Toner, developer, toner housing unit and image forming apparatus

Patent metadata

Field	Value
Publication number	US-10274853-B2
Application number	US-201615188088-A
Country	US
Kind code	B2
Filing date	Jun 21, 2016
Priority date	Jun 29, 2015
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

A toner includes a binder resin; a release agent; and two or more inorganic fine particles as external additives. At least one of the inorganic fine particles is silica. When an ultrasonic oscillation is applied to a dispersion including the toner and a dispersant and a rate of the silica releasing from the toner is 20% based on total silica, an application energy of the ultrasonic oscillation is from 8 to 14 kJ, and from 70 to 130 kJ when the rate of the silica releasing from the toner is 50%.

First claim

What is claimed is:

1. A toner, comprising:
a toner base particle which comprises a binder resin and a release agent; and
external additives which comprise two or more inorganic fine particles,
wherein at least one of the inorganic fine particles is silica,
wherein the binder resin has a group derived from a phenoxy acetic acid or a benzoic acid, the group being a substitute for a hydroxyl group at an end of a chain of the binder resin, and
wherein when an ultrasonic oscillation having a frequency of 20 kHz is applied to a dispersion in which 3.75 g of the toner is dispersed in 50 mL of a dispersant which is a mixture of ion exchanged water and 0.5% by mass of polyoxyalkylene alkyl ether dissolved in the ion exchanged water, under a temperature of 40° C. or less, an application energy of the ultrasonic oscillation is from 8 to 14 kJ when a rate of the silica releasing from the toner is 20 mass % based on total silica, and from 70 to 130 kJ when the rate of the silica releasing from the toner is 50 mass % based on the total silica.

2. The toner of claim 1 , wherein the content of the silica is from 3.5 to 4.5 parts by mass per 100 parts by mass of the toner base particle.

3. The toner of claim 1 , wherein in a molecular weight distribution of tetrahydrofuran(THF)-soluble components of the toner, when a molecular weight M is selected within a molecular weight range of from 300 to 5,000, a difference between the maximum value and the minimum value of a peak intensity in a range of M±300 is not greater than 30,
wherein the peak intensity is a relative value when the maximum intensity is set to 100 in a molecular weight range not greater than 20,000 in a molecular weight distribution curve plotted on a diagram in which a vertical axis is intensity and a horizontal axis is molecular weight through GPC measurement.

4. The toner of claim 1 , wherein the binder resin comprises a crystalline resin having a melting point of from 50° C. to 65° C.

5. The toner of claim 1 , wherein the silica has an average circularity of from 0.4 to 0.8.

6. A developer comprising the toner according to claim 1 .

7. A developer housing unit comprising the developer according to claim 6 .

8. An image forming apparatus, comprising:
an electrostatic latent mage bearer to bear an electrostatic latent mage;
an electrostatic latent mage former to form an electrostatic latent image on the electrostatic latent mage bearer;
the developer according to claim 6 ;
an image developer to develop the electrostatic latent image with the developer to form a visible image;
a transferer to transfer the visible image onto a recording medium, and
a fixer to fix the visible image on the recording medium.

Assignees

• Itoh Takayuki
• Watanabe Naohiro
• Honda Takahiro
• Sakashita Shingo
• Inoue Daisuke
• Takahashi Rintaro
• Satoh Ayumi
• Ricoh Co Ltd

Inventors

• Itoh Takayuki
• Watanabe Naohiro
• Honda Takahiro
• Sakashita Shingo
• Inoue Daisuke
• Takahashi Rintaro
• Satoh Ayumi

Classifications

• G03G9/09725

  Silicon-oxides; Silicates · CPC title

• G03G9/0821

  characterised by physical parameters (magnetic parameters G03G9/083) · CPC title

• G03G9/0827

  characterised by their shape, e.g. degree of sphericity · CPC title

• G03G9/08755 Primary

  Polyesters · CPC title

• G03G15/0865

  Arrangements for supplying new developer · CPC title