JPS62253176A - Capsule toner for developing electrostatic image, its production and electrophotographic developing method using said toner - Google Patents

Abstract

PURPOSE:To obtain a capsule toner which has good fixability to plain paper, provides stable image density and image quality and obviates toner floculation and the change of electrostatic chargeability by forming core particles of a mixture contg. at least a coloring agent and soft solid material, sticking pulverized inorg. particles near to the surface thereof, and coating the particles with a shell material. CONSTITUTION:The core particles contg. at least the coloring agent and soft solid material are formed. The formed core particles 1 and the pulverized inorg. particles 2 are subjected to dry mixing so that the pulverized inorg. particles 2 are stuck near to the core particle surface. The surface thereof is coated with the shell material 3 by a phase sepn. method. Waxes, higher fatty acids and the metallic salts thereof or deriv., etc., are used for the soft solid material. Various dyes and pigments are used for the coloring agent. Alumina, titanium dioxide, barium titanate, etc., are used for the pulverized inorg. particles. Magnetic powder such as Fe, Co, Ni, magnetite or hematite is added at 14-70wt% to the core material 1 in the case of the magnetic capsule toner. Various resins are used for the shell material 3.

Description

Detailed Description of the Invention [Field of Application in Industry-1-] The present invention relates to a capsule toner used for developing an electrical latent image in electrophotography, electrostatic printing, or magnetic recording. relates to a microcapsule toner that can be fixed with low energy consumption.

[Prior Art] Conventionally, methods such as electrophotography, electrostatic printing, and magnetic recording have been widely used as methods for recording or copying large amounts of information.

In electrophotography, an electrical latent image is generally formed on a photoreceptor made of a photoconductive material by utilizing its photoconductivity, and then the latent image is developed using toner, and if necessary, It consists of the process of transferring a toner image to a transfer material such as paper and then fixing it to obtain a copy.

The electronic printing method, as proposed in Japanese Patent Publication No. Sho 42-14342, is a method in which a charged powder toner is guided to a recording material-L using an electric field, fixed thereon, and printed.

The magnetic printing method forms a magnetic latent image on a latent image carrier and develops it with toner powder containing a magnetic material.
This is a method of transferring and fixing a toner image onto a recording material.

In the method described above, an operation is performed to fix the obtained toner image on a recording medium such as paper in order to make it permanently storable. Energy consuming means such as heat or pressure are generally used to fuse toner images. The lower the energy consumption required for fusing, the simpler the fusing device, the smaller the control system, the less safety considerations, and the longer maintenance intervals. Even in that case, the toner can withstand the mechanical pressure that occurs when it is conveyed to the latent image surface, or the heat from heat generating parts such as the fixing system and drive system in the developing system.
It is necessary to maintain its performance even during storage without changing its development characteristics.

Lowering the melting point of toner to make it easier to fix,
The use of soft materials naturally has a limit in terms of durability. To overcome these limitations, there has been proposed a microcapsule toner in which soft core particles are coated with a hard resin, as disclosed in US Pat. No. 3,788,994. However, although this microcapsule toner exhibits high resistance to static pressure and performs well during storage,
It is brittle under dynamic pressure and tends to be destroyed gradually by friction, especially in a short period of time when the thermal environment is low or high. against friction.

Increasing the thickness of the outer shell to provide sufficient strength will degrade the fixing properties. Obtaining thick-film microcapsules is achieved by conventionally known microencapsulation methods.
If it takes a long time to encapsulate the toner, or if the toner is extremely small in size from a few grammes to a few tens of grammes, aggregates or particles consisting only of loose shell material are likely to be formed, which tends to deteriorate the toner's performance. Therefore, it is desired to develop a microcapsule toner that is covered with a thin shell material that does not impair fixability and has high strength.

[Problems to be Solved by the Invention] An object of the present invention is to provide a capsule toner that solves the above-mentioned problems.

SUMMARY OF THE INVENTION An object of the present invention is to provide a capsule toner that hardly deteriorates even when rubbed for a long time.

A further object of the present invention is to provide a capsule toner that can be fixed with low energy.

A further object of the present invention is to provide a capsule toner that does not cause caking during storage and has good fluidity.

The object of the present invention is to have good fixing properties on plain paper at a lower pressure than conventional ones, and to have a large number of external additives in the form of free particles such as fluidity imparting agents externally added to capsule toner. It is an object of the present invention to provide a capsule toner that is less likely to be reduced even when a sheet is copied, thus giving stable image density and stable image quality, and capable of stably exhibiting its intended effect.

Another object of the present invention is to provide a capsule toner that maintains its initial characteristics even when used continuously over a long period of time, and exhibits less toner aggregation and less change in charging characteristics.

Another object of the present invention is to provide a capsule toner that provides images with vivid colors.

Still another object of the present invention is to provide an efficient method for producing a capsule toner as described above.

[Means and effects for solving the problems] The capsule toner of the present invention was developed to achieve the above-mentioned object, and is composed of a core particle and a shell material covering the core particle.
It is characterized by having inorganic fine particles present near the surface of the core particle.

The method for producing a capsule toner of the present invention includes mixing resinous core particles and inorganic fine particles to make the inorganic fine particles reliable (including embedding) on the surface of the core particles, and forming core particles to which the inorganic fine particles are attached. It is characterized by being coated with shell material resin.

Specifically, the present invention includes a core particle containing at least a colorant and a soft solid substance, and a core particle containing 41% near the surface of the core particle.
An object of the present invention is to provide an encapsulator for developing an electrical latent image, which has inorganic fine particles coated thereon, and a shell covering the core particles and the inorganic fine particles.

Furthermore, in one aspect of the present invention, core particles are formed from a mixture containing at least a colorant and a soft solid substance, the formed core particles are mixed with inorganic fine particles, and the inorganic particles are formed near the surface of the core particles. To provide a method for producing a capsule toner for electrical latent image development, in which a core particle is formed to which fine particles are attached, and the core particle is coated with a shell by a phase separation method on the surface of the core particle to which inorganic fine particles are attached. be.

Another object of the present invention is to form an electrical latent image on a photoreceptor having an organic photoconductor; to develop the electrical latent image with an encapsulated toner, the encapsulated toner comprising a colorant and a soft solid material; A capsule for electrical latent image development, which has a core particle containing at least a core particle, an abrasive inorganic fine particle attached near the surface of the core particle, and a shell covering the core particle and the abrasive inorganic fine particle. An object of the present invention is to provide an electrophotographic developing method comprising the following steps: a toner; transferring the formed capsule toner image to a transfer material; and cleaning the surface of the photoreceptor after transfer with a blade cleaning means.

As schematically shown in FIG. 1, the microcapsule toner improves rigidity and heat resistance by filling the vicinity of the surface of the core particle 1 with inorganic fine powder 2, so even if the shell 3 is extremely thin, The capsule toner is resistant to friction during storage, agitation for development, or the transportation process, as well as frictional heat and heat generated from the device, and can maintain its original form and function well. This is because the thickness of the shell material is kept small, so it is less likely to become an obstacle when applying pressure uniformly, and the core material of the present invention has few substances that inhibit fluidity during pressurization. As a result, the energy consumption of the fixing tank can be kept low.

As the window material used in the present invention, a soft solid substance exhibiting favorable fixing properties is used. Such substances include waxes (beeswax, carnauba wax, microcrystalline wax, etc.), higher fatty acids (stearic acid,
palmitic acid, lauric acid, etc.), higher fatty acid metal salts (
aluminum stearate, lead stearate, barium stearate, magnesium stearate, zinc stearate, zinc palmitate, etc.), higher fatty acid inducers (methyl hydroxystearate, glyceryl monohydroxystearate, etc.), polyolefins (low Molecular weight polyethylene, low molecular weight polypropylene, polyethylene oxide, polyisobutylene, polytetrafluoroethylene, etc.), olefin copolymers (ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer) combination, ethylene-methacrylic acid ester copolymer, ethylene-vinyl chloride copolymer,
ethylene-vinyl acetate copolymer, ionomer resin, etc.), styrene resin [low molecular weight is polystyrene, styrene-butadiene copolymer (monomer weight ratio 5 to 30:95)
~70), styrene-acrylic compound copolymer, etc.]
, epoxy resin, polyester resin (acid value 10 or less),
Rubbers (inbutylene rubber, nitrile rubber, vinyl chloride, etc.), polyvinylpyrrolidone, polyamide, coumaron
Examples include indene resin, methyl vinyl ether-maleic anhydride copolymer, maleic acid-modified phenol resin, phenol-modified terpene resin, and silicone resin, and these can be used alone or in combination.

The soft solid substance contained in the core particles has a temperature of +00
It is preferable to contain waxes or low molecular weight polymers having a melt viscosity of 1 to 100 cps, preferably 1 to 30 cps, in an amount of 30 double stars or more, preferably 50 to 95% by weight.

The core material of the capsule toner of the present invention contains a colorant, and the colorant includes various dyes and pigments. Such dyes and pigments include, for example, carbon black, nigrosine dye, Rumpf black, Sudan black S
N, Firth i...Erow G, Benzidine Yellow, Pigment Yellow, India First Orange, Irgazin Red, Palanii Roaniline Red, )・
Luizine Red, Carmine FB, Permanent Bordeaux FRR, Pigment Orange R, Lysol Lett 2G, Lake Red C, Rhodamine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue, Pigment Blue, Prilliant.
Green B, Phthalocyanine Green, Oil Yellow GG, Zapon Fast Yellow CGG, Kayasera 1-Y983, Kayaset YG, Sumiplast Yellow GG, Zapon Fast Orange RR, Oil Scarlet, Sumiblast Orange G, Orazole Brown B, Pomelo First Scarlet CG, Eisensbiron Red BEH or Oil Pink OP can be applied.

When the capsule toner is used as a magnetic capsule toner, magnetic powder is mixed into the core material. The magnetic powder used is a substance that becomes magnetized when placed in a magnetic field, and includes powders of ferromagnetic metals such as iron, cobalt, and nickel, and alloys and compounds such as magnetite, hematite, and ferrite. The content of this magnetic powder is preferably 15 to 70% by weight, preferably 20 to 50% by weight, based on the weight of the capsule toner.

In order to improve the dispersibility of the magnetic powder in the core particles and the moisture resistance, it is preferable to use a magnetic powder that has been subjected to hydrophobization treatment. The hydrophobization treatment is performed by adding 0.01 to 5 parts by weight of a titanium coupling agent to 100 parts by weight of magnetic powder.
Hydrophobic treatment is performed using a treatment agent such as a silane coupling agent or an aluminum coupling agent. Generally, hydrophobization treatment involves stirring dried magnetic powder in various types of mills, and during stirring, a coupling agent dissolved in a coupling agent-soluble solvent such as toluene or benzene is sufficiently dispersed. This is done by dropwise mixing and reaction at high speed, followed by evaporation and removal of the solvent and reaction by-products.

As for the method of granulating the core material of the capsule toner of the present invention, a conventional pulverization method is not preferable because the core material binder is soft or has a low melting point, which tends to cause fusion and requires pulverization while cooling. A suitable method is to mix the binder and colorant in a molten state and then spray-cool them, or to disperse and suspend them in hot water, form particles, and then cool and solidify.

The core particles obtained by such a method have a shape similar to a pearl, and this is reflected in the shape of the capsule toner finally obtained, giving the capsule toner more durability against friction. The number of core particles is preferably 1~! Particles having a particle size in the range of 10 gm, more preferably 5 to 20 JLffi are preferred.

In the present invention, inorganic fine particles are externally added and mixed to the core particles obtained as described above, so that the inorganic fine particles are attached to the surface of the core particles.

Examples of the inorganic fine powder used in the present invention include alumina, titanium dioxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate,
Zinc oxide, silicic acid, clay, cloud I, wollastonite, diatomite, various inorganic oxides II, chromium oxide, cerium oxide, red iron, antimony trioxide, magnesium sulfuride,
Examples include powders or particles such as zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silica fine powder, silicate, silicon carbide, silicon nitride, boron carbide, tungsten carbide, titanium carbide, and molybdenum disulfide. As the inorganic fine particles, non-magnetic ones are usually used. These inorganic fine powders preferably have a hydrophobic group on their surface, for example, those treated with a hydrophobizing agent such as a silane coupling agent, a titanium coupling agent, silicone oil, or a silicone oil having an amine in the side chain. is good. As the inorganic fine particles, those having a smaller size than the core material particles are used, and those having a specific surface area of 0.5 to 500 m2/g, preferably 50 to 400 ff12/g by the BET method using N2 adsorption are preferably used. . Furthermore, as the inorganic fine particles, those that are substantially insoluble and resistant to water and organic solvents, and have thermal stability at temperatures up to 300°C are preferred.

According to the present invention, these inorganic fine powders are crushed into core particles, preferably at heated F (e.g. 40
(under heating at about ~50° C.), and is dry mixed. The core particles to which the inorganic fine powder is attached are then encapsulated. The additive amount used is in the range of 0.01% by weight or more, preferably 0.1 to 10% by weight, particularly preferably 0.2 to 5% by weight, based on the weight of the core particles. By such an external addition mixing operation, the inorganic fine particles are stuck to the surface or surface layer of the core particle in a state where it is embedded therein.

Even in such an external addition mixing operation, some inorganic fine particles may not adhere to the core particles and may simply be mixed with the core particles as free particles, but such inorganic fine particles that are not attached may also be In the subsequent encapsulation operation, it is incorporated into the shell material and serves to strengthen the shell material, so 1.
- The externally added mixture obtained as described above may be directly supplied to the encapsulation process.

The vicinity of the core particle surface in the present invention refers to a region where the inorganic fine particles are buried or semi-buried in the core particles by dry mixing the core particles and the inorganic fine particles, and is within 115 of the core particle diameter from the surface, preferably 1/10. This refers to the surface layer at a depth within It is preferred that 90% by weight or more of the inorganic fine particles, preferably 85 or more, are unevenly distributed near the surface.

The core particles to which the inorganic fine particles obtained as described above are attached are covered with a shell material.

As the shell material, known resins can be used, including resins made of the following monomers.

Styrene, p-chlorostyrene, p-dimethylamino-
Styrene and its substituted products such as styrene; acrylic acid or methacrylic acid such as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, N, N-dimethylaminoethyl methacrylate, etc. Esters of maleic anhydride or halfamides or diesterimides of maleic anhydride; nitrogen-containing vinyls such as vinylpyridine and N-vinylimidazole; vinyl acetals such as vinyl formal and vinyl butyral; vinyl chloride, acrylonitrile, vinyl acetate, etc. vinyl monomers; vinylidene monomers such as vinylidene chloride and vinyl fluoride; monomers such as polyesters, polycarbonates, polysulfonates, polyamides, polyurethanes, polyureas, epoxy resins, rosins, modified rosins, terpene resins, phenolic resins, Homopolymers, copolymers, or mixtures of aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, melamine resins, polyether resins such as polyphenylene oxide, or thioether resins can be used.

To obtain a capsule toner having an outer shell made of these polymers,
Although various encapsulation techniques can be utilized, phase separation methods are preferably used in the present invention. The phase separation method that can be preferably used in the present invention refers to a method that has extremely low solubility or substantially insolubility in the soft solid material forming the core particles of the solid capsule toner, and has very low solubility or substantially insolubility in the shell material. A dispersion is prepared by dissolving the shell material in a well-soluble solvent that exhibits good solubility, and dispersing the core particles in the solution of the well-soluble solvent in which the shell material is dissolved. -1- Feeding Soluble solvent refers to a method in which the shell material is precipitated on the surface of the core particle by gradually adding a poorly soluble melt to the shell material, which is uniformly mixed with the soluble solvent.

Examples of good solubility solvents include dimethylformamide, and examples of poor solubility solvents include water, methyl alcohol, ethyl alcohol, and hydrocarbons having 5 to 8 carbon atoms.

The obtained capsule toner of the present invention has a particle size of 0.05 to 1.0.
gm, preferably having an outer shell thickness of 0.1 to 0.13 p-m, and a volume average particle size of 1 to 50 gm, preferably about 5 to 20 gm, and the core particle surface It has a q form in which inorganic fine particles are present in the vicinity.

The capsule toner of the present invention has a volume resistivity of 1010ΩC.
It is preferable to have an insulation property of 1n or more, particularly 1012 Ωcm or more. The volume resistivity referred to here is determined by molding the toner at a pressure of 100 kg/cn+2, and adding +00 V/cn to this.
It is defined as the value calculated from the current value after 1 minute after applying an electric field of cm.

As mentioned above, the capsule toner of the present invention further contains carbon black, various dyes and pigments, hydrophobic colloidal silica, etc. for the purpose of charge control agent, flowability agent, coloring agent, etc. External additives can be externally added and mixed, and the effects of their addition can be stably exhibited. The capsule toner of the present invention may further include externally added abrasive inorganic fine particles, and metal oxides, nitrides, and carbides are preferably used as the abrasive inorganic fine particles. Specific examples of metal oxides include tin oxide, cerium oxide, zirconium oxide, titanium dioxide, zinc oxide, aluminum oxide, iron sesquioxide, calcium titanate, strontium titanate, and barium titanate; Examples of carbides include titanium tetranitride, boron nitride, silicon nitride, and titanium nitride; examples of carbides include boron carbide, silicon carbide, tungsten carbide, and titanium carbide. The abrasive inorganic fine particles of the present invention not only have the function of strengthening the capsule toner, but also have the main function of destroying a portion of the capsule toner during processes such as before image fixation, development transfer, and cleaning on the photoreceptor. If upward filming or fusion occurs, it is removed by the action of abrasive inorganic fine particles. A suitable amount of these external additive components is about 0.1 to 5 parts by weight per 100 parts by weight of the capsule toner.

According to the present invention, by coating core material particles to which inorganic fine particles are attached by external mixing with shell material resin, the inorganic fine particles can be firmly held and the effect can be stably exhibited over a long period of time. A capsule toner is obtained.

The capsule toner of the present invention can maintain its original form and function by withstanding frictional U force, frictional heat, and heat generated from equipment during storage or during stirring or transportation for development. Furthermore, it has the extremely useful property that the energy required for fixing can be kept low.

Further, the present invention is useful as a capsule toner for a developing method using a photoreceptor having an organic photoconductor. Photoreceptor using an organic photoconductor (hereinafter abbreviated as OPC photoreceptor)
is superior to photoreceptors using inorganic photoconductive materials such as selenium, cadmium sulfide, zinc oxide, or amorphous silicon as a photoconductive material in terms of film formability and light weight.

Conventionally, sensitivity was a problem, but by adopting an electrophotographic photoreceptor with a laminated photosensitive layer in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer, sensitivity to visible light and charge retention ability have been improved. Improvements have been made, including in terms of surface strength.

Such an electrophotographic photoreceptor is disclosed in US Pat. No. 383, for example.
No. 7851, No. 3871882, and the like.

However, since the charge transport layer forming the surface of an OPC photoconductor using an organic photoconductor contains a charge transport substance and a polymeric binder that cannot be used to form a film, toners or capsule toners using an organic resin binder cannot be used. There is a problem in that toner tends to adhere to the surface of the OPC photoreceptor compared to inorganic photoreceptors such as selenium and amorphous silicon.

In particular, when a pressure-fixable toner is used, since a soft material is inevitably used, the phenomenon in which the toner is attracted to the photoreceptor surface -L tends to occur significantly.

The capsule toner of the present invention has a structure in which a core particle in which abrasive inorganic fine particles are attached near the surface of the core particle is covered with a shell material, and the abrasive inorganic fine particles are firmly held and used effectively. However, the Okatsu microcapsule toner is reinforced with abrasive particles. For this reason, problems such as fusion of the capsule toner material due to destruction of the capsule toner on the OPC photoconductor, which was a problem especially in the combination of an OPC photoconductor using an organic photoconductor and a pressure-fixable capsule toner,
Not only does the phenomenon of filming become less likely to occur, but even if it does occur, by effectively utilizing the abrasive inorganic fine particles, it becomes possible to effectively eliminate its adverse effect on the development characteristics.

FIG. 4 shows an embodiment of the electrophotographic method used in the present invention.

Reference numeral 17 denotes a photosensitive drum (CDPC drum) made of an organic photoconductor, which rotates in the direction of an arrow 21. 18 is photosensitive drum 1
7, an exposure lamp for erasing the charge on the photosensitive drum 17 and measuring uniformity of charging; 19, a corona charger that can uniformly charge the photosensitive drum 17; 20, the photosensitive drum 17 uniformly charged by the charger 18; 22 is a developing machine for developing the latent image with the capsule toner according to the present invention; 23 is a developing machine for developing the latent image with the capsule toner according to the present invention; A transfer charger is used to transfer the developed image on the photosensitive drum 17 developed by the developing device 22 onto the transfer material 24, and 25 is a cleaning blade for cleaning the toner remaining after transfer on the photosensitive drum 17, as shown in the figure. It is installed in a direction opposite to the rotational direction 21 of the photosensitive drum. As the cleaning means, blade cleaning is preferable, and as the blade member, an elastic rubber member such as urethane rubber is preferable.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 Core material is Hiwax 200P (manufactured by Mitsui Petrochemical)
20 parts by weight, paraffin wax +55 CH4, M
(screw) 80 parts by weight, 5 parts by weight of phthalocyanine blue (1 part by weight)
By melt-mixing at 50°C, granulating with a spray dryer, and dry classification, the particle size is 1000 m±5.
Op, Ia, and spherical core particles were obtained.

On the other hand, while stirring 100 parts by weight of silica fine powder (specific surface area: approximately 130 m?/g) synthesized by a dry method, amino-modified silicone oil having an amine in the side chain (25°C
viscosity of 70 cps, amine equivalent of 830) was sprayed and the temperature was maintained at approximately 250° C. for 60 minutes.

1 kg of the core particles and 20 g of the treated silica fine powder were placed in a Henschel mixer 10B model (Mitsui Miike Seisakusho) at a temperature of 45°C and a rotation scale of 10 (approximately 3300 to 3500 rpm).
, p, m,) for 4 minutes. Next”
- The externally attached mixture of core particles and treated silica fine powder is separated from the organic phase by a phase separation method (dispersing the core particles in a solution of dimethylformamide in which the shell material is dissolved, and adding water to the dispersion). The particles were coated with a styrene-dimethylamine ethyl methacrylate (mole ratio 90/10) copolymer to a film thickness of about 0.4 gts by gradual addition to obtain encapsulated particles. 1.0 g of the silica fine powder treated with the above amine-modified silicone oil was added to 100 g of the obtained encapsulated particles.
g was further externally added and mixed at room temperature to obtain a capsule toner.

When this capsule toner was cut with a microtome and observed with a transmission electron microscope, it was found that in addition to silica on the surface of the shell material, fine silica powder was found at the interface between the core material and shell material of the capsule toner and inside the core particles (near the surface). was confirmed to exist.

For 12g of this capsule toner, 88g of carrier (EFV250/400 made by Nippon Steel Powder) was added. h
A latent image with a negative electrostatic charge was developed using a L-c developer and then transferred to high-quality paper. When the transfer paper with the toner image was passed through a pressure fixing machine consisting of two wooden pressure rollers that could apply pressure from both ends, almost perfect fixing was achieved with a linear pressure of 10 kg/cm. The image density was 1.8, and a clear reverse image without fog was formed, which was good. Furthermore, when a continuous durability test was conducted on 3,000 sheets of A4 size originals, the image density was 1.4 or more -1-, and good images without fog were stably obtained.

When the toner surface before and after the durability test was observed using a scanning electron microscope, no significant difference was observed in the amount of silica externally added to the capsule toner.

Comparative Example 1 The same operation as in Example 1 was repeated except that the silica fine powder treated with amine-modified silicone oil was not externally added and mixed into the core particles.

The initial image had an image density of 1.5, which was the same as in Example 1, and a clear reversed image without fogging was formed, and the fixability was also good. However, in a continuous durability test of 3,000 sheets, , the density decreases with the number of durability test sheets (image density 1.0) l,,
Fog also occurred. Filming on the photoreceptor surface and some fusion at both ends of the developing sleeve were observed, and when the toner surface was observed using a scanning-type molecular microscope, it was found that the silica added externally to the capsule toner was lower than before after the durability test. A clear decrease in the amount was observed.

Example 2 As an external additive for the core particles of Example 1, instead of silica fine powder treated with amine-modified silicone oil,
Example 1 except that titanium oxide (average particle size Q, I JLm) treated with 5% by weight of impropoxy titanium triisostearate (Nippon Soda type TTS) was used.
A capsule toner was prepared in the same manner as above. A copying test was conducted in the same manner as in Example 1, and good results were obtained. After the durability test, the amount of silica externally added to the capsule toner was slightly reduced, but it did not affect copying.

Example 3 Instead of the silica fine powder treated with amino-modified silicone oil as an external additive for the core particles of Example 1, 3
A capsule toner was prepared in the same manner as in Example 1, except that silicon carbide (average particle size 0.38 pLm) treated with % by weight of isopropoxytitanium triisostearate was used.

Example 4 30 parts by weight of low molecular weight polyethylene wax with a molecular weight of 3000, 70 parts by weight of 155'F paraffin wax and F
A pre-dispersion of 470 parts by weight of e3O was dispersed, mixed and kneaded using an attritor at 140°C. Next, the obtained molten mixture was sprayed into air at 50°C from a two-fluid nozzle using air at 180°C, and collected by a cyclone to obtain spherical magnetic core particles having a size of 1 to 20 μm.

1000 parts by weight of the core particles obtained above and titanium oxide (
BET specific surface area 3!3.7m? /g, particle size 0.047p
m) 20 parts by weight and Henschel mixer type 10B (
(manufactured by Mitsui Miike Seisakusho), the mixture was stirred and mixed for 2 minutes at a rotation scale of 10. Next, 100 parts by weight of this mixture was mixed with 10 parts by weight of dimethyl lj aminoethyl methacrylate-1/-styrene copolymer (copolymerization ratio 10:90; molecular weight 25,000) and 400 parts by weight of dimethyl formamide (abbreviated as DMF). The dimethylaminoethyl methacrylate-styrene copolymer is dispersed in a solution dissolved in 100% of the total amount of dimethylaminoethyl methacrylate, and water is added dropwise while stirring to phase-separate the dimethylaminoethyl methacrylate-styrene copolymer, surrounding the core material particles, and then hardening by adding water. As a result, capsule toner single particles having a shell material layer having a thickness of approximately 0.4 gm and containing approximately 20% by weight of titanium oxide were obtained.

The obtained toner exhibited positive chargeability, and when it was filled into a developing machine for electronic copying*PG-+2 (manufactured by Canon) equipped with an OPC photoreceptor and a urethane rubber blade cleaning member, and discharged from both sides, A transferred image was obtained which was clear and had no fog, and a high image density.

When testing the fixability of this unfixed image, it was found that the linear pressure was 12k.
Pressure fixing was possible at g/cm, and sufficient heat fixing was possible at 80° C. when left in a constant temperature bath. Here, the fixing property is determined by printing the fixed image of "1-page paper" once back and forth through Silpon paper C (Haga Yoshiten) with a basis weight of 20 g/m2 using a 50 g weight with a base area of 1 cm2. The point at which the difference in toner image density before and after rubbing and rubbing was 5% or more was defined as the fixing point.

The structure of the developing section of the developing machine used is schematically shown in FIG. 2. The distance between drum 11 and sleeve 12 is 3
00 p, m, the distance between the sleeve 12 and the blade 14 is 100 p, m, the fixed magnetic pole 13 is the same as the blade 1
4 was used, showing a maximum of 650 Gauss at the opposite part. The sleeve 12 is 66mm7s in the forward direction of the drum 11.
It rotated at a speed of ec.

There is a frequency of 1.6k between the drum 11 and the sleeve 12.
Hz, Vp-p (peak-to-peak voltage)], 3
Applying an AC bias of kV and a DC bias of -400V, the drum 11. , 118 parts is 1700 parts for the photoconductor of
An electrostatic image of V was formed.

As a durability test, copying operations were repeated using a blank original with almost no toner consumption, and toner was collected every 6 hours using a Coulter Counter Model TA-
II (manufactured by Coulter Counter Co., Ltd.), the particle size was inspected, and as shown by curve A in Figure 3, there was almost no change in particle size from the initial stage even after 24 hours, and when the original image was copied, the copied image was similar to the initial It maintained the same sharpness and image density. No fusion was observed in the seal portion in the developing machine or the developing sleeve.

This toner was filled into a cylinder with a diameter of 50 mm to a thickness of 500 mm, and left at a temperature of 50°C for one week, but no caking was observed. Using this toner, copying operations were performed in the same manner as above. A good image was obtained.

Comparative Example 2 A capsule toner was obtained in the same manner as in Example 4 except that titanium oxide was not used. This capsule toner was used in Example 4.
An image was produced in the same manner as above, and the initial image was clear and had no fog, and the image density was high. The fixing performance also has a linear pressure of 12 kg/
Pressure fixing was possible at Cm, and sufficient heat fixing properties were exhibited at 80° C., and no difference from the capsule toner of Example 4 was observed.

Using this capsule toner, a durability test was conducted in the same manner as in Example 4, and after about 6 hours, a large amount of fused capsule toner was visibly observed in the area in contact with the rotating sleeve 2 at the sealing part of the developing device. After 24 hours, the sleeve no longer rotated smoothly, and the capsule toner at the end of the sleeve came into contact with the latent image support drum, making it impossible to maintain a proper gap. The developability of the capsule toner also deteriorated, and the image density also decreased, resulting in a rough image. At this time, toner fused substances that did not pass through the 100-mesh sieve were observed in the capsule toner in the hopper, and there were streak-like areas where toner was not coated on the developing sleeve-1.

Graph B in FIG. 3 shows the change in the particle size of the toner in the sleeve in the hopper measured by the coulter counter. Particle size measurement was performed by putting the collected toner into saline solution containing a surfactant and ultrasonically dispersing it for 5 seconds.

At the start, the volume average diameter increased to 18.7 JLm after 24 hours, but when the ultrasonic dispersion time was increased to 5 minutes or more, the particle size returned to the initial particle size. Ta. When a fluidizing agent such as hydrophobic colloidal silica is added to the toner in the hopper and mixed with a Henschel mixer, the particle size returns to the original size except for some fused pieces, but the developability deteriorates. He no longer recovered.

Examples 5 to 9 Alumina, zirconia, silicon carbide, in place of titanium oxide,
A capsule toner was obtained in the same manner as in Example 4 except that titanium nitride and boron nitride were used. Table 1 shows the characteristics and copying test results of each capsule toner obtained. Table 1 also lists Example 4 and Comparative Example 2.

Example 1O After mixing and melting the above mixture using an MKM mixer (manufactured by Ogawa Seisakusho), an attritor (
(manufactured by Mitsui Miike Seisakusho) and dispersed for 5 hours at 200 r, p, IIl, 7 parts by weight of N-dodecyldimethylamine was added and further dispersed for 30 minutes to prepare a melt.

20 grams of water and 40 g of silica (Aero Seal 1200) were placed in a 20-ton Ajihomo mixer (manufactured by Tokushu Kika) and heated to 95° C. using a heating jacket to prepare a dispersion medium. 2 kg of the melt was added to this and granulated by stirring at a circumferential speed of 20 m/see, and the number average particle diameter was ? , B pLm , weight average particle diameter 12.3g
It became fine particles of m. This was put into a container containing 30 kg of ice to rapidly cool it, and then 40 kg of caustic soda was added to this liquid.
After stirring for 24 hours, filtering using a centrifuge and washing with water were repeated to remove residual silica and caustic soda from the dispersion. After that, the core was dried in a ventilation dryer at 40°C. Particles were obtained.

When the surface and section of this core particle were observed using an electron microscope, it was found that there was no magnetic material on the surface, and the particles were fine particles with magnetic material sufficiently dispersed inside. In addition, 1 kg of this core particle
20g of wet silica was heated to 41°C using a Henschel mixer.
By externally adding and mixing at ℃, 10 g of titanium dioxide having a particle size of 0.20 g ta was attached to the core particles. The above-mentioned core particles were added to a solution in which 12 g of styrene/diethylaminoethyl methacrylate copolymer as a shell material resin was dissolved in 1 kg of MF, and slowly stirred thoroughly with a homomixer (manufactured by Tokushu Kika). Then, cold water was added dropwise, and when the precipitation of the shell material was completed, it was filtered using a centrifuge or a filter, washed with water repeatedly, and thoroughly dried at 40°C. When this was observed using an electron microscope, it was found that a microcapsule toner was obtained which was uniformly covered with a shell material and had titanium oxide present near the surface of the core particle.

0.5 g of wet silica was added to 100 g of the obtained capsule toner powder, stirred, sieved, and OPC
When a modified Canon PC-20 machine equipped with a photoreceptor and a cleaning blade made of urethane rubber was used, high-quality images were continuously obtained in a continuous copying test of 3,000 sheets.

Example 11 The mixture described above was melted and dispersed using an MKM mixer and an attritor in the same manner as in Example 10, and then 5 parts by weight of N-dodecyldimethylamine was added and further dispersed for 30 minutes. Next, in the same manner as in Example 1O, 20 grams of water and silica (Aero Seal 1
300) 2 kg of the above melt was put into a dispersion medium that had been preheated to 95°C, and the circumferential speed was 17.5 m.
When granulation was carried out by stirring at /sec, the number average particle size was 7.8 ILm and the weight average particle size was 12.5p in about 20 minutes.
m fine particles were obtained. This was post-treated by the same means as in Example 10 and then dried to obtain core material particles. When this particle was similarly observed, it was found that the magnetic particles were not present on the surface of the core particle and were well dispersed within the core particle.

Hydrophobic dry silica was attached to the core particles by a method similar to that shown in Example 10, and then encapsulated and post-treated to obtain a dried microcapsule toner. When this was observed using an electron microscope, it was found to be a microcapsule toner in which silica was attached near the surface of the core particle.

[Brief explanation of drawings]

Among the accompanying drawings, Figure 1 is a diagram schematically showing a cross section of the capsule toner of the present invention, and Figure 2 is a diagram for evaluating the durability of magnetic capsule toners according to uninvented examples and comparative examples. 3 shows a schematic cross-sectional view of the main parts of the developing device used in
The figure is a graph showing the change in capsule toner particle size during the durability test, and FIG. 4 is a schematic diagram showing an example of the electrophotographic method used in the present invention. l... Core particle, 2... Inorganic fine powder, 3... Shell, 1
DESCRIPTION OF SYMBOLS 1... Drum, 12... Sleeve, 13... Fixed magnetic, 14... Blade, 15... Capsule toner, 16... Container wall, 17... OPC drum, 18...
・Exposure lamp, 19...Corona charger, 20...Document exposure, 21...Drum rotation direction, 22...Developer, 23...Transfer charger, 24...Transfer material, 25・・・
・Cleaning blade.

Claims (3)

[Claims] (1) Core particles containing at least a colorant and a soft solid substance, inorganic fine particles attached near the surface of the core particles by dry mixing with the core particles, and coating the core particles and the inorganic fine particles. A capsule toner for electrical latent image development, characterized in that it has a shell of: (2) Core particles are formed from a mixture containing at least a colorant and a soft solid substance, and the formed core particles are dry mixed with inorganic fine particles to adhere the inorganic fine particles near the surface of the core particles. A method for producing a capsule toner for electrical latent image development, which comprises forming a core particle and covering the surface of the core particle to which inorganic fine particles are attached with a shell material by a phase separation method. (3) forming an electrical latent image on a photoreceptor having an organic photoconductor; developing the electrical latent image with a capsule toner, the capsule toner comprising a core containing at least a colorant and a soft solid material; An electrical latent image comprising particles, abrasive inorganic fine particles attached near the surface of the core particles by dry mixing with the core particles, and a shell covering the core particles and the abrasive inorganic fine particles. An electrophotographic development method comprising the following steps: a capsule toner for development; transferring the formed capsule toner image to a transfer material; and cleaning the surface of the photoreceptor after the transfer with a blade cleaning means.