US PATENT SUBCLASS 528 / 298
.~.~.~ Fused- or bridged-ring-containing reactant other than solely as cyclic acid anhydride group

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}
298.~.~.~ Fused- or bridged-ring-containing reactant other than solely as cyclic acid anhydride group

DEFINITION

Classification: 528/298

(under subclass 272) Subject matter wherein at least one reactant contains a fused or bridged ring with the proviso that the cyclic anhydride group is not the sole group fused or bridged to another ring.

(1) Note. A bridged or fused ring system for purposes of this subclass requires that a given ring system be attached at two different nuclear atoms of its ring system to an atom or chain of atoms which, when taken together with the two nuclear atoms, forms an additional ring structure.

SEE OR SEARCH THIS CLASS, SUBCLASS:

308+, for phthalic acid anhydride as a reactant.