D21 PAPER-MAKING; PRODUCTION OF CELLULOSE
Description
This class encompasses the industrial production and processing of paper and cellulose materials, including pulping processes, bleaching, and paper manufacturing techniques. It covers machinery, methods, and apparatus used throughout the paper production chain, from raw material preparation through final paper formation and finishing. The classification includes technologies for producing various paper grades, cellulose derivatives, and related fibrous materials used in industrial and consumer applications. Adjacent classes address textile fiber production (D01) and subsequent paper converting or finishing operations not integral to the core paper-making process itself.
IPC and CPC are identically structured here. All 7 subcodes exist in both systems.
4 shared codes have differing titles between IPC and CPC.
Child Classifications
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- D21C PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR heading IPC+CPC Available in IPC and CPC
- D21D TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE heading IPC+CPC Available in IPC and CPC
- D21F PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON heading IPC+CPC Available in IPC and CPC
- D21G CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES (winders or rewinders for finished products, means for adjustment of wrinkles or lateral extensions B65H) heading IPC+CPC Available in IPC and CPC
- D21H PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR heading +3 CPC IPC+CPC Available in IPC and CPC
- D21J FIBREBOARD; MANUFACTURE OF ARTICLES FROM CELLULOSIC FIBROUS SUSPENSIONS OR FROM PAPIER-MACHE (manufacture of articles by dry processes B27N) heading IPC+CPC Available in IPC and CPC
Top Applicants
Top Applicants (IPC)
2013–2023, worldwide · Source: EPO PATSTAT
- VOITH PATENT DE 1,809
- STORA ENSO FI 1,467
- KEMIRA FI 1,086
- KIMBERLY-CLARK CORPORATION US 935
- VALMET TECHNOLOGIES FI 924
- VALMET SE 904
- P&G (PROCTER & GAMBLE COMPANY) US 862
- OJI HOLDINGS CORPORATION 696
- OMYA INTERNATIONAL CH 584
- SOUTH CHINA UNIVERSITY OF TECHNOLOGY 571
Top Applicants (CPC)
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