Disclosed is the use of mixtures comprising at least 2 structurally different bis(biphenyl)triazine derivatives of formula (1) wherein X is hydrogen； C1-C50alkyl which may be uninterrupted or interrupted by one or more oxygen atoms and/or substituted by one or more R8 groups； C3-C12-cycloalkyl which is substituted by R8； -CH((CH2)p-R8)-CO-0-(CH2)m-R9； -CH((CH2)p-R8)-CO-(NR10)-(CH2)m-R9； (a)； (b)； -CO-(CH2)p-R8； -CO-O-(CH2)p-R8； -CH2-CH(-O(CO)-R8)-R9； -CO-(NR10)-(CH2)P-R8； C6-C20aryl； allyl； C4-C50alkenyl which is uninterrupted or is interrupted by one or more oxygen atoms； C3-C12cycloalkyl which is uninterrupted or interrupted by one or more oxygen atoms； C3-C20alkynyl； C6-C12cycloalkynyl； R1 is hydrogen； unsubstituted or substituted C1-C12alkyl； unsubstituted or substituted C3-C12cycloalkyl； unsubstituted or substituted C6-C20aryl； unsubstituted or substituted C2-C20alkenyl； OR7； OH； SR8； SOR7； SO2R7； SO3H； SO3M； or a radical of the formula (c)； R2, R3, R4, R5 and R6 independently of one another are hydrogen； hydroxyl； -CN； substituted or unsubstituted C1-C20alkyl； unsubstituted or substituted C3-C12-cycloalkyl； unsubstituted or substituted C1-C18alkoxy； unsubstituted or substituted C4-C20cycloalkoxy； C7-C20phenylalkyl； halogen； halo-C1-C5alkyl； sulfonyl； carboxyl； acylamino； acyloxy； C1-C12alkoxycarbonyl； aminocarbonyl； R7 is substituted or unsubstituted C1-C18alkyl； unsubstituted or substituted C3-C12- cycloalkyl； unsubstituted or substituted C6-C20aryl； unsubstituted or substituted C2-C20alkenyl； or C7-C20phenylalkyl； M is alkali metal； R8 and R9 independently of one another are Rx if attached to a carbon atom and are Ry if attached to an oxygen atom； p is 0 to 20； m is 0 to 20； Rx is hydrogen； hydroxyl； C1-C30alkyl； C3-C12cycloalkyl； C1-C30alkoxy； C3-C12cycloalkoxy； C3-C12cycloalkyl or C3-C12cycloalkoxy which is interrupted by one or more oxygen atoms； C6-C12aryl； hetero-C3-C12aryl； -ORz； NHRZ； Rz； CONR10R11； SO3H； SO3M； OSO3H2； allyl, C2-C30alkenyl； C4-C12-cyc
