Compositions with organohalogen compound and diazonium salts as photoinitiators of epoxy compounds in photo-polymerization

DETAILED DESCRIPTION OF THE INVENTION Thus, in accordance with the procedure of this invention, a mixture is formed of an epoxide material in admixture with a latent catalyst precursor selected from the group consisting of (1) an organohalogen compound or (2) a synergistic mixture of an organohalogen with an aryl diazonium salt of a complex halogenide or, alternatively, a halogenated epoxide material in the absence of the latent catalyst precursor.
The composition at a convenient time subsequently is exposed to electromagnetic radiation or other energy sources to release an active catalyst or catalysts which effects the polymerization of the epoxide material.
In some instances, the composition is heated following exposure.
The Organohalogens Any organic halogen compound that decomposes under the action of suitable energy sources for example, electromagnetic radiation, to release an active catalyst effective to initiate polymerization of the epoxide material, and in which the halogen is of an atomic number of 9-53, e.
g.
, fluorine, chlorine, bromine, and iodine, may be employed herein.
The organohalogen is believed to decompose under the action of such energy to liberate halogen atoms as shown in equation 1, utilizing carbon tetrabromide, for example: CBr.
sub.
4.
sup.
hv.
CBr.
sub.
3 + .
Br (1) The halogen is then believed to initiate polymerization of the epoxide by either or several of: (A) Abstracting a hydrogen atom from a solvent or the monomer to form an acid (HX) or (B) Reacting with a metal, for example, a metal substrate to which the composition is applied, to form a Lewis acid halide or (C) Acting as a Lewis acid by itself to initiate polymerization.
Preferably, the compound will exhibit bond dissociation energies for the carbon to halogen bond of between about 40 and 70 kilogram calories per mole or less and especially 60 kilogram calories per mole or less.
In general, organic bromides and iodides require less energy to dissociate, provide stronger acids upon dissociation, and are preferred herein for these reasons