The invention relates to the use of surface-active photoinitiators of
formula I
##STR1##
the units being arranged randomly or in blocks, and wherein n is a number
from 1 to 1000; m is a number from 0 to 100; p is a number from 0 to
10,000; x is the number 1, or, when n is 1, x may also be the number 2;
A.sub.1 and A.sub.2 are, for example, C.sub.1 -C.sub.18 alkyl; or A.sub.1
and A.sub.2 together are a single bond; R.sub.1, R.sub.2 and R.sub.3 are,
for example, each independently of the others C.sub.1 -C.sub.18 alkyl,
phenyl or C.sub.5 -C.sub.8 cycloalkyl; R.sub.4 is, for example,
unsubstituted or substituted C.sub.1 -C.sub.18 alkyl, unsubstituted or
substituted phenyl or C.sub.5 -C.sub.8 cycloalkyl; IN, when x is 1, is a
radical of formula
##STR2##
when x is 2, is a radical of formula
##STR3##
R.sub.13 and R.sub.14 are, for example, each independently of the other
C.sub.1 -C.sub.12 alkyl; Y is, for example, --(CH.sub.2).sub.a --O--; X is
OR.sub.15 or N(R.sub.16)(R.sub.17); R.sub.15 is, for example, hydrogen or
C.sub.1 -C.sub.4 alkyl; R.sub.16 and R.sub.17 are, for example, hydrogen
or C.sub.1 -C.sub.12 alkyl; X.sub.1 has, for example, one of the meanings
of X; and R.sub.18 is, for example, --(CH.sub.2).sub.a --;
in photochemically and combined photochemically and thermally crosslinkable
formulations.
