Retention and Drainage Aid Patents: Who Leads, White Space 2026
- 32.3% concentration at the top. The five leading assignees combine for 1,555 of the 4,815 records in scope — a field where a handful of specialty-chemical suppliers hold a third of the documented filings.
- Filing has cooled from its 2019 peak. Annual filings ran from 150 at the 2019 peak down to a measured -29% between 2021 (17) and 2024 (12), the last year publication lag lets us treat as complete.
- D21H dominates, but the supporting chemistry is fragmented. 77.2% of records sit in pulp-and-paper compositions (D21H), while colloidal-silica-adjacent inorganic chemistry (C01B, 12.9%) and separation processes (B01D, 5.0%) remain comparatively thin.
Filing growth compares 2021 (17 records) with 2024 (12) — 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 4,815 records in scope (CR5), not by the ranked leaders only.
What retention and drainage aid patenting actually covers
Retention and drainage aid programs sit at the intersection of papermaking process chemistry and colloid science: polymers, microparticles and inorganic additives that hold fibre and fines on the wire while water drains fast enough to keep a paper machine running at speed. The patent record spans first-pass retention chemistry, colloidal silica and bentonite microparticle systems, and the machine-side compromises between formation quality and drainage rate that show up as claim language around shear stages and white-water consistency.
The dataset behind this page covers 4,815 published records filed between 2015 and mid-2026, drawn from a search built around first-pass retention, microparticle and colloidal-silica claim language. Because publication lags filing by roughly 18 months, the most recent one to two years understate true filing activity and should be read as provisional.
Filing trends and technology composition
Two views of the same 4,815-record set: how filing volume has moved year over year, and how those records distribute across IPC subclasses. Because a single record can carry several IPC codes, the class shares below add up to more than 100% of the record total.
Filing trend, 2017–2026
Annual filings ran from 144 in 2017 to a peak of 150 in 2019, then eased to 12 by 2024 — a -29% move from 2021's 17 filings, the clearest complete-year comparison available. 2025 and 2026 figures are still filling in under normal publication lag and should not be read as a continued decline.
IPC subclass composition
D21H (pulp and paper compositions) anchors the field at 77.2% of records. C01B inorganic chemistry (12.9%), C08F addition polymers (9.5%) and C08L polymer compositions (7.6%) supply the retention-active ingredients, while D21F machine claims (5.8%), B01D separation (5.0%), B01J catalytic processes (4.9%) and B41M printing/marking (4.7%) mark the smaller adjacent branches.
Shares are the percentage of the 4,815 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Retention and Drainage Aid Programs with Eureka
This page is one run against one query. Ask Eureka your own question about retention and drainage aid programs and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative and most-cited filings
US20050269050A1 — High performance natural zeolite microparticle retention aid for papermaking
A microparticle retention aid for use in papermaking containing a high performance purified natural zeolite pigment is disclosed. Use of the pigment facilitates manufacture of papers with improved quality and economics. When used as filler, the novel zeolite pigment is readily retained and eliminates print-through in uncoated papers. The novel zeolite pigment is low in abrasion and provides improved coefficient of friction.Filed by ZO Mineral Partners, this record is representative of a mineral-substitution approach to microparticle retention that sits alongside the more heavily filed silica and bentonite routes.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US10106932B2 | Substrate for wallboard joint tape and process for making same | 790 |
| 2 | US4753710A | Production of paper and paperboard | 469 |
| 3 | US5176891A | Polyaluminosilicate process | 381 |
| 4 | US4913775A | Production of paper and paper board | 325 |
| 5 | US6379497B1 | Bulk enhanced paperboard and shaped products made therefrom | 320 |
| 6 | US5709976A | Coated papers | 293 |
| 7 | US4954220A | Polysilicate microgels as retention/drainage aids in papermaking | 285 |
| 8 | US5611890A | Tissue paper containing a fine particulate filler | 261 |
| 9 | EP0235893A1 | Production of paper and paperboard | 258 |
| 10 | US6740373B1 | Coated paperboards and paperboard containers having improved tactile and bulk insulation properties | 230 |
Citation counts favour older filings in any searched corpus and should be read as a signal of influence rather than current relevance — several of the most-cited records here predate the 2015 filing window and are included for citation context.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Read together, the concentration figures and the IPC composition point to a field where the core chemistry is well claimed but the supporting process and mineral-substitution branches are not.
The core chemistry is locked up by a small group
Five assignees account for 1,555 of the 4,815 records in scope, and the top ten reach exactly half the field at 2,408 records. That is a dense core around polymer and microparticle retention systems where a new entrant should expect prior art on almost any straightforward claim combination.
Volume has come down from its 2019 peak
Filings peaked at 150 in 2019 and, on the last fully comparable stretch, fell from 17 in 2021 to 12 in 2024. That is a real cooling in the segment tracked by this search string, not a sign the underlying process problem is solved — formation-versus-drainage tradeoffs are still an open engineering question.
Pulp-and-paper composition claims crowd the centre
D21H covers more than three-quarters of the 4,815 records, meaning most filings still claim through the core paper-chemistry composition route rather than through machine-side (D21F, 5.8%) or separation-process (B01D, 5.0%) angles, which remain comparatively open.
Filing offices favour US, EPO and Canada
The United States leads receiving offices at 917 records, ahead of the EPO at 788 and Canada at 477, with WIPO PCT filings at 368. That spread suggests most applicants still pursue direct national or regional protection in North America and Europe ahead of, or alongside, a PCT route.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to retention and drainage aid programs, with the prior art for and against each one.
| Assignee | Co-assignee | Shared families |
|---|---|---|
| Akzo Nobel N.V. | Akzo Nobel Chemicals (AkzoNobel Chemicals) | 78 |
| Ciba Specialty Chemicals Water Treatments Ltd | CDM Corporation | 34 |
| Nippon Paper Industries Co., Ltd. | Jujo Thermal Oy | 16 |
| Nalco Company | KEISER BRUCE A | 13 |
| Akzo Nobel N.V. | Akzo Nobel Chemicals International B.V. | 12 |
| Nalco Company | KEIZER TIMOTHY S | 12 |
| Nalco Company | ADAIR JAMES H | 12 |
| Akzo Nobel N.V. | TOKARZ MAREK | 9 |
The dataset surfaces only ten co-assignee pairs, and the strongest of these still represents a small fraction of either partner's total output — most retention and drainage aid patenting in this set is filed by a single assignee rather than jointly.
Who is filing, and where the gaps sit
The ranking covers 100 companies counted by record volume — the entire set the data endpoint returns, not a curated top tier. A leader well ahead of the pack sits atop a field that thins quickly after the tenth position.
One specialty-chemical supplier sets the pace
The leading assignee holds 459 records, more than double the fifth-place total of 211 and well ahead of the field. That gap suggests a long-running, systematic filing program around retention chemistry rather than opportunistic patenting.
The tier below the leaders is still substantial
Tenth place still holds 135 records, meaning the top 10 assignees combined reach 2,408 records, or 50.0% of the entire 4,815-record dataset. Competitive intensity does not fall off a cliff after the leader — it stays high through a second tier of established suppliers.
Recent-year activity has gone quiet across the incumbents
Several of the most historically active assignees show zero filings in the latest tracked year, including a -100% year-on-year move for one major player. Given the 18-month publication lag, this likely reflects filings still working through the pipeline rather than a genuine stop in R&D investment.
Joint filings are rare and concentrated
Only ten co-assignee pairs appear in the dataset, with the strongest pairing well ahead of the others. Most competitors in this field patent independently, which means licensing and cross-filing arrangements are the exception rather than the norm.
| Assignee | Recent year | YoY |
|---|---|---|
| Akzo Nobel N.V. | 0 | — |
| Ciba Specialty Chemicals Water Treatments Ltd | 0 | — |
| Kemira Oyj | 0 | -100% |
| Nalco Company | 0 | — |
| BASF SE | 0 | — |
| Hercules Inc. | 0 | — |
| E.I. du Pont de Nemours & Co. | 0 | — |
| Nippon Paper Industries Co., Ltd. | 0 | — |
Turning this landscape into a filing or sourcing decision
The figures above describe where the field stands; the next step is testing a specific claim idea or shortlist of targets against the full record set.
Stress-test a claim against the dense core
Before drafting around first-pass retention or colloidal-silica microparticle chemistry, check the specific claim language against the assignees holding the top concentration in this dataset.
Explore the full dataset in EurekaScout the under-claimed branches
Shear-stage process claims and mineral-substitute microparticle systems show thinner IPC coverage than the D21H core — worth a closer prior-art pass before committing R&D spend.
Run a white-space search in EurekaTrack momentum, not just headcount
Several long-standing leaders show zero filings in the latest tracked year; distinguishing publication lag from genuine pullback matters for competitive monitoring.
Set up assignee monitoring in EurekaCommon questions on retention and drainage aid patents
The ranked leader holds 459 records in this dataset, more than double the fifth-place assignee's 211. The top five assignees combined account for 1,555 records, or 32.3% of the 4,815 records in scope, and the top ten reach exactly half the field at 2,408 records. That concentration is typical of specialty papermaking chemistry, where a small number of established suppliers have filed continuously for decades.
Filing peaked at 150 records in 2019 and has since eased; on the last fully comparable stretch, volume dropped from 17 filings in 2021 to 12 in 2024, a -29% move. Because publication lags filing by roughly 18 months, the 2025 and 2026 figures in any dataset are still incomplete and should not be read as confirming a continued decline. The honest read is a mature field with a real cooling trend through 2024, not an accelerating one.
Pulp and paper composition claims under IPC class D21H cover 77.2% of the 4,815 records in scope, making it by far the largest single category. Supporting chemistry classes — C01B inorganic compounds at 12.9%, C08F addition polymers at 9.5%, and C08L polymer compositions at 7.6% — round out the core retention-active ingredient space. Machine-side claims (D21F) and separation-process claims (B01D) each sit under 6% of records, marking them as comparatively open relative to the composition core.
The clearest gaps sit outside the dense D21H composition core: shear-stage process claims under D21F, colloidal-silica dosing tied to separation stages under B01D, and catalytic activation approaches under B01J all carry noticeably thinner coverage. Mineral-substitute microparticle systems, illustrated by the zeolite-based representative filing in this dataset, are another underexplored route relative to the heavily filed silica and bentonite systems. Any of these branches is a more promising place to start a freedom-to-operate check than the crowded composition claims.
Very limited — the dataset surfaces only ten co-assignee pairs across all 4,815 records, and even the strongest pairing represents a modest share of either partner's total filings. Most retention and drainage aid patents are filed by a single assignee rather than through joint ventures or co-development arrangements. That matters for licensing strategy: a prospective partner is more likely to be approached cold than found through an existing co-filing relationship.
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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.