JPH0611882A - Electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE:To provide the toner which has excellent durability and with which always stable images are obtainable even after long-term use. CONSTITUTION:This electrostatic charge image developing toner contg. at least a coloring agent, resin and charge control agent is constituted by allowing conductive particulates to discontinuously exist in and on the charge control agent particulates. The conductive particulate are incorporated at 10 to 70 pts.wt. into the charge control agent and the charge control agent contg. the conductive particulates is incorporated at 0.1 to 10 pts.wt. into 100 pts.wt. resin. A means for mixing and adsorbing the particulates while adding the conductive particulates into the charge control agent particulates in the refining process for the production of the charge control agent particulates is adopted as a means for allowing the conductive particulates to discontinuously exist in and on the charge control agent particulates.

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 latent image such as electrophotography and electrostatic recording.

[0002]

2. Description of the Related Art In a toner for developing an electrostatic image, a binder resin used for the toner alone cannot obtain a certain charge property. Therefore, in order to control the toner to a desired triboelectric charge property, a dye, a pigment or the like is used. Addition of a charge controllable substance has been carried out. As a charge controllable substance which has been put into practical use in the field of the present invention, a nigrosine dye is used to give or control a positive charge to a toner, and a Japanese Patent Publication No. No. 26478, Japanese Patent Publication Sho 55
Examples of the metal-containing compounds disclosed in JP-A-42752 and the like. These compounds have particularly excellent properties among the conventionally proposed charge control substances in terms of the performance of imparting electric charge to toner particles, and also have a practically sufficient image quality in conventional copying machines. It was possible to provide a toner that gives

[0003]

However, as electrophotography and electrostatic recording media are becoming more personalized, faster, and more multifunctional, they have better durability stability, higher density, and no fog. There is a demand for a toner that provides an image with high resolution, high contrast, and excellent gradation reproducibility. Not only positive development and analog development, but also reversal development, digital development, low potential development, etc.
Various developing methods have been used, and a toner that gives high image quality to any developing method is required.

[0004] With miniaturization and personalization, it is always necessary to stably provide high-quality images under any environment. Further, it is necessary to stably provide a high-quality image by using a large amount of toner at one time due to the higher speed and by enduring continuous use for a long period of time. At the same time, there is a demand for a toner that accelerates the rise of charging during high-speed stirring with a carrier in a developing device and provides a stable high-quality image from the initial stage.

On the other hand, various materials have been used in order to improve not only the developability but also the fixability, anti-offset property, cleaning property and anti-blocking property required for toner. However, since the triboelectric charge amount greatly changes depending on the type of material, the charge control agent simply "provides" the charge, that is, the function of increasing the charge amount is not sufficient, and the charge amount of the toner remains constant. Control ”and must not interfere with the other required performance of the toner as indicated above,
Rather, the one that assists is preferable.

[0006] The toner is controlled so that it is always triboelectrically charged to a constant charge amount even under long-term use in any environment, and as a result, it is necessary to provide a stable high image quality. . Therefore, the conventional toner cannot satisfy the above-mentioned various requirements, and it is necessary to improve the charge control agent. An object of the present invention is to provide a toner having excellent durability and capable of always obtaining a stable image even after continuous use for a long period of time.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a charge control agent which gives rise to a stable high-quality image from the initial stage in which the frictional charge with the carrier rises quickly. . That is, the present invention is characterized in that in the toner for developing an electrostatic charge image containing at least a colorant, a resin and a charge control agent, conductive fine particles are discontinuously present in the charge control agent fine particles and on the surface thereof. The conductive fine particles are contained in an amount of 10 to 70 parts by weight, preferably 20 to 50 parts by weight, relative to the charge control agent, and the charge control agent containing conductive fine particles is included in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the resin. Is characterized by.

Further, as a means for discontinuously presenting conductive fine particles in and on the surface of the charge control agent fine particles, in the purification process of the production of the charge control agent fine particles, the conductive fine particles are mixed and adsorbed while being added. It is most appropriate to adopt means. Specifically, as a method of mixing and adsorbing the conductive fine particles with the charge control agent, after the charge control agent is synthesized by a known method, it is uniformly adsorbed by mixing and adsorbing the conductive fine particles while adding the conductive fine particles in the step of filtering and washing. You can let me do it.

Further, as the conductive fine particles, carbon black that effectively adsorbs the charge control agent in the manufacturing process is most suitable.

The effect of the charge control agent used in the present invention is that the resistance value of the charge control agent is maintained at a certain level by allowing the conductive control particles to exist discontinuously in and on the surface of the charge control agent particles. It is presumed that the charging stability, charging rise, etc. have improved.

Further, the presence of the conductive fine particles in the charge control agent fine particles and on the surface thereof discontinuously has the effect of the float electrode during development. When a resin layer is provided on the surface of the carrier to prevent the so-called spent formation, in which the resin of the ground toner adheres to the surface of the carrier, a conductive material is mixed in the resin layer to float the electrode during development. Although a method aiming at an effect has been proposed, in the case of the toner of the present invention, even if a carrier having an insulating surface is used, a conductive substance is applied to the resin layer due to a closer effect to the electrostatic latent image of the toner. In addition to the effect more than development by the mixed carrier, there is an advantage that the toner is not easily crushed even by high-speed stirring with the carrier in the developing device.

The binder resin used in the present invention includes polystyrene, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, and styrene-acrylic acid ester copolymer, which are conventionally used in toners. Coal, styrene-methacrylic acid ester copolymer, styrene resin such as styrene-butadiene copolymer, saturated polyester resin, unsaturated polyester resin, epoxy resin, phenol resin, maleic acid resin, coumarone resin, chlorinated paraffin, xylene resin, Examples thereof include vinyl chloride copolymers and mixtures of these resins.

Examples of the conductive fine particles used in the present invention include carbon black, tin oxide, lead oxide and antimony oxide. As the charge control agent used in the present invention, nigrosine dyes and azine dyes are used as the positive polarity ones, and Japanese Patent Publication Nos. 41-20153 and 44-6 as the negative polarity ones.
397, JP 57-141452, 58-111049, 61-101558,
Examples thereof include metal complex salts of monoazo dyes described in 63-66263 and the like, metal chelates of alkylsalicylic acid or salicylic acid, and the like.

Further, a colorant may be added to the toner of the present invention if necessary. As the colorant used in the toner of the present invention, any suitable pigment or dye is used.
Toner colorants are well known and include, for example, pigments such as carbon black, alinine black, acetylene black,
Naphthol yellow, Hansa yellow, Rhodamine lake, Alizarin lake, red iron oxide, phthalocyanine blue, indanthrene blue and so on. These are used in an amount necessary and sufficient for maintaining the optical density of the fixed image, and the amount added is 0.1 to 20 parts by weight, preferably 2 to 10 parts by weight, based on 100 parts by weight of the resin. Further, a dye is further used for the same purpose. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, methine dyes, etc.
The amount added is 0.1 to 20 parts by weight, preferably 0.3 to 3 parts by weight, based on 100 parts by weight.

In order to prepare the toner for developing an electrostatic image according to the present invention, a resin composition, a charge control agent in which conductive fine particles are mixed and adsorbed, and a pigment or dye as a colorant, an additive, etc. are added to a ball mill or the like. After thoroughly mixing with a mixer, use a heat kneader such as a heating roll, kneader, or extruder to melt, knead, and knead the meat to make the resins compatible with each other, and then disperse or dissolve the pigment or dye. After cooling and solidification, pulverization and classification can be performed to obtain a toner having an average particle size of 5 to 20 μm.

Further, the toner of the present invention may be mixed with an additive, if necessary. Examples of the additives include Teflon, lubricants such as zinc stearate or abrasive particles such as cerium oxide, silicon carbide and strontium titanate, or fluidity imparting particles such as colloidal silica and 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 0.5 to 10% by weight, preferably 3 to 5% 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, magnetic powder such as nickel powder, glass beads, etc., and their surfaces treated with a resin or the like. Something is included.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. All parts in the following formulations are parts by weight. Example 1 Styrene-acrylic acid copolymer (SBM-73 Sanyo Kasei) 100 parts Charge control agent (Cr-containing azo dye) mixed with 100 parts of conductive powder (carbon black) by 30 parts of control agent and adsorbed 3 Parts 12 parts of carbon black are melt-kneaded with a hot roll mill, cooled, coarsely pulverized with a hammer mill, and finely pulverized with an air jet type fine pulverizer. The obtained fine powder was classified to obtain a toner having a particle size of 5 to 15 μm. 3.5 parts by weight of this toner are mixed with 96.5 parts by weight of spherical ferrite powder coated with silicone resin,
Used as a developer. Using this developer, 100,000 copies were made with a PPC copier FT-7200 manufactured by Ricoh Co., Ltd., but the image was clear from the beginning and no deterioration in copy quality was observed.
Further, there was no change in the charge amount of the developer. Further, the charging rise of this toner was measured as follows. That is, the toner and the carrier are mixed so that the toner concentration becomes 3.5%, and after stirring for a certain period of time in a ball mill pot,
The agent was taken out and the toner was blown by a blower to measure the charge amount. Table 1 shows the charge amount at that time.

Example 2 100 parts of polyester resin (ATR-2010 manufactured by Kao Soap Co.) 100 parts of charge control agent (Cr azo dye containing Cr) mixed with 25 parts of conductive powder (tin oxide) 3.5 parts Carbon black 12 parts The above formulation was treated as in Example 1 to give a toner.
Ferrite carrier 96.5 for 3.5 parts of the obtained toner
The parts were mixed to prepare a developer. This developer was used to make 100,000 copies using a PPC copier FT-5740 manufactured by Ricoh Co., Ltd. A clear image was obtained from the beginning, and a stable and stable copy image was obtained. Table 1 shows the charge rising characteristics measured in the same manner as in Example 1.

Example 3 100 parts of styrene-methacrylic acid copolymer 100 parts of charge control agent (nigrosine dye) mixed with 30 parts of conductive powder (carbon black) 1 part carbon black 15 parts The toner was processed in the same manner as in Example 1. To 2 parts of the obtained toner, ferrite carrier
A developer was prepared by mixing 98 parts. Using this developer,
Ricoh's FT-4820 PPC copier was used to make 100,000 copies, but a clear image was obtained from the beginning, and a stable and stable copy image was obtained.

Comparative Example 1 A toner was prepared in the same manner as in Example 1 except that the conductive powder was removed. A developer was prepared by mixing 96.5 parts of a ferrite carrier with 3.5 parts of the obtained toner.
When this developer was used and evaluated in the same manner as in Example 1, a good image was obtained in the initial copying, but an unclear copy image was obtained after 50,000 sheets of continuous copying. The results of the examples of the present invention are listed below in the following table.

[0022]

[Table 1] Image density ………… Measured value with a Macbeth densitometer Blow-off Q / M …… The value obtained by blowing the toner in the developer and measuring the charge with a Keithlet electrometer. Ball mill Q / M …… The value obtained by mixing the toner and carrier to 3.5%, stirring for a certain time in a ball mill pot, and then blowing off the toner to measure the charge.

[0023]

As described above, in the present invention, the charge control agent is mixed and adsorbed with a predetermined amount of conductive fine particles in advance, so that the charge stability is improved, the durability is excellent, and even in continuous use for a long period of time. A stable image toner is always obtained. In addition, since the charge rises quickly, a stable image free of background stains can be obtained from the beginning.

Claims (3)

[Claims] 1. An electrostatic charge image developing toner containing at least a colorant, a resin and a charge control agent, wherein conductive fine particles are discontinuously present in the charge control agent fine particles and on the surface thereof. Toner for image development. 2. The toner for developing an electrostatic charge image according to claim 1, wherein the conductive fine particles are contained in an amount of 10 to 70 parts by weight with respect to 100 parts by weight of the charge control agent. 3. A charge control agent containing the conductive fine particles,
2. The toner for developing an electrostatic charge image according to claim 1, which is contained in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the resin.