Multilayer electrophotographic element containing high contrast and opaque barrier layers

Claim 2

The invention as described in claim 1 wherein said optical barrier layer comprises carbon black particles.

Claim 3

The invention of claim 1 wherein said optical barrier layer comprises a light scattering titanium pigment, a resinous binder, and a dye present in an amount equal to about 20 to about 60 percent by weight based on the amount of resinous binder, said titanium pigment selected from the group consisting of titanium dioxide and titanium compounds having the formulas: I. MnTiO3 II. MnTiO4 III. MnTi2O5 wherein M is a metallic element selected from Groups I, II, III, and IV of the Periodic Table and n is an integer within the range of 1-4 depending on the valency of M.

Claim 4

A multilayer electrographic element comprising a transparent conductive support bearing (a) a photoconductive insulating layer, (b) an opaque optical barrier layer adjacent to said photoconductive insulating layer, and (c) a high contrast layer having a thickness of 1 to 50 microns adjacent to said optical barrier layer, said opaque optical barrier layer having a specific resistivity greater than about 1010 ohm-cm and comprising from about 10 to about 90 volume percent of finely-divided opaque pigment particles dispersed in a film-forming resinous binder, said optical barrier layer having no significant photoconductive properties and said high contrast layer having a specific resistivity greater than about 1010 ohm-cm and a dielectric constant from about 5 to about 50 and comprising a titanium pigment dispersed in a film-forming resinous binder wherein the high contrast layer comprises from about 30 to about 90 volume percent of the pigment, said particles of titanium pigment having a particle size of less than 5 microns and having a refractive index greater than the refractive index of said film-forming binder, said pigment selected from the group consisting of titanium dioxide and compounds having the formulas: I. MnTiO3 II. Mn TiO4 III. MnTiO5 wherein M represents a metallic element selected from Groups I, II, III and IV of the Periodic Table and n represents an integer within the range of from 1 to 4 depending on the valency of M, said titanium pigment having an average particle size less than about 0.5 microns.

Claim 5

The invention as described in claim 5 wherein said optical barrier layer contains a color balancing dye in an amount Equal to about 0.1 to about 10 weight percent based on the amount of resin binder and wherein said titanium pigment is selected from the group consisting of titanium dioxide, barium titanates, calcium titanates, lithium titanates, lead titanates, zinc titanates, and mixtures thereof.

Claim 6

The invention as described in claim 5 wherein said organic photoconductive insulating layer comprises an organic photoconductive material dispersed in a resinous film-forming binder and a co-crystalline complex of a polycarbonate resin and a pyrylium sensitizing dye.

Claim 7

The invention as described in claim 5 wherein said organic photoconductive insulating layer comprises an inorganic photoconductor.

Claim 8

A multilayer electrographic element comprising a transparent support bearing (a) a photoconductive insulating layer, (b) an opaque optical barrier layer adjacent to said photoconductive insulating layer, and (c) a high contrast layer having a thickness of less than 50 microns adjacent to said optical barrier layer, said optical barrier layer having a specific resistivity greater than about 1010 ohm-cm and comprising from about 10 to about 90 volume percent of finely-divided titanium pigment particles, 90 to about 10 volume percent of a film-forming resinous binder and 20 to 60 weight percent of a dye based on the amount of film-forming resinous binder, said optical barrier layer having no significant photoconductive properties and said finely-divided titanium pigment particles having a refractive index greater than the refractive index of said film-forming resinous binder, said high contrast layer having a specific resistivity greater than about 1010 ohm-cm and a dielectric constant from about 5 to about 50 and comprising titanium pigment particles dispersed in a film-forming resinous binder, wherein the high contrast layer comprises from about 30 to about 90 volume percent of the pigment, said particles of titanium pigment having a particle size of less than 5 microns and having a refractive index greater than the refractive index of said film-forming binder, said titanium pigment particles having an average particle size less than 0.5 microns and selected from the group consisting of titanium dioxide and compounds having one of the following formulas: I. MnTiO3 II. MnTiO4 and III. MnTiO5 wherein M is a metallic element selected from Groups I, II, III and IV of the Periodic Table and n is an integer within the range of from 1 to 4 depending on the valency of M.

Claim 9

The invention as described in claim 9 wherein said organic photoconductive insulating layer comprises an organic photoconductive material dispersed in a resinous film-forming binder and a co-crystalline complex of a polycarbonate resin and a pyrylium sensitizing dye.

Claim 10

The invention as described in claim 9 wherein said photoconductive insulating layer comprises an inorganic photoconductor.

Claim 11

The invention as described in claim 9 wherein the titanium pigment is selected from the group consisting of titanium dioxide, barium titanates, lithium titanates, calcium titanates, lead titanates, zinc titanates, and mixtures thereof.

Claim 12

In an electrographic element comprising a transparent conductive support bearing a photoconductive insulating layer, the improvement which comprises an optical barrier layer overlying said photoconductive layer and a high contrast layer having a thickness of 1 to 50 microns overlying said barrier layer, said optical barrier layer opaque to visible light, possessing a specific resistivity greater than about 1010 ohm-cm, and comprising finely-divided opaque particulate material dispersed in a film-forming resinous binder or light scattering particulate matter dispersed in a dyed film-forming resinous binder wherein the optical barrier layer comprises from about 10 to about 90 volume percent of the particulate matter; said optical barrier layer having no significant photoconductive properties and said finely-divided light scattering particulate matter having a refractive index greater than the refractive index of said film-forming resinous binder; said high contrast layer having a specific resistivity greater than about 1010 ohm-cm, a dielectric constant from about 5 to about 50, and comprising a finely-divided light-scattering particulate material dispersed in a film-forming resinous binder wherein the high contrast layer comprises from about 30 to about 90 volume percent of the particulate material, said finely-divided light-scattering particulate material having a particle size of less than 5 microns and having a refractive index greater than the refractive index of said resinous binder.

Claim 13

The invention as described in claim 13 wherein said high contrast layer comprises a resinous binder having a dielectric constant greater than about 5.0.

Claim 14

The invention as described in claim 13 wherein said high contrast layer comprises a finely-divided light-scattering particulate material having a dielectric constant greater than about 50.

Claim 15

The invention as described in claim 13 wherein said high contrast layer has a dry thickness within the range of from about 1 micron to about 50 microns and comprises a finely-divided light-scattering particulate material having a dielectric constant greater than about 50 and a particle size less than about 0.5 micron.

Claim 16

In an electrographic process wherein a visible image corresponding to an original image pattern of electromagnetic radiation is formed utilizing a photoconductive element comprising a transparent conductive support bearing a photoconductive insulating layer and an overcoat therefor, the electrographic element being exposed to said image pattern of electromagnetic radiation while the overcoat for said element is subjected to ambient light conditions, the improvement wherein said overcoat comprises an optical barrier layer overlying said photoconductive layer and a high contrast layer having a thickness of 1 to 50 microns overlying said barrier layer, said optical barrier layer opaque to visible light, possessing a specific resistivity greater than about 1010 ohm-cm, and comprising finely-divided opaque particulate material dispersed in a film-forming resinous binder or light-scattering particulate matter dispersed in a dyed resinous binder wherein the optical barrier layer comprises from about 10 to about 90 volume percent of the particulate material; said optical barrier layer having no significant photoconductive properties and said finely-divided light-scattering particulate material having a refractive index greater than the refractive index of said film-forming resinous binder; said high contrast layer having a specific resistivity greater than about 1010 ohm-cm, a dielectric constant from about 5 to about 50, and comprising a finely-divided light-scattering particulate material dispersed in a film-forming resinous binder wherein the high contrast layer comprises from about 30 to about 90 volume percent of the particulate material, said light-scattering particulate material having a particle size of less than 5 microns and having a refractive index greater than the refractive index of said film-forming resinous binder.