Method of producing a photographic copolymer coupler

A method of producing a photographic copolymer coupler having at least two monomers as constitutional components:

• a monomer component A and a monomer component B, comprising carrying out a polymerization while adding, dropwise, a solution of the monomer component B dissolved in a non-aqueous solvent having a boiling point of 55° C. to 120° C., to a solution of the monomer component A dissolved in a non-aqueous solvent having a boiling point of 55° C. to 120° C., in the presence of a polymerization initiator,
• wherein the said monomer component B is a monomer coupler represented by the following formula (I), (II), or (III):
• wherein R represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, or a chlorine atom;
• X represents —CONH—, —NH—, —NHCONH—, or —NHCOO—;
• Y represents —CONH— or —COO—;
• A represents an unsubstituted or substituted straight-chain or branched alkylene group, or an unsubstituted or substituted phenylene group;
• Ar represents an unsubstituted or substituted phenyl group;
• Za, Zb, Zc, and Zd each represent methine, substituted methine, or —N═;
• and m and n are each 0 or 1;
• wherein R1 represents a hydrogen atom, a chlorine atom, an alkyl group, or aryl group;
• L1 represents —C(═O)N(R2)—, —C(═O)O—, —N(R2)C)═O)—, —OC(═O)—, formula (IV), formula (V), or formula (VI), shown below, in which R2 represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group;
• L2 represents a divalent linking group to link L1 and Q1, i is 0 or 1, j is 0 or 1, and Q1 represents a yellow coupler residue capable of forming a yellow dye upon coupling with an oxidation product of an aromatic primary amine developing agent;
• wherein R3 has the same meaning as R1, L3 has the same meaning as L1, L4 has the same meaning as L2, g has the same meaning as i, h has the same meaning as j, and Q2 represents a cyan coupler residue capable of forming a cyan dye upon coupling with an oxidation product of an aromatic primary amine developing agent;
• wherein R4 represents a substituent, R5 has the same meaning as R2, and k represents an integer of 0 to 4,
• wherein the said monomer component A is a non-color-forming monomer.