Appeal No. 96-2708
Application 08/335,432
claims. Note in particular that in Example 4 (page 2) Perry describes blending tolylene
2:4 and 2:6-diisocyanate with zinc carboxylates (component Aa), lead acetate (component
Ab), dimethylbenzylamine and 4-dimethylaminopyridine (components Ac), a polyol having
a molecular weight of 6000 (component B) and castor oil fatty acid (component D). While
Perry teaches the use of polyols and mixtures of polyols having a molecular weight
between 200-6000, he does not specifically disclose the use of a low molecular weight(62-
399) with the higher molecular (400-10,000) polyol in combination. Perry also does not
teach the use of RIM. However, Sweeney teaches that diol chain extenders, such as 1,4-
butanediol, when added to polyol/diisocyanate constituents result in a molded product that
is stiffer and harder (pages 54-55). In addition, Sweeney teaches that RIM enables better
mixing of the composition over hand mixing (Page 69, Table 3-6) Accordingly, one of
ordinary skill in the art would have found it prima facie obvious to employ a low molecular
weight diol chain extender in polyol/diisocyanate systems, especially in view of Perry’s
teachings to employ mixtures of polyols of a molecular weight range that encompasses
that claimed, with the reasonable expectation that the molded product would be stiffer and
harder. In
addition, one of ordinary skill in this art would have found it obvious to do mechanically
(RIM) what was previously done by hand(stirring). In re Venner, 262 F.2d 91, 95, 120
USPQ 192, 194 (CCPA 1958).
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