JPS61259264A - Charge providing material for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To obtain a charge providing material capable of providing proper electric charges to a toner and forming an excellent image by holding a Ce compound on at least the surface of a charge providing material such as carrier particles for providing electric charges to a toner in an electrophotographic process. CONSTITUTION:A Ce compound such as Ce(CH3COO)3.H2O as a charge controller or the compound and a resin binder such as polystyrene are dissolved in a solvent or dispersed in a dispersion medium to prepare a coating liq. A charge providing material such as carrier particles, a sleeve or a doctor blade used to provide electric charges to a toner which develops an electrostatic charge image is dipped in the coating liq. or coated with the liq. and dried to hold the Ce compound on the surface of the charge providing material. The charge controller is stable to heating and moisture absorption and withstands friction with a toner, so a charge providing material having superior durability is obtd.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides an improved function for imparting charge to toner used for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc. Related to materials or members.

[Background of the invention]

Conventionally, as an electrophotographic method, U.S. Patent No. 2゜297.6
91, Special Publication No. 42-23910, and Special Publication No. 4
Various methods are described in Japanese Patent No. 3-24748, etc., but they basically involve applying a uniform electrostatic charge onto a photoconductive insulating layer and irradiating the insulating layer with a light image. to form an electrostatic latent image, and then this latent image is developed and visualized using fine powder called toner in this technology, and if necessary, after transferring the powder image to paper etc., heating, pressurization, solvent vapor, etc. Fixation is carried out by

The developing methods applied to these electrophotographic methods include:
Broadly speaking, there are dry development methods and wet development methods. The former is further divided into a method using a two-component developer and a method using a -component developer. The two-component developing methods include a magnetic brush method using iron powder or carrier, a cascade method using bead carrier, a fur brush method using fur, etc., depending on the type of carrier for conveying the toner.

In addition, methods belonging to the -component development method include the powder cloud method, in which toner particles are sprayed, and the contact development method (contact development, or toner development method, in which toner particles are brought into direct contact with the electrostatic latent image surface for development. Jumping development method, in which toner particles are not brought into direct contact with the electrostatic latent image surface, but are charged and flown toward the latent image surface by the electric field of the electrostatic latent image; magnetic conductivity; There is the MagneDry method, which develops by bringing toner into contact with the electrostatic latent image surface.

As toners applied to these developing methods, fine powders in which dyes and pigments are dispersed in natural or synthetic resins have conventionally been used, for example.

Particles obtained by dispersing a colorant in a binder resin such as polystyrene and pulverizing the particles to about 1 to 30 liters are used as toner. As magnetic toners, those containing magnetic particles such as magnetite instead of or in addition to the dyes or pigments described above are used.

In the case of a system using a so-called two-component developer, the above toner is usually mixed with carrier particles such as glass beads and iron powder.

Further, the toner is given a positive or negative charge in advance depending on the polarity of the electrostatic latent image to be developed.

In order to charge the toner, it is also possible to use only the triboelectricity of the resin that is a component of the toner, but with this method, the toner's chargeability is small, so the image obtained by development is prone to fogging and is unclear. Become something. Therefore, in order to impart desired triboelectric charging properties to the toner, charge control agents such as dyes and pigments that enhance the charging properties are added.

However, in order to impart chargeability to the toner by adding these additives.

These additives and agents must be exposed to a certain extent on the toner surface. Therefore, these additives may fall off from the toner surface due to friction between the toners, collision with the carrier, friction with the electrostatic latent image holder, etc. , contamination of carriers, etc.
Contamination of the electrostatic latent image carrier, such as a photoreceptor belt or drum, may occur. As a result, charging properties deteriorate,
Furthermore, as development operations are repeated, deterioration progresses, resulting in a decrease in image density, a decrease in fine line reproducibility, an increase in fog, and other practical problems.

The above-mentioned problems can be improved by improving the affinity and dispersibility of the toner binder and additives such as dyes and pigments that impart chargeability or charge control agents. Surface treatment to increase the toner often results in a decrease in charge imparting properties, and if mechanical shear is strongly applied and finely dispersed, the proportion of the additive that appears on the toner surface decreases, resulting in a tendency for insufficient chargeability to be imparted. . For these reasons, the number of additives that can impart chargeability to toner to a level that is sufficiently satisfactory for practical purposes is extremely limited, and only a small number of them have been put to practical use. In order to obtain a color image, it is preferable that the charge control agent added to the toner be colorless, and in this case, there are almost no practically satisfactory charge control agents.

In view of these circumstances, the improvement of the charge imparting characteristics to toner is not only achieved by toner additives, but also by improving the conveyance, regulation, or friction of carriers, sleeves, doctor blades, etc. that come into contact with toner during the development process. A member (hereinafter collectively referred to as a "charge-imparting material") that comes into contact with the toner during or prior to the development process, and can impart a charge necessary for development to the toner, or can provide an auxiliary charge to the toner. (collectively refers to materials or parts)
It has also been proposed to improve the charge imparting characteristics to toner.

This method of actively imparting charge to the toner using a charge imparting material eliminates the need for the toner to contain additives to improve charging characteristics, so it is possible to improve the quality of the toner to address the above-mentioned problems. For example, contamination sources such as carrier particles and photoreceptors are reduced in a wood-based manner,
Therefore, repeated development operations do not reduce the charging property or disturb the latent image, and furthermore, the color toner can be easily charged without damaging its tone.

However, charge-imparting materials such as carriers, sleeves, and doctor blades must not only have strong charge-imparting ability, but also be durable and able to withstand friction with toner. For example, carriers must be replaced over a long period of time. In addition, the sleeve is required to have the same degree of durability as the main body of the developing machine.

[Purpose of the invention]

The present invention has been made in order to provide a charge imparting material that solves the above-mentioned problems, and its purpose is to provide a charge imparting material that imparts an appropriate negative charge to toner.

A further object of the present invention is to provide a charge imparting material whose performance does not deteriorate even after long-term use.

A further object of the present invention is to provide a charge-imparting material that provides images with excellent fine line reproducibility and gradation.

A further object of the present invention is to provide a charge imparting material suitable for charging color toners.

[Summary of the invention]

The charge imparting material for developing electrostatic images according to the present invention, which has been made to preferably achieve the above-mentioned various objects, is characterized by having a cerium compound at least on the surface.

Typical specific examples of the cerium compound used in the charge imparting material of the present invention include the following compounds (1) to (6).

(1) Ce (CH2C00h ・H,0(2) C
e (SOa)z (3) Ce (IO3)4 (4) CaF2 (5) Ce(OH)a (8) Ge (NO3)4 The compound used in the present invention is extremely stable and can be prepared by known methods. be synthesized.

For example, compound (1) is produced as follows.

Cerium oxide (Ce02; manufactured by Kishida Chemical Co., Ltd.) 10g
is dissolved in 500 μl of 50% acetic acid aqueous solution while heating, and then water is evaporated on a 75° C. water bath to precipitate cerium acetate.

The above compound generally has an average particle size of 10 to 0.011L, particularly 2 to 0.01L, although it depends on the form of the charge imparting material to be applied.
It is preferable to use the particles as particles of 1 JL to form a charge imparting material.

These compounds can be dissolved or dispersed in a solvent or dispersion medium together with a binder resin if necessary, and then a coating liquid obtained is applied to the base material of the charge imparting material by dipping, spraying,
It can be applied by brushing, etc., or if the base material is in the form of carrier particles, it can be immersed and mixed with the above-mentioned coating liquid and then dried, or it can be coated with a fluidized bed of a direct mixture of this and the above-mentioned compound. By forming a coating layer of the compound on a base material by the method described above, an uninvented charge imparting material can be obtained. Alternatively, the charge-imparting material may be directly melt-kneaded with a binder resin and extrusion laminated onto a base material to obtain a charge-imparting material having a coating layer containing the material. This may be formed into the shape of carrier particles, sleeves, or doctor blades to serve as a charge-imparting material.

As the binder resin or molding resin, common resins can be used. For example, polystyrene, polyacrylic ester, polymethacrylic ester, polyacrylonitrile, rubber resins such as isoprene and butadiene, polyester, polyurethane, polyamide, Epoxy resins, rosins, polycarbonates, phenolic resins, chlorinated paraffins, polyethylene, polypropylene, silicone resins, Teflon, derivatives thereof, copolymers thereof, or mixtures thereof can be used.

After coating or molding, these resins can be made to have a crosslinked structure as necessary to improve the durability of the surface layer of the charge-imparting material.

When a binder resin or a molding resin is used, it is preferable to use the compound in a ratio of 0.5 to 200 parts, particularly 2 to 100 parts, based on 100 parts by weight (the same applies hereinafter).

When coating the surface of the charge imparting material, it is necessary to appropriately control the coating or coating amount of the compound, but
The content of the material is preferably in the range of 0.01 to 10 mg/crn'', preferably 0.1 to 2 mg/crn'.

In addition to the above-mentioned compounds, ceramic powders such as silica powder, aluminum oxide, cerium oxide, and silicon carbide may also be used as fillers, and conductive agents such as carbon black and tin oxide may be used as fillers. Furthermore, in order to prevent the spent toner from being deposited on the sleeve or carrier surface, a release agent such as a fatty acid metal salt, vinylidene fluoride, etc. may be used.

As a base material for charge imparting material in carrier form.

All known carriers can be used, including powders or particles of metals or alloys, such as iron, nickel, aluminum, copper, or metal compounds, including metal oxides;
Furthermore, glass, SiC, BaTiO2, 5rTi02
Ceramic powders or particles such as , etc. are used.

Further, examples include those whose surfaces have been treated with a resin, resin powder, or resin powder containing a magnetic material. The average particle size is preferably about 20 to 250 JL.

Furthermore, the base material of the charge imparting material in the form of a sleeve or doctor blade may be metals or alloys such as iron, aluminum, stainless steel, or nickel, or non-metallic compounds such as ceramics or plastics, which are generally used as the base material for the sleeve or doctor blade. You can use whatever is possible.

On the other hand, as toners to be used in combination with the charge imparting material of the present invention as described above, substantially all toners that have been used as conventional toners for developing electrostatic images can be effectively used. In other words, both non-magnetic and magnetic toners can be used. More specifically, the toner is a colored fine particle containing a coloring agent in a binder resin, and may contain magnetic powder if necessary. In order to
For example, it may contain dyes, pigments, or so-called charge control agents, and fluidizing agents such as colloidal silica,
It may contain abrasives such as cerium oxide, strontium titanate, and silicon carbide, and lubricants such as metal stearate and vinylidene fluoride. It may also contain conductivity imparting agents such as carbon black and tin oxide. .

As the developing method using the charge imparting material and toner of the present invention described above, substantially all developing methods using a two-component developer or a single-component developer can be used.

For example, magnetic brush development method, cascade development method, fur brush development method, so-called microtoning development method using magnetic substance-containing resin powder as a carrier, development method using resin powder as a carrier, so-called jumping development method, or non-magnetic This is a jumping development method that develops toner.

〔Effect of the invention〕

As described above, according to one aspect of the present invention, there is provided a charge imparting material for imparting a charge to a toner for developing an electrostatic image, which has a compound having a specific structure as a charge control agent on its surface. In particular, as shown in the examples below, the compound of the present invention not only has excellent charge control properties and stability against heating and moisture absorption, but also has the ability to be coated or kneaded onto the surface of a charge-imparting material. When present by dispersion or the like, a good charge imparting material with excellent durability when used in friction with toner can be obtained. Therefore, by using this charge-imparting material, it is possible to obtain a substantial improvement over the various problems that occur when the charge-imparting material is mixed only into toner to improve its charging characteristics.

[Embodiments of the invention]

Example 1 100 g of the above compound 1 (1) was dissolved and dispersed in methyl ethyl ketone (MEK) lQ, and an iron powder carrier (
Particle size: 250-400 mesh) 1 kg was dispersed and stirred in a ball mill for about 30 minutes.

After drying this iron powder carrier mixture to completely remove the solvent, light agglomerations were loosened to obtain a carrier-like charge imparting material according to the present invention.

In addition, in order to compare with the product of the present invention, a comparative amount carrier was prepared without adding compound (1) in the above operation.

Separately, a toner was prepared according to the following formulation without adding any charge control agent.

Styrene 100 parts (trade name D-125, manufactured by Esso Chemical Co., Ltd.) Carbon black 6 parts (trade name Raven 3500, manufactured by Capot Co., Ltd.) The above materials were kneaded, crushed, and classified to have a particle size of 1 to 30 ILm.

The weight ratio of this toner and each of the carriers is 10:1.
00 to prepare a developer.

The amount of triboelectric charge of these developers was measured by the blow-off method and was as follows.

Comparative amount -2 C/g When images were produced using a Canon MP-5000 copying machine using these developers, the product of the present invention had a 50.0
Even in a durability test of 00 sheets, there was no change in image density, fine line reproducibility was good, and gradation was also good. There was also no fog. On the other hand, with the comparative amount, a change in image density occurred after 3,000 sheets.

Example 2 Polymethyl methacrylate resin 10 in 1 xylene
0 g was dissolved, and 50 g of a compound (ri) was further mixed therein. This was mixed with the same iron powder carrier as in Example 1 and dried to obtain a carrier having a charge imparting effect.

When this was used in combination with a toner in the same manner as in Example 1, the triboelectric charge amount of the toner was -1 OILC/g, and when an image was formed using this, the obtained image was 5.
Even in a durability test of 0,000 sheets, the image density, fine line reproducibility, and gradation were as good as the initial state, and there was no fog.

Example 3 100% polymethyl methacrylate resin in 1 bottle of xylene
A solution was prepared by dissolving 50 g of compound (1). A developing sleeve (made of stainless steel) for Canon MP-400RE was dipped in this solution, and the sleeve was coated at 0.1 to 0.8 tag/cm'.

In addition, in order to compare with the product of the present invention, a comparative sleeve was prepared in the above procedure without adding compound (1).

These sleeves were placed in the original developing machine. The toner was prepared according to the following recipe using a general kneading and pulverizing method.

Poly(styrene-butyl methacrylate) ioo part Mw = 300,000 Mold release agent (trade name PE-130: manufactured by Hoechst) 4
Magnetic powder (product name BL-200: manufactured by Titan Kogyo Co., Ltd.)
80 copies of the toner were prepared, and the particle size varied from 1w to 30 islands.

Using this toner, an image reproduction durability test was conducted using Canon MP-400RE. After 50,000 sheets of durability, there was no change in the image from the beginning, fine line reproducibility and gradation were good, and there was no fog.

On the other hand, the comparative amount caused a change in image density after 3,000 sheets.

Further, when the surface potential on the sleeve was measured, it was -32V for the product of the present invention (Example 3) -7V for comparison, confirming that the toner of the product of the present invention was completely negatively charged.

Example 4 A solution was prepared by dissolving 80 g of polycarbonate resin in one bottle of xylene and further mixing 20 g of compound (1).

A developing sleeve (made of aluminum) of a developing machine for a blue cartridge for Canon PC-20 was dipped in this solution, and a coating of 0.1 to 0.5 g/c was applied onto the sleeve.

This sleeve was placed in the original developing machine.

On the other hand, a toner was prepared according to the following recipe.

Poly(styrene-butyl methacrylate) 100
Part M praise = tso, oo.

Mold release agent (trade name PE-130: manufactured by Hoechst) 4
Part: Blue colorant (phthalocyanine pigment) Part B: The prepared toner had a particle size of IIL to 30IL.

Using this toner and a developing machine equipped with the above-mentioned sleeve, the PC-20 was modified to enable reversal development.
A durable image was produced.

As a result, there is no change in one image until the toner runs out.
A clear blue image with good fine line reproducibility and gradation was obtained. Furthermore, when we measured the surface potential of the toner on the sleeve, we found that -
It was 28V and negatively charged.

Examples 5 to 8 Examples 5 to 8 were carried out in the same order as in Examples 1 to 4, except that compound (1) used in Examples 1 to 4 was replaced with compound (2). . The results were good, and the correspondingly measured amount of triboelectric charge and surface potential were as follows: Example 5-8 Final Cog tt 6-L2ILC/g //7-35V //8- 32V Examples 9 to 12 Examples 9 to 12 were carried out in the same order as in Examples 1 to 4, except that the compound (1) used in Examples 1 to 4 was replaced with compound (3). carried out. The results were good, and the corresponding triboelectric charge amount and surface potential were as follows.

Example 9 -111LC/g //10-13 Cog //11-38 V/l 12-35 V Examples 13-16 In Examples 1-4, the compound (1) used was replaced with the compound (4) Examples 13 to 16 were carried out in the same order as in Examples 1 to 4, except that . The results were good, and the corresponding triboelectric charge amount and surface potential were as follows.

Example 13-12 cig //14-10 final C/g I115-28V /I 16 -32 V

Claims (4)

[Claims] (1) A charge imparting material for developing an electrostatic image, characterized by having a cerium compound on at least the surface thereof. (2) The charge imparting material for developing an electrostatic image as set forth in claim (1), wherein the charge imparting material is carrier particles. (3) The charge imparting material for developing an electrostatic image as set forth in claim (1), wherein the charge imparting material is a cylindrical sleeve. (4) The charge imparting material for developing an electrostatic image as set forth in claim (1), wherein the charge imparting material is a doctor blade.