Electrographic recording material

Claim 1

An electrographic recording material comprising a conductive sheet support coated on at least one side with an electrically insulating layer comprising an intimate blend of a polymeric binder and up to 500 parts by weight of a finely divided pigment per 100 parts by weight of polymeric binder wherein the polymeric binder comprises an intimate blend of from about 40 to about 90 parts by weight of a polyvinyl acetal and from about 10 to about 60 parts by weight of a polystyrene or poly(α-methylstyrene) of molecular weight in the range of about 500 to about 1500, wherein the poly(vinyl acetal) is an interpolymer of a C 5 to C 9 vinyl acetal, a C 4 to C 10 vinyl carboxylate and vinyl alcohol, of weight average molecular weight in the range of about 20,000 to 500,000, comprising less than about 30 weight percent vinyl carboxylate units and from about 5 to about 21 weight percent of vinyl alcohol units.

Claim 10

A method of producing an electrographic recording material which comprises applying to a conductive sheet support a dispersion of a finely divided pigment in an organic solvent solution of an insulating polymeric binder and evaporating the solvent to form a continuous insulating layer in adherent contact with the conductive sheet support, wherein the insulating polymeric binder comprises from about 40 to about 90 parts by weight of a poly(vinyl acetal) polymer and from about 10 to about 60 parts by weight of a polystyrene or poly(α-methylstyrene) of molecular weight in the range of about 500 to about 1500 and wherein the poly(vinyl acetal) is an interpolymer of a C 5 to C 9 vinyl acetal, a C 4 to C 10 vinyl carboxylate and vinyl alcohol, of weight average molecular weight in the range of about 20,000 to 500,000, comprising less than about 30 weight percent vinyl carboxylate units and from about 5 to about 21 weight percent of vinyl alcohol units.

Claim 11

A method of producing an electrographic recording material which comprises applying to a conductive sheet support a dispersion of a finely divided pigment in an organic solvent solution of an insulating polymeric binder and evaporating the solvent to form a continuous insulating layer in adherent contact with the conductive sheet support, wherein the insulating polymeric binder comprises from about 40 to about 90 parts by weight of a poly(vinyl acetal) polymer and from about 10 to about 60 parts by weight of a polystyrene or poly(α-methylstyrene) of molecular weight in the range of about 500 to about 1500 and wherein the poly(vinyl acetal) is an interpolymer of a C 5 to C 9 vinyl acetal, a C 4 to C 10 vinyl carboxylate and vinyl alcohol, of weight average molecular weight in the range of about 20,000 to 500,000, comprising less than about 30 weight percent vinyl carboxylate units and from about 5 to about 21 weight percent of vinyl alcohol units.

Claim 12

A method of electrographic recording comprising forming an electrostatic charge pattern on an electrically insulating layer of an electrographic recording medium, developing the charge pattern by application of a toner and fixing the toner by heat or pressure, wherein the electrically insulating layer comprises an intimate blend of a polymeric binder and up to 500 parts by weight of a finely divided pigment per 100 parts by weight of polymeric binder, wherein the polymeric binder comprises from about 40 to about 90 parts by weight of poly(vinyl acetal) and from about 10 to about 60 parts by weight of poly(vinyl acetal) and from about 10 to about 60 parts by weight of a polystyrene or poly(α-methylstyrene) of molecular weight in the range of about 500 to about 1500 and wherein the poly(vinyl acetal) is an interpolymer of a C 5 to C 9 vinyl acetal, a C 4 to C 10 vinyl carboxylate and vinyl alcohol, of weight average molecular weight in the range of about 20,000 to 500,000, comprising less than about 30 weight percent vinyl carboxylate units and from about 5 to about 21 weight percent of vinyl alcohol units.

Claim 13

A method of electrographic recording comprising forming an electrostatic charge pattern on an electrically insulating layer of an electrographic recording medium, developing the charge pattern by application of a toner and fixing the toner by heat or pressure, wherein the electrically insulating layer comprises an intimate blend of a polymeric binder and up to 500 parts by weight of a finely divided pigment per 100 parts by weight of polymeric binder, wherein the polymeric binder comprises from about 40 to about 90 parts by weight of poly(vinyl acetal) and from about 10 to about 60 parts by weight of poly(vinyl acetal) and from about 10 to about 60 parts by weight of a polystyrene or poly(α-methylstyrene) of molecular weight in the range of about 500 to about 1500 and wherein the poly(vinyl acetal) is an interpolymer of a C 5 to C 9 vinyl acetal, a C 4 to C 10 vinyl carboxylate and vinyl alcohol, of weight average molecular weight in the range of about 20,000 to 500,000, comprising less than about 30 weight percent vinyl carboxylate units and from about 5 to about 21 weight percent of vinyl alcohol units.