# US 9,436,112 B2 · Toner and two-component developer

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- Number: US 9,436,112 B2
- Document ID: US9436112B2
- Status: Granted
- Kind: B2
- Application number: 14/483,975
- Filed: 2014-09-11
- Published: 2015-03-26
- Granted: 2016-09-06
- Earliest claimed: 2013-09-20
- Assignees: Canon Kabushiki Kaisha
- Applicants: Canon Kabushiki Kaisha
- Inventors: Yosuke Iwasaki; Nozomu Komatsu; Takakuni Kobori; Kohji Takenaka; Hideki Kaneko; Takeshi Hashimoto; Ichiro Kanno; Hiroyuki Fujikawa
- Web page: https://patentgrep.com/patent/US9436112B2

## CPC

- G03G 9/09725: {Silicon-oxides; Silicates}
- G03G 9/0831: {Chemical composition of the magnetic components}
- G03G 9/0837: {Structural characteristics of the magnetic components, e.g. shape, crystallographic structure}
- G03G 9/09708: {Inorganic compounds}
- G03G 9/09716: {treated with organic compounds}
- G03G 9/1085: {with non-ferrous metal oxide, e.g. MgO-Fe2O3}
- G03G 9/1131: {Coating methods; Structure of coatings}
- G03G 9/1133: {obtained by reactions only involving carbon-to-carbon unsaturated bonds}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## 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

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 1)

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.

### Claim 4 (depends on 1)

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.

### Claim 5 (depends on 1)

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):
in the formula, R1 represents a hydrocarbon group having 4 or more carbon atoms, and R2 represents H or CH3;
in the formula, A represents an alicyclic hydrocarbon group having 5 or more and 10 or less carbon atoms, or a polymer using, as a polymerization component, at least one kind of compound selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, styrene, and acrylonitrile, and R3 represents H or CH3.