Color changing composition and coloring polymeric articles made therefrom

THIS INVENTION RELATES TO colouring polymeric articles and materials for use therein. A process is provided for producing a polymeric layer having a desired image thereon or a three dimensional article comprising a number of such layers in which a layer of a liquid photocurable composition which comprises photo colorable particles is cured by light and selected areas thereof are irradiated with light of a different dose, thereby forming the desired image which composition comprises particles dispersed in it which are micro-capsules containing a photosensitive color changing composition within a barrier layer which is substantially impermeable to the components of the color changing composition or are solid particles comprising an immobilized photosensitive color changing composition. The process permits the use of the same initiating mechanism to cure the resin and to change the color of the particles.