Plastics film, use of dyestuffs therein and process for testing the authenticity of packaged goods

摘要

A dyestuff capable of undergoing a clearly visible colour change when contacted with a color-developing material is dispersed in the body of a plastics film and used in the identification of goods. The film can be used for packaging of the goods or as a label or seal affixed to the goods. When testing the authenticity of packaging goods, the plastics film is marked with the color-developing chemical to produce a colored mark on the package. The dyestuff is preferably a latent dyestuff which is colorless and invisible to the eye under ambient conditions for use of the film but which forms a clearly visible color when contacted with the color-developing material.