Polymerisation initiators, polymerisable compositions, and uses thereof

摘要

Metal alkyl borohydrides are used as initiators of polymerisation, particularly in adhesive compositions for bonding a wide range of substrates including low surface energy substrates such as polyolefins. As described, the metal alkyl borohydrides are of the formula I wherein R<1> is C1 - C10 alkyl, R<2>, R<3> and R<4>, which may be the same or different, are H, D, C1 - C10 alkyl or C1 - C10 cycloalkyl, phenyl, or phenyl-substituted C1 - C10 alkyl or C1 - C10 cycloalkyl, provided that any two of R<1> - R<4> may optionally be part of a carbocyclic ring, and M+ is a metal ion. In particular, alkali metal trialkyl borohydrides are used, the alkali metal salt being selected from the group consisting of: Lithium triethylborohydride, Sodium triethylborohydride, Potassium triethylborohydride, Lithium tri-sec-butylborohydride, Sodium tri-sec-butylborohydride, Potassium tri-sec-butylborohydride, Lithium 9-borabicyclo Ä3.3.1Ü-nonane (9BBN) hydride, Lithium thexylborohydride, Lithium trisiamylborohydride, Potassium trisiamylborohydride and Lithium triethylborodeuteride. A polymerisable composition, particularly a two part adhesive composition. comprises: a) a free-radically polymerisable monomer component, and b) an effective amount of an initiator system for initiating polymerisation of the free-radically polymerisable monomer, said initiator system comprising a metal alkyl borohydride.