| 摘要 |
<p>A dyestuff capable of undergoing a clearly visible colour change when contacted with a colour-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 colour-developing chemical to produce a coloured mark on the package. The dyestuff is preferably a latent dyestuff which is colourless and invisible to the eye under ambient conditions for use of the film but which forms a clearly visible colour when contacted with the colour-developing material.</p> |
