Toner and two-component developer

• US 9,436,112 B2
• Filed: 09/11/2014
• Issued: 09/06/2016
• Est. Priority Date: 09/20/2013
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Iwasaki, Yosuke, Komatsu, Nozomu, Kobori, Takakuni, Takenaka, Kohji, Kaneko, Hideki, Hashimoto, Takeshi, Kanno, Ichiro, Fujikawa, Hiroyuki
• Primary Examiner(s): LE, HOA VAN
• Application Number:
  US14/483,975
• Publication Number:
  US 20150086917A1
• Time in Patent Office: 726 Days
• US Class Current: 1/1
• CPC Class Codes: G03G 9/0831 Chemical composition of the magnetic components
• CPC Class Codes: G03G 9/0837 Structural characteristics of the magnetic components, e.g. shape, crystallographic structure
• CPC Class Codes: G03G 9/09708 Inorganic compounds
• CPC Class Codes: G03G 9/09716 treated with organic compounds
• CPC Class Codes: G03G 9/09725 Silicon-oxides; Silicates
• CPC Class Codes: G03G 9/1085 with non-ferrous metal oxide, e.g. MgO-Fe2O3
• CPC Class Codes: G03G 9/1131 Coating methods; Structure of coatings
• CPC Class Codes: G03G 9/1133 obtained by reactions only involving carbon-to-carbon unsaturated bonds

Abstract

Provided are a toner and a two-component developer each of which: shows a small fluctuation in charge quantity and a small fluctuation in image density even under a high-temperature and high-humidity environment; and does not cause any member contamination even after endurance and hence can stably output an image. The toner and the two-component developer each have a feature in that positively chargeable strontium titanate fine particles are added to toner particles having fixed thereto negatively chargeable silica fine particles.

Claims

1. A toner, comprising:

toner particles each containing a binder resin, a wax, and a coloring agent; and

silica fine particles A and strontium titanate fine particles B present on surfaces of the toner particles,

wherein;

the silica fine particles A have a number-average particle diameter (D1) of 60 nm or more and 300 nm or less;

when

a coverage rate of the surfaces of the toner particles with the silica fine particles A is defined as a coverage rate X (%) and

a coverage rate with the silica fine particles A fixed to the surfaces of the toner particles is defined as a coverage rate Y (%),

the coverage rate X is 20% or more and 95% or less, and

a ratio [coverage rate Y/coverage rate X] of the coverage rate Y to the coverage rate X is 0.75 or more;

the strontium titanate fine particles B have a fixing rate, measured as indicated in the description, of 0.10 or more and 0.60 or less;

the silica fine particles A are negatively chargeable;

the strontium titanate fine particles B are positively chargeable;

an amount of the silica fine particles A is 2.0 parts by mass or more and 10.0 parts by mass or less when an amount of the toner particles is set to 100 parts by mass; and

an amount of the strontium titanate fine particles B is 0.2 part by mass or more and 1.0 part by mass or less when an amount of the toner particles is set to 100 parts by mass.

2. A toner according to claim 1, wherein:

surfaces of the silica fine particles A are treated with one of hexamethyldisilazane and a silicone oil; and

surfaces of the strontium titanate fine particles B are treated with one of a fatty acid and a fatty acid metal salt.

3. A toner according to claim 1, wherein:

primary particles of the strontium titanate fine particles B have a number-average particle diameter of 30 nm or more and 300 nm or less; and

the strontium titanate fine particles B each have a perovskite crystal, and particle shapes of the strontium titanate fine particles B each have one of a cubic shape, a rectangular parallelepiped shape, and a mixture thereof.

4. A toner according to claim 1, wherein the silica fine particles A have a number-average particle diameter (D1) of 70 nm or more and 280 nm or less.

5. A two-component developer, comprising:

a toner; and

a magnetic carrier,

wherein;

the toner comprises the toner according to claim 1; and

the magnetic carrier has a carrier core, and a surface of the carrier core is covered with a copolymer containing, as copolymerization components, a monomer having a structure represented by the following formula (1) and a macromonomer having a structure represented by the following formula (2);