| 摘要 |
A sheet registration device including a hub having an axis of rotation and a plurality of resilient plastic blades arranged in radial planes passing through said axis and extending in the direction of said axis beyond one end of the hub towards sheet-engaging tips lying in a common plane normal to said axis said blade being made of a polyurethane elastomer obtained by the reaction of a polytetramethylene ether glycol having the formula HO[(CH2)4O]nH where n is from 8 to 41, preferably 39 to 41, and from about 20 to about 95 parts preferably 22 to 26 parts by weight per 100 parts by weight of said glycol of a diisocyanate selected from the group consisting of diphenylmethane diisocyanates, toluene diisocyanates, naphthalene diisocyanates and blends thereof and a sufficient amount of cross linking agents to provide a crosslinked elastomer, said cross linking agents comprising a mixture of from about 75% to 60% by weight of a diol having the formula: HO(R1) OH where R1 is a straight or branched chain alkyl group having from 2 to 12 carbon atoms and from about 25% to 40% by weight of a triol having the formula: R'-C-[(OH)a(CH2OH)b] where R' is H,CH3or C2H5,a is 0 or 1, b is 2 or 3 and a+b=3.
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