JPH10104873A - Electrophotographic toner and two-component electrophotographic developer containing same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrophotographic developer contg. a toner ensuring a stable quantity of electric charges independently of an environmental change over a long period of time, suppressing the charge-up of the toner especially in an environment at low temp. and humidity, preventing an image from lowering image density and increasing fogging by the suppressed charge-up and preventing defective cleaning and toner filming on a photoreceptor or an electrostatic recording body. SOLUTION: Colored resin particles contg. a colorant and a bonding resin are mixed with fine powder having a smaller average particle diameter than the colored resin particles to obtain the objective two-component electrophotographic toner. The fine powder is produced by a multistage soap-free polymn., alkyl acrylate and/or alkyl methacrylate esters are polymerized or copolymerized in a stage before the final stage and polymerizable carboxylic acid or its salt is polymerized in the final stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner and a two-component electrophotographic developer, and more particularly, to an electrophotographic developer which prevents deterioration in characteristics under a low-temperature and low-humidity environment.

[0002]

2. Description of the Related Art As a developing method applied to an electrophotographic method or an electrostatic recording method, a two-component type electrophotographic developer comprising a toner and a carrier (hereinafter, also referred to as a two-component type developer) is used. A method is known in which a toner is charged by frictional charging between a toner and a carrier, and an electrostatic latent image is visualized with the toner. The electrostatic latent image formed on the photoreceptor or the electrostatic recording medium is visualized by toner, and the toner image is transferred to transfer paper and then fixed to form a copy. On the other hand, the toner remaining on the photoreceptor or the electrostatic recording medium after the transfer without being transferred is cleaned to prepare for the next copying process. In general, a two-component developer in the case of a two-component developing method including a toner and a carrier is:
The toner is charged to the required charge amount and charge polarity by friction with the carrier, and the electrostatic latent image on the photoreceptor or the electrostatic recording material is developed using electrostatic attraction. It is important that the toner has good triboelectricity as determined by the following formula.

Various studies have been made to ensure good charging characteristics of the toner. For example, Japanese Patent Publication No. 52-32
Japanese Patent Application Laid-Open No. 256-64352 discloses a method in which chargeable fine particles are added to a toner as a charging auxiliary, a method in which fine resin powder having a polarity opposite to that of the toner is added to Japanese Patent Application Laid-Open No. 56-64352. Japanese Patent Application Laid-Open No. -160760 proposes a method of adding a fluorine-containing compound to a toner. However, in the case of the above-described method, it is not easy to uniformly disperse the additive on the toner surface, and it is difficult to avoid that the additives that cannot completely adhere to the toner particles form aggregates. This tendency is due to the fact that the triboelectric charging ability of the
Also, the finer the particle size, the more noticeable. In such a case, the amount of frictional charge of the toner becomes unstable, the image density is not constant, the image becomes fogged, or the content of the charging auxiliary agent changes when a large number of copies are made,
There are various problems such as that the image quality at the initial stage cannot be maintained.

[0004] Japanese Patent Publication No. 2-3173, 317
Nos. 4 and 3175 disclose a method in which fine particles of resin having an average particle size of 0.05 to 5 μm are mixed with a toner. However, these resin fine powders have high triboelectric charging ability, but have poor hydrophilicity on the surface, so that when a large number of copies are made under low temperature and low humidity, the charge amount of the toner obtained by mixing the resin fine powders increases. And there is a problem that the image density is reduced. Further, under low temperature and low humidity, the charge amount of the resin fine powder is too large, the resin fine powder is likely to aggregate, the mixing property is reduced,
Alternatively, the resin fine powder is likely to adhere to the carrier, which is one of the causes of poor friction between the carrier and the toner. As a result, the charging state becomes unstable, and fog (the toner flies and adheres to the non-image portion) Phenomenon) increases, and the quality of the copied image deteriorates.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and the charge amount of the toner is stable for a long period of time due to environmental changes. An object of the present invention is to provide an electrophotographic developer in which a reduction in image density and an increase in fog are prevented by suppressing the same, and poor cleaning of a photosensitive member or an electrostatic recording member or toner filming is prevented.

[0006]

According to a first aspect of the present invention, a colored resin particle containing a colorant and a binder resin and a fine powder having an average particle size smaller than the average particle size of the colored resin particle are provided. A two-component electrophotographic toner obtained by mixing, wherein the fine powder is a fine powder obtained by multi-stage polymerization by soap-free polymerization, and in the polymerization at a stage prior to the final stage, an alkyl acrylate and / or An electrophotographic toner, which is a fine powder obtained by polymerizing or copolymerizing an alkyl methacrylate and polymerizing a polymerizable carboxylic acid or a polymerizable carboxylate in the final stage of polymerization.

According to a second aspect of the present invention, the fine powder is a fine powder obtained by converting a carboxylic acid derived from a polymerizable carboxylic acid into a salt after polymerization in the final stage. Toner.

A third invention is the electrophotographic toner according to the first invention, wherein the polymerizable carboxylic acid salt is a divalent metal salt of a polymerizable carboxylic acid.

A fourth invention is characterized in that the fine powder is a fine powder comprising a carboxylic acid derived from a polymerizable carboxylic acid as a divalent metal salt after the final stage of polymerization. Is an electrophotographic toner.

The fifth invention is characterized in that the polymerization initiator used for the polymerization is a persulfate initiator or a redox initiator comprising a persulfate and a sulfoxy compound. 4. An electrophotographic toner according to any one of the fourth aspect to the fourth aspect.

A sixth aspect of the present invention is the electrophotographic toner according to any one of the first to fourth aspects, wherein the polymerization initiator used for the polymerization is a water-soluble azo-based initiator. is there.

In a seventh aspect, the fine powder has an average particle size of 0.0
The electrophotographic toner according to any one of the first to sixth inventions, wherein the toner has a thickness of 5 to 5 μm.

According to an eighth aspect of the present invention, there is provided the electronic device according to any one of the first to seventh aspects, wherein 0.01 to 10 parts by weight of a fine powder is mixed with 100 parts by weight of the colored resin particles. It is a photographic toner.

A ninth invention is a two-component electrophotographic developer containing the electrophotographic toner according to any one of the first to eighth inventions, and a carrier.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a fine powder used as an external additive is a fine powder obtained by multi-stage polymerization by soap-free polymerization, and in the final stage of polymerization, a polymerizable carboxylic acid or a polymerizable carboxylic acid is used. It is important that the fine powder is obtained by polymerizing an acid salt. That is, when the surface of the fine powder is coated with a layer containing a carboxylic acid or a carboxylate having relatively high hydrophilicity, the carboxylic acid or the carboxylate adsorbs moisture. To prevent excessive charge-up of
It is considered that the decrease in image density and the occurrence of fog under low temperature and low humidity can be suppressed and prevented.

The fine powder used in the present invention is a fine powder obtained by multi-stage polymerization by so-called soap-free polymerization. For example, in the case of two-stage polymerization, a dispersion containing the fine powder is obtained by the following method. Can be (1) A dispersion of fine particles of a polymer of acrylate and / or alkyl methacrylate or a dispersion of fine particles of a copolymer (hereinafter abbreviated as a first-stage dispersion) by the first-stage soap-free polymerization. Then, as a second-stage soap-free polymerization, a polymerizable carboxylic acid monomer is added to or dropped from the first-stage dispersion to effect soap-free polymerization. (2) In the method of (1), after the completion of the second-stage soap-free polymerization, a carboxyl group derived from a polymerizable carboxylic acid present near the surface of the dispersed particles is converted into a salt. (3) In the method of (1), in the second-stage soap-free polymerization, instead of the polymerizable carboxylic acid monomer, a salt of a polymerizable carboxylic acid is added or dropped to the first-stage dispersion, Performs soap-free polymerization. The above (1) to (3)
Is described in the case of two-stage polymerization, but also in the case of multi-stage polymerization of more than two stages, if the polymerizable carboxylic acid or polymerizable carboxylate is polymerized in the final stage of multi-stage polymerization The polymerization or copolymerization of the acrylic acid ester and / or the alkyl methacrylate may be any of the stages prior to the final stage, and is not limited to the stage immediately before the final stage.

In the present invention, the polymer or copolymer produced in the step before the final step includes a polymer of an alkyl acrylate monomer, a polymer of an alkyl methacrylate monomer, an alkyl acrylate monomer and A copolymer of an alkyl methacrylate monomer or a copolymer containing at least 50% by weight of an alkyl acrylate monomer or an alkyl methacrylate monomer and containing one or more other copolymerizable monomers is provided. No.

The alkyl acrylate monomer and alkyl methacrylate monomer used in the present invention include esterified products of acrylic acid or methacrylic acid with alcohols such as alkyl alcohols, alkoxy alcohols, aralkyl alcohols and alkenyl alcohols. Examples of the alcohol include methyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, alkyl alcohols such as hexadecyl alcohol; methoxyethyl alcohol, Alkoxy such as ethoxyethyl alcohol, methoxypropyl alcohol, ethoxypropyl alcohol Alcohol; benzyl alcohol, phenylethyl alcohol, such aralkyl alcohols phenylpropyl alcohol; allyl alcohol, include such alkenyl alcohols crotonyl alcohol, methyl acrylate, methyl methacrylate is preferable.

Other monomers which can be copolymerized with the above-mentioned alkyl acrylate monomer and alkyl methacrylate monomer include amides such as acrylonitrile, acrylamide, methacrylamide, N-dimethylacrylamide, N-dimethylmethacrylamide and nitriles. , Vinyl acetates, vinyl ethers; nitrogen-containing vinyl compounds such as vinyl carbazole, vinyl pyridine, and vinyl pyrrolide; aliphatic monoolefins such as ethylene, propylene, butene, and isobutylene; vinyl chloride, vinyl bromide, and 1,2-dichloroethylene 1,3-dibromoethylene, halogenated aliphatic olefins such as isopropenyl chloride, isopropenyl bromide, allyl chloride, allyl bromide, vinylidene chloride, vinyl fluoride and vinylidene fluoride; Ene, 1,3-pentadiene, 2
Conjugated diene-based aliphatic olefins such as -methyl-1,3-butadiene; and styrenes such as styrene and α-methylstyrene.

The fine powder used in the present invention may be obtained by polymerizing a polymerizable carboxylic acid in the final polymerization step as described above, or by polymerizing a polymerizable carboxylic acid salt in the final polymerization step. good. Fine powders having a carboxylic acid on the surface tend to be negatively charged, so it is preferable to add and blend them with colored resin particles that are positively charged, and fine powders having a carboxylate on the surface tend to be positively charged. Therefore, it is preferable to add and blend the colored resin particles with negative charge.

The polymerizable carboxylic acid used in the final polymerization step includes acrylic acid, methacrylic acid, α-
Ethyl acrylic acid, crotonic acid, α-methyl crotonic acid, α-ethyl crotonic acid, isocrotonic acid, tiglic acid, addition-polymerizable unsaturated aliphatic monocarboxylic acid such as ungeric acid, or maleic acid, fumaric acid, itaconic acid, Examples include addition-polymerizable unsaturated aliphatic dicarboxylic acids such as citraconic acid, mesaconic acid, glutaconic acid, and dihydromuconic acid. One or more of these can be used, and acrylic acid and methacrylic acid are preferred. As the polymerizable carboxylic acid salt used in the final polymerization step, various salts of the above-mentioned polymerizable carboxylic acid are used.

Salts used for forming carboxylic acid salts before or after polymerization include Na, Mg, K, Li, N
H ₄ , Ca, Ba, Zn, Fe, Cu, Al, Ni, C
hydroxides such as o and Cr, oxides, inorganic acid salts, organic acid salts and organic amines, among which Mg, Ca, Ba,
Hydroxides, oxides, inorganic acid salts, organic acid salts, and organic amines of divalent metals such as Zn, Fe, Ni, and Co are preferable, and hydroxides of Mg, Ca, Ba, and Zn are preferable. Substances, inorganic acid salts, organic acid salts and organic amines are preferred,
Most preferred are hydroxides, oxides, inorganic acid salts, organic acid salts and organic amines of Zn. Organic acids include formic acid, acetic acid,
And propionic acid. The amount of these salt-forming agents added is
It is preferable to add it so that it becomes equivalent to the carboxyl group of the used or used polymerizable carboxylic acid. Even if it is less than the equivalent, it is effective for improving the stability to the charging ability under low temperature and low humidity. Even if it is added in an equivalent amount or more, there is no problem because the excess portion can be removed by performing a water washing step later.

The amount of the polymerizable carboxylic acid or the polymerizable carboxylic acid salt used is preferably 0.05 to 20% by weight based on 100 parts by weight of the total amount of the monomers used up to the polymerization step before the final step. If it is less than 0.05 parts by weight, the effect of improving the image density under low temperature and low humidity is poor even when the produced fine powder is added to the colored resin to form a toner, and if it exceeds 20 parts by weight, the hydrophilicity of the surface of the fine powder becomes large. The triboelectrification ability tends to decrease because the effect of absorbing moisture becomes too large.

The polymerization initiator used in the soap-free polymerization of the fine powder used in the present invention includes a persulfate initiator, a redox initiator composed of a persulfate and a sulfoxy compound, and a water-soluble azo initiator. And the like. When polymerized using a persulfate-based initiator or a Redox-based initiator composed of a persulfate and a sulfoxy compound, the polymer tends to be negatively charged, and 2,2′-
Azobis (2-amidinopropane) hydrochloride, 2,2'-
Azobis (2-amidinopropane) acetate, 2,2'-
Azobis (N, N'-dimethyleneisobutylamidine)
When polymerized using a water-soluble azo initiator such as dihydrochloride, the polymer tends to be positively charged. In addition, a polymerization initiator may be appropriately selected.

The fine powder used in the present invention uses a water-soluble polymer compound as a protective colloid. Examples of the water-soluble polymer compound include polyvinyl alcohol, polyacrylamide, polyacrylic acid and salts thereof, and polyacrylic acid. Examples include methacrylic acid and its salts, polyethylene glycol, polyvinyl pyrrolidone, polyvinyl methyl ether, carboxymethyl cellulose and the like.

The fine powder to be used in the present invention is obtained by removing the water from the aqueous dispersion after the soap-free polymerization or after the soap-free polymerization, the surface carboxylic acid is converted into a salt using the above-mentioned salt forming agent. You just have to be your body. As a means for removing water, various drying methods and pulverization methods / pulverization methods usually used for powder production can be applied. After spray-drying the aqueous dispersion, the dried product is pulverized / pulverized. Is preferred.

The fine powder used in the present invention may be prepared by subjecting the surface carboxylic acid to a salt after the soap-free polymerization or after the soap-free polymerization by using the above salt-forming agent, and then subjecting the aqueous dispersion to a cross-flow filtration method. Emulsifier and the like can be removed from the mixture. For example, the aqueous dispersion is placed in a table-top emulsion filter (manufactured by Soken Chemical Co., Ltd.), and the aqueous dispersion is washed by flowing water to remove water-soluble polymer compounds and unreacted substances. After washing, water may be removed by the above method to obtain fine powder.

The fine powder used in the present invention can be obtained by various methods as described above.
The average particle diameter is preferably 5 μm, more preferably 0.1 to 2 μm. If the thickness is less than 0.05 μm, agglomeration is likely to occur under low temperature and low humidity, and the aggregates are liberated, and it is difficult to suppress or prevent a decrease in image density under low temperature and low humidity. On the other hand, if it exceeds 5 μm, the dispersion becomes non-uniform and it is difficult to integrate with the colored resin particles. Therefore, it is difficult to suppress and prevent the charge-up of the toner under low temperature and low humidity, and to suppress the decrease in image density under low temperature and low humidity.・ It tends to be difficult to prevent.
If the fine powder has a large number of sharp corners, the photoreceptor may be damaged. Therefore, the shape of the fine powder is preferably as small as possible with sharp edges and as round as possible, for example, spherical.

The toner for electrophotography (hereinafter abbreviated as toner) of the present invention is obtained by adding and mixing the above-mentioned fine powder with colored resin particles. The colored resin particles used in the present invention are those containing a binder resin and a colorant, and as the binder resin used, styrene, chlorostyrene,
Styrenes such as vinylstyrene, ethylene, propylene, butylene, monobutylene such as isobutylene, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl esters such as vinyl butyrate, methyl acrylate, ethyl acrylate, butyl acrylate, Dodecyl acrylate,
Octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate,
Alkyl acrylates such as dodecyl methacrylate and alkyl methacrylates, vinyl ethers such as vinyl ethyl ether and vinyl butyl ether,
Examples thereof include homopolymers or copolymers of vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropenyl ketone. Particularly typical binder resins include polystyrene and styrene-alkyl acrylate. Copolymers, styrene-alkyl methacrylate copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, styrene-maleic anhydride copolymers, polyethylene, polypropylene and the like can be mentioned. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide,
Modified rosin, paraffin and waxes can be mentioned.

Colorants for obtaining the colored resin particles used in the present invention include carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, quinoline yellow, methylene break chloride, phthalocyanine blue, and malachite green oxalate. Rate, lamp black, rose bengal and the like can be exemplified as typical ones. Further, a charge control agent may be blended with the colored resin particles. Examples include nigrosine dyes, quaternary ammonium salts, salicylic acid derivative metal complexes, and the like.

The colored resin particles used in the present invention are used after melt-kneading, cooling, pulverizing, classifying, etc., a binder resin, a colorant and the like according to a conventional method. The colored resin particles used preferably have an average particle size of less than about 30 μm, more preferably an average particle size of 3 to 20 μm. The toner of the present invention is preferably added with the fine powder in an amount of 0.01 to 10 parts by weight, more preferably 0.05 to 3.0 parts by weight, based on 100 parts by weight of the colored resin particles. .

As described above, the fine powder having a carboxylic acid or a salt thereof on its surface is less susceptible to environmental changes as described above, The toner of the present invention in which the fine powder is added to the colored resin particles has a good triboelectric charging ability against environmental changes because the adhesion between the particles is small and the mixing property with the colored resin particles is small. This makes it possible to have an excellent cleaning property. That is, since the carboxylic acid or its salt on the surface of the fine powder adsorbs moisture, the fine powder and the toner obtained by adding the fine powder can maintain stable chargeability without charging up even under low humidity. As described above, the fine particles have a smaller adhesion between the particles, and the fine particles can move freely on the surface of the colored resin particles. It is considered that a good cleaning property can be obtained because of the action of the lubricant particles at the interface between the body and the cleaning blade.

The toner of the present invention may be obtained by adding various additives to the colored resin particles in addition to the fine powder having a carboxylic acid or a salt thereof on the surface. For example, silica, titania, and alumina each having a fine particle surface subjected to a hydrophobic treatment, a conductive fine powder, or the like can be used in combination with the fine powder.

The developer of the present invention is a so-called two-component developer having a carrier and a toner (hereinafter abbreviated as a developer). The carrier that can be used in the developer of the present invention has an average particle diameter substantially equal to the toner particle diameter, or
Particles of up to 00 μm, iron, nickel, cobalt,
Various known materials such as iron oxide, ferrite, glass beads, granular silicon, and magnetic powder-dispersed resin particles are used. Further, the surface of these particles may be covered with a coating agent such as a fluorine resin, an acrylic resin, and a silicone resin.

The developer of the present invention is most preferably obtained by first mixing a fine powder and colored resin particles to obtain a toner, and then mixing the toner with a carrier. In advance, fine powder may be added and mixed.

The developer of the present invention can develop an electrostatic latent image formed on a photoreceptor or an electrostatic recording medium. That is, selenium, zinc oxide, cadmium sulfide, an inorganic photoconductive material such as amorphous silicon, phthalocyanine pigment, an electrophotographic electrostatic latent image formed on a photoreceptor made of an organic photoconductive material such as bisazo face, or An electrostatic latent image is formed on an electrostatic recording medium having a dielectric material such as polyethylene terephthalate using a needle electrode or the like, and the electrostatic latent image is formed on the electrostatic latent image by a developing method such as a magnetic brush method, a cascade method, or a touch-down method. A toner image is formed by the developer of the present invention. This toner image is transferred to a transfer material such as paper and then fixed to form a copy,
The toner remaining on the surface of the photoreceptor or the like is cleaned. Various methods such as a blade method, a brush method, a web method, and a roll method can be used as the cleaning method.

[0037]

【Example】

Production Example 1 100 parts of methyl methacrylate, 200 parts of distilled water, 0.3 part of potassium persulfate were placed in a 1 L four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a reflux condenser.
Add 0.2 parts of polyvinyl alcohol, and place
Soap-free polymerization was performed at 0 ° C. for 4 hours. Four hours later,
Acrylic acid (3 parts) was added, and the polymerization was further continued for 1 hour.
After completion of the polymerization, the reaction solution was cooled to 20 ° C., and 1.2 parts of calcium oxide was added to form a salt. The obtained emulsion was dried using a spray drier and pulverized with a jet mill to obtain a fine powder having an average particle diameter of 0.3 μm. When the fine powder thus obtained was observed with a scanning electron microscope (SEM), it was almost spherical. Table 1 shows the water content of the obtained fine powder under each environment.

[0038]

[Production Example 2] The emulsion obtained in the same manner as in Production Example 1 was filtered and washed using a desktop emulsion filter (manufactured by Soken Chemical Co., Ltd .: Crossflow filtration device), and sprayed in the same manner as in Production Example 1. It was dried using a drier and crushed with a jet mill to obtain a fine powder having an average particle diameter of 0.3 μm. The fine powder obtained in this manner is scanned with a scanning electron microscope (SE
When observed in M), it was almost spherical.

[0039]

Production Example 3 A fine powder having an average particle diameter of 0.2 μm was obtained in the same manner as in Production Example 2, except that calcium oxide was not used.

[0040]

Production Example 4 A fine powder having an average particle diameter of 0.4 μm was obtained in the same manner as in Production Example 2 except that 2 parts of zinc acetate was used instead of 1.2 parts of calcium oxide.

[0041]

[Production Example 5] Instead of 0.4 part of potassium persulfate,
2'-azobis (2-amidinopropane) hydrochloride 0.4
In the same manner as in Production Example 4, except that no zinc acetate was used, a fine powder having an average particle diameter of 0.4 μm was obtained.

[0042]

Production Example 6 A fine powder having an average particle size of 0.4 μm was obtained in the same manner as in Production Example 4, except that 2 parts of magnesium acetate was used instead of 2 parts of zinc acetate.

[0043]

Production Example 7 The procedure of Production Example 1 was repeated except that 5 parts of sodium methacrylate was used instead of 3 parts of acrylic acid, and no calcium oxide was used after emulsion polymerization.
A fine powder of 1 μm was obtained.

[0044]

Production Example 8 100 parts of methyl methacrylate, 200 parts of distilled water, 0.4 part of potassium persulfate were placed in a 1 L four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a reflux condenser.
Add 2 parts of polyoxyethylene nonylphenol and 0.5 parts of sodium lauryl sulfate, and add 8 parts in a nitrogen stream.
The reaction was performed at 0 ° C. for 4 hours. After the polymerization is completed,
After cooling to 0 ° C., the emulsion polymerized in the same manner as in Production Example 2 was filtered and washed with a crossflow filtration device, dried and pulverized to obtain fine particles having an average particle diameter of 0.1 μm. As in Production Example 2, the particles were substantially spherical.

[0045]

Production Example 9 60 parts of methyl methacrylate, 40 parts of acrylic acid, 200 parts of distilled water, 0.6 part of potassium persulfate were placed in a 1 L four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube and reflux condenser. , 4 parts of polyoxyethylene nonylphenol and 0.5 part of sodium lauryl sulfate, and reacted at 80 ° C. for 4 hours in a nitrogen stream. After completion of the polymerization, the reaction solution was cooled to 20 ° C., and fine particles having an average particle size of 0.1 μm were obtained in the same manner as in Production Example 8. As in Production Example 1, the particles were substantially spherical.

[0046]

Example 1 A copolymer of styrene and n-butyl methacrylate was used as a binder resin, and carbon black was used as a colorant. 100 parts of colored resin particles having an average particle size of 12 μm were obtained in Production Example 1. The fine powder (0.5 part) was mixed using a Henschel mixer to obtain a two-component electrophotographic toner of the present invention. Then, 3 parts of the above toner were mixed with 97 parts of a carrier obtained by coating a silicone-based resin on spherical ferrite powder having an average particle diameter of 100 μm to obtain a two-component type electrophotographic developer. Using this two-component electrophotographic developer, a continuous copy test of 50,000 sheets was performed with a commercially available copying machine. As shown in Table 2, the charge amount and image density under low temperature and low humidity were low even in the early stage of copying. Even after the continuous copy test of 50,000 sheets, there was almost no change. Further, although the reason is not well understood, fog hardly occurred under low temperature, low humidity and high temperature, high humidity.

[0047]

Examples 2 to 7 To 100 parts of the same colored resin particles as in Example 1, 0.5 part of the fine powder obtained in Production Examples 2 to 7 was mixed using a Henschel mixer, and the two components of the present invention were mixed. An electrophotographic toner and a two-component electrophotographic developer of the present invention were obtained and evaluated in the same manner as in Example 1. Table 2 shows the results. FIG. 1 shows the relationship between the image density and the number of copies under low temperature and low humidity in Example 4 and Comparative Example 1 described later.
Shown in

[0048]

Comparative Examples 1 and 2 To 100 parts of the same colored resin particles as in Example 1, 0.5 part of the fine powder obtained in Production Examples 8 and 9 was mixed using a Henschel mixer to obtain a two-component electrophotograph. And a two-component electrophotographic developer were obtained.
The same evaluation was made. Table 2 shows the results.

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

The effects obtained by the present invention are as follows. 1. Prevents decrease in image density at low temperature and low humidity.Even if a large number of copies are made in a low temperature and low humidity environment, the fine powder coated with the carboxylic acid or its salt added to the colored resin particles adsorbs moisture and becomes excessively large. As a result, a suitable charge amount can be maintained, and a decrease in image density can be prevented even when a large number of copies are made in a low-temperature and low-humidity environment. 2. An increase in fog at high temperature and high humidity can be prevented. 3. Cleaning failure can be prevented. When cleaning the toner remaining on the photoreceptor or the like, according to the developer to which the fine powder of the present invention is added, even if a large number of copies are made, cleaning failure does not occur. Generally, negatively charged ozone deposits that have fallen down by corona discharge on the photoreceptor accumulate and cause image defects. However, since the fine powder has a polar group on the surface, the ozone deposits and the like are removed. And has the effect of cleaning the surface of the photoreceptor.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a relationship between image density and the number of copies under low temperature and low humidity in Example 4 and Comparative Example 1.

[Procedure amendment]

[Submission date] November 18, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0037

[Correction method] Change

[Correction contents]

[0037]

【Example】

[Production Example 1] 100 parts of methyl methacrylate, 200 parts of distilled water, 0.3 parts of potassium persulfate were placed in a 1 L four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a reflux condenser.
And 0.2 part of polyvinyl alcohol, and soap-free polymerization was carried out at 80 ° C. for 4 hours in a nitrogen stream. After 4 hours, 3 parts of acrylic acid were added, and the polymerization was further continued for 1 hour. After completion of the polymerization, the reaction solution was cooled to 20 ° C., and 1.2 parts of calcium oxide was added to form a salt. The obtained emulsion is dried using a spray drier, crushed by a jet mill,
A fine powder having an average particle size of 0.3 μm was obtained. When the fine powder thus obtained was observed with a scanning electron microscope (SEM), it was almost spherical. Table 1 shows the water content of the obtained fine powder under each environment.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction contents]

[0038]

[Production Example 2] The emulsion obtained in the same manner as in Production Example 1 was filtered and washed using a desktop emulsion filter (manufactured by Soken Chemical Co., Ltd .: Crossflow filtration device), and sprayed in the same manner as in Production Example 1. It was dried using a drier and crushed with a jet mill to obtain a fine powder having an average particle diameter of 0.3 μm. The fine powder obtained in this manner is scanned with a scanning electron microscope (SE
When observed in M), it was almost spherical.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction contents]

[0043]

Production Example 7 The same procedure as in Production Example 1 was repeated except that 5 parts of sodium methacrylate was used instead of 3 parts of acrylic acid, and no calcium oxide was used after polymerization.
Was obtained.

Claims (9)

[Claims] 1. A two-component electrophotographic apparatus comprising a mixture of colored resin particles containing a colorant and a binder resin and fine powder having an average particle size smaller than the average particle size of the colored resin particles. A toner, wherein the fine powder is a fine powder obtained by multi-stage polymerization by soap-free polymerization, and in the polymerization at a stage prior to the final stage, alkyl acrylate and / or
Alternatively, the electrophotographic toner is a fine powder obtained by polymerizing or copolymerizing an alkyl methacrylate and polymerizing a polymerizable carboxylic acid or a polymerizable carboxylate in the final polymerization. 2. The electrophotographic toner according to claim 1, wherein the fine powder is a fine powder obtained by converting a carboxylic acid derived from a polymerizable carboxylic acid into a salt after polymerization in the final stage. 3. The electrophotographic toner according to claim 1, wherein the polymerizable carboxylic acid salt is a divalent metal salt of a polymerizable carboxylic acid. 4. The electrophotographic toner according to claim 2, wherein the fine powder is a fine powder obtained by converting a carboxylic acid derived from a polymerizable carboxylic acid into a divalent metal salt after polymerization in the final stage. . 5. The electron according to claim 1, wherein the polymerization initiator used in the polymerization is a persulfate-based initiator or a redox initiator composed of a persulfate and a sulfoxy compound. Photo toner. 6. The electrophotographic toner according to claim 1, wherein the polymerization initiator used in the polymerization is a water-soluble azo-based initiator. 7. The electrophotographic toner according to claim 1, wherein the fine powder has an average particle size of 0.05 to 5 μm. 8. The electrophotographic toner according to claim 1, wherein 0.01 to 10 parts by weight of a fine powder is mixed with 100 parts by weight of the colored resin particles. 9. A two-component developer for electrophotography, comprising the electrophotographic toner according to claim 1 and a carrier.