Ultraviolet crosslinkable copolymers

摘要

Preparation of crosslinked pressure-sensitive adhesives comprises two-stage or multi-stage free-radical addition polymerization of at least two copolymerizable monomers in the presence of a polyvalent mercaptan(s), producing block copolymers containing a polyvalent thioether unit(s); coating of the polymer from the melt on a backing; and crosslinking of the polymer on the backing by irradiation with ultraviolet radiation. - Preparation of crosslinked pressure-sensitive adhesives partly based on block copolymers comprising a polyvalent thioether unit(s), comprises: - (1) two-stage or multi-stage free-radical addition polymerization of at least two copolymerizable monomers in the presence of a polyvalent mercaptan(s), monomer(s) comprising a functional group which on irradiation with ultraviolet rays initiates a UV crosslinking, the polymerization producing block copolymers containing a polyvalent thioether unit(s); - (2) coating of the polymer from the melt on a backing; and - (3) crosslinking of the polymer on the backing by irradiation with ultraviolet radiation. - An INDEPENDENT CLAIM is also included for block copolymers obtained by two-stage or multi-stage free-radical addition polymerization of at least two copolymerizable monomers in the presence of a polyvalent mercaptan(s). The block copolymers are of formula (R1,iP1,iS)mX(SP2,jR2,j)m. - i = 1 to n; - j = 1 to m; - n, m = integers; - P1,i = polymer segments from a monomer group comprising first monomers A and/or copolymer segments from a monomer group comprising first monomers A and third monomers C, where the I segments P1 can have different lengths and different chemical compositions; - P2,j = polymer segments from a monomer group comprising second monomers B and/or copolymer segments from a monomer group comprising second monomers B and third monomers C, where the j segments P2 can have different chemical compositions; - R1,I, R2,j = radicals capping the segments P1,i and P2,j; - X = linking unit, with X(S)n+m=polyvalent thioether unit, the valency being at least n+m. - At least one of the segments P1,i and/or P2,i contains copolymerized monomers C. The monomers C contain the functional groups which on irradiation with UV rays initiate a UV crosslinking.