Patent GB-1312776-A (GB)
Title: Manufacture of an electrostatic toner material
IPC: C08F291/00
Filed: 1969-07-25
Abstract: 1312776 Graft polymers AGFA-GEVAERT 19 June 1970 [25 July 1969] 37488/69 Heading C3G A process for the preparation of an electrostatic toner material for use in the development of electrostatic images, of the type comprising finely divided resin particles and a dyestuff or finely divided pigment; wherein the said resin particles are prepared by polymerization of (a) a solution in an inert organic solvent in a concentration of 15-85% by weight of at least one α,#-ethylenically unsaturated monomer, the polymers of which being insoluble in said inert organic solvent, (b) 1-10% by weight based on the weight of monomer(s) present of a non-ionic polymer (i.e. a polymer which does not contain ionizable groups) and which is also soluble in said inert organic solvent, and (c) 0À1-5% by weight based on the weight of monomer(s) present of a free radical-forming polymerization initiator, the polymerization being carried out at a temperature between 30‹ and 150‹ C. with continuous stirring until graft copolymers of said monomer(s) and of said non-ionic polymer are obtained, which are insoluble in said inert organic solvent and have a particle size of 1 to 10 Á, and adding either during or after the graft polymerization process a dyestuff or finely divided pigment in an amount 0À1-20% by weight based on the total weight of resin particles. The non-ionic polymer may be poly(n-butyl methacrylate), poly(isobutyl methacrylate), polybutadiene, polyisoprene, polyisobutylene, styrene-butadiene copolymers, ethylene-vinyl acetate copolymers, vinyl acetate-vinyl laurate copolymers, copolymers of vinyltoluene and n-butyl acrylate or n-butyl methacrylate, polystyrene, poly-N-vinylpyrrolidone, polyethylene oxide, ethyl cellulose, or copolymers of ethyl acrylate and not more than 20% butadiene. Suitable monomers are styrenes, methacrylates, acrylates, acrylonitrile, methacrylonitrile, vinyl chloride, butadiene, isobutylene, chlorobutadiene, 2-methylbutadiene and vinylidene chloride. Suitable polymerization initiators are "peroxy" compounds. Numerous organic solvents are also specified. The pigment or dyestuff may be incorporated into the graft polymer either by mixing therewith with the preformed copolymer or by carrying out the polymerization in the presence of the dyestuff or pigment. A particularly preferred method is carrying out the polymerization in the presence of an α,#-ethylenically unsaturated copolymerizable monomer dye or colour coupler. With the radically polymerizable dyestuffs a coloured graft copolymer is obtained directly whereas with the monomeric colour couplers the finally formed graft copolymer obtains its desired colour only by a suitable treatment after polymerization, e.g. diazotization. The specific examples refer to "toner material" produced from :-graft copolymer particles admixed with carbon black, viz. styrene and methyl methacrylate on polybutadiene admixed with carbon black (1,2), a mixture of (a) styrene and methyl methacrylate on butadiene-ethyl acrylate copolymer and (b) polyvinyl butyral admixed with carbon black (5); graft copolymerization carried out in the presence of a white pigment, viz. styrene and acrylonitrile on to styrene-butadiene copolymer (3), styrene and methyl methacrylate on to poly(N-vinyl pyrrolidone) (4), styrene and methyl methacrylate on to polyethylene oxide (10), and styrene, methyl methacrylate and acrylonitrile on to styrene-butadiene copolymer (11); coupling of a graft copolymer with incorporated colour coupler monomer of styrene, methyl methacrylate and 1-phenyl-3-methacryloylamino-5-pyrazolone on to butadieneethyl acrylate with a diazonium compound (6, 7); graft copolymer of styrene, methacrylate and poly(N-vinyl pyrrolidone) prepared in the presence of a coloured dyestuff (8) and in the presence of a copolymerizable monomer dye (9); and graft copolymer of styrene, methyl methacrylate and polyethyleneoxide prepared in the presence of a colour coupler. The preparation of specific graft copolymers is referred to in "Preparations", some of which by virtue of the process involved relate to the final coloured material employed as the toner material (15, 17, 18, 20).