Patent GB-1469643-A (GB)
Title: Photopolymerisable composition
IPC: C08F2/00
Filed: 1973-11-19
Abstract: 1469643 Photopoloymerizable composition IMPERIAL CHEMICAL INDUSTRIES Ltd 21 Nov 1974 [19 Nov 1973] 53581/73 Heading C3P A photopolymerizable composition comprises at least one polymerizable ethylenically unsaturated material and a photosensitive catalyst comprising (a) at least one photosensitizer having the structure where R and R 1  may be the same or different and each is a hydrocarbyl group or a substituted hydrocarbyl group or R and R 1  together may form a fused aromatic ring system and A is a hydrocarbyl group or a substituted hydrocarbyl group or a group of formula wherein X and Y each is hydrogen or a hydrocarbyl or substituted hydrocarbyl group, or X and R together may form a hydrocarbyl or substituted hydrocarbyl group R<SP>1</SP> and Y and R 1  together may form a hydrocarbyl or substituted hydrocarbyl group R<SP>1</SP> 1 , and (b) at least one reducing agent capable of reducing the photosensitizer when the photosensitizer is in an excited state. The photosensitizer preferably has the structure e.g. N,N<SP>1</SP>-oxalyl indigo where R<SP>1</SP> and R<SP>1</SP> 1  are both phenylene. The reducing agent may have the structure R 2 R 3 R 4 M where M is an element of Group VB of the Periodic Table and R 2 , R 3 , R 4 , which may be the same or different, are hydrogen, hydrocarbyl or substituted hydrocarbyl or groups in which two units from R 2 , R 3  and R 4  together with M form a cyclic ring, no more than two of R 2 , R 3  and R 4  being hydrogen, and where M is attached directly to an aromatic group R 2  at least one of R 3  and M 4  has a HC# group attached to M. Numerous examples of primary, secondary or tertiary amines are given besides dialkylaminoalkanols, diamines, piperidine, triallylamine, allyl thiourea, o-tolyl thiourea, s-benzyl isothiuronium p-toluene sulphinate, sodium diethyl dithiophosphate, and iodol-3-acetic acid. The specific examples use dimethylaminoethyl methacrylate as the reducing agent. The ethylenically unsaturated material may be one or more monomers selected from vinyl monomers, allyl monomers and vinylidene monomers of which numerous examples are given. The ethylenically unsaturated material may include at least one ethylenically unsaturated polymer, e.g. an ethyleneically unsaturated polyester, suitably in combination with at least one ethylenically unsaturated monomer which may be or include divinyl benzene, glycol dimethacrylate or a reaction product of a hydroxyalkyl acrylate or methacrylate with an isocyanate-ended adduct of a diol and a diisocyanate. The photopolymerisable composition may be irradiated with visible light or ultraviolet radiation, e.g. radiation having a wavelength of 230-600 mÁ. In the specific examples polymeric material is prepared by irradiating compositions comprising: unsaturated polyester resin containing styrene, N,N<SP>1</SP>-oxalyl indigo and dimethylaminoethyl methacrylate (1); hydroxymethyl methacrylate, N,N<SP>1</SP>-oxalyl indigo and dimethylaminoethyl methacrylate (2) (3); hydroxyethyl methacrylate, 2,3-dibenzoylnorborn-2-ene and dimethylaminoethylmethacrylate (4); and an unsaturated polyester resin containing styrene, dimethylaminoethyl methacrylate and a mixture of the two isomers below obtained by bromination of of 2,3,-dibenzoylnorborna-2,5-diene (5).