Patent ID: 7002021

Claim:
A diketopyrrolopyrrole of the formula (I) wherein R 1 , R 2 , R 3 and R 4 independently of one another are a C 1 –C 4 alkyl radical or a substituted or unsubstituted phenyl radical, wherein the substituted phenyl radical is substituted by 1, 2, 3 or 4 substituents selected from the group consisting of C 1 –C 4 alkyl, C 1 –C 4 alkoxy, CN, F, Cl, Br, NO 2 , CF 3 , S—C 1 –C 4 alkyl, phenyl and (C 1 –C 2 )alkylenephenyl, with the proviso that at least one of the radicals, R 1 , R 2 , R 3 , or R 4 , is a substituted or unsubstituted phenyl radical.