Patent GB-1239701-A (GB)
Inventor: HUTCHINSON F G
IPC: B29B7/00
Filed: 1969-01-27
Abstract: 1,239,701. Articles and compositions based on polyurethanes an vinyl compounds. IMPERIAL CHEMICAL INDUSTRIES Ltd. 8 Jan., 1970 [27 Jan., 1969], No. 4446/69. Headings C3C, C3P and C3R. Novel compositions comprising homogeneous mixtures of cross-linked polyurethanes and vinyl monomers or polymers, and shaped polymeric articles are obtained by gel-polymerizing a homogeneous composition comprising at least one vinyl monomer and the precursors of a cross-linked polyurethane and shaping the composition at a stage when it is still fluid, the said starting composition comprising from 5% to 95% by weight of cross-linked polyurethane precursors free of groups copolymerizable with vinyl monomer and from 95 to 5% by weight 'of at least one vinyl monomer, the gelation of the polyurethane being substantially completed 'before polymerization of the vinyl monomer is allowed to proceed to the extent that the vinyl polymer so produced forms a separate phase, and the polymerization of the vinyl monomer being thereafter completed. Thin sections of the product examined by electron microscopy 'reveal domains of vinyl polymer having dimensions not greater than 10Á separated by poly- 'urethane regions having dimensions not greater than 1000A, these domains having continuity through the body of the material. The crosslinked polyurethane precursors may comprise an isocyanate-terminated prepolymer and at least one other component capable of cross-linking the prepolymer. If desired, this prepolymer may be formed before admixture with the vinyl monomer. As an alternative, the precursors of the cross-linked polyurethane may be gelled alone or in admixture with at least one vinyl monomer, and during but before completion of such gelation adding at least one vinyl monomer or further increments of at least one vinyl monomer. The vinyl monomer may be mono- or poly-functional or a mixture thereof. It may be used in presence of polymerization inhibitors or catalysts. The components of the starting composition are preferably chosen so that polyurethane gelation occurs at a relatively low temperature, while vinyl polymerization may be subsequently effected at a higher temperature. The products may be cast into clear colourless sheets or may be reinforced with fillers such as chopped strand fibre glass matt. Articles having simple profiles may be heatsoftened and further shaped. Alternatively, the cross-linked polyurethane component may be foamed during gelation using, e.g., water and surfactants. In examples, the cross-linked polyurethane component is obtained from hexamethylene, isophorone, diphenylmethane, 2: 4- toluene and 2: 6-toluene, diisocyanates; polypropylene glycol, oxypropylated trimethylol propane, poly(ethylene adipate), pentaerythritol - modified poly(oxyethylene adipate) and a condensate of trimethylol propane, 1,2- propylene glycol and sebacic acid; butane-1,4- diol, diethylene glycol, trimethylol propane and butane-1,4-diamine; water; surfactants; dibutyl tin dilaurate and benzoyl chloride. The vinyl monomer is exemplified by methyl methacrylate, glycol dimethacrylate, acrylonitrile, styrene, nonyl methacrylate and vinyl chloride, used in admixture with azobisisobutyronitrile, quinol, 2,4-dihydroxybenzophenone, benzoyl peroxide and conventional amine catalyst.