JPS58123551A - Electrophotographic developing carrier - Google Patents

Abstract

PURPOSE:To obtain a carrier superior in image characteristics and long in service life, by specifying the components and contents of lithium and nickel oxides and their substituted oxides to be added to iron oxide, and their electrical resistivity, their saturation magnetization value, particle diameter, etc. CONSTITUTION:In a molar composn. of 5-15mol% Li2O, 5-17 mol% NiO, and 70-80mol% Fe2O3, Li2O and /or NiO is partly substituted by >=2 kinds of MnO, MgO, CuO, ZnO, and Al2O3. This ferrite carrier has 10<5>-10<12>ohm.cm resistivity, 45-70emu/g saturation magnetization value, 30-1,000mum average particle diameter, <=1.0Oe coercive force Hc, >=50 magnetic permeability at 1MHz, >=50 deg.C Curie temp. Tc, and 1,000g/cm<2> particle strength. It has a spherical form, and the surface of each particle is oxidized or coated with resin or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic toner carrier. Development methods for electrophotography include cascade development, magnetic brush development, and other methods, but the characteristics required for the carrier are appropriate triboelectric charging properties, and when the toner particles are sucked, they are dense and the particles have sufficient strength. Particles that do not cause particle breakage 5 have high fluidity, are uniform, have stable surface conditions that do not change in various properties due to humidity, etc., and have tensile and compressive strength. Conventionally, various materials have been used as toner carrier particles, such as those having appropriate saturation magnetization, magnetic permeability, or coercive force.

Although it has been used, it is the most commonly used one.

There is iron powder. Appropriately treat the surface of the iron powder.

If you use it for a long time, the surface of the particles may change physically or chemically, causing toner to stick to it, or it may become sensitive to the humidity of the usage environment, causing the image clarity to fade, resulting in a short lifespan. There is a drawback.

Furthermore, the use of ferrite, which is an oxide magnetic material, as a carrier has been reported in JP-A-52-56536, etc. 1. )
However, conventional ferrite carriers are not necessarily satisfactory in terms of image characteristics or lifespan.

The present invention eliminates these drawbacks of the conventional toner carriers for Kameko photographs and provides a carrier with excellent image characteristics and a longer life.

In the present invention, the electrical resistivity is 1011ΩcIIL~1
01 edition Ω is good, but there is a friction zone outside this range! It is not possible to control the lL storm to an appropriate value, and it is easily affected by humidity, etc.
It is difficult to obtain the desired clear image. Further, the appropriate value of saturation magnetization is 45@m$g to 70 emu/g.

If it is smaller, the adhesion force with the magnetic pole will be reduced and it will be difficult to capture a clear image. .

Also, Ha is 1. At ooe or higher, the particles themselves become magnets.

Due to its properties, it adheres to various parts, making it impossible to obtain good images.

Furthermore, if the magnetic permeability μ is less than 50, the response to the magnetic roll will be poor and the image quality will be adversely affected.

This will be explained in detail below using examples.

Example 11 mol ratio: L110 mol 5%, Ni0 10 mol%, Mn0
They were weighed and mixed so that the amounts were 3 mol %, Mg 05 mol %, AtiO 53 mol %, and FθaO+175 mol %. As a mixer, a ball mill, a vibration mill, a mixer, etc. were used.

The mixed powder was calcined at 800-IJOOC. The calcined sample 5 was pulverized using a pulverizer such as a ball mill, vibration mill, or attritor. The particle size after crushing is determined using the air permeation method.

□□Kahei'::″□Average particle size, approximately LO, UmT.

The pulverized sample was dried with a spray dryer using an aqueous solution of p, v, * (borihinyl alcohol) (0 α05-J 5.0 wt% for P, V, A @) as a binder.

The mixture was granulated using a granulator such as a granulator or mixer.

The granulated powder was then fired at 1125C. As for the firing method.

Now, put the granulated powder in a container such as alumina and fire it.

It is also good, but if you are baking a large amount in a container, use yaki.

Grain growth occurs during formation, and grains may join together.

Therefore, the sample may be fired while rotating in a rotor kiln or the like. The ferrite obtained in this way was used as a toner carrier and copied. As a result, the conventional iron carrier produced approximately 10,000 sheets and the ferrite carrier produced 50,000 sheets, but by using the carrier of the present invention, the number of sheets was 7α000 to 10α000. Clear 1. It was possible to make exact copies.

Example 2 Li, 05 mol%, Ni 05 mol%, 0u0 in molar ratio
3 mol%, zn07 mol%, Az=o=3 mol% and Fa
It was weighed so that the amount was 10177 mol%, and spherical ferrite was produced in the same manner as in Example 1. This spherical ferrite is used as toner.

Example of the result of adding a copy test as a carrier.

Copy performance similar to that of 1 was obtained.

As described above, the ferrite carrier of the present invention has been found to have higher resistance and longer life than conventionally used iron powder carriers, and has been shown to be highly effective as a developing material for electronic copying machines, and has been used in many industries. It has great practical value.

Claims (1)

[Scope of Claims] A composition comprising L105 mol% to 15 mol%, Ni0 5 mol% to 17 mol%, and 70 mol% to 80 mol% in L molar ratio. L120 and NiO 181 or 2 lff1 Mn01
Mg0,0uO1ZnO1At,O. Some tI with two or more types of! A spherical ferrite carrier having a saturation magnetization value of 45 emu/gs voemVg and an average particle size of 30 μm to 1000 μm in the converted composition. 2% fr ili In the range of claim 1, the ferrite carrier is characterized in that the coercive force is 1 (oLOOe or less). A ferrite carrier characterized by the above. A ferrite carrier according to claim 1, characterized in that the Curie m TO is 50 C or more. 5. Particular! Scope of Claim 'f' A ferrite carrier according to claim 1, characterized in that the strength of the particles is 1-000 g/ct1 or more. 6. A ferrite carrier according to claims 1 to 5, in which the surface of the particles is oxidized. 7. A ferrite carrier according to claims 1 to 5, characterized in that the surface of the particles is coated with a resin or the like.