Wet end of machines for making continuous webs of paper

Introduced: September 1968

Last revised: January 2006

Classification Context

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

Filing statistics

IPC D21F 1/00 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

20 direct subcodes

Child Classifications

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D21F 1/02 Head boxes of Fourdrinier machines
D21F 1/04 Head boxes of cylinder machines
D21F 1/06 Regulating pulp flow
D21F 1/08 Regulating consistency
D21F 1/1 Wire-cloths
D21F 1/18 Shaking-apparatus for wire-cloths and associated parts
D21F 1/24 Tilting, raising, or lowering mechanisms for wire-cloths
D21F 1/3 Protecting wire-cloths from mechanical damage
D21F 1/32 Washing wire-cloths or felts
D21F 1/34 Construction or arrangement of spraying pipes
D21F 1/36 Guiding mechanisms
D21F 1/44 Watermarking devices
D21F 1/48 Suction apparatus
D21F 1/54 Skimming devices, e.g. froth ledges
D21F 1/56 Deckle frame arrangements
D21F 1/58 Deckle straps
D21F 1/6 Cylinder moulds
D21F 1/62 Sand traps
D21F 1/64 Magnetic separators
D21F 1/66 Pulp catching, de-watering, or recovering; Re-use of pulp-water

Top Applicants

Top 10 applicants by patent filingsfor class D21, 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