IMPROVEMENTS IN POLYUREAURETHANE SHOCK ABSORBING UNITS AND METHOD FOR PREPARING THE SAME.

摘要

WE CLAIM: 1. A shock absorbing unit suitable for use In a railroad draft gear comprising a shock absorbing element characterized by a shaped solid resilient polyureaurethane composition having two opposing and substantially parallel force-receiving surfaces connected by at least one sidewall and having metal force-receiving plates adhered to its force-receiving surfaces where said unit is characterized by being prepared by the method which comprises applying a polyureaurethane reaction mixture into a mold of required con- figuration and having metal force-receiving plates inserted therein followed by curing said reaction mixture, said reaction mixture being at least one diamine selected from the group consisting of orthodichlorobenzidene and  4,4"-methylene  bisorthochloroaniline with the reaction product of 3,3"-bitolylene-4s4"-diiso-cyanate and reactive hydrogen containing  polymeric materials selected from  (1) polytetramethylene ether glycols having an average molecular weight in the range of from about 800 to about 2200 with a total average molecular weight in the range of about 1200 to about 1500 or (2) a mixture of reactive hydrogen-containing materials comprising in the range of from about 30 to about 100 weight percent polytetramethylene ether glycols having an average molecular weight of from about 800 to about 2200 and correspondingly in the range of up to about 70 weight percent of polyester polyols having a molecular weight in the range of from about 800 to about 2200 selected from at least one of (a) caprolactone polyesters prepared from caprolactones containing 6 to 10 carbon atoms and glycols containing 2 to 10 carbon atoms, (b) adipates of adipic acid and glycols containing 2 to 7 carbon atoms and (c) azelates of azelaic acid and glycols containing 2 to 7 carbon atoms, with the requirement that the total average molecular weight of the mixture of polytetramethylene ether glycol and polyester polyol is in the range of about 1300 to about 1900, where the ratio of isocyanate groups of the diisocyanate to the sum of hydroxyl groups of the polyols is from about 1.7 to about 2.5, where the ratio of primary amino groups of the diamine to excess isocyanate groups over the sum of hydroxyl groups of the polyols is hi the range of about 0.6 to about 1 and where the acid number of the polyols is less than about 1, and where said polyureaurethane composition is further characterized by a -40C cold temperature compression test where the said composition, at -40C., when shaped and cured to a solid circular disc with a straight side-wall, having a diameter of about 1.13 inch and a thickness of about 0,5 inch requires a maximum pressure of 7500 pounds per square inch applied to its flat surfaces to compress the disc 40 percent.