Thermographic copy sheets and process

Claim 2

HEAT-SENSITIVE COPY FILM FOR PROJECTION TRANSPARENCY USE COMPRISING A THIN CLEAR PLASTIC FILM FOUNDATION HAVING THEREON TWO SUPERPOSED CLEAR RESINUOUS LAYERS WHICH DO NOT MELT UNDER CONDITIONS OF USE, ONE LAYER COMPRISING A SUBSTANTIALLYCOLORLESS ACID-SENSITIVE DYE PRECURSOR DISSOLVED IN A RESINOUS BINDER FORM THE GROUP CONSISTING OF VINYL CHLORIDE POLYMERS AND MIXTURES OF VINYL CHLORIDE POLYMERS AND OF VINYLIDENE CHLORIDE POLYMERS WITH FROM ABOUT 25 PERCENT UP TO 95 PERCENT BY WEIGHT OF ANOTHER COMPATIBLE MODIFYING RESIN, AND THE OTHER LAYER CONSISTING ESSENTIALLY OF A SUBSTANTIALLY-COLORLESS HEAT-VAPORIZABLE AROMATIC ACID DISSOLVED IN AN ALCOHOL-SOLUBLE RESINOUS BINDER COMPRISING A MIXTURE OF CELLULOSE ACETATE BUTYRATE AND POLYVINCYL BUTYRAL, WHICH MIXTURE IS SUBSTANTIALLY INCOMPATIBLE WITH THE RESINOUS BINDER MATERIAL OF THE SAID ONE LAYER.

Claim 3

Heat-sensitive copy film according to claim 1 in which the resinous binder for the dye precursor comprises a mixture of a minor amount by weight of a copolymer of vinylidene chloride and acrylonitrile and a major amount by weight of a styrene copolymer.

Claim 4

Heat-sensitive copy film according to claim 1 in which the dye precursor and the aromatic acid are present in amounts equal to from about 2 percent up to 15 percent by weight of the total weight of their respective layers.

Claim 5

Heat-sensitive copy film according to claim 1 in which the superposed layers are each present in a weight of from about 1 to 5 pounds per 3,000 square feet of said film.

Claim 6

Process of producing a heat-sensitive copy film for projection transparency use comprising the steps of: a. coating a thin clear plastic film foundation with a first composition comprising a substantially-colorless acid-sensitive dye precursor, a resinous binder material in which said dye precursor is soluble and which is selected from the group consisting of vinyl chloride polymers and mixtures of vinyl chloride polymers and of vinylidene chloride polymers with from about 25 percent to 95 percent by weight of another compatible modifying resin, and a volatile organic solvent for said dye precursor and for said resinous binder material and which is a non-solvent for said film foundation, b. evaporating said solvent to form a clear resinous base layer which does not melt under conditions of use, c. coating said base layer with a second composition consisting essentially of a substantially colorless heat-vaporizable aromatic acid, an alcohol-soluble resinous binder material comprising a mixture of cellulose acetate butyrate and polyvinyl butyral in which mixture said acid is soluble and which mixture is substantially incompatible with the resinous binder material of the base layer, and an alcohol solvent for said acid and resinous binder material which is a non-solvent for the dye precursor and for the resinous binder material of said base layer, and d. evaporating said solvent to form a clear resinous supercoating which does not melt under conditions of use.

Claim 7

Process of producing a heat-sensitive copy film for projection transparency use comprising the steps of: a. coating a thin clear plastic film foundation with a first composition comprising a substantially-colorless acid-sensitive dye precursor, a resinous binder material in which said dye precursor is soluble and which is selected from the group consisting of vinyl chloride polymers and mixtures of vinyl chloride polymers and of vinylidene chloride polymers with from about 25 percent to 95 percent by weight of another compatible modifying resin, and a volatile organic solvent for said dye precursor and for said resinous binder material and which is a non-solvent for said film foundation, b. evaporating said solvent to form a clear resinous base layer which does not melt under conditions of use, c. coating said base layer with a second composition consisting essentially of a substantially colorless heat-vaporizable aromatic acid, an alcohol-soluble resinous binder material comprising a mixture of cellulose acetate butyrate and polyvinyl butyral in which mixture said acid is soluble and which mixture is substantially incompatible with the resinous binder material of the base layer, and an alcohol solvent for said acid and resinous binder material which is a non-solvent for the dye precursor and for the resinous binder material of said base layer, and d. evaporating said solvent to form a clear resinous supercoating which does not melt under conditions of use.

Claim 8

Process according to claim 5 in which the base layer and the supercoating have a weight of from about 1 to 5 pounds per 3,000 square feet of the film.

Claim 9

Process according to claim 5 in which the resinous binder material of the base layer comprises a mixture of a minor amount by weight of a copolymer of vinylidene chloride and acrylonitrile and a major amount by weight of a styrene copolymer.

Claim 10

Process according to claim 5 in which the dye precursor and the aromatic Acid are present in amounts equal to from about 2 percent up to 15 percent by weight of the total dry weight of their respective layers.