This landscape tracks 1,115 patent families published between 2015 and the 2026 data cut-off, built from a search combining polyimide and polyimide film terminology with molding-process language across the core polymer-shaping IPC classes. That figure counts families rather than raw documents, which neutralises inflation from continuations and multi-jurisdiction refiling of the same invention. The true current total is likely somewhat higher because publication typically lags filing by around eighteen months, so the most recent year in any count understates real activity.

Based on this dataset, growth has stalled rather than continued. Annual filings rose from 18 in 2017 to a peak of 45 in 2020, held near 32 at the 2022 midpoint, and have since tapered toward 7 in the latest partial year. Even discounting the most recent one to two years for publication lag, the 2017-2022 trajectory reads as a plateau after an earlier growth phase, not sustained expansion.

The assignee ranking is led by a recurring set of Japanese, Chinese and US-headquartered organisations, including UBE, Toray, DuPont, Mitsubishi Gas Chemical, Mitsui Chemicals and SABIC's intellectual-property entity, across 1,115 tracked families. Notably, every one of these leading assignees shows zero filings in the most recent year in this dataset, which is most plausibly explained by publication lag rather than an actual pullback. Confirming current competitive posture requires waiting for the last 18 months of filings to publish.

The receiving-office data shows Europe (EPO, 289 filings) and Japan (278) each ahead of the United States (214), with China (142), the WIPO/PCT route (54) and Canada (30) trailing behind. A clearance search or filing strategy built only around the US would miss the majority of the documented activity in this space. Given the EPO and Japan weighting, any freedom-to-operate work in polyimide molding processes should extend to those offices as a baseline, not an afterthought.

EP0431636A1, filed by UBE INDUSTRIES LIMITED, claims an extruded multi-layer polyimide film with a thin outer layer (10 µm or less) of one aromatic polyimide composition on a base layer of a different aromatic polyimide composition, produced by multi-layer extrusion molding — a casting method. It blocks work that falls within that specific layered-composition-and-casting combination, but it does not on its own cover single-layer films, non-extrusion casting routes, or layer compositions outside the claimed tetracarboxylic acid and diamine chemistries. Anyone designing near it should check layer count, thickness thresholds and the specific aromatic chemistries claimed before assuming clearance.