Processes or apparatus for adding material to the pulp or to the paper (applying liquids or other fluent material to surfaces, in general B05; processes for making continuous lengths of paper D21F11/00)

Filing statistics

CPC D21H 23/00 belongs to the parent subclass D21H, which recorded 50,846 patent applications worldwide between 2013 and 2023. Annual filings declined from 3,964 in 2013 to 3,670 in 2023 (-7%), peaking at 5,497 applications in 2018. The most active applicants in class D21 are VOITH PATENT (1,857 applications), STORA ENSO (1,552 applications) and KEMIRA (1,173 applications).

Source: EPO PATSTAT, worldwide filings

3 direct subcodes

Child Classifications

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D21H 23/02 characterised by the manner in which substances are added
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 (D21H17/18, D21H17/70, D21H23/10 take precedence)
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

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