Patent GB-1498408-A (GB)
Title: Coating compositions
IPC: C08G18/70
Filed: 1975-06-13
Abstract: 1498408 Coating compositions IMPERIAL CHEMICAL INDUSTRIES Ltd 13 June 1975 [14 June 1974] 26459/74 Heading C3R A coating composition comprises a blend of (1) a dispersion in an organic liquid comprising a major proportion of aliphatic hydrocarbon of particles of a polyisocyanate insoluble in the organic liquid, the dispersion being stabilized by a polymeric stabilizer at least one component of which is soluble in the organic liquid and at least one other component of which is soluble in the disperse particles of polyisocyanate, each component having a molecular weight of at least 500, and the ratio of the total molecular weights of the individual components of the two types being from 3 : 1 to 1 : 3, and (2) a solution in a solvent comprising a major proportion of aliphatic hydrocarbon of a material containing groups which are reactive with the NCO groups contained in or yielded by the polyisocyanate of dispersion (1). The aliphatic hydrocarbon may be linear or branched and has a B.Pt. in the range 70-220‹ C.; e.g. white spirit. The amount of stabilizer in the dispersion is usually 1-10% wt. based on the weight of the disperse phase, and the particle size of the dispersion is usually 10-0À1 Á. The composition may also comprise a catalyst, pigment, filler, thicker and additional organic liquids. The disperse particles of polyisocyanate may be liquid or solid at ambient temperatures. The polyisocyanate is preferably in the form of a prepolymer. The stabilizer is preferably a block or graft copolymer and the component thereof soluble in the disperse particles of polyisocyanate preferably comprises an isocyanate or polyisocyanate containing moiety, and is preferably a polyisocyanate prepolymer and the component thereof soluble in the continuous phase is preferably aliphatic in character, particularly a poly- (hydroxyalkanoic acid). Other suitable coinponents soluble in the continuous phase include poly(C 10 -C 18  alkyl-methacrylates), poly(tertiary-butylstyrene) and OH-terminated polybutadiene. The components of the two types in the polymeric stabilizer may be linked by a condensation reaction. The NCO-reactive group containing material may contain OH, amino, carboxyl and mercapto groups, e.g. polyamines, amine - terminated polyamides, polyureas, saturated polyhydric alcohols, polyhydroxylgroup containing linear polyesters and alkyd resins. In the examples coating compositions are prepared comprising a blend of (1) a dispersion in an aliphatic hydrocarbon solvent (boiling range 150-200‹ C). of a polyisocyanate prepolymer prepared either by reacting 3 moles of hexamethylenediisocyanate and 1 mole of water (prepolymer A) or by reacting 3 moles of toluene diisocyanate and 1 mole of trimethylol propane (prepolymer B), and a polymeric stabilizer prepared by first reacting poly(12- hydroxystearic acid) with the glycidyl ester of a tertiary C 8 -C 10  aliphatic acid in the presence of a (C 12 -C 14  alkyl) dimethylamine and then with polyisocyanate prepolymer (A) in the presence of dibutyltin dilaurate, and (2) a solution in an aliphatic hydrocarbon solvent of an alkyd resin prepared from coconut oil, pentaerythritol and phthalic anhydride; and optionally (3) dibutyl tin dilaurate and/or rutile titanium dioxide and white spirit. The coatings are applied to substrates and dried at room temperature.