JP2000305311A - Electrophotographic toner, developer, and image forming method using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic toner, a developer and an image forming method having excellent suitability to cleaning while retaining good developing performance and transferability in an electrophotographic toner containing toner particles having a nearly spherical particle shape and having a narrow particle size distribution in spite of having a small volume average particle diameter. SOLUTION: The electrophotographic toner contains toner particles containing a bonding resin as an essential component and having 3-10 μm volume average particle diameter, a volume average particle size distribution(GSD) of <=1.25 and a shape factor (ML' 2/A) of 105-130 and contains fine particles of a low molecular weight fluorine-containing compound selected from polytetrafluoroethylene, a tetrafluoroethylene-containing copolymer, a fluoro- polyether and a perfluoroalkyl-containing compound. The fine particles have 0.01-0.5 μm average dispersion particle diameter and 5.5×104-1.0×108 P melt viscosity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developing toner used for developing an electrostatic latent image in electrophotography and electrostatic recording, and an image forming method using the toner.

[0002]

2. Description of the Related Art Methods for visualizing image information via an electrostatic image, such as electrophotography, are currently used in various fields.
In electrophotography, an electrostatic image is formed on a photoconductor by a charging and exposing process, an electrostatic latent image is developed with a developer containing a toner, and the image is visualized through a transfer and fixing process. The developer used here includes a two-component developer composed of a toner and a carrier, and a one-component developer that uses a magnetic toner or a non-magnetic toner alone. A kneading and pulverizing method is used in which the mixture is melt-kneaded with a release agent such as a charge controlling agent and wax, cooled, finely pulverized, and further classified. If necessary, inorganic or organic fine particles for improving the fluidity and cleaning properties may be added to the surface of the toner particles. In the kneading and pulverizing method generally used, the toner shape and the surface structure of the toner are indefinite, and vary delicately according to the pulverizability of the materials used and the conditions of the pulverization process. Control is difficult. Particularly, in the case of a material having high pulverizability, the generation of fine powder or a change in the shape of the toner often occurs due to mechanical force in a developing machine as a toner.

[0003] Due to these effects, in a two-component developer, charge deterioration of the developer is accelerated due to sticking of fine powder to a carrier surface, and in a one-component developer, toner is scattered due to expansion of a particle size distribution. Deterioration of image quality is likely to occur due to a decrease in developability due to a change in toner shape.
In addition, when a toner is formed by internally adding a release agent such as a wax, exposure of the release agent to the surface is often affected by combination with a thermoplastic resin. In particular, in the case of a combination of a resin having elasticity imparted by a high molecular weight component and being hardly pulverized and a brittle wax such as polyethylene, the wax is often exposed on the toner surface. Although these are advantageous for the releasability at the time of fixing and cleaning of the untransferred toner from the photoreceptor, the contamination of the developing roll, the photoreceptor, and the carrier due to the wax on the toner surface layer being easily transferred by mechanical force. More likely to occur, leading to lower reliability.

Further, since the shape of the toner is indefinite, the fluidity is not sufficient even with the addition of a fluidity aid, and the fluidity aid is buried in the toner by mechanical force during use. In addition, transferability and cleaning performance deteriorate. Further, if the toner collected by the cleaning is returned to the developing machine and used again, the image quality is further likely to be reduced. If the flow aid is further increased in order to prevent these, black spots will be generated on the photoreceptor and the aid particles will be scattered. Therefore, in recent years, studies have been actively conducted on a wet toner production method as a means that enables intentional control of the toner shape and surface structure.For example, JP-A-63-282752 and JP-A-6-250439 disclose an emulsion polymerization aggregation method. A method for producing a toner has been proposed. These generally produce a resin dispersion by emulsion polymerization or the like, and on the other hand produce a colorant dispersion in which a colorant is dispersed in a solvent, mix and form an aggregate corresponding to the toner particle size,
A manufacturing method has been proposed in which a toner is fused and united by heating.

In the emulsion polymerization aggregation method, it is easy to reduce the diameter of the toner while maintaining a narrow particle size distribution as compared with the kneading and pulverizing method. This has the advantage that the degree of morphology and sphericity can be controlled. Here, by reducing the particle size of the toner particles, high image quality such as improvement in resolution and granularity can be achieved.On the other hand, the charge amount of a single toner generally decreases with the reduction in the toner particle size. It is a well-known fact that problems such as a decrease in development latitude, a decrease in transferability, and a decrease in cleanability due to easiness and easiness of generation of toner dirt occur. Amorphous toner particles obtained by a conventional kneading and pulverizing method are used for charging frictional contact with a charging member, for example, a sleeve in a one-component developing method, or contact frictional charging with carrier particles in a so-called two-component developing method. In this case, it is considered that the actual surface charge density distribution of the toner particles is not uniform but rather unevenly localized because the convex portions of the toner particles are selectively contacted with the charging member. I have. Further, since the charge amount of one toner decreases as the toner diameter decreases, such a non-uniformly localized toner in a charged state results in
A high developing electric field (an electric field required to peel the toner from the sleeve and the carrier) and a high transfer electric field (an electric field necessary to peel the toner from the photoconductor) are required.

[0006] In the case of spherical toner, since there is no concave portion on the toner surface at least, the chargeable area of the toner is larger than that of the irregular toner. Also, because the charge density distribution on the toner surface has become uniform, or because of the effect of reducing the contact area, the adhesive force tends to be smaller than that of the irregular toner, which is considered to be effective in improving transferability. . From these viewpoints, there is a great expectation for improvement of the above-mentioned problems by using the emulsion polymerization aggregation method toner. However, studies by the present inventors have revealed that, on the other hand, a toner using a wet process such as an emulsion polymerization aggregation method has a worse cleaning property than a toner of an irregular shape by a kneading and pulverizing method. In particular, when a toner having a small particle size and high sphericity is used, it is difficult to perform sufficient cleaning by the conventional cleaning method. Further, even when a condition is set in the wet toner manufacturing method in which an amorphous shape is set as the center shape, the shape on the small particle size side is often close to a spherical shape, so that the small particle size toner is selectively cleaned poorly. It may be. Here, the cleaning property refers to not only the removability of toner components remaining on the surface of the electrostatic image carrier including the organic photoreceptor, but also a member that comes into contact with the electrostatic image carrier, specifically, It also shows the removability of toner components remaining on the contact charging roll, intermediate transfer belt, intermediate transfer drum, and the like.

As a method of compensating for the poor cleaning property, a mechanism for electrically collecting the remaining toner by an electrostatic brush may be considered. However, the collecting mechanism becomes complicated and has a large capacity. Inability to meet energy conservation requirements. As a conventional technique, it is known that it is effective to use spherical resin fine particles, for example, polymethyl methacrylate particles obtained by soap-free polymerization as a cleaning aid, but these techniques are applied to an emulsion polymerization aggregation method toner. In order to exert the effect, a very large amount of addition is required, and the spherical resin particles themselves are detached from the toner and pass through the cleaning portion, so that there is a problem that an image trouble due to an exposure trouble is easily caused.

Japanese Patent Application Laid-Open No. Sho 60-166957 discloses a one-component toner containing a binder resin and a magnetic powder by adding a fluororesin powder to the inside and / or the surface of the toner particles. To prevent the photoreceptor from adhering to the photoreceptor surface and damaging the photoreceptor.
Japanese Patent Application Laid-Open No. Sho 60-79361 describes that polyvinylidene fluoride resin powder is fixed on the surface of toner particles for the same purpose. Also, Japanese Patent Application Laid-Open No. 57-844
No. 60 discloses that a toner, such as fluororesin, polyethylene, polypropylene, polyamide, molybdenum disulfide, etc., is added to a toner powder to prevent damage to a photoconductor caused by removing toner particles by a brush or a blade in a cleaning process. Is described. The toner particles disclosed in these publications are all toner particles obtained by a pulverization method, having an irregular particle shape and a wide range of particle diameters. The added fluororesin and the like are all high molecular weight fluororesins. However, even if the method of adding such a high molecular weight fluororesin powder is produced by a wet process, the shape is close to a sphere, and even if applied to toner particles having a small volume average particle size or a narrow particle size distribution, cleaning is performed. It is not possible to improve sex. On the other hand, JP-A-4-102860
Japanese Patent Application Laid-Open Publication No. H11-157, describes that the cleaning property is improved by adding polytetrafluoroethylene fine particles having a molecular weight of 500 to 5,000 (particle diameter: 0.5 to 5 μm) to toner particles containing a binder resin and a colorant as main components. ing. However, the toner particles described in this publication are also produced by a pulverization method, and the molecular weight of the polytetrafluoroethylene resin is as low as 500 to 5,000. The cleaning property is not remarkably improved even if it is added to the toner particles produced by the above method.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object the purpose of having a particle shape relatively close to a sphere and a narrow particle size distribution even if the volume average particle size is small.
For example, in an electrophotographic toner including toner particles produced by a wet manufacturing method, an electrophotographic toner having excellent cleaning suitability while maintaining good development and transfer performance, and a developer including the toner are provided. Another object of the present invention is to provide an image forming method using the toner.

[0010]

The above objects of the present invention can be attained by providing the following electrophotographic toner, developer and image forming method. 1. (1) A binder resin is contained as an essential component, the volume average particle diameter of the toner particles is 3 to 10 μm, the volume average particle size distribution (GSD) is 1.25 or less, and the shape factor (ML ^ 2 / A) of the toner particles is ) Is a toner for electrophotography containing toner particles in the range of 105 to 130, wherein the toner has an average dispersed particle diameter of 0.01 to 0.5 μm and a melt viscosity of 5.
A low molecular weight fluorine-based compound selected from the group consisting of polytetrafluoroethylene, a copolymer containing tetrafluoroethylene, a fluoropolyether and a compound containing a perfluoroalkyl group in the range of 5 × 10 ⁴ to 1.0 × 10 ⁸ poise; An electrophotographic toner comprising at least one compound fine particle. When an image is formed using the toner, excellent cleaning characteristics can be obtained while maintaining development and transfer performance, and the obtained image is excellent in image quality and does not cause secondary trouble.

In the toner, the volume average particle size distribution (GSD) of the toner particles is preferably 1.25 or less, more preferably 1.23 or less. As the low molecular weight fluorine-based compound, a tetrafluoroethylene-containing polymer, in particular, polytetrafluoroethylene is preferable. Further, the fine particles of the low-molecular-weight fluorine-based compound may be those simply mixed with toner particles, those that are strongly adhered to the toner surface by applying a shearing force when mixing the toner particles and the fine particles, In the case where the fine particles are produced by an agglomeration method, a dispersion of the fine particles may be added in the aggregating step, and the fine particles may be present in any state in which the fine particles are partially embedded in the surface of the toner particles.

(2) In the electrophotographic toner of the above (1), the relationship between the particle size distribution of the toner particles and the shape factor (ML ^ 2 / A) preferably satisfies the following equation (1). Formula (1) M ₅₀ (b)> M ₅₀ (a)> M ₅₀ (c) Here, M ₅₀ (b) is the particle size distribution of the toner particles.
The cumulative number% of the number of particles counted from the larger particle size side is 16
%, The average shape factor of particles having a particle number of ₅₀ % or less, M ₅₀ (a) indicates the average shape factor of particles having a cumulative number% in the range of 42 to 58%, and M ₅₀ (c) indicates the cumulative number%. The figure shows the average shape factor of particles of 84% or more. (3) In the electrophotographic toner according to the above (1) or (2), the toner particles are obtained by mixing a resin particle dispersion in which resin particles of at least 1 μm or less are dispersed with a colorant dispersion in which a colorant is dispersed. After the resin particles and the colorant are agglomerated to the particle size of the toner, it is preferably obtained by a method of heating the resin to a temperature equal to or higher than the glass transition point and fusing and aggregating the aggregates to form particles. (4) The toner for electrophotography according to any one of (1) to (3), wherein the toner particles are a resin particle dispersion in which resin particles of at least 1 μm or less are dispersed and a coloring agent in which a colorant is dispersed. After the resin dispersion and the colorant are agglomerated (formation of mother aggregated particles), a particle dispersion of 1 μm or less is additionally mixed into the dispersion of the mother aggregated particles at least once. After adhering the particles to the particle surface, the particles are heated to a temperature higher than the glass transition point of the resin contained in the mother aggregated particles and / or the additional particles to be fused and coalesced (hereinafter, this method is referred to as “matrix aggregated particle formation”). Method).) It is preferably toner particles.

2. Any one of the above (1) to (4)
A two-component developer comprising the electrophotographic toner and a carrier according to item 1. 3. Forming an electrostatic latent image on the electrostatic image carrier, developing the electrostatic latent image with a developer, transferring the developed image to a transfer medium, and / or electrostatic image carrier and / or A cleaning step of removing toner remaining on the member adjacent to the electrostatic image carrier. An image forming method, comprising using a developer containing the toner described in (1). Here, the transfer medium is not limited to the final image recording medium,
Also includes an intermediate transfer member. The member adjacent to the electrostatic image carrier means a charging member or an intermediate transfer member. In particular, when the electrophotographic toner of the present invention is used in an image forming method including a step of cleaning residual toner by pressing a rubber blade, excellent cleaning properties are exhibited. In the image forming method of the present invention, the above-described 1. Can be achieved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. As a result of intensive studies, the present inventors have found that in an electrophotographic toner containing toner particles having a specific particle size, particle size distribution, and shape factor, the contact interface between the toner and the electrostatic image carrier, the toner and the intermediate transfer The inventors have found that the above problems can be solved by interposing specific fine particles at the contact interface between the body and the contact interface between the toner and the charging roll, and have completed the present invention.

That is, since the surface of the toner obtained by the wet process has a smooth and gentle curved surface without fine irregularities as compared with that of the kneading and pulverizing method, it exhibits a low contact resistance without engaging with the fine irregularities on the surface of the photoreceptor. It is considered that there is a tendency. From this tendency, when assuming that the residual toner is removed from the surface of the photoreceptor by, for example, a doctor blade, the residual toner attempts to be arranged in a translational / fine packing manner,
Further, the toner may enter a portion where the pressing force at the contact nip between the blade and the photosensitive member is strong. At that time, it is presumed that very strong compressive stress and shear stress are generated in the residual toner sandwiched in the contact nip portion between the blade and the photoreceptor. When the surface layer is destroyed, the blade slips through the blade while substantially maintaining the shape of the toner, resulting in poor cleaning. Further, when the toner surface layer is broken near the contact nip between the blade and the photoconductor, toner components mainly including toner external additives slip through the blade, resulting in poor cleaning. It has been found that any of these cleaning failures leads to image failures such as image streaks and unevenness due to charging roll contamination and exposure failures.

However, as in the present invention, the average dispersed particle diameter is 0.01 to 0.5 μm and the melt viscosity is 5.
A low molecular weight fluorine compound selected from the group consisting of polytetrafluoroethylene, a copolymer containing tetrafluoroethylene, a fluoropolyether and a compound containing a perfluoroalkyl group in the range of 5 × 10 ⁴ to 1.0 × 10 ⁸ poise By using the fine particles as an essential component of the toner external additive, the polytetrafluoroethylene fine particles selectively coagulate and break before penetrating deeply into the blade / photoconductor contact nip portion, and the extremely thin low molecular weight fluorine-based compound component The present inventors have found that the residual toner can be easily collected while the layer is formed on the surface of the photoreceptor. Furthermore, the low molecular weight fluorine-based compound component layer formed on the photoreceptor surface in the cleaning step is uniform and has no thickness unevenness, exhibits a lubricating action at the blade / photoreceptor contact nip portion, and reduces wear of the photoreceptor surface. It is also clear that it has contributed.

In the present invention, in addition to the specific addition of the low-molecular-weight fluorine-based compound particles as described above, it is more effective to control the surface composition of the toner particles to improve the cleaning property. That is, the present inventors have found that the surface composition distribution of the toner obtained by the emulsion polymerization aggregation method among the wet manufacturing methods is also one of the accelerating factors that cause the cleaning failure. The conventional emulsion polymerization aggregation method involves mixing a resin dispersion liquid with an ionic surfactant by emulsion polymerization and a pigment dispersed with an ionic surfactant of the opposite polarity to cause hetero aggregation, thereby reducing the toner diameter. There is known a toner manufacturing method in which aggregated particles are formed, and then heated to a temperature equal to or higher than the glass transition point of the resin to fuse and aggregate the aggregates, and then washed and dried. It has also been proposed to control from an amorphous to a spherical shape. Normally, this process is performed by mixing and aggregating at once, so that aggregates in a uniform mixed state are united, so that the surface composition distribution of the toner usually becomes equal to that of the inside. Many.

In particular, when a release agent is contained, the release agent is still present on the surface after the coalescence, and in the cleaning process, partial collapse of the exposed portion of the release agent may cause poor cleaning. It is thought to promote. . As a result of careful examination of the aggregation process and conditions for this phenomenon, in the aggregation process, the balance of the amount of the ionic surfactant of each polarity in the initial stage was shifted in advance, and the first stage of matrix aggregation was performed below the glass transition point. After formation and stabilization, the second step is to add a particle dispersion treated with a surfactant having a polarity and an amount of surfactant to compensate for the imbalance, and furthermore, if necessary, the resin contained in the base or additional particles. After heating slightly below the glass transition point and stabilizing at a higher temperature, heating above the glass transition point keeps the particles added in the second stage of aggregation formation attached to the surface of the parent aggregated particles By coalescing, the surface layer composition produces colored particles unified with the particle composition added in the second step. That is, toner particles having a controlled surface composition are prepared. Further, as an essential component of the external additive, the average dispersed particle diameter is 0.01 to 0.5.
By using fine particles of a specific low molecular weight fluorine compound having a melt viscosity in the range of 5.5 × 10 ⁴ to 1.0 × 10 ⁸ poise, the effect of preventing the occurrence of cleaning of the emulsion polymerization aggregated toner particles can be further improved. I found that I can do it.

Here, the above-described cleaning property improving effect does not necessarily have an effect only on the step of removing the residual toner on the photoconductor, but is applied to the photoconductor (electrostatic image carrier) as exemplified below. It also includes all effects on the process of removing toner from adjacent members. (1) Transfer the developed toner image on the photoreceptor to the intermediate transfer body, superimpose a plurality of types of toner images on the intermediate transfer body, transfer them collectively to a medium such as paper, and then transfer them to the intermediate transfer body. Removing toner remaining in the toner. (2) When the toner removing mechanism is not provided directly on the photoconductor (eg, simultaneous cleaning with the developing mechanism, when the transfer efficiency is maintained at an extremely high level using spherical toner), a very small amount is present on the photoconductor charging member. About the toner to which
Removing the deposits from the charging member to prevent accumulation.

Hereinafter, the toner for electrophotography of the present invention will be described in detail. First, the toner particles used in the electrophotographic toner of the present invention will be described. The toner particles in the present invention contain a binder resin as an essential component, have a volume average particle diameter of 3 to 10 μm, a volume average particle size distribution (GSD) of 1.25 or less, and have a shape factor (ML) of the toner particles. ^ 2 / A) is in the range of 105 to 130. Here, the volume average particle size distribution GSD is obtained by integrating a particle size equivalent to a cumulative volume of 84% by integrating from the small particle size side into d ₈₄ and a cumulative volume of 16% in a cumulative volume particle size distribution curve measured using a Coulter counter. the particle diameter corresponding to a d _16, can be obtained by substituting the ^{_{(d 84 / d 16) 0.5}} . The volume average particle diameter is in the curve, indicating a particle size d ₅₀ corresponding to the cumulative volume of 50%. As a method for producing toner particles having such properties, a polymerizable monomer of a binder resin (binder resin) is polymerized by emulsion polymerization, and a dispersion liquid and a colorant, if necessary, of a release agent Emulsion polymerization aggregation method of mixing, aggregating, heat fusing, and dispersing liquids such as a charge controlling agent, etc. to obtain toner particles, and a polymerizable monomer and a colorant as needed to obtain a binder resin.
A suspension polymerization method in which a solution of a release agent, a charge control agent, etc. is suspended in an aqueous solvent for polymerization, a binder resin and a colorant. If necessary, a solution of a release agent, a charge control agent, etc., is suspended in an aqueous solvent. There is no particular limitation on toners called so-called wet process toners, such as a dissolution suspension method of making the particles turbid, and among them, the emulsion polymerization aggregation method is preferably used because of its high degree of freedom in shape control.

Hereinafter, the emulsion polymerization aggregation method will be described in detail.
The dispersion diameter of the dispersed particles in the dispersion used in the emulsion polymerization aggregation method is desirably 1 μm or less. Also, in the case where toner particles are prepared by the method of forming base aggregated particles described below, it is desirable that the dispersion diameter of both the dispersion liquid for forming base aggregated particles and the additional dispersion be 1 μm or less. If the dispersion diameter of the dispersed particles is larger than that, the distribution of the particle diameter of the finally formed toner particles is widened, or free particles are generated, which tends to cause a reduction in performance and a reduction in reliability. Examples of the polymer serving as the thermoplastic binder resin used in the present invention, styrene, parachlorostyrene, styrenes such as α-methylstyrene,
Methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-methacrylic acid
Ester having a vinyl group such as ethylhexyl, acrylonitrile, vinyl nitriles such as methacrylonitrile, vinyl methyl ethers, vinyl ethers such as vinyl isobutyl ether, vinyl methyl ketone, vinyl ethyl ketone, vinyl ketones such as vinyl isopropenyl ketone, Ethylene, propylene, polymers such as monomers such as polyolefins such as butadiene or copolymers obtained by combining two or more thereof or mixtures thereof,
Further, a non-vinyl condensed resin such as an epoxy resin, a polyester resin, a polyurethane resin, a polyamide resin, a cellulose resin, and a polyether resin, or a mixture of these with the vinyl resin or a vinyl monomer in the coexistence thereof. Examples thereof include a graft polymer obtained at the time of polymerization.

In the case of a vinyl monomer, emulsion polymerization or seed polymerization can be carried out using an ionic surfactant or the like to prepare a resin particle dispersion. If it dissolves in a solvent with relatively low solubility in water, dissolve the resin in those solvents, and disperse the fine particles in water with a disperser such as a homogenizer together with an ionic surfactant or polymer electrolyte in water, and then By heating or reducing the pressure to evaporate the solvent, a resin dispersion can be prepared. Examples of surfactants used for emulsion polymerization, seed polymerization, pigment dispersion, resin particles, release agent dispersion, aggregation, or stabilization thereof include sulfate ester salts, sulfonate salts, phosphate esters, and soaps. Anionic surfactants such as amines, cationic surfactants such as amine salts and quaternary ammonium salts, and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. It is also effective to use them in combination, and as the dispersing means, general means such as a rotary shearing homogenizer, a ball mill having a media, a sand mill, and a dyno mill can be used.

Examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene;
Silicones having a softening point upon heating, fatty acid amides such as oleamide, erucamide, ricinoleamide, stearamide, etc. and carnauba wax, rice wax, candelilla wax, wood wax, jojoba oil, etc. Vegetable wax, animal wax such as beeswax, montan wax, ozokerite, ceresin,
Minerals such as paraffin wax, microcrystalline wax, Fischer-Tropsch wax, petroleum-based wax, and modified products thereof can be used. These waxes are dispersed in water together with ionic surfactants and polymer electrolytes such as polymer acids and polymer bases, and are heated to a temperature above the melting point and subjected to strong shearing by a homogenizer or a pressure discharge type dispersing machine. And a dispersion of particles having a particle size of 1 μm or less can be prepared.

Examples of the coloring agent include carbon black, chrome yellow, Hansa yellow, benzidine yellow, slen yellow, quinoline yellow, and permanent orange.
GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine
3B, Brilliantamine 6B, Dupont Oil Red, Pyrazolone Red, Risor Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green,
Various pigments such as malachite green oxalelate,
Acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, thioindico, phthalocyanine, aniline black, polymethine, triphenylmethane One or more kinds of coloring agents such as various dyes such as diphenylmethane, thiazine, thiazole, and xanthene can be used. In addition, ferrite, magnetite, reduced iron, cobalt, nickel, manganese and other metals, alloys, or magnetic substances such as compounds containing these metals are used as internal additives, and quaternary ammonium salt compounds, nigrosine-based compounds are used as charge control agents. Various commonly used charge control agents such as compounds, dyes composed of complexes of aluminum, iron and chromium, and triphenylmethane pigments can be used. Materials that are difficult to dissolve in water are preferred in terms of control and reduction of wastewater pollution.

Next, in the method of producing toner particles by the emulsion polymerization aggregation method, a description will be given of a method of forming mother aggregate particles in which aggregation can be performed in a plurality of stages, which can control the surface composition of the toner particles. In the method of forming mother aggregate particles, a resin particle dispersion in which resin particles of at least 1 μm or less are dispersed and a colorant dispersion in which a colorant is dispersed are mixed, and the resin particles and the colorant are aggregated (formation of mother aggregate particles). ), Into the dispersion of the base aggregated particles, at least once additional mixing of a particle dispersion of 1 μm or less, and after attaching the particles to the surface of the base aggregated particles, the resin contained in the base aggregated particles and / or the additional particles This is a method for forming toner particles, wherein the toner particles are heated and fused to a temperature higher than the glass transition point.

In this method, the conditions of the aggregation step are as follows:
As described above, the balance of the amount of each polar ionic surfactant in the initial stage is shifted in advance, the first-stage matrix aggregate particles are formed below the glass transition point, and after the stabilization, the balance is performed as the second stage. Add a particle dispersion treated with a surfactant having a polarity and an amount to compensate for the displacement, and further heat the resin slightly below the glass transition point of the resin contained in the base aggregated particles or additional particles as necessary. After stabilizing at a high temperature, the particles added in the second stage of agglomeration are united while being attached to the surface of the parent aggregated particles by heating to a temperature higher than the glass transition point. This method is an effective method from the viewpoint of controlling the surface composition. Moreover, these stepwise operations of aggregation can be performed not only twice as described above, but also repeatedly, so that the composition, and thus the physical properties, can be changed stepwise from the surface to the inside of the toner particles, The structure inside the toner can be controlled very easily.

For example, in the case of a color toner using a multicolor toner, in the first step, a matrix aggregated particle is made of resin particles and pigment particles, and then a resin particle dispersion is added to form only the resin layer on the toner surface. By forming, it is possible to minimize the influence of the pigment particles on the charging behavior. Therefore, in the case of a full-color toner, it is possible to make it difficult for a difference in charging characteristics depending on the types of a plurality of pigments to appear.
Further, if the glass transition point of the resin particles added in the second stage is set higher, the toner is coated in a capsule shape, and as a result, the toner surface strength is uniform and the adverse effect on the cleaning property can be reduced. it can.

When a dispersion liquid of inorganic fine particles is used in the second step, a structure encapsulated by inorganic particles can be formed after coalescence. Examples of the inorganic fine particles to be added by wet method include silica, alumina, titania, calcium carbonate, magnesium carbonate, and tricalcium phosphate, which are all commonly used as external additives on the toner surface, such as ionic surfactants and polymer acids, It can be used by dispersing in a polymer base. Alternatively, in a second step, a release agent particle dispersion such as wax is added, and in a third step, a shell is formed on the outermost surface of the toner particles using a resin or inorganic particle dispersion having high hardness. The wax can effectively act as a release agent during fixing while suppressing exposure.

Alternatively, composite particles of a resin and a pigment can be used as the additional particles, and when these are used, a more complicated hierarchical structure can be realized, and the toner structure can be designed precisely. Become. Preparation of the dispersion containing the composite particles composed of the resin and the pigment is performed by dissolving and dispersing the resin and the pigment in a solvent, and then dispersing in water with an appropriate dispersant as described above, and then heating and reducing the pressure. It can be obtained by removing the solvent. As another method, it can be prepared by mechanically shearing or electrically adsorbing and immobilizing a pigment on the surface of a latex prepared by emulsion polymerization or seed polymerization. Use of the composite particles as described above as the additional particles is effective in suppressing the release of the pigment as the additional particles and improving the pigment dependency of the chargeability.

The amount of the added particle dispersion depends on the volume fraction of the contained particles, and it is desirable that the amount of the added particles be within 50% of the aggregated particles in the volume finally produced.
If it is more than that, the composition distribution and the particle size distribution become remarkable due to the formation of newly aggregated particles instead of aggregation to the base particles, and desired performance cannot be obtained.

As described above, the formation of the aggregated structure on the surface in a stepwise manner suppresses the maintenance of the particle size distribution and the fluctuation of the average particle size from the aggregated particle size during the fusion at the time of high temperature heating after the aggregation. In addition to the above, it is possible to eliminate the need for adding a surfactant such as a surfactant or a base or an acid for improving the stability at the time of the combination, and to minimize the amount of the addition, thereby reducing costs. And quality can be improved. Further, the dispersion liquid whose aggregation structure is controlled so as to correspond to the toner particle diameter is heated and stirred to a temperature not lower than the glass transition temperature of the resin constituting the aggregation structure, and after the coalescence by the stirring shear force and the heating temperature / time. Of the particles can be controlled. Further, by adding the particles stepwise or gradually and continuously, it is possible to suppress the generation of new fine aggregated particles and sharpen the particle size distribution. Further, the generation of free particles can be suppressed by increasing the temperature within the range of the glass transition temperature of the parent aggregated particles or the additional particles at each stage of addition.

The shape of the toner particles in the toner for electrophotography of the present invention can be determined by holding the particles in a dispersed state on a slide glass, photographing a projected image with an optical microscope, and then using an image analyzer (for example, LUZEXIII Co., Ltd.). This is defined by calculating the shape factor ML ^ 2 / A of the particles according to the following equation (2) according to the following formula (2) and taking the number average. Equation (2) ML ^ 2 / A = (maximum length of projected particle image) ² * π * 100 / (area * 4) Here, the shape coefficient ML ^ 2 / A is in the range of 105 to 130, preferably 110. It is preferably in the range of from 130 to 130, more preferably in the range of from 115 to 125. In order to produce particles with a ML ^ 2 / A lower than 105, that is, a particle closer to a true sphere, high-temperature and long-term coalescence conditions must be set. Specifically, the release agent is undesirably deposited on the surface, which causes the above-described cleaning failure. Here, it is known that it is effective to make the shape factor close to 100 in order to improve the transfer performance. However, in actuality, the transfer performance is saturated near the shape factor 110, and the shape factor is actually increased. It is difficult to produce toner particles smaller than 105. Also,
When the shape factor exceeds 130, a toner having a deep concave portion is formed in the emulsion polymerization aggregation method, and an external additive described below is buried in the concave portion and does not function sufficiently.
It is not preferable because there is a problem that particles are easily broken by stress in the developing machine.

Further, in the toner of the present invention, it is preferable to use toner particles having a shape distribution closer to a sphere as the diameter of the toner particles becomes smaller, that is, toner particles satisfying the following expression with respect to the shape coefficient of the toner particles. . M ₅₀ (b)> M ₅₀ (a)> M ₅₀ (c) Here, M ₅₀ is a particle size distribution of a circle equivalent diameter calculated from the projected area of the toner particles, and counted from the side having the larger particle diameter. The average value was obtained by measuring the shape factor of each particle within a specific range of the cumulative number% of the particle number. M ₅₀ (b)
Indicates the average shape factor of particles having a cumulative number% of 16% or less (particles having a larger particle diameter), and M ₅₀ (a) indicates the cumulative number%.
Indicates the average shape factor of particles (particles having an intermediate particle diameter) in the range of 42 to 58%, and M ₅₀ (c) indicates that the cumulative number is 8
It shows the average shape factor of particles of 4% or more (particles with smaller particle size).

Next, the fine particles of the low molecular weight fluorine compound which is a component of the electrophotographic toner of the present invention will be described.
The fine particles of the low molecular weight fluorine compound have an average dispersed particle diameter of 0.01 to 0.5 μm and a melt viscosity of 5.5 × 1.
0 ⁴ to the low molecular weight polytetrafluoroethylene is in the range of 1.0 × 10 ⁸ poise, tetrafluoroethylene-containing copolymer is one or more selected from fluoropolyether and the group consisting of perfluoroalkyl group-containing compound. Here, the average dispersed particle size is a value obtained by taking an image of the dispersed particle size when the fine particles are arranged on the toner surface with an electronic scanning microscope and taking the number average.
If the average dispersed particle diameter of the fine particles of the low molecular weight fluorine-based compound is less than 0.01 μm, the fine particles are easily buried in the toner due to the internal stress, and the cleaning effect cannot be improved. On the other hand, if the average dispersed particle size exceeds 0.5 μm, the fine particles have a problem that the adhesive force to the toner surface is low and the fine particles easily come off in the apparatus before functioning in the cleaning step, which is not preferable. Further, the fine particles of the low-molecular-weight fluorine-based compound is usually such that external additive particles are added to toner particles,
The toner particles may be simply mixed with the toner particles, or may be one that is strongly adhered to the toner surface by applying a shearing force when mixing the toner particles and the fine particles, and the final step of aggregation when the toner particles are manufactured by the aggregation method. In the above, a dispersion liquid of the fine particles may be added so that the fine particles are partially embedded in the surface of the toner particles.

The fine particles of the low molecular weight fluorine compound used in the present invention must have a certain range of molecular weight. However, since this material system has low solubility in solvents, it is generally used to measure the molecular weight of GP.
Since the C (gel permeation chromatography) method cannot be used, the present invention measures the melt viscosity described below, and defines the preferable range based on the measured value. It is necessary that the melt viscosity of the low molecular weight fluorine-containing compound is in the range of 5.5 × 10 ⁴ to 1.0 × 10 ⁸ poise.
It corresponds to 5500 to 35000. The melt viscosity is preferably in the range of 1.0 × 10 ⁵ to 7.0 × 10 ⁷ poise, which is a molecular weight of 6000 to 2500.
It corresponds to 0. The melt viscosity was measured using a flow tester, and the powder of the low-molecular-weight fluorine-based compound was treated with an inner diameter of 11.3 m.
m, and maintained at a temperature of 380 ° C. for 5 minutes. Then, the piston load P (dyne) is arbitrarily set, and an orifice having an inner diameter 2R = 0.21 cm and a length L = 0.8 cm is extruded and discharged (Q : Cm 2 / sec), and the melt viscosity is determined according to equation (2).

Formula (2) Melt viscosity (poise) = (P * 2R * π * R ³ ) / (16 * L * Q) If the melt viscosity is lower than 5.5 × 10 ⁴ poise, the molecular weight is too low. In the pre-process in which the material functions in the cleaning process, in particular, in the developing process, the particles tend to cause fusion filming on the member, which deteriorates the developing performance, which is not preferable. On the other hand, if the melt viscosity exceeds 1.0 × 10 ⁸ poise, the molecular weight is high, and the above-described effect of improving the cleaning property cannot be obtained, which is not preferable.

The low molecular weight fluoropolymer used in the present invention includes polytetrafluoroethylene (PTF).
E), a copolymer of tetrafluoroethylene and Stern monomers, the major structural unit -C _n F _2n -O- _(n is fluoropolyethers having integer from 1 to 4), the main structure

[0038]

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Examples of the compound include a perfluoroalkyl group-containing compound having 2 to 20 carbon atoms. Specific brand names of the low molecular weight polytetrafluoroethylene used in the present invention include Lubron L2, Lubron L5,
Lubron L5F (manufactured by Daikin Industries, Ltd.), KTL-500
F, KTL-8 (manufactured by Kitamura), Vidax AR (manufactured by DuPont), Fluon Lubricant L169 (manufactured by Asahi Glass) and Fomblin Z25 and Fomblin Y2 as low molecular weight fluoropolyethers.
5 (manufactured by Montefluos) and Demnum (manufactured by Daikin Industries, Ltd.), but are not limited thereto.
Some of these exemplified products have an average particle size of a single material larger than the range of 0.01 to 0.5 μm, but fall within the scope of the present invention due to shear or preliminary grinding when externally added to the toner. What is necessary is just to process. Examples of the perfluoroalkyl group-containing compound include a polymer of a reaction product of a compound having a reactive group as shown below and an ethylenically unsaturated compound (for example, fluoroalkyl acrylate, etc.); Examples include a reaction product of a compound having an alkyl group and various polymers having a group that reacts with the reactive group, or a polycondensate of the aforementioned compound.

[0040]

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Further, as a method for externally adding fine particles of a low-molecular-weight fluorine-based compound to toner particles used in the present invention, in the above-mentioned emulsion polymerization aggregation method, a low-molecular-weight For example, a method of adding fine particles of a fluorine-based compound in the form of a dispersion and fixing the fine particles to the toner surface layer can be used. As another method, after the aggregated particles are dried, the aggregated particles (toner particles) and the fine particles of the low-molecular-weight fluorine-containing compound are mixed in a dry state by shearing in the same manner as a normal toner, so that the surface of the toner particles is reduced. A method of adding fine particles of a fluorine compound having a molecular weight may be used. Further, a mixture of toner particles and fine particles of the low molecular weight fluorine-based compound may be used.

The addition amount is from 0.1 to 5 parts by weight, more preferably from 0.3 to 3 parts by weight, per 100 parts by weight of the toner particles.
It is set in the range of parts by weight. Further, at this time, similarly to the known toner, inorganic particles such as silica, alumina, titania and calcium carbonate, resin fine particles such as vinyl-based resin, polyester, and silicone, long-chain fatty acids and esters thereof.
An amide, a metal salt, or the like may be used together with the toner surface or added stepwise to impart a function as a fluidity aid or a charge control aid.

The two-component developer of the present invention contains the toner for electrophotography and a carrier. As the carrier used in the two-component developer, materials such as iron powder, glass beads, ferrite powder, nickel powder or particles obtained by applying a resin coating on the surface thereof, and particles obtained by dispersing magnetic powder in resin into spherical particles can be used. . The electrophotographic toner of the present invention can be used not only as a two-component developer but also as a one-component developer.

Further, the present invention provides a process for forming an electrostatic latent image on an electrostatic image carrier, a process for developing the electrostatic latent image with a developer, a process for transferring the developed image to a transfer medium,
The present invention also relates to an image forming method having a cleaning step for removing residual toner, wherein a developer containing the toner of the present invention described above is used as the developer. The developer of the present invention is used for developing an electrostatic latent image formed on an electrostatic image carrier (photoconductor) or an electrostatic recording medium. That is, an electrostatic latent image is electrophotographically formed on an electrostatic image carrier made of an inorganic photoconductive material such as selenium, zinc oxide, cadmium sulfide, and amorphous silicon, and an organic photoconductive material such as a phthalocyanine pigment and a bisazo pigment. And
Alternatively, an electrostatic latent image is formed on an electrostatic recording medium having a dielectric material such as polyethylene terephthalate using a needle-shaped electrode or the like, and the electrostatic latent image is formed on the electrostatic latent image by a developing method such as a magnetic brush method, a cascade method, or a touch-down method. The toner of the present invention is attached to form a toner image. Here, as the developing method,
For example, a so-called one-component development method in which a toner layer is formed on a sleeve and developed by facing the electrostatic image carrier, a developer layer is formed on the sleeve by mixing toner and magnetic carrier particles, and an electrostatic latent image carrier is formed. A so-called two-component development method in which development is performed by facing each other is preferably applicable. In particular, when the toner particle diameter is 6 μm or less, the two-component developing method is more preferable from the viewpoint of toner charge controllability. In any of the developing methods, it is preferable to superpose a DC electric field and an alternating electric field between the developing sleeve and the electrostatic latent image carrier. The parameter of the alternating electric field can be selected at any time according to the toner particle size, the distance between the sleeve latent image carriers, and the like.

This toner image is then transferred to a transfer medium. That is, after being transferred to an intermediate transfer body as a transfer medium, or directly without being transferred to the intermediate transfer body,
After the image is transferred to a transfer medium such as paper, the image is fixed and becomes a copy.
The toner remaining on the surface of the electrostatic image carrier and / or the member adjacent to the electrostatic image carrier, that is, the charging member or the intermediate transfer member is cleaned. As the cleaning method, a cleaning method using a blade pressure bonding, a web fur brush cleaning method, a roll method, an electrostatic brush method, or the like can be used. In particular, when the electrophotographic toner of the present invention is used in an image forming method including a step of cleaning residual toner by pressing with a rubber blade, excellent cleaning properties are exhibited.

[0046]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the following examples. Example 1 <Preparation of Resin Dispersion 1> Styrene 360 g n-butyl acrylate 40 g Acrylic acid 6 g Dodecanethiol 24 g 4 Carbon bromide 4 g or more were mixed and dissolved, and a nonionic surfactant Nonipol 400 6 g and an anionic interface were mixed and dissolved. In a flask prepared by dissolving 10 g of activator Neogen SC in 550 g of ion-exchanged water, 50 g of ion-exchanged water in which 4 g of ammonium persulfate was dissolved was added while dispersing and emulsifying in a flask for 10 minutes, followed by nitrogen replacement.
Then, stir the contents of the flask in an oil bath to
C. and the emulsion polymerization was continued for 5 hours. This gives a center diameter of 160 nm, a glass transition point of 59 ° C, and Mw of 13500
Was obtained.

<Preparation of Resin Dispersion 2> 300 g of styrene, 100 g of n-butyl acrylate, and 8 g or more of acrylic acid were mixed and dissolved, and 6 g of nonionic surfactant Nonipol 400 and 12 g of anionic surfactant Neogen SC were ion-exchanged with water. To the solution dissolved in 550 g, while dispersing and emulsifying in a flask and slowly mixing for 10 minutes, 50 g of ion-exchanged water in which 3 g of ammonium persulfate was dissolved was added, and the atmosphere was replaced with nitrogen. Thereafter, the contents were heated to 70 ° C. in an oil bath while stirring the flask, and emulsion polymerization was continued for 5 hours. Thus, the center diameter is 100 nm, the glass transition point is 54 ° C., and Mw is
450,000 anionic resin dispersion liquid 2 was obtained.

<Preparation of Pigment Dispersion 1> Carbon black Mogal L (Cabot) 50 g Nonionic surfactant Nonipol 400 5 g Deionized water 200 g or more were mixed and dissolved, and dispersed by a homogenizer (IKA Ultra Turrax) for 10 minutes. Thus, a carbon black dispersion having a center particle diameter of 250 nm was obtained.

<Preparation of Release Agent Dispersion 1> Paraffin wax HNP0190 (melting point 85 ° C. Nippon Seisaku) 50 g Cationic surfactant Sanisole 50 (Kao) 5 g Deionized water 200 g or more heated to 95 ° C. After dispersion by Ultra Turrax T50, dispersion treatment was performed by a pressure discharge type homogenizer to obtain a wax dispersion having a center diameter of 520 nm.

<Preparation of Aggregated Particles A> Resin Dispersion 1 130 g Resin Dispersion 2 70 g Pigment Dispersion 30 g Release Agent Dispersion 40 g Sanizol B50 1.5 g or more in a round stainless steel flask using Ultra Turrax T50 After mixing and dispersing, the flask was heated to 48 ° C. while stirring in a heating oil bath. After holding at 48 ° C. for 40 minutes, observation with an optical microscope confirmed that aggregated particles of about 5 μm had been formed. Here, 75 g of Resin Dispersion 1 was gently added, and the temperature of the heating oil bath was further increased and maintained at 50 ° C. for 1 hour. When observed with an optical microscope,
It was confirmed that aggregated particles of 6.2 μm were generated.

Then, after adding 3 g of Neogen SC,
The stainless steel flask was sealed, heated to 105 ° C. while stirring with a magnetic seal, and held for 4 hours. After cooling, the mixture was filtered, washed sufficiently with ion-exchanged water, and the particle size was measured using a Coulter counter. The result was 6.2 μm, and the volume GSD, which is an index of the volume particle size distribution, was 1.25. The shape factor SF of the produced particles was measured and found to be 121. The aggregated particles A are dried and taken out, and 0.5 parts by weight of silica particles having an average particle diameter of 12 nm and 1.0 parts by weight of silica particles having an average particle diameter of 40 nm are added to 100 parts by weight of the particles A. Polytetrafluoroethylene emulsion polymerized particles Lubron L having a melt viscosity of 5.0 × 10 ⁵ poise at 0.3 μm
2 (Daikin Industries) 1.0 part by weight was added and mixed with a Henschel mixer to prepare a black toner. After preparation
Observation of the dispersed particle size of polytetrafluoroethylene dispersed on the surface of the toner showed 0.3 μm.

Example 2 <Preparation of Resin Dispersion 3> Styrene 330 g n-butyl acrylate 70 g Acrylic acid 8 g Dodecanethiol 12 g 4 Carbon bromide 4 g A mixture prepared by dissolving at least 4 g or more was mixed with a nonionic surfactant Nonipol 400 (Sanyo). 6g and 10g of anionic surfactant Neogen SC (Daiichi Kogyo Seiyaku) dissolved in 550g of ion-exchanged water are dispersed and emulsified in a flask and slowly mixed for 10 minutes while dissolving 4g of ammonium persulfate 50 g of the ion-exchanged water thus obtained was added, and nitrogen replacement was performed. Thereafter, the contents were heated to 70 ° C. in an oil bath while stirring the flask, and emulsion polymerization was continued for 6 hours. Thus, an anionic resin dispersion having a center diameter of 180 nm, a glass transition point of 54 ° C. and Mw of 20,000 was obtained.

<Preparation of Resin / Pigment Composite Dispersion> Polyester resin (bisphenol A-fumaric acid-propylene oxide adduct Mw12000 Tg57 ° C.) 50 g Methylene chloride 100 g Phthalocyanine pigment (PV FAST BLUE) 5 g or more mixed and dissolved in a ball mill And dispersed in 150 g of pure water containing 10% polyethylene glycol and 0.7% neogen SC,
Disperse with strong shearing in Ultra Turrax, 60 ℃
To obtain a polyester / pigment composite particle dispersion having an average diameter of 850 nm.

<Preparation of Pigment Dispersion 2> Phthalocyanine Pigment (PV FAST BLUE) 100 g Nonionic surfactant Nonipol 400 5 g Ion-exchanged water 200 g or more were mixed and dissolved, and the mixture was dissolved in a rotor stator type homogenizer (IKA Ultra Turrax). After that, the mixture was further dispersed with an ultrasonic homogenizer for 5 minutes to obtain a cyan pigment dispersion having a center particle diameter of 150 nm.

<Preparation of Particle Dispersion> Fluoropolyether particles Fobulin Z25 ground particles (manufactured by Montefluos) 20 g Cationic surfactant Sanisole B50 (Kao) 8 g Ion-exchanged water 200 g or more were mixed and dissolved, and a homogenizer (IKA Ultra Tarra) was dissolved.
) For 20 minutes.
A polyether particle dispersion was obtained. Full used for this dispersion
Oropolyether particles have an average particle size of 0.2 μm
The viscosity is 5.0 × 10 ⁶Poise.

<Preparation of Agglomerated Particles B> Resin dispersion 3 200 g Pigment dispersion 2 15 g Sanizol B50 2 g or more were mixed and dispersed in a round stainless steel flask by Ultra Turrax T50, and the flask was heated in an oil bath for heating. Heat to 48 ° C. with stirring. After maintaining at 48 ° C. for 60 minutes, observation with an optical microscope confirmed that aggregated particles of about 7.0 μm had been formed. Here, 50 g of the resin / pigment composite dispersion was gradually added, and the temperature of the oil bath for heating was further increased and maintained at 50 ° C. for 30 minutes. Observation with an optical microscope confirmed that aggregated particles of about 7.5 μm had been formed. 10 g of a fluoropolyether particle dispersion 1 was further added thereto, and the temperature was further raised and maintained at 53 ° C. for 1 hour. Although almost no change in the average dispersed particle size was observed, it was confirmed that the fluoropolyether particles added last had adhered to the surface of the aggregated particles.

Then, after adding 2 g of Neogen SC,
The stainless steel flask was sealed, heated to 105 ° C. while stirring with a magnetic seal, and held for 3 hours. After cooling, the mixture was filtered, washed sufficiently with ion-exchanged water, and measured for particle size with a Coulter counter to find that the particle size was 7.4 μm. The volume GSD, which is an index of volume particle size distribution, was 1.23. The shape factor SF was 136. The aggregated particles B are dried and taken out, and the average particle diameter is 20 nm with respect to 100 parts by weight of the particles B.
Was added and 1.0 part by weight of silica particles having an average particle size of 50 nm was added and mixed with a Henschel mixer to prepare a cyan toner. After preparation, the dispersion particle size of the fluoropolyether dispersed on the surface of the toner was 0.2 μm.

Example 3 <Preparation of Aggregated Particles C> Resin Dispersion 1 180 g Resin Dispersion 2 100 g Pigment Dispersion 1 30 g Release Agent Dispersion 1 40 g Sanizol B50 1.6 g or more in a round stainless steel flask After mixing and dispersing with a Turrax T50, the flask was heated to 50 ° C. while stirring in a heating oil bath. After holding at 50 ° C. for 90 minutes, observation with an optical microscope confirmed that aggregated particles of about 6.3 μm had been formed. Then here neogen
After adding 3 g of SC, the stainless steel flask was sealed, and heated to 105 ° C. while stirring with a magnetic seal.
Hold for hours. After cooling, the mixture was filtered, sufficiently washed with ion-exchanged water, and the particle size was measured with a Coulter counter to be 6.2 μm. The volume GSD, which is an index of the volume particle size distribution, is 1.2
3. The shape factor SF was 107. The aggregated particles C are dried and taken out, and 100 parts by weight of the aggregated particles C are 0.8 parts by weight of titania particles having an average particle diameter of 20 nm, 1.9 parts by weight of silica particles having an average particle diameter of 80 nm, and 0.7 parts by weight.
2.0 parts by weight of polytetrafluoroethylene particles having a melt viscosity of 6.0 × 10 ⁷ poise (KTL-500F, manufactured by Kitamura Co., Ltd.) were added and mixed with a Henschel mixer to prepare a black toner. After the preparation, the dispersion particle size of polytetrafluoroethylene dispersed on the toner surface was 0.4 μm.

Comparative Example 1 A toner was prepared in the same manner as in Example 1 except that polytetrafluoroethylene particles were not used as an external additive in the preparation of the toner of Example 1.

Comparative Example 2 In the preparation of the toner of Example 2, the average particle size was 0.1% instead of the fluoropolyether particles used in preparing the particle dispersion.
A toner was prepared in the same manner as in Example 2 except that polytetrafluoroethylene emulsion polymerization particles having a melt viscosity of 3.0 × 10 ¹¹ poise and a particle diameter of 3 μm were used. At this time, the average dispersed particle size of the polytetrafluoroethylene particles was 0.3 μm.
m.

Comparative Example 3 The procedure of Example 3 was repeated except that the polytetrafluoroethylene particles added as an external additive were replaced with polytetrafluoroethylene particles having an average particle size of 1.5 μm and a melt viscosity of 7.2 × 10 ⁷ poise. Are all in the third embodiment. A toner was prepared with the same prescription. At this time, the average dispersed particle size of the polytetrafluoroethylene particles was 0.7 μm.

[Evaluation] Carrier 1 comprising 6 parts by weight of each prepared toner and 50 μm Cu—Zn ferrite coated with 0.5% by weight of polymethyl methacrylate
00 parts by weight were mixed with a blender to prepare a two-component developer. Further, these developers were put into an Acolor 635 copying machine, and a copy test of 10,000 sheets was performed. DC component -500V as development bias, Vp as AC superposition component
A superimposed rectangular wave having a frequency of -p1.5 kV and a frequency of 6 kHz was applied to the developing sleeve to perform a print test.
For cleaning, a method in which a urethane rubber blade was pressed against the surface of the photoreceptor was used. Table 1 shows the results.

[0063]

[Table 1]

As shown in Table 1, when an image was formed using a toner to which polytetrafluoroethylene resin fine particles having a specific particle diameter and melt viscosity of the present invention were externally added, 10,000 copies or more were formed. In this case, no cleaning failure occurred. Also, there was no influence on the development and transfer performance, and good image quality was obtained. On the other hand, when such a toner not using the fine particles of the polytetrafluoroethylene resin is used, a cleaning failure occurs at the time of 1600 sheets, and the black spot is 2,500 sheets at the time of 2000 sheets as a secondary obstacle. A streak occurred at the time of (Comparative Example 1). When a polytetrafluoroethylene resin having a molecular weight higher than that of the present invention was used, cleaning failure occurred at 3,500 sheets, and streaks occurred at 4000 sheets (Comparative Example 2). Further, the particle diameter is 0.8 μm
When a polytetrafluoroethylene resin larger than that of the present invention was used, cleaning failure occurred at 30 sheets, and a black band occurred at 100 sheets (Comparative Example 3).
From these examples, it is understood that it is important that the particle diameter and the melt viscosity of the polytetrafluoroethylene resin used as the external additive are included in appropriate ranges.

According to the present invention, toner particles having a specific particle size range and particle shape are combined with a fluororesin or a compound having a specific particle size range and melt viscosity, and this is externally added to the toner particles. By using the toner for electrophotography, in the image formation using the toner, it is possible to obtain excellent cleaning characteristics while maintaining the development and transfer performance, and the obtained image is excellent in image quality and has a secondary obstacle. do not do.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Chiaki Suzuki 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. F-term (reference) 2H005 AA08 AA15 CA11 EA03 EA05 FA02

Claims (3)

[Claims] 1. A toner containing a binder resin as an essential component, having a volume average particle diameter of 3 to 10 μm, a volume average particle size distribution (GSD) of 1.25 or less, and a shape factor (ML ^ 2) of the toner particles. / A) is an electrophotographic toner containing toner particles having a range of 105 to 130, wherein the toner has an average dispersed particle diameter of 0.01 to 0.5 μm and a melt viscosity of 5.
A low molecular weight fluorine-based compound selected from the group consisting of polytetrafluoroethylene, a copolymer containing tetrafluoroethylene, a fluoropolyether and a compound containing a perfluoroalkyl group in the range of 5 × 10 ⁴ to 1.0 × 10 ⁸ poise; An electrophotographic toner comprising at least one compound fine particle. 2. A two-component developer comprising the electrophotographic toner according to claim 1 and a carrier. 3. A step of forming an electrostatic latent image on an electrostatic image carrier, a step of developing the electrostatic latent image with a developer, a step of transferring the developed image to a transfer medium, and a step of forming an electrostatic image. A cleaning step of removing a toner remaining on a member adjacent to the carrier and / or the electrostatic image carrier, wherein the developer containing the toner according to claim 1 is used as the developer. Characteristic image forming method.