CPC technology class · B28

B28C - Preparing Clay

Preparing clay; producing mixtures containing clay or cementitious material, e.g. plaster. 511 US utility patents granted 2015–2025, with the leading assignees and year-by-year grant trajectory.

Compiled by PlainPatent · May 15, 2026

511
US patents granted: #3/3
in B28: 9.9%
B28 class share: +42%
5-yr velocity

The verdict

According to USPTO PatentsView, Preparing Clay ranks #540 of 670 CPC technology areas - 511 US patents granted since 2015, with recorded grant volume up 42% over five years.

#540
of 670 CPC technology areas: 511
US patents granted, 2015–2025: Oshkosh
leading assignee (50): +42%
grant velocity, last 5 yrs

How B28C's grant cadence moved

Between 2020–2024, B28C recorded 262 grants versus 185 in 2015–2019 (+42% equal-window velocity). Across complete years, output peaked in 2024 at 61 grants and bottomed in 2015 at 24 (+154% peak-over-trough). Lead assignee Oshkosh Corporation holds 9.8% of the class ; the top three share 17.2%.

Leaderboard read

B28C concentration, lead at 9.8%

Oshkosh Corporation leads this historical grant record at 9.8% of B28C - us corporation assignees hold 71% of class grants (176 of 249). Figures describe granted US utility patents in this CPC subclass, not current investment or legal strength.

Leader's share: 9.8%
Top three share: 17.2%
Lead over #2: 31

Where B28C sits inside B28

Among 3 subclasses in B28 (Working Cement, Clay, OR Stone), B28C ranks #3 and holds 9.9% of the parent class's 5,141 recorded grants. Sibling chips below are the other subclasses in the same parent class, not the nationwide volume/lead-share peers further down.

B28B 3,309 B28D 1,321

Rising assignees active in B28C

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 Oshkosh Corporation 2.23x 130 → 290 company-wide · 50 in B28C
#2 Verifi LLC 1.50x 4 → 6 company-wide · 16 in B28C
#3 Yoshino Gypsum Co., Ltd. 1.42x 12 → 17 company-wide · 6 in B28C
#4 En-tech Corporation 1.40x 5 → 7 company-wide · 9 in B28C
#5 Alkon Corporation 1.33x 6 → 8 company-wide · 13 in B28C

B28C grants by year, peak 2024 (61)

US utility-patent grants per year in B28C, 2015–2025 - recent five years are up 42% versus 2015–2019.

Oshkosh

50
United States Gypsum

19
Carboncure

19
Verifi

16
Alkon

13
Gcp Applied

9
En-tech

9
Kyb

8
Quipip

8
Cifa S P A

7
Con-tech Manufacturing

7
Sebastos

7

What this shows Oshkosh is the most active filer in B28C, holding 50 of the 511 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 B28C
Rank	Company	Patents in B28C
#1	Oshkosh Corporation	50
#2	United States Gypsum Company	19
#3	Carboncure Technologies Inc.	19
#4	Verifi LLC	16
#5	Alkon Corporation	13
#6	GCP Applied Technologies Inc.	9
#7	En-tech Corporation	9
#8	KYB Corporation	8
#9	Quipip, LLC	8
#10	Cifa S.P.A.	7
#11	Con-Tech Manufacturing, Inc.	7
#12	Sebastos Technologies, Inc.	7
#13	Yoshino Gypsum Co., Ltd.	6
#14	Giatec Scientific Inc.	5
#15	Bautex Systems, LLC	5
#16	Icon Technology, Inc.	4
#17	J&P Invesco LLC	4
#18	Concrete Products Group LLC	4
#19	U.S. Well Services, LLC	3
#20	Kangwon National University University-Industry Cooperation Foundation	3

Footprint here vs. claim strategy

Each dot is a leading B28C 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 B28C assignees by class footprint. Bubble size = patents in B28C. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Classes near B28C's 511-grant footprint

Nationwide nearest neighbors for B28C (#540 of 670 by volume ; lead share 9.8%) - not the B28 parent-class siblings above.

Nearest by grant volume

C05B 513 B61K 506 C12C 506 F23Q 516

Nearest by lead-assignee share

H02N 9.7% D04H 9.7% F01B 9.7% B31D 9.9%

Questions about B28C

Which company holds the most patents in B28C?

Oshkosh Corporation leads B28C with 50 patents (9.8% of the subclass). By PatentsView assignee type, us corporations account for 71% of class grants.

Which B28C assignees grew fastest recently?

Among assignees with ≥5 grants in B28C, Oshkosh Corporation shows the highest company-wide grant multiple (2.23x: 130 grants in 2019–2021 → 290 in 2022–2024) while holding 50 patents in this subclass. Growth is company-wide, not class-only.

How does B28C compare inside parent class B28?

Inside B28 (Working Cement, Clay, OR Stone), B28C ranks #3 of 3 subclasses by grant volume and holds 9.9% of the parent class total. The largest sibling is B28B (3,309 grants).

What to do with this data

B28C in context - here's where to go next.

Oshkosh Corporation leads B28C with 50 grants in this class. See full portfolio
B28C ranks #540 of 670 by grant volume among all tracked CPC technology areas. See the ranking
Inside parent class B28, the largest sibling subclass is B28B with 3,309 grants. Explore B28B

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

Methodology - B28C figures are USPTO PatentsView granted-utility totals for this subclass (511 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.