Photocrosslinkable polymers with side groups derived from indenone and the preparation and use of these polymers

A polymer, crosslinkable under the action of light, which has an average molecular weight between 1,000 and 1,000,000, as measured by the intrinsic viscosity of a solution of said polymer in N,N-dimethylformamide at 20.degree. C., and which has side groups of the formula I ##STR39## in which R.sup.3 is Cl or Br, and R, R.sup.1 and R.sup.2 are identical or different and R is a n-alkyl radical having 1 to 4 C atoms, or is H, Cl, Br or F, R.sup.1 is a n-alkyl radical having 1 to 4 C atoms, or is H, and R.sup.2 is H or CH.sub.3, or R.sup.1 and R.sup.2 together are the group --CH.sub.2 CH.sub.2 CH.sub.2 --, with the proviso that in the latter case the bond to the six-membered ring is via the C atoms in the 5-position and 6-position of the nucleus, the proportion of groups of the formula I being at least 5%, based on the number of recurring structural elements of the polymer, said polymer being a homopolymer or copolymer derived from monomers containing reactive C.dbd.C double bonds, wherein said polymer comprises

• (a) from 5 to 100 percent, based on the number of recurring structural elements in the polymer chain, or molecular chain members selected from the group consisting of formulas II to VI. ##STR40## in which the radical E has the formula I, m is a number from 2 to 6, n is a number from 1 to 10 and R.sup.6 is H or --CH.sub.3, and
• (b) from 95 to 0 percent, based on the number of recurring structural elements in the polymer chain, of structural elements of the formula IX ##STR41## in which X.sub.1 and X.sub.3 are each hydrogen, X.sub.2 is hydrogen, chlorine or methyl and X.sub.4 is hydrogen, methyl, chlorine, --CN, --COOH, phenyl, methylphenyl, methoxyphenyl, cyclohexyl, --COO--alkyl having 1-12 C atoms in the alkyl moiety, --COO--phenyl, ##STR42## --COO--alkyl--OH having 1-3 C atoms in the alkyl moiety, --OCO--alkyl having 1-4 C atoms in the alkyl, --OCO--phenyl, --CO--alkyl having 1-3 C atoms in the alkyl, alkoxy having 1-6 C atoms or phenoxy, or X.sub.1 and X.sub.2 are each hydrogen and X.sub.3 and X.sub.4 together are the grouping ##STR43## or are each --COOH or --COO--alkyl having 1-6 C atoms in the alkyl.