Colour-developing sheet for carbonless copying - contain layer of combination of solid acid with acidic polymer and titanium oxide

摘要

A colour developing sheet comprises a support and an electron-accepting layer consisting of a phenol-formaldehyde resin and a solid acid, which are capable of developing colour upon reaction with an electron-donating colourless dye. The novel feature is that the electron-accepting layer also contains Ti oxide. The use of rutile TiO2 and an active clay is pref. The ratio of resin to acid is pref. 1:2-16. The wt. ratio of TiO2 to resin may be 0.1-5, pref. 0.2-3:1. The sheet is useful in no-carbon copying processes. It is resistant to yellowing, and to fading of the developed image even if exposed to sun or fluorcscent lamp light or atmos. air for a long period; and has good printability.