Nanofiltration Membrane Patents: Leaders, Trends & White Space 2026
- Filing peaked in 2021 at 15 families and has trended flat-to-down since, with 2022 at only 4 — this is not a technology in an early growth phase anymore.
- B01D dominates at 71 of 72 records while adjacent classes like C22B, H01M and C01D each carry a handful of filings — a sign of narrow, deliberate cross-filing rather than broad convergence.
- The most-cited prior art is decades old US5658460A and the composite-membrane family from the late 1990s/2000s still anchor citation counts, which tells you where foundational claims already sit.
What this landscape covers
Nanofiltration sits between ultrafiltration and reverse osmosis, and the manufacturing-process claims in this dataset concentrate on how thin-film composite layers are formed and scaled — interfacial polymerization conditions, coating steps, and post-treatment to hold flux and salt rejection steady. The search spans 72 patent families published between 2015 and mid-2026, filtered to records that explicitly discuss fabrication or scale-up rather than end-use application claims. Most activity classifies under B01D, the core separation-process subclass, with only light spillover into water treatment, metal extraction, polymer processing, coatings and battery-related IPC codes.
Publication typically lags filing by around 18 months, so the 2025-2026 count in any trend chart understates real filing activity for those years. Read the recent-year figures as a floor, not a ceiling.
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Filing trend and technology composition
Two views of the same 72-family dataset: how filing activity has moved year over year, and which IPC subclasses the claims actually sit in.
A peak in 2021, then a pullback
Filings rose from zero in 2017 to a peak of 15 in 2021, then fell back to 4 by 2022 — a midpoint that signals flat-to-declining momentum rather than sustained growth. The partial 2026 count of 1 reflects publication lag more than a real drop-off, but the multi-year decline into 2022 predates that lag effect and is a genuine signal.
Concentrated in B01D, with narrow spillover
B01D (separation processes) covers 71 of 72 records, confirming this is a tightly scoped manufacturing-process dataset rather than a broad materials-science one. Secondary classes — C02F, C22B, C08J, B05D, H01M, C01D, C01B — each appear in single digits, marking specific application contexts (water treatment, metal extraction, battery separators) where nanofiltration fabrication know-how gets cross-filed rather than areas of independent growth.
Shares are the percentage of the 72 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Nanofiltration Membrane Manufacturing Process with Eureka
This page is one run against one query. Ask Eureka your own question about nanofiltration membrane manufacturing process and every answer comes back with the patent numbers behind it.
Try EurekaA representative recent filing
WO2024254065A1 — Nanofiltration devices and systems, and related methods to convert reverse osmosis membranes to nanofiltration membranes
Nanofiltration devices and systems, along with improved methods to convert reverse osmosis membranes to nanofiltration membranes, are disclosed. Nanofiltration devices and nanofiltration systems with improved salt permeability performance are derived from incorporating controlled heating or controlled cooling of the hypochlorite solution temperature thereby producing a more consistent manufacturing process.Filed by Fluid Technology Solutions (FTS), Inc., published 2024-12-12 — one of the more recent entrants addressing RO-to-NF conversion rather than de novo thin-film composite fabrication.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5658460A | Use of inorganic ammonium cation salts to maintain the flux and salt rejection characteristics of reverse osm… | 145 |
| 2 | US6536605B2 | High performance composite membrane | 93 |
| 3 | US20020063093A1 | High performance composite membrane | 64 |
| 4 | US6132804A | High performance composite membrane | 46 |
| 5 | CN101559327A | 纳米纤维液体分离复合膜及其制备方法 | 45 |
| 6 | WO1999062623A1 | High performance composite membrane | 35 |
| 7 | US20170056840A1 | Additives for salt rejection enhancement of a membrane | 29 |
| 8 | US20170001153A1 | Nanofiltration or reverse osmosis membrane made of hard carbon film, filtering filter, two-layer-bonded-type … | 11 |
| 9 | KR1020150078245A | Hollow fiber type nanofiltration membrane having high ions removal capacity, and manufacturing method thereof | 11 |
| 10 | US20210031151A1 | Method for manufacturing high-performance thin film composite membrane through the solvent activation process | 10 |
Ranked by citation count within the searched corpus; older filings dominate because citations accumulate over time, not because they are more relevant today.
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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Three read-outs from the trend, citation and classification data that matter more than the raw counts.
The growth phase has already passed
A peak of 15 families in 2021 followed by a drop to 4 in 2022 marks this as a maturing filing area, not an emerging one. New entrants filing now are working around claims made during the 2018-2021 run-up rather than opening fresh ground.
Foundational flux-retention claims are decades old
The most-cited record in this corpus dates to the reverse-osmosis and NF membrane drying era, with the composite-membrane family from the late 1990s and early 2000s close behind. Any drying, flux-retention or coating-stability claim should be checked against this lineage first.
This is a narrow, process-specific dataset
Near-total concentration in B01D confirms the search is capturing manufacturing and separation-process claims specifically, not general membrane materials science. The single-digit spillover into C22B, H01M and C01D marks where NF fabrication technique gets reused for metal recovery and battery contexts.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to nanofiltration membrane manufacturing process, with the prior art for and against each one.
Who is active, and where the gaps sit
Recent-year momentum across the tracked assignees shows a common pattern for a maturing field: multiple established filers with zero activity in the latest year, rather than one dominant leader still pushing volume.
Several established filers have gone quiet
Assignees including Toray, BL Technologies, Koch Membrane Systems, NIMS, Evove and the Korea Research Institute of Chemical Technology all show zero filings in the latest tracked year, several with -100% YoY. That does not mean these organisations have exited the space — it means recent activity is not showing up yet in this window, consistent with publication lag, or that their claim positions are already established and they are not adding to them.
US and EPO lead receiving offices
The United States receives the largest share of filings at 19, ahead of the EPO at 10 and WIPO/PCT filings at 9. Canada, China and Israel each sit at 4, suggesting applicants are prioritising US and European protection first and using PCT or direct national filings selectively elsewhere.
Conversion-focused filings are a newer angle
Fluid Technology Solutions' 2024 filing on converting reverse osmosis membranes into nanofiltration membranes represents a distinct approach from de novo thin-film composite fabrication — repurposing existing RO manufacturing lines rather than building new NF-specific processes.
| Assignee | Recent year | YoY |
|---|---|---|
| Toray Industries, Inc. | 0 | -100% |
| BL Technologies, Inc. | 0 | — |
| Koch Membrane Systems, Inc. | 0 | — |
| National Institute for Materials Science (NIMS) | 0 | — |
| EVOVE LTD | 0 | — |
| Korea Research Institute of Chemical Technology | 0 | — |
| The Dow Chemical Company | 0 | — |
| King Abdullah University of Science and Technology (KAUST) | 0 | — |
Where to take this analysis
The trend and classification data point to specific next steps depending on whether you are scoping freedom-to-operate or looking for a filing angle.
Check the foundational citation lineage before drafting
Any claim touching drying, flux retention, or composite-layer coating stability should be checked against the decades-old prior art anchoring this corpus's citation counts before drafting new claims in that space.
Explore prior art in EurekaWatch the RO-to-NF conversion angle
With core thin-film composite fabrication claims dense and filing momentum past its 2021 peak, conversion-based approaches like WO2024254065A1 represent a comparatively less-crowded angle worth monitoring.
Track new filings in EurekaCommon questions on this landscape
Interfacial polymerization to form thin-film composite layers is the dominant manufacturing route represented in this dataset, which is why nearly all records classify under IPC subclass B01D for separation processes. The foundational patents in this space, including the high-performance composite membrane family and the flux-retention patent US5658460A, date back to the late 1990s and 2000s and remain the most-cited records in the corpus. Newer filings tend to modify specific process parameters, such as controlled heating or cooling during fabrication, rather than introducing wholly new membrane-formation chemistries.
The filing trend suggests maturing rather than growing: activity rose to a peak of 15 families in 2021 but had fallen to 4 by 2022, a decline that predates any publication-lag effect on the most recent years. This pattern, combined with several long-standing assignees showing zero filings in the latest tracked year, points to a field where core process claims are largely staked out. New entrants are more likely to find room in adjacent applications, such as RO-to-NF conversion, than in core fabrication chemistry.
This dataset tracks assignees including Toray, BL Technologies, Koch Membrane Systems, Japan's National Institute for Materials Science (NIMS), Evove, and the Korea Research Institute of Chemical Technology, among others, though several show no filings in the most recent tracked year. The most-cited individual patents in the corpus, covering high-performance composite membranes and flux-retention treatments, trace to earlier filings rather than recent activity. Anyone assessing freedom to operate should treat the citation ranking as a guide to influential prior art, not a current leaderboard.
The clearest gaps sit at the edges of the core B01D cluster: metal-ion recovery applications overlapping C22B, battery-separator-grade coatings overlapping H01M, and alkali-metal compound rejection layers overlapping C01D each show only single-digit representation in this corpus. RO-to-NF conversion methods, exemplified by a 2024 filing, are also comparatively less crowded than de novo thin-film composite fabrication. These branches are under-claimed relative to the density of the core manufacturing-process cluster, not necessarily because they are technically harder, but because filing attention has concentrated elsewhere.
US5658460A covers the use of inorganic ammonium cation salts to maintain flux and salt rejection characteristics of reverse osmosis and nanofiltration membranes during drying, and it is the most-cited record in this dataset at 145 citations. Its continued citation weight signals that drying and post-treatment steps for flux stability remain a reference point for later filings, even decades on. Anyone drafting claims around membrane drying or storage stability should review it directly, since high citation counts inside a searched corpus indicate influence on subsequent filings, not that the underlying patent is still in force everywhere.
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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.