Toner for electrophotography, image forming method, and process cartridge

Patent metadata

Field	Value
Publication number	US-10274856-B2
Application number	US-201515110192-A
Country	US
Kind code	B2
Filing date	Jan 6, 2015
Priority date	Jan 17, 2014
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

A toner for electrophotography, which contains a binder resin, and a release agent, wherein a maximum value of loss tangent of the toner at 95° C. to 115° C. is 8 or greater, as a viscoelasticity of the toner is measured, where the loss tangent is represented by the following formula: Loss tangent (tan δ)=loss elastic modulus (G″)/storage elastic modulus (G′).

First claim

The invention claimed is:

1. A clear toner for electrophotography, comprising a toner in a form of a particle free from a colorant and containing:
a binder resin comprising a polyester resin;
a release agent comprising a monoester wax; and
a metal salt of formula (1):

wherein L 1 denotes:

wherein t-Bu denotes a t-butyl group,

wherein an acid value of the clear toner is 6 mgKOH/g to 12 mgKOH/g,
wherein the polvester resin has a weight average molecular weight (Mw) from 7,000 to 10,000,
wherein a ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polyester resin is 4 or less,
wherein the polyester resin has an acid value from 4.2 mgKOH/g to 13.2 mgKOH/g, and
wherein a maximum value of loss tangent of the toner at 97° C. to 113° C. is from 9 to 21, as a viscoelasticity of the clear toner is measured, where the loss tangent is represented by the following formula:
Loss tangent (tan δ)=loss elastic modulus ( G ″)/storage elastic modulus ( G ′).

2. The clear toner according to claim 1 , further comprising:
a wax-dispersing agent, which is a copolymer resin comprising at least styrene, butyl acrylate, and acrylonitrile as monomers.

3. The clear toner according to claim 1 , wherein the binder resin comprises 50 mass % or more, based on a total mass of the binder resin, of the polyester.

4. The clear toner according to claim 3 , comprising:
from 4 to 8 parts, relative to 100 parts of the clear toner, of the release agent; and
from 0.5 to 2 parts, relative to 100 parts of the clear toner, of the metal salt.

5. An image forming method, comprising:
superimposing a color toner and the clear toner according to claim 1 to form an image; and
simultaneously fixing the image, in which the color toner and the clear toner are superimposed, on a recording medium.

6. The image forming method according to claim 5 , wherein a difference in glossiness between the color toner and the clear toner is 30 or greater.

7. A process cartridge, comprising:
an image bearer; and
a developing device configured to develop an electrostatic latent image formed on the image bearer with a developer containing a clear toner and a carrier to form a visible image,
wherein the image bearer and the developing device are integratedly supported, and the process cartridge is detachably mounted in a main body of an image forming apparatus, and
wherein the clear toner is the clear toner according to claim 1 .

Assignees

• Nakajima Hisashi
• Suzuki Kazumi
• Nagayama Masashi
• Yamada Saori
• Yamauchi Yoshitaka
• Naito Yu
• Sekiguchi Yoshitaka
• Ricoh Co Ltd

Inventors

• Nakajima Hisashi
• Suzuki Kazumi
• Nagayama Masashi
• Yamada Saori
• Yamauchi Yoshitaka
• Naito Yu
• Sekiguchi Yoshitaka

Classifications

• G03G9/08711 Primary

  with esters of acrylic or methacrylic acid · CPC title

• G03G9/08797

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

• G03G9/08795

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

• G03G21/18

  using a processing cartridge {, whereby the process cartridge comprises at least two image processing means in a single unit} · CPC title

• G03G15/01

  for producing multicoloured copies · CPC title