Filing in this field is concentrated: the top five assignees together hold 442 of the 1,050 records in scope, or 42.1% of the field, and the single leading assignee holds 150 records on its own — roughly three times the fifth-place count of 54. The top ten combined reach 625 records, or 59.5% of all records, after which the count per filer drops off sharply into a long tail. Anyone drafting a new claim in the core chemistry space should expect to clear prior art from this small group first.

Filings peaked at 53 in 2020 and fell to 6 by 2024, a 73% decline over the 2021-2024 span, which is the most recent period the data can treat as complete. Years after 2024 are still filling in because publication typically lags filing by around 18 months, so it would be a mistake to read the very latest years as confirming a continued fall. The honest read is that the field cooled off its 2020 peak, not that activity has stopped.

US20080012188A1, filed by BASF Corporation and published 2008-01-17, claims a one-piece vehicle insulator molded from a single homogeneous microcellular polyurethane material that nonetheless has different densities across its length — a first portion at one density and a second, more compressible portion at a lower density, joined by an intermediate section. The value of the claim sits in achieving that density gradient within a single integrally formed part rather than assembling separate density zones. Anyone designing a graded-density insulator or bumper from one polyurethane pour needs to check this claim’s scope directly.