Cross-linkable structurally colored polymers, their preparation and their use in compositions for coatings

A structurally colored polymer having a number-average molecular weight between 1000 and 12,880 g and carrying m hydroxy functions and n groups of the formula:

• ##STR23## in which X.sub.1 is a member selected from hydrogen and methyl, R.sub.1 and R.sub.2 are the same or different and represent a member selected from hydrogen and methyl, m is a number from 0 to 49 and n is a number from 2 to 70 such that the sum m+n is from 7 to 70 and the ratio m/n is from 0 to 2.4, said polymer being obtained by:
• (a) first preparing a structurally colored oligomer containing m+n hydroxy functions, m and n being as defined above, by free radical polymerization of one or more monomers of the formula:
• ##STR24## in which X.sub.2 is a member selected from hydrogen and methyl, R.sub.4 and R.sub.5 are the same or different and represent a member selected from hydrogen and methyl, R.sub.3 is an aliphatic linear or branched hydrocarbon containing from 2 to 7 carbon atoms or said hydrocarbon substituted by chlorine, and p is equal to 1 or 2, in the presence of one or more dyestuffs containing one or two groups of the formula:
• ##STR25## in which X.sub.1 is as defined above, and R.sub.6 and R.sub.7 are the same or different and represent a member selected from hydrogen and methyl, and containing no group reactive towards hydroxy functions, and
• (b) converting n hydroxy functions of the oligomer prepared in (a) into groups of the formula:
• ##STR26## by reaction of the said oligomer with a compound of the formula:
• ##STR27## in which Y is a member selected from chlorine and bromine, and X.sub.1, R.sub.1, R.sub.2 have the same definition as above, in the absence of dyestuff, the amount of compound of formula (II) introduced being calculated to act on n of the hydroxy functions of the oligomer formed in (a), the total amount of dyestuff used representing 0.5% to 20% by weight of the whole of the compounds used.