Patent ID: 6251962
Filing Date: 2001-06-26
Classification: B33Y,C08F

Abstract:
Process for the preparation ofacrylate- or methacrylate-homo- or acrylate- or methacrylate-co-oligomers with a weight average molecular weight (Mw) from 1000 to 20000,a polydispersity.ltoreq.3and a conversion of the monomers to polymers greater than or equal to 70%,characterized in thatat least one acrylic or methacrylic monomer or a mixture of said acrylic monomers with styrene or with vinylacetate, butadiene, acrylamide, acrylonitrile, vinylidene chloride or vinyl chloride is irradiated in the presence of at least one .alpha.-hydroxyketone photoinitiator or at least one phosphorus containing photoinitiator of the formula IIa or IIb ##STR5##R.sub.7 and R.sub.8 independently of one another are C.sub.1 -C.sub.18 alkyl, cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenyl, wherein the cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenyl are unsubstituted or substituted by halogen, C.sub.1 -C.sub.12 alkyl and/or C.sub.1 -C.sub.12 alkoxy, or R.sub.7 and R.sub.8 are a 5- or 6-membered S- or N-containing heterocyclic ring;R.sub.9 and R.sub.10 independently of one another are cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenyl, which residues are unsubstituted or substituted by halogen, C.sub.1 -C.sub.4 alkyl and/or C.sub.1 -C.sub.4 alkoxy, or R.sub.9 and R.sub.10 are a 5- or 6-membered S- or N-containing heterocyclic ring, or R.sub.9 and R.sub.10 together with the P-atom to which they are bonded from a ring, which contains from 4 to 10 carbon atoms and which ring may be substituted by 1 to 6 C.sub.1 -C.sub.4 alkyl radicals;or a mixture of an .alpha.-hydroxyketone photoinitiator with a phosphorus containing photoinitiator of formula IIa or IIb, said photoinitiator or photoinitiator mixture having a molar extinction coefficient .epsilon. from 0.1-2000 and at least one maximum of absorption, useful for the generation of radicals, in the range from 305 to 450 nm,at a temperature from -20 to 70.degree. C.in a solvent or solvent mixture,with light of a wavelength from 305 to 450 nm,where the concentration of the polymer in the final solution is up to 80%.