Agfa Gevaert Nv

Noel J De Volder

Yvan K Gilliams

Walter F De Winter

Jozef Leonard Van Engeland

Herman J Uytterhoeven

Bernard H Tavernier

Daniel M Timmerman

Robert J Pollet

August M Marien

Francis J Sels

Albert Lucien Poot

Nikolaas C De Jaeger

Jan J Priem

Jan Frans Van Besauw

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. The anion has at least one of the following characteristics:

Liquid developer for development of electrostatic images comprising

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.

Liquid electrophoretic developer

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.

Electrophotographic liquid developer comprising acrylic or methacrylic

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,

Electrophoretic developers

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

Electrophoretic development

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.

Electrophoretic liquid developer containing a metal alkyl sulphonate

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,

A liquid toner composition comprising carrier liquid and toner particles for the development of electrostatic charge patterns is described wherein the said liquid comprises (1) a bivalent or trivalent metal salt of an oxyacid derived from phosphorus containing at least one organic residue and (2) one or more members selected from the group consisting of amines, polyurethans and alkylated polymers of a heterocyclic N-vinyl monomer. By means of the materials (1) and (2) the polarity of the toner particles can be controlled to obtain optimum image density and contrast. When carbon blacks are used as toner material it is possible to control the polarity to obtain either positive-working or negative-working toner compositions.

Liquid electrophotographic developers

A developing material for use in the development of electrostatic images comprising toner particles and carrier particles is described wherein the developing material incorporates at least one solid hydrophobic bivalent or trivalent metal salt of a half-ester of a branched-chain or straight-chain aliphatic dicarboxylic acid and/or at least one bivalent or trivalent metal salt of a monoester or diester of a phosphorus oxyacid. The images obtained by means of this developing material have an improved image contrast, solid area coverage and surface smoothness. The toner particles show less tendency to cake and agglomerate and have improved mechanical strength. Cleaning of the imaging surface between use and re-use is also facilitated.

Development of electrostatic images

An electrostatic toner material for use in electrophotography consisting essentially of finely divided particles formed of a generally uniform mixture comprised of 5 to 15 % by weight of a colored material and 95 to 85 % by weight of resin mixture consisting essentially of:

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Edegem, Belgium

Noel J De Volder