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Magnetic carriers for electrophotographic developer, processes for producing same, and two-component developer

A magnetic carrier, electrophotography technology, applied in the direction of developer, electrography, optics, etc., can solve the problems of carrier chargeability degradation, image disorder carrier, toner consumption, etc., and achieve the suppression of carrier adhesion and magnetization value The effect of small deviation and excellent durability

Active Publication Date: 2015-02-11
TODA IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0014] Iron powder carriers and ferrite carriers are usually used to coat the surface of particles with resin, but because the true specific gravity of the above-mentioned iron powder carriers is as high as 7-8g / cm 3 , the true specific gravity of the ferrite carrier is as high as 4.5-5.5g / cm 3 Therefore, a large driving force is required for stirring in the developing machine, which is likely to cause a lot of mechanical loss, consumption of toner, deterioration of the chargeability of the carrier itself, and damage to the photoreceptor.
In addition, it is difficult to say that the adhesion between the particle surface and the coating resin is good. During use, the coating resin gradually peels off, causing a change in chargeability, and as a result, problems such as image disturbance and carrier adhesion occur.

Method used

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  • Magnetic carriers for electrophotographic developer, processes for producing same, and two-component developer
  • Magnetic carriers for electrophotographic developer, processes for producing same, and two-component developer
  • Magnetic carriers for electrophotographic developer, processes for producing same, and two-component developer

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Experimental program
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Effect test

preparation example Construction

[0137] The preparation of aqueous solution of methylol melamine is by adding melamine and aldehydes in water, while stirring, the reaction solution is heated up to a temperature range of 40 to 80° C., and the hydroxymethyl melamine solution is carried out at this temperature for 30 to 240 minutes, preferably 60 to 180 minutes. produced by methylation reactions.

[0138] At this time, it is desirable to slowly react the methylolation of melamine. The heating rate is preferably 0.5-1.5° C. / min, and the stirring rate is preferably 100-1000 rpm.

[0139] As the acid catalyst used in the present invention, a weak acid having an acid dissociation constant pKa of 3 to 6 can be suitably used, for example, formic acid, oxalic acid, acetic acid, etc. can be used, but acetic acid is most preferable. The content of the acid in the aqueous medium for forming composite particles is preferably 0.5 to 3% by weight.

[0140] The present invention is characterized in that an acidic aqueous so...

Embodiment 1

[0261] 〔Manufacture of spherical composite core particle〕

[0262]

[0263] Put the above material into a flask, stir at a stirring speed of 250rpm, raise the temperature to 85°C for 60 minutes, and react at this temperature for 120 minutes to solidify it, thereby carrying out the process of containing ferromagnetic iron oxide particles and binder resin. Generation of composite core particles.

[0264] Next, after cooling the contents in the flask to 30° C., the supernatant was removed, and the lower layer of the precipitate was washed with water and air-dried. Next, this was subjected to a heat treatment at 210° C. for 4 hours under a reduced pressure of 60 kPa under a nitrogen atmosphere, whereby spherical composite core particles 1 were obtained.

[0265] The spherical composite core particles 1 obtained here had an average particle diameter of 54 μm and a bulk density of 1.82 g / cm 3 , the specific gravity is 3.56g / cm 3 , the saturation magnetization value is 74.0Am ...

Embodiment 2～6、 comparative example 1～3

[0267] The spherical composite core particles 2 to 9 were obtained under the same conditions as the spherical composite core particle 1 except that the production conditions of the spherical composite core particles were variously changed. Table 2 shows the specifications of the obtained spherical composite core particles.

[0268] Table 3 shows various characteristics of the obtained spherical composite core particles 2 to 9.

[0269] [Table 2]

[0270]

[0271] [table 3]

[0272]

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Abstract

The present invention relates to: a magnetic carrier for electrophotographic developers which comprises spherical composite core particles that comprise fine ferromagnetic iron oxide particles and a cured phenolic resin and that have an average particle diameter of 20-60 µm, wherein (sigma1-sigma0) is in the range of -2 to 0, where sigma0 is the saturation magnetization (Am2 / kg) of carrier particles that have a particle diameter approximately equal to the average particle diameter of the magnetic carrier for electrophotographic developers and sigma1 is the saturation magnetization (Am2 / kg) of carrier particles having a particle diameter smaller than 20 µm; and a two-component developer obtained using the magnetic carrier. This two-component developer comprises a toner and a magnetic carrier for use in electrophotographic developers which have durability, cause no carrier adhesion, and enable long-term formation of high-quality images.

Description

technical field [0001] The present invention provides a magnetic carrier for an electrophotographic developer used in an electrophotographic developer that is durable, does not adhere to a carrier, and can maintain a high-quality image for a long period of time, a method for producing the same, and a magnetic carrier having the magnetic carrier for an electrophotographic developer and A two-component developer for toners. Background technique [0002] As is well known, in electrophotography, a photoconductive substance such as selenium, OPC (organic semiconductor), a-Si, etc. is used as a photoreceptor, and an electrostatic latent image is generally formed by various methods, and the latent image is developed using a magnetic brush method. etc., a method of developing a latent image by attaching a charged toner opposite in polarity to the latent image by electrostatic force. [0003] In this development process, a two-component developer consisting of toner and carrier is u...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G03G9/107G03G9/113
CPCG03G9/1131G03G9/1133G03G9/1137G03G9/107G03G9/1075G03G9/1135G03G9/1136G03G9/108
Inventor 木下香栗田荣一
Owner TODA IND
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