D21
Paper-making
Official title: Paper-making; production of cellulose
D21 (Paper-making) appears on 26,902 US grants and 19,535 published applications in this corpus.
Search patents in D21- Granted patents
- 26,902
- Published applications
- 19,535
- Assignees
- 6,312
- Inventors
- 36,792
- Latest grant
- 6 Oct 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 408 | 0 |
| 1977 | 331 | 0 |
| 1978 | 386 | 0 |
| 1979 | 281 | 0 |
| 1980 | 395 | 0 |
| 1981 | 413 | 0 |
| 1982 | 332 | 0 |
| 1983 | 380 | 0 |
| 1984 | 445 | 0 |
| 1985 | 466 | 0 |
| 1986 | 366 | 0 |
| 1987 | 412 | 0 |
| 1988 | 430 | 0 |
| 1989 | 487 | 0 |
| 1990 | 541 | 0 |
| 1991 | 528 | 0 |
| 1992 | 602 | 0 |
| 1993 | 537 | 0 |
| 1994 | 501 | 0 |
| 1995 | 585 | 0 |
| 1996 | 660 | 0 |
| 1997 | 746 | 0 |
| 1998 | 791 | 0 |
| 1999 | 784 | 0 |
| 2000 | 782 | 0 |
| 2001 | 886 | 210 |
| 2002 | 797 | 705 |
| 2003 | 653 | 873 |
| 2004 | 575 | 953 |
| 2005 | 414 | 823 |
| 2006 | 438 | 786 |
| 2007 | 402 | 774 |
| 2008 | 351 | 766 |
| 2009 | 357 | 732 |
| 2010 | 511 | 863 |
| 2011 | 558 | 699 |
| 2012 | 565 | 723 |
| 2013 | 589 | 763 |
| 2014 | 633 | 757 |
| 2015 | 529 | 886 |
| 2016 | 561 | 822 |
| 2017 | 587 | 755 |
| 2018 | 572 | 709 |
| 2019 | 578 | 754 |
| 2020 | 605 | 785 |
| 2021 | 587 | 771 |
| 2022 | 546 | 775 |
| 2023 | 535 | 783 |
| 2024 | 579 | 822 |
| 2025 | 535 | 679 |
| 2026 | 370 | 567 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Subclasses
Granted patents
- D21HPulp compositions13,701
- D21FPaper-making machines7,069
- D21CProduction of cellulose by removing non-cellulose substances from cellulose-containing materials5,188
- D21GCalenders2,288
- D21BFibrous raw materials or their mechanical treatment1,584
- D21DTreatment of the materials before passing to the paper-making machine1,557
- D21JFibreboard653
Recent patents
- Fibrous body processing apparatus6 Oct 2026US 12,753,550 B2Seiko Epson Corporation
- Method for fractionation of highly refined cellulose6 Oct 2026US 12,753,551 B2Stora Enso OYJ
- Web material structuring belt comprising a seam and method for making and using6 Oct 2026US 12,753,552 B2The Procter & Gamble Company
- Low cellulosic non-wood fiber products and methods of making the same6 Oct 2026US 12,753,553 B2Archer Daniels Midland Company
- Corrugated board for humid conditions6 Oct 2026US 12,753,554 B2Billerud Aktiebolag (publ)
- Sublimation printing transfer paper having tacky properties8 Oct 2026US 2026/0307415 A1
- Arrays of sanitary tissue products comprising non-wood(s)8 Oct 2026US 2026/0307891 A1The Procter & Gamble Company
- Synthetic wax materials with degradable linkers8 Oct 2026US 2026/0308317 A1Board of Trustees of Michigan State University
- Industrial fabric with laser induced structures8 Oct 2026US 2026/0308838 A1AstenJohnson International, Inc.
- Biomass processing system for treatment of biomass material8 Oct 2026US 2026/0308845 A1Valmet Corporation
Most cited
By later US patents
- End use applications of biodegradable polymers1,525US 5,444,113 AEcopol, LLC · 1995
- Process for making unitary fibrous structure comprising randomly distributed cellulosic fibers and non-randomly distributed synthetic fibers1,408US 7,067,038 B2The Procter & Gamble Company · 2006
- Method for making a fibrous structure comprising cellulosic and synthetic fibers1,393US 7,354,502 B2The Procter & Gamble Company · 2008
- Diaper having a lotioned topsheet815US 5,643,588 AThe Procter & Gamble Company · 1997
- Hesperaloe tissue having improved cross-machine direction properties809US 10,337,148 B2Kimberly-Clark Worldwide, Inc. · 2019