521 / | HD | SYNTHETIC RESINS OR NATURAL RUBBERS -- PART OF THE CLASS 520 SERIES |
* | DD | SYNTHETIC RESINS (Class 520, Subclass 1) {3} |
50 | DF | .~ CELLULAR PRODUCTS OR PROCESSES OF PREPARING A CELLULAR PRODUCT, E.G., FOAMS, PORES, CHANNELS, ETC. {27} |
134 | DF | .~.~ Cellular product derived from two or more solid polymers or from at least one solid polymer and at least one polymer-forming system {6} |
137 | .~.~.~ At least one polymer is derived from a -N=C=X reactant wherein X is a chalcogen atom or wherein the polymer-forming system contains the same type of reactant |