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IPC Main Group
D21H 23/00

Processes or apparatus for adding material to the pulp or to the paper

Introduced: January 1990

Last revised: January 2006

Classification Context

Section:
TEXTILES; PAPER
Class:
PAPER-MAKING; PRODUCTION OF CELLULOSE
Subclass:
PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES ,; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS OR SUBCLASS; PAPER NOT OTHERWISE PROVIDED FOR

Filing statistics

IPC D21H 23/00 belongs to the parent subclass D21H, which recorded 58,363 patent applications worldwide between 2013 and 2023. Annual filings grew from 4,545 in 2013 to 4,949 in 2023 (+9%), peaking at 6,006 applications in 2020. The most active applicants in class D21 are VOITH PATENT (1,809 applications), STORA ENSO (1,467 applications) and KEMIRA (1,086 applications).

Source: EPO PATSTAT, worldwide filings

Related Keywords

IMPREGNATING of webs on paper-making machinesprocesses for adding substances to the web on the paper-making machineSIZING of pulp or webs on paper-making machines

3 direct subcodes

Child Classifications

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  • D21H 23/76 characterised by choice of auxiliary compounds which are added separately from at least one other compound, e.g. to improve the incorporation of the latter or to obtain an enhanced combined effect
  • D21H 23/78 Controlling or regulating not limited to any particular process or apparatus

Top Applicants

Top 10 applicants by patent filingsfor class D21, 2013–2023, worldwide · Source: EPO PATSTAT

  1. VOITH PATENT DE 1,809
  2. STORA ENSO FI 1,467
  3. KEMIRA FI 1,086
  4. KIMBERLY-CLARK CORPORATION US 935
  5. VALMET TECHNOLOGIES FI 924
  6. VALMET SE 904
  7. P&G (PROCTER & GAMBLE COMPANY) US 862
  8. OJI HOLDINGS CORPORATION 696
  9. OMYA INTERNATIONAL CH 584
  10. SOUTH CHINA UNIVERSITY OF TECHNOLOGY 571