Conversion Coating & Anodizing Patents: Trends & White Space 2026
- Filing has declined, not grown. annual filings fell from a peak of 174 in 2018 to single digits by 2026, with the midpoint year (2022, 121) already below peak — this is a maturing, not expanding, claim space.
- Coating and electroplating IPC codes dominate. C23C and C25D together account for the large majority of the 5,488 families, leaving adjacent classes like C23G (cleaning) and C22C (alloys) comparatively thin.
- No assignee is currently accelerating. every tracked assignee in the momentum data shows flat or negative year-on-year filing, including established names moving to zero — a sign the core chemistry is largely staked out.
Filing growth compares 2021 (131 records) with 2024 (94) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 5,488 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Conversion coating and anodizing patents span the chemistry and process control used to build protective or decorative oxide and conversion layers on metal surfaces — oxide layer thickness control, sealing, corrosion resistance, pretreatment and coloring are the functional claims that define this dataset. The search spans C25D11 (anodizing), C23C22 (chemical conversion coating) and C23C28 (layered coating combinations), pulling in 5,488 patent families filed since 2017.
Publication typically lags filing by around 18 months, so the sharp drop shown in the most recent year overstates the actual slowdown — some of that gap will fill in as later filings publish. Even accounting for that lag, the trend from 2018's peak through the 2022 midpoint points to a technology area past its filing high-water mark rather than one still climbing.
Filing trends and technology composition
Annual filing counts and IPC composition for the 5,488 families in this dataset, drawn from receiving offices spanning the US, Europe, Japan, China, South Korea and the WIPO PCT route.
A peak already behind us
Filings rose to 174 in 2018, then eased toward 121 by the 2022 midpoint and down to single digits by 2026 (a partial year). That shape is consistent with a technology where the core process chemistry — bath composition, sealing steps, pretreatment sequences — was claimed early and heavily, leaving later entrants to file narrower, incremental improvements rather than foundational process claims.
Coating and electroplating classes carry the weight
C23C (coating and surface deposition, 3,257 records) and C25D (electroplating and electroforming, 2,868) between them account for most of the corpus. C09D (coatings, paints and inks), B05D (coating processes) and B32B (layered products) form a secondary tier, while C23F (corrosion and metal removal), C22C (alloys) and C23G (cleaning of metal surfaces) are comparatively lightly filed — a signal for where process-adjacent claim space remains less crowded.
Shares are the percentage of the 5,488 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Conversion Coating and Anodizing with Eureka
This page is one run against one query. Ask Eureka your own question about conversion coating and anodizing and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited records and a recent representative filing
Chemical conversion coating solution, method for coloring metal element, metal element, and slide fastener
A chemical conversion coating solution containing selenium dioxide and sodium persulfate is provided, which is advantageous for forming a colored coating having excellent corrosion resistance on the surface of a metal element of a slide fastener. The solution contains SeO2, CuCl2, H2SO4, and Na2S2O8.Filed by YKK Corporation, published 2026-07-23 — illustrates how filing activity in this space now skews toward narrow, component-specific applications (here, slide fastener hardware) rather than broad process chemistry.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5104514A | Protective coating system for aluminum | 582 |
| 2 | US5292549A | Metallic coated steel having a siloxane film providing temporary corrosion protection and method therefor | 231 |
| 3 | US5449415A | Composition and process for treating metals | 222 |
| 4 | US20040103740A1 | Intelligent, self-contained robotic hand | 218 |
| 5 | US6200878B1 | SOI substrate processing method | 210 |
| 6 | US3912548A | Method for treating metal surfaces with compositions comprising zirconium and a polymer | 190 |
| 7 | US7168748B2 | Intelligent, self-contained robotic hand | 188 |
| 8 | WO2003002776A2 | Method of anodizing of magnesium and magnesium alloys and producing conductive layers on an anodized surface | 174 |
| 9 | US5584946A | Chromium-free conversion coating treatment of aluminum | 134 |
| 10 | US20040163736A1 | Pretreatment method for coating | 126 |
Citation counts reward older filings that have had more time to accumulate citations within the searched corpus — read this as a map of prior-art influence, not of what matters commercially today.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three findings shape how a team should read this dataset: where claim density sits, why the recent decline needs a caveat, and what the citation leaders tell you.
The core process chemistry looks largely staked out
A decline from a 2018 peak of 174 filings to 4 in the most recent year, with the 2022 midpoint at 121, describes a field where early entrants secured the foundational bath-chemistry and sealing-step claims. New filers are more likely to encounter dense prior art on core anodizing and conversion-coating process steps than open ground.
Two IPC subclasses carry most of the corpus
C23C and C25D together dominate the 5,488-family dataset, meaning any freedom-to-operate review has to start there. The secondary classes — C09D, B05D, B32B — are worth checking for coating-formulation angles that sit adjacent to the core process claims.
The most-cited prior art predates the current filing wave
The highest-cited record in this corpus is a protective aluminum coating system with 582 citations — a foundational reference, not a current filing. High citation counts here mark influence built up over years in a searched corpus, and should not be read as a signal of which claims are commercially active now.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to conversion coating and anodizing, with the prior art for and against each one.
| Assignee | Co-assignee | Shared families |
|---|---|---|
| Nihon Parkerizing Co., Ltd. | Denso Corporation | 18 |
| JFE Steel Corporation | JFE Steel Sheet Co., Ltd. | 18 |
| Chemetall GmbH | Alonim Agricultural Cooperative Holdings Ltd. | 17 |
| Nippon Paint Co., Ltd. | Chemetall GmbH | 15 |
| Nippon Paint Co., Ltd. | Resonac Holdings Corporation | 10 |
| Nippon Paint Co., Ltd. | Mikuni Color Ltd. | 8 |
| Chemetall GmbH | Rhodia Operations | 8 |
| Henkel Corporation (USA) | NAGASHIMA YASUHIKO | 6 |
Only 10 co-assignee pairs appear in the dataset, with the strongest pairings each sharing 17-18 co-filed families — evidence that most activity in this space is filed by single assignees rather than through joint development arrangements.
Who is active, and where momentum has stalled
Recent-year filing momentum across tracked assignees is flat or negative across the board, including firms with substantial historical portfolios — a pattern consistent with a maturing claim space rather than one where a new entrant is pulling ahead.
Several established filers show zero recent activity
More than one long-standing assignee in the momentum data recorded zero filings in the latest tracked year, with some showing a full -100% year-on-year drop. This is consistent with a corpus where the technology's core claims were filed in earlier years and current activity is concentrated in narrow follow-on work.
Joint filings are the exception, not the rule
Cross-referencing assignee pairs across the corpus turns up only 10 co-assignee relationships, the strongest sharing 17-18 families. Most filing here is done independently, which matters for anyone scanning for existing joint-development or supply relationships to approach.
Filing is spread across six major offices
The United States leads at 1,159 filings, followed by Europe (778), Japan (724), China (634), South Korea (336) and the WIPO PCT route (335). No single jurisdiction dominates the way IPC classes do, so a freedom-to-operate check needs to span at least these six offices rather than one.
| Assignee | Recent year | YoY |
|---|---|---|
| Nihon Parkerizing Co., Ltd. | 2 | -50% |
| Henkel Corporation (USA) | 0 | — |
| Henkel AG & Co. KGaA | 0 | -100% |
| Nippon Paint Co., Ltd. | 0 | — |
| The Boeing Company | 0 | — |
| Chemetall GmbH | 0 | -100% |
| Nippon Steel Corporation | 0 | -100% |
| JFE Steel Corporation | 0 | — |
Where to take this analysis
The dataset points to a maturing core with pockets of specific, narrower activity. Two directions make sense from here.
Run a freedom-to-operate check on C23C and C25D claims
Given the concentration of families in these two subclasses, any new process work in anodizing or chemical conversion coating should be checked against the dense prior art there before development spend commits to a specific bath chemistry or sealing step.
Explore the full claim set in EurekaTrack component-specific filings like the YKK slide fastener application
Recent activity skews toward narrow, application-specific claims layered on top of established process chemistry. Monitoring these can reveal where established players are still investing, even as broad process filing has slowed.
Set up monitoring in EurekaCommon questions on conversion coating and anodizing patents
The filing trend in this dataset peaked at 174 in 2018 and has fallen steadily since, with the 2022 midpoint at 121 and only a handful of filings by 2026. This pattern typically means the foundational process chemistry — bath composition, sealing steps, pretreatment sequences — was claimed heavily in earlier years, leaving less open ground for new foundational filings. Some of the apparent recent drop is also a publication-lag artefact, since patent filings typically take around 18 months to publish, so the most recent one to two years will always look thinner than they eventually turn out to be.
C23C (coating and surface deposition) and C25D (electroplating and electroforming) together account for the large majority of the 5,488 families in this corpus, making them the two classes any freedom-to-operate search must cover first. Secondary classes worth checking include C09D (coatings, paints and inks), B05D (coating processes) and B32B (layered products), which carry meaningfully fewer filings but still intersect with conversion coating claims. Lightly filed classes such as C23G (cleaning of metal surfaces) and C22C (alloys) are worth a scan too, since thinner filing density there can mean either less relevance or genuine white space.
The dataset's recent-year momentum figures show every tracked assignee at flat or negative year-on-year filing, with several dropping to zero filings in the latest year and some showing a full -100% year-on-year decline. This does not mean these companies have exited the field — many hold substantial historical portfolios — but it does mean none is currently accelerating its filing pace. A buyer or licensor evaluating this space should weight historical portfolio strength more heavily than recent filing velocity.
US20260209947A1, filed by YKK Corporation and published in mid-2026, claims a chemical conversion coating solution built around selenium dioxide, copper chloride, sulfuric acid and sodium persulfate for coloring metal elements, specifically applied to slide fastener hardware. It is a narrow, application-specific filing rather than a broad process claim, so its practical effect is limited to that composition and application rather than blocking conversion coating work generally. It is a useful example of where recent filing activity in this field is concentrated: specific chemistries applied to specific components, layered on top of already-established core process claims.
Based on IPC composition, the thinner-filed classes — C23G (cleaning of metal surfaces prior to coating), C22C (alloy-specific formulations) and C23F (corrosion and metal removal) — carry meaningfully fewer records than the dominant C23C and C25D classes. That does not guarantee open claim space, since some of that thinness may reflect classification choices rather than true novelty, but it is a reasonable starting point for scoping a narrower, defensible filing. Chromate-free sealing chemistries and alloy-specific pretreatment sequences are two specific sub-areas worth a closer prior-art search 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.