D21C 3/22
Pulping cellulose-containing materials: other features of pulping processes
Official title: Other features of pulping processes
D21C3/22 (Pulping cellulose-containing materials: other features of pulping processes) appears on 565 US grants and 484 published applications in this corpus.
Search patents in D21C- Granted patents
- 565
- Published applications
- 484
- Assignees
- 302
- Inventors
- 1,017
- Latest grant
- 4 Aug 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 5 | 0 |
| 1977 | 6 | 0 |
| 1978 | 11 | 0 |
| 1979 | 9 | 0 |
| 1980 | 9 | 0 |
| 1981 | 5 | 0 |
| 1982 | 8 | 0 |
| 1983 | 4 | 0 |
| 1984 | 5 | 0 |
| 1985 | 3 | 0 |
| 1986 | 7 | 0 |
| 1987 | 7 | 0 |
| 1988 | 9 | 0 |
| 1989 | 8 | 0 |
| 1990 | 7 | 0 |
| 1991 | 6 | 0 |
| 1992 | 4 | 0 |
| 1993 | 8 | 0 |
| 1994 | 8 | 0 |
| 1995 | 9 | 0 |
| 1996 | 13 | 0 |
| 1997 | 18 | 0 |
| 1998 | 13 | 0 |
| 1999 | 12 | 0 |
| 2000 | 24 | 0 |
| 2001 | 14 | 5 |
| 2002 | 13 | 12 |
| 2003 | 8 | 11 |
| 2004 | 5 | 17 |
| 2005 | 7 | 19 |
| 2006 | 5 | 14 |
| 2007 | 13 | 14 |
| 2008 | 7 | 10 |
| 2009 | 11 | 19 |
| 2010 | 9 | 16 |
| 2011 | 12 | 28 |
| 2012 | 8 | 19 |
| 2013 | 15 | 19 |
| 2014 | 28 | 32 |
| 2015 | 16 | 21 |
| 2016 | 14 | 30 |
| 2017 | 21 | 27 |
| 2018 | 14 | 15 |
| 2019 | 12 | 21 |
| 2020 | 13 | 21 |
| 2021 | 18 | 20 |
| 2022 | 11 | 26 |
| 2023 | 13 | 20 |
| 2024 | 22 | 22 |
| 2025 | 27 | 18 |
| 2026 | 11 | 8 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Subgroups
Granted patents
- D21C 3/222Use of compounds accelerating the pulping processes157
- D21C 3/24Continuous processes148
- D21C 3/26Multistage processes99
- D21C 3/228Automation of the pulping processes33
- D21C 3/28Prevention of foam31
- D21C 3/226Use of compounds avoiding scale formation29
- D21C 3/224Use of means other than pressure and temperature24
Recent patents
- Optimization of chemical consumption in biomass delignification4 Aug 2026US 12,698,589 B2Sixring Inc.
- Processes for fractionation of biomass4 Aug 2026US 12,698,590 B2The Board of Trustees of The University of Alabama
- Process and system for producing pulp, energy, and bioderivatives from plant-based and recycled materials14 Jul 2026US 12,678,759 B2Circ, LLC
- Process for treatment of biomass for pulping and biorefinery applications19 May 2026US 12,630,975 B2Fuma Labs Private Limited
- Extraction of delignified, cellulose-based fibers from natural plant material, and materials incorporating such fibers12 May 2026US 12,624,500 B2University of Maryland, College Park
- Process and System for Producing Pulp, Energy, and Bioderivatives from Plant-Based and Recycled Materials10 Sep 2026US 2026/0264040 A1Circ, LLC
- Method of Preparing High-Strength, High-Toughness, and Recyclable Fiberboard with Bionic Structure3 Sep 2026US 2026/0258602 A1Northeast Forestry University
- Chemical wood pulp with enhanced tensile strength6 Aug 2026US 2026/0226685 A1SöDra SkogsäGarna Ekonomisk FöRening
- Two-step impregnation in ht-ctmp production23 Jul 2026US 2026/0210040 A1Billerud Aktiebolag (publ)
- Recycling of release liner glassine and sck into high quality pulp23 Jul 2026US 2026/0210041 A1Upm-Kymmene Corporation
Most cited
By later US patents
- Method of treating lignocellulosic biomass to produce cellulose109US 6,419,788 B1PureVision Technology, Inc. · 2002
- Process for oxygen pulping of lignocellulosic material and recorvery of pulping chemicals96US 6,770,168 B1Kiram AB · 2004
- Cellulose production from lignocellulosic biomass93US 6,620,292 B2PureVision Technology, Inc. · 2003
- Production of pulp by the soda-anthraquinone process (SAP) with recovery of the cooking chemicals77US 5,595,628 AGrant S.A. · 1997
- System and method for preextraction of hemicellulose through using a continuous prehydrolysis and steam explosion pretreatment process51US 8,057,639 B2Andritz Inc. · 2011