USPC Class Details

Description: 521 synthetic resins or natural rubbers -- part of the class 520 series / 521 synthetic resins or natural rubbers -- part of the class 520 series/() synthetic resins (class 520, subclass 1) (50) cellular products or processes of preparing a cellular product, e.g., foams, pores, channels, etc. (134) cellular product derived from two or more solid polymers or from at least one solid polymer and at least one polymer-forming system

Hierarchy/Derived subclasses

521 / 50-> 134-> 135
  -> 136
  -> 137
  -> 138
  -> 139
  -> 140

uspto searches

Patent Apps in 521/134

Granted Patents in 521/134

Use the links above or do an advanced search in ppubs for:
(521/134.ccls. or 521/135.ccls. or 521/136.ccls. or 521/137.ccls. or 521/138.ccls. or 521/139.ccls. or 521/140.ccls.)

This will show what classes derive from the input. Ex: entering 43/42.24 shows the derived classes and the search that can be used to find patents or patent applications in those subclasses.
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