| abstract |
Quaternary boron salts are used as initiators of polymerisation in adhesive compositions for bonding low surface energy substrates such as polyolefins. The quaternary boron salts are of the formula I n n n wherein R 1 is C 1 -C 10 alkyl, n R 2 , R 3 and R 4 , which may be the same or different, are, C 1 -C 10 alkyl or C 3 -C 10 cycloalkyl, phenyl, or phenyl-substituted C 1 -C 10 alkyl or C 3 -C 10 cycloalkyl, provided that any two of R 1 -R 4 may optionally be part of a carbocyclic ring, and M + is a metal ion or a quaternary ammonium ion. n When M + is a quaternary ammonium ion, the initiator may be used in a two-part composition having a (meth)acrylate monomer in both parts and the initiator compound in one part, the two parts being in a weight ratio of about 1:1. n Particular examples of initiator compounds include sodium tetraethyl borate, lithium tetraethyl borate, lithium phenyl triethyl borate, tetramethylammonium phenyl triethyl borate, and tetra methyl ammonium phenyl tri-n-butyl borate, the last-mentioned of which is a novel compound. |