| 摘要 |
An impervious sheet material is produced by impregnating a material having a permeability value of 5,000-25,000 gm/hr/ 100 sq m with a linear polymer derived from a high mol wt polyglycol having a mol wt of 750-10,000, a diisocyanate, and a diamine, the ratio of diisocyanate to polyglycol being 2.5 to 1 and the ratio of diamine to diisocyanate being 1 to 1. The permeable material is produced by impregnating a shrunk polyethylene terephthalate felt with a polymer as disclosed in United States Patent No. 2,723,935; 3,067,482; or 3,067,483. A low mol wt polyglycol having a mol wt of less than 750 may be mixed with the high mol wt polyglycol, the ratio of low to high mol wt polyglycol being 0.5-3. The linear polymer may be formed in situ by reaction of the diamine with a polyglycol-diisocyanate prepolymer temporarily stabilized with a vaporizable ketoxime. The high mol wt polyglycol may be polyethylene, propylene, tetramethylene, hexamethylene, octamethylene, nonamethylene, decamethylene, or dodecamethylene glycol. The low mol wt polyglycol may be a polymer of ethylene, diethylene or dipropylene glycol; 1,2- or 1,3- propanediol; 1,2-, 1,3- or 1,4-butanediol; 1,5-pentanediol; 1,10-decanediol; 1,1-cyclohexanedimethanol; 3-cyclohexene-1, 1-dimethanol; 2-hydroxyethoxy -1-propanol; or 2,2/sv-(thiobis(ethyleneoxy)) diethanol. The diisocyanate may be 2,4-tolylene, 2,6-tolylene, m-phenylene, 4,4/sv-biphenylene, 4-chloro-1,3-phenylene, 1,5-naphthalene, 1,4-tetramethylene, 1,6-hexamethylene, 1,10-decamethylene, 1,4-cyclohexylene, or tetrahydronaphthalene diisocyanate; or methylene bis(4-phenyl or cyclohexyl isocyanate). The diamine may be m-phenylene, 2,4-tolylene, ethylene, 1,3-propane, 1,4-butane, 1,5-pentane, or 1,6-hexane diamine; 4,4/sv-methylene dianiline; or hydrazine. Impregnation of the permeable material is effected by a suitable method under vacuum or pressure. Curing is effected by heating the impregnated material. |
