PlainPatent

CPC technology class · D21

D21D - Treatment OF THE Materials Before Passing TO THE Paper-ma…

Treatment of the materials before passing to the paper-making machine. 314 US utility patents granted 2015–2025, with the leading assignees and year-by-year filing trajectory.

314
US patents granted
D21
Parent CPC class
20
Active assignees
+78%
5-yr velocity

The verdict

Treatment OF THE Materials Before Passing TO THE Paper-ma… ranks #579 of 670 CPC technology areas - 314 US patents granted since 2015, with filing up 78% over five years.

#579
of 670 CPC technology areas
314
US patents granted, 2015–2025
Andritz
leading assignee (35)
+78%
filing velocity, last 5 yrs
Top assignee: Andritz Inc. (35 patents)

CPC subclass D21D - TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE - covers 314 US utility patents granted between 2015 and 2025 according to USPTO PatentsView records, within the broader CPC class D21 (PAPER-MAKING; PRODUCTION OF CELLULOSE). See our CPC classification guide for how the system works.

The competitive landscape in D21D is shaped by 20 distinct companies actively filing in this space. Andritz Inc. leads with 35 patents, followed by Valmet AB at 30 grants and Valmet Technologies Oy at 16.

Filing activity in D21D is up 78% over the past five years versus 2015-2019, a sharp acceleration suggesting an emerging or fast-moving technology area. All counts come directly from USPTO PatentsView and reflect US granted utility patents only.

Is D21D innovation accelerating?

US utility-patent grants per year in D21D, 2015–2025 - recent five years are up 78% versus 2015–2019.

1020304050 20152016201720182019202020212022202320242025 21

Who leads D21D?

The 12 most active assignees in TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE - wider bars mean more grants

patents

What this shows Andritz is the most active filer in D21D, holding 35 of the 314 patents in this class. Concentration at the top signals how contestable this technology area is for new entrants.

Source USPTO PatentsView, granted utility patents As of 2015–2025 grant years
View data table
Top patent holders in CPC subclass D21D
Rank Company Patents in D21D
#1 Andritz Inc. 35
#2 Valmet AB 30
#3 Valmet Technologies Oy 16
#4 Valmet Technologies, Inc. 13
#5 Fiberlean Technologies Limited 12
#6 Voith Patent Gmbh 10
#7 Domtar Paper Company, Llc 9
#8 International Paper Company 8
#9 Aikawa Fiber Technologies OY 5
#10 Andritz OY 4
#11 Andritz Fiedler Gmbh 4
#12 Westrock MWV, Llc 3
#13 Qilu University Of Technology 3
#14 Billerudkorsnas AB 3
#15 Suzano S.a. 3
#16 Valmet Aktiebolag 2
#17 Packaging Corporation Of America 2
#18 Mercer International Inc. 2
#19 Borregaard AS 2
#20 Kadant Black Clawson Llc 2

About This Class

CPC subclass D21D belongs to class D21.

314 patents were granted in this class between 2015 and 2025.

20 companies actively patent in this space.

Classification System

Cooperative Patent Classification (CPC) is a hierarchical patent classification system used by the USPTO and EPO.

← All Technology Classes Technology Rankings →

Footprint here vs. claim strategy

Each dot is a leading D21D 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 D21D assignees by class footprint. Bubble size = patents in D21D. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Top 14 D21D assignees by class footprint. Bubble size = patents in D21D. Source: USPTO PatentsView (claim depth is company-wide across all classes). Scatter plot of 14 data points (bubble-sized by third dimension). 510152025 010203040 Patents in D21D Avg claims / patent (company-wide) AndritzValmet AbValmet OyValmetFiberleanVoith PatentDomtar PaperInternational PaperAikawa Fiber OyAndritz OyAndritz FiedlerWestrock MwvQilu University of Te…Billerudkorsnas Ab
Top 14 D21D assignees by class footprint. Bubble size = patents in D21D. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Frequently Asked Questions

What is CPC class D21D?
CPC subclass D21D covers TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE. It belongs to CPC class D21 (PAPER-MAKING; PRODUCTION OF CELLULOSE), with 314 US utility patents granted since 2015.
How many patents have been filed in D21D?
314 US utility patents were granted in CPC subclass D21D between 2015 and 2025, based on USPTO PatentsView data.
Which company holds the most patents in D21D?
Andritz Inc. leads D21D with 35 patents, making it the most active assignee in this technology area.
How is patent data for D21D collected?
Patent data comes from USPTO PatentsView, a public research dataset maintained by the United States Patent and Trademark Office. It covers all US granted utility patents and assigns CPC codes based on the technology described in each patent.
What is the difference between CPC class and subclass?
A CPC class (e.g., D21) is a broad technology category. Subclasses like D21D provide finer granularity within that category. PlainPatent organizes data at the subclass level (4-character codes) for the most useful view of technology domains.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from USPTO PatentsView - official U.S. government patent data. See our methodology for computation details. Retrieved and formatted by PlainPatent Editorial

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.