Aspherical-polymer fine particles and production method thereof, and method for producing lithographic printing plate, ink composition and electrophoretic particle composition

1 . Aspherical-polymer fine particles comprising resin particles synthesized by polymerizing radically at least one radical polymerizable monomer in a non-aqueous solvent in the presence of a resin for dispersal stability, wherein the aspherical-polymer fine particles have a sphericity of 0.95 or less.

2 . The aspherical-polymer fine particles as claimed in claim 1 , wherein the at least one radical polymerizable monomer is a compound having at least two polymerizable groups in one molecule thereof.

3 . The aspherical-polymer fine particles as claimed in claim 1 , wherein the at least one radical polymerizable monomer is a monomer having at least two ethylene unsaturated bonds in the molecule thereof the at least two ethylene unsaturated bonds having different reactivities from one another with radical.

4 . The aspherical-polymer fine particles as claimed in claim 1 , wherein the at least one radical polymerizable monomer is a compound represented by the formula (I),

wherein R 1 represents one selected from the group consisting of a hydrogen atom, a substituted alkyl group having from 1 to 6 carbon atoms and an unsubstituted alkyl group having from 1 to 6 carbon atoms, each of R 2 to R 6 independently represents one selected from the group consisting of a hydrogen atom, a substituted alkyl group having from 1 to 6 carbon atoms and an unsubstituted alkyl group having from 1 to 6 carbon atoms, respective substituent groups on the adjacent carbon atom may be linked each other to form a cyclic structure, and Y represents a divalent linking group.

5 . The aspherical-polymer fine particles as claimed in claim 1 , wherein the at least one radical polymerizable monomer is a monomer having at least two ethylene unsaturated bonds in the molecule thereof, the at least two ethylene unsaturated bonds being identical with reactivity.

6 . A method for producing aspherical-polymer fine particles, which comprises a radically polymerizing process,

wherein

the radically polymerizing process comprises:

a dissolving a resin for dispersal stabilization and at least one compound in a non-aqueous solvent, the at least one compound having at least two polymerizable groups in one molecule;

an adding a radical polymerizing initiator to the non-solvent; and

a heating the non-aqueous solvent.

7 . A method for producing aspherical-polymer fine particles, which comprises a first radically polymerizing process and a second radically polymerizing process,

wherein

(1) the first radically polymerizing process comprises:

a dissolving a resin for dispersal stabilization and radical polymerizable monomers in a non-aqueous solvent so as to provide a first mixture;

an adding a radical polymerizing initiator to the first mixture; and

a heating the first mixture,

(2) the second radically polymerizing process comprises:

an adding a radical polymerizing initiator and at least one compound in a non-aqueous solvent, the at least one compound having at least two polymerizable groups in one molecule, to the dispersal solution including the fine particles so as to provide a second mixture; and

a heating the second mixture.

8 . An ink composition comprising aspherical-polymer fine particles described in claim 1 .

9 . A method for producing lithographic printing plate, which comprises;

a discharging an ink composition described in claim 8 onto a hydrophilic substrate; and

a radiating an active radiation to the ink composition so that a hydrophobic image is formed on the hydrophilic substrate.

10 . An electrophoretic particle composition comprising: aspherical-polymer fine particles described in claim 1 , a non-aqueous solvent, and a charge adjusting agent.