Patents by Inventor Tsukiko TAKAHASHI

Tsukiko TAKAHASHI has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 11796931
    Abstract: A toner is provided. The toner comprises colored particles and external additives present on surfaces of the colored particles. The colored particles each comprise a core and a shell layer. The core contains a crystalline resin, a non-crystalline resin, and a colorant. The shell layer contains a resin and has a thickness of from 30 to 130 nm. The external additives comprise a metal oxide and a silicon compound. An electronegativity X(A) of the metal oxide and an electronegativity X(Si) of the silicon compound satisfy a relation 0.5?X(A)/X(Si)?0.8. A proportion of an amount of the metal oxide directly adhered to the surfaces of the colored particles to a total amount of the metal oxide present on the colored particles is from 60% to 90% by mass.
    Type: Grant
    Filed: October 1, 2020
    Date of Patent: October 24, 2023
    Assignee: RICOH COMPANY, LTD.
    Inventors: Akio Takei, Takahiro Honda, Tsukiko Takahashi, Tsuneyasu Nagatomo
  • Publication number: 20230280670
    Abstract: [Summary] An object of the present invention is to provide a toner that has both low-temperature fixability and heat-resistant storage stability, suppresses contamination of cleaning parts and photoconductors, and has excellent charging stability. [Tasks] A toner includes toner based particles containing a binder resin, a colorant, and a wax; and fine resin particles and an inorganic external additive that are present on a surface of the toner based particles, wherein a coverage of the fine resin particles is in a range from 30% to 70%, and wherein the inorganic external additive covers a surface of oxide of a metal element with hydroxide of a metal element.
    Type: Application
    Filed: February 28, 2023
    Publication date: September 7, 2023
    Applicant: Ricoh Company, Ltd.
    Inventors: Tsukiko TAKAHASHI, Mitsuaki Hirose, Yohichi Kitagawa, Suzuka Karato, Hiroshi Yamada
  • Publication number: 20230195005
    Abstract: Provided is a toner including toner particles. Each of the toner particles includes a toner base particle including a binder resin, resin particles covering the toner base particle, and zinc stearate particles serving as an external additive. In each of the toner particles, a coverage rate of the toner base particle with the resin particles is 30% or greater and 70% or less. The zinc stearate particles have a volume average particle diameter of 3 ?m or greater and 20 ?m or less.
    Type: Application
    Filed: December 20, 2022
    Publication date: June 22, 2023
    Inventors: Taishi YAMASHITA, Yohichi KITAGAWA, Tsukiko TAKAHASHI, Mitsuaki HIROSE, Daisuke INOUE
  • Publication number: 20230185210
    Abstract: A glittering toner includes: a flat metallic pigment having a surface coated with a resin; a polyester-styrene acrylic composite resin; and a polyester resin. When a solubility parameter of the polyester-styrene acrylic composite resin is represented by SP1 (cal/cm3)1/2 and a solubility parameter of the polyester resin is represented by SP2 (cal/cm3)1/2, the SP1 and the SP2 satisfy a relational expression (1): [SP2?SP1>0.3] and the SP1 satisfies a relational expression (2): [10<SP1].
    Type: Application
    Filed: December 12, 2022
    Publication date: June 15, 2023
    Inventors: Tsukiko TAKAHASHI, Kohsuke SATOH, Kazumi SUZUKI, Daichi HISAKUNI, Kazuoki FUWA
  • Publication number: 20230152724
    Abstract: A toner includes toner base particles each including a binder resin and a releasing agent, resin particles, and an external additive. Resin particles, from among the resin particles in the toner, and the external additive are deposited on a surface of each of the toner base particles. A standard deviation of a distance between resin particles next to one another on the surface is less than 600 nm, the resin particles next to one another being from among the resin particles deposited on the surface. The external additive includes primary particles each standing alone and non-spherical cohesive particles each including cohered primary particles. A proportion of the primary particles each standing alone per 1,000 particles of the external additive is 30% or less, the particles of the external additive in the per 1,000 particles being the primary particles each standing alone and the cohesive particles.
    Type: Application
    Filed: November 9, 2022
    Publication date: May 18, 2023
    Inventors: Suzuka KARATO, Mitsuaki HIROSE, Hiroshi YAMADA, Yohichi KITAGAWA, Tsukiko TAKAHASHI
  • Publication number: 20230040461
    Abstract: A toner includes: toner base particles including a binder resin, a colorant, an inorganic filler, and a release agent; and an external additive. An average circularity of the toner is 0.974 or more but 0.985 or less. A surface roughness parameter Sz of a surface of the toner is 200 nm or more but 500 nm or less, the surface roughness parameter Sz being measured with an atomic force microscope (AFM).
    Type: Application
    Filed: July 25, 2022
    Publication date: February 9, 2023
    Applicant: Ricoh Company, Ltd.
    Inventors: Daisuke Inoue, Mitsuaki Hirose, Yohichi Kitagawa, Tsukiko Takahashi, Kenji Komito, Akihiko Moki
  • Publication number: 20220326632
    Abstract: [Object] An object of the invention is to provide a toner that can both achieve a higher level of low temperature fixability and suppression of the toner scattering. [Means of Achieving the Object] The disclosure is to provide a toner, including base-particles, and an external-additive, wherein a glass-transition temperature obtained from a DSC-curve at a second-warming of a THF-insoluble component is ?50° C. or higher and 10° C. or lower, wherein an average circularity of the toner is 0.975 or more and 0.985 or lower, wherein the toner satisfies the following formula: 1.5?Bt?0.025?Ct?3.0, wherein the Bt [m2/g] is a BET-specific-surface area of the toner-particles, and the Ct [%] is a coverage by the external-additive, and, at least a portion of a surface of the external-additive is coated with either an oxide of a metallic element, a hydroxide of the metallic element, or both.
    Type: Application
    Filed: March 31, 2022
    Publication date: October 13, 2022
    Applicant: Ricoh Company, Ltd.
    Inventors: Keiji MAKABE, Akira Tanaka, Hidekazu Kakinuma, Tsukiko Takahashi
  • Publication number: 20210116830
    Abstract: A toner is provided. The toner comprises colored particles and external additives present on surfaces of the colored particles. The colored particles each comprise a core and a shell layer. The core contains a crystalline resin, a non-crystalline resin, and a colorant. The shell layer contains a resin and has a thickness of from 30 to 130 nm. The external additives comprise a metal oxide and a silicon compound. An electronegativity X(A) of the metal oxide and an electronegativity X(Si) of the silicon compound satisfy a relation 0.5?X(A)/X(Si)?0.8. A proportion of an amount of the metal oxide directly adhered to the surfaces of the colored particles to a total amount of the metal oxide present on the colored particles is from 60% to 90% by mass.
    Type: Application
    Filed: October 1, 2020
    Publication date: April 22, 2021
    Inventors: Akio TAKEI, Takahiro HONDA, Tsukiko TAKAHASHI, Tsuneyasu NAGATOMO