| 摘要 |
Polyureas are prepared by contacting with water a composition comprising (a) an aromatic polyisocyanate which is the phosgenation product of a polyamine and has not been distilled, and (b) a supersolvent. The polyisocyanate is preferably 2,4- and/or 2,6-tolylene diisocyanate or 4,41-diisocyanatodiphenylmethane, but a number of amines giving rise to other isocyanates are also listed. Examples of supersolvents are dimethyl-formamide and -acetamide, N-methylpyrrolidone, tetramethylurea, N-ethyltoluenesulphonamide, dimethyl sulphone and dimethyl sulphoxide. Minor amounts of active H compounds such as polyols and polyamines may be used additionally. The process may be used to form cellular products (see Example 4). The polymers formed in situ from these compositions are used for binding wood chips, ground leather or ground cork into sheet or moulded forms.ALSO:In Example 7 an abrasive paper is prepared by painting a mixture of 4,41-diisocyanatodiphenylmethane and dimethylformamide on sized paper and immediately sprinkling on 100 mesh carborundum.ALSO:A composition comprises (a) an aromatic polyisocyanate which is the phosgenation product of a polyamine and has not been distilled, and (b) a supersolvent other than a sulphone. Specified polyamines to be phosgenated are tolylene and phenylene diamines, s-triaminobenzene, 2,4,6-triaminotoluene, benzidine, 3,31-dimethylbenzidine; 4,41-diaminodiphenylmethane, its 3,31-dimethyl and -dimethoxy derivatives and 4,41,411 - triaminotriphenylmethane; 4,41 - diaminodiphenyl - ether, -sulphone and -sulphide, and 2,4,41 - triaminodiphenyl ether; 1,4- and 1,5-naphthylenediamines, 2,5-diaminofluorene and 1,3,5-triaminonaphthalene. Examples of supersolvents are dimethyl-formamide and -acetamide, N - methylpyrrolidone, tetramethylurea, N-ethyltoluenesulphonamide and dimethyl sulphoxide.ALSO:A paper, leather, metal, or wood substrate is coated by spraying, dipping or roll with a polyurea film by application of a composition comprising (a) an aromatic polyisocyanate (e.g. tolylene diisocyanate or 4, 4/sv-diisocyanatodiphenylmethane) which is the phosgenation product of a polyamine and has not been distilled, and (b) a supersolvent, e.g. dimethyl-formamide, dimethylacetamide, N-methylpyrrolidiene, tetramethylurea, N-ethyltouenesulphonamide dimethyl sulphone or dimethyl sulphoxide, the polyurea being formed by reaction of the isocyanate with water in the substrate or in the atmosphere.ALSO:Fibrous material, such as cloth, paper, board, and paper pulp is impregnated with a polyurea which is formed in situ by reaction with water of a composition comprising (a) an aromatic polyisocyanate (e.g. tolyene diisocyanate or 4, 4/svdiisocyanatodiphenylmethane) which is the phosgenation product of a polyamine and has not been distilled, and (b) a supersolvent, e.g. dimethylformamide, dimethylacetamide, N-methylpyrrolidone, tetramethylurea, N - ethyltoluenesulphonamide, dimethyl sulphone or dimethyl sulphoxide. The compositions may be used to treat fabrics, paper and boards derived from asbestos, cotton, kraft pulp, flax, nylon, poly (ethylene tetraphthalate) and polyacrylonitrile and to seal wood and porous masonry. |
