Latent electrostatic image developing toner

Patent metadata

Field	Value
Publication number	US-9285695-B2
Application number	US-201214345308-A
Country	US
Kind code	B2
Filing date	Sep 12, 2012
Priority date	Sep 16, 2011
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

A toner including: a core particle containing at least a binder resin, a colorant and a releasing agent; and a shell on a surface of the core particle, wherein the toner gives a supernatant having a transmittance of 50% to 95% with respect to light having a wavelength of 800 nm, where the supernatant is formed after 3 g of the toner is added to 40 g of ion-exchange water containing 0.5% by mass of sodium dodecyl sulfate, followed by stirring for 90 min and by irradiating with ultrasonic waves of 20 kHz and 80 W for 5 min, and a liquid containing the toner dispersed therein is centrifugated at 3,000 rpm for 5 min.

First claim

The invention claimed is:

1. A toner, comprising:
a core particle comprising a binder resin, a colorant and a releasing agent; and
a shell on a surface of the core particle,
wherein a supernatant of the toner has a transmittance of 50% to 95% with respect to light having a wavelength of 800 nm, where the supernatant is obtained by adding 3 g of the toner to 40 g of ion-exchange water comprising 0.5% by mass of sodium dodecyl sulfate to form a mixture, stirring the mixture for 90 min, irradiating the mixture with ultrasonic waves of 20 kHz and 80 W for 5 min, and then centrifuging the mixture at 3,000 rpm for 5 min.

2. The toner of claim 1 , wherein the shell comprises a protrusion, and the shell is formed by fine resin particles attached on the surface of the core particle.

3. The toner of claim 2 , wherein the toner is obtained by a method comprising: dissolving or dispersing, in an organic solvent, the binder resin, the colorant and the releasing agent, to obtain a solution or dispersion liquid; dispersing the solution or dispersion liquid in an aqueous medium to form oil droplets; and attaching the fine resin particles to surfaces of the oil droplets.

4. The toner of claim 2 , wherein the binder resin comprises a non-crystalline polyester resin, the fine resin particles are vinyl fine resin particles, and an amount of the vinyl fine resin particles is 3 parts by mass to 15 parts by mass per 100 parts by mass of the core particle.

5. The toner of claim 4 , wherein the vinyl fine resin particles comprise 80% by mass or more of an aromatic compound having a vinyl polymerizable functional group.

6. The toner of claim 4 , wherein the toner has a ratio of intensity at 700 cm −1 to intensity at 828 cm −1 of 0.30 or greater as measured by attenuated total reflection.

7. The toner of claim 1 , wherein the core particle comprises a crystalline polyester resin.

8. The toner of claim 1 , wherein the core particle comprises an isocyanate modified polyester resin.

9. The toner of claim 1 , wherein the releasing agent is at least one selected from the group consisting of paraffin wax, synthetic ester wax, polyolefin wax, carnauba wax, and rice wax.

10. The toner of claim 1 , wherein an amount of the releasing agent in the toner is 4.0% by mass to 8.0% by mass.

11. The toner of claim 1 , further comprising:
an external additive A; and
an external additive B,
wherein the external additive A is inorganic fine particles whose surfaces have been treated with silicone oil, and the external additive B is inorganic fine particles whose surfaces have been treated with an amino group-containing silane coupling agent.

12. The toner of claim 11 , wherein the toner has a ratio of intensity at 475 cm −1 to intensity at 828 cm −1 of 0.15 or greater as measured by attenuated total reflection.

13. The toner of claim 1 , wherein the shell comprises a plurality of fine resin particles such that a surface of the toner has a sea-island structure in which the surface of the core particle forms a sea and the fine resin particles form islands.

14. The toner of claim 13 , wherein a coverage rate of the plurality of fine resin particles on the surface of the toner is from 30 to 90%.

15. The toner of claim 13 , wherein the fine resin particles have a diameter of from 100 to 108 nm.

16. A developer, comprising:
a toner,
wherein the toner comprises a core particle comprising a binder resin, a colorant and a releasing agent, and a shell on a surface of the core particle, and
a supernatant of the toner has a transmittance of 50% to 95% with respect to light having a wavelength of 800 nm, where the supernatant is obtained by adding 3 g of the toner to 40 g of ion-exchange water comprising 0.5% by mass of sodium dodecyl sulfateto form a mixture, stirring the mixture for 90 min, irradiating the mixture with ultrasonic waves of 20 kHz and 80 W for 5 min, and then centrifuging the mixture at 3,000 rpm for 5 min.

17. An image forming apparatus, comprising:
a latent image bearing member configured to bear a latent image;
a charging unit configured to uniformly charge a surface of the latent image bearing member;
an exposing unit configured to expose the charged surface of the latent image bearing member to light based on image data, to thereby form a latent electrostatic image;
a developing unit comprising a developing roller and a toner-regulating blade and configured to supply a toner to the latent electrostatic image formed on the surface of the latent image bearing member to form a visible image using the developing roller and the toner-regulating blade where the developing roller is configured to come into contact with the latent image bearing member and bear the toner on a surface thereof and the toner-regulating blade is configured to regulate an amount of the toner on the surface of the developing roller and form a thin layer of the toner;
a transfer unit configured to transfer the visible image from the surface of the image bearing member onto a recording medium; and
a fixing unit configured to fix the visible image on the recording medium,
wherein the toner comprises a core particle comprising a binder resin, a colorant and a releasing agent, and a shell on a surface of the core particle, and
a supernatant of the toner has a transmittance of 50% to 95% with respect to light having a wavelength of 800 nm, where the supernatant is obtained by adding 3 g of the toner to 40 g of ion-exchange water comprising 0.5% by mass of sodium dodecyl sulfate to form a mixture, stirring the mixture for 90 min, irradiating the mixture with ultrasonic waves of 20 kHz and 80 W for 5 min, and then centrifuging the mixture at 3,000 rpm for 5 min.

18. The image forming apparatus of claim 17 , wherein the fixing unit is a heat-fixing unit.

19. The image forming apparatus of claim 17 , wherein the developing roller has an Asker C hardness of 60° to 85°.

20. The image forming apparatus of claim 17 , wherein the developing roller has a surface roughness of 0.5 μm to 3.0 μm.

Assignees

• Miki Tomoharu
• Kadota Takuya
• Mikuriya Yoshihiro
• Nozaki Tsuyoshi
• Ishikawa Yoshimichi
• Fuwa Kazuoki
• Fukao Tomohiro
• Ricoh Co Ltd

Inventors

• Miki Tomoharu
• Kadota Takuya
• Mikuriya Yoshihiro
• Nozaki Tsuyoshi
• Ishikawa Yoshimichi
• Fuwa Kazuoki
• Fukao Tomohiro

Classifications

• G03G9/09342

  Inorganic compounds · CPC title

• G03G9/0825 Primary

  characterised by their structure; characterised by non-homogenuous distribution of components (microcapsular toners G03G9/093) · CPC title

• G03G9/09392

  Preparation thereof · CPC title

• G03G9/09371

  obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• G03G9/08755

  Polyesters · CPC title