JPH03100561A - Electrophotographic toner - Google Patents

Abstract

PURPOSE:To obtain a toner stable in conductivity at low cost by attaching a conductive polymer to the surface of each core particle. CONSTITUTION:The conductive polymer, such as an oxidation polymer of aniline, pyrrole, thiophene, derivatives thereof, is attached to the surface of each core particle for composing the toner by immersing the core particles into at least one kind of solvent, such as water or methanol, and stirring them in the presence of at least one kind of monomer, such as aniline or pyrrole, and an oxidant and a dopant, thus permitting an electrophotographic toner satisfying the requirement of stability to be obtained at low cost.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a toner for developing an electrostatic latent image in electrophotography, and more specifically, the present invention relates to a toner for developing an electrostatic latent image in electrophotography. This invention relates to a novel electrophotographic toner attached to a surface.

(Prior art) In electrophotography, a latent image is formed on a photoconductor made of a photoconductive substance, etc., and this is developed with a powder developer to make it visible. A common method is to fix on paper using a solvent. Developers for such electrophotography include: ■ One-component developer in which magnetic powder, colorant, conductivity imparting substance, charge control agent, fluidity improver, etc. are dispersed in a binder resin, and ■ Binder resin. It can be broadly classified into two-component developers consisting of a mixture of a toner in which a colorant, a conductivity-imparting substance, a charge control agent, a fluidity improver, etc. are dispersed, and a carrier of iron powder or ferrite powder. .

A two-component developer achieves development by causing a charged toner to adhere to an electrostatic latent image through friction with a carrier. On the other hand, magnetic toner, which is a one-component developer, differs depending on its resistance value; conductive toner is caused by induction of opposite polarity charges due to electrostatic charge on the photoreceptor, and high resistance toner is caused by polarization or charge injection within the same toner particle. Toner adheres to the photoreceptor. Furthermore, an insulating toner having a chargeability similar to a two-component developer is also used, and this toner is attached to a photoreceptor by applying an electric charge to the toner using a member for transporting the toner or friction between the toners. . Conductive particles are used as conductivity-imparting substances to control the conductivity of such toners or the insulation resistance that affects the amount of triboelectric charging.

(Problems to be Solved by the Invention) Carbon black, which also serves as a coloring agent, is used as the conductive particles, but since carbon black has high hygroscopicity, the amount added is particularly limited in two-component developers. If the amount is too large, the transferability in a high humidity atmosphere will deteriorate, and if it is too small, the amount of charge will become unstable, which will adversely affect the image quality. Furthermore, in one-component magnetic toners, there is a limit to the addition of conductive particles such as carbon black or graphite to areas where a large amount of magnetic material or colorant is contained in the toner. Furthermore, since conductivity is a surface phenomenon, a layer of carbon black or the like is often formed on the surface of the core substance that makes up the toner to form a conductive layer. In order to stabilize the properties, complicated steps must be taken, such as the need to fuse particles such as carbon black to the surface.

The present invention has been made with the object of providing a toner at a low cost that improves the problems of the conventional methods.

(Means for Solving the Problems) As a result of various studies to achieve the above object, the present inventors found that a toner in which a conductive polymer is attached to the surface of a core material is an excellent toner that can sufficiently meet the above object. The present invention was completed based on the new knowledge that the present invention has the following properties.

That is, the present invention is an electrophotographic toner characterized in that a conductive polymer, which is an oxidized polymer of aniline, virol, thiophene, and their derivatives, is attached to the surface of a core material constituting the toner.

The conductive polymer of the present invention is obtained by oxidative polymerization of aniline, pyrrole, thiophene, or their derivatives. It means a compound substituted with an alkyl group or an alkoxy group having numbers 1 to 18.

A method for attaching a conductive polymer to the surface of a core material is to immerse the core material in a solvent consisting of one or more of water, methanol, ethanol, propatool, and acetonitrile, and then immerse the core material in a solvent consisting of one or more of water, methanol, ethanol, propatool, and acetonitrile. -40 to 50 in the presence of one or more of those derivatives (hereinafter abbreviated as monomers), an oxidizing agent, and a dopant.
By stirring at a temperature of 1 minute to 10 hours, the oxidized polymer of the monomer is adhered to the surface of the core material, thereby producing an electrophotographic toner.

In the above method, solvents other than water, methanol, ethanol, propatool, and acetonitrile can also be used, but the proportion of the oxidized monomer precipitated in the treatment solution without being attached to the core material is limited. The use of the above-mentioned solvents is preferred in order to reduce and increase the utilization rate of the polymer.

Oxidizing agents used in oxidative polymerization include chlorine, bromine,
-10-gens such as argon; metal halides such as ferric chloride, boron trifluoride, arsenic pentafluoride, and antimony pentafluoride; peroxides such as hydrogen peroxide: persulfuric acid, persulfuric acid Persulfates and their salts such as potassium and ammonium persulfate; halogen acids and their salts such as iodic acid and potassium perchlorate; transition metal compounds such as potassium permanganate and chromic acid; protonic acids such as nitric acid and sulfuric acid, ozone, Examples include oxygen, and these may be used alone or in combination.

The dopant used in the present invention is a commonly used acceptor dopant. Specifically, 710 gen anions such as chlorine, bromine, iodine, and hydrogen chloride; halide anions such as hexafluoroline, hexafluoroline, and tetrafluoroborine; alkylbenzenesulfonic acid, benzenesulfonic acid anions; perchloric acid, perchlorine Examples include perchlorate anions such as acid norium; sulfate anions such as sulfuric acid; these may be used alone or in combination.

The amount of monomer, oxidizing agent, and dopant during polymerization will vary depending on the amount, shape, thickness, and desired resistance value of the toner being treated;
0.05 to 30 parts by weight per 100 parts by weight of the oxidizing agent, 0.05 to 30 parts by weight per 100 parts by weight of the solvent, and 0.01 to 20 parts by weight of the dopant per 100 parts by weight of the solvent.
When the amount of the core material is 0.1 to 50 parts by weight per 100 parts by weight of the solvent, the conductive polymer can be efficiently attached to the core material particles. The temperature when polymerizing monomers is
-40 to 50°C, more preferably -10 to 1
The temperature is about 0°C.

In the above method, iron (such as ferric chloride) is used as an oxidizing agent.
II) When a salt is used, the iron salt contained in the conductive polymer can be converted into a magnetic iron compound by a conventionally known method. For example, a method may be used in which a core material to which a conductive polymer is attached is placed in a solution containing a pH adjuster, and heat treatment and, if necessary, introduction of oxygen gas are used in combination.

The material constituting the core substance used in the present invention is a resin component mixed with magnetic powder, a coloring agent, a fluidity improver, a charge control agent, etc. as necessary.The resin component includes, for example, styrene resin, Styrene copolymer resins such as styrene-acrylic resin, styrene-butadiene copolymer resin, styrene-maleic acid copolymer resin, polyethylene, polypropylene, polyester, polyurethane, polyvinyl chloride, epoxy resin, polyvinyl butyral, rosin, modified rosin , paraffin wax, ketone resin, etc., and these may be used alone or in combination.

The conductive polymer is generally black in color and functions as a coloring agent itself, but there is no harm in mixing carbon black or other dyes or pigments into the core material as a coloring agent.

In producing the toner of the present invention, the core material constituent materials are thoroughly kneaded using a hot kneader such as a hot roll or a kneader, and then a core material is obtained by mechanical crushing and classification. There are several methods for attaching molecules, such as mixing a specified material with the monomers that constitute the binder resin, polymerizing this emulsified suspension to obtain a toner core material, and attaching a conductive polymer. It is desirable that the particle size of the dome is about 1 to 50 μm, preferably about 5 to 15 μm.

Further, the toner of the present invention can be mixed with a carrier and used as a two-component developer, but since it is normally used as a one-component developer, the core material is prepared by adding a magnetic material. is desirable. The magnetic material contained in the binder resin constituting the core material includes iron, cobalt,
Ferromagnetic elements such as nickel and alloys and compounds containing these such as magnetite, hematite, and ferrite can be used as appropriate, and their particle size is 0.1 to 0.8 μm1.
More preferably, it is 0.3 to 0.5 μm, and the binder resin 1
The content is preferably 10 to 120 parts by weight, more preferably 30 to 100 parts by weight.

(Examples) Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples in any way. Note that parts in the examples represent parts by weight.

Example 1 61 parts of styrene-butyl acrylate copolymer, 36 parts of magnetite, and 3 parts of low molecular weight polyethylene wax are mixed. This mixture is heat-melted and kneaded using a roll mill, cooled, coarsely ground using a hammer mill, and further finely ground using a jet mill.

Next, it was classified using an air classifier to obtain a core material with a particle size of 8 to 15 μm.

61.3 parts of water and 8.13 ffl of iron(III) chloride hexahydrate
Add 4.88 parts of this core substance to a solution consisting of 4 parts of methanol.
．． It was wetted and added at 88 parts. While stirring this mixed solution at 0° C., a solution prepared by dissolving 0.81 parts of pyrrole in 20 parts of water was added, stirred for 3 minutes, and filtered.

After washing with water and then methanol, it was dried to obtain a black conductive magnetic toner. This toner exhibited a resistance value of 3×10 2 Ω·cm. When the electrostatic latent image formed on the zinc oxide photoreceptor was visualized using this magnetic toner and the image was transferred onto recording paper, a clear image without fogging was obtained.

Example 2 58 parts of styrene/methyl methacrylate copolymer, 36 parts of magnetite, 2.5 parts of low molecular weight polyethylene wax
1 part and 3 parts of carbon black were mixed. This mixture was treated in the same steps as in Example 1 to obtain a core material with an average particle size of 12 μm.

4 parts of this core material were moistened with 4 parts of acetonitrile and added to an aqueous solution consisting of 69 parts of water, 1.3 parts of concentrated hydrochloric acid and 0.6 parts of aniline. The mixture was cooled to 0° C. without stirring, containing 17.9 parts of IN-sulfuric acid and 3.0 parts of ammonium persulfate.
Two parts were added and stirred for 20 minutes. After filtration,
It was washed with water and methanol and dried to obtain a black magnetic toner.

This toner exhibited a resistance value of 4×10 5 Ω·Cm. When this magnetic toner was used to visualize the electrostatic latent image formed on the zinc oxide photoreceptor and the image was transferred onto recording paper, a clear image without any looseness was obtained.

Example 3 30 parts of water, 31.3 parts of acetonitrile and iron chloride (III
) 4.88 parts of the core material obtained in Example 2 were moistened with 4.88 parts of acetonitrile and added to a solution consisting of 8.13 parts of hexahydrate. While stirring this mixture at room temperature, a solution prepared by dissolving 0.81 parts of 3-methoxythiophene in 20 parts of acetonitrile was added, stirred for 30 minutes, and filtered. After washing with water and then with methanol, it was dried to obtain a black magnetic toner. This toner exhibited a resistance value of 6×10 9 Ωφcm. When the electrostatic latent image formed on the zinc oxide photoreceptor was visualized using this magnetic toner and transferred onto recording paper, a clear image without fogging was obtained.

Example 4 70 parts of styrene-butyl acrylate copolymer, 24 parts of magnetite, 2.5 parts of low molecular weight polyethylene wax, and 3 parts of carbon black were mixed.

This mixture was treated in the same manner as in Example 1, with particle sizes of 8 to 8.
A core material of 15 μm was obtained. This core material was treated in the same manner as in Example 1 to adhere polypyrrole to the surface of the core material to obtain a black magnetic toner. This toner is 8X102Ω・cm
showed a resistance value of This toner was placed in an aqueous sodium hydroxide solution, the pH was adjusted to about 11, and the toner was heated at 90° C. for 60 minutes, so that the iron salt contained in the polypyrrole became a magnetic oxide. The core material to which polypyrrole containing the magnetic oxide was attached was filtered off, washed with water, and dried to obtain a magnetic toner. This toner exhibited a resistance value of 8×10 3 Ω·cm. When the electrostatic latent image formed on the zinc oxide photoreceptor was visualized using this magnetic toner and transferred onto recording paper, a clear image without any looseness was obtained.

(Effects of the Invention) In the present invention, a simple device is used to stir the core substance in a solution on the surface of a core material made of fine particles of polymer resin or rubber into which a colorant, magnetic powder, charge control agent, etc. are mixed as necessary. A conductive polymer can be attached by a simple method. This adhesion is strong because a portion of the conductive polymer is composited with the core material and generally forms an extremely thin layer covering the core material.

The electrophotographic toner of the present invention has a resistance of 1Ω・cm to 1015Ω・
The resistance can be freely controlled to a level of about cm, and since the conductive mechanism of the conductive polymer is electron conduction, it is stable and is not affected by the surrounding environment, especially humidity.

Furthermore, since conductive polymers are generally black, they also have the function of a coloring agent, and if an iron (III) salt is used as an oxidizing agent during oxidative polymerization of monomers, conductive polymers can be formed by a known method. Magnetism can also be imparted.

Therefore, the present invention makes it possible to provide at a low cost an electrophotographic toner that satisfies the toner characteristics that require higher functionality and stability.

Claims (1)

[Claims] 1. A toner for electrophotography, characterized in that a conductive polymer is attached to the surface of a core substance constituting the toner. 2. The electrophotographic toner according to claim 1, wherein the conductive polymer comprises a polymer of aniline, pyrrole, thiophene, or a derivative thereof.