GFRP Pultrusion & Filament Winding Patent Landscape
ESSEF CORP holds a clear lead with 36 patent families, roughly double the next-ranked filer, in a 299-family corpus that has plateaued near its 2020 filing peak. China is the dominant filing jurisdiction, and shaping-of-plastics (B29C) accounts for the overwhelming share of IPC coverage, reflecting the process-intensive nature of both techniques.
ESSEF CORP leads a moderately concentrated field with a clear tier gap
ESSEF CORP ranks first with 36 patent families, ahead of MacLean Fogg Co at 18 and Werner Co at 13. The top five filers account for 24% of the hundred largest filers’ combined total, indicating moderate concentration rather than an oligopoly.
A visible tier gap separates ESSEF CORP from the second rank: its portfolio is twice the size of MacLean Fogg Co’s. Below rank three, portfolios drop to single-digit or low double-digit family counts, leaving a long and fragmented tail of smaller filers — many of them Chinese regional manufacturers.
| # | Applicant | Patent families | Share |
|---|---|---|---|
| 1 | ESSEF Corp | 36 | |
| 2 | MacLean Fogg Co | 18 | |
| 3 | Werner Co | 13 | |
| 4 | WUXI BAMOOD SCI & TECH | 10 | |
| 5 | TPI Composites Inc | 8 | |
| 6 | Nantong Josson New Material Technology Co Ltd | 8 | |
| 7 | Tianjin Jinmao Technology Development Co Ltd | 8 | |
| 8 | Henan Enbeis Composite Materials Co Ltd | 7 | |
| 9 | Henan Zhongsheng Composite Materials Co Ltd | 7 | |
| 10 | CertainTeed Corp | 6 |
| # | Applicant | Patent families | Share |
|---|---|---|---|
| 11 | Nanjing Sbr Composite Materials Co Ltd | 6 | |
| 12 | FPInnovations Inc | 6 | |
| 13 | Edward G Budd Manufacturing Co | 6 | |
| 14 | American Standard Inc | 6 | |
| 15 | Nantong Wuzhou Composite Materials Co Ltd | 6 | |
| 16 | Dow Global Technologies LLC | 5 | |
| 17 | Titcomb Brothers Manufacturing Inc | 5 | |
| 18 | ACF Industries Inc | 5 | |
| 19 | WERNER & COMPANY | 5 | |
| 20 | Taizhou Huadong Insulating Materials Co Ltd | 5 |
ESSEF CORP’s scale advantage, combined with a process focus on B29C 70 (fibre-reinforced composite shaping) and B29C 53 (forming by bending/winding), suggests deep procedural know-how that a challenger would need to work around rather than replicate directly.
Filings from 2024–2026 are likely under-counted due to standard patent-publication lag; the apparent softening in those years should not be read as a structural retreat from the technology. Longer-window growth, applicant concentration, and technology-route coverage are therefore more reliable signals than the latest-year bar alone.
Filing activity plateaued near the 2020 peak; B29C dominates the technology mix
Annual filing volume climbed from 15 families in 2017 to a peak of 51 in 2020, then stabilised in the 40–47 range through 2023. The technology composition is heavily weighted toward plastics-shaping processes, with downstream application classes spread thinly across civil engineering, electrical, and sporting-goods sectors.
Annual filing trend
The trend rose steeply from 2017 to 2020, held broadly flat through 2023, then shows an apparent dip in 2024–2025 that reflects publication lag rather than a real retreat. The plateau pattern is consistent with a mature technology whose core process parameters are well-covered.
↗ Hover for values · click a bar to ask EurekaTechnology composition
B29C (Shaping of plastics) dominates at 616 patent records, far ahead of all other classes. B29L, B32B, B29K, and various polymer-chemistry classes (C08L, C08K) form a secondary cluster. Application-end classes — E04C for building components, E21D for mine support, E06C for ladders, H01B for cable insulators — appear at low but meaningful counts, indicating real end-use diversification.
↗ Hover for values · click a bar to ask EurekaHighly cited patent families surfaced by the query
Citation-heavy patent families returned by the query. Use this section as citation context, not as a curated list of the most topic-specific patents.
Utility pole and attachments formed by pultrusion …
This relates to reinforced hollow utility poles, and attachments therefore, formed by pultrusion of dielectric insulating material, such as glass fiber reinforced resin, and the method of fabricating the same. (excerpt from the patent abstract)
| # | Patent | Citations |
|---|---|---|
| 1 | Filament wound railway hopper car | 127 |
| 2 | Utility pole and attachments formed by pultrusion … | 108 |
| 3 | Composite, pultruded fiberglass resinous hockey st… | 88 |
| 4 | Corrosion-resistant door and its method of manufac… | 74 |
| 5 | Method for making thermoplastic composite pressure… | 69 |
| 6 | Apparatus for winding filament about three axes of… | 64 |
| 7 | Method for producing glass fiber reinforced plasti… | 62 |
| 8 | Method and apparatus for forming in-line core-fill… | 60 |
Ranked by total forward citations. Citation counts favour older and broadly cited patent families, and broad or adjacent patents may appear when they match the search scope. Treat this section as citation context, not as a curated list of the most topic-specific patents. Some patent titles may be shown in their original, non-English language where an accurate translation could not be guaranteed.
What the patent structure means for R&D investment decisions
The corpus shows a mature core process layer and a fragmented application layer, pointing toward differentiation opportunities in end-use integration rather than in primary forming methods.
Field is at plateau maturity — core process IP is densely covered
The lifecycle stage is Maturity: annual filings have plateaued near the 2020 peak of 51 families. New entrants will find the core B29C 70 and B29C 53 process space well-occupied by ESSEF CORP and peers. R&D differentiation is more viable in material formulation (C08L, C08K) and end-use integration than in primary forming methods.
Lifecycle: MaturityModerate concentration with a pronounced leader gap
The top five filers hold 24% of the hundred largest filers’ combined total, which is moderate but not extreme. The gap between ESSEF CORP (36 patent families) and MacLean Fogg Co (18) is large enough that a challenger aiming for the top rank would need a sustained multi-year filing programme. The fragmented long tail of Chinese regional manufacturers signals that the application space remains contestable.
Concentration: moderateMinimal co-filing activity — one recorded partnership
Only one co-applicant pair appears in the evidence: TPI Composites Inc and the University of Tennessee Research Foundation, with one jointly filed family. This near-absence of collaborative filings is atypical for a manufacturing process field and suggests most players protect IP independently. Academic-industry joint development remains an underused route that could be leveraged to access process-optimisation know-how.
Collaboration: nascentChina leads filing volume; US and EPO remain important validation markets
China accounts for 307 patent records, ahead of the United States at 121 and Europe (EPO) at 34. Canada at 32 and Japan at 23 form a secondary tier. The China lead reflects both domestic manufacturing scale and active filing by regional composites firms. Companies targeting global infrastructure or construction markets should validate coverage in the US and EPO jurisdictions, where incumbent positions are less dense.
Geography: China-ledGo beyond the landscape: Eureka’s TRIZ Solution agent breaks down an R&D problem and returns patented concept solutions, each with a technical approach and cited patent & literature evidence.
| Applicant | Collaborator | Co-filings |
|---|---|---|
| TPI Composites Inc | University of Tennessee Research Foundation | 1 |
Co-filing pairs, ranked by the number of jointly-filed patent families.
ESSEF CORP leads on process breadth; MacLean Fogg Co anchors the insulator segment
The top two filers differ in technology emphasis: ESSEF CORP covers composite-forming processes broadly, while MacLean Fogg Co combines forming methods with a strong electrical-insulator application focus.
ESSEF CORP
ESSEF CORP holds 36 patent families — the largest portfolio in the corpus by a wide margin. Its technology emphasis centres on B29C 70 (fibre-reinforced composite shaping, 36 records), B29C 53 (forming by bending/winding, 34 records), and B29C 49 (blow moulding, 17 records), indicating broad coverage of both primary forming routes. No momentum signal is available for ESSEF CORP in the recent-period data, consistent with an established, mature portfolio rather than an active filing surge.
families: 36MacLean Fogg Co
MacLean Fogg Co holds 18 patent families and focuses equally on B29C 70 composite shaping and H01B 17 (cables, conductors and insulators), each with 18 records, supplemented by B29C 45 (injection moulding, 10 records). This dual emphasis on forming process and electrical insulation application distinguishes it from ESSEF CORP’s broader forming orientation and positions it firmly in the utility and power-infrastructure end-use segment.
families: 18| Applicant | Recent (3 yrs) | Trend |
|---|---|---|
| TPI Composites Inc | 1 | ▲ new entrant |
| Henan Zhongsheng Composite Materials Co Ltd | 7 | ▲ new entrant |
Under-served adjacent branches worth monitoring
Several IPC branches appear at low share relative to the dominant B29C class. Two are highlighted below as observations of relative sparsity with plausible technical linkage to GFRP pultrusion and filament winding.
F17C · Pressure vessels & gas storage
F17C carries only 3 patent records in the corpus despite filament winding being the dominant manufacturing route for composite pressure vessels used in compressed natural gas and hydrogen storage. The sparsity likely reflects filing under the primary B29C class rather than the end-use class, but it also indicates that application-specific claims tailored to pressure-vessel performance — burst pressure, liner-interface design, fatigue cycling — remain relatively sparse. An entrant with hydrogen storage or NGV tank expertise could explore this adjacent branch to establish differentiated end-use coverage.
Search this in Eureka →F03D · Wind motors (wind turbines)
F03D appears at only 6 patent records despite wind turbine blades being a high-profile application of both pultrusion (spar caps) and filament winding (nacelle components). The low count may reflect routing of blade IP under B29C or under wind-specific subclasses outside this corpus scope. As spar-cap pultrusion scales to longer blades, the intersection of process optimisation and aerodynamic-structural design represents a technically plausible area where focused filings under F03D could establish a differentiated position.
Search this in Eureka →How leading applicants differ by technology route
Route coverage across the main technology branches in the current evidence set.
| Player | B29C 70 · Shaping of plastics | B29C 53 · Shaping of plastics | B29L 31 · Plastic products (index) | C08J 5 · Polymer processing & solutions | C08K 7 · Use of additives in polymers |
|---|---|---|---|---|---|
| ESSEF Corp | Strong · 36 | Strong · 34 | Absent | Absent | Absent |
| MacLean Fogg Co | Strong · 18 | Moderate · 8 | Absent | Absent | Absent |
| Werner Co | Strong · 9 | Absent | Absent | Moderate · 2 | Absent |
| Wuxi Bamood Sci & Tech Co Ltd | Strong · 10 | Absent | Absent | Absent | Absent |
| TPI Composites Inc | Strong · 8 | Absent | Moderate · 2 | Absent | Absent |
| Composite Solutions | Strong · 7 | Absent | Moderate · 2 | Absent | Absent |
Frequently asked questions
ESSEF CORP leads with 36 patent families, roughly double the portfolio of the second-ranked filer, MacLean Fogg Co, which holds 18 patent families.
Moderate concentration: the top five filers account for 24% of the hundred largest filers’ combined total. A long tail of smaller filers — many based in China — makes the application layer contestable.
No. The lifecycle stage is Maturity. Annual filing volume peaked at 51 families in 2020 and has plateaued in the 40–47 range since. Apparent softening in 2024–2025 reflects publication lag rather than a real decline.
China leads at 307 patent records, followed by the United States at 121, Europe (EPO) at 34, and Canada at 32. Japan accounts for 23 records.
B29C (Shaping of plastics) is overwhelmingly dominant at 616 patent records. Secondary clusters include B29L, B32B, B29K, and polymer-chemistry classes C08L and C08K. Application-end classes such as E04C (building components), E06C (ladders), and H01B (electrical insulators) appear at lower but meaningful counts.
Evidence shows only one recorded co-applicant pairing: TPI Composites Inc and the University of Tennessee Research Foundation, with one jointly filed family. Co-filing activity in this field is minimal overall.
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