US PATENT SUBCLASS 528 / 296
.~.~.~ Reactant contains three or more carboxylic acid groups or is derivative thereof

Current as of: June, 1999
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528 /   HD   SYNTHETIC RESINS OR NATURAL RUBBERS -- PART OF THE CLASS 520 SERIES

*  DD  SYNTHETIC RESINS (Class 520, Subclass 1) {23}
271  DF  .~ FROM CARBOXYLIC ACID OR DERIVATIVE THEREOF {10}
272  DF  .~.~ From di- or higher ester of a polycarboxylic acid as sole reactant, or from a polycarboxylic acid or derivative with a compound containing two or more hydroxyl groups or salts thereof {15}
296.~.~.~ Reactant contains three or more carboxylic acid groups or is derivative thereof

DEFINITION

Classification: 528/296

(under subclass 272) Subject matter wherein at least one reactant is present which contains three or more carboxylic acid groups, or wherein a reactant is present which contains three or more carboxylic acid derivative groups, or mixtures thereof (e.g., trimellitic acid, pyromellitic tetracarboxylic acid dianhydride, etc.).

(1) Note. For purposes of this subclass an anhydride having the general formula, which may be linear or cyclic is considered as being a polycarboxylic acid. A compound having both an anhydride and a free carboxylic acid is considered as being a tricarboxylic acid, e.g., as shown below in the first illustration, and a compound containing two anhydride groups is considered as being a tetracarboxylic acid, e.g., as shown

below in the second illustration. [figure] [figure]