| 摘要 |
<p>This invention provides transparent thermographic recording films which exhibit good anti-stick properties, are scratch resistant and substantially craze-free. The thermographic recording films comprise a transparent support carrying (a) a dye image-forming system comprising a di- or triarylmethane thiolactone dye precursor, an organic silver salt, a heat-fusible organic acidic material, and polyvinylbutyral as the binder; and, (b) a protective topcoat layer positioned above said dye image-forming system and comprising a water-insoluble polymeric binder, a mixture of at least two colloidal silicas having different average particle diameters in the proportion, by weight, of 1 part of silica having an average diameter of 50 nm or smaller and 0.3 to 1 part of silica particles having an average diameter no more than 40% of the larger sized silica particles, the ratio of total silica to binder being at least 3 parts per weight silica to 1 part per weight binder. One of the colloidal silicas may be a fumed colloidal silica. An organofunctional silane may be added to the protective topcoat layer or coated as a separate layer on top of the protective topcoat layer.</p> |
