| abstract |
Compounds of the formula I, in which n and o are a number from 0 to 50, m is a number from 1 to 50, u and v are 0 or 1, and at least one of the indices u and v is 1, R1, R2, R2a, R3 and R4 independently of one another are, for example, aromatic hydrocarbons, R5, if n and o are 0, is for example C1-C12alkyl and, if n and/or o are greater than 0, or if n and o are 0 and at the same time only one index u or v is 1, R5 may additionally, for example, be an aromatic hydrocarbon, at least one of the radicals R1, R2, R2a, R3, R4 and R5 being an aromatic hydrocarbon radical which is sterically hindered ortho to the boron atom, X is, for example, C1-C20alkylene, phenylene, biphenylene, etc., and Z is a radical which is able to form positive ions, are suitable as photoinitiators, both the compounds per se and their combination with dyes or other electron acceptors. Furthermore, the polyborane precursors of these borates possess, together with borate salts, photoinitiating properties. |