Filament Winding Patents: Who Leads, Where the Gaps Are 2026
- Filing has cooled since 2021. The peak year of 13 records has given way to a flat-to-declining trend through 2022, with the most recent year understated by publication lag.
- The top 10 hold just over half the field. 88 of 171 records in scope — 51.5% — sit with the ranked leaders, leaving a long tail of single- and few-filing entrants.
- Claims concentrate hard in one subclass. B29C shaping-of-plastics covers 92.4% of the 171 records, while pressure-vessel-specific F17C appears in only 11.7% — a gap between the winding process and the vessel application.
What this landscape covers
Filament winding is the process of laying continuous fibre under controlled tension onto a rotating mandrel to build a composite shell, most commonly a pressure vessel. This landscape covers 171 patent records published between 2015 and 2026 that combine filament-winding process terms with claim language around winding pattern, fibre tension, mandrel design, burst strength or void content, filtered to the shaping-of-plastics and pressure-vessel IPC classes. The scope is deliberately narrow: it isolates process and tooling claims rather than every composite-vessel patent in general.
Filing in this set peaked in 2021 and has flattened since, with the most recent year understated because publication typically lags filing by around 18 months. The assignee base is broad — 86 companies appear in the ranking — but a small group of repeat filers accounts for roughly a third of all records, pointing to a field with an established core and a wide, thinly-filed periphery.
Filing trend and technology composition
Two views of the same 171 records: how filing has moved year over year, and which IPC subclasses carry the claim volume.
Filing trend, 2017-2026
Filings rose from 7 in 2017 to a peak of 13 in 2021, held near that level at 12 in 2022, then eased off. The final one or two years will read low regardless of real activity, because publication lags filing by roughly 18 months — treat the tail as provisional, not as a real drop-off.
IPC subclass distribution
B29C (shaping of plastics) appears in 92.4% of the 171 records, confirming this is fundamentally a process-patent set. B65H (web/filament handling) at 29.8% and C08G (condensation polymers) at 17.5% are the next-heaviest classes. F17C, the pressure-vessel-specific class, covers only 11.7% — most filers claim the winding process itself rather than the finished vessel, which is where application-specific claim space still sits open.
Shares are the percentage of the 171 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Filament Winding for Composite Vessels with Eureka
This page is one run against one query. Ask Eureka your own question about filament winding for composite vessels and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited records in this set
EP2425960A4 — Filament winding device and filament winding method
Filed by Toyota, this record describes a filament winding device and method aimed at controlling winding parameters during mandrel-based composite vessel construction.Rendered separately with full bibliographic detail; discussed in the chat answers on claim scope and design-around options.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4867834A | Filament winding system | 150 |
| 2 | US5266139A | Continuous processing/in-situ curing of incrementally applied resin matrix composite materials | 136 |
| 3 | US4892764A | Fiber/resin composites, and method of making the same | 134 |
| 4 | US20050038222A1 | Process for filament winding | 85 |
| 5 | US4078957A | Filament winding apparatus and method | 75 |
| 6 | US4783232A | Filament winding using a rotationally molded inner layer | 71 |
| 7 | US5213275A | Reeding edge for securing in place fiber band during filament winding operation | 52 |
| 8 | US20030052212A1 | Filament winding apparatus and methods of winding filament | 50 |
| 9 | — | On-line consolidation of filament wound thermoplastic parts | 45 |
| 10 | US4921557A | Fabrication by filament winding with an elastomeric material | 40 |
Citation counts reflect influence within the searched corpus and skew toward older filings — read them as a signal of foundational status, not current commercial relevance.
Publication numbers are shown where the record carries one (9 of 10 rows); clicking a row searches Eureka by that number.
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A core group, not a monopoly
The top 5 assignees combined hold 55 of 171 records — 32.2% of the field. That is real concentration, but it leaves two-thirds of filings spread across a much wider set of companies, so freedom-to-operate checks cannot stop at the leaders.
Flat, not accelerating
Filings held near their peak through 2022 before the trend eased, and none of the tracked leading assignees show fresh activity in the latest year. That pattern is consistent with a maturing process technology rather than one still attracting new entrants at pace.
Process claims dominate; vessel claims don't
Shaping-of-plastics claims (B29C) cover the large majority of records, while pressure-vessel-specific claims (F17C) trail far behind at 11.7%. Claim language tied specifically to vessel performance and certification is comparatively under-filed.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to filament winding for composite vessels, with the prior art for and against each one.
Who is filing, and where the tension sits
The leader board is broad rather than dominated by one firm, and the geography of filing shows where the commercial pressure is concentrated.
A lead without a runaway gap
The top-ranked assignee holds 13 records against a fifth-place figure of 9 and a tenth-place figure of 5 — a gradual taper, not a cliff. That shape suggests several firms are filing at comparable intensity rather than one company dictating the field.
US and Japan anchor the filing map
The United States leads with 61 filings, followed by Japan at 26 and the EPO at 24. India's 15 filings and 12 PCT filings point to filers building coverage beyond the traditional US-Japan-Europe axis.
Co-filing is rare and mostly intra-group
Only 8 co-assignee pairs appear in the dataset, and the strongest links are between related entities within the same corporate group rather than cross-company joint ventures. Genuine external collaboration on filed IP is the exception here, not the rule.
| Assignee | Recent year | YoY |
|---|---|---|
| Hercules Inc. | 0 | — |
| Loctite Corp. | 0 | — |
| Plantics Holding B.V. | 0 | — |
| Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation) | 0 | — |
| Hexagon Technology AS | 0 | — |
| Viritech Ltd. | 0 | — |
| Sumitomo Electric Industries, Ltd. | 0 | — |
| Toyota Motor Sales, U.S.A., Inc. | 0 | — |
Where to take this next
The dataset points to specific follow-up work rather than a single conclusion.
Check freedom-to-operate against the tail, not just the leaders
With only 32.2% of records held by the top 5 assignees, a clearance search that stops at the best-known filers misses two-thirds of the field.
Run a freedom-to-operate search in EurekaWatch the F17C gap
Pressure-vessel-specific claims sit well below process claims in filing density — a candidate area for new claim drafting before it fills in.
Explore F17C filings in EurekaRe-check citation leaders for design-around risk
The most-cited records date back decades; confirm which underlying claims are still in force before relying on the citation count alone.
Pull citation trees in EurekaCommon questions on filament winding patents
The leading assignee in this 171-record dataset holds 13 records, with the fifth-ranked firm at 9 and the tenth-ranked firm at 5 — a gradual taper rather than one company dominating. The top 5 assignees together account for 32.2% of all records in scope, and the top 10 for 51.5%. That leaves close to half the field held by a long tail of firms filing only one or a few records each, so a competitive review needs to look well past the visible leaders.
Filing rose from 7 records in 2017 to a peak of 13 in 2021, held near that level at 12 in 2022, and has eased since. None of the leading assignees tracked show fresh filings in the most recent year. Some of that apparent slowdown is a publication-lag artefact — filing typically lags publication by around 18 months, so the last one to two years will always look thinner than they eventually turn out to be — but the flattening from 2021 to 2022 predates that lag and looks like a genuine plateau.
The large majority of records — 92.4% of the 171 in scope — sit in B29C, the shaping-of-plastics class, confirming this is primarily a process-patent field. B65H (web and filament handling) covers 29.8%, and C08G (condensation polymers, relevant to resin systems) covers 17.5%. F17C, the pressure-vessel-specific class, appears in only 11.7% of records, which is notably lower than the process classes and marks where vessel-application claims are comparatively thin.
EP2425960A4 is a Toyota filing for a filament winding device and method, covering control of winding parameters during mandrel-based construction of composite vessels. It is one of the more recent representative filings in this dataset rather than one of the oldest, most-cited records. Anyone designing new winding equipment or control logic should read its claims directly rather than relying on the abstract, since device and method claims in this class are often drafted narrowly around specific control mechanisms.
The clearest gap sits between process claims and vessel-application claims: B29C process filings cover 92.4% of records while F17C vessel-specific filings cover only 11.7%, meaning much of the winding process itself is well claimed but performance- and certification-linked vessel claims are less crowded. Co-assignee collaboration is also rare — only 8 pairs across 171 records — suggesting joint filings between unrelated companies are an underused route. Sub-areas like in-situ cure monitoring, void-content sensing, and non-cylindrical mandrel removal show lower claim density than the core winding-pattern and tension-control claims.
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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.