Polyimide Coating and Film Patents: Leaders, Trends & White Space 2026
- Filing has cooled since its 2019 peak of 752. the 2026 count of 50 (partial year) sits well below the 2017 baseline of 509, and the leading assignees are pulling back double digits year-on-year rather than pushing new filings.
- Polymer processing and condensation-polymer chemistry dominate the claims. C08J and C08G together outweigh coating-specific IPC classes like C09D by more than 4-to-1, showing the fight is over the polymer itself, not the coating step.
- China now receives more filings than Japan or the US. 2,905 Chinese filings versus 2,704 Japanese and 1,457 US filings mark a shift in where this technology is being protected, even as legacy Japanese and Korean assignees slow down.
Filing growth compares 2021 (641 records) with 2024 (358) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 11,555 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Polyimide coating and film patents span a search space defined by polyimide film, PI, and closely related terms such as spin-coated PI and solution casting film, cross-referenced against IPC classes covering polymer solutions, polyimide-specific coating compositions, and polyimide-based molding compounds. The corpus runs from 2015 through a partial 2026 and contains 11,555 patent families, giving a reasonably complete picture of a decade of filing activity in a mature specialty-polymer segment.
Because publication typically lags filing by around 18 months, the last one to two years in any trend chart will always look thinner than they eventually turn out to be. That lag matters here specifically because the visible slowdown after 2019 is real in direction but understated in the most recent years shown.
Filing trend and technology composition
Two views of the same dataset: how filing volume has moved year over year, and which parts of the IPC system carry the claim density.
A decade past its peak
Filings rose from 509 in 2017 to a peak of 752 in 2019, then declined toward a partial-year count of 50 in 2026. The 2022 midpoint of 620 sits below the peak, confirming the decline is not a single-year dip but a multi-year contraction in new filing activity.
Polymer chemistry outweighs coating application
C08J (polymer processing and solutions) and C08G (condensation polymers) each cover the majority of records, well ahead of C09D (coatings, paints and inks) or B32B (layered products). The claim density sits in the base polymer and its processing, not in how it is applied as a coating — a distinction that matters for anyone drafting around the space.
Shares are the percentage of the 11,555 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Polyimide Coating and Film with Eureka
This page is one run against one query. Ask Eureka your own question about polyimide coating and film and every answer comes back with the patent numbers behind it.
Try EurekaThe patents everyone in this space cites
US20220127427A1 — Method for producing polyimide film
A method for producing a polyimide film includes: providing a polyimide coating solution; providing a high temperature resistant polyester substrate; and coating the polyimide coating solution on the high temperature resistant polyester substrate, so that a polyimide wet coating is formed on the high temperature resistant polyester substrate; implementing a first baking step, which includes: baking the polyimide wet coating at a first temperature of between 60° C. and 130° C. to remove a part of organic solvent in the polyimide wet coating; implementing a second baking step, which includes: baking the polyimide wet coating at a second temperature of between 140° C. and 220° C. to remove a re…Filed by Nan Ya Plastics Corporation, published 2022-04-28.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4595548A | Process for preparing essentially colorless polyimide film containing phenoxy-linked diamines | 250 |
| 2 | US6232428B1 | Essentially colorless, transparent polyimide coatings and films | 207 |
| 3 | JP2008163107A | Optical member | 198 |
| 4 | JP1984219330A | Polyimide, manufacture and use | 197 |
| 5 | US4603061A | Process for preparing highly optically transparent/colorless aromatic polyimide film | 184 |
| 6 | JP2000187111A | Color filter substrate | 179 |
| 7 | US5164460A | Polyimide composite material and process for producing the same | 173 |
| 8 | JP1994056992A | Polyimide film | 172 |
| 9 | US4880895A | Polyimide film-forming polyamide acid solution | 136 |
| 10 | US4014834A | Aqueous solutions of polyamide acids which can be precursors of polyimide polymers | 133 |
Citation counts are drawn from a searched corpus and skew toward older filings by construction — read them as a signal of influence on later filers, not of present-day relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Four cuts of the same corpus, each pointing at a different part of the decision a reader has to make: where to file, who to track, and what to expect from the incumbents.
The wave has passed
Annual filings peaked at 752 in 2019 and have declined steadily since, with the 2026 partial-year count sitting at 50. Even allowing for publication lag, the direction across the 2022 midpoint of 620 is down, not flat.
China leads the receiving-office count
China now receives more polyimide coating and film filings than Japan, the traditional stronghold for this chemistry, with the US and South Korea trailing both.
The claims sit in the polymer, not the coating step
Polymer processing and solution chemistry (C08J) and condensation polymer synthesis (C08G) each carry far more records than coating-specific IPC class C09D, meaning most protected ground is upstream of application.
Established filers are stepping back
Assignees that built large portfolios in past years — from Kaneka to UBE to Du Pont-Toray — show sharp year-on-year declines or zero filings in the latest year, a pattern consistent across the leaderboard rather than isolated to one firm.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to polyimide coating and film, with the prior art for and against each one.
A leaderboard with a thinning top
The assignee ranking is long-tailed: a handful of Japanese and Korean specialty-polymer makers built the deepest portfolios over the past decade, and several of them are now filing at a fraction of their former pace. New entrants exist, but the recent-year momentum data shows contraction more often than expansion.
Japanese and Korean specialty makers are pulling back
Firms such as Kaneka, UBE, and Du Pont-Toray, which anchor several of the strongest co-assignee pairs in this dataset, show some of the steepest year-on-year declines in the corpus, several reaching zero filings in the most recent year.
Joint filing is limited but structured
Only ten co-assignee pairs appear in the dataset, concentrated around corporate affiliate relationships such as UBE with Gunze, and Kolon Industries with Kolon entities, suggesting joint R&D is the exception, not the rule.
Smaller specialists still file, just less
Even the more active recent filer in the momentum table, PI Advanced Materials, is down 74% year-on-year, indicating that slower filing is a field-wide pattern rather than a single company retreating.
| Assignee | Recent year | YoY |
|---|---|---|
| PI Advanced Materials Co., Ltd. | 5 | -74% |
| Kaneka Corporation | 1 | -83% |
| Mitsubishi Gas Chemical Company, Inc. | 1 | -89% |
| UBE Corporation | 0 | -100% |
| LG Chem, Ltd. | 0 | — |
| Du Pont-Toray Co., Ltd. | 0 | -100% |
| E.I. du Pont de Nemours and Company | 0 | — |
| Kolon Industries, Inc. | 0 | — |
Where to take this analysis
The trend and leaderboard data point to a mature, consolidating field. The next questions are usually about freedom to operate and where the remaining claim gaps sit.
Map freedom to operate against the top-cited patents
The most-cited records in this corpus, several dating to the 1980s, still anchor claim scope in colorless and transparent polyimide film chemistry. Run a claim chart before committing to a formulation in that space.
Explore in Patsnap EurekaTrack the incumbents that are still filing
Momentum has slowed almost everywhere, but not to zero. Watching which assignees keep filing, even at reduced volume, is a better signal than watching total portfolio size.
Explore in Patsnap EurekaCheck the under-claimed sub-areas before drafting
IPC density is uneven across this dataset. Sub-areas tied to flexible display substrates and FPC lamination show comparatively thinner coverage than the core polymer classes.
Explore in Patsnap EurekaCommon questions about polyimide coating and film patents
The ranking in this dataset is led by a cluster of Japanese and Korean specialty-polymer manufacturers, including firms such as Kaneka, UBE, and Kolon Industries, alongside PI Advanced Materials and Du Pont-Toray. However, several of these same firms show the steepest year-on-year declines in recent filings, so leading by cumulative volume does not mean leading by current activity. Anyone assessing this space should look at both the historical leaderboard and the recent-year momentum figures together.
No. Filings peaked in 2019 at 752 and have declined since, with the 2026 partial-year figure at 50. The 2022 midpoint of 620 confirms this is a sustained decline rather than a single down year, though the very latest years are always understated because publication lags filing by roughly 18 months. The overall pattern is one of a maturing field with fewer new entrants rather than an expanding one.
It is a method patent from Nan Ya Plastics Corporation describing a two-stage baking process for producing polyimide film: coating a polyimide solution onto a heat-resistant polyester substrate, then baking first at 60-130°C to remove solvent and second at 140-220°C for a further step. It is process-specific rather than a composition-of-matter claim, so its scope is tied to that particular temperature-staged coating and baking sequence rather than to polyimide film chemistry broadly. Anyone using a similar two-stage bake on a polyester carrier film should review it directly rather than assume it only affects Nan Ya's own products.
The IPC distribution shows heavy concentration in polymer processing (C08J) and condensation polymer synthesis (C08G), with comparatively thinner coverage in application-specific areas such as flexible display substrates, FPC adhesion layers, and high-temperature release-liner coatings. These are not unclaimed, but they carry markedly less density than the core polymer classes, which is where a first claim would face the least crowded prior art. Confirming this requires a targeted freedom-to-operate search rather than relying on IPC counts alone.
China leads with 2,905 filings in this dataset, ahead of Japan at 2,704 and the United States at 1,457, with South Korea, the EPO, and Taiwan following. This marks a shift from the historical center of gravity, since much of the most-cited foundational art in this field originates from Japanese and US filings dating back to the 1980s. Current filing activity and historical influence are concentrated in different places, which matters for deciding where to prioritize a search.
High filing density in earlier years does not mean the underlying technology stopped being commercially relevant; it means much of the claim space in core polymer chemistry and processing was already occupied by incumbents. A slowdown in new filings is consistent with a maturing field where product use continues but the patentable headroom for new compositions has narrowed. Companies still active, per the momentum data, tend to file selectively rather than broadly.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.