D21C 3/06
Sulfur dioxide
Official title: sulfur dioxide; sulfurous acid; bisulfites {sulfites}
D21C3/06 (Sulfur dioxide) appears on 87 US grants and 116 published applications in this corpus.
Search patents in D21C- Granted patents
- 87
- Published applications
- 116
- Assignees
- 61
- Inventors
- 195
- Latest grant
- 4 Aug 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1978 | 1 | 0 |
| 1979 | 1 | 0 |
| 1980 | 1 | 0 |
| 1981 | 2 | 0 |
| 1982 | 0 | 0 |
| 1983 | 1 | 0 |
| 1984 | 1 | 0 |
| 1985 | 0 | 0 |
| 1986 | 0 | 0 |
| 1987 | 1 | 0 |
| 1988 | 3 | 0 |
| 1989 | 0 | 0 |
| 1990 | 0 | 0 |
| 1991 | 2 | 0 |
| 1992 | 0 | 0 |
| 1993 | 0 | 0 |
| 1994 | 1 | 0 |
| 1995 | 0 | 0 |
| 1996 | 0 | 0 |
| 1997 | 0 | 0 |
| 1998 | 0 | 0 |
| 1999 | 0 | 0 |
| 2000 | 0 | 0 |
| 2001 | 1 | 1 |
| 2002 | 0 | 3 |
| 2003 | 2 | 1 |
| 2004 | 0 | 1 |
| 2005 | 1 | 3 |
| 2006 | 0 | 1 |
| 2007 | 2 | 0 |
| 2008 | 1 | 1 |
| 2009 | 0 | 2 |
| 2010 | 1 | 3 |
| 2011 | 1 | 5 |
| 2012 | 3 | 4 |
| 2013 | 1 | 2 |
| 2014 | 6 | 14 |
| 2015 | 3 | 5 |
| 2016 | 6 | 9 |
| 2017 | 5 | 4 |
| 2018 | 2 | 5 |
| 2019 | 1 | 5 |
| 2020 | 2 | 3 |
| 2021 | 6 | 13 |
| 2022 | 4 | 10 |
| 2023 | 5 | 8 |
| 2024 | 9 | 3 |
| 2025 | 8 | 8 |
| 2026 | 3 | 2 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Subgroups
Granted patents
Recent patents
- Optimization of chemical consumption in biomass delignification4 Aug 2026US 12,698,589 B2Sixring Inc.
- High yield cooking method14 Apr 2026US 12,601,114 B2AMPPC Finland Oy
- Method to treat a condensate in a pulping process13 Jan 2026US 12,522,979 B2Nikede Comercio E RepresentaçõEs Ltda.
- Method for co-producing molded food-container pulp and fulvic acid from cotton stalk16 Dec 2025US 12,497,734 B2
- Cooking method21 Oct 2025US 12,448,731 B2AMPPC Finland Oy
- Method and system for treating biomass material6 Aug 2026US 2026/0226397 A1Valmet Corporation
- High-bulk ctmp23 Jul 2026US 2026/0210046 A1Billerud Aktiebolag (publ)
- Processes and apparatus for producing nanocellulose, and compositions and products produced therefrom6 Nov 2025US 2025/0340673 A1GranBio Intellectual Property Holdings, LLC
- Method for making fibres11 Sep 2025US 2025/0283255 A1
- Modified alkanesulfonic acid and uses thereof28 Aug 2025US 2025/0270760 A1
Most cited
By later US patents
- Method for the production of fermentable sugars and cellulose from lignocellulosic material33US 8,030,039 B1American Process, Inc. · 2011
- Process for making high-strength, high-yield sulfite-modified thermomechanical pulp and a linerboard composition produced therefrom29US 4,145,246 ACrown Zellerbach Corporation · 1979
- Pulping process26US 4,259,147 ANew Fibers International · 1981
- Chemithermomechanical pulping process employing separate alkali and sulfite treatments22US 4,486,267 AThe Mead Corporation · 1984
- Hardwood pulp having a tactile sense of softness, and tissue paper webs thereof20US 4,734,162 AThe Procter & Gamble Company · 1988