrylic acid having an alkylene oxide repeating unit in a molecule is a compound expressed by the following formula (I):

wherein, in formula (I), R 1 denotes a hydrogen atom; X denotes an oxygen atom or NR′ in which R′ denotes a hydrogen atom or an alkyl group; Z 1 denotes an ethylene group and Z 2 denotes an alkylene group having 1 to 6 carbon atoms; n is an integer from 3 to 10; m is an integer from 0 to 80; when m is an integer of 1 or more, Z 1 and Z 2 are not the same; and R 2 denotes a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or an aryl group having 6 to 10 carbon atoms;

wherein a content of (B) the ester or amide of a mono-functional acrylic acid having an alkylene oxide repeating unit in a molecule is in the range of 1 to 18 mass percent with respect to a total mass of the ink composition.

2. The ink composition of claim 1 , wherein the ink composition is used for inkjet recording.

3. An inkjet recording method comprising:

(a) discharging the ink composition of claim 1 onto a recording medium; and

(b) irradiating active radiation on the discharged ink composition to cure the ink composition.

4. A method of producing a planographic printing plate, comprising:

(a′) discharging the ink composition of claim 1 onto a hydrophilic support; and

(b′) irradiating active radiation on the discharged ink composition to cure the ink composition to form a hydrophobic image formed by curing the ink composition on the hydrophilic support.

5. An ink composition comprising:

(A) a polymerization initiator;

(B) an ester or amide of a mono-functional acrylic acid having an alkylene oxide repeating unit in a molecule;

(B-2) an ester or amide of a mono-functional (meth)acrylic acid having an alkyl portion having 6 to 12 carbon atoms; and

(C) a colorant;

wherein (B) the ester or amide of a mono-functional acrylic acid having an alkylene oxide repeating unit in a molecule is a compound expressed by the following formula (I):

wherein, in formula (I), R 1 denotes a hydrogen atom; X denotes an oxygen atom or NR′ in which R′ denotes a hydrogen atom or an alkyl group; Z 1 denotes an ethylene group and Z 2 denotes an alkylene group having 1 to 6 carbon atoms; n is an integer from 3 to 10; m is an integer from 0 to 80; when m is an integer of 1 or more, Z 1 and Z 2 are not the same; and R 2 denotes a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or an aryl group having 6 to 10 carbon atoms wherein a content of the (B-2) ester or amide of a mono-functional (meth)acrylic acid having an alkyl portion having 6 to 12 carbon atoms is in the range of 10 to 35 mass percent with respect to a total mass of the ink composition.

6. The ink composition of claim 5 , wherein the ink composition is used for inkjet recording.

7. An inkjet recording method comprising:

(a) discharging the ink composition of claim 5 onto a recording medium; and

(b) irradiating active radiation on the discharged ink composition to cure the ink composition.

8. A method of producing a planographic printing plate, comprising:

(a′) discharging the ink composition of claim 5 onto a hydrophilic support; and

(b′) irradiating active radiation on the discharged ink composition to cure the ink composition to form a hydrophobic image formed by curing the ink composition on the hydrophilic support.

9. An ink composition comprising:

(A) a polymerization initiator;

(B) an ester or amide of a mono-functional acrylic acid having an alkylene oxide repeating unit in a molecule;

(B-3) polyfunctional (meth)acrylate having a weight average molecular weight of less than 360; and

(C) a colorant;

wherein (B) the ester or amide of a mono-functional acrylic acid having an alkylene oxide repeating unit in a molecule is a compound expressed by the following formula (I):

wherein, in formula (I), R 1 denotes a hydrogen atom; X denotes an oxygen atom or NR′ in which R′ denotes a hydrogen atom or an alkyl group; Z 1 denotes an ethylene group and Z 2 denotes an alkylene group having 1 to 6 carbon atoms; n is an integer from 3 to 10; m is an integer from 0 to 80; when m is an integer of 1 or more, Z 1 and Z 2 are not the same; and R 2 denotes a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

10. The ink composition of claim 9 , wherein the ink composition is used for inkjet recording.

11. The ink composition of claim 9 , wherein the (B-3) polyfunctional (meth)acrylate having a weight average molecular weight of less than 360 is a compound expressed by the following formula (II):

wherein in formula (II), R 11 and R 12 each independently denote a hydrogen atom or a methyl group, and X denotes a divalent organic group.

12. The ink composition of claim 9 , wherein a content of the (B-3) polyfunctional (meth)acrylate having a weight average molecular weight of less than 360 is in the range of 10 to 65 mass percent with respect to a total mass of the ink composition.

13. An inkjet recording method comprising:

(a) discharging the ink composition of claim 9 onto a recording medium; and

(b) irradiating active radiation on the discharged ink composition to cure the ink composition.

14. A method of producing a planographic printing plate, comprising:

(a′) discharging the ink composition of claim 9 onto a hydrophilic support; and

(b′) irradiating active radiation on the discharged ink composition to cure the ink composition to form a hydrophobic image formed by curing the ink composition on the hydrophilic support.