JPS59111155A - Electrophotographic ferrite carrier - Google Patents

Abstract

PURPOSE:To obtain a spherical electrophotographic ferrite carrier having long life and high electric resistance and forming an image superior in sharpness, etc. by heat-treating a ferrite contg. Fe2O3 as an essential component and SrO and ZnO in a specified molar ratio. CONSTITUTION:Starting materials are weighed and mixed to obtain a ferrite composed of 5-30mol% SrO, 5-30mol% ZnO, and 50-90mol% Fe2O3, or a ferrite having a part of this compsn. substd. by a monovalent or higher valent metal, such as MnO. This powder mixture is calcined, pulverized, granulated, burned at 1,100-1,400 deg.C, and finally heat-treated at about 700 deg.C for about 2hr in a nitrogen atm. to obtain the intended electrophotographic ferrite carrier. The obtained ferrite carrier has 10<2>-10<13>OMEGA-cm resistivity, >=10emu/g saturation magnetization, >=10mu magnetic permeability, >=100 deg.C Curie. temp., and >=1,000g/ cm<2> particle strength.

Description

[Detailed description of the invention] The present invention is a toner kittoria for photo printing. There is noku.

The development method for electrophotography is the cascade development method.

The magnetic brush development method is dead! There is this method, but the characteristics required for chitria are that it has appropriate triboelectrification properties and attracts 1/2 particles, is dense and has sufficient particle strength so that it does not cause particle destruction. The particles must be rich in 〉18 motion ↑'1-, the particles must be uniform, the surface condition must be stable without changing various properties due to stress, etc., and the particles must have tensile and compressive strength. Appropriate saturation magnetization, transparent)
For example, φ has a coefficient or coercivity no. In particular, electrical resistance is closely related to triboelectric charging, and both I! ! It is known to have a significant effect on human characteristics.

Conventionally, various materials have been used for 1-Narchitria particles, but the most commonly used material is iron powder horn. surface of iron powder) i! Although it is used with a fair texture, if it is used for a long time, the surface of the particles may change physically or chemically, and particles may adhere to it, or the humidity of the used 1'8' HA may change. The drawback is that it is sensitive to light and the sharpness of both edges is obscured, and its lifespan is short.

In addition, the use of ferrite, which is a good magnet for acid IL materials, as chitria was reported in 1987, '13 G.
etc. (reported, but conventional) T-light chytria are not always satisfactory in terms of image properties or lifetime.

The present invention enables printing fii by arbitrarily changing electrical resistance.
The purpose of the present invention is to provide a toner carrier having an increased f1 degree, eliminating the drawbacks of conventional toner carriers for electrophotography, and having excellent toner carrier properties and long life.

According to the present invention, the electrical resistivity is preferably 102 ΩCm or higher; outside this range, the amount of triboelectric charge cannot be controlled properly and is susceptible to the effects of 9 degrees, etc., and the desired clear image cannot be obtained. That is difficult. Also, the value of saturation magnetization is 10
emlJ/! ] or more is appropriate, and if it is smaller than this l+j'f, the absorption force saving with the magnetic roll will decrease and the target value is m
It is difficult to obtain a clear image.

Moreover, if 1-1G is 1000a or more, the particles themselves have magnetic properties and adhere to various parts, making it impossible to obtain good images. Furthermore, if the magnetic permeability μ is less than 10, the response to the magnetic roll will be poor and the image quality will be affected.

This will be explained in detail below using examples.

Example [Magnetization rsr020%, Zn020%lFe20360
% and mixed by hanging on a scale.

As a mixer, a ball mill, a vibration mill, a mixer, etc. were used. The mixed powder was calcined at 800 to 1200°C. The calcined samples were processed using a ball mill or a vibration mill.

It was pulverized using a pulverizer such as Attritor. The particle size after pulverization was measured using an air permeation method, and the average particle size was 0.3.
It was ~2.0μ.

The crushed trial 1 was used as a binder. V. P: Use an aqueous solution of A (polyvinyl alcohol).

V. A no fii to LT ha 0.05-5, OWi%)
The granules were granulated using a 3S granulator such as , Suf L'-Try A7-, Kneader, and Mikily.

Next, the granulated powder was fired at 1100°C. As for the firing method, the granules may be placed in a container made of alumina or the like and then fired, but if the powder is placed in multiple towers and fired, the grains may grow during firing and the grains may join together. Therefore, the sample may be fired while rotating in a rotor kiln or the like.

Next, heat treatment was performed at 700°C for 2 hours in a nitrogen atmosphere. The properties of the ferrite thus obtained are shown in Table 1.

Table 1: Using this spherical ferrite as the toner key 1/rear,
As a result of copying, the conventional iron powder kitria is approximately 10,000
70,000-ioo, by using the main 11 rear of the present invention for 50,000 sheets of Ferrai 1 to carrier.
.

00 clear copies were possible.

Example 2 Molar ratio rSr07%, Zr023%. Mn03%.

A spherical ferrite having essentially the same characteristics was produced by weighing the product to have 02% Cu and 65% Fe2Q, and subjecting it to the same treatment as in Example 1. As a result of a copying test using this spherical ferrite with a ferrite key 1/rear, the same copying performance as in Example 1 was obtained.

In the present invention, it is desirable that the composition range from Ferray 1 to obtain good image characteristics as a carrier is as follows. That is, the molar ratio of BaO or SrO is 3-3
0%, Fe20a is preferably 50 to 90%, and monovalent or divalent metal oxides, or monovalent and divalent metal oxides, and monovalent and divalent or higher valent metal oxides are all preferably 40% or less. If monovalent or divalent metal exceeds 40% of the base composition shown above, clear images cannot be obtained.

Claims (1)

[Claims] 1. S r 05% to 30% in molar ratio, ZnO 3%.
~30%, [C20350%-90% or a part of the composition is replaced with one type of total bending of monovalent number -1 or 2 seconds or more] 1 light will be heat-treated, Electrical resistance 10
The characteristic is that it has been improved to 2.~1013Ω-cm.
X-shaped electrophotographic flywheel 1-kit rear. 2. Special crystal '1 An electrophotographic fly 1 to Kikame rear characterized in that it has a saturation magnetization of 108 mu/(] or less in the product described in claim 1. 3. Patent Claim 1] In the thing described in l'1,
Ferrite chitria for electrophotography, characterized by a magnetic permeability of μm0 or more. 4. The fly for electrophotography according to claim 1, characterized in that the temperature TO of the electrophotographic material is 100° C. or higher. 5.1 temple t! [In the item set forth in claim 1,
A ferrite carrier for electrophotography, characterized in that the strength of particles is 1000 g7cm2 or more. 61H1 0-
A ferrite for electrophotography, Kyocyria, which is characterized by oxidizing the surface of the particles. 7. Particular i' (J3 according to claims 1 to 5), characterized in that the surfaces of the particles are coated with a resin or the like.