The ranking covers 95 companies across 366 records, with a clear leader holding 38 records versus 18 at fifth place and 11 at tenth. The top 5 assignees together account for 39.1% of all records and the top 10 for 57.1%, so the field has a defined leadership group but is not dominated by a single company. The remaining 85 companies in the ranking hold the balance, typically with small individual filing counts, which is where niche or newer entrants tend to sit.

No, filing activity has declined since its peak. Filings rose from 8 in 2017 to a peak of 32 in 2018, then fell steadily; from 2021 to 2024, filings dropped 83%, from 6 records to 1. Because publication lags filing by roughly 18 months, the 2025 and 2026 figures are still incomplete and should not be read as confirming a further decline, but the multi-year trend through 2024 is clear.

US6846859B2 claims a polyolefin composition combining a primary phenolic antioxidant for long-term thermal stability with a phosphite processing stabilizer for melt-processing stability, plus a distinct sacrificial phosphite antioxidant added specifically to reduce yellowness index. The key limitation is that the sacrificial phosphite and the processing-stabilizer phosphite must be different compounds performing separate roles. A formulation that uses a single phosphite compound for both jobs, or that addresses yellowing through a non-phosphite route, sits outside this specific claim structure, though it should still be checked against the broader stabiliser art.

The technology composition data shows additive-use claims (C08K, 70.8% of records) far outweighing base polymer-composition claims (C08L, 42.9%), which suggests most competitive activity is in how additives are dosed and combined rather than in new resin chemistries. Specific failure modes named in the underlying search — hydrolytic stability, blooming resistance and colour retention across multiple extrusion passes — appear less densely covered on their own than the broad additive-use category. Fibre-grade applications, reflected in the smaller D01F share (7.1%), are another area worth checking directly rather than assuming coverage from the general polyolefin art.

C08K (use of additives in polymers) and C08L (polymer compositions) are the two dominant classes, covering 70.8% and 42.9% of the 366 records respectively. Secondary classes worth including in a search are C08G condensation polymers (11.7%), C08J polymer processing and solutions (9.3%), and C07C and C07F for the underlying antioxidant and phosphite chemistries (6.6% and 4.6%). Because a single record can carry several of these classes, a search limited to just one will miss a meaningful share of relevant prior art.