Composite structures or laminates comprising a metal (steel, tin, aluminium) or plastic (polyvinylchloride, polymethylmethacrylate, polyethylene, polystyrene, melamine- or ureaformaldehyde resin) substrate are prepared by a process comprising precoating the substrate with a solution in a halogenated aliphatic hydrocarbon solvent of resinous composition comprising a methacrylic acid, methacrylate or substituted methacrylate polymer or copolymer, a urea- or melamine-formaldehyde resin, an alkyd resin based on drying or non-drying oils or blends thereof, and then forming the polyurethane (e.g. foamed) in situ. Suitable solvents are trichloro ethylene, perchloroethylene, methylene dichloride, ethylene dichloride, chloroform, carbon tetrachloride and trichlorotrifluoromethane. The substrate which may be in the form of a sheet or box, may be degreased and roughened with abrasives before being coated with the resinous composition and heated before and after the polyurethane-forming composition is applied. The polyurethane may be prepared from polyester, polyesteramides or polyethers and organic polyisocyanates optionally in the presence of water and/or a liquid boiling below 75 DEG C. The polyesters and polyesteramides may be prepared from succinic, glutaric, adipic, suberic, acelaic, sebacic, phthalic, isophthalic and terephthalic acids, and ethylene glycol, 1,2 propylene glycol, butylene glycols, diethylene glycol, glycerol, trimethylol propane and pentaerythritol and, as necessary, ethylene diamine, hexamethylene diamine and monoethanolamine. The polyethers may be linear or branched and may be prepared from ethylene oxide, 1,2 butylene oxide, 2,3 butylene oxide, oxacyclobutane, substituted oxycylobutanes and tetrahydrofuran in the presence of a basic catalyst and water or glycerol, hexane triols, sorbitol, sucrose, pentaerythritol, triethanolamine, ethylene diamine, 2:4 and 2:6 totylene diamines, 2:4:6 tolylene triamine, 4:41-diamino diphenylmethane or triethylene tetramine. Polyisocyanates mentioned are 2:4 and 2:6 tolylene diisocyanate, hexamethylene diisocyanate, 2:4:6 toluene triisocyanate, 4:41 diisocyanato diphenylmethane and 3-methyl-4:41 diisocyanato diphenylmethane. The liquids boiling below 75 DEG C. mentioned are monofluorotrichloromethane, dibromo - difluoromethane, 1:1:2-trichloro-1:2:2-trifluoroethane, dichlorodifluoromethane and dichloromonofluoromethane. In the examples the substrate is precoated with (Examples 1, 2, 3, 4, 6 and 7) a solution of polymethacrylate copolymers in trichloroethylene and (Example 5) a solution of urea-formaldehyde and drying oil-based alkyd resins in trichloroethylene, and the polyurethane foam forming compositions are prepared from (Examples 1, 2, 3 and 5) a reaction product of 2:4, 2:6 tolylene diamines and propylene oxide, trichloromonofluoromethane, tri (b -chloroethyl) phosphate, polysiloxane-polyoxyalkylene block copolymer, dibutyltin dilaurate and diisocyanato diphenylmethane; (Example 4) as in Example 1 with glycerol present; (Example 6) a reaction product of triethanolamine and propylene oxide, water, tri -(b -chloroethyl) phosphate, triethanolamine, ethylene/propylene oxide block copolymer and diisocyanato diphenyl methane; (Example 7) as in Example 6 with trichloro monofluoromethane present.ALSO:Composite structures or laminates comprising a metal (steel, tin, aluminium) or plastic (polyvinylchloride, polymethylmethacrylate, polyethylene, polystyrene, melamine- or ureaformaldehyde resin) substrate are prepared by a process comprising precoating (brushing, spraying, dipping) the substrate with a solution in a halogenated aliphatic hydrocarbon solvent of a resinous composition comprising a methacrylic acid, methacrylate or substituted methacrylate polymer or copolymer, a urea- or melamine-formaldehyde resin, an alkyd resin based on drying or non-drying oils or blends thereof, and then forming the polyurethane in situ. Suitable solvents are trichloroethylene, perchloroethylene, methylene dichloride, ethylene dichloride, chloroform, carbon tetrachloride and trichlorotrifluoromethane. The polyurethane may be foamed, rigid, semi-rigid or flexible. The substrate which may be in the form of a sheet or box, may be degreased and roughened with abrasives before being coated with the resinous composition and heated before and after the polyurethane is applied.
展开▼
