JPH0546942B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a toner used to develop an electrical latent image in electrophotography or electrostatic printing, and more particularly to a method for producing a capsule toner suitable for pressure fixing. Conventionally, as an electrophotographic method, U.S. Patent No. 2297691
specification, Japanese Patent Publication No. 42-23910 (U.S. Patent No.
A number of methods are known, as described in Japanese Patent Publication No. 3666363) and Japanese Patent Publication No. 43-24748 (U.S. Pat. No. 4071361), but generally they utilize a photoconductive substance, An electrical latent image is formed on the photoreceptor by various means, then the latent image is developed using toner, and if necessary, the toner image is transferred to a transfer material such as paper, followed by heating, pressure, etc. Alternatively, the object is obtained by fixing with solvent vapor or the like. Various developing methods are also known for visualizing electrical latent images using toner, and these can be broadly classified into dry developing methods and wet developing methods. The former method is further divided into a method using a two-component developer and a method using a single-component developer. Among the two-component developing methods, the magnetic brush method using an iron powder carrier, the cascade method using a bead carrier, etc. are widely put into practical use, depending on the type of carrier for conveying the toner. All of these methods are excellent methods that can produce good images relatively stably, but on the other hand, they have common drawbacks associated with two-component developers, such as carrier deterioration and image fluctuations due to fluctuations in the toner and carrier mixing ratio. has. In order to avoid these drawbacks, various development methods using a one-component developer consisting only of toner have been proposed, and among these, many excellent methods using magnetic toner have been put into practical use. A developing method that uses a magnetic one-component developer is the MagneDry method that uses conductive toner, but although this is stable for development, it has poor transferability on transfer materials such as plain paper. There's a problem. Therefore, methods using high-resistance magnetic toner with good transferability include a method using dielectric polarization of toner particles and a method of transferring charge by disturbing the toner, but these methods have problems with the stability of development. In addition, as a developing method proposed by the present applicant in recent years,
42141 and Japanese Patent Laid-Open No. 55-18656, methods of developing a latent image by flying toner particles have been put into practical use. This involves coating a very thin layer of magnetic toner on a sleeve, which serves as a toner carrier and charge-imparting material, triboelectrically charging it, and then bringing it very close to and in contact with an electrostatic image under the action of a magnetic field. The images are developed by facing each other without any problem. According to this method, by applying an extremely thin layer of magnetic toner onto the sleeve, the chances of contact between the sleeve and the toner are increased, and sufficient frictional electrification is possible, and the toner is supported by magnetic force.
In addition, by moving the magnet and toner relatively, the toner particles are disaggregated and sufficiently rubbed against the sleeve, and the toner is supported by magnetic force and does not come into contact with the electrostatic image. By developing the images facing each other, excellent images can be obtained due to factors such as prevention of background fog. In order to fix the toner image developed in this way, a heat fixing method is generally used in which the toner image is heated and melted using an infrared heater or a heated roller, and then fused and solidified to the support, but this method is used to prevent the risk of fire. , For reasons such as reducing power consumption, there is a shift toward a pressure fixing method using a rigid roller, which eliminates or essentially reduces the need for heating. especially,
This pressure fixing method has advantages such as there is no risk of burning the copy sheet, the copying can be done without waiting time once the copying machine is turned on, high-speed fixing is possible, and the fixing device is simple. many. However, conventional toner cannot be used as is in such a pressure fixing method.
This is because toner materials are selected to suit each fixing method, and toners used for a particular fixing method cannot generally be used for other fixing methods. For example, it is impossible to use a toner for heat-melting fixing using an infrared heater as a toner for fixing with a heat roller, and furthermore, there is almost no compatibility between toner for heat fixing and toner for pressure fixing. Therefore, toners suitable for each fixing method are being researched and developed, and even for single-component toners that have excellent development properties as mentioned above, it is possible to maintain the advantages and develop toner properties suitable for pressure fixing. Various proposals have been made to provide this. In particular, in such a toner that can be fixed by pressure, the constituent resin must have characteristics suitable for pressure fixing, and resins suitable for this purpose are actively being developed. However, it has excellent pressure fixing properties, does not cause any offset phenomenon to the pressure roller, and has stable developing and fixing performance even after repeated use, and does not adhere to the carrier, metal sleeve, or photoreceptor surface. A practical pressure fixing toner with good storage stability that does not cause agglomeration or caking during storage has not yet been obtained. In particular, problems remain in the fixability to plain paper in terms of pressure fixability. Various capsule-type toners provided with a hard resin shell have been proposed in order to satisfy the various characteristics required of such pressure-fixing toners by forming multiple layers of toner particles. Such proposals include, for example, capsule toners with a soft material core as seen in Japanese Patent Publication No. 54-8104 (US Patent No. 3,788,994), or capsule toners with a soft resin solution core. However, there are many unresolved problems such as insufficient pressure fixing ability and offset phenomenon, and it has not been put into practical use. Furthermore, in the capsule toner described above, the strength of the shell material is not sufficient, so the durability as a developing material is poor, and the surface of the developing sleeve, photoreceptor, carrier, etc. may be contaminated or fused due to peeling of the shell material. Easy to occur. Furthermore, if the thickness of the shell is increased to a level that satisfies the strength of the shell material, toner fixability will be significantly reduced. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a capsule toner free from the above-mentioned drawbacks by improving the shell material. In particular, it is an object of the present invention to
This is a highly durable capsule toner that exhibits better fixing properties at lower pressures than before, and does not cause contamination or adhesion to the surfaces of the developing sleeve, photoreceptor, carrier, etc. even when making multiple copies. The purpose is to provide a manufacturing method. Furthermore, another object of the present invention is to provide a method for producing a capsule toner that exhibits excellent charge controllability and stable charge controllability. Furthermore, another object of the present invention is to provide electrostatically transferable capsules that contain magnetic fine particles and exhibit good pressure fixing properties and developability even when used as a toner for a one-component developer. A method for producing toner is provided. Specifically, the present invention provides a method for producing a capsule toner comprising a core material containing polyethylene and/or paraffin wax, and an outer shell that covers at least a portion of the core material. After dispersing the core material in a monomer system obtained by uniformly dissolving or dispersing a crosslinking agent, a crosslinking agent, and a polymerization initiator, or uniformly wetting the surface of the core material with the monomer system, The present invention relates to a method for producing a capsule toner, which comprises dispersing and polymerizing the core material, and covering at least a portion of the core material with an outer shell containing a crosslinked polymer of a vinyl monomer. That is, according to the research of the present inventors, in order to achieve the above-mentioned object, the outer shell constituting the capsule toner must be formed by a specific polymerization method including polymerization on a core material of the above-mentioned specific monomer system. It has thus been discovered that it is extremely effective to contain a crosslinked polymer of vinyl monomers synthesized. The present invention will be explained in more detail below. In the following descriptions, "%" and "parts" represent quantitative ratios.
are based on weight unless otherwise specified. The core material of the capsule toner of the present invention is basically formed by dispersing a colorant and, if necessary, magnetic powder into fine particles in a resin as a pressure fixing component. Polyethylene and paraffin wax are used as the resin constituting the core material. Particularly preferred polyethylene is one having a melt viscosity of 600 CPS or less at 140°C. So-called low molecular weight polyethylene, also known as polyethylene wax, is produced by a polymerization method or a decomposition method. Examples of commercially available products include the following. AC Polyethylene #9 (Allied Chemical) (0.94g/cm ³ , 350CPS) Hiwatux 310P (Mitsui Petrochemical) (0.94g/cm ³ , 250CPS) Hiwatux 410P (Mitsui Petrochemical) (0.94g/cm ³ , 550CPS) Hiwatux 405P (Mitsui Petrochemical) (0.96g/cm ³ , 550CPS) Hiwatux 400P (Mitsui Petrochemical) (0.97g/cm ³ , 550CPS) Hiwatux 200P (Mitsui Petrochemical) (0.97g/cm ³ , 70CPS) Hoechst Wax PE130 (manufactured by Hoechst AG) (0.97g/cm ³ , 117CPS) There are also paraffin waxes as shown in the following table.

【table】

【table】

[Table] In the present invention, it is preferable to use the above-mentioned polyethylene and paraffin wax in an appropriate combination. Of course, if necessary, the polyethylene,
Several types of parafine waxes may be combined. The blending ratio of polyethylene and paraffin wax is 8/2 to 0/10 by weight.
In particular, a range of 6/4 to 1/9 is preferably used. As the coloring agent contained in the core material of the capsule toner of the present invention, known dyes and pigments can be used. Examples include various types of carbon black, aniline black, naphthol yellow molybdenum orange, rhodamine lake, alizarin lake, methyl violet lake, phthalocyanine blue, nigrosine methylene blue, rose bengal, and quinoline yellow. When the capsule toner of the present invention is used as a magnetic toner, magnetic powder can be contained in the core material. Magnetic powders include iron, cobalt,
Powders of ferromagnetic elements such as nickel or manganese, and alloys and compounds containing these such as magnetite and ferrite are used. This magnetic powder may also be used as a coloring agent. The content of this magnetic powder is based on 100 parts of all the resin in the core material.
A range of 15 to 70 copies is good. The core material of the capsule toner of the present invention can be obtained by melt-kneading the above-mentioned components, pulverizing them, and further classifying them as necessary to obtain an average particle size of 5 to 15 μm.
It is prepared as microparticles. The capsule toner of the present invention is produced by covering the above-mentioned core material with an outer shell mainly composed of a crosslinked polymer of vinyl monomers by a specific polymerization method in an aqueous dispersion medium as described below. It is obtained by As vinyl monomers, those shown below may be used alone or in combination of two or more. Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-mexistyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4- Dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n
- Styrenic monomers consisting of styrene and its derivatives such as hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene; ethylene, propylene, butylene, Ethylenically unsaturated monoolefins such as isobutylene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate, and vinyl benzoate; methyl methacrylate, α-Methylene aliphatic such as ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, etc. Monocarboxylic acid esters; α-methyl chloromethacrylate, maleic acid, maleic esters; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, acrylic acid Dodecyl, 2-ethylhexyl acrylate, stearyl acrylate, acrylic acid 2
- Acrylic esters such as chloroethyl and phenyl acrylate; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone; N-vinylpyrrole ,
N-vinyl compounds such as N-vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone; vinylnaphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylnitrile, and acrylamide; dimethylaminoethyl methacrylate, dimethylphenyl acrylate, Vinyl monomers containing tertiary amino groups such as dimethylaminopropylacrylamide and diethylaminoethyl methacrylate. Further, as the crosslinking agent, for example, the following can be used. Namely, divinylbenzene, divinylnaphthalene, divinyl ether, divinyl sulfone, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol. Dimethacrylate, 1,6-hexane glycol dimethacrylate, nefopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate,
polypropylene glycol dimethacrylate,
2,2'bis(4-methacryloxydiethoxyphenyl)propyne, 2,2'bis(4-acryloxydiethoxyphenyl)propyne, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetra Acrylate, dibromneopentyl glycol dimethacrylate, diallyl phthalate,
Common crosslinking agents such as 2,6-diacrylphenol and diallylcarbinol can be used as appropriate. If these crosslinking agents are used in an excessive amount, the fixing properties will be poor. In addition, if the amount used is too small, properties such as blocking resistance and durability necessary for toner will deteriorate, and during heat and pressure fixing, some of the toner will not completely adhere to the paper and will stick to the surface of the heating roller, causing the next It becomes difficult to prevent the offset phenomenon of transfer to paper. Therefore, these crosslinking agents are preferably used in an amount of 0.01 to 15%, particularly 0.02 to 13%, based on the total amount of vinyl monomer and crosslinking agent. The polymerization initiator is generally a substance that generates radicals when decomposed by heat or light, and is preferably oil-soluble. Specifically, examples of azobisnitrile include 2,2'-azobisisobutyronitrile, 2,2'-azobispropionitrile, 2,2'-azobisvaleronitrile,
2,2'-azobis(2,4-dimervaleronitrile), etc.; as organic peroxides, benzoyl peroxide, nuclear-substituted benzoyl peroxide, lauroyl peroxide, acetyl peroxide, cumene hydroperoxide, etc.; As azo and diazo compound systems,
Diazoaminobenzene, azothioether, etc.;
Examples of sulfins include aromatic sulfinic acids. Oil-soluble redox polymerization initiators are also used, and oxidizing agents such as hydroperoxides, dialkyl peroxides, and diacyl peroxides and tertiary amines, naphthenates, mercaptans, and organometallic compounds [Al
(C ₂ H ₅ ) ₃ , B(C ₂ H ₅ ) ₃ , Zn(C ₂ H ₅ ) _{2 ,} etc.]. These initiators are generally sufficient in an amount of about 0.1 to 10% (more preferably 0.5 to 5%) of the total amount of vinyl monomer and crosslinking agent. In order to avoid agglomeration or coalescence of particles during polymerization in an aqueous suspension system described below when forming an outer shell covering at least a portion of the core material of the present invention,
It is preferable to use a suitable dispersant, for example polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose,
Ethyl cellulose, sodium salt of carboxymethyl cellulose, polyacrylic acid and their salts, starch, gum alginate, zein, casein, tricalcium phosphate, talc, barium sulfate, bentonite, aluminum hydroxide, ferric hydroxide, Titanium hydroxide, sodium hydroxide, etc. can be included in the aqueous phase and used. These dispersants are used in a stabilizing amount in the continuous phase, preferably in the range of about 0.1 to 10% by weight based on the aqueous dispersion medium. Further, for fine dispersion of the inorganic dispersant, a surfactant may be used in an amount of 0.1% by weight or less based on the aqueous dispersion medium. This is to promote the intended action of the above-mentioned dispersion stabilizer, and specific examples include sodium dodecylbenzenesulfonate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, allyl-alkyl- Sodium polyether sulfonate, sodium oleate,
Sodium laurate, sodium caprate,
Sodium caprylate, sodium caproate,
Potassium stearate, calcium oleate,
Sodium 3,3-disulfone diphenyl urea-4,4-diazo-bis-amino-8-naphthol-6-sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl- Sodium triphenylmethane-4,4-diazo-bis-β-naphthol-disulfonate and others can be mentioned. In addition to the above-mentioned crosslinked polymer, the outer shell of the capsule toner of the present invention may contain up to 75% of other resins. Examples of such other resins include styrene and substituted products thereof such as styrene, P-chlorostyrene, and P-dimethylamino-styrene; methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, and methacrylic acid. Acrylic acid or methacrylic acid esters such as ethyl, butyl methacrylate, methacrylic acid N,N-dimethylaminoethyl ester; maleic anhydride or half esters, half amides or diesterimides of maleic anhydride;
Nitrogen-containing vinyls such as vinylpyridine and N-vinylimidazole; Vinyl acetals such as vinyl formal and vinyl butyral; Vinyl monomers such as vinyl chloride, acrylonitrile, and vinyl acetate; Vinylidene monomers such as vinylidene chloride and vinylidene fluoride; ethylene, propylene, etc. In addition to monomers or copolymers of monomers such as olefins, polyesters, polycarbonates, polysulfonates, polyamides, polyurethanes, polyureas, epoxy resins, rosins, modified rosins, terpene resins, phenolic resins, aliphatic or alicyclic resins are used. Resins such as hydrocarbon resins, aromatic petroleum resins, melamine resins, polyether resins such as polyphenylene oxide, or thioether resins can be used alone or in combination. In order to incorporate these other resins into the outer shell of the capsule, these resins may be dissolved or dispersed in the monomer mixture that provides the crosslinked polymer and then polymerized to form the outer shell. . The polymerization method for obtaining the capsule toner of the present invention may be carried out as follows. That is, the core material is dispersed in a monomer system obtained by uniformly dissolving or dispersing the vinyl monomer, a polymerization initiator, and other resins added as necessary, or the surface of the core material is coated with the monomers. After uniformly wetting with a system, polymerization may be carried out by dispersing in an aqueous phase containing a dispersant as necessary using a conventional stirrer, homomixer, homogenizer, etc. The polymerization temperature is
The range is 30 to 100°C when a normal initiator is used, and -10 to +50°C when a redox initiator is used. After the reaction, the generated capsule toner particles are washed, filtered, decanted, and
By performing a suitable method such as centrifugation, collecting and drying, a capsule toner having an outer shell thickness of 0.05 to 0.5 microns and an average particle size of 5 to 18 microns is generally obtained. As described above, according to the method for producing a capsule toner of the present invention, the core substance is dispersed in a monomer system obtained by uniformly dissolving or dispersing a vinyl monomer, a crosslinking agent, and a polymerization initiator. Alternatively, after uniformly wetting the surface of the core material with the monomer system, it is dispersed in an aqueous phase and polymerized to transform at least a portion of the core material into an outer shell containing a crosslinked polymer of vinyl monomers. The capsule toner obtained has (i) excellent durability as a developer and has excellent properties such as not causing fusion to the carrier, developing sleeve, or photoreceptor surface, and (ii) ) It also has good charge control properties, provides clear and fog-free images, has stable development performance even after multiple copies are made, has a long service life, and (iii) does not aggregate or form cakes during storage. (iv) Furthermore, even when containing magnetic fine particles to make a magnetic toner for one-component developer, it has excellent developability and fixing performance, and is electrostatically transferable. becomes possible. Hereinafter, the present invention will be specifically explained with reference to Examples. Example 1 AC polyethylene #9 (manufactured by Allied, Chemical)
20 parts paraffin wax (made in Japan wax) 80 parts magnetite 60 parts The above ingredients were melted and mixed at 150℃, granulated with a spray dryer, and then dry classified to obtain a particle size of 9.1±4.5μ and a sphere. A core substance of the shape is obtained,
This was cooled to -20°C. Meanwhile, 40 g of styrene, 10 g of n-butyl acrylate, 3 g of dimethylaminoethyl methacrylate-styrene copolymer (molar ratio 1:9), 1.0 g of benzoyl peroxide, 0.6 g of dimethylaniline, 3 g of polyethylene glycol #200 dimethacrylate (Shin Nakamura Chemical), and TK homopolymer. Like a mixer (manufactured by Tokushu Kika Kogyo),
The monomer mixture solution obtained by uniformly mixing for about 5 minutes at -20°C in a container equipped with a high shear mixing device and 100 g of the cooled core material obtained above were mixed at -20°C.
The mixture was mixed at ℃ to obtain a slurry. On the other hand, 2g of polyvinyl alcohol is added to 1
The mixture was dispersed in water using the homomixer described above and kept at 5°C. The above slurry was added to this system under stirring using a TK homomixer, and the slurry was heated at approximately 4000 rpm and 30°C.
The mixture was stirred for about 40 minutes. Thereafter, this reaction mixture system was stirred with a paddle stirring blade to complete polymerization, and then washed with water and dried to obtain encapsulated particles. Next, 0.36 g of hydrophobic colloidal silica (manufactured by Nippon Silica Kogyo) was externally added and mixed to 90 g of the capsule particles to obtain a developer. For 1g of this developer, 9g of iron powder (200-300 mesh)
The amount of triboelectric charge was measured using a known measuring method and found to be +17.0 μc/g. After applying this developer to a developing machine having a magnetic sleeve and developing a latent image having a negative electrostatic charge,
Transferred onto high quality paper. When the transfer paper with the toner image was passed through a pressure fixing machine consisting of two pressure rollers that can apply pressure from both ends, it was almost completely fixed at a speed of 125 mm/sec and a linear pressure of 10 kg/cm. showed his sexuality. The image density was 1.3, and a clear and good reverse image without fog was formed. Furthermore, at a speed of 125 mm/sec in the developing machine, 8
After the durability test of idle rotation for several hours, the image was printed again, and the image density was 1.5, showing little change in image quality and excellent durability. The amount of triboelectric charge of the developer at this time was +18.3 μc/g, there was no contamination or fusion on the sleeve surface, and when the toner surface was observed with an electron microscope, no peeling of the wall occurred. Comparative Example 1 A developer was obtained by encapsulating and externally adding colloidal silica in the same manner as in Example 1, except that 3 g of polyethylene glycol #200 dimethacrylate as a crosslinking agent was removed from the monomer mixed solution. Ta. The amount of triboelectric charge of this developer was +19.8 μc/g. When a test similar to that in Example 1 was conducted using this developer, the initial image had similar fixing properties and image quality, and the image density was good at 1.2. After the idle rotation, the image density decreased (0.6) and fog occurred. The amount of triboelectric charge of the developer had increased to +27.5 μc/g, and thin streak-like fusion was occurring on the developing sleeve. Further, when the surface of this developer was observed using an electron microscope, some peeling of the shell was observed. Example 2 Granulation was performed in the same manner as in Example 1 using 40 parts of Hiwax 200p (manufactured by Mitsui Petrochemicals), 60 parts of Parain Wax 155, and 5 parts of phthalocyanine blue. A core material with a particle size of 10.2±4.6μ was obtained. This was cooled to -20°C. Styrene 40g Methyl methacrylate 30g Divinylbenzene 5g Diethylaminoethyl methacrylate-styrene copolymer (molar ratio 1:9) 3g Benzoyl peroxide 1.4g Dimethylaniline 0.8g Monomers were prepared in the same manner as in Example 1. A mixed solution was prepared, and 100 g of the cooled core material obtained above was mixed at -20°C to obtain a slurry. On the other hand, 2 g of hydrophilic silica was dispersed in 1 part of water using the homomixer described above and kept at 5°C. The above slurry was introduced into this system and polymerized in the same manner as in Example 1. Hydrophilic silica on the particle surface was dissolved and removed with a 5% aqueous sodium hydroxide solution, washed with water and dried to obtain capsule particles. To 90g of these capsule particles, 0.54g of hydrophobic colloidal silica was externally added and mixed in 200~
A developer was prepared by mixing 300 mesh of iron powder at a weight ratio of 1/9 to develop a latent image with a negative electrostatic charge, which was then transferred onto high-quality paper and fixed under the fixing conditions of Example 1. , the fixing properties are good, and the image density is
1.3, and a clear inverted image with no fog was formed. Next, we conducted a continuous durability test on 3,000 sheets of A4 paper at room temperature and humidity, and found that there was no contamination or adhesion on the developing sleeve, photoreceptor, or carrier surfaces, and good images without fog were constantly produced without change. Obtained. Comparative Example 2 A developer was obtained by performing encapsulation, external addition treatment, and carrier mixing in the same manner as in Example 2, except that 5 g of divinylbenzene as a crosslinking agent was removed from the monomer mixed solution. When a test similar to that in Example 2 was conducted using this developer, the initial image was as follows.
Although the fixability image density and image quality were both good,
In a continuous durability test of A4 size sheets, the developing sleeve was contaminated and fused to the photoreceptor surface after approximately 900 sheets, resulting in a decrease in image density and background stains due to poor cleaning, which revealed poor durability. . Comparative Example 3 A capsule toner was produced in the following manner using chlorinated paraffin Empara K-50 (manufactured by Ajinomoto Co., Ltd.) in place of Hiwax 200 and Paraffin Wax 155, which were the core materials of Example 2. Chlorinated paraffin Empara K-50 100g Phthalocyanine blue 5g Styrene 40g Methyl methacrylate 30g Divinylbenzene 5g Diethylaminoethyl methacrylate-styrene copolymer (molar ratio 1:9) 3g Benzoyl peroxide 1.4g Dimethylaniline 0.8g The above materials - When mixed at 20°C, an oily substance in which the pigment phthalocyanine blue was dispersed was obtained.
Next, this oily substance was dispersed in 1 liter of water in which 2 g of hydrophilic silica was dispersed and adjusted to 5° C. using a homomixer, and the particle size was adjusted to 5 to 15 microns. The temperature of this dispersion was raised to 75° C. while stirring, and polymerization was carried out while maintaining this temperature. After the polymerization was completed, the same procedure as in Example 2 was carried out to obtain a toner.
When the surface of the toner was observed using an electron microscope, fine irregularities were observed. When image output was performed in the same manner as in Example 2, no problems were found in the initial image quality.
The image was good, but after a continuous durability test of 3,000 sheets, contamination and fusion were observed on the developing sleeve, photoreceptor, and carrier surfaces, and the image was blurred and the image was stained in the form of black dots in the background. occurred. Comparative Example 4 A 50% dispersion of styrene-butyl acrylate copolymer (70:30 weight ratio) emulsion obtained by crosslinking 100 g of the core material particles obtained in Example 2 with divinylbenzene
It was mixed with 200 g of the powder and dried using a spray dryer under conditions of a hot air inlet temperature of 160°C and an exhaust air outlet temperature of 110°C to obtain a capsule toner having a particle size of 7 to 15 microns. Images were produced in the same manner as in Example 2 using the obtained toner. The initial image was good, but after a continuous durability test of 3,000 sheets, contamination and fusion were found on the developing sleeve, photoreceptor, and carrier surfaces, and the image was blurred and black dots appeared in the background. It caused stains.

Claims (1)

[Claims] 1. A method for producing a capsule toner comprising a core material containing polyethylene and/or paraffin wax and an outer shell that covers at least a portion of the core material, wherein a vinyl monomer, a crosslinking agent, and a polymerization initiator are used. The core material is dispersed in a monomer system obtained by uniformly dissolving or dispersing the core material, or the surface of the core material is uniformly wetted with the monomer system, and then dispersed in an aqueous phase and polymerized. . A method for producing a capsule toner, which comprises covering at least a portion of the core material with an outer shell containing a crosslinked polymer of vinyl monomers.