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IPC Subgroup
D21F 1/08

Regulating consistency

Introduced: September 1968

Last revised: January 2006

Full Title

Wet end of machines for making continuous webs of paper > Regulating consistency

Classification Context

Section:
TEXTILES; PAPER
Class:
PAPER-MAKING; PRODUCTION OF CELLULOSE
Subclass:
PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON

Filing statistics

IPC D21F 1/08 belongs to the parent subclass D21F, which recorded 18,833 patent applications worldwide between 2013 and 2023. Annual filings grew from 1,289 in 2013 to 1,517 in 2023 (+18%), peaking at 2,206 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

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