TONER AND IMAGE FORMING METHOD

• US 20070207399A1
• Filed: 03/02/2007
• Published: 09/06/2007
• Est. Priority Date: 03/06/2006
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Kato, Hiroaki, Mikuriya, Yoshihiro, Kurose, Katsunori, Yasunaga, Hideaki, Ishikawa, Yoshimichi, KADOTA, Takuya, Nakamura, Minoru, Inoue, Masahide, Yamamoto, Atsushi, Hagi, Masayuki
• Granted Patent: US 8,053,154 B2
• Time in Patent Office: Days
• US Class Current: 430/108.400
• CPC Class Codes: G03G 9/09708 Inorganic compounds
• CPC Class Codes: G03G 9/09725 Silicon-oxides; Silicates
• CPC Class Codes: G03G 9/09783 Organo-metallic compounds

Abstract

Toner for electrostatic charge development wherein no scumming occurs, and toner leakage caused by charge defect of the toner on a developing roller can be inhibited, and an excellent image stability is obtained is provided.

The toner used for an image forming method having a latent electrostatic image forming step of forming a latent electrostatic image on a latent electrostatic image bearing member primarily charged, a developing step of developing the latent electrostatic image by each toner which multiple developing devices have to form a toner image on the latent electrostatic image bearing member, a transferring step of transferring the toner image with respective colors formed on the latent electrostatic image bearing member onto a recording material and a fixing step of fixing the toner image transferred onto the recording material, wherein the toner comprises a colorant and a resin and contains an organic boron compound represented by a following chemical formula (A) as a charge controlling agent, further the toner is treated with an inorganic fine particle and at least one of the inorganic particles is a magnesium silicate compound represented by a following general formula [2] is provided.

wherein X is an alkali metal, R₁, R₂, R₃ or R₄ each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom.

Mg_xSi_yO(_x+2y) [2]

wherein x and y are integers.

Claims

1. A toner comprising:

toner particles which comprise a binding resin,a colorant,and a charge controlling agent, and

external additives which comprise an inorganic particle,

wherein the charge controlling agent is an organic boron compound represented by a following chemical formula (A);

wherein B is boron, X is an alkali metal, R₁, R₂, R₃ or R₄ each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, multiple R₁, R₂, R₃ or R₄ may be present, when the multiple R₁, R₂, R₃ or R₄ are present, they may be different or the same, and n represents an positive integer of 1 to 5;

and the inorganic particle is a magnesium silicate compound represented by the following general formula (2);

Mg_xSi_yO_(x+2y)  

 

(2)

wherein x and y are integers, wherein Mohs hardness is 4.5 to 8.

2. The toner according to claim 1, wherein the organic boron compound represented by the chemical formula (A) is an organic boron compound represented by the following chemical formula [1]:

wherein x represents an alkali metal

3. The toner according to claim 1, wherein an average primary particle diameter of the magnesium silicate compound is 0.05 μ

m to 0.15 μ

m and an average secondary particle diameter is 0.2 μ

m to 0.6 μ

m, and an amount of the magnesium silicate compound added is 0.1 parts by mass to 5 parts by mass relative to 100 parts by mass of the toner base.

4. The toner according to claim 1, wherein the magnesium silicate compound is one selected from the group consisting of forsterite, steatite and enstatite.

5. The toner according to claim 1, wherein the charge controlling agent is included in the toner in an amount of from 0.5 to 3 parts by weight based on 100 parts by weight of the resin.

6. A non-magnetic one-component image forming method comprising:

forming a latent electrostatic image on an latent electrostatic bearing member primarily charged,

developing the latent electrostatic image by various color toners which multiple developing devices have to form a toner image on the latent electrostatic bearing member by a one-component developing method,

transferring the toner image with various colors formed on the latent electrostatic bearing member onto a recording material, and

fixing the toner image transferred onto the recording material,

wherein the toner comprising a binding resin, a colorant, an inorganic particle and a charge controlling agent,

wherein the charge controlling agent is an organic boron compound represented by a following chemical formula (A);

wherein B is boron, X is an alkali metal, R₁, R₂, R₃ or R₄ each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, multiple R₁, R₂, R₃ or R₄ may be present, when the multiple R₁, R₂, R₃ or R₄ are present, they may be different or the same, and n represents an positive integer of 1 to 5;

and the inorganic particle is a magnesium silicate compound represented by the following general formula (2);

Mg_xSi_yO_(x+2y)  

 

(2)

wherein x and y are integers, wherein Mohs hardness is 4.5 to 8.

7. The non-magnetic one-component image forming method according to claim 6, wherein the developing device used in the developing step has a developing roller and a toner layer thickness regulating member which regulates a layer thickness of the toner formed on the developing roller surface.

8. The non-magnetic one-component image forming method according to claim 7, wherein at least a surface layer of the developing roller is composed of a metal and at least a surface layer of the toner layer thickness regulating member is composed of an elastic body.

9. The non-magnetic one-component image forming method according to claim 7, wherein at least a surface layer of the developing roller is composed of an elastic body and at least a surface layer of the toner layer thickness regulating member is composed of a metal.

10. A process cartridge comprising:

a latent electrostatic image bearing member and at least one unit selected from a charging unit, a developing unit and a cleaning unit, and detachable to an image forming apparatus main body,

wherein the developing unit holds a toner,and the toner which comprises a binding resin, a colorant, an inorganic particle and a charge controlling agent,

wherein the charge controlling agent is an organic boron compound represented by a following chemical formula (A);

wherein B is boron, X is an alkali metal, R₁, R₂, R₃ or R₄ each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, multiple R₁, R₂, R₃ or R₄ may be present, when the multiple R₁, R₂, R₃ or R₄ are present, they may be different or the same, and n represents an positive integer of 1 to 5;

and the inorganic particle is a magnesium silicate compound represented by the following general formula (2);

Mg_xSi_yO_(x+2y)  

 

(2)

wherein x and y are integers, wherein Mohs hardness is 4.5 to 8.