JPH0814726B2 - Toner for electrophotography - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a toner used for converting a latent image formed in a recording method of electrophotography into a visible image.

BACKGROUND OF THE INVENTION As a fixing method of a toner image in a recording method such as an electrophotographic method, there are known three kinds of methods: heat fixing, solvent fixing and pressure fixing. Due to environmental problems and the like, a heat fixing method and a pressure fixing method which do not use a solvent are often used these days.

In the heat fixing method, a toner composed of a coloring material and a binder (binding component) has been conventionally used. The above-mentioned toner is used in the pressure fixing method, but in recent years, the use of encapsulated toner in which the toner is contained in microcapsules has been studied.

The capsule toner is a microcapsule form obtained by forming a resin outer shell having a property of being destroyed by application of pressure around a core substance containing a coloring material such as carbon black and a binder such as a polymer and an oily solvent. Toner. A normal toner is a toner containing a coloring material such as carbon black dispersed in a binder.

[Prior Art and Problems] Conventionally, a toner having an insulating surface has been generally used as a developer for electrophotography, but recently, a toner surface having an appropriate positive or negative triboelectrification property is provided. Toner has been developed.

That is, the toner is charged by rubbing the carrier particles such as iron powder or fur or the like with the toner,
The toner used in the electrophotographic method of attracting the charged toner to the latent image may have a negative or positive frictional charging property corresponding to the charging property of the latent image which is defined as positive or negative depending on the type of the device. Will be needed.

As a method of imparting triboelectricity to a toner, a method of mixing a charge control agent with a resin or the like when forming the toner and dispersing the mixture inside the toner is used. As the charge control agent, nigrosine or the like is generally used to impart positive triboelectricity, and a metal complex dye or the like is used to impart negative triboelectricity. Of these charge control agents, only those present on the toner surface act as a charge control agent.

Further, in the capsule toner, since it is difficult for the above charge control agent to effectively exist on the surface of the capsule toner, it has been attempted to impart triboelectric chargeability by the resin forming the outer shell of the capsule toner. That is, positive,
It is an attempt to form a capsule toner outer shell by using a resin having a desired triboelectricity, which is negative or has a high triboelectricity, thereby obtaining the desired triboelectricity of the capsule toner. However, the resin suitable for obtaining the desired triboelectrification property is such that other properties required for the outer shell of the capsule toner, for example, hardness and denseness of the resin that contributes to storage stability and pressure fixability are possible. There is a problem that the performance such as elasticity of is not sufficient.

As another method for imparting triboelectrification to the capsule toner, there is known a method in which a charge control group or a polymer having the charge control group is bonded to the outer shell surface of the capsule toner by a chemical bond. However, with this method, the efficiency of the above reaction on the surface of the outer shell is low, and therefore the triboelectric charging property obtained is not practically sufficient.
The same applies to the case where the charge control group is attached to a normal toner by a chemical bond as described above.

On the other hand, as a simple method of imparting triboelectrification to the capsule toner, a method of imparting triboelectrification by attaching a powdery charge control agent such as silica fine powder to the surface of the capsule toner is used.

However, according to the study by the present inventor, it is said that the capsule toner on the surface of which the charge control agent such as silica fine powder is applied is likely to be detached or peeled off during storage or during long-term operation. There's a problem. Furthermore, when silica fine powder is used as the charge control agent,
It is impossible to impart arbitrary triboelectrification to the capsule toner, and its performance is limited.

[Object of the Invention] It is an object of the present invention to provide a toner having a novel form.

Further, the present invention provides a toner capable of imparting desired triboelectric chargeability and having improved stability of triboelectric chargeability, and further excellent in fluidity and storage stability. With the goal.

SUMMARY OF THE INVENTION The present invention is at least selected from the group consisting of metal oxides, carbonates and silicates in which a chain polymer having a charge control function is bonded to the surface of toner particles by graft polymerization. An electrophotographic toner is characterized in that one kind of inorganic fine particles are attached or contained therein.

[Advantages of the Invention] The toner of the present invention has, on the surface of the toner, inorganic fine particles to which the polymer having a group having a charge controlling function is bound by graft polymerization. This makes it possible to obtain excellent triboelectricity and fluidity and always a good visible image, and the performance thereof hardly changes even after long-term use.

Further, by selectively using a compound having a polymerizable unsaturated bond used for graft polymerization on the surface of the inorganic fine particles, the triboelectrification property of the toner is positively, negatively, or the desired triboelectrification property with respect to the strength of the electrification property is obtained. Can be given.

In particular, when the surface of the inorganic fine particles is treated with a coupling agent having a vinyl group, it is possible to effectively carry out the graft polymerization by a usual radical polymerization reaction. This strengthens the bond between the polymer and the inorganic fine particles, so that the storage stability thereof is significantly improved.

[Detailed Description of the Invention] The toner of the present invention comprises at least one kind selected from metal oxides, carbonates and silicates having a chain-like polymer having a charge control function bonded to the surface of toner particles. It is characterized in that inorganic fine particles are attached or contained.

The toner of the present invention may be either a capsule toner or a normal toner. Particularly, it is highly useful for capsule toners in which it is relatively difficult to effectively apply the charge control agent.

 First, the capsule toner will be described.

 The capsule toner is usually manufactured as follows.

In producing the capsule toner, the microcapsules can be produced according to a usual method using the raw materials usually used for producing the microcapsules.

That is, a method for producing a capsule toner by forming a resin outer shell having a property of destroying by applying pressure around a core material containing a coloring material such as carbon black, and a polymer, a binder such as an oily solvent, It is already known as mentioned above.

In the production of the capsule toner, an outer shell was formed around the core substance by utilizing a microcapsule production method such as an interfacial polymerization method or an external polymerization method in an aqueous liquid, particularly a microcapsule production method based on a polymerization reaction. Later,
A known method such as a method of washing with water can be used.

Examples of the polymer that can be used as a binder component in the encapsulated toner include the following compounds.

Polyolefin, olefin copolymer, styrene resin, styrene-butadiene copolymer, epoxy resin, polyester, rubber, polyvinylpyrrolidone, polyamide, coumarone, indene copolymer, methyl vinyl ether / maleic anhydride copolymer, amino resin, polyurethane, polyurea , Acrylic acid ester homopolymers or copolymers, methacrylic acid ester homopolymers or copolymers, copolymer oligomers of acrylic acid and long-chain alkyl methacrylate, polyvinyl acetate, polyvinyl chloride.

Particularly preferable as the above-mentioned binder polymer is a homopolymer or copolymer of acrylic acid ester, a homopolymer or copolymer of methacrylic acid ester, or a styrene-butadiene copolymer.

Examples of the oily solvent that can be used as a component of the binder include a high-boiling point solvent having a boiling point of 150 ° C. or higher (hereinafter also simply referred to as a high-boiling point solvent) capable of dissolving or swelling the above-mentioned polymer and substantially dissolving the above-mentioned polymer. Alternatively, an organic solvent which does not swell and has a boiling point within the range of 100 to 250 ° C. (hereinafter, also simply referred to as a low boiling point solvent) can be mentioned. An example of this high boiling point solvent is described below.

Phthalates (eg, diethyl phthalate, dibutyl phthalate); Aliphatic dicarboxylic acid esters (eg, diethyl malonate, dimethyl oxalate); Phosphates (eg, tricresyl phosphate, trixylyl phosphate); Citric acid esters (eg, o-
Acetyl triethyl citrate, tributyl citrate); benzoic acid esters (eg, butyl benzoate,
Hexyl benzoate); Aliphatic acid esters (eg, hexadecyl myristate, dioctyl adipate); Alkyl naphthalenes (eg, methyl naphthalene, dimethyl naphthalene, monoisopropyl naphthalene, diisopropyl naphthalene); Alkyl diphenyl ethers (eg, o-, m-, p-methyldiphenyl ether);
Amide compounds of higher fatty acids or aromatic sulfonic acids (eg, N, N-dimethyllauroamide, N-butylbenzenesulfonamide); trimellitic acid esters (eg,
Trioctyl trimellitate); diarylalkanes (eg, diarylmethane such as dimethylphenylphenylmethane, 1-phenyl-1-methylphenylethane,
1-Dimethylphenyl-1-phenylethane, 1-ethylphenyl-1-phenylethane and other diarylethanes), chlorinated paraffins.

Specific examples of the low boiling point solvent include an aliphatic saturated hydrocarbon or an organic liquid mixture containing an aliphatic saturated hydrocarbon as a main component.

The binder is preferably a composition containing a polymer, a low boiling point solvent and a high boiling point solvent.

Black toners such as carbon black and grafted carbon black are generally used as coloring materials for electrophotographic toners, but various chromatic colorants such as blue, red and yellow are also used. ing. These coloring materials can also be used in the capsule toner.

The core substance of the encapsulated toner may contain magnetic particles. As the magnetic particles, known magnetic particles for magnetic toner (magnetizable particles) can be used. Examples of such magnetic particles include cobalt, iron,
Alternatively, magnetic particles made of a simple metal such as nickel, an alloy, or a metal compound can be used. In addition,
When colored magnetic particles such as black magnetite are used as the magnetic particles, the colored magnetic particles such as magnetite can also be used as a component that serves both as the magnetic particles and the coloring material.

The type of resin forming the outer shell of the capsule toner is not particularly limited, but in consideration of the properties as the capsule toner, the outer shell resin is preferably polyurea, polyurethane, polyamide, polyester or epoxy resin. These resins can be used alone or as a mixture as a resin for forming an outer shell. And, the capsule toner of the present invention is composed of a composite wall containing at least one of a polyurea resin, a polyurethane resin, and a polyamide resin, the strength of the outer shell,
It is particularly preferable in consideration of flexibility and the like. It is also preferable to use a viscosity preventive agent such as silicone oil in combination.

In the toner of the present invention, it is necessary for the surface of the toner particles to have inorganic fine particles having a chain polymer having a charge control function bonded to the surface thereof attached or contained. As the inorganic fine particles, at least one selected from metal oxides, carbonates and silicates is used.

Examples of the metal oxide of the inorganic fine particles include silica, magnesia, alumina, titanium dioxide and the like, examples of the carbonate include calcium carbonate, magnesium carbonate and the like, and examples of the silicate include calcium silicate, Examples thereof include sodium silicate and aluminosilicates. Among such inorganic fine particles, silica and titanium dioxide are preferable. Further, the average primary particle diameter of these is preferably 1 mμ to 1000 mμ.

Inorganic fine particles are 0, based on the total weight of the capsule toner.
It is preferably contained or attached in the range of 1 to 5.0 wt%, particularly preferably in the range of 0.5 to 3.0 wt%.

In order to graft-polymerize the above-mentioned inorganic fine particles with a compound having a group capable of imparting triboelectricity and a polymerizable unsaturated bond, the following method can be used, for example.

Graft-polymerizing polyacrylic acid or the like in the presence of tetravalent cerium ions in an aqueous medium to bond a chain polymer to a nylon capsule is described in Polymer Preprints, Japan. 33
Vol. 7, No. 7, p. 1859 (1984), it is described in the research report "Membrane Permeability Control Using Surface Graft Capsule Membrane".

The method of graft polymerizing a chain polymer onto the inorganic fine particles of the present invention basically complies with the description of these research reports. Further, the morphology of the chain polymer on the surface of the obtained inorganic fine particles basically has a morphology similar to that described in the research report.

That is, first, the inorganic fine particles are dispersed in an aqueous dispersion.

Then, a compound having a group capable of imparting triboelectricity and a polymerizable unsaturated bond and a tetravalent cerium compound are added to the aqueous dispersion to perform graft polymerization on the surface of the inorganic fine particles. Water is usually used as the medium of the aqueous dispersion.

Examples of the tetravalent cerium compound used include cerium ammonium sulfate and cerium ammonium nitrate.

The tetravalent cerium compound is usually used in the range of 0.05 to 0.0005 mol per mol of the compound having a polymerizable unsaturated bond. It is particularly preferable to use it within the range of 0.05 to 0.01 mol.

The graft polymerization reaction of the compound having a polymerizable unsaturated bond onto the surface of the inorganic fine particles, which is carried out in the presence of the tetravalent cerium compound, does not particularly require heating. Therefore, the reaction can be carried out at room temperature or by heating. The reaction time is usually 0.1 to 5 hours.

The reaction is preferably performed in the presence of dilute nitric acid because the stability of the tetravalent cerium compound is increased.

In addition, in the above reaction, preferably before the above reaction, a compound having two or more polymerizable unsaturated bonds and a tetravalent cerium compound are added to the inorganic fine particle dispersion liquid to form a polymerizable unsaturated on the inorganic fine particle surface. It is better to graft-polymerize a compound having two or more bonds under the above reaction conditions.

As a result, a vinyl group is provided on the surface of the inorganic fine particles, and a compound having a polymerizable unsaturated bond and a group capable of imparting the triboelectric charging property to the vinyl group can be graft-polymerized in the same manner as above.

The graft polymerization on the vinyl group does not need to use a cerium compound and can be carried out by using a radical reaction initiator or a redox type initiator shown below.

Examples of compounds having two or more polymerizable unsaturated bonds include polyhydric alcohol polyacrylates (ethylene glycol diacrylate, trimethylolpropane triacrylate, etc.), polyhydric alcohol polymethacrylates (ethylene glycol dimethacrylate, trimethylolpropane). Trimethacrylate, etc.), reaction products of acrylic acid with amines having two or more acrylic groups, reaction products of methacrylic acid with amines having two or more methacrylic groups, polyvinyl ethers of polyhydric alcohols ( Ethylene glycol divinyl ether), polyvinyl ester of polycarboxylic acid (divinyl succinate, divinyl succinate, etc.), aromatic compound having two or more vinyl groups (divinylbenzene, etc.) .

Then, a compound having a group capable of imparting triboelectricity and a polymerizable unsaturated bond is a substituent having a Hammett substituent constant (δ) within a specific range in order to impart good triboelectricity to the inorganic fine particles. It is preferable to use a compound having a polymerizable unsaturated bond having a group (or a substituent atom, and the expression "substituent" will be generically referred to hereinafter unless otherwise specified).

That is, a compound having a reactive double bond having a substituent having a Hammett substituent constant of 0.4 or more or a substituent having a substituent position of 0 or less at either the meta position or the para position is usually used.

Hammett's substituent constant (δ) is capable of producing inorganic fine particles having negative triboelectricity by graft-polymerizing a compound having a substituent of 0.4 or more and a polymerizable unsaturated bond on the surface of the inorganic fine particles. . By using the toner to which the inorganic fine particles are adhered or contained, a positively charged electrostatic latent image can be developed. A group having a Hammett substituent constant of 0.4 or more is generally an electron-withdrawing group, and examples of such a group include a nitrile group (-
CN), fluorine atom and cyano group.

On the other hand, a positive triboelectric charging property can be obtained by attaching or containing fine inorganic particles having a Hammett substituent constant of 0 or less and a compound having a polymerizable unsaturated bond graft-polymerized on the surface thereof. It is possible to manufacture a toner having the same. By using this toner, a negatively charged electrostatic latent image can be developed. A group having a Hammett substituent constant of 0 or less is generally an electron-donating group, and examples of such a group include an amino group and a pyridyl group.

Examples of the compound capable of imparting negative triboelectricity to the surface of the inorganic fine particles, that is, a compound having a polymerizable unsaturated bond having an electron-withdrawing group include (meth) acrylonitrile, (meth) acrylic acid and vinyl fluoride. Can be mentioned.

Further, examples of the compound capable of imparting a positive triboelectric charging property to the toner, that is, a compound having a polymerizable unsaturated bond having an electron donating group include vinylpyridines (2-vinylpyridine, 5-methyl-2). -Vinyl pyridine, 5-
Ethyl-2-vinylpyridine, etc.), (meth) acrylic acid esters (dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc.), N-vinylimidazoles (N-vinyl-2-imidazole, N-vinyl-2, 4-dimethylimidazole, etc.), methyl methacrylate, diacetone acrylamide, vinylcarbazole and the like.

Considering the characteristics of the toner, among the above compounds,
In particular, acrylonitrile, vinyl pyridines, amino group-containing (meth) acrylic acid esters or N-vinyl imidazoles are preferable.

The amount of the compound having a polymerizable unsaturated bond described above is
It is generally 0.1 to 10 wt%, preferably 1 to 5 wt% with respect to the inorganic fine particles.

The polymerization of the compound having a group capable of imparting triboelectricity and a polymerizable unsaturated bond on the surface of the inorganic fine particles can also be carried out by utilizing a radical polymerization reaction.

In order to bond a chain polymer having a triboelectric charging function to the surface of the inorganic fine particles by utilizing a radical polymerization reaction, it is preferable to previously treat the inorganic fine particles with a coupling agent having a vinyl group. As a result, a chain polymer having a charge control function is graft-polymerized to the vinyl group formed on the surface of the inorganic fine particles, so that the chain polymer can be firmly bonded to the surface of the inorganic fine particles. Becomes

Among the above coupling agents, examples of the silane coupling agent include vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane and the like.

Examples of titanate coupling agents include isopropyl dimethacryl isostearoyl titanate, isopropyl isostearoyl diacrylic titanate, and the like.

This radical polymerization reaction can be carried out by a general method using an ordinary single catalyst (radical reaction initiator) or a redox catalyst (redox initiator).

As a single-system radical reaction initiator, hydrogen peroxide,
_{K 2 S 2 O 8, (} NH 4) inorganic peroxides, such as ₂ S ₂ O _8, alkyl hydroperoxides, dialkyl peroxides, diacyl peroxides, organic peroxides such as esters, azo-bis-isobutyronitrile Examples thereof include azo compounds such as nitrile, dialkyl disulfides, and organic metal compounds containing heavy metals.

As the redox radical initiator, a combination of a peroxide such as persulfate, hydrogen peroxide or hydroperoxide and various reducing agents can be used. Specific examples of the combination include a combination of hydrogen peroxide and a ferrous salt, and a combination of benzoyl peroxide and dimethylaniline.

In the inorganic fine particles produced as described above, a polymer main chain having a side chain of a polymer having a triboelectrification function is graft-polymerized on the surface. These inorganic fine particles are
The toner for electrophotography of the present invention can be obtained by applying the toner onto the surface of the toner obtained by the production method shown below. Therefore, the toner does not peel off even if it is run for a long period of time, and excellent triboelectric chargeability is stably maintained for a long period of time. By using this toner, an image with little change in density can be provided.

Next, a method for producing a capsule toner will be described by taking as an example a method for producing a capsule toner composed of an outer shell of a polyurethane resin or a polyurea resin.

At least one resin selected from the group consisting of a polyurethane resin and a polyurethane resin around an oil droplet-shaped core substance containing a coloring material and a binder (and optionally magnetic particles) in an aqueous liquid. Methods for producing microcapsules by forming an outer shell are already known, and these known methods can also be used for producing the encapsulated toner of the present invention.

For example, an interfacial polymerization method can be mentioned as a method for producing microcapsules utilizing a polymerization reaction that can be used for producing a capsule toner. Further, as another example of the method for producing a microcapsule utilizing a polymerization reaction that can be used in the present invention,
An internal polymerization method and an external polymerization method can be mentioned.

Outer shell made of at least one resin selected from the group consisting of polyurea resin and polyurethane resin, diisocyanate, triisocyanate, tetraisocyanate, polyisocyanate such as polyisocyanate prepolymer, and diamine, triamine, tetraamine By reacting polyamines such as, prepolymers containing two or more amino groups, piperazine and its derivatives, polyols, etc. by an interfacial polymerization method in an aqueous solvent,
It is known that it can be easily formed as an outer shell of a microcapsule.

In addition, a composite wall made of a polyamide resin and at least one resin selected from the group consisting of polyurea resin and polyurethane preferable as the outer shell of the capsule toner, for example, a composite wall made of a polyurea resin and a polyamide resin, a polyurethane resin and a polyamide resin. The composite wall or the composite wall composed of polyurea resin, polyurethane resin and polyamide resin can be produced by the following method.

The composite wall made of polyurea resin and polyamide resin, the composite wall made of polyurethane resin and polyamide resin, for example, using polyisocyanate and acid chloride and polyamine and polyol, the pH of the emulsifying medium to be the reaction liquid
It can be prepared by an interfacial polymerization method which comprises adjustment and then heating. A composite wall composed of a polyurea resin and a polyamide resin can be prepared by using polyisocyanate, acid chloride and polyamine, adjusting the pH of the emulsifying medium serving as the reaction solution, and then heating. Details of the method for producing the composite wall made of the polyurea resin and the polyamide resin and the composite wall made of the polyurethane resin and the polyamide resin are described in JP-A-58-66948. The outer shell composed of such a composite wall is particularly suitable for forming an encapsulated toner containing magnetic particles in a core substance.

The monomers involved in the polymerization reaction for forming the outer shell resin differ depending on the resin forming the outer shell, but usually two or more kinds of monomers are used in combination. Examples of such a combination of monomers include a difunctional group compound containing a group selected from the group consisting of an isocyanate group, a thioisocyanate group, a bischloroformate group, an acid chloride group and a sulfonyl chloride group. A combination of at least one and at least one of compounds selected from the group consisting of water, polyhydric amines, polyhydric alcohols, polyhydric thiols, polyhydric amines and polycarboxylic acids can be mentioned.

The microcapsules with the outer shell formed are then washed with water.

In addition, it is preferable to carry out the outer shell forming reaction while performing the operation of removing the solvent of the outer shell material contained in the reaction system during the reaction of forming the outer shell.

On the other hand, a method for producing a non-encapsulated ordinary toner has already been known, and a known method can be used for producing the non-encapsulated toner of the present invention.

Examples of the binder (binding component) include homopolymers of styrene and its substitution products, styrene-based copolymers, and commonly used resin components.
These can be used alone or as a mixture.

As the coloring material, those which can be used for the above-mentioned capsule toner can be used.

The toner of the present invention may be provided with a commonly used charge control agent (or fluidizing agent) such as silica fine powder, alumina fine powder and titanium fine powder on its surface. Further, the toner may include a charge control agent normally contained in a toner such as nigrosine.

Next, examples and comparative examples of the present invention will be shown. In each example, "part" means "part by weight" unless otherwise specified.

[Example 1] 1-isopropyl-phenyl-2-phenylethane containing 50% by weight of polyisobutyl methacrylate (trade name: Acrybase, MM-2002-2: manufactured by Fujikura Kasei Co., Ltd.)
40 g of a solution in which Isopar · H (saturated saturated hydrocarbon mixture: manufactured by Exxon Chemical Co., Ltd.) was mixed at a weight ratio of 6: 5, and magnetite magnetic particles (trade name: EPT-1000: Toda Kogyo Co., Ltd.)
40 g) were mixed and dispersed in an automatic mortar to prepare a dispersion liquid (magnetic ink).

Separately, 20 g of ethyl acetate and 3 of xylylene diisocyanate
Mole and an addition compound of trimethylolpropane 1 mole (trade name: Takenate D-110N: Takeda Pharmaceutical Co., Ltd.) 9.9
A solution in which g was dissolved was prepared, and this solution was mixed with the above dispersion liquid (magnetic ink) to prepare an oily phase. However,
This oily phase mixed liquid (mixture of core substance and shell forming material)
Was prepared while adjusting the liquid temperature to 25 ° C. or lower.

Separately, 0.2 g of diethylenetriamine was added to 200 g of a 4% aqueous solution of methylcellulose (degree of substitution of methoxy group: 1.8, average molecular weight: 15000) to prepare an aqueous medium.
Cooled to 15 ° C.

The above oily phase mixed liquid was emulsified and dispersed in this aqueous medium to obtain an oil-in-water emulsion in which the average size of oil droplet particles in the emulsion was about 12 μm.

About 10 minutes after the preparation of the emulsion, 50 g of a 2.5 wt% aqueous solution of diethylenetriamine was gradually added dropwise, and the mixture was stirred in a constant temperature bath at 60 ° C. for 3 hours to complete the encapsulation.

The obtained microcapsule dispersion was allowed to stand naturally to allow the microcapsules to settle, the upper aqueous layer was discarded, washing water was added instead, and the mixture was allowed to stand with stirring. This washing operation 20
Repeated times to remove methylcellulose and the like adhering to the surface of the microcapsules. The washed microcapsule slurry was dried in an oven set at 80 ° C to obtain a capsule toner.

 Next, a graft polymerization treatment of titanium dioxide was performed.

30 g of titanium dioxide was dispersed in 70 g of water, 0.3 g of vinyltriethoxysilane was added, and water was evaporated at 100 ° C.
Then, this was redispersed in 70 g of water. 1 g of acrylonitrile, 0.1 g of potassium persulfate and sodium sulfite were added to the dispersion.
After adding 0.1 g and stirring at room temperature for 3 hours, water was evaporated at 100 ° C. and a polymer of acrylonitrile was graft-polymerized on the surface of titanium dioxide.

The obtained graft-polymerized titanium dioxide was mixed in an amount of 0.5 wt% with respect to the capsule toner.

This capsule toner was in a state where each capsule particle existed independently and showed a very smooth fluidity.

Next, using the obtained capsule toner, a positively chargeable electrostatic latent image formed by an ordinary one-component electrophotographic method was developed by a magnetic brush method, and then transferred to plain paper to obtain 150 kg / cm.
It settled at a pressure of ² .

The fixed visible image was clear and free from fog, and when observed with a magnifying glass, no fine toner scattering was observed. The visible image was rubbed with a finger 15 minutes after fixing, but no change was observed.

[Example 2] A capsule toner was manufactured in the same manner as in Example 1 except that the silica was graft-polymerized as follows in place of the titanium dioxide graft-polymerized.

Silica (Aerosil # 200, Nippon Aerosil Co., Ltd.)
30 g of water was dispersed in 70 g of water, and then Ce (NH ₄ ) ₃ (NO ₃ ) ₆ 0.1 g,
After adding 0.5 g of methyl methacrylate and 0.2 g of diethylaminoethyl methacrylate and stirring at room temperature for 3 hours,
Water was evaporated at 100 ° C., and the above copolymer was graft-polymerized on the surface of silica.

The resulting graft-polymerized silica was mixed in an amount of 0.5 wt% with respect to the capsule toner.

This capsule toner was in a state where each capsule particle existed independently and showed a very smooth fluidity.

Next, using the obtained capsule toner, a negative charging electrostatic latent image formed by a usual one-component electrophotographic method is developed by a magnetic brush method, and then transferred to plain paper to obtain 150 kg / cm.
It settled at a pressure of ² .

The fixed visible image was clear and free from fog, and when observed with a magnifying glass, no fine toner scattering was observed. The visible image was rubbed with a finger 15 minutes after fixing, but no change was observed.

Claims (6)

[Claims] 1. At least one kind of inorganic fine particles selected from the group consisting of metal oxides, carbonates and silicates, in which a chain polymer having a charge control function is bonded to the surface of toner particles by graft polymerization. A toner for electrophotography, characterized in that the toner is attached or contained. 2. The toner for electrophotography according to claim 1, wherein the inorganic fine particles are at least one fine powder selected from the group consisting of silica fine powder and titanium dioxide fine powder. 3. The toner for electrophotography according to claim 1, wherein the chain polymer is bonded to the surface of the inorganic fine particles treated with the coupling agent having a vinyl group by graft polymerization. 4. The toner for electrophotography according to claim 1, wherein the chain polymer is a polymer of a compound having an electron donating group. 5. The toner for electrophotography according to claim 1, wherein the chain polymer is a polymer of a compound having an electron-withdrawing group. 6. The electrophotographic toner according to claim 1, wherein the electrophotographic toner is a capsule toner having an outer shell made of at least one resin selected from the group consisting of polyurea resins and polyurethane resins. .