IP Library Granted Patent US 12,541,159
Granted Patent B2
US 12,541,159 · App. 17/774,606 · Granted Feb 3, 2026

Toner particles for developing electrostatically charged image and toner composition for developing electrostatically charged image

Inventors: Yudai Kimura (Shizuoka, JP); Ikuko Yatsuzuka (Shizuoka, JP); Takayuki Sano (Shizuoka, JP)
Assignee: TOMOEGAWA CORPORATION
G03G9/09314
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Quick Facts
Patent No.
US 12,541,159
App. No.
17/774,606
Granted
Feb 3, 2026
Kind
B2
Abstract

A toner particle for developing an electrostatically charged image includes a toner base particle and a resin coating covering the toner base particle. The toner base particle includes a recess on a surface of the toner base particle. The recess has a depth of 50 nm to 500 nm. The resin coating includes a coating (A) portion having a thickness of 10 nm or more and less than 50 nm and a coating (B) portion having a thickness of 50 nm or more and 500 nm or less, and the coating (B) portion is present on the recess.

Claims (32)

1 . A toner particle for developing an electrostatically charged image, the toner particle comprising:

a toner base particle; and

a resin coating covering a surface of the toner base particle, wherein

the toner base particle includes a recess on the surface of the toner base particle,

the recess has a depth of 50 nm to 500 nm,

the resin coating includes a coating (A) portion having a thickness of 10 nm or more and less than 50 nm and a coating (B) portion having a thickness of 50 nm or more and 500 nm or less, and

the coating (B) portion is present on the recess,

a ratio of a sum of the coating (B) portion included in the resin coating to a sum of the resin coating included in the toner particles for developing the electrostatically charged image is 30 to 60%, and

the resin coating is formed with resin fine particles that are produced without using an emulsifier and are composed of a material that is different from the toner base particle, and that have particle sizes,

the standard deviation of the particle sizes of the resin fine particle is 0.15 or less.

2 . The toner particle for developing an electrostatically charged image according to claim 1 , wherein the coating (B) portion is a resin layer in which a plurality of resin layers are laminated.

3 . The toner particle for developing an electrostatically charged image according to claim 2 , wherein in the coating (B) portion, a laminating direction of the plurality of resin layers is a direction away from the surface of the toner base particle.

4 . The toner particle for developing an electrostatically charged image according to claim 1 , wherein an average particle size of the toner particle for developing an electrostatically charged image is 3 to 15 μm.

5 . The toner particle for developing an electrostatically charged image according to claim 2 , wherein an average particle size of the toner particle for developing an electrostatically charged image is 3 to 15 μm.

6 . The toner particle for developing an electrostatically charged image according to claim 3 , wherein an average particle size of the toner particle for developing an electrostatically charged image is 3 to 15 μm.

7 . A toner composition for developing an electrostatically charged image, the toner composition comprising:

the toner particle for developing an electrostatically charged image according to claim 1 .

8 . A toner composition for developing an electrostatically charged image, the toner composition comprising:

the toner particle for developing an electrostatically charged image according to claim 2 .

9 . A toner composition for developing an electrostatically charged image, the toner composition comprising:

the toner particle for developing an electrostatically charged image according to claim 3 .

10 . A toner composition for developing an electrostatically charged image, the toner composition comprising:

the toner particle for developing an electrostatically charged image according to claim 4 .

11 . A toner composition for developing an electrostatically charged image, the toner composition comprising:

the toner particle for developing an electrostatically charged image according to claim 5 .

12 . A toner composition for developing an electrostatically charged image, the toner composition comprising:

the toner particle for developing an electrostatically charged image according to claim 6 .

13 . The toner particle for developing an electrostatically charged image according to claim 4 , wherein

an average particle size of the resin fine particles is ranged from 20 to 50 nm.

14 . The toner particle for developing an electrostatically charged image according to claim 13 , wherein

the resin fine particle is formed of a polymer of a monomer having an unsaturated bond, and

a mass average molecular weight of the polymer forming the resin fine particle is ranged from 20,000 to 1,500,000.

Assignments (2)
CHANGE OF NAME Recorded Nov 20, 2025
From: TOMOEGAWA CO., LTD.
To: TOMOEGAWA CORPORATION
Reel/Frame 073675/0888 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded May 5, 2022
From: KIMURA, YUDAI; YATSUZUKA, IKUKO; SANO, TAKAYUKI
To: TOMOEGAWA CO., LTD.
Reel/Frame 059828/0001 →
Priority Claims (1)
JP 2019-212354 · Nov 25, 2019 · national
Continuity (1)
Related Publication 20220404729A1 · Dec 22, 2022
References Cited (20)
US 5981129A · Akazawa · 1999 [cited by applicant]
US 10228628B2 · Yamashita · 2019 [cited by applicant]
US 20070042285A1 · Kitani · 2007 [cited by examiner]
US 20090286176A1 · Ohmura · 2009 [cited by applicant]
US 20090297224A1 · Kawase et al. · 2009 [cited by applicant]
US 20150017582A1 · Ozawa et al. · 2015 [cited by applicant]
US 20180031991A1 · Yamashita · 2018 [cited by applicant]
US 20180329330A1 · Era · 2018 [cited by examiner]
EP 1757992 · 2008 [cited by applicant]
JP H10293420A · 1998 [cited by applicant]
JP 2007057575A · 2007 [cited by applicant]
JP 2009301026A · 2009 [cited by applicant]
JP 2012037629A · 2012 [cited by applicant]
JP 2013182201 · 2013 [cited by applicant]
JP 2014026126A · 2014 [cited by applicant]
JP 2017116712A · 2017 [cited by applicant]
JP 2018017884A · 2018 [cited by applicant]
JP 2018031866A · 2018 [cited by applicant]
International Preliminary Report on Patentability for the corresponding International application No. PCT/JP2020/043601 mailed May 17, 2022, which includes English translation of Written opinion of the International Sea… [cited by applicant]
The extended European search report of the corresponding EP application No. 20892573.5 mailed Nov. 22, 2023. [cited by applicant]