Patent ID: 7659325

Claim:
Transparent polymer material containing at least one covalently attached dye, said dye having the general formula I: wherein each of R 1 , R 2 and R 3 is independently selected from hydrogen, sulfonate, nitro, halogen, nitril, phenyl, carboxylate, —(CH 2 ) n —X 1 —H and —X 2 —(CH 2 ) n —CH 3 , wherein X 1 is O, NH, CH 2 or S; X 2 is O, NH, S, S(═O) 2 , C(═O)O; and n is an integer in the range 0 to 20; or wherein two groups together with the C-atoms to which they are bound form a benzene ring; provided that at least one R 3 is a linker moiety L through which the dye is covalently bound to the polymer.