Patent ID: 7901494

Claim:
An NIR absorber consisting of a cyanine cation X + and a corresponding anion 1 / m Y m− , the cation having a general formula selected from the group consisting of (I) to (IV) where n is 1 or 2 and the radicals R 1 to R 9 have the following meanings: R 1 and R 2 , independently of one another, are a linear or branched, optionally further substituted alkyl or aralkyl radical having 1 to 20 carbon atoms, R 3 and R 4 , independently of one another, are H or CN, R 5 and R 6 , independently of one another, are one or more, identical or different substituents selected from the group consisting of —H, —F, —Cl, —Br, —I, —NO 2 , —CN, —CF 3 , —R 1 , —OR 1 , aryl- and —O-aryl, R 7 is —H, —Cl, —Br, —I, -phenyl, —O-phenyl, —S-phenyl, —N(phenyl) 2 , -pyridyl, a barbituric acid radical or a dimedone radical, it also being possible for the phenyl radicals to be further substituted, R 8 and R 9 , independently of one another, are >C(CH 3 ) 2 , —O—, —S—, >NR 1 or —CH═CH—, and the anion Y m− has the general formula [AR 10 k ] m− with a polar, ionic head group A and k nonpolar groups R 10 , k is 1, 2 or 3 and m is 1 or 2, and the nonpolar groups R 10 , independently of one another, are selected from the group consisting of linear, branched and cyclic alkyl groups having 6 to 30 carbon atoms and alkylaryl groups of the general formula -aryl-R 11 , where R 11 is a linear or branched alkyl group having 3 to 30 carbon atoms, or or the anion Y m− is a borate anion of the general formulae (V) or (VI) where R 10 is as defined above and R 12 is at least one substituent selected from the group consisting of H and linear, cyclic and branched alkyl groups having 1 to 20 carbon atoms, and in the radicals R 10 , R 11 and R 12 , even nonneighboring carbon atoms may optionally be substituted by O atoms and/or the radicals R 10 , R 11 and R 12 may be completely or partly fluorinated, with the proviso that the nonpolar character of the group is not substantially influenced thereby.