JPS63237066A - Carrier for two-component type dry developer - Google Patents

Abstract

PURPOSE:To enable a copy to be made in high fidelity to any original, to reduce the abrasion of a coat film at the time of repeated uses, and to enhance durability as a developer by using TiC and/or MoC as fine conductive particles. CONSTITUTION:The TiC and/or MoC is used as the fine conductive particles and they are high in hardness as the conductive material and superior in abrasion resistance, thus permitting a copy high in fidelity to any original image to be made by adding such particles to the coat film, abrasion to be reduced even at the time of repeated uses, the triboelectrification of the toner to be stabilized, and the durability of the developer to be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carrier used in a dry developer having a two-component mixture of toner and carrier.

A two-component dry developer used in long-distance electrophotography and electrostatic recording consists of a two-component mixture of toner and carrier. In the development method using this type of dry developer, the toner charged by frictional charging with the carrier is conveyed together with the carrier to the electrostatic latent image surface of an electrophotographic photoreceptor, etc., and develops by electrostatically adhering to this. will be carried out. At this time, if the carrier has low electrical resistance, it acts as a developing electrode and tries to hold the charged toner in close contact with the latent image surface.
In particular, it is possible to faithfully copy even linear or wide original images. However, in commonly used carriers, the surface of core particles such as iron powder or glass beads is coated with fluororesin, silicone resin, etc., which have good releasability, in order to improve the triboelectric charging properties of the toner and prevent it from becoming spent. ,
Since the electrical resistance is high and therefore it acts as a developing electrode, it is difficult to faithfully copy linear or wide original images.To solve this problem, Japanese Patent Application Laid-Open No. 56-7565
No. 9 proposes adding carbon as conductive particles to the coating resin.

However, such a coated carrier to which carbon is added is easily worn out, and as a result of repeated use, the coated film is scraped and the triboelectric charging properties of the toner become unstable, making it impossible to withstand long-term use as a developer.

The purpose of the present invention is to not only make it possible to faithfully copy any original image, but also to reduce the amount of abrasion of the coating film during repeated use, thereby stabilizing the triboelectric charging properties of the toner and developing it. An object of the present invention is to provide a carrier for a two-component dry type developer that is designed to improve the durability of the developer.

(2) The two-component dry developer carrier of the present invention is a two-component dry developer carrier in which the surface of the core particle is coated with a resin containing conductive fine particles, and the conductive fine particles are TiC and/or It is characterized by using MoC.

TiC and MoC used in the present invention are known as conductive materials. The present inventors focused on the fact that these materials have high hardness and therefore excellent abrasion resistance, and found that the desired purpose could be achieved by using them as conductive fine particles of a coat carrier. reached.

Examples of the resin used in the coating film of the present invention include acrylic resin, polyolefin, polyvinyl chloride, fluorocarbon resin, polyvinylidene chloride resin, fluororesin, silicone resin, polyamide, phenol resin, polyester, epoxy resin, and amino resin. .

In the present invention, TiC and MoC are used as conductive particles for lowering the resistance of these resins, as described above. The particle size is suitably about 0.01 to 5 μm. The amount of these conductive fine powders to be added varies depending on the electrical resistance of the resin, the state of dispersion of the conductive fine powders, the state of use of the carrier, etc., but it is generally preferred to have a strained part of 2 to 80 parts by weight per 100 parts by weight of the resin.

On the other hand, as the core particles of the carrier, conventionally known particles such as iron powder and glass beads can be used as they are.

The method for producing the carrier of the present invention includes the spray method, fluidized pellet method, etc., as in the past, but is not particularly limited to these methods.

The thickness of the coating film formed by these methods is 0.9
~5μ bile is appropriate.

The present invention will be explained below by way of examples. Note that both parts and percentages are based on weight.

Example 1 A coating liquid was prepared by dispersing a formulation consisting of 50 parts of TiC with an average particle size of 0.2μ and 150 parts of toluene in a homomixer for 30 minutes. A carrier having a coating thickness of about 0.95 μm was prepared by coating the surface using a fluidized bed coating device. The volume resistivity of the obtained carrier was 5×10 10 Ω.

Next, 97.5 parts of this carrier and 2.5 parts of a black toner made of styrene acrylic resin, carbon black, and monoazochrome complex dye were mixed to prepare a two-component dry developer, and the toner charge amount Q/ When M was examined by the blow-off method, it was -18.5 μC/g. Next, this developer was put into a plain paper copying machine (FT-4060, manufactured by Ricoh Co., Ltd.), and when copies were made, very good images were formed. Further, when a continuous copying test of 100,000 sheets was conducted, the Q/M of the toner was -16.5 μc/g, which was slightly lower than the initial value. The coating film thickness at this time was 0.89μ. Also, the carrier in the developer at this point (350
The volume resistivity of the sample (obtained by separating it from the toner using a mesh sieve) was 3×10 11 ΩG, which was slightly higher than the initial value. In addition, the volume resistance of the carrier is the electrode area of 20cn?
, the sample is filled into a cell with an inter-electrode distance of 2ffll, and 1
The measurement was performed by applying a DC voltage of 00V.

Comparative Example 1 A carrier having a coating thickness of about 0.95 μm was produced in the same manner as in Example 1 except that TiC was not used. The volume resistance of this product is 3. I×10”ΩG.

Further, a developer was prepared using this carrier in the same manner as in Example 1, and the charge amount Q/M of the toner was examined.
It was μc/g. Next, when copying was carried out in the same manner as in Example 1 using this developer, the resulting image had unevenness, especially in the wide image area, and was not suitable for practical use.

Also, 07M after 100,000 sheets continuous copying test is -16.5μ
c/g, which was slightly lower than the initial value. The coating film thickness at this time was 0.89μ. Also, the volume resistance of the carrier in the developer at this point was 5.3 x 10"9,
It has increased slightly compared to the initial period.

Example 2 A carrier having a coating thickness of about 0.95 μm was prepared in the same manner as in Example 1, except that MoC (average particle size: 0.2 μm) was used instead of TiC. The volume resistivity of this product was 5×10”Ω■.A developer was prepared using this carrier in the same manner as in Example 1, and the charge amount Q/M of the toner was examined.
It was 18.5 μc/g. Next, when copying was carried out in the same manner as in Example 1 using this developer, an extremely good image was formed. 0 after 100,000 sheets continuous copying test
7M was -16.5 μc/g, which was slightly lower than the initial value. The coating film thickness at this time was 0.89μ.

Also, the volume resistance of the carrier in the developer at this point is 3.
I x 1011Ω■, slightly increased compared to the initial value.

Example 3 A two-component dry developer was prepared in the same manner as in Example 1, except that a yellow toner consisting of a styrene acrylic resin, a yellow pigment, and a chromium alkylsalicylate complex compound was used instead of the black toner. The toner charge amount Q/M of this yellow color developer was -18.5 μc/g. Next, when this developer was used to make copies using a color 5ooo copying machine, very good images were formed. 10 more
07M after the 10,000-sheet continuous copying test was -16.5 μC/g, which was slightly lower than the initial value. The coating film thickness at this time was 0.89μ. Also, the volume resistance of the carrier in the developer at this point is 3. There was a slight increase in I x 1011Ω.

Comparative Example 2 The same method as in Example 1 was used except that carbon (average particle size 0.2 μ) (Ketjen Black EC-DJ600 manufactured by Lion Akzo Co., Ltd.) was used instead of TiC, with a coating film thickness of about 0.95 μm.
I made a μ carrier. The volume resistance of this thing is 5X10
It was a 10Ω mark. Next, 97.5 parts of this carrier and 2.5 parts of the yellow toner used in Example 3 were mixed to prepare a two-component dry developer.

The toner charge amount Q/M of this yellow color developer is -
It was 18.5 μc/g. Next, when copying was carried out in the same manner as in Example 3 using this developer, an extremely good image was formed. Also, after the 10,000-sheet continuous copying test, 07
M was -16.5 μc/g, which was slightly lower than the initial value. The coating film thickness at this time was 0.45 μm, which was extremely thin. Further, the volume resistivity of the carrier in the developer at this point was 5.1×10 12 Ω mark, which was slightly higher than the initial value.

Example 4 A two-component dry developer was prepared in the same manner as in Example 2, except that the yellow toner of Example 3 was used instead of the black toner. The toner charge amount Q/M of this yellow color developer is -
It was 18.5 μc/g.

Next, when this developer was used for copying with a Color 5000 copying machine, very good images were formed. Also, 07M after 10,000 sheets continuous copying test is -16.5μc/
g, which was slightly lower than the initial value. The coating film thickness at this time was 0.89μ.

Also, the volume resistance of the carrier in the developer at this point is 3.
I x 1011Ω-, which increased slightly.

Example 5 A coating liquid was prepared by dispersing a formulation consisting of 50 parts of TiC and 150 parts of methyl ethyl ketone with an average particle size of 0.2 μm in a homomixer for 30 minutes, and this liquid was mixed with 500 parts of oxidized iron powder core particles with an average particle size of 100 μm. using a fluidized bed coating device at 80℃ on the surface of
This was further heated at 200° C. for 2 hours to cure the coated film, thereby producing a carrier having a coated film thickness of about 0.95 μm. The volume resistance of the obtained carrier is 5X1
The resistance was 0.010Ω.

Next, 97.5 parts of this carrier was mixed with 2.5 parts of a black toner consisting of styrene acrylic resin, carbon black, and nigrosine pigment to prepare a two-component dry developer.
When the charge amount Q/M of the toner is examined using the blow-off method, +
It was 18.5 μc/g. Next, when this developer was put into a plain paper copying machine (Ricoh Co., Ltd. 1JFT-7500) and copies were made, very good images were formed. Further, when a continuous copying test of 100,000 sheets was performed, the Q/M of the toner was +16.5 μc/g, which was slightly lower than the initial value. The coating film thickness at this time was 0.89μ.

Also, the volume resistance of the carrier in the developer at this point is 3X
There was a slight increase in 1011Ω countries.

As mentioned above, the coated carrier of the present invention has conductive fine particles added to the coating layer, so that it acts as a developing electrode, and as a result, not only can faithful copying of any original image be made, Since conductive fine particles with excellent abrasion resistance are used, the coating film is less likely to be scratched even after repeated use, thereby stabilizing the triboelectric charging properties of the toner and improving its durability as a developer.

Claims (1)

[Claims] 1. A two-component dry type developer carrier comprising a resin coated with conductive fine particles on the surface of a core particle, characterized in that TiC and/or MoC are used as the conductive fine particles. Carrier for developer.