Dimeric azo pyridone colorants

Compounds of the formula

• wherein (A) R1 is (i) an alkylene group, (ii) an arylene group, (iii) an arylalkylene group, (iv) an alkylarylene group, (v) an alkyleneoxy group, (vi) an aryleneoxy group, (vii) an arylalkyleneoxy group, (viii) an alkylaryleneoxy group, (ix) a polyalkyleneoxy group, (x) a polyaryleneoxy group, (xi) a polyarylalkyleneoxy group, (xii) a polyalkylaryleneoxy group, (xiii) a heterocyclic group, (xiv) a silylene group, (xv) a siloxane group, (xvi) a polysilylene group, or (xvii) a polysiloxane group, (B) R2 and R2′ each, independently of the other, is (i) an alkyl group, (ii) an aryl group, (iii) an arylalkyl group, (iv) an alkylaryl group, (v) an alkoxy group, (vi) an aryloxy group, (vii) an arylalkyloxy group, (viii) an alkylaryloxy group, (ix) a polyalkyleneoxy group, (x) a polyaryleneoxy group, (xi) a polyarylalkyleneoxy group, (xii) a polyalkylaryleneoxy group, (xiii) a heterocyclic group, (xiv) a silyl group, (xv) a siloxane group, (xvi) a polysilylene group, (xvii) a polysiloxane group, or (xviii) a group of the formula
• wherein r and s are each, independently of the other, integers representing a number of repeat —CH2— groups, (C) R3 and R3′ each, independently of the other, is (i) an alkyl group, (ii) an aryl group, (iii) an arylalkyl group, or (iv) an alkylaryl group, (D) X and X′ each, independently of the other, is (i) a direct bond, (ii) an oxygen atom, (iii) a sulfur atom, (iv) a group of the formula —NR40— wherein R40 is a hydrogen atom, an alkyl group, an aryl group, an arylalkyl group, or an alkylaryl group, or (v) a group of the formula —CR50R60— wherein R50 and R60 each, independently of the other, is a hydrogen atom, an alkyl group, an aryl group, an arylalkyl group, or an alkylaryl group, and (E) Z and Z′ each, independently of the other, is (i) a hydrogen atom, (ii) a halogen atom, (iii) a nitro group, (iv) an alkyl group, (v) an aryl group, (vi) an arylalkyl group, (vii) an alkylaryl group, (viii) a group of the formula
• wherein R70 is an alkyl group, an aryl group, an arylalkyl group, an alkylaryl group, an alkoxy group, an aryloxy group, an arylalkyloxy group, an alkylaryloxy group, a polyalkyleneoxy group, a polyaryleneoxy group, a polyarylalkyleneoxy group, a polyalkylaryleneoxy group, a heterocyclic group, a silyl group, a siloxane group, a polysilylene group, or a polysiloxane group, (ix) a sulfonyl group of the formula —SO2R80 wherein R80 is a hydrogen atom, an alkyl group, an aryl group, an arylalkyl group, an alkylaryl group, an alkoxy group, an aryloxy group, an arylalkyloxy group, an alkylaryloxy group, a polyalkyleneoxy group, a polyaryleneoxy group, a polyarylalkyleneoxy group, a polyalkylaryleneoxy group, a heterocyclic group, a silyl group, a siloxane group, a polysilylene group, or a polysiloxane group, or (x) a phosphoryl group of the formula —PO3R90 wherein R90 is a hydrogen atom, an alkyl group, an aryl group, an arylalkyl group, an alkylaryl group, an alkoxy group, an aryloxy group, an arylalkyloxy group, an alkylaryloxy group, a polyalkyleneoxy group, a polyaryleneoxy group, a polyarylalkyleneoxy group, a polyalkylaryleneoxy group, a heterocyclic group, a silyl group, a siloxane group, a polysilylene group, or a polysiloxane group.