JPS61260255A - Electric charge material for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To obtain an electric charge providing material which donates adequate negative electric charge to a toner by incorporating a specific compd. into at least the surface of said material. CONSTITUTION:This material has the compd. expressed by the formula at least on the surface. (In the formulas, R1 denotes an aryl group R2, R3 denote a hydrogen atom, halogen atom, alkyl group, amino group, alkoxy group, acyl group, nitro group and aryl group.) Such compd. is exemplified by the compds. expressed by formula (1), formula (2). The compds. is preferably used in the form of particles having generally 10-0.01mum, more particularly 2-0.1mu average grain size for the electric charge providing material although the grain size varies with the form of the charge providing material. General resins are usable for the binder resin or molding resin to be used together with the compd. and is preferably used at such a ratio by weight at which the compd. is incorporated at 0.5-200pts., more particularly 2-100pts. in 100pts. said resin.

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゜297.89
1, Special Publication No. 42-23910, and Special Publication No. 43
Various methods are described in Japanese Patent No. 24748, etc., but in short, these methods involve applying a uniform electrostatic charge onto a photoconductive insulating layer and irradiating the insulating layer with a light image. An electrostatic latent image is formed, and then this latent image is developed and visualized using a fine powder called toner in this technology. After transferring the powder image to paper etc. as necessary, it is transferred by heat, pressure, or solvent vapor. This is to fix the problem.

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. Two-component developing methods include a magnetic brush method using an iron powder carrier, a cascade method using a 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, in which toner particles are brought into direct contact with the electrostatic latent image surface for development. (also referred to as toner development), a 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; There is the MagneDry method, which develops by bringing a conductive toner into contact with the electrostatic latent image surface.

Toners applicable to these development methods include:

Conventionally, fine powders in which dyes and pigments are dispersed in natural or synthetic resins have been used.For example, powders in which colorants are dispersed in binder resins such as polystyrene are used.
Finely pulverized particles 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 must be present on the surface of the toner to some extent. Therefore, these additives 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 the carrier, etc., and contamination of the electrostatic latent image carrier, such as the photoreceptor belt or drum, etc. occur. As a result, the charging property deteriorates, and as development operations are repeated, the 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 problems can be improved by improving the compatibility and dispersibility of the toner binder with 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 developing process.

It has also been proposed to improve the charge imparting characteristics to the toner by imparting a charge necessary for development to the toner or a material or member capable of imparting an auxiliary charge to the 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 an electrostatic image according to the present invention, which has been made to preferably achieve the various objects described above, is characterized by a compound represented by the following chemical structural formula (wherein R1 is an aryl group, R2 and R3 each have a hydrogen atom, a halogen atom, an alkyl group, an amino group, an alkoxy group, an acyl group, a nitro group, or an aryl group on at least the surface thereof.

Typical specific examples of compounds used in the charge-imparting material of the present invention include the following compounds (1) to (8).

H (8).

I H3 , these compounds are synthesized by known methods.

That is, a THF solution of catechol is added dropwise to a solution of poran in tetrahydrofuran (THF) while stirring without raising the temperature above 0° C. to obtain dicatecholborane.

Next, add the corresponding THF solution of guanidine to obtain guanidine dicatechol borate. The compound is
Although it depends on the form of the charge imparting material to be applied, it is generally preferable to use particles with an average particle diameter of 10 to 0.01 p, particularly 2 to 0.1 u, to form the 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,
Coating by Hega-coating or the like, or if the base material is in the form of carrier particles, mixing it with the above coating liquid by dipping and then drying it, or coating with a fluidized bed of a direct mixture of this and the above compound. The charge-imparting material of the present invention can be obtained by forming a coating layer of the compound on the base material by the method described above. Alternatively, the charge imparting material may be directly melted and kneaded with a binder resin and extruded and laminated onto a base material to obtain a charge imparting material having a coating layer containing the material.Further, these compounds may be contained in a moldable resin. 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 used6, such as 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/cm'', preferably 0.1 to 2 B/c.

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. Further, 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.

All known carriers can be used as the base material for the charge imparting material in carrier form.

Powder or particles of metals or alloys such as iron, nickel, aluminum, copper, or metal compounds containing metal oxides, as well as glass, Sin, BaTiO2,
Ceramic powder or particles such as 5rTi02 are used. Further, examples include those whose surfaces have been treated with a resin, resin powder, or resin powder containing a magnetic material. Average particle size is 20~
Approximately 2501 parts is suitable.

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

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. That is, both non-magnetic and magnetic toners can be used. More specifically, the toner is a colored fine particle containing a colorant in a binder resin, and if necessary,
Furthermore, these toners may contain magnetic powder for more effective charging.

It may contain small amounts of charge-imparting substances, such as dyes, pigments, or so-called charge control agents, as well as fluidizing agents such as colloidal silica, abrasives such as cerium oxide, strontium titanate, silicon carbide, and metal stearates. It may contain lubricants such as salts and vinylidene fluoride, and 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 the present invention, there is provided a charge imparting material for imparting a charge to a toner for developing an electrostatic image, in which a compound having a specific structure as a charge control agent is present on one 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 provided. Therefore, by using this charge-imparting material, it is possible to obtain a physical 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 The above compound (
1) was dissolved and dispersed, 1 kg of iron powder carrier (particle size: 250 to 400 meh) was dispersed therein, and the mixture was stirred in a ball mill for about 30 minutes.

After drying this iron powder carrier mixture and completely removing 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 Thiben 3500, manufactured by Capot Co., Ltd.) The above materials were mixed, crushed, and classified to have a particle size of 1 to 30 lm.

This toner and each of the above carriers were mixed in a heavy electric ratio of 10:100.
This was mixed to prepare a developer.

The amount of triboelectric charge of these developers was measured using the blow-off method, and the results were as follows: Comparative product
-2 Minato C/g When images were produced using a Canon NP-5000 copying machine using these developers, the product of the present invention yielded 50.0
Even in a durability test of 00 sheets, there was no change in image density, and the fine line reproducibility was good and the single gradation property was also good. There was also no fog. On the other hand, the comparative product showed a change in image density after 3,000 sheets.

Example 2 Polymethyl methacrylate resin 100 in xylene 11
g was dissolved, and 50 g of compound (2) 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 amount of triboelectric charge of the toner was -12 gC/g, and when an image was formed using this, the resulting image was 50 gC/g.
Even in a durability test of ,000 sheets, the image density remained as good as the initial image density, fine line reproducibility, and single gradation, and there was no fog.

Example 3 Polymethyl methacrylate resin 100 in xylene 11
A solution was prepared by dissolving 50 g of compound (3). A developing sleeve (made of stainless steel) for Canon NP-400RE was dipped in this solution, and the sleeve was coated at 0.1 to 0.8 mg/c.

In addition, in order to compare with the product of the present invention, a comparative product sleeve was prepared without adding compound (3) in the above procedure.

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

Poly(styrene-butyl methacrylate)) 100 parts 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.)
The toner produced in 80 copies had a particle size of 1 L to 30 IL.

Using this toner, an image reproduction durability test was conducted using Canon MP-40QRE. 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, in the comparison product, a change in image density occurred between a and ooo sheets.

Further, when the surface potential on the sleeve was measured, it was -27V for the product of the present invention (Example 3) and -7V for the comparative product, confirming that the toner in the product of the present invention was completely negatively charged.

Example 4 80 g of polycarbonate resin was dissolved in 1R of xylene, and 20 g of the compound (0) was further mixed.
Dip the developing sleeve (made of aluminum) of the developing machine of the -20 blue cartridge, and place 0.1
~0.5 mg/cr1f(7): Shut down.

This sleeve was placed in the original developing machine.

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

100 parts of poly(styrene-butyl methacrylate)? 1
11w = 150.000 Mold release agent (trade name PE-130: manufactured by Hoechst) 4
Section Blue colorant (phthalocyanine pigment) Section C 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, the image does not change 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 25V and was negatively charged.

Examples 5 to 8 Examples 5 to 8 were carried out in accordance with the procedures of Examples 1 to 4, with the respective compounds used in Examples 1 to 4 being replaced as shown below.

Compound (1)→(5) Example 5 〃(2)→(13) tt 5 〃(3)→(7) tt 7 〃 (0→(9) // 8 The results are good, The correspondingly measured triboelectric charge amount and surface potential were as follows.

Example 5 -8.2 final C/g tt 6 -9.31Lc/g//7 -
41V //8 -33V

Claims (4)

[Claims] (1) Compounds represented by the chemical structural formula below ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R_1 is an aryl group, R_2 and R_3 are hydrogen atoms, halogen atoms, alkyl groups, amino groups, alkoxy groups, 1. A charge-imparting material for developing electrostatic images, characterized in that it has at least an acyl group, a nitro group, or an aryl group on its surface. (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.