GB1117983A - Process for improving the mechanical properties of elastic polyurethane filaments - Google Patents

Abstract

Polyurethane spinning solutions, suitable for the production of elastomeric filaments by dry spinning, are made as follows. In Example 1, 6000 parts of a polyester of adipic acid, hexane 1,6 - diol and 2,2 - dimethyl propane - 1,3 - diol (molar ratio of diols 65:35) of OH number 61.4 are heated with 1354 parts of 4,41-diphenylmethane diisocyanate and 1864 parts of chlorobenzene for one hour at 100 DEG C. and the NCO preadduct solution formed is cooled to room temperature. 8520 parts of the above preadduct solution are introduced into a 70 DEG C. hot solution of 182.5 parts of carbohydrazide in 17942 parts of dimethyl formamide, pigmented with 800 parts of a 33% titanium dioxidedimethyl formamide paste, and, when cooled to room temperature, treated with 18 parts of hexane-1,6-diisocyanate. The elastomer solution so made has a viscosity of 750 poises at 20 DEG C. In Example 2, 800 parts of a polyester similar to that of Example 1 but having an OH number of 67.1 are heated with 222 parts of 4,41-diphenylmethane diisocyanate and 258 parts of chlorobenzene for 80 minutes at 95 to 98 DEG C. and the NCO preadduct solution obtained is then cooled to room temperature. 19.65 parts of ethylene diamine and 2.68 parts of 1,3-propylene diamine are dissolved in 2376 parts of dimethyl formamide and treated with about 30 parts of solid carbon dioxide. 1100 parts of the above NCO preadduct solution are introduced into the suspension of aminocarbonates formed. A highly viscous elastomer solution results with evolution of carbon dioxide. After pigmentation with 90 parts of 33% titanium dioxide-dimethyl formamide paste, this elastomer solution has a viscosity of 520 poises at 20 DEG C.