Imaging media capable of displaying sharp indicia
First Claim
1. In sheet material of the type wherein a base sheet is coated on at least one face with a layer comprising a first organic polymer containing interconnected microvoids, said layer being locally transparentizable to display contrasting indicia when there is applied to its exposed surface a transparent, colorless liquid which has a refractive index similar to that of the solid constituents of the layer but which is a non-solvent for said first polymer,the improvement comprising, incorporated in said layer, a second organic polymer which has a solubility parameter differing from that of the liquid by about 2 hildebrands and which jellifies the liquid,whereby the indicia maintain substantially the same dimensions throughout the time that the layer is locally transparentized.
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Accused Products
Abstract
Improved sheet material of the type where a base sheet is provided with an opaque microvoid-containing layer which can be locally transparentized by applying a colorless liquid which is a non-solvent for the layer. Indicia remain more sharply defined by including in the layer an organic polymer which jellifies in the presence of the liquid and blocks lateral migration.
54 Citations
12 Claims
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1. In sheet material of the type wherein a base sheet is coated on at least one face with a layer comprising a first organic polymer containing interconnected microvoids, said layer being locally transparentizable to display contrasting indicia when there is applied to its exposed surface a transparent, colorless liquid which has a refractive index similar to that of the solid constituents of the layer but which is a non-solvent for said first polymer,
the improvement comprising, incorporated in said layer, a second organic polymer which has a solubility parameter differing from that of the liquid by about 2 hildebrands and which jellifies the liquid, whereby the indicia maintain substantially the same dimensions throughout the time that the layer is locally transparentized.
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12. Self-supporting sheet material which is substantially insensitive to marking by the localized application of heat or pressure but which is receptive to ink, pencil, crayon or similar markings and which is adapted to being temporarily or permanently provided with markings by the application of a colorless liquid, comprising in combination:
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a. a self-supporting base sheet, b. bonded over at least one side of the base sheet, a reflective opaque white to pastel layer having a cohesive value of at least 400 grams and consisting essentially of particles held in pseudo-sintered juxtaposition by a thermoset binder so that interconnected microvoids are present throughout the layer, and c. a jellifying organic polymer other than the binder partially filling said microvoids, whereby, when there are applied to the exposed surface of said layer desired indicia of a marking liquid which has a refractive index approximately that of the particles, a solubility parameter differing from that of said polymer by about 2 hildebrands, is a non-solvent for said binder and is jellified by the jellifying polymer, the liquid not only penetrates the microvoids and is jellified by the jellifying polymer, thereby reducing the reflectivity of the layer in the vicinity of the liquid-penetrated microvoids to impart transparency and maintaining substantially constant dimensions of the indicia throughout the time that the layer is locally transparentized, but also is inhibited from lateral wicking.
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Specification