D21C
Production of cellulose by removing non-cellulose substances from cellulose-containing materials
Official title: Production of cellulose by removing non-cellulose substances from cellulose-containing materials; regeneration of pulping liquors; apparatus therefor
D21C (Production of cellulose by removing non-cellulose substances from cellulose-containing materials) appears on 5,188 US grants and 4,032 published applications in this corpus.
Search patents in D21C- Granted patents
- 5,188
- Published applications
- 4,032
- Assignees
- 1,862
- Inventors
- 8,774
- Latest grant
- 6 Oct 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 61 | 0 |
| 1977 | 62 | 0 |
| 1978 | 76 | 0 |
| 1979 | 50 | 0 |
| 1980 | 68 | 0 |
| 1981 | 72 | 0 |
| 1982 | 50 | 0 |
| 1983 | 55 | 0 |
| 1984 | 74 | 0 |
| 1985 | 65 | 0 |
| 1986 | 57 | 0 |
| 1987 | 54 | 0 |
| 1988 | 75 | 0 |
| 1989 | 76 | 0 |
| 1990 | 81 | 0 |
| 1991 | 85 | 0 |
| 1992 | 90 | 0 |
| 1993 | 98 | 0 |
| 1994 | 111 | 0 |
| 1995 | 129 | 0 |
| 1996 | 136 | 0 |
| 1997 | 181 | 0 |
| 1998 | 170 | 0 |
| 1999 | 156 | 0 |
| 2000 | 161 | 0 |
| 2001 | 180 | 44 |
| 2002 | 137 | 145 |
| 2003 | 119 | 149 |
| 2004 | 79 | 147 |
| 2005 | 49 | 146 |
| 2006 | 65 | 123 |
| 2007 | 81 | 97 |
| 2008 | 50 | 130 |
| 2009 | 51 | 136 |
| 2010 | 71 | 174 |
| 2011 | 102 | 164 |
| 2012 | 110 | 179 |
| 2013 | 124 | 176 |
| 2014 | 177 | 222 |
| 2015 | 136 | 219 |
| 2016 | 134 | 194 |
| 2017 | 139 | 198 |
| 2018 | 131 | 158 |
| 2019 | 144 | 176 |
| 2020 | 131 | 178 |
| 2021 | 143 | 195 |
| 2022 | 109 | 170 |
| 2023 | 102 | 155 |
| 2024 | 139 | 142 |
| 2025 | 129 | 130 |
| 2026 | 63 | 85 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Main groups
Granted patents with any code in the group
- D21C 9/00After-treatment of cellulose pulp2,450
- D21C 5/00Production of cellulose by removing non-cellulose substances from cellulose-containing materials: other processes1,364
- D21C 11/00Regeneration of pulp liquors or effluent waste waters1,189
- D21C 3/00Pulping cellulose-containing materials1,111
- D21C 1/00Pretreatment of the finely-divided materials before digesting530
- D21C 7/00Digesters495
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
- Moisture/oil resistant composite materials29 Sep 2026US 12,747,536 B2World Centric
- Multi-ply liner with washed NSSC pulp29 Sep 2026US 12,747,539 B2Stora Enso OYJ
- Method for producing a transfer mixture by the direct dissolution process, using a thin layer evaporator15 Sep 2026US 12,735,840 B2List Technology AG
- Biomass processing system for treatment of biomass material8 Oct 2026US 2026/0308845 A1Valmet Corporation
- Process for producing hygienized pulp8 Oct 2026US 2026/0308846 A1Kemira Oyj
- Screw housing and plug screw feeder1 Oct 2026US 2026/0297847 A1Valmet Corporation
- System and method for controlling the cleaning of a feeder housing in a high-pressure feeder24 Sep 2026US 2026/0286606 A1Valmet Corporation
- Discharge screw arrangement24 Sep 2026US 2026/0286607 A1Valmet Corporation
Most cited
By later US patents
- Hesperaloe tissue having improved cross-machine direction properties809US 10,337,148 B2Kimberly-Clark Worldwide, Inc. · 2019
- Absorbent structure containing individualized, polycarboxylic acid crosslinked wood pulp cellulose fibers694US 5,137,537 AThe Procter & Gamble Cellulose Company · 1992
- Individualized cellulosic fibers crosslinked with polyacrylic acid polymers185US 5,549,791 AThe Procter & Gamble Company · 1996
- Process for preparing individualized, polycarboxylic acid crosslinked fibers178US 5,190,563 AThe Proctor & Gamble Company · 1993
- Method for increasing the accessibility of cellulose in lignocellulosic materials, particularly hardwoods agricultural residues and the like177US 4,461,648 A1984