Liquid developer for electrostatic photography

Claim 1

A liquid developer for electrostatic photography comprising resin grains dispersed in a non-aqueous solvent having an electric resistance of at least 10 9 Ω cm and a dielectric constant of not higher than 3.5, wherein the dispersed resin grains are polymer resin grains obtained by polymerizing a solution containing at least one monofunctional monomer (A) which is soluble in the said non-aqueous solvent but becomes insoluble in said non-aqueous solvent by being polymerized, in the presence of a dispersion-stabilizing resin which is soluble in said non-aqueous solvent and is a comb-like copolymer having a polymer main chain, said comb-like copolymer formed from (1) at least a mono-functional macromonomer (M) having a weight average molecular weight of from 1×10 3 to 2×10 4 and (2) at least a monomer represented by the following formula (III), said mono-functional macromonomer (M) having (i) a polymer main chain containing at least one polymer component represented by the following formula (IIa) or (IIb) and (ii) a polymerizable double bond group represented by the following formula (I) bonded to only one terminal of the polymer main chain of the macromonomer (M); ##STR126## wherein V represents --COO--, --OCO--, CH 2 m OCO--, CH 2 m COO--, --O--, --CONHCOO--, --CONHCO, --SO 2 --, --CO--, ##STR127## (wherein Z 1 represents a hydrogen atom or a hydrocarbon group and m represents an integer of from 1 to 3); a 1 and a 2 , which may be the same or different, each represents a hydrogen atom, a halogen atom, a cyano group, a hydrocarbon group, --COO--Z 2 , or --COO--Z 2 bonded via a hydrocarbon group (wherein Z 2 represents a hydrogen atom or a hydrocarbon group which may be substituted); ##STR128## wherein X° has the same meaning as V in formula (I); Q° represents an aliphatic group having from b 1 to 22 carbon atoms or an aromatic group having from 6 to 12; Q represents --CN or ##STR129## wherein Y represents a hydrogen atom, a halogen atom, an alkoxy group, or --COOZ 3 (wherein Z 3 represents an alkyl group, an aralkyl group, or an aryl group); and b 1 and b 2 , which may be the same or different, have the same meanings as a 1 and a 2 in formula (I); ##STR130## wherein X 1 has the same meaning as X° in formula (IIa); Q 1 has the same meaning as Q° in formula (IIa); and d 1 and d 2 , which may be the same or different, have the same meanings as a 1 and a 2 in formula (I); with the proviso that, in the component of the macromonomer (M) represented by formula (IIa) and in the component of the monomer represented by formula (III), at least one of Q° and Q 1 represents an aliphatic group having form 10 to 22 carbon atoms, wherein the proportion of the mono-functional macromonomer (M) as a copolymer component of the comb-like copolymer is from 1% by weight to 70% by weight based on the weight of the copolymer; and wherein the content of the monomer shown by formula (III) is from 30% by weight to 99% by weight based on the weight of the copolymer.