D21C 9/10
Bleaching
Official title: Bleaching {; Apparatus therefor}
D21C9/10 (Bleaching) appears on 1,094 US grants and 801 published applications in this corpus.
Search patents in D21C- Granted patents
- 1,094
- Published applications
- 801
- Assignees
- 477
- Inventors
- 2,040
- Latest grant
- 8 Sep 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 22 | 0 |
| 1977 | 14 | 0 |
| 1978 | 19 | 0 |
| 1979 | 8 | 0 |
| 1980 | 13 | 0 |
| 1981 | 21 | 0 |
| 1982 | 9 | 0 |
| 1983 | 17 | 0 |
| 1984 | 16 | 0 |
| 1985 | 10 | 0 |
| 1986 | 15 | 0 |
| 1987 | 8 | 0 |
| 1988 | 16 | 0 |
| 1989 | 15 | 0 |
| 1990 | 13 | 0 |
| 1991 | 18 | 0 |
| 1992 | 26 | 0 |
| 1993 | 22 | 0 |
| 1994 | 31 | 0 |
| 1995 | 36 | 0 |
| 1996 | 31 | 0 |
| 1997 | 48 | 0 |
| 1998 | 29 | 0 |
| 1999 | 33 | 0 |
| 2000 | 42 | 0 |
| 2001 | 47 | 13 |
| 2002 | 29 | 34 |
| 2003 | 27 | 33 |
| 2004 | 32 | 38 |
| 2005 | 7 | 33 |
| 2006 | 16 | 38 |
| 2007 | 12 | 25 |
| 2008 | 10 | 24 |
| 2009 | 9 | 33 |
| 2010 | 7 | 34 |
| 2011 | 18 | 29 |
| 2012 | 26 | 28 |
| 2013 | 27 | 39 |
| 2014 | 36 | 32 |
| 2015 | 20 | 37 |
| 2016 | 16 | 32 |
| 2017 | 18 | 37 |
| 2018 | 24 | 35 |
| 2019 | 17 | 28 |
| 2020 | 26 | 36 |
| 2021 | 27 | 36 |
| 2022 | 20 | 36 |
| 2023 | 22 | 29 |
| 2024 | 28 | 26 |
| 2025 | 29 | 24 |
| 2026 | 12 | 12 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Subgroups
Granted patents
- D21C 9/16With per compounds375
- D21C 9/1026Other features in bleaching processes355
- D21C 9/147With oxygen or its allotropic modifications270
- D21C 9/12With halogens or halogen-containing compounds182
- D21C 9/1057Multistage, with compounds cited in more than one sub-group d21c9/10, d21c9/12, d21c9/16105
- D21C 9/1005Pretreatment of the pulp59
- D21C 9/1084With reducing compounds58
- D21C 9/1063With compounds not otherwise provided for46
Recent patents
- Crystalline cellulose reinforced cement8 Sep 2026US 12,729,158 B2
- Method for distributing chemicals in delignification stages of pulp bleaching process1 Sep 2026US 12,723,350 B2Andritz Inc.
- Optimization of chemical consumption in biomass delignification4 Aug 2026US 12,698,589 B2Sixring Inc.
- Approach to biomass delignification28 Jul 2026US 12,692,653 B2Sixring Inc.
- Xylanase variants14 Apr 2026US 12,600,960 B2AB Enzymes Finland Oy
- Pulp mixture6 Aug 2026US 2026/0226680 A1SöDra SkogsäGarna Ekonomisk FöRening
- Chemical wood pulp with enhanced tensile strength6 Aug 2026US 2026/0226685 A1SöDra SkogsäGarna Ekonomisk FöRening
- Maple HT-CTMP30 Jul 2026US 2026/0218449 A1Billerud Aktiebolag (publ)
- Production method of ctmp having a low extractives content23 Jul 2026US 2026/0210047 A1Billerud Aktiebolag (publ)
- Carboxymethylated lysine-based polymer and compositions comprising the same16 Jul 2026US 2026/0201119 A1BASF SE
Most cited
By later US patents
- Process for recovery of cellulose141US 5,057,334 AOrt's Inc. · 1991
- Lyocell fibers and process for their preparation138US 6,235,392 B1Weyerhaeuser Company · 2001
- Process of pulping and bleaching fibrous plant material with tert-butyl alcohol and tert-butyl peroxide128US 5,252,183 AABB Lummus Crest Inc. · 1993
- Lyocell fibers having enhanced CV properties115US 6,221,487 B1Weyerhauser Company · 2001
- Process for producing a pulp suitable for papermaking from nonwood fibrous materials101US 6,302,997 B1HurterConsult Incorporated · 2001