Carrier for electrophotographic developer, image forming method, and process cartridge

A developer-carrying and developing-agent technology, which is applied in the direction of developing agent, electric recording process using charge pattern, electric recording process using charge pattern, etc., can solve the problem that the reproducibility of the image to be developed is damaged, and it is difficult to completely prevent color staining , resistivity increase, etc., to achieve the effect of inhibiting carrier adhesion and inhibiting color staining

Active Publication Date: 2008-06-25
RICOH KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0024] However, the specific gravity between the carrier and the toner is indeed significantly different, and therefore, it is difficult to sequentially supply the supply developer into the developing device without making it interfere with the toner supply as disclosed in JP-A No. 08-234550. container, wherein the supply developer contains one of various carriers with different physical properties and toner; moreover, in the developer, the amount of toner is greater than the amount of carrier, so in the long run , the carrier tends to degrade and cannot form a stable image
[0025] Furthermore, as described in JP-A No. 08-234550, when only the coating amount of the silicone coating layer to be coated on the carrier core material is increased in order to increase the resistivity of the supply carrier, the charge amount of the carrier tends to decrease while the resistivity increases, and as a result, there arises such a problem that the reproducibility of the image to be developed is impaired and background smears (smear) are generated
[0030] However, there are still problems of durability and heat resistance, and there are also problems that consumption of the toner on the surface of the carrier occurs, instability of the charge amount caused thereby, toner fogging, etc.; and there are also Necessary to improve environmental resistance
[0037] However, in recent years, there has been a clear tendency to speed up the image forming device of the above-mentioned electrophotographic system, and in association with this, the pressure on the developer has grown significantly
Therefore, even with the proposals of JP-A Nos. 07-140723, 08-179570, and 08-286429, it is difficult to completely prevent color stains caused by migration of carbon black to images

Method used

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  • Carrier for electrophotographic developer, image forming method, and process cartridge
  • Carrier for electrophotographic developer, image forming method, and process cartridge
  • Carrier for electrophotographic developer, image forming method, and process cartridge

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0363]Pour 724 parts of adducts of bisphenol A and 2 moles of ethylene oxide, 276 parts of isophthalic acid and 2 parts of dibutyltin oxide into a reaction vessel equipped with a condenser, a stirrer and a nitrogen inlet, and allow the The mixture was reacted at 230° C. under normal pressure for 8 hours, then further made to react under a reduced pressure of 10 to 15 mmHg for 5 hours, then cooled to 160° C.; then 32 parts of phthalic anhydride were added to the reactant and the The mixture was reacted for 2 hours.

[0364] Next, the reactant was cooled to 80° C., and reacted with 188 parts of isophorone diisocyanate in ethyl acetate for 2 hours to prepare isocyanate-containing prepolymer P1.

[0365] Then 267 parts of prepolymer P1 and 14 parts of isophoronediamine were reacted at 50° C. for 2 hours, thereby preparing urea-modified polyester U1 with a mass average molecular weight of 64,000.

[0366] Similar to the above description, the adduct of 724 parts of bisphenol A and...

preparation Embodiment 1

[0377] Pigment: C.I. Pigment Yellow 155 40 parts

[0378] Binder resin: polyester resin A 60 parts

[0379] 30 parts of water

[0380] The above ingredients were mixed in a Henschel mixer to prepare a mixture containing pigment agglomerates into which water had been immersed. The mixture was kneaded for 45 minutes with a twin roll set at a surface temperature of 130° C., and then ground to a size of about 1 mmΦ with a pulverizer to prepare a masterbatch M1.

Embodiment A

[0382] A solution of 240 parts of binder resin B1 in ethyl acetate and MEK, 20 parts of pentaerythritol tetrabehenate (melting point: 81° C., melt viscosity: 25 cps) and 8 parts of masterbatch M1 were introduced into a beaker, and then The mixture was stirred with a TK type homomixer at 12000 rpm at 60° C. to be uniformly dissolved and dispersed to prepare a toner component liquid.

[0383] 706 parts of deionized water, 294 parts of a 10% suspension of hydroxyapatite (Supertite 10, manufactured by Nippon Chemical Industrial Co.) and 0.2 parts of sodium dodecylbenzenesulfonate were added to a beaker and uniformly dissolved to prepare solution.

[0384] Then the solution was heated to 60° C. and the toner component solution was poured into the beaker while stirring at 12000 rpm for 10 minutes with a TK type homomixer.

[0385] The mixture liquid was then transferred into a Korben equipped with a stirrer and a thermometer, and heated to 98° C. to remove the solvent, then filtere...

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PUM

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Abstract

A carrier for electrophotographic developer that comprises a particle of core material and a coating layer that coats the particle of core material, wherein a toner and a carrier are supplied into a developing device where a toner and a carrier being contained, and the surplus developer within the developing device is discharged, a coating layer on at least one of the supplied carrier and the carrier contained in the developing device comprises a white conductive fine particle that includes tin dioxide and indium oxide on a base material.

Description

technical field [0001] The present invention relates to a carrier for an electrophotographic developer of a two-component developer, an electrophotographic developer, an image forming method, an image forming apparatus, an apparatus for supplying a developer, and a process cartridge. Background technique [0002] In electrophotographic image forming apparatuses such as copiers and printers, a latent image is formed by exposing the surface of a uniformly charged image bearing member, a toner image is formed by developing the latent image, and then the toner image is transferred to Transfer parts, such as recording paper. The transfer member bearing the toner image passes through the fixing unit, and the toner is fixed on the transfer member by heat and / or pressure. [0003] In an image forming apparatus, a developing device for developing a latent image on an image bearing member is classified into a one-component developing type and a two-component developing type in which ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G03G9/10G03G15/08G03G9/087G03G13/00G03G15/00G03G21/18
CPCG03G9/1131G03G9/1139G03G9/113
Inventor 长山将志近藤富美雄八木慎一郎岩附仁
Owner RICOH KK
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