PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON

Introduced: September 1968

Classification Context

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

Description

D21F covers machines and methods for manufacturing paper from cellulose pulp, encompassing the complete papermaking process from pulp preparation through final product formation. This includes wet-end machinery (forming sections, pressing units, dryers), size presses, coating and calendering equipment, and associated control systems. The classification addresses both the mechanical equipment and operational methods for producing various paper grades and qualities on industrial paper machines.

Filing statistics

IPC subclass D21F 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

Related Keywords

making of CARDBOARD on paper-making machinesmaking of FIBREBOARD on paper-making machinesFOURDRINIER paper-making machinesmaking SHEET(S) of paper or boardsmaking WATER marks in papermachines for making continuous WEB(S) of paper or board

8 direct subcodes

Child Classifications

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D21F 1/00 Wet end of machines for making continuous webs of paper
D21F 11/00 Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibreboard production, on paper-making machines
D21F 13/00 Methods or apparatus for making discontinuous sheets of paper, pulpboard, or cardboard, or of wet web, for fibreboard production
D21F 2/00 Transferring continuous webs from wet ends to press sections
D21F 3/00 Press section of machines for making continuous webs of paper
D21F 5/00 Dryer section of machines for making continuous webs of paper
D21F 7/00 Other details of machines for making continuous webs of paper
D21F 9/00 Complete machines for making continuous webs of paper

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