Abstract: A liquid developer composition for rendering visible electrostatically charged areas. The composition contains in an electrically insulating non-polar carrier liquid having a volume resistivity of at least 10.sup.9 ohm.cm and a dielectric constant less than 3, dispersed coloring matter acting as toner particles and at least one onium salt polymer including recurring units incorporating an onium group together with an anion.

Abstract: A liquid electrophoretic developer composition suitable for rendering visible electrostatically charged areas, which composition contains in an electrically insulating non-polar organic carrier liquid having a volume resistivity of at least 10.sup.9 ohm.cm and a dielectric constant less than 3, pigment particles carrying at least one substance conferring electric charges on said particles, dispersed with the aid of a block copolymer containing one adsorbent group A and at least one solvatable group B, characterized in that said group A represents a polystyrene chain having a number average molecular weight of at least 2,000, and said group B represents a polymethacrylate fatty alcohol ester chain having a number average molecular weight of at least 7,000. The adsorption of said block copolymer to pigment particles is illustrated in FIG. 1.

Abstract: An electrostatic liquid developer for the development of electrostatic charge patterns comprises an electrically insulating carrier liquid having a dielectric constant of less than 3 and a volume resistivity in excess of 10.sup.9 Ohm.cm. In this electrically insulating carrier liquid are dispersed resin-precoated toner particles formed of a pigment or coloring agent precoated with a polymer of an acrylic or methacrylic acid ester of hydrogenated abietyl alcohol.

Abstract: A liquid developer composition suitable for use in developing electrostatic charge patterns, which composition contains in an electrically insulating non-polar carrier liquid a dispersed particulate coloring substance, at least one charge control substances, a copolymer (I) precoating the coloring substance particles in a weight ratio of copolymer (I) to coloring substance between 1:1 and 9:1 and a copolymer (II) in the carrier liquid in a weight ratio of copolymer (II) to coloring substance between 0.5:1 and 5:1,Said copolymer (I) being a copolymer consisting of 50 to 90 mole % of recurring units of the following formula (A) ##STR1## wherein X is phenyl or alkylphenyl, and from 10 to 50 mole % of recurring units of the following formula (B) ##STR2## wherein R is a hydroxyl group or is a group resulting from the esterification of hydroxyl by means of a C.sub.12 -C.sub.20 aliphatic acid with the proviso that the copolymer (I) contains at least 0.

Abstract: A liquid developer composition suitable for rendering visible in the direct or reversed sense electrostatic charge patterns contained on a surface, which composition contains in a hydrocarbon liquid having a volume resistivity of at least 10.sup.9 Ohm.cm and a dielectric constant of less than 3, a negatively charged suspended toner comprising pigment particles bearing organic polymeric material on their surfaces and at least one organic ionic surfactant, wherein(1) said organic ionic surfactant is an oil-soluble overbased alkaline earth metal hydrocarbon sulphonate wherein the alkaline earth metal is magnesium, calcium or barium, the sulphonate has an average molecular weight of at least 800, and the total base number (TBN) of the surfactant determined according to ASTM D 664-58 is at least 2, and(2) the polymeric material is a copolymer of (A) a C.sub.12 -C.sub.

Abstract: A liquid toner developer composition suitable for use in developing electrostatic charge patterns, characterized in that the developer contains a metal alkyl sulphonate ionic surfactant in which the metal ion is a bivalent metal ion selected from the group consisting of zinc(II), lead(II), cadmium(II) and copper(II) and the sulphonate group thereof is present directly on an alkyl chain containing at least 6 carbon atoms in a straight chain, which sulphonate has a positive charging effect on the toner, and the sizes of the toner particles and the amount in which said sulphonate is present are selected such that the toner can develop a charge pattern having a charge level corresponding to 50 V for a capacitance of 1.5.times.10.sup.-11 F.cm.sup.-2 up to an optical density of at least 0.8.

Abstract: A liquid developer composition suitable for use in developing electrostatic charge patterns, which composition contains in an electrically insulating carrier liquid having a volume resistivity of at least 10.sup.9 Ohm.multidot.cm and a dielectric constant below 3, a dispersed particulate coloring substance bearing one or more charge control substances and an organic polymeric material, wherein said polymeric material is a copolymer containing the following recurring units (A) and (B) or (A) and (C): ##STR1## wherein: R represents hydrogen or an alkyl group of 1 to 4 carbon atoms,R.sup.1 represents hydrogen or an acyl group,R.sup.2 represents hydrogen or carboxyl in free acid or salt form,R.sup.3 represents hydroxyl or an ether group,A represents an alkylene chain of 12 to 20 carbon atoms,Y.sup.1 represents --CO--O--CH.sub.2 --CHOH--CH.sub.2 --Y.sup.2 represents --CO--, andx represents 4 to 20.