JP2982337B2 - Toner for developing electrostatic images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developing toner used in the field of electrophotography and the like. More specifically, the present invention relates to a toner for developing an electrostatic image, which has a good charge stability of a toner in a developing tank, a small change in image density and an excellent durability.

[0002]

2. Description of the Related Art Conventionally, as a developer for developing an electrostatic image formed on a latent image holding surface such as an electrophotographic photosensitive member, a two-component developer comprising a carrier and a toner and a carrier are used. One-component developers that do not require are known.

[0003] Toner particles constituting these developers are usually colored fine particles containing a resin, a colorant and the like as components.

[0004]

When a developer comprising these toner particles is repeatedly used in a plain paper copying machine or the like, there is a problem that the amount of triboelectricity of the toner increases and the image density of a copy decreases. is there. As an attempt to remedy these drawbacks, there has been known a method of adding a small amount of a conductive fine powder of a metal, a metalloid, or an oxide thereof as an external additive to a toner.

[0005] These substances have a role of suppressing an increase in the amount of charge of the toner particles and always maintaining the image density at a stable level. However, these metals and metalloids and their oxides have an excessively strong polishing action, which may cause unnecessary wear of the photoconductor when cleaning the toner. That is,
Problems such as streak-like polishing scratches caused by conductive fine powder on the surface of the photoreceptor cause image defects, and the film thickness of the photoreceptor becomes severe and the electrical or optical performance of the photoreceptor deteriorates there were. In addition, there is a problem that these conductive substances are sometimes transferred onto paper and a copy image is contaminated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the conventional toner. It is an object of the present invention to provide a method for charging a toner during repeated use without unnecessary wear of a photoreceptor. Without increasing the volume,
That is, it is an object of the present invention to provide a toner for developing an electrostatic charge image that maintains a constant image density without lowering the image density and does not cause contamination of a copy image.

Another object of the present invention is to easily and quickly produce a toner for developing electrostatic images having the above-mentioned advantages.

[0008]

The toner for developing an electrostatic image of the present invention for achieving the above object contains at least a binder resin, a colorant, and a charge control agent, and the charge control agent has a volume The conductive fine particles adhere to at least a part of the charge controlling agent by being mechanically mixed and stirred with conductive fine particles having a specific resistance of 10 ⁹ ohm · cm or less and / or
Or, it is characterized by being fixed.

That is, the gist of the present invention is not to add a conductive fine powder or a fine powder having a polarity opposite to that of a charge control agent to a toner as an additive, but to directly add a charge to the charge control agent itself. And / or fixation of the fine particles, whereby the charging ability of the charge control agent can be always kept constant, and the image density can be remarkably kept stable for a long period of time. The problem of deterioration due to excessive polishing was also solved.

Known charge control agents are used. For positive charging, for example, nigrosine dye, quaternary ammonium salt, polyamine resin and the like can be used. For negative charging, metal-containing azo dyes such as Cr, Co and Al, and metal complex compounds of alkyl salicylic acid can be used.

If the conductive fine particles which adhere and / or fix at least a part of the surface of the charge control agent have a volume resistivity of 10 ⁹ ohm · cm or less, metals, metalloids and their oxides and composite oxides There is no problem even if they are used in various combinations, and there is no problem even if the surface of the oxide is made conductive. These are appropriately selected depending on the type, particle size, shape and the like of the charge control agent.

Specific examples of the conductive fine particles usable in the present invention include oxides such as carbon, titanium black, tin oxide and iron oxide; metals such as gold, copper, iron and aluminum; Conductive titania, conductive silica, conductive zinc, and the like.

The method of adhering and / or fixing the conductive fine particles on the surface of the charge controlling agent in the present invention is a method of mixing and stirring the charge controlling agent and the conductive fine particles by mechanical means, and then, if necessary, reducing the impact force. Adopt the method of giving the main mechanical thermal energy. For mixing and stirring, a commercially available mixer or a high-speed flow stirrer such as a chemical mixer, a super mixer, a Henschel mixer, or a ball mill can be used. Further, as a method for further fixing conductive fine particles, a mechanofusion system, a nara hybridization, A system, a fluidized drying oven, a hot air treatment device, or the like can be used.

The method of attachment and / or fixation by these mechanical means improves the performance of the apparatus and, compared with other dry methods such as vacuum deposition and sputtering, and wet methods such as electroless plating, etc. There is an advantage that processing can be easily performed in a short time. Further, in the vacuum deposition method, etc., usable substances are limited due to the limit of melting temperature, and in the wet method, there are restrictions such as using a chloride of the substance as an initial raw material. The adoption of this method, which is possible only by doing so, expands the selection range of usable charge control agents and conductive fine particles.

The amount of the fine particles deposited on the surface depends on the type and shape of the charge control agent serving as a nucleus and the type of the conductive particles to be attached. 1 to 50 wt%, preferably 1 to 30 w
t% is good. If the amount is too small, the effect cannot be exhibited, and if it is too large, the charging ability itself will be lost. The binder resin can be selected from a wide range including known ones, for example, a styrene resin, an epoxy resin,
Examples thereof include a polyester-based resin and a mixture thereof.

As the colorant, for example, known organic pigments and dyes such as phthalocyanine blue and dialyzin red, as well as inorganic pigments such as carbon black, TiO ₂ and red iron oxide, and dyes and pigments for full-color toner can be used.
The amount used is preferably 10 parts by weight or less based on 100 parts by weight of the binder resin. A one-component magnetic toner contains a magnetic compound such as magnetite or ferrite, but the amount of the magnetic compound used is 3% of the total weight.
0 to 50 wt% is good.

In the toner for developing electrostatic images of the present invention,
The charge controlling agent for attaching and / or fixing the conductive fine particles is added in an amount of 7 parts by weight or less, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the binder resin. A general method for producing a toner is performed as follows. Resin, colorant, charge control agent, etc. are evenly dispersed with a Henschel mixer, etc., and this dispersion is kneader, extruder,
Melt and knead with a roll mill. This is a hammer mill,
After coarsely pulverized by a cutter mill or the like, finely pulverized by a jet mill, an I-type mill or the like. Further, the finely pulverized material is classified by a dispersion classifier, a zigzag classifier or the like. Thereafter, if necessary, silica or the like is dispersed in the classified material using a Henschel mixer or the like.

The carrier used in the two-component developer in combination with the toner for developing an electrostatic image of the present invention includes iron powder having an average particle size in the range of 20 to 200 μm,
Ferrite powder, magnetite powder, magnetic powder resin dispersion carrier, and the like can be preferably used. Iron powder, ferrite powder,
The magnetite powder or the like may be a coating carrier whose surface is coated with a resin or the like. The mixing weight ratio of the carrier and the toner is preferably 100: 1 to 10.

[0019]

EXAMPLES The present invention will now be described with reference to specific examples, but the present invention is not limited to these examples.

In the examples, "parts" means "parts by weight".

Example A charge controlling agent adhered to and / or fixed to the surface of conductive fine particles was prepared by the following method.

Charge control agent (1): Chromium-containing azo dye S
-34 (manufactured by Orient Chemical Co.) was applied with Fe ₃ O ₄ on a surface of 10 wt% using a chemical mixer. Charge control agent (2): Conductive titania was fixed on the surface of 20 wt% of nigrosine dye N-04 (manufactured by Orient Chemical Co., Ltd.) using a palladium hybridizer.

Charge control agent (3): Fe ₃ O ₄ was fixed to a surface of 10 wt% on a chromium alkyl salicylate complex E-81 (manufactured by Orient Chemical Co., Ltd.) using a palladium hybridizer. Charge control agent (4): Conductive zinc oxide was adhered to a surface of 5 wt% on a chromium alkylsalicylate complex compound E-84 (manufactured by Orient Chemical Co.) using a Henschel mixer. <Example 1> Styrene-based resin 100 parts Carbon black MA-8 8 parts (manufactured by Mitsubishi Kasei) Charge control agent (1) 2 parts Polypropylene wax 2 parts Viscol 550P (manufactured by Sanyo Kasei) After kneading and cooling, the mixture was coarsely pulverized using a hammer mill, and then finely pulverized by a pulverizer using an air jet method. The resulting fine powder was classified to select a particle size of 5 to 20 μm to obtain a toner.

To 4 parts of the toner, 96 parts of a carrier (ferrite powder having a particle diameter of about 100 μm coated with a silicon resin) was mixed with a V blender to prepare a developer. Using this developer, a continuous copying test using a commercially available dry copying machine using selenium as a photoreceptor was performed. As a result, a clear image with no image density reduction was obtained even after 40,000 sheets, and excellent durability was obtained. Was found to have.

The charge amount of the toner in the developer by the blow-off method is -20.3 μC / g at the initial stage and-after 40,000 sheets.
It was 21.5 μC / g.

Comparative Example 1 A toner was produced in the same manner as in Example 1 except that the charge control agent (1) was changed to the chromium-containing azo dye S-34. Hereinafter, a continuous actual photographing test was performed by the same operation as in Example 1. However, the image density was reduced after 10,000 sheets.
The charge amount of the toner in the developer by the blow-off method is −26.2 μC / g at the initial time and −26.2 μC after 10,000 sheets.
C / g.

<Example 2> Styrene resin 100 parts Carbon black # 40 5 parts (manufactured by Mitsubishi Kasei) Charge control agent (2) 2 parts Polypropylene wax 2 parts Viscol 550P (manufactured by Sanyo Chemical) In the same manner as in Example 1, a toner was produced.

A carrier (a ferrite powder having a particle diameter of about 100 μm coated with a fluororesin) is added to 5 parts of the toner.
95 parts were mixed with a V blender to prepare a developer. Using this developer, a continuous actual copying test was performed using a commercially available dry photocopier using an organic photoconductor as a photoreceptor. As a result, it was possible to obtain a clear image with no image density reduction even after 30,000 copies. It was found to have durability.

The charge amount of the toner in the developer by the blow-off method is +24.1 μC / g initially and +2 after 30,000 sheets.
It was 2.8 μC / g.

Comparative Example 2 A toner was prepared in the same manner as in Example 2 except that the charge control agent (2) in the toner composition of Example 2 was changed to the nigrosine dye N-04. Hereinafter, a continuous actual photographing test was performed by the same operation as in Example 2, but the image density was reduced after 8000 sheets. The charge amount of the toner in the developer by the blow-off method is initially 22.9 μm.
It was +28.4 μC / g after 8000 sheets in C / g.

<Example 3> Styrene resin 100 parts Carbon black MA-8 8 parts (manufactured by Mitsubishi Kasei) Charge control agent (3) 1 part Polypropylene wax 2 parts Viscol 550P (manufactured by Sanyo Chemical) A toner was produced in exactly the same manner as in Example 1.

In the following, a continuous real-photographing test was conducted in exactly the same manner as in Example 1, and it was found that a clear image with no image density reduction was obtained even after 30,000 copies, and that excellent durability was obtained. . The charge amount of the toner in the developer by the blow-off method was −18.1 μC / g at the initial stage and −20.1 μC / g after 30,000 sheets.

Comparative Example 3 In the toner composition of Example 3, the charge control agent (3) was replaced with a chromium alkyl salicylate complex E-
A toner was prepared in exactly the same manner except that the toner was changed to 81.
Hereinafter, a continuous actual photographing test was performed by the same operation as in Example 3, but the image density decreased after 10,000 sheets.

The charge amount of the toner in the developer by the blow-off method is initially -22.4 μC / g, and -2 after 10,000 sheets.
It was 7.3 μC / g.

Example 4 100 parts polyester resin 5 parts anthraquinone dye 5 parts (CISolvent Red 52) Charge control agent (4) 2 parts A toner was prepared in exactly the same manner as in Example 1 except for the above composition.

In the following, a continuous real-photographing test was conducted in exactly the same manner as in Example 1. As a result, it was found that even after 30,000 copies, excellent durability was obtained in which clear images could be obtained with no deterioration in image density even after copying. did. The initial charge amount of the toner in the developer by the blow-off method is -14.6 μC / g.
After 30,000 copies, the value was −16.1 μC / g.

Comparative Example 4 A toner was produced in the same manner as in Example 4 except that the charge control agent (4) in the toner composition of Example 4 was changed to the chromium alkylsalicylate complex compound E-84. Hereinafter, a continuous actual photographing test was performed by the same operation as in Example 4, but the image density decreased after 3000 sheets.

The charge amount of the toner in the developer by the blow-off method is −19.6 μC / g at the initial stage and −2 after 3000 sheets.
It was 7.4 μC / g.

[0039]

As described above, the toner for developing an electrostatic image of the present invention can stably maintain the charging ability of the direct charge controlling agent, so that the image density can be stably maintained for a long period of time. Further, the photosensitive member is not unnecessarily worn as in the method for stabilizing charge by adding an external additive. Therefore, if the toner for developing an electrostatic image of the present invention is used, a developing method having high durability over a long period can be obtained.

As a method for attaching and / or fixing the conductive fine particles to the charge controlling agent, a means for mechanically mixing and stirring is used, so that the treatment can be performed easily in a short time and the charge control agent can be applied over a wide range. An agent and conductive fine particles can be appropriately selected and used.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hirofumi Oda 370, Enzo, Chigasaki-shi, Kanagawa Mitsubishi Gas Corporation Chigasaki Office (56) References JP-A-2-79053 (JP, A) JP-A-59- 123848 (JP, A) JP-A-58-1158 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/097

Claims (1)

(57) [Claims] 1. An electrostatic image developing toner containing at least a binder resin, a colorant and a charge control agent, wherein the charge control agent and the charge control agent have a volume resistivity of 10 ⁹ ohm.
-Electrostatic image development characterized in that the conductive fine particles are attached and / or fixed to at least a part of the charge controlling agent in advance by mechanically mixing and stirring conductive fine particles of not more than cm. For toner