Carbon Fiber Composite Patents: Who Leads, Where Filings Cool 2026
- Filings have cooled since the 2019 peak. 464 families in 2019 fell to 366 at the 2022 midpoint, and the trend line has stayed flat-to-declining since — this is an occupied field, not a growing one.
- Japan dominates the receiving-office mix. 2,634 records filed at the Japanese office outpace China (2,020), the EPO (1,322) and the US (1,230), reflecting where precursor-fiber and sizing-agent chemistry is anchored.
- Momentum has stalled even among the historic leaders. Toray shows only 2 families in the latest year (-67% YoY) and Mitsubishi Chemical shows 0 (-100% YoY) — recent-year activity is thin across the assignees that built the core patent estate.
A mature claim space built on fiber chemistry, not just molding
Carbon fiber and composite material patenting sits across two connected layers: the fiber chemistry that determines tensile modulus and interfacial adhesion, and the shaping and layup processes that turn fiber into a finished part. The search corpus underlying this page pulls from D01F9 (precursor and filament features), C08J5 (polymer processing and composite solutions) and B29C70 (shaping of reinforced plastics), which is why sizing-agent and prepreg claims sit alongside molding and laminate claims in the same dataset.
8,884 patent families are tracked here, spanning filings from 2015 through the 2026 data cut-off. Because publication typically lags filing by around 18 months, the most recent year understates real filing activity and should be read as a floor, not a ceiling.
Filing trend and technology composition
The filing curve and the IPC breakdown together show a field that built out its core chemistry early and has since settled into incremental filing rather than expansion.
A 2019 peak followed by a plateau
Filings rose from 356 in 2017 to a peak of 464 in 2019, then eased back to 366 at the 2022 midpoint and have stayed flat or declined since. That shape is consistent with a technology whose core claim space — precursor fiber composition, sizing-agent chemistry, prepreg lay-up — was staked out in the late 2010s, with newer filings now competing for narrower gaps.
Polymer processing and fiber chemistry dominate
C08J (polymer processing and solutions) and D01F (filament and fiber features) lead the IPC mix at 3,671 and 3,528 records respectively, ahead of B29C shaping claims at 2,855. The smaller counts in C08L, C08K, D06M, B32B and B29K mark denser but narrower sub-fields — additive formulation, textile treatment and laminate structure — where a first-filer has more room to define the claim.
Shares are the percentage of the 8,884 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Carbon Fiber and Composite Materials with Eureka
This page is one run against one query. Ask Eureka your own question about carbon fiber and composite materials and every answer comes back with the patent numbers behind it.
Try EurekaThe prior art that still gets cited
Sizing-agent-coated carbon fiber bundle for prepreg production
A sizing agent-coated carbon fiber bundle has a sizing agent containing an aliphatic epoxy compound (C) and an aromatic epoxy compound (D) coated on the carbon fiber bundle, wherein the carbon fiber in the bundle is one which exhibits, when measured by single-fiber composite fragmentation method, a number of fiber breaks of at least 2.0/mm when apparent single-fiber stress is 15.3 GPa and a number of fiber breaks of up to 1.7/mm when the apparent single-fiber stress is 12.2 GPa.Filed by Toray Industries, Inc., published 2015-12-17 as US20150361591A1.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US6503856B1 | Carbon fiber sheet materials and methods of making and using the same | 240 |
| 2 | US20050230029A1 | Continuous fiber reinforced composites and methods, apparatuses, and compositions for making the same | 222 |
| 3 | US20020009935A1 | Core-crush resistant fabric and prepreg for fiber reinforced composite sandwich structures | 213 |
| 4 | JP1989104624A | Prepreg using resin fine particles | 193 |
| 5 | JP2007016121A | Prepreg for composite material and composite material | 181 |
| 6 | US20030044593A1 | Continuous fiber reinforced composites and methods, apparatuses, and compositions for making the same | 177 |
| 7 | JP1999241230A | Carbon fiber, precursor fiber for carbon fiber, composite material and production of carbon fiber | 162 |
| 8 | US6354963B1 | Golf club head | 161 |
| 9 | US5518836A | Flexible carbon fiber, carbon fiber electrode and secondary energy storage devices | 153 |
| 10 | US5413866A | High performance carbon filament structures | 151 |
Citation counts favour older filings simply because they have had longer to accumulate citations inside this corpus — read them as a signal of influence on later filers, not as a ranking of current technical importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three patterns matter more than any single ranking: where claim density concentrates, how citation age skews the most-cited list, and how thin recent-year activity has become even for the historic leaders.
Polymer processing is the most crowded layer
C08J and D01F together account for over 7,000 of the 8,884 records, meaning fiber-composition and processing claims are the densest part of the space. New filings here are competing against a large installed base rather than opening fresh ground.
The 2019 peak has not been retested
Filing volume fell from its 2019 high through the 2022 midpoint and the trend line has stayed flat or declining since, a pattern more consistent with claim consolidation than with an emerging technology still attracting new entrants.
The most-cited prior art predates the current filing wave
The five most-cited records in the corpus include filings as old as a 1989 Japanese prepreg patent, which is expected inside any searched corpus — older records simply have had more time to accumulate citations. Treat the list as a map of foundational technique, not a guide to what is being actively litigated or licensed today.
Even the leaders show thin recent filing
Toray recorded only 2 families in the latest year against a prior-year decline of 67%, and Mitsubishi Chemical shows zero with a 100% year-on-year drop. Given the 18-month publication lag, some of this is an artefact of timing, but the multi-year plateau suggests it is not timing alone.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to carbon fiber and composite materials, with the prior art for and against each one.
Who holds the estate, and who has gone quiet
A small group of Japanese fiber and chemicals producers anchors the historic filing volume. Recent-year momentum data shows that anchor position has not translated into continued active filing — most of the named leaders show flat or falling counts in the latest tracked year.
Still filing, but at a fraction of past pace
Toray's representative filing on sizing-agent chemistry (US20150361591A1) sits among the dataset's technical benchmarks, but its latest-year count of 2 families, down 67% year-on-year, shows the company's filing intensity has cooled sharply from its earlier pace.
Cross-entity filing runs through steel-linked chemical arms
The strongest co-assignee pair in the dataset links Nippon Steel with its chemical-materials subsidiary at 50 joint filings, well ahead of the Toho Rayon and Toho Beslon pairing at 26. That pattern points to internal group filing rather than cross-company joint development.
Teijin keeps a minimal but active filing presence
Teijin shows 1 family in the latest tracked year, alongside a co-assignee link to its European carbon subsidiary (13 joint filings) — a modest but non-zero signal compared with assignees like Mitsubishi Rayon and Toho Tenax, which register zero latest-year activity.
| Assignee | Recent year | YoY |
|---|---|---|
| Toray Industries, Inc. | 2 | -67% |
| Teijin Limited | 1 | — |
| Mitsubishi Rayon Co., Ltd. | 0 | — |
| Mitsubishi Chemical Corporation | 0 | -100% |
| Toho Tenax Co., Ltd. | 0 | — |
| Toho Rayon Co., Ltd. | 0 | — |
| Tonen Corporation | 0 | — |
| Nippon Steel Corporation | 0 | — |
Where to take this analysis
The dataset points to a field with dense core claims and thinning recent activity — the next step is usually a narrower, claim-level check rather than another broad landscape.
Check freedom-to-operate on a specific sizing or prepreg formulation
Run the exact chemical composition or process parameter you plan to claim against the dense C08J/D01F cluster before drafting, since that layer holds the majority of records.
Explore claim-level FTO in EurekaTrack the assignees still filing, not just the historic leaders
Recent-year momentum shows most named leaders at flat or declining counts — build a monitoring set around whoever is still active rather than the biggest historic portfolio.
Set up assignee monitoring in EurekaTest the under-claimed branches for a first-mover filing
Recycled-fiber sizing chemistry and additive-modified prepreg formulations show lower density than core molding claims — a targeted search will confirm how open they really are.
Run a white-space search in EurekaCommon questions on carbon fiber and composite patents
Japanese fiber and chemicals producers anchor the historic filing volume in this space, with Toray Industries holding one of the dataset's most technically referenced filings on sizing-agent chemistry. That said, recent-year momentum data shows most of the historically dominant assignees, including Toray and Mitsubishi Chemical, filing far fewer families in the latest tracked year than in their peak years. A ranking based purely on cumulative family count will overstate how active any single company is today, so pair it with recent-year filing counts before drawing conclusions.
No, not by filing volume. The dataset shows filings peaking at 464 families in 2019, easing to 366 at the 2022 midpoint, and staying flat or declining through the most recent tracked years. Some of the most recent-year dip is a publication-lag artefact, since filings typically take around 18 months to publish, but the multi-year plateau before that points to genuine slowing rather than a reporting gap alone.
A sizing agent is a chemical coating applied to carbon fiber to protect it during handling and to control how well it bonds to the surrounding resin matrix, a property called interfacial adhesion. It matters for patent purposes because sizing-agent composition is one of the most heavily claimed elements in this dataset's D01F and C08J subclasses, and small changes in epoxy compound ratios or coating processes are frequently the basis for distinct claims. Toray's representative filing in this dataset, US20150361591A1, claims a specific aliphatic-plus-aromatic epoxy sizing formulation defined by fiber-breakage test results, illustrating how narrow and test-specific these claims can get.
Japan leads the receiving-office mix in this dataset with 2,634 records, ahead of China at 2,020, the European Patent Office at 1,322, the United States at 1,230, South Korea at 480 and WIPO/PCT filings at 316. That distribution reflects where precursor-fiber and sizing-agent chemistry development has historically concentrated, rather than where composite parts are ultimately manufactured or sold. A company evaluating freedom-to-operate risk should weight Japanese and Chinese filings accordingly, even if its own manufacturing footprint is elsewhere.
The density data points to a few narrower branches with comparatively fewer filings relative to the core fiber-composition and molding claims: recycled carbon fiber sizing chemistry, low-cost precursor fiber routes, and additive-modified prepreg formulations among them. These are not verified gaps, only areas where relative filing density is lower in this dataset, so a targeted freedom-to-operate and prior-art search on the specific claim scope is still the necessary next step before committing to a filing strategy.
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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.