Magenta toner, developer, and image forming apparatus

Patent metadata

Field	Value
Publication number	US-9488925-B2
Application number	US-201514630783-A
Country	US
Kind code	B2
Filing date	Feb 25, 2015
Priority date	Mar 4, 2014
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

A magenta toner for electrophotography, including:
a polyester resin; and a colorant containing a naphthol-based pigment, wherein the magenta toner for electrophotography satisfies requirements <1> and <2> below: <1> [G′(100)(THF insoluble matter)] is 1.0×10 5 Pa to 1.0×10 7 Pa, and a ratio of [G′(40)(THF insoluble matter)] to the [G′(100)(THF insoluble matter)] is 3.5×10 or less, where the [G′(100)(THF insoluble matter)] is a storage modulus at 100° C. of THF insoluble matter of the toner and the [G′(40)(THF insoluble matter)] is a storage modulus at 40° C. of the THF insoluble matter of the toner; and <2> an X-ray diffraction pattern of the naphthol-based pigment in a crystalline state has a plurality of peaks in a range of 0°≦2θ≦35°, and a sum of half value widths of the peaks is 5° to 10°.

First claim

What is claimed is:

1. A magenta toner for electrophotography, comprising:
a polyester resin; and
a colorant containing a naphthol-based pigment,
wherein the magenta toner for electrophotography satisfies requirements <1> and <2> below:
<1> [G′(100) (THF insoluble matter)] is 1.0×10 5 Pa to 1.0×10 7 Pa, and a ratio of [G′(40) (THF insoluble matter)] to the [G′(100) (THF insoluble matter)] is 3.5×10 or less, where the [G′(100) (THF insoluble matter)] is a storage modulus at 100° C. of THF insoluble matter of the toner and the [G′(40) (THF insoluble matter)] is a storage modulus at 40° C. of the THF insoluble matter of the toner; and
<2> an X-ray diffraction pattern of the naphthol-based pigment in a crystalline state has a plurality of peaks in a range of 0°≦2θ≦35°, and a sum of half value widths of the peaks is 5° to 10°.

2. The magenta toner according to claim 1 , wherein 50% by mass or less of the naphthol-based pigment is present within a region of 1,000 nm from a surface of the toner toward a center thereof.

3. The magenta toner according to claim 1 , wherein the magenta toner has a glass transition temperature (Tg1st) of 20° C. to 50° C., where the glass transition temperature (Tg1st) is measured in first heating of differential scanning calorimetry (DSC).

4. The magenta toner according to claim 1 , wherein the magenta toner has a glass transition temperature (Tg2nd) of 0° C. to 30° C., where the glass transition temperature (Tg2nd) is measured in second heating of differential scanning calorimetry (DSC).

5. The magenta toner according to claim 1 , wherein the polyester resin contains a non-crystalline polyester resin insoluble in THF and a polyester resin soluble in THF.

6. The magenta toner according to claim 5 , wherein the non-crystalline polyester resin insoluble in THF has a Tg of 20° C. or lower.

7. The magenta toner according to claim 5 , wherein the polyester resin further comprises a crystalline polyester resin.

8. A developer, comprising:
the magenta toner according to claim 1 ; and
a carrier.

9. An image forming apparatus, comprising:
an electrostatic latent image bearer;
an electrostatic latent image forming unit configured to form an electrostatic latent image on the electrostatic latent image bearer; and
a developing unit configured to develop the electrostatic latent image formed on the electrostatic latent image bearer with a toner to form a visible image,
wherein the toner is the magenta toner according to claim 1 .

Assignees

• Chiba Ryuta
• Nakayama Shinya
• Sugimoto Tsuyoshi
• Yamada Hiroshi
• Chiba Susumu
• Nagai Shinsuke
• Yamashita Hiroshi
• Shiba Masana
• Ricoh Co Ltd

Inventors

• Chiba Ryuta
• Nakayama Shinya
• Sugimoto Tsuyoshi
• Yamada Hiroshi
• Chiba Susumu
• Nagai Shinsuke
• Yamashita Hiroshi
• Shiba Masana

Classifications

• G03G9/08795

  characterised by their chemical properties, e.g. acidity, molecular weight, sensitivity to reactants · CPC title

• G03G9/092

  Quinacridones · CPC title

• G03G9/08755 Primary

  Polyesters · CPC title

• G03G9/08797

  characterised by their physical properties, e.g. viscosity, solubility, melting temperature, softening temperature, glass transition temperature · CPC title