CPC technology class · D21

D21F - Paper-making Machines

Paper-making machines; methods of producing paper thereon. 1,255 US utility patents granted 2015–2025, with the leading assignees and year-by-year grant trajectory.

Compiled by PlainPatent · May 15, 2026

1,255
US patents granted: #3/7
in D21: 15.4%
D21 class share: +32%
5-yr velocity

The verdict

According to USPTO PatentsView, Paper-making Machines ranks #425 of 670 CPC technology areas - 1,255 US patents granted since 2015, with recorded grant volume up 32% over five years.

#425
of 670 CPC technology areas: 1,255
US patents granted, 2015–2025: Seiko Epson
leading assignee (155): +32%
grant velocity, last 5 yrs

How D21F's grant cadence moved

Between 2020–2024, D21F recorded 658 grants versus 497 in 2015–2019 (+32% equal-window velocity). Across complete years, output peaked in 2023 at 143 grants and bottomed in 2015 at 76 (+88% peak-over-trough). Lead assignee Voith Patent GmbH holds 9.1% of the class ; the top three share 19.7%.

Leaderboard read

D21F concentration, lead at 9.1%

Voith Patent GmbH leads this historical grant record at 9.1% of D21F - us corporation assignees hold 52% of class grants (413 of 800). Figures describe granted US utility patents in this CPC subclass, not current investment or legal strength.

Leader's share: 9.1%
Top three share: 19.7%
Lead over #2: 41

Where D21F sits inside D21

Among 7 subclasses in D21 (PAPER-MAKING; Production OF Cellulose), D21F ranks #3 and holds 15.4% of the parent class's 8,169 recorded grants. Sibling chips below are the other subclasses in the same parent class, not the nationwide volume/lead-share peers further down.

D21H 4,080 D21C 1,427 D21B 452 D21G 371 D21D 314 D21J 270

Rising assignees active in D21F

Company-wide grant multiples (2022–2024 vs 2019–2021) among assignees with ≥5 patents in this subclass. Growth is company-wide; class patent counts are subclass-specific.

#1 Andritz Kuesters GMBH 7.00x 1 → 7 company-wide · 6 in D21F
#2 First Quality Tissue Se, LLC 5.00x 0 → 5 company-wide · 5 in D21F
#3 Industrial Video Solutions Inc. 5.00x 0 → 5 company-wide · 5 in D21F
#4 Ichikawa Co., Ltd. 2.67x 3 → 8 company-wide · 23 in D21F
#5 Valmet AB 1.96x 22 → 43 company-wide · 11 in D21F

D21F grants by year, peak 2023 (143)

US utility-patent grants per year in D21F, 2015–2025 - recent five years are up 32% versus 2015–2019.

Voith Patent

114
Kimberly-clark…

73
Gpcp Ip Holdings

60
Stora Enso Oyj

32
First Quality Tissue

32
Albany International

25
Astenjohnson

24
Georgia-pacific…

23
Valmet Oy

23
Ichikawa

23
International Paper

22
Valmet Aktiebolag

22

What this shows Seiko Epson is the most active filer in D21F, holding 155 of the 1,255 patents in this class. Concentration at the top signals how contestable this technology area is for new entrants.

View data table

Top patent holders in CPC subclass D21F
Rank	Company	Patents in D21F
#1	Voith Patent GmbH	114
#2	Kimberly-Clark Worldwide, Inc.	73
#3	Gpcp IP Holdings LLC	60
#4	Stora Enso OYJ	32
#5	First Quality Tissue, LLC	32
#6	Albany International Corp	25
#7	Astenjohnson, Inc.	24
#8	Georgia-Pacific Consumer Products LP	23
#9	Valmet Technologies Oy	23
#10	Ichikawa Co., Ltd.	23
#11	International Paper Company	22
#12	Valmet Aktiebolag	22
#13	Structured I, LLC	21
#14	Andritz Inc.	19
#15	IBS of America	17
#16	Valmet Technologies, Inc.	16
#17	Nippon Filcon Co., Ltd.	16
#18	Valmet AB	11
#19	Stowe Woodward Licensco LLC	11
#20	Kemira OYJ	9

Footprint here vs. claim strategy

Each dot is a leading D21F assignee, placed by how many patents it holds in this class (horizontal) against its company-wide average claims per patent (vertical) - a read on whether the class is led by broad-but-shallow filers or focused deep-claim players.

Top 14 D21F assignees by class footprint. Bubble size = patents in D21F. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Classes near D21F's 1,255-grant footprint

Nationwide nearest neighbors for D21F (#425 of 670 by volume ; lead share 12.4%) - not the D21 parent-class siblings above.

Nearest by grant volume

B21K 1,246 D06N 1,265 B63C 1,244 C08C 1,240

Nearest by lead-assignee share

F42C 12.4% H01G 12.3% B60D 12.3% B42C 12.5%

Questions about D21F

Which company holds the most patents in D21F?

Seiko Epson Corporation leads D21F with 155 patents (9.1% of the subclass). By PatentsView assignee type, us corporations account for 52% of class grants.

Which D21F assignees grew fastest recently?

Among assignees with ≥5 grants in D21F, Andritz Kuesters GMBH shows the highest company-wide grant multiple (7.00x: 1 grants in 2019–2021 → 7 in 2022–2024) while holding 6 patents in this subclass. Growth is company-wide, not class-only.

How does D21F compare inside parent class D21?

Inside D21 (PAPER-MAKING; Production OF Cellulose), D21F ranks #3 of 7 subclasses by grant volume and holds 15.4% of the parent class total. The largest sibling is D21H (4,080 grants).

What to do with this data

D21F in context - here's where to go next.

Voith Patent GmbH leads D21F with 114 grants in this class. See full portfolio
D21F ranks #425 of 670 by grant volume among all tracked CPC technology areas. See the ranking
Inside parent class D21, the largest sibling subclass is D21H with 4,080 grants. Explore D21H

Figures reflect USPTO PatentsView grant data through 2026-05-15; pending applications not yet granted are not counted.

Methodology - D21F figures are USPTO PatentsView granted-utility totals for this subclass (1,255 grants in the tracked window).

Every figure on PlainPatent is rendered directly from USPTO source data, no number is typed in by an editor. This page draws directly on USPTO source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.