Aramid Paper for Electrical Insulation Patents: Leaders & Trends 2026
- One filer dominates the founding art. the leading assignee holds 20 of the records in a 17-company ranking, with a long tail of single- and double-filing entrants behind it.
- Filing activity has gone flat since its 2017 peak. the trend recorded 7 filings in 2017 and had fallen to 0 by the 2022 midpoint, with no recovery visible before the data cut-off.
- Insulation claims sit alongside laminate and PCB classes. 35.9% of the 39 records in scope carry an H01B insulator classification, but layered-product (B32B) and printed-circuit (H05K) codes appear almost as often.
What this landscape covers
Aramid paper used as electrical insulation sits at the intersection of paper chemistry and motor or transformer design: a nonwoven or wet-laid sheet of para-aramid fibrid and shortcut fibre, calendered to a target density and grammage, then impregnated with varnish or resin to serve as a slot liner, phase barrier or wrap in traction motors, generators and transformers. The patent record in scope is built from a targeted query combining aramid paper composition language with claim terms tied to dielectric strength, thermal class, impregnation, dimensional stability and traction-motor slot-liner use, filtered to D21H (pulp and paper compositions), H01B (insulators and conductors) and H02K (dynamo-electric machines).
The 39 records in scope span 2015 to the July 2026 cut-off. Because publication typically lags filing by around 18 months, the most recent year on the trend chart is understated and should not be read as a real drop-off on its own.
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Filing trend and technology mix
Two views of the same 39-record corpus: how filing activity has moved over time, and which IPC subclasses the claims actually sit in.
A 2017 peak with no rebound
Filings peaked at 7 in 2017 and had fallen to 0 by the 2022 midpoint, a pattern consistent with flat-to-declining activity rather than a cyclical dip. Recent years should be read with the 18-month publication lag in mind before concluding the field has gone quiet.
Paper composition dominates, but insulation is not the only lens
D21H (pulp and paper compositions) appears in 79.5% of the 39 records, confirming that most claims are anchored in the paper's own formulation rather than in the end device. H01B insulator claims cover 35.9% of records, while B32B laminate claims (46.2%) and H05K printed-circuit claims (38.5%) show the paper is claimed almost as often as a layered or electronics substrate as it is as a dedicated insulator.
Shares are the percentage of the 39 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Aramid Paper for Electrical Insulation with Eureka
This page is one run against one query. Ask Eureka your own question about aramid paper for electrical insulation and every answer comes back with the patent numbers behind it.
Try EurekaThe documents that anchor this field
US20190376237A1 — Aramid paper suitable for use in electronic applications
Claims an aramid paper for electronic applications defined by density (0.20-0.65 g/cm3) and grammage (30-280 g/m2), built from 10-40 wt.% aramid shortcut (linear density 2.6 dtex or lower, length 0.5-25 mm) and 10-90 wt.% aramid fibrid, with both components at least 70 wt.% para-aramid. The filing ties this composition to low CTE, homogeneity and dimensional stability from good resin adhesion and penetration.Filed by Teijin Aramid B.V., published 2019-12-12.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | WO2005103376A1 | Aramid paper blend | 45 |
| 2 | US20050230072A1 | Aramid paper blend | 36 |
| 3 | WO2004031466A1 | Aramid paper laminate | 29 |
| 4 | WO2009108672A2 | Core having a high shear strength and articles made from same | 14 |
| 5 | US20100109469A1 | Capped stator core wedge and related method | 13 |
| 6 | CN114214866A | 一种磁损耗芳纶纸、吸波蜂窝及制备方法 | 10 |
| 7 | US20040071952A1 | Aramid paper laminate | 8 |
| 8 | JP2014199733A | Ion conductive membrane | 6 |
| 9 | EP1756360B1 | Aramid paper blend | 6 |
| 10 | US20040072000A1 | Aramid paper laminate | 6 |
Ranked by citation count within this searched corpus; older filings accumulate more citations simply by being available longer, so treat this as a signal of influence rather than current relevance.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for filing strategy
Four read-outs from the citation, classification and assignee data that matter more for a filing decision than the raw counts alone.
The oldest blend patents still carry the most weight
The two most-cited records in this corpus, WO2005103376A1 and US20050230072A1, both claim an aramid paper blend and predate almost everything else in scope. New filings in the core composition space are still filing around this prior art rather than past it.
Most claims are written at the paper level
Nearly four in five records in scope classify under D21H, pulp and paper compositions, rather than under a device-specific class. That means the contested claim space is the sheet's own fibre blend, density and grammage, not the motor or transformer it ends up in.
No new filing wave has emerged
The filing trend peaked at 7 records in 2017 and had dropped to 0 by 2022, with the years since showing no clear recovery before the cut-off. That pattern points to an occupied claim space rather than an actively contested one.
One filer, then a long tail
The leading assignee holds 20 records against a fifth-place figure of 2 and a tenth-place figure of 1 across the 17 companies in this ranking. Everyone below the leader is filing in single or low-double digits, which is the profile of a field with one dominant patent holder and a scattered set of smaller entrants.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to aramid paper for electrical insulation, with the prior art for and against each one.
Who holds the claim space, and where it is thinnest
The assignee ranking is short and top-heavy, and none of the tracked assignees show filings in the latest year — a sign the founding players have not been actively refreshing this claim space recently.
One company holds most of the documented composition art
The top assignee's 20 records dwarf the fifth-place count of 2, putting most of the core aramid paper blend and fibrid composition claims in a single company's hands. Co-assignee pairings around this filer, including a three-strong pairing with an individual inventor, suggest continued internal collaboration rather than a joint venture with an outside firm.
Most other players hold a single filing
Below the leader and a handful of mid-tier names, the ranking drops quickly to single-digit and single-record positions. That is the profile of a niche where a would-be entrant is more likely to be filing something genuinely new than crowding an already-contested claim.
No leading assignee shows recent-year activity
Every assignee tracked for recent-year momentum, including the top filer and its most frequent co-assignees, shows zero filings in the latest year. Combined with the 2017 peak and 2022 midpoint of 0, this points to a technology whose active prosecution has slowed even among the incumbents.
| Assignee | Recent year | YoY |
|---|---|---|
| E. I. du Pont de Nemours and Company | 0 | — |
| Teijin Aramid B.V. | 0 | — |
| LEVIT MIKHAIL R | 0 | — |
| KAWKA DARIUSZ WLODZIMIERZ | 0 | — |
| ANDERSON DAVID WAYNE | 0 | — |
| DuPont Teijin Advanced Papers (Japan) Ltd. | 0 | — |
| KHAN SUBHOTOSH | 0 | — |
| Chaomeisi New Materials Co., Ltd. | 0 | — |
Where to take this from here
The data points to a field with an occupied core and a quiet recent filing record — the next step is deciding whether to file around the leader's composition claims or into one of the thinner adjacent branches.
Map your own composition against the founding claims
Before drafting, check density, grammage and para-aramid content ratios against the most-cited blend and laminate patents to see how much room remains around them.
Explore claims in EurekaWatch for a filing restart, not just a filing rate
With every tracked assignee at zero in the latest year, the more useful signal going forward is which company files first, not how many filings appear.
Track assignees in EurekaTest the under-claimed branches for freedom to operate
Recycled fibrid content and hybrid aramid-polyimide laminates show thinner coverage than the core composition space and may offer a cleaner path to a grantable claim.
Run a white space search in EurekaCommon questions on aramid paper insulation patents
One assignee leads this field with 20 records in a 17-company ranking, well ahead of the fifth-place figure of 2 and the tenth-place figure of 1. That gap means the founding composition and blend patents are concentrated in a single company's portfolio rather than spread across several large filers. Anyone entering this space should expect to design around that leader's claims first, since the rest of the ranking is a long tail of small filers rather than a set of comparable competitors.
The filing trend peaked at 7 records in 2017 and had fallen to 0 by the 2022 midpoint, with no clear rebound visible before the July 2026 data cut-off. That points to a flat or declining filing rate rather than active growth. Keep in mind that publication normally lags filing by around 18 months, so the very latest years in any such dataset will always look thinner than they eventually turn out to be, but the multi-year decline through the midpoint is not explained by lag alone.
The dominant classification is D21H, pulp and paper compositions, covering 79.5% of the 39 records in scope, confirming that most claims are written at the level of the paper's own fibre blend and formulation. B32B (layered products and laminates) and H05K (printed circuits and assemblies) each cover well over a third of records too, showing the same paper is frequently claimed as a laminate or electronics substrate rather than purely as an electrical insulator. H01B, the insulator and conductor class, covers 35.9% of records. Because a single record can carry several IPC codes, these shares add up to more than 100% and should not be summed.
US20190376237A1, filed by Teijin Aramid B.V. and published 2019-12-12, claims an aramid paper defined by a specific density range (0.20-0.65 g/cm3), grammage range (30-280 g/m2), and a composition of 10-40 wt.% aramid shortcut plus 10-90 wt.% aramid fibrid, with both components at least 70 wt.% para-aramid. A product landing inside all of those numeric ranges and compositional thresholds at once would need to design around this filing specifically. Working outside any one of the ranges, or using a fibrid or shortcut blend that falls below the 70 wt.% para-aramid threshold, is one route to avoid overlap, though a full freedom-to-operate check should also cover the older, more-cited blend and laminate patents this filing builds on.
The classification data shows composition claims (D21H) are heavily filed, but adjacent branches such as recycled fibrid content, varnish impregnation process parameters, and aramid-polyimide hybrid laminates show comparatively thinner coverage relative to the core blend claims. Given that no tracked assignee, including the market leader, shows filings in the latest year, there is also room to be the first mover on a filing that updates the core composition art rather than repeating it. Any white-space claim should still be checked against the most-cited historical patents, since several of them are broad enough to touch adjacent process and laminate work.
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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.
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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.