JPH06214428A - Electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE:To enhance acceptance potential stability, durability, and image stability by using a specified filler, specifying a dye to filler ratio, and incorporating a charge controlling agent in the toner in a specified amount in the manufacturing process of charge controller. CONSTITUTION:The toner comprises at least a binder resin, a colorant, and the charge controller made of a lake pigment obtained by kneading and mixing a rhodamine type dye with the filler in a dye to filler weight ratio of 0.1-1, and the charge controlling agent is added to the binder resin in an amount of 0.05-10 weight % of the binder resin. The filler is embodied by clay, gypsum, zinc white, lithopone, white lead, and the like, and here it is preferred to use one of aluminum hydroxide, barium sulfate, and calcium carbonate. A toner to carrier powder mixing weight ratio is (0.5-10):(99.5-90), preferably, (2-4):(98-96).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic charge image (electrostatic latent image) in electrophotography, electrostatic recording or the like.

[0002]

2. Description of the Related Art Originally, an electrostatic latent image can be visualized by developing it by adhering toner by its electrostatic attraction, but as a developer for this electrostatic latent image, it is dry development other than wet development. Agents are widely used. This dry developer
A toner having an average particle size of 10 to 15 μm in which a colorant, a charge control agent, a fluidizing agent, etc. are dispersed in a natural resin or a synthetic resin, and 10
A two-component developer consisting of a mixture of a carrier such as iron powder or ferrite powder of 0 to 200 μm, and an average particle in which a colorant, a charge control agent, a fluidizing agent, a magnetic material and the like are dispersed in a natural resin or a synthetic resin. It can be roughly classified into a one-component developer composed of only toner having a diameter of 7 to 10 μm.

The two-component type developer achieves the development by adhering the toner charged by friction with the carrier to the electrostatic latent image, and the one-component type developer uses this instead of the carrier. Brush-like, having the same function as
A toner that is charged by friction with a plate-shaped friction member is known, and recently, a toner that is maintained by dispersing magnetic fine powder and charged by mutual friction with the fine magnetic powder is known. There is. Thus, these developing toners hold a positive or negative charge depending on the polarity of the electrostatic latent image to be developed. In order to make the toner retain the electric charge,
It has also been proposed to utilize the triboelectrification property of the resin, which is the main component of the toner, but in this method, the toner chargeability is low and the solid surface resistance value is high, so the resulting image is easily fogged and unclear. It will be

Therefore, in order to impart a desired triboelectric chargeability to a toner, the one which is practically used in this technical field today is a case of imparting a positive charge to the toner.
There are nigrosine-based oil-soluble dyes and the like disclosed in Japanese Patent Publication No. 1-2427, and when imparting a negative charge, Japanese Patent Publication No. 41-20153, Japanese Patent Publication No. 43-17955, and Japanese Patent Publication No. 45- There are metal-containing complex salt dyes and the like as disclosed in Japanese Patent No. 26478.

[0005]

In these charge control agents, the function of simply giving an electric charge is not sufficient, and it is required to control the charge amount of the toner to be constant. It is necessary for the toner to be controlled so that it is always triboelectrically charged to a constant charge amount under any environment and during long-term use, and as a result, it is possible to stably provide a high image quality. Therefore, conventional toners are no longer able to satisfy the above various requirements, and improvement of the charge control agent is required.

Therefore, an object of the present invention is to provide a toner having excellent durability and capable of always obtaining a stable image even when continuously used for a long period of time. Another object of the present invention is to provide a charge control agent which has a fast charge rise and gives a stable and high quality image from the initial stage.

[0007]

According to the present invention, in an electrostatic image developing toner comprising at least a binder resin, a colorant and a charge control agent, the charge control agent comprises a rhodamine dye and an extender pigment. The synthetic pigment is a lake pigment having a ratio (weight ratio) of the dye to the extender pigment in the range of 0.1 to 1, and the charge control agent is 0 based on 100 parts by weight of the binder resin. A toner for developing an electrostatic charge image is provided, which comprises 0.05 to 10 parts by weight.

The electrostatic image developing toner of the present invention will be described in detail below. In the present invention, a laked pigment is used as the charge control agent, and as the constituent components of the pigment, there are a dye, an extender pigment and a precipitating agent, in which the ratio (weight ratio) of the dye to the extender pigment is 0. 1 to
It is characterized in that it is controlled in the range of 1 and the ratio of the charge control agent in the toner is in the range of 0.05 to 10 parts by weight with respect to 100 parts by weight of the binder resin.
The extender pigment includes clay, gypsum, zinc white, lithopone, lead white, etc., but in the present invention, at least one selected from aluminum hydroxide, barium sulfate and calcium carbonate is used as the extender pigment. preferable.

Specific reaction processes for constitution synthesis and lake formation will be described below. As a general reaction mode, a band of sulfuric acid, barium chloride and sodium carbonate are reacted to synthesize aluminum hydroxide and barium sulfate, and rhodamine which is a dye is added thereto to form a constitution. Further, phosphorus, tungsten and molybdic acid are added as a precipitating agent to form a lake, and the precipitate is filtered, washed with water, dried, pulverized and toned to obtain a lake pigment. Stability as a charge control agent can be obtained by adjusting the proportion of the dye in the range of 0.1 to 1 (weight ratio) of the extender barium sulfate and aluminum hydroxide in the above reaction step. Becomes It is presumed that the water content of the lake pigment produced as a product is controlled to be low by increasing the amount of water-insoluble extender pigment, and as a result, the charge stability as a charge control agent can be obtained.

The ratio of the dye to the extender pigment (weight ratio)
If it is less than 0.1, the characteristics as a lake pigment cannot be obtained, and as a result, the charging stability is lost. Further, if the ratio exceeds 1, the constitutional reaction becomes insufficient,
The resulting lake pigment has a large amount of water, and the charge stability as a charge control agent cannot be obtained. Further, the proportion of the charge control agent used in the present invention in the toner is in the range of 0.05 to 10 parts by weight, but less than 0.05 parts by weight, relative to 100 parts by weight of the binder resin. However, it is difficult to obtain the charge stability and the charge rising property, which are the objects of the present invention. On the contrary, if it exceeds 10 parts by weight, the amount of the additive is more than necessary, resulting in poor dispersion in the binder resin.

As the binder resin used in the present invention, polystyrene, styrene / acrylic acid copolymer, styrene / methacrylic acid copolymer, which have been conventionally used in toners,
Styrene / acrylic acid ester copolymer, styrene / methacrylic acid ester copolymer, styrene / butadiene copolymer, saturated polyester resin, unsaturated polyester resin, epoxy resin, phenol resin, maleic acid resin,
Examples include coumarone resin, chlorinated paraffin, xylene resin, vinyl chloride copolymer, and a mixture thereof.

Further, the toner of the present invention may be mixed with an additive, if necessary. As the additive, for example, Teflon, a lubricant such as zinc stearate, or an abrasive such as cerium oxide, silicon carbide, strontium titanate, or a fluidity-imparting agent such as colloidal silica or aluminum oxide, or low molecular weight polyethylene, There are fixing aids such as low molecular weight polypropylene and various waxes.

When the toner of the present invention is used as a two-component developer, it is used as a mixture with carrier powder.
In this case, the mixing ratio of the toner and the carrier powder is preferably 0.5 to 10% by weight, particularly 2 to 4% by weight, as the toner concentration. As the carrier that can be used in the present invention, all known carriers can be used, for example, iron powder, ferrite powder,
Examples thereof include magnetic powder such as nickel powder, glass beads and the like, and those whose surface is treated with resin or the like.

The colorant used in the present invention includes
Any suitable pigment or dye is used. Toner colorants are well known, for example carbon black as a pigment,
Examples include aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, red iron oxide, phthalocyanine blue, and indanthrene blue. These are used in an amount necessary and sufficient for maintaining the optical density of the fixed image.
0.1 to 20 parts by weight, preferably 2 to 10 parts by weight
Good addition of parts by weight. Further, a dye is further used for the same purpose. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, methine dyes, etc., and the addition amount of 0.1 to 3 parts by weight is preferable with respect to 100 parts by weight of the binder resin.

To prepare the toner for developing an electrostatic image according to the present invention, a resin composition, a charge control agent, a pigment or dye as a colorant, an additive and the like are sufficiently mixed with a ball mill, a super mixer or other mixing machine. And then a heating roll,
Melt, knead and knead using a heat kneader such as a kneader or an extruder to disperse or dissolve a pigment or a dye in a resin in which the resins are mutually compatible, and after cooling and solidifying, crushing and classifying and averaging A toner having a particle size of 5 to 20 μm can be obtained.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
All parts in the following formulations are parts by weight.

Example 1 Aqueous solution of rhodamine dye 100 parts Extender pigment (BaSO ₄ , Al (OH) ₃ ) 150 parts After synthesizing the above formulation at room temperature, phosphorus, tungsten and molybdic acid were used as lakers. A 1.2 times mol amount is added to the dye, and a lake is formed at 90 ° C. The obtained precipitate is filtered, washed with water, dried, pulverized, and toned to obtain a desired lake pigment (charge control agent).

To 1 part of the obtained charge control agent, 100 parts of polyester resin, 10 parts of carbon black and 1 part of low molecular weight polypropylene were added, mixed well, melt-kneaded with a hot roll mill, cooled and coarsely crushed with a hammer mill. Then, pulverize with an air jet pulverizer. The obtained fine powder was classified to have a particle size of 5 to 15 μm, and 0.1 part of titanium oxide was mixed with 100 parts of the classified toner to obtain a toner. A developer was prepared by mixing 2.1 parts of this toner with 97.9 parts of spherical ferrite powder coated with a silicone resin and 0.002 part of titanium oxide as an additive.

Using this developer, 100,000 copies were repeatedly copied with a copying machine FT-4830 manufactured by Ricoh Co., Ltd., but the image was clear from the initial stage and the copy quality was not deteriorated. Also, the change in the charge amount of the developer was gentle. The charging rise of this toner was measured as follows. That is, the toner and the carrier were mixed so that the toner concentration was 2.1%, the mixture was stirred in a ball mill pot for a certain period of time, the toner was taken out, and the toner was blown by a blowing device to measure the charge amount. Table 1 shows the amount of charge at that time
Shown in.

Example 2 Rake formation was carried out in the same manner as in Example 1 except that the amount of the extender pigment in Example 1 was changed to 300 parts to obtain the desired charge control agent. Mixture of polyester resin and styrene / acrylic copolymer in 0.5 part of the obtained charge control agent 10
0 parts, 10 parts of carbon black and 1 part of low molecular weight polypropylene were added and mixed well, and then kneaded, pulverized, classified and mixed in the same manner as in Example 1 to obtain a toner having a particle size of 5 to 15 μm. 2.0 parts of this toner was mixed with 98 parts of spherical ferrite powder coated with a silicone resin and 0.002 part of hydrophobic silica to prepare a developer.

Using this developer, a copying machine F manufactured by Ricoh Co., Ltd.
Repeated copying of 100,000 sheets was carried out with T-4820, but the image was clear from the initial stage and no deterioration in copy quality was observed. Also, the change in the charge amount of the developer was gentle. Table 1 shows the charge rise.

Example 3 80 parts of polyester resin, 20 parts of styrene / acrylic copolymer, 8 parts of carbon black and 2 parts of low molecular weight polypropylene were added to 2 parts of the charge control agent obtained in Example 1 and mixed well, Kneading, pulverization, classification and mixing were carried out in the same manner as in Example 1 to obtain a toner having a particle size of 5 to 15 μm. 2.0 parts of this toner was mixed with 98 parts of spherical ferrite powder coated with a silicone resin and 0.002 part of titanium oxide to prepare a developer.

Using this developer, in the same manner as in Example 1,
Repeated copying was performed, but the image was clear from the beginning and no deterioration of the copying quality was observed.

Comparative Example 1 Rake formation was carried out in the same manner as in Example 1 except that the amount of the extender pigment of Example 1 was changed to 80 parts to obtain the desired charge control agent. 80 parts of the same polyester resin as in Example 2, 20 parts of styrene / acrylic copolymer, and 12 parts of carbon black were added to 1 part of the obtained charge control agent, and after mixing well,
Kneading, pulverizing, classifying and mixing in the same manner as in Example 1, 5 to 15
A toner having a particle size of μm was prepared.

When this toner was repeatedly copied in the same manner as in Example 1, a good image was obtained in the initial copying, but an unclear copied image was obtained after 50,000 sheets of continuous copying.

Comparative Example 2 A toner was prepared by kneading, pulverizing, classifying and mixing in the same manner as in Example 3 except that the amount of the charge control agent in Example 3 was changed to 0.03 part. When this toner was repeatedly copied in the same manner as in Example 1, a good image was obtained in the initial copying, but an unclear copied image was obtained after 30,000 continuous copying, and the charge amount of the developer also decreased. .

The results of the examples of the present invention are listed in Table 1 below.

[Table 1]

[0028]

The toner for developing an electrostatic image according to claim 1 uses a specific extender pigment in the process of manufacturing the charge control agent to be used, and the ratio of the dye to the extender pigment is within a certain range. By doing so, the water content of the obtained lake pigment can be controlled to make it stable, and since the charge control agent is compounded in the toner in a specific ratio, good charge stability and good durability can be obtained. It has excellent properties and can always obtain a stable image even after continuous use for a long period of time. In addition, since the charge rises quickly, it is possible to obtain a stable image without background stains from the initial stage.

In the electrostatic charge developing toner of claim 2, since a specific extender pigment is selected, a high-performance charge control agent can be easily obtained, and as a result, the charge stability is improved.

Claims (2)

[Claims] 1. An electrostatic charge image developing toner comprising at least a binder resin, a colorant and a charge control agent, wherein the charge control agent is obtained by synthesizing a rhodamine dye and an extender pigment. Ratio to extender pigment (weight ratio)
Of 0.1 to 1 in the range of 0.1 to 1, and the charge control agent is 0.1% to 100 parts by weight of the binder resin.
A toner for developing an electrostatic charge image, characterized by comprising from 5 to 10 parts by weight. 2. The extender pigment is aluminum hydroxide,
The toner for developing an electrostatic charge image according to claim 1, which is at least one selected from barium sulfate and calcium carbonate.