Abstract A liquid developer for electrophotography, which is prepared by dispersing, in a suitable carrier liquid, either independently or together with a surface active agent, a toner which is obtained by the so-called graft-copolymerization technique by a direct chemical bonding between a pigment and unsaturated compounds having a dispersing effect and a large electric charge polarity controlling ability, or more specifically, unsaturated compounds capable of chemically bonding to pigment, resulting in a large and distinct electric charge polarity of said toner in the carrier liquid and also capable of facilitating the dispersion of said particles in said carrier liquid which consists of a paraffinic hydrocarbon (including both isoparaffinic and paraffinic hydrocarbons) having a relatively high-electric resistance and a low-dielectric constant.
A liquid developer for electrophotography according to claim 1, wherein said toner is dispersed in said carrier liquid together with only a small amount of at least one surface active agent selected from the group consisting of stearic acid, palmitic acid, naphthenic acid and aluminum, caDmium, cobalt, nickel, manganese, chromium and copper salts of an acid selected from the group consisting of stearic acid, palmitic acid and naphthenic acid.
Claim 2
Dependent Claim
72 words
A liquid developer for electrophotography according to claim 1, wherein said toner consists of a product of a graft-copolymerization reaction between said pigment and a mixture consisting of said unsaturated compound expressed by said formula (a) and said another unsaturated compound expressed by said formula (b), said mixture being of an (a) to (b) mol ratio wherein the ratio of (b) is not in excess of 4 to 6 mols of (a).
Claim 3
Dependent Claim
70 words
A liquid developer for electrophotography according to claim 1, wherein said toner consists of a product of a reaction obtained from a mixture consisting of said unsaturated compound expressed by said general formula (a) and said another unsaturated compound expressed by said general formula (b), said mixture being added with said pigment in an amount ranging from 25 to 50 percent by weight of the total weight of said mixture.
Claim 4
Dependent Claim
138 words
The method of forming a liquid developer for electrophotography according to claim 1, comprising forming a mixture of a member of the group consisting of laurylmethacrylate and isoctylmethacrylate, and a member of the group consisting of Beta -dimethylaminoethylmethacrylate, acrylonitrile, acrylic acid and hydroxymethacrylate in the molal ratio of 6 mols of the former to not more than 4 mols of the latter, adding a pigment from the group consisting of aniline black and carbon black to the mixture in the amount of 25 to 50 percent by weight of the total weight of the mixture, a catalytic amount of polymerization initiator, and a hydrocarbon solvent, heating the mixture in the range of about 100* to 120* C. for a sufficient time to obtain a pigment graft-copolymer, milling said copolymer and dispersing the milled copolymer in a hydrocarbon solvent.