CPC Main Group
D21C 3/00 Pulping cellulose-containing materials (digesters D21C7/00)
7 direct subcodes
Child Classifications
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- D21C 3/02 with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
- D21C 3/04 with acids, acid salts or acid anhydrides
- D21C 3/18 with halogens or halogen-generating compounds (bleaching cellulose pulp D21C9/12)
- D21C 3/20 with organic solvents
- D21C 3/22 Other features of pulping processes
Top Applicants
Top 10 applicants by patent filingsfor class D21, 2013–2023, worldwide · Source: EPO PATSTAT
- VOITH PATENT DE 1,857
- STORA ENSO FI 1,552
- KEMIRA FI 1,173
- KIMBERLY-CLARK CORPORATION US 1,107
- VALMET TECHNOLOGIES FI 965
- VALMET SE 943
- P&G (PROCTER & GAMBLE COMPANY) US 941
- OMYA INTERNATIONAL CH 821
- UPM-KYMMENE CORPORATION FI 512
- SEIKO EPSON CORPORATION JP 501