JPH09179336A - Production of toner and capsuled toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a toner having enough fixing property at low temp. which satisfies performances required for a toner such as offset resistance, developing property and storage property without requiring a special reaction device or complicated operation. SOLUTION: Polymer fine particles are produced by emulsion polymn. in the presence of an emulsifier containing a nonion surfactant. Then toner mother particles and the polymer fine particles are mixed in a water-based medium and heated to a temp. higher than the clouding point of the nonion surfactant, preferably higher than the glass transition temp. of the polymer fine particles to deposit the polymer fine particles on the surface of the toner mother particles. The polymer fine particles depositing on the mother particles are changed into a polymer coating layer. In order to change the polymer fine particles depositing on the mother particles into a film, such a process may be carried out that the polymer fine particles are made to absorb a solvent to form a film and then the solvent is removed, or that uniform mechanical impact force or compressive shearing force is added to the polymer fine particles depositing on the mother particles to form a uniform coating layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a toner for developing an electrostatic latent image in electrophotography and electrostatic printing.

[0002]

2. Description of the Related Art Today, copying machines or printers have
Along with the demand for high-quality images, there is a demand for high speed, power saving, and instant startability.

In order to satisfy these requirements, a toner which has a sufficient fixing property at a low temperature and which satisfies other required toner properties such as anti-offset property, developing property and storability is required.

The conventional toner manufacturing method is generally a method in which the toner is melted and kneaded with a thermoplastic resin, a coloring material and other additives, and the kneaded material is crushed and classified to obtain a toner. However, since the toner obtained by this method has a uniform composition, offset resistance, developability, storability,
It is difficult to make toner performance such as fluidity compatible with fixing performance. This is because, in order to realize sufficient fixability at low temperature, it is necessary to use a low Tg or low melting point resin as the thermoplastic resin, but if a low Tg or low melting point resin is used, the fixing roller will be fixed at the time of fixing. Part of the toner adheres, the toner is transferred to the non-image area, a so-called offset phenomenon occurs, and a part of the toner adheres to the carrier due to the mixing operation of the toner and the carrier in the developing machine to contaminate the carrier and develop. There is a problem in that the toner deteriorates in properties, and there is a problem that the toners agglomerate or fuse during storage due to the influence of the ambient temperature.

In recent years, a so-called capsule type toner in which the surface of toner base particles is covered with a polymer has been studied as an alternative means, and various methods have been proposed as a manufacturing method. Among them, a method of depositing the polymer fine particles on the surface of the toner base particles and then forming a film of the polymer fine particles to produce an encapsulated toner is generally used, and a step of attaching the polymer fine particles to the surface of the toner base particles, Any of the steps of forming a film of the polymer fine particles is an important step.

For example, Japanese Patent Laid-Open No. 57-45558 discloses a method of adding a water-soluble inorganic salt or changing the pH when adhering the polymer particles formed by emulsion polymerization to the surface of the toner base particles. Have been described. This method is effective for fine particles made of anionic surfactant, but is hardly effective for fine particles made of nonionic surfactant. Therefore, although a negatively chargeable toner can be produced, it is not suitable as a method for producing a positively chargeable toner and lacks versatility. Further, the formation of a film is not considered at all, and it cannot be said that the obtained toner particles are uniformly and sufficiently covered with the polymer resin.

Japanese Unexamined Patent Publication No. 1-257853 to 1-2
Japanese Patent No. 57856 discloses that when a fine particle formed by emulsion polymerization is attached to the surface of a toner mother particle obtained by suspension polymerization, a water-soluble polymerization initiator is added to a mixed liquid of the mother particle and the fine particle and reacted. That method is disclosed. According to this method, it is possible to uniformly coat the surface of the toner base particles with fine particles, but since the fine particles are merely attached in the form of particles and are not uniformly coated, the object of the present invention is achieved. It is not possible. In addition, Japanese Unexamined Patent Application Publication No.
186363, JP-A-4-188155,
JP-A-5-281782 discloses that fine particles formed by emulsion polymerization are dry-mixed on the surface of toner base particles,
A manufacturing method is disclosed in which fine particles are electrostatically attached to the surface of toner base particles and then fixed by impact force. Although this method has the advantage that it can be coated by a dry method, dried fine particles are difficult to redisperse into primary particles,
It is difficult to uniformly attach the fine particles to the surface of the toner base particles.

Japanese Unexamined Patent Publication No. 4-182660-4-1.
No. 82664 discloses that fine particles formed by emulsion polymerization are adhered to the surface of a toner base particle prepared by a kneading and pulverization method by a dry or wet method, and then spray dried by a solvent or a solvent. A manufacturing method of forming a film by performing steam treatment is disclosed. However, regarding the step of adhering the polymer fine particles, mere dry type or wet mixing treatment is described, and regarding the film forming step, although there is an advantage that continuous treatment can be performed, spraying or vaporization of a solvent The processing amount cannot be increased because the toners may be fused to each other by the processing. Also, since solvent vapor is used,
There is a drawback that it requires complicated equipment considering explosion proof and disaster prevention, and it is complicated and costly.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above drawbacks, and its purpose is to:
It is an object of the present invention to provide a method for producing a toner having sufficient fixability at low temperature and satisfying other toner required performances (offset resistance, developability, storability, etc.). Another object of the present invention is that both negatively chargeable toner and positively chargeable toner can be produced, and the adhesion and coating of fine particles to the toner base particles are sufficient and uniform, and the toner base particles do not agglomerate. The present invention provides a method for producing an electrophotographic toner, which has excellent adhesiveness and does not require a special reaction device or a complicated operation.

[0010]

The method for producing a toner according to the present invention is the method for producing a capsule toner in which a polymer coating layer is provided on the surface of toner base particles, wherein (1) an emulsifier containing at least a nonionic surfactant. In the presence of the step of forming polymer fine particles by emulsion polymerization, and (2) mixing the toner base particles and the polymer fine particles in an aqueous medium to a temperature not lower than the cloud point of the nonionic surfactant. Heating to attach the polymer particles to the surface of the toner base particles,
(3) a step of forming the polymer fine particles adhered to the toner base particles as a polymer coating layer.

The step of forming the polymer fine particles adhering to the surface of the toner base particles as the polymer coating layer comprises the step of absorbing the solvent into the polymer fine particles and removing the solvent to form the polymer coating layer. And a step of forming the coating layer by a compression shearing force or a mechanical impact force known as a mechanofusion system or a hybridization method.

Further, in the step of adhering the polymer fine particles on the surface of the toner base particles, it is preferable to heat the polymer fine particles to a temperature not lower than the glass transition temperature from the viewpoint of the adhesion strength.

In a preferred embodiment of the method for producing a toner of the present invention, the polymer fine particles used have an average particle size of 0.05.
To 3.0 μm, and the average particle diameter of the toner base particles is 0.1 to 15 μm.

When a solvent is used in the polymer coating layer forming step, the solvent is preferably absorbed in an amount of 0.01 to 50 parts by weight with respect to the toner particles to which the polymer fine particles are attached, and the boiling point of the solvent. Alternatively, the azeotropic point of the solvent and water is preferably 100 ° C. or lower.

Further, the encapsulated toner of the present invention is characterized by being obtained by the method for producing a toner according to claim 1 and being easily produced and having a uniform polymer coating layer.

In the method for producing a toner of the present invention, after polymer fine particles obtained by emulsion polymerization in the presence of an emulsifier containing a nonionic surfactant and toner base particles are mixed in an aqueous medium. By heating to a temperature above the cloud point of the nonionic surfactant, the dispersibility of the fine particles due to the nonionic surfactant sharply decreases, and the polymer fine particles that were uniformly dispersed in the aqueous medium are toner base particles. It is presumed that a uniform adhered layer of polymer fine particles is formed by adhering to the surface.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in detail.

The toner base particles applicable to the production method of the present invention and the production method thereof are not particularly limited, and particles produced by a kneading and pulverizing method in which a resin and a coloring material and other additives are kneaded and pulverized. It may well be particles produced by a so-called suspension polymerization method in which a resin monomer and a coloring material and other additives are both dispersed in an aqueous medium and polymerized to form toner base particles. Alternatively, after dispersing a mixed solution of a resin and a coloring material and other additives in an aqueous medium, the solvent is removed, particles produced by using an encapsulation reaction, and polymer particles are colored. The particles may be particles produced by aggregating and fusing together with other materials and other additives and having a toner particle size.

The toner base particles are composed of a resin and a coloring material and other additives, but in the present invention, any material that is generally used as a toner component can be applied. For example, as a resin that can be used, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, Hexyl acrylate (meth), (meth)
Lauryl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth)
(Meth) acrylates such as benzyl acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, phenyl (meth) acrylate, vinyl formate, acetic acid Vinyl, vinyl propionate, vinyl butyrate,
Fatty acid vinyl esters such as trimethyl vinyl acetate, vinyl caproate, vinyl caprylate and vinyl stearate, or vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, 2-ethylhexyl vinyl ether, phenyl vinyl ether, or methyl vinyl. Vinyl ketones such as ketones and phenyl vinyl ketones,
Styrene, chlorostyrene, hydroxystyrene, α-
Examples thereof include vinyl aromatic compounds such as methylstyrene. Further, one or a mixture of two or more of these resins may be used for copolymerization.

Alternatively, polyester, epoxy resin,
Polyamide, polyurethane, polyurea, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin and the like may be used alone or in combination of two or more.

Further, paraffin wax, microcrystalline wax, carnauba wax, or
Crystalline polyester, cis-1,4 polybutadiene,
It may be a crystalline resin such as cis and trans polydiene such as 1,2-trans polybutadiene, polyolefin such as polyethylene, polypropylene and polybutene, polyvinyl ester, polyvinyl ether, cellulose polymer and the like. Further, the non-crystalline resin and the crystalline resin may form a copolymer, or may be a simple mixture.

As these materials, those having a glass transition temperature or a melting point of about 20 to 60 ° C. are preferably used from the viewpoint of low temperature fixability. Specifically, (meth) acrylic acid esters, vinyl aromatic compounds, polyesters and the like are preferable.

The toner base particles may be particles made of these materials, and further may have an encapsulation structure obtained by interfacial polymerization and having a thin film formed on the surface in advance.

Examples of the coloring material include inorganic pigments such as carbon black, red iron oxide, dark blue and titanium oxide, azo pigments such as fast yellow, disazo yellow, pyrazolone red, chelate red, brilliant carmine and para brown, copper phthalocyanine, and Examples thereof include phthalocyanine pigments such as metal phthalocyanine, and condensed polycyclic pigments such as flavantron yellow, dibromoanthrone orange, perylene red, quinacridone red and dioxazine violet. Further, disperse dyes, oil-soluble dyes and the like can also be used.

Furthermore, as the magnetic one-component toner, all or part of the black coloring material can be replaced with magnetic powder. As the magnetic powder, magnetite, ferrite, a simple metal such as cobalt, iron, nickel, or an alloy thereof can be used. Further, a magnetic powder whose surface is treated with a coupling agent such as a silane coupling agent or a titanate coupling agent or an oil-soluble surfactant, or whose surface is coated with an acrylic resin, a styrene resin or an epoxy resin, Good.

In the method for producing the toner of the present invention, first,
The step of adhering the polymer particles to the surface of the toner base particles will be described.

After forming the polymer fine particles by emulsion polymerization in the presence of an emulsifier containing at least a nonionic surfactant, the toner base particles and the polymer fine particles are mixed in an aqueous medium.

In this mixing, the toner base particles or the toner base particle dispersion liquid may be mixed into the dispersion liquid as used in the emulsion polymerization of the polymer base particles, and the polymer base particles or the toner base particle dispersion liquid may be mixed. The polymer fine particles may be mixed as they are as a dispersion.

Thereafter, this mixed solution is heated to a temperature equal to or higher than the cloud point of the nonionic surfactant. When heat treatment is performed,
The polymer fine particles can be uniformly attached to the surface of the toner base particles. This is because the dispersion stability is rapidly reduced by heating the nonionic surfactant to a temperature above the cloud point, and the polymer fine particles that have been uniformly dispersed in the aqueous medium adhere to the surface of the toner base particles. It is estimated to be because. The polymer fine particles adhered to the surface of the toner base particles can be directly subjected to the next step as it is in order to uniformly coat the surface of the base particles in the polymer coating layer forming step that is subsequently performed.
From the viewpoint of obtaining a uniform film, it is preferable that the film is adhered to such a degree that it can be washed or the like in this adhesion step. Therefore, it is preferable to set the heating temperature of the mixed liquid to a temperature above the cloud point of the nonionic surfactant and above the Tg of the binder resin of the toner base particles. By setting the heating temperature to be equal to or higher than the binder resin Tg, the toner base particles and the polymer fine particles are partially fused at the adhering portions, and a stronger adhesion is achieved.

The average particle size of the polymer particles used here is from 0.05 μm to 3.0 μm, preferably 0.1 μm.
To 1.0 μm. Particles having a particle size of 0.05 μm or less are difficult to produce, and particles having a particle size of more than 3.0 μm make it difficult to coat the toner base particles uniformly and sufficiently.

A known emulsion polymerization method can be used as a method for producing the polymer fine particles. At this time, a nonionic surfactant is used as a part or all of the surfactant. By doing so, the dispersion stability of the produced polymer fine particles is drastically lowered at a temperature equal to or higher than the cloud point of the nonionic surfactant. When the toner base particles are present therein, the polymer fine particles gathered on the surface adhere to the surface of the toner base particles.

Examples of the nonionic surfactant include, for example,
Polyoxyethylene nonylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, and other polyoxyethylene alkyl allyl ethers or polyoxyethylene alkyl ethers, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, etc. And polyoxyethylene sorbitan esters, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol monooleate, and other polyoxyethylene fatty acid esters, and oxyethylene / oxypropylene block copolymers. Moreover, you may use together an anionic surfactant and a cationic surfactant with these nonionic surfactants in the range which does not impair the effect of this invention.

Examples of the polymerizable monomer used in emulsion polymerization for forming polymer fine particles include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic. Propyl acid, butyl (meth) acrylate, pentyl (meth) acrylate, (meth)
Hexyl acrylate, lauryl (meth) acrylate,
Cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate,
Hydroxyethyl (meth) acrylate, Hydroxypropyl (meth) acrylate, 2-Ethoxyethyl (meth) acrylate, Glycidyl (meth) acrylate, Phenyl (meth) acrylate, Trifluoroethyl (meth) acrylate, Acrylonitrile, (Meth) acrylic acid esters such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, trimethyl vinyl acetate, vinyl caproate, vinyl caprylate ,
Fatty acid vinyl esters such as vinyl stearate; or ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, hexyl vinyl ether,
2-Vinyl ethers such as ethylhexyl vinyl ether and phenyl vinyl ether; or vinyl ketones such as methyl vinyl ketone and phenyl vinyl ketone; vinyl aromatic compounds such as styrene, chlorostyrene, hydroxystyrene, α-methylstyrene; acryloyloxyethyltrimethylammonium chloride Acryloyloxyethyltriethylammonium chloride,
(Meth) acrylic acid ester ammonium salt monomers such as methacryloyloxyethyl trimethyl ammonium chloride, methacryloyl oxyethyl triethyl ammonium chloride, methacryloyl oxyethyl benzyl ammonium chloride; acrylamidotrimethylpropyl ammonium chloride, acrylamido triethylpropyl ammonium chloride, methacrylamidotrimethylpropyl ammonium (Meth) acrylamide ammonium salt monomers such as chloride and methacrylamidobenzylpropylammonium chloride; vinylbenzyl ammonium salt monomers such as vinylbenzylethylammonium chloride and vinylbenzyltrimethylammonium chloride; N-butylvinylpyridinini Vinylpyridinium salt monomers such as mubromide and N-cetylvinylpyridinium chloride; Fourth such vinyl imidazolium salt monomers such as N-vinyl-2-methylimidazolium chloride and N-vinyl-2,3-dimethylimidazolium chloride Examples thereof include vinyl monomers having a primary nitrogen, or those in which the halogen ion is replaced with another organic anion. These monomers may be used alone,
You may mix and use two or more monomers. Above all, it is preferable to use a polymer having a glass transition temperature of 40 to 80 ° C., specifically, (meth) acrylic acid esters, (meth) acrylic acid ester-based ammonium salt monomers, (meth). Acrylamide ammonium salt monomers are preferred.

In the method for producing a toner of the present invention, there is no particular limitation on the step of forming the polymer fine particles adhering to the surface of the toner base material particles into the polymer coating layer (hereinafter, appropriately referred to as a film forming step). For example, when a glass transition temperature or a melting point of 20 to 40 ° C. is used as the matrix particle material and a glass transition temperature of 40 to 80 ° C. is used as the polymer fine particles, the polymer fine particles are heated and melted. The method of forming a uniform film is not preferable because even the toner base material particles may be melted and deformed by heating. For this reason,
A method of forming a uniform polymer coating layer by absorbing the solvent into the polymer fine particles without heating and then removing the solvent to form the polymer coating layer, a so-called mechanofusion system or a hybridization method. A method of forming a polymer coating layer by using compression shearing force or mechanical impact force is preferably used.

Here, the film forming process using a solvent will be described. This step has a step of absorbing a solvent into the polymer fine particles and a step of removing the solvent to form a polymer coating layer.

The solvent used here may be any solvent as long as it dissolves or swells the polymer fine particles, but the boiling point of the solvent or the azeotropic point of the solvent and water is used. Those having a boiling point lower than that of water are preferably used from the viewpoint of easy removal of the solvent. Specifically, for example, ketone solvents such as acetone, methyl ethyl ketone, and methyl isopropyl ketone, ethyl formate,
Ester solvents such as propyl formate, isobutyl formate, methyl acetate, ethyl acetate, isopropyl acetate, halogenated hydrocarbon solvents such as chloroform, dichloroethane, trichloroethane, dichloroethylene, trichloroethylene, hydrocarbon solvents such as benzene and toluene, diethyl ether And ether solvents such as dipropyl ether, diisopropyl ether, dioxane, tetrahydrofuran, tetrahydropyran, and dimethoxyethane. These solvents may be used alone or as a mixture of two or more as long as there is no problem in compatibility. Among them, acetone (boiling point: 5
6.5 ° C.), methyl ethyl ketone (boiling point: 79.6)
C.), ethyl acetate (boiling point: 77.15 ° C.), tetrahydrofuran (boiling point: 64-65 ° C.) and the like are preferable.

The amount of the solvent to be absorbed varies depending on the solid content concentration of the toner suspension, the hydrophilicity of the solvent used or the amount of the polymer fine particles adhered, but the toner concentration is 20%. A preferable result is obtained in the range of 0.01 to 10 parts by weight based on the total amount of the toner particles including the polymer particles. The method of absorbing the solvent in the polymer fine particles includes (1) a method of directly dropping the solvent into the toner base particle dispersion liquid to which the polymer fine particles are attached, and (2) dissolving or suspending the solvent in water or alcohol. A method of dropping into the dispersion liquid, (3) the toner base particle dispersion liquid having the polymer fine particles adhered thereto is once drained, made into a cake state or a slurry state, and then redispersed in an aqueous solution or suspension of a solvent. Method, etc.

When a solvent is added to the toner base particles to which the polymer fine particles are attached, the polymer fine particles attached to the toner base particles absorb the solvent and soften to form a uniform coating layer state from the shape of the fine particles. Everywhere

After forming a uniform polymer coating layer, the absorbed solvent is removed by a known solvent removal method such as distillation, extraction operation, and drying operation such as spray drying. At this time, in order to prevent the fusion and aggregation of the toners, inorganic fine particles such as calcium carbonate and calcium phosphate, and water-soluble polymers such as polyvinyl alcohol, methyl cellulose, hydroxypropyl methyl cellulose and carboxymethyl cellulose may be added.

According to the method using this solvent, when it is desired to impart specific performance to the toner, for example, to impart only the charge or to impart only the fluidity, the kind and amount of the solvent to be absorbed By further controlling the temperature, time, etc., the toner base particles are not completely covered,
It is also possible to form a film partially.

Further, as another step of forming the polymer fine particles adhering to the surfaces of the toner base particles as a polymer coating layer, the coating layer is formed by a compression shearing force or a mechanical impact force known as a mechanofusion system or a hybridization method. The method of forming may be mentioned.

This method is a method of applying a mechanical impact force or a compressive shearing force to the polymer fine particles adhered to the surface of the toner base particles to form a uniform layer. The hybridization device manufactured by Nara Machine Co., Ltd., Hosokawa Micron Co., Ltd. This can be easily carried out by using a Mechanofusion system device manufactured by K.K. According to this method, although a dedicated device is required, the coating layer can be formed without using an auxiliary agent such as a solvent, and thus it is particularly useful in small-lot production.

By adhering the polymer fine particles to the toner base particles by these methods and forming a uniform coating layer of the polymer on the surface of the base particles, the fluidity of the toner is higher than that of the toner base particles before the formation of the coating layer. However, in order to improve the fluidity or chargeability of the toner, silicon oxide,
External additives such as aluminum oxide, titanium oxide and carbon black may be added. The external additive may be added by drying the encapsulated toner and then adhering the external additive to the toner surface using a mixer such as a V blender or a Henschel mixer, or adding the external additive to water or water / alcohol. After dispersing in an aqueous solvent, it is added to a capsule toner in a slurry state and dried to attach an external additive to the toner surface.

[0044]

The present invention will be described in more detail with reference to specific examples, but the present invention is not limited to these examples.

Example 1 Preparation of toner base particles Styrene-n-butyl acrylate polymer (SBM10)
0: Sanyo Chemical Co., Ltd. [Tg = 42 ° C., Mw = 1480
0]) 88 parts, carbon black (Regal-33
0: 6 parts by Cabot Co., Ltd.) and 6 parts of low molecular weight polypropylene (P-200: by Mitsui Petrochemical Co., Ltd.) were dry-mixed, then kneaded, pulverized and classified to obtain an average particle size of 8 μm.
Toner base particles of

3. Preparation of polymer fine particles In a 1 liter separable flask equipped with a cooling tube and a nitrogen introducing tube, 500 g of pure water and a nonionic surfactant (Emulgen 920: Kao Corporation [cloud point 82 ° C.]) 4. 0 g was added, and the mixture was stirred at 200 rpm with a stirrer (three-one motor: manufactured by Shinto Kagaku Co., Ltd.) equipped with a propeller-type stirring blade,
The surfactant was dissolved. After the system was replaced with nitrogen, the following monomer composition was added and emulsified.

Styrene monomer (manufactured by Mitsubishi Gas Chemical Co., Inc.): 100 g n-butyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.): 85 g methacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd.): 5 g lauryl mercaptan (manufactured by Wako Pure Chemical Industries, Ltd.) : 0.4 g After heating the reaction solution to 65 ° C., 100 g of a 2 wt% potassium persulfate aqueous solution was added, and the polymerization reaction was carried out as it was at 65 ° C. for 20 hours to give an average particle size of 0.6 μm and a weight average molecular weight. Polymer fine particles of 1.5 × 10 ⁵ (Tg = 55 ° C.) were obtained.

Preparation of Encapsulated Toner and Toner Composition 50 g of the toner base particles obtained as described above was added to 200 g of the polymer fine particle suspension, and a stirrer equipped with a propeller type stirring blade (three one motor: new (Made by Togaku Kagaku)
At 200 rpm. Warm up slowly to 82 ° C. When the liquid temperature reached 81 ° C, the liquid that had been smooth until then turned into a rough feeling. When the hot water bath was removed and stirring was continued while cooling, the liquid changed to a smooth state again. The toner and extra polymer particles were separated by centrifugation, and the obtained toner was further washed with pure water, redispersion with an ultrasonic cleaner, and vacuum filtration three times. When a part of the toner was taken out and observed with a scanning electron microscope (SEM), it was confirmed that the polymer fine particles were uniformly attached to the surface of the toner base particles.

Ion-exchanged water was added to the toner base particles having polymer particles adhered to the surface thus obtained to prepare a suspension having a solid content concentration of 20%. Next, 200 g of the prepared suspension was rotated at 200 rpm with a stirrer (three-one motor: manufactured by Shinto Kagaku Co., Ltd.) equipped with a propeller-type stirring blade.
Stir in minutes. 5g of ethyl acetate was added to 100g of pure water.
The liquid dissolved in was dropped over 1 hour to be absorbed by the toner. After stirring for 3 hours as it was, ethyl acetate was removed at 50 ° C. When a part of the toner was taken out and observed by SEM, it was confirmed that the polymer fine particles that were uniformly attached to the surfaces of the toner base particles formed a uniform film and covered the toner base particles.

The obtained encapsulated toner was filtered and washed with 1 liter of ion-exchanged water under reduced pressure. The cake of the obtained toner was placed in a stainless steel vat and dried at 60 ° C. for 20 hours with a dryer (manufactured by Yamato Scientific Co., Ltd.).

To 100 parts of the obtained encapsulated toner, 0.1 part of carbon black (REGAL330R: manufactured by Cabot Corporation) was added and mixed well to obtain a toner composition.

Example 1 Preparation of toner base particles 2 g of calcium carbonate (luminous: manufactured by Maruo Calcium Co.)
Was added to 250 g of ion-exchanged water and treated with an ultrasonic cleaner for 5 minutes to obtain an aqueous dispersion of calcium carbonate. On the other hand, the polyester resin (Tg = 66 ° C. MW = 108)
00 Mn = 5300: manufactured by Kao) 25 g, cyan pigment (phthalocyanine blue 4933M: manufactured by Dainichiseika)
1.5 g was dissolved in 95 g ethyl acetate solution and dispersed for 6 hours by a sand mill (tabletop sand mill: manufactured by Kansai Paint Co., Ltd.). (This liquid is referred to as liquid B) Next, the liquid A cooled to 10 ° C. was added to an emulsifier (ULTRA).
-TURRAX T50: manufactured by IKA) is installed, and
Stirred at 00 rpm. Solution B was slowly added to this. The rotation speed was increased to 10,000 rotations / minute to emulsify. Thus, an O / W emulsion in which the average particle size of the oil droplet particles in the emulsion was about 8 μm was obtained.

Next, the emulsifier was replaced with a stirrer equipped with a propeller type stirring blade (Three One Motor: manufactured by Shinto Kagaku Co., Ltd.), and ethyl acetate in the emulsion was distilled by distillation while stirring at 400 rpm. I removed it. After the distillation operation was completed, it was poured into 2 liters of ion-exchanged water, sufficiently stirred, and allowed to stand. After the toner particles settled, the supernatant was removed. 0.5% of the toner slurry thus obtained
Was added to the above hydrochloric acid to decompose and remove calcium carbonate, which was thoroughly washed with water and then filtered to obtain toner base particles. Ion-exchanged water was added to the toner base particles to prepare a suspension having a solid content concentration of 40%.

Preparation of Polymer Fine Particles In a 1 liter separable flask equipped with a cooling pipe and a nitrogen introducing pipe, 500 g of pure water and a nonionic surfactant (Emulgen B-66: manufactured by Kao Corporation [cloud point 66.8 ° C.] ]) 4.0
g was added, and the mixture was stirred at 200 rpm with a stirrer equipped with a propeller-type stirring blade (Three One Motor: manufactured by Shinto Scientific Co., Ltd.) to dissolve the surfactant. After the system was replaced with nitrogen, the following monomer composition was added and emulsified.

Styrene monomer (manufactured by Mitsubishi Gas Chemical Co., Inc.): 160 g n-butyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.): 40 g Lauryl mercaptan (manufactured by Wako Pure Chemical Industries, Ltd.): 0.4 g The reaction solution was heated to 62 ° C. Then, 100 g of a 2 wt% potassium persulfate aqueous solution was added, and the polymerization reaction was carried out as it was at 62 ° C. for 24 hours to obtain polymer fine particles having an average particle diameter of 0.8 μm and a weight average molecular weight of 1.7 × 10 ⁵ (Tg = 57. C) was obtained. After the reaction was completed, the obtained polymer fine particles were washed by centrifugation. Ion-exchanged water was added to the polymer particles to prepare a suspension having a solid content concentration of 40%.

Preparation of Encapsulated Toner and Toner Composition To 125 g of the prepared toner base particle suspension (corresponding to 50 g of toner base particle), a polymer fine particle suspension 200 was prepared.
g was added and the mixture was stirred at 200 rpm with a stirrer (three-one motor: manufactured by Shinto Kagaku Co., Ltd.) equipped with a propeller-type stirring blade. Warm up slowly to 70 ° C. Liquid temperature is 67 ℃
At that point, the liquid that had been smooth until then changed to a rough texture. When the hot water bath was removed and stirring was continued while cooling, the liquid changed to a smooth state again.
The toner and excess polymer particles were separated by centrifugation. When a part of the toner was taken out and observed with a scanning electron microscope (SEM), it was confirmed that the polymer fine particles were uniformly attached to the surface of the toner base particles.

Ion-exchanged water was added to the toner base particles having polymer particles adhered to the surface thus obtained to prepare a suspension having a solid content concentration of 20%. 250 g of the prepared suspension was stirred at 200 rpm with a stirrer (Three One Motor: manufactured by Shinto Kagaku Co., Ltd.) equipped with a propeller-type stirring blade. To this, 10 g of ethyl acetate was added dropwise over 1 hour to be absorbed by the toner. After stirring for 3 hours as it was, ethyl acetate was removed at 50 ° C. When a part of the toner was taken out and observed by SEM, it was confirmed that the polymer fine particles that were uniformly attached to the surface of the toner base particles formed a uniform film and covered the toner base particles.

The obtained encapsulated toner was filtered and washed with 1 liter of ion-exchanged water under reduced pressure. The cake of the obtained toner was placed in a stainless steel vat and dried at 60 ° C. for 20 hours with a dryer (manufactured by Yamato Scientific Co., Ltd.).

To 100 parts of the obtained encapsulated toner, 0.1 part of silica (Aerosil R972: manufactured by Nippon Aerosil Co., Ltd.) was added and mixed well to obtain a toner composition.

Comparative Example 1 The same treatment as in Example 1 was carried out except that the toner base particles were stirred at room temperature instead of being added to the polymer fine particle suspension and stirred at 82 ° C. When a part of the toner was taken out and observed with a scanning electron microscope (SEM), almost no polymer fine particles adhered to the surface of the toner base particles.

Further thereafter, the same treatment as in Example 1 was carried out to obtain a comparative toner composition. Comparative Example 1 A comparative toner composition is obtained by performing the same treatment as in Example 1 except that the step of adding a solvent to the toner base particles to which the polymer fine particles obtained in Example 1 is attached is not performed. It was When a part of the toner particles was taken out and observed with a scanning electron microscope (SEM), the polymer particles adhered to the surface of the toner base particles, but they were independent and formed a uniform film. Was not there.

Comparative Example 3 The same procedure as in Example 2 was carried out except that the toner base particles were stirred at room temperature instead of being added to the polymer fine particle suspension and stirred at 70 ° C. When a part of the toner was taken out and observed with a scanning electron microscope (SEM), almost no polymer fine particles adhered to the surface of the toner base particles.

Further thereafter, the same treatment as in Example 1 was carried out to obtain a comparative toner composition. (Comparative Example 4) A comparative toner composition was obtained by performing exactly the same treatment as in Example 2 except that the step of adding a solvent to the toner base particles to which the polymer fine particles obtained in Example 2 were not added was performed. Obtained. When a part of the toner particles was taken out and observed with a scanning electron microscope (SEM), the polymer particles adhered to the surface of the toner base particles, but they were independent and formed a uniform film. Was not there.

Performance Evaluation of Toner Composition Using the toner compositions obtained in the above-mentioned Examples and Comparative Examples, a copying machine "Vivace-" manufactured by Fuji Xerox Co., Ltd. was used as an evaluation machine.
550 is used to set the fixing set temperature to the normal fixing set temperature 19
Image formation was performed at 174 ° C., which is 20 ° C. lower than 4 ° C.

The characteristics of the toner and the characteristics of the formed image were evaluated by the following methods. The results are shown in Table 1 below. (Storability) 1.0 g of toner was placed in a beaker and stored in an oven at 45 ° C. for 24 hours, and then the opening was 100 μm.
When the amount of the toner remaining on the sieve was less than 5% by weight based on the total amount of the toner, it was evaluated as ◯, from 5 to 25% by weight was evaluated as Δ, and when it exceeded 25% by weight, it was evaluated as x. (Fixability) The fixed image was rubbed with an eraser and the degree of image removal was visually evaluated. The case where the image could not be removed by rubbing with the eraser was evaluated as ○, and the case where the image of the rubbed portion was removed was evaluated as ×. (Offset) The presence / absence of toner transfer to the non-image area is visually determined, and the toner transfer in the non-image area is indicated by ○,
What was not seen was evaluated as x. (Developability) Take 1,000 unfixed copies and
When the image density of the first sheet was compared with the image density of the first sheet, it was evaluated as ◯ when it was visually determined not to decrease, and as x when it was determined to be decreased.

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[Table 1]

As is clear from Table 1, the toner composition obtained by the production method of the present invention has excellent toner storability.
It was excellent in all evaluations of fixing property, offset property, and developability at low temperature. On the other hand, although the toner compositions of Comparative Examples obtained by the conventional method have no problem in fixability, they do not have a uniform coating layer on the surface of the toner base particles, and therefore have problems in offset resistance and storage stability. In particular, it was confirmed that Comparative Examples 2 and 4 in which the polymer coating layer forming step with a solvent was not performed were inferior in developability at low temperature.

[0068]

According to the production method of the present invention, a uniform polymer coating layer is provided, and sufficient fixing property at low temperature and other required properties of toner such as offset resistance, developability and storability are obtained. A toner satisfying both requirements was obtained without requiring a special reaction device or complicated operation.

Claims (9)

[Claims] 1. A method for producing a capsule toner having a polymer coating layer on the surface of toner base particles, wherein (1) polymer fine particles are formed by emulsion polymerization in the presence of an emulsifier containing at least a nonionic surfactant. And (2) mixing the toner base particles and the polymer fine particles in an aqueous medium, and heating the mixture to a temperature not lower than the cloud point of the nonionic surfactant so that the polymer is formed on the surface of the toner base particles. A method for producing a toner, comprising: a step of adhering fine particles; and (3) a step of forming the polymer fine particles adhering to the toner base particles into a polymer coating layer. 2. The step of forming the polymer fine particles adhering to the surface of the toner base particles as a polymer coating layer, the step of absorbing the solvent in the polymer fine particles and removing the solvent to form the polymer coating layer. The method for producing a toner according to claim 1, further comprising: 3. The step of forming the polymer fine particles adhering to the surface of the toner base particles as a polymer coating layer is a step of forming the coating layer using mechanical impact force or compression shearing force. The method for producing a toner according to claim 1. 4. The method for producing a toner according to claim 1, wherein in the step of adhering the polymer fine particles to the surface of the toner base particles, heating is performed to a temperature not lower than the glass transition temperature of the polymer fine particles. 5. The average particle size of the polymer fine particles is 0.
The method for producing a toner according to claim 1, wherein the toner has a thickness of 05 to 3.0 μm. 6. The average particle diameter of the toner base particles is
The method for producing a toner according to claim 1, wherein the toner has a thickness of 0.1 to 15 μm. 7. The method for producing a toner according to claim 2, wherein 0.01 to 50 parts by weight of the solvent is absorbed in the toner particles. 8. The method for producing a toner according to claim 2, wherein the boiling point of the solvent or the azeotropic point of the solvent and water is 100 ° C. or lower. 9. An encapsulated toner, which is a toner obtained by the method for producing a toner according to claim 1.