Patent GB-1444961-A (GB)
Title: Thermosetting polymer dispersions and process for production thereof
IPC: C08G18/00
Filed: 1973-07-02
Abstract: 1444961 Thermosetting polymer coatings DAI NIPPON TORYO CO Ltd 2 July 1973 [3 July 1972] 31504/73 Heading B2E [Also in Division C3] Thermosetting polymer dispersions comprise an organic liquid dispersion medium having stably dispersed therein particles of a copolymer formed from ethylenically unsaturated monomers, the organic liquid being incapable of dissolving the copolymer 'but being capable of dissolving the monomers from which it is formed, said particles having around their periphery a protective layer of a stabiliser which (a) has a component compatible with the copolymer or chemically bonded thereto and (b) is solvated in the organic liquid, the stabiliser having been prepared by (A) selecting (1) a partially blocked isocyanate compound containing at least one free isocyanate group and at least one blocked isocyanate group and (2) an active hydrogen-containing polymer, the sum of the number of free and blocked isocyanate groups in one molecule of the isocyanate compound and the number of active hydrogen groups in one molecule of the polymer being at least 5, and (B) reacting compounds (1) and (2) in such a ratio that the amount of active hydrogen groups is in excess, on an equivalents basis, with respect to the amount of free isocyanate groups. The stabiliser may be formed by reacting a blocked isocyanate as defined above with a resin containing active hydrogen atoms and selected from alkyd resins, epoxy ester resins, epoxy-modified alkyd resins, urethanated oil resins and maleic oil resins, each being modified by an unsaturated fatty acid-containing oil; or with a vinyl polymer containing active hydrogen atoms. In an embodiment, the copolymer may also contain active hydrogen atoms and, in this case, compounds (1) and (2) are reacted in such a ratio that the amount of active hydrogen groups in polymer (2) is at least equivalent to 'the amount of free isocyanate groups. The dispersions are obtained by copolymerising ethylenically unsaturated monomers in the organic liquid referred to above and in the presence of the stabiliser defined above. The dispersions may optionally include such additives as pigments dissociation catalysts levelling agents, driers and extenders. In Examples the dispersed copolymer particles are derived from the following monomers (1) and (5) methyl methacrylate, acrylonitrile and styrene, (2) methyl methacrylate, acrylonitrile, 2-hydroxyethyl methacrylate and styrene, (3) methyl methacrylate, acrylonitrile, styrene and n-butyl methacrylate, (4) methyl methacrylate, acrylonitrile, styrene, n-butyl methacrylate and N- butoxymethyl-acrylamide (6) methyl methacrylate, acrylonitrile, N-methylolacrylamide and styrene, (7) methyl methacrylate, acrylonitrile and n-butyl acrylate, (8) methyl methacrylate, 2-hydroxyethyl methacrylate and styrene, (9) methyl methacrylate, acrylonitrile and n-butyl methacrylate, and (10) methyl methacrylate, styrene and ethyl acrylate. The Examples also illustrate the preparation of the stabilisers which are derived from mono-blocked W, W'- diisocyanato-dimethylbenzene, toluene diisocyanate, hexamethylene diisocyanate, 4, 4'- methylene-bis-(cyclohexyl isocyanate), isophorone diisocyanate or lysine diisocyanate methyl ester, and from oil-modified alkyd, epoxy or urethanated resins. The compositions may be applied to substrates such as iron, aluminium, zinc, zinc-plated steel, plywood, wooden board, paper, cloth, fabrics and plastics.