Mica Insulation Patents: Who Leads, Where the Gaps Are 2026
- Filing has cooled from its 2017 peak. 35 records that year versus 3 in the most recent (partial) year, with the 2022 midpoint already down to 15 — a flat-to-declining trend, not a growth story.
- No single company controls the field. The leader holds 41 records out of 581, and the top 5 assignees combined account for only 19.6% of all records in scope — filing is spread across a long tail.
- China dominates where filings are made. 368 of the tracked records were filed at the Chinese receiving office, more than five times the next-largest office, Japan at 69.
What this landscape covers
This dataset tracks patent filings on mica insulation, mica tape and mica sheet insulation where the abstract or claims address corona resistance, thermal endurance, binder content, flexibility, VPI compatibility or fire-resistant cable applications. Mica-based insulation sits at the intersection of cable and conductor engineering, electric motor and generator design, and polymer chemistry, which is why the technology composition spans several distinct IPC subclasses rather than a single one.
The 581 records in scope run 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 partial figure rather than a genuine drop-off.
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Filing trend and technology composition
Two views of the same 581 records: how filing activity has moved year over year, and which technology subclasses the claims actually sit in.
Filing trend, 2017-2026
Filings peaked in 2017 at 35 records and declined to a 2022 midpoint of 15, continuing down to 3 in the most recent partial year. The pattern points to a mature, flat-to-declining filing environment rather than an emerging one, though the final year or two should be treated as undercounted given publication lag.
IPC subclass composition
H01B (cables, conductors and insulators) covers 81.6% of the 581 records, confirming that most activity is claimed as cable/conductor insulation rather than as a standalone material. H02K (motors and generators) and B32B (layered products) are the next largest at 17.2% and 9.8% respectively, with polymer-chemistry classes such as C08L, C08K, C09J and C08J each below 6% — since records can carry multiple classes, these shares sum to more than 100%.
Shares are the percentage of the 581 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Mica-Based Insulation Materials with Eureka
This page is one run against one query. Ask Eureka your own question about mica-based insulation materials and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited records and a representative filing
Fire resistant cable for medium or high voltage (WO2014081096A1)
The filing addresses a specific failure mode in mica-tape fire-resistant layers: small winding radii create curvatures and gaps that trigger partial discharge. It claims a fire-resistant layer positioned according to insulation thickness and withstand-voltage requirements so that electric field strength at that layer is kept within an optimum range, reducing gap-driven partial discharge while preserving installation convenience.Filed by LS Cable & System Ltd., published 2014-05-30.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US6359232B1 | Electrical insulating material and stator bar formed therewith | 109 |
| 2 | US4091139A | Semiconductor binding tape and an electrical member wrapped therewith | 87 |
| 3 | US4724345A | Electrodepositing mica on coil connections | 62 |
| 4 | US4704322A | Resin rich mica tape | 60 |
| 5 | US7425366B2 | Tape member or sheet member, and method of producing tape member or sheet member | 49 |
| 6 | US4622116A | Process for electrodepositing mica on coil or bar connections and resulting products | 46 |
| 7 | US4286010A | Insulating mica paper and tapes thereof | 45 |
| 8 | US20060258791A1 | Tape member or sheet member, and method of producing tape member or sheet member | 44 |
| 9 | US4606785A | Simplified method of making high strength resin bonded mica tape | 36 |
| 10 | US5079077A | Fire-resistant composite mica insulation | 35 |
Citation counts favour older records simply because they have had more time to accumulate citations within the searched corpus — treat this as a signal of influence on subsequent filings, not of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three patterns worth acting on before drafting new claims in this space.
Leadership is real but not dominant
The leading assignee holds 41 records, yet the top 5 combined reach only 19.6% of all 581 records in scope and the top 10 only 29.4%. That leaves roughly 70% of filings spread across a long tail of single- or few-filing entrants — a structure where a well-drafted claim can still carve out defensible space.
A cooling filing environment
Peak filing activity was 2017 at 35 records; by the 2022 midpoint it had already fallen to 15, and the latest partial year shows only 3. Recent-year momentum among several previously active assignees has dropped to zero, though the most recent year or two is understated by publication lag.
Filing activity is concentrated in China
China accounts for 368 of the 581 tracked records, well ahead of Japan (69), the United States (44), the EPO (27), South Korea (19) and India (9). Anyone assessing freedom-to-operate should weight Chinese prior art heavily rather than treating it as a secondary jurisdiction.
Co-filing is limited and concentrated
Only 10 co-assignee pairs appear across the dataset, with the strongest pairs each reaching 12-13 joint records. Most filers work independently rather than through joint development structures, so cross-licensing exposure from co-owned families is limited outside a handful of relationships.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to mica-based insulation materials, with the prior art for and against each one.
Who is filing, and where the openings sit
No company controls this field outright, and recent-year momentum has cooled even among assignees that led earlier years.
A leader without a lock
The top-ranked assignee holds 41 of the 581 records, well ahead of fifth place (13) and tenth place (10) — a clear leader, but not one that closes off the field.
Fragmented ownership beyond the top 10
With the top 10 combined at just 29.4% of all records, the remaining ranked assignees and unranked filers hold the majority of the field, a sign that consolidation has not happened here.
Even established filers have gone quiet
Several previously active assignees show zero filings in the latest tracked year. Combined with the overall decline from the 2017 peak, this suggests the core claim space around conventional mica tape construction is seen as largely settled.
| Assignee | Recent year | YoY |
|---|---|---|
| Toshiba Corporation | 0 | — |
| Suzhou Jufeng Metal Wire & Cable Co., Ltd. | 0 | — |
| Westinghouse Electric Corp | 0 | — |
| TE Connectivity Corp | 0 | — |
| Isovolta AG | 0 | — |
| Compagnie Royale Asturienne des Mines | 0 | — |
| Huntsman Advanced Materials Licensing (Switzerland) GmbH | 0 | — |
| LS CABLE & SYST LTD | 0 | — |
Where to take this analysis
The dataset points to specific next steps depending on whether you are drafting claims, assessing freedom-to-operate, or scouting partners.
Check the under-claimed branches
Binder chemistry, adhesive systems and flexible-sheet processing all sit at low single-digit shares of the 581 records despite overlapping the dominant H01B cluster — worth a closer prior-art pull before drafting.
Explore white space in EurekaWatch the Chinese filing base
With 368 of 581 records filed via the Chinese receiving office, a freedom-to-operate review that skips this jurisdiction will miss most of the active claim space.
Run a China-focused search in EurekaTrack momentum shifts
Several formerly active assignees now show zero recent filings. Monitoring which of the remaining long-tail filers pick up activity next can flag emerging competitive moves early.
Set up assignee alerts in EurekaCommon questions about mica insulation patents
Across the 581 records in scope, one assignee leads with 41 records, noticeably ahead of the fifth-ranked assignee at 13 and the tenth at 10. However, the top 5 assignees combined account for only 19.6% of all 581 records, and the top 10 for 29.4%, so no single company controls the field. The remaining majority of filings are spread across a long tail of smaller and single-filing entrants, which means competitive risk is distributed rather than concentrated in one or two firms.
Filing has slowed considerably since a 2017 peak of 35 records. By the 2022 midpoint activity had already dropped to 15, and the most recent tracked year shows only 3 records. Some of that recent decline reflects publication lag, since filings typically take around 18 months to publish, but the multi-year downward trend from 2017 through 2022 is a genuine signal that the field is maturing rather than expanding.
The large majority of records, 81.6% of the 581 in scope, fall under IPC subclass H01B, covering cables, conductors and insulators, which shows most patents frame mica insulation as part of a cable or conductor assembly rather than a standalone material claim. Electric motors and generators (H02K) follow at 17.2%, and layered products and laminates (B32B) at 9.8%. Polymer-chemistry-focused classes such as C08L, C08K, C09J and C08J each sit below 6%, suggesting the binder and adhesive chemistry side of the technology is comparatively less claimed.
Given the fragmented ownership structure, with the ranked top 10 assignees holding only 29.4% of the 581 records, there is room to file in specific niches rather than needing to displace an entrenched leader. The lower-share IPC classes, including adhesive systems (C09J at 3.4%) and polymer processing (C08J at 2.8%), are less densely claimed than the dominant H01B cable/conductor cluster and are worth a targeted prior-art search before drafting. Because 368 of the 581 records were filed via the Chinese receiving office, any freedom-to-operate review needs to weight Chinese filings heavily rather than treating them as secondary.
WO2014081096A1, filed by LS Cable & System, claims a fire-resistant cable design that positions the mica-tape fire-resistant layer at a location determined by insulation thickness and withstand-voltage requirements, specifically to control electric field strength and suppress partial discharge caused by winding-induced curvatures and gaps. It does not claim mica tape insulation broadly. Designs that route around the specific layer-positioning and field-strength relationship it describes, or that solve the curvature/gap problem through a different mechanism such as tape composition or winding method, are not automatically blocked by this filing.
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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.