The invention relates to a process for preparing a dry film resist by
forming a photocurable resin composition onto a support film with a
thickness of 1 to 50 .mu.m and optionally laminate a protective film onto
the photocurable composition layer to obtain a dry film resist; whereby
the photocurable resin is formed from a homogeneous mixture comprising
(a) from 20 90 wt % of an alkaline soluble binder oligomer or polymer;
(b) from 5 to 60 wt % of one or more photopolymerizable monomers which
are compatible with the oligomers and polymers of component (a); (c) from
0.01 to 20% by weight of one or more photoinitiators; (d) from 0 to 20%
by weight of additives and/or assistants; and (e) from 0.1 to 10% by
weight of a leuco triphenylmethane dye of the formula (I), wherein
R.sup.1 is a residue selected from (II), R.sup.2 is C.sub.1 C.sub.12
alkyl or phenyl which may be mono-, di- or tri-substituted by C.sub.1
C.sub.6 alkyl, trifluoromethyl, C.sub.1-6 alkoxy, C.sub.1-6 alkylthio,
halogen and nitro; R.sup.3 is hydrogen or C.sub.1 C.sub.12 alkyl; R.sup.4
to R.sup.9 independently of one another are hydrogen or C.sub.1 C.sub.12
alkyl; X is O, S, NH or N--C.sub.1 C.sub.12-alkyl; (a) to (e) being 100%
by weight. The above composition is useful to avoid unfavourable colour
generation during the heat lamination ##STR00001##