A method for preparing a printing plate by an inkjet process consisting essentially of discharging an oily ink using an electrostatic field on a lithographic printing plate precursor comprising a water-resistant support having provided thereon an image receiving layer having a lithographically printable hydrophilic surface dropwise from a head having a discharge electrode to form an image on the lithographically printable hydrophilic surface, wherein the oily ink comprises resin particles dispersed in a nonaqueous carrier liquid having an electric resistance of 109 Ωcm or more and a dielectric constant of 3.5 or less, and said resin particles dispersed are copolymer particles obtained by polymerization granulation of a solution comprising (i), (ii) and (iii):
- (i) at least one monofunctional monomer (A) which is soluble in a nonaqueous solvent which is at least miscible with said nonaqueous carrier liquid and becomes insoluble therein by polymerization;
- (ii) (ii-a) at least one monomer (B) represented by the following formula (I-A) which is copolymerizable with said monomer (A), or
- (ii-b) at least one monofunctional macromonomer (MA) having a weight average molecular weight of 2×104 or less obtained by combining a polymerizable double bond group represented by the following formula (II-B) with only one end of a main chain of a polymer comprising a repeating unit corresponding to a monomer represented by the following formula (I-B);
- and
- (iii) at least one resin for dispersion stabilization (P) which is a polymer comprising a repeating unit represented by the following formula (III), wherein said polymer is crosslinked at a part of its main chain thereof, and said resin (P) is soluble in said nonaqueous solvent:
- wherein E1 represents an aliphatic group having 8 or more carbon atoms or a substituent having a total number of atoms of 8 or more, provided that hydrogen atoms directly attached to a carbon or nitrogen atom are excluded from the number, represented by the following formula (IV-A):
- wherein R21 represents a hydrogen atom or an aliphatic group having 1 to 18 carbon atoms;
- B1 and B2 are the same or different and each represents —O—, —S—, —CO—, —CO2—, —OCO—, —SO2—, —N(R22)—, —CON(R22)—, —N(R22)CO—, —N(R22)SO2—, —SO2N(R22)—, —NHCO2— or —NHCONH—, in which R22 has the same meaning as R21;
- A1 and A2 are the same or different and each represents at least one group selected from a group represented by the following formula (IV-Aa) and a hydrocarbon group having 1 to 18 carbon atoms, which each may be substituted, provided that, in the case where A1 or A2 represents two or more groups selected from a group represented by the following formula (IV-Aa) and a hydrocarbon group having 1 to 18 carbon atoms, A1 or A2 represents (1) two or more groups represented by formula (IV-Aa), (2) a combination of at least one group represented by formula (IV-Aa) and at least one hydrocarbon group having 1 to 18 carbon atoms, or (3) two or more hydrocarbon groups having 1 to 18 carbon atoms:
- wherein B3 and B4 are the same or different and each has the same meaning as B1 and B2;
- A4 represents a hydrocarbon group having 1 to 18 carbon atoms which may be substituted;
- R23 has the same meaning as R21;
- and
- m, n and p are the same or different and each represents an integer of 0 to 4, provided that m, n and p are not 0 at the same time;
- U1 represents —COO—, —CONH—, —CON(R11)—, —OCO—, —CONHCOO—, —CH2COO—, —(CH2)kOCO—, —O—, —C6H4— or —C6H4—COO—, in which R11 represents an aliphatic group or a substituent represented by formula (IV-A) described above, and k represents an integer of 1 to 4;
- and
- a1 and a2 are the same or different and each represents a hydrogen atom, an alkyl group, a halogen atom, a cyano group, —COO—R12 or —CH2COO—R12, in which R12 represents an aliphatic group:
- wherein V0 represents —COO—, —OCO—, —(CH2)rCOO—, —(CH2)rOCO—, —O—, —SO2—, —CONHCOO—, —CONHCONH—, —CON(D11)—, —SO2N(D11)— or a phenylene group, in which D11 represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, and r represents an integer of 1 to 4;
- a11 and a12 are the same or different and each represents a hydrogen atom, a halogen atom, a cyano group, a hydrocarbon group, —COO—D12 or —COO—D12 linked through a hydrocarbon group, in which D12 represents a hydrogen atom or a hydrocarbon group which may be substituted;
- D0 represents a hydrocarbon group having 8 to 22 carbon atoms or a substituent group having a total number of atoms of 8 or more, provided that hydrogen atoms attached to a carbon or nitrogen atom are excluded from the number, represented by the following formula (IV-B):
- wherein D21 represents a hydrogen atom or an aliphatic group having 1 to 22 carbon atoms;
- B11 and B12 are the same or different and each represents —O—, —CO—, —CO2—, —OCO—, —SO2—, —N(D22)—, —CON(D22)—, or —N(D22)CO—, in which D22 has the same meaning D21;
- A11 and A12 are the same or different and each represents at least one group selected from a group represented by the following formula (IV-Ba) and a hydrocarbon group having 1 to 18 carbon atoms, which each may be substituted, provided that, in the case where A11 or A12 represents two or more groups selected from a group represented by the following formula (IV-Ba) and a hydrocarbon group having 1 to 18 carbon atoms, A11 or A12 represents (1) two or more groups represented by formula (IV-Ba), (2) a combination of at least one group represented by formula (IV-Ba) and at least one hydrocarbon group having 1 to 18 carbon atoms, or (3) two or more hydrocarbon groups having 1 to 18 carbon atoms:
- wherein B13 and B14 are the same or different and each has the same meaning as B11 and B12;
- A14 represents a hydrocarbon group having 1 to 18 carbon atoms which may be substituted;
- D23 has the same meaning as D21;
- and
- m0, n0 and p0 are the same or different and each represents an integer of 0 to 4, provided that m0, n0 and p0are not 0 at the same time;
- wherein V1 represents —COO—, —CONHCOO—, —CONHCONH—, —CONH— or a phenylene group;
- and
- b11 and b12 are the same or different and each has the same meaning as a11 and a12 in formula (I-B);
- wherein X1 represents —COO—, —OCO—, —CH2OCO—, —CH2COO—, —O— or —SO2—;
- Y1 represents an aliphatic group having 10 to 32 carbon atoms;
- and
- b1 and b2 are the same or different and have the same meaning as a1 and a2 in formula (I-A) or a11 and a12 in formula (I-B);
- wherein the support has a specific electric resistance of 1010 Ωcm or less at least at an area directly under the image receiving layer,
- wherein said resin particles dispersed in the oily ink are electrically detectable particles positively or negatively charged,
- wherein the lithographically printable hydrophilic surface faces the discharge electrode, and a counter electrode is provided on the opposite side thereof.