JP2625804B2 - Electrostatic latent image developing toner and method of manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a toner for developing an electrostatic latent image.
More specifically, the present invention relates to an electrostatic latent image developing toner for developing an electrostatic latent image in electrophotography, electrostatic recording, and electrostatic printing.

(Prior Art) Development of an electrostatic latent image in electrophotography, electrostatic recording, and electrostatic printing involves electrostatically adsorbing triboelectrically charged toner to an electrostatic latent image formed on a photoconductor. This is done by visualization.

As a method for charging a toner used in the development of such an electrostatic latent image, in a two-component development system, it is known that charge is applied by mixing and stirring with a substance generally called a carrier. It is also known that charge is applied by contact with a developing sleeve, a toner regulating blade, or the like even in a one-component developing system. Either method causes problems during development and transfer if the toner is not uniformly charged.

Conventionally, dry toners are generally prepared by melt-mixing a pigment such as carbon black into a thermoplastic resin to form a uniform dispersion, and then pulverizing the powder into a powder having a particle size required as a toner by an appropriate pulverizer. Has been manufactured. Although the toner produced by such a so-called pulverization method can have various excellent performances, it also has various disadvantages. That is, since the steps of mixing and melting and pulverization are required, the mixture is fluidized at an appropriate temperature so that the pigment and the like can be uniformly mixed. It is required to be able to process at a considerable speed. However, if a material which is easily crushed is used, it is liable to be further crushed in an electrophotographic copying machine or the like, which leads to defects such as contamination of the device and occurrence of image fogging. Further, if a material which is easily melted is used, there is a possibility that the toner may be caked and the surface of the photoconductive layer may be stained (toner filming).

In addition, when the pigment buried in the resin appears on the surface during pulverization, partial non-uniformity of triboelectric charging characteristics may occur, and furthermore, a problem also occurs in moisture resistance depending on the type of the pigment. It is possible.

An even greater drawback is that the toner produced by the pulverization method has an irregular shape, which tends to cause aggregation between toner particles, stability during storage of the toner, dispensing characteristics during toner supply, In addition, it is considered that the effect on the sharpness of the developed image and the cleaning characteristics in the case of repeated use are also considered to be a desirable factor, and this has a great effect on the actual obtained image quality, particularly on the resolution, sharpness, fog, etc. It is a problem. In addition, the toner produced by the pulverization method generally has a wide particle size distribution depending on the degree of classification, and thus the charge amount of each toner particle is different and the charge amount distribution is wide. Fogging and the like occur, which is a problem particularly during printing.

In recent years, with respect to toner for developing an electrostatic latent image, higher definition in terms of line reproducibility, texture, dot reproducibility,
Higher image quality is required in terms of gradation and resolution, and it is desired to reduce the particle size of toner particles in order to achieve this purpose. On the other hand, in the two-component developing method, powder properties such as fluidity as a mixture with a carrier are deteriorated. For this reason, if the toner having an irregular shape and a wide particle size distribution obtained by the pulverization method as described above is reduced in particle size, the fluidity is extremely reduced. Even if added, side effects such as poor charging and increased scattering properties are caused.

On the other hand, for toners manufactured by these pulverization methods,
For example, as shown in JP-B-36-10231, JP-B-43-10799 and JP-B-51-14895, a polymer composition containing a polymer monomer, a polymerization initiator and a colorant is used as a non-solvent. There is also known a toner obtained by suspending in a system dispersion medium and polymerizing, that is, a suspension polymerization method. The toner obtained by such a suspension polymerization method has spherical particles and is generally considered to have excellent fluidity. However, these toners have a wide particle size distribution, and therefore the size of the toner is reduced. And its liquidity was not yet sufficient. In addition, such toners require a classification process during manufacture,
In addition, there still remains a problem in control of the charging property. That is, in the suspension polymerization method, a charge control agent having an influence on the polymerization reaction cannot be used. The problem of charge amount distribution due to the wide distribution occurs.

Furthermore, as the toner for developing an electrostatic latent image, in order to cope with the functions and applications of the above-described toner having higher definition, higher image quality, or diversification, compounding is performed for the purpose of separating functions or improving surface properties. Various structured toners have also been proposed.

For example, JP-A-61-275767 discloses a layer comprising a magnetic substance and / or a colorant on the surface of a core particle, and at least one kind of monomer selected from a fluorine-containing monomer, an amino group-containing monomer and a nitro group-containing monomer. A toner formed by laminating a capsule layer made of a polymer of a monomer containing a monomer by a wet method, and Japanese Patent Publication No. 59-38583 discloses a coating layer made of fine particles formed on the surface of core particles by emulsion polymerization. And JP-A-62-226162 discloses a toner in which fine resin particles are attached to the surface of a colored thermoplastic resin by a wet method and then subjected to a heat treatment. In these toners, focusing on the fact that the electrical properties of the toner mainly depend on the surface portion thereof, resin particles are attached to the surface of core particles containing a colorant, a magnetic substance, etc., and the resin layer is formed. It is intended to achieve stable charging properties depending on physical properties or surface shape.
However, in these publications, the shape of the core particles or the toner itself is not strictly specified, and the spherical particles obtained by the general suspension polymerization as described above may be used as the core particles. It is also possible to use irregularly shaped spherical particles obtained by a pulverization method. Therefore, these toners also have the same problems of fluidity and charge amount distribution as described above, especially when the particle size is reduced. there were. Further, in these toners, the fine resin particles which cover the surface of the core particles in a wet manner adhere to the core particles while maintaining the particle shape, as is clear from the electron micrograph shown in JP-A-62-226162. Therefore, the coating layer formed from the fine resin particles does not completely cover the surface of the core particles (that is, is not dense). Therefore, even if the charge control agent is added to the fine resin particles in the toner having such a configuration, there is a high possibility that stable chargeability may not be obtained due to the influence of the colorant, the magnetic powder, and the like in the core particles. ,
In particular, when the toner is stored or used under severe temperature conditions, components constituting the core particles leach out from the gaps between the fine resin particles to the toner surface, which has a greater effect. In addition, when the core particle component invades the toner surface in this way, there is also a problem that the toner particles are simultaneously aggregated. In addition,
Japanese Patent Application Laid-Open No. 61-275767 discloses that the particle size distribution of toner particles is within ± 20% of the average particle size based on the average particle size is 70% by weight or more. However, no comparison of characteristics with those having a particle size distribution outside this range is disclosed, and in such a relatively loose rule, the fluidity associated with the reduction in the particle size of the toner particles,
It has not been possible to solve the problem of the charge amount distribution and the deterioration of the image quality during printing. In addition, a polar group-containing polymer imparts chargeability as disclosed in JP-A-61-275767 or fine particles on the toner surface as disclosed in JP-B-59-38583 and JP-A-62-226162. Both the increase in friction coefficient due to the presence and the provision of chargeability by the increase in surface area do not provide sufficient chargeability, and the rise of charge due to these is slow, so that the variation in charge amount due to the difference in stirring time is reduced. It was a cause of occurrence.

(Problems to be Solved by the Invention) Accordingly, an object of the present invention is to provide a novel toner for developing an electrostatic latent image which solves the above-mentioned problems. SUMMARY OF THE INVENTION It is an object of the present invention to provide a toner for developing an electrostatic latent image having a sufficient fluidity and a narrow charge amount distribution even when the particle diameter is further reduced. It is still another object of the present invention to provide a toner for developing an electrostatic latent image, which can quickly and stably maintain a sufficient charge amount. The present invention further provides chargeability, developability, transferability, and cleaning that sufficiently correspond to high definition in terms of line reproducibility, high image quality in terms of texture, halftone dot reproducibility, gradation, and resolution. It is an object of the present invention to provide an electrostatic latent image developing toner having powder characteristics such as fluidity and fluidity. The present invention further facilitates the diversification of toners for developing electrostatic latent images, such as the positive and negative polarities of toner charging, colorization, and further, the wide usage from low speed to high speed. It is an object of the present invention to provide a toner for developing an electrostatic latent image that can be obtained.

(Means for Solving the Problems) The above objects are at least a core particle made of a colorant and a thermoplastic resin, and an outer shell made of at least a charge control agent and a synthetic resin and coated on the outer surface of the core particle to form a film. In a toner for electrostatic development comprising a layer, the core particles have a number average molecular weight (Mn) of 3,000 to 20,000 and a molecular weight distribution (Mn).
(w / Mn) 10 to 70 thermoplastic resin, the coefficient of variation of the particle diameter of the toner for developing an electrostatic latent image itself is less than 15%, and the shape factor SF1 is 150 or less. This is achieved by a toner for developing an electrostatic latent image.

The above objects are also achieved by electrostatically attaching fine particles made of a synthetic resin to the surface of a core particle made of a thermoplastic resin having at least a colorant and a number average molecular weight (Mn) of 3,000 to 20,000 and a molecular weight distribution (Mw / Mn) of 10 to 70. Forming a shell layer formed by melting the surface of the attached fine particles by mechanical shearing force, and melting and fixing a charge control agent to the shell layer. This is achieved by a method for producing a toner for developing an electrostatic latent image.

The variation coefficient of the particle size obtained in the present specification is,
It represents a measure (%) of variation in particle size, and is obtained by dividing a standard deviation (σ) in particle size by an average particle size, and is obtained as follows. That is, first take a photograph with a scanning electron microscope and randomly
Select 100 particles and measure the particle size. The standard deviation (σ) and the average particle size are determined based on the measurement results. Note that the standard deviation (σ) used in the present invention is a value obtained by dividing the square of the difference from the average value of each measured value when n particle diameters are measured by (n−1). Expressed as the square root. That is, it is represented by the following equation.

Where x ₁ , x ₂ … x _n are the measured values of the particle size of the sample particles, x
Is the average of each of the n measurements. The standard deviation (σ) thus obtained was divided by the average particle diameter (), and a value multiplied by 100 was defined as a variation coefficient.

The shape factor SF1 used in the present specification is:
It is used as a parameter indicating the difference (distortion) between the major axis and the minor axis of the particle, and generally indicates the sphericity of the powder particle, and is defined by the following equation. Each value shown in the present specification was measured by an image analyzer (Luzex 5000, manufactured by Nippon Regulator Co., Ltd.).

(In the formula, the area indicates the average value of the projected area of the powder, and the maximum length indicates the average value of the maximum length in the projected image of the powder.) Therefore, the closer the shape of the toner particles is to a true sphere, the more The value of the shape factor SF1 is close to 100.

The present inventors have conducted intensive studies in view of the influence of the shape and particle size distribution of the toner particles on the fluidity and charge amount of the toner particles as described above. A resin material having a narrow diameter distribution is used as a core material, and a desired laminated structure is formed using the resin particles as a core material without substantially changing the particle size distribution and shape of the core material particles. When the latent image developing toner has a very high sphericity and a narrow particle size distribution as described above, even if the size of the toner particles is reduced,
The present invention has been found to be able to impart high fluidity and stable uniform charging characteristics, and to provide a toner exhibiting stable developability without causing problems such as fogging and toner scattering.

Hereinafter, the present invention will be described in more detail based on embodiments.

The electrostatic latent image developing toner of the present invention has a laminated structure in which resin particles mainly composed of a thermoplastic resin are used as a core material.

The resin particles used as the core material have a coefficient of variation of the particle size of less than 10%, more preferably less than 8%. Also, in order to obtain a high sphericity as the final toner particles by forming a laminated structure, the resin particles used as the core material are naturally spherical, that is, the spherical coefficient SF1 is 120 or less, preferably 115 or less Is used. The method for obtaining such spherical resin particles having a narrow particle size distribution is not particularly limited, but for example, granulation using a method known as seed polymerization can be preferably exemplified. That is, as shown in JP-B-57-24369, a part of the polymerizable monomer and a polymerization initiator are added to an aqueous medium or an aqueous medium containing an emulsifier, and the mixture is stirred and emulsified. The remaining monomer is gradually dropped to obtain fine particles, and the particles are used as seeds to perform polymerization in polymerizable monomer droplets. In addition, it is possible to dissolve or disperse the colorant in the polymerizable monomer to granulate the resin particles containing the colorant, but in order to stably obtain more uniform resin particles, the colorant is added. It is desired not to.

Preferred examples of the thermoplastic resin constituting such resin particles include homopolymers and copolymers of various vinyl monomers as described below. That is, as the vinyl monomer, for example, styrene, o
-Methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn -Octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-methoxy styrene, p-phenyl styrene, p
Styrene and derivatives thereof, such as -chlorostyrene and 3,4-dichlorostyrene, among which styrene is most preferred. Other vinyl monomers include, for example, ethylene, propylene, butylene, isobutylene, ethylenically unsaturated monoolefins, vinyl chloride, vinylidene chloride, vinyl bromide, vinyl halides such as vinyl fluoride, vinyl acetate, Vinyl esters such as vinyl propionate, vinyl benzoate and vinyl acetate, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, acrylic acid 2-ethylhexyl, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, α-methyl methacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacrylate Acrylic acid-propyl,
Α such as n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc.
-Methylene aliphatic monocarboxylic acid esters, (meth) acrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl methyl ketone, vinyl hexyl Examples thereof include vinyl ketones such as ketone and methyl isopropenyl ketone, N-vinyl compounds such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, and N-vinyl pyrrolidone, and vinyl naphthalenes.

In addition, as a polymerization initiator used when polymerizing the polymerizable monomer to obtain desired resin particles as described above, an arbitrary polymerization initiator, particularly an oil-soluble polymerization initiator is used in a normal temperature range. Specific examples of the polymerization initiator include 2,2 ′
-Azobisisobutyronitrile, 2,2'-azobis-2,4
Dimethylvaleronitrile, azo compounds such as 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, acetylcyclohexylsulfonyl peroxide,
Diisopropyl peroxydicarbonate, decanoyl peroxide, lauroyl peroxide, stearoyl peroxide, acetyl peroxide, t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, t-butylperoxyisobutyrate, cyclohexanone Peroxides such as peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide and cumene hydroperoxide. The amount of these polymerization initiators used is
0.01 to 10 parts by weight, more preferably 0.5 to 100 parts by weight
-5 parts by weight. That is, if the amount is less than 0.01 part by weight, the polymerization rate is slow, while if it is more than 10 parts by weight, it becomes difficult to control the polymerization.

The plastic resin constituting the resin particles serving as the core material has a glass transition temperature (Tg) of 70 ° C. or lower, preferably 30 to
60 ° C., number average molecular weight (Mn) 3000-20000, preferably 4
000 to 12000 and a molecular weight distribution (Mw / Mn) of 10 to 70, preferably 15 to 40 are characteristics desired for obtaining a higher fixing property of the toner.

In the toner for developing an electrostatic latent image of the present invention, a colorant layer is usually formed on the surface of such a spherical resin particle having a narrow particle size distribution.

The method for forming the colorant layer containing the colorant on the surface of the resin particles is not particularly limited, and only the colorant is wet- or dry-processed on the surface of the resin particles serving as the core material by van der Waals. After being attached by the action of force and electrostatic force, it can be attached and fixed to the base particles by heat or mechanical impact, or the coloring agent can be attached and fixed together with the thermoplastic resin fine particles or contains a coloring agent It is also possible to adhere and fix thermoplastic resin particles.

As the colorant to be attached to the resin particles serving as the core material in the toner for developing an electrostatic latent image of the present invention, various organic or inorganic pigments and dyes as shown below can be used.

That is, examples of black pigments include carbon black, copper oxide, manganese dioxide, aniline black, and activated carbon.

As a yellow pigment, graphite, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, banza yellow G, banza yellow 10G, benzidine yellow G, benzidine yellow GR, There are quinoline yellow lake, permanent yellow NCG, tartrazine lake and so on.

As the orange pigment, red lead, molybdenum orange,
Permanent Orange GTR, Pyrazolone Orange, Vulcan Orange, Indus Len Brilliant Orange RK,
Benzidine Orange G and Indus Len Brilliant Orange GK.

Red pigments include red iron, cadmium red, lead red, mercury sulfide, cadmium, permanent red 4R, lithol red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, Alizarin Lake, Brilliant Carmine 3B and others.

Examples of purple pigments include manganese purple, fast violet B, and methyl violet lake.

Examples of blue pigments include dark blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, fast sky blue, and indaslen blue BC.

Green pigments include chrome green, chromium oxide, pigment green B, micalite green lake, final yellow green G, and the like.

Examples of white pigments include zinc white, titanium oxide, antimony white, and zinc sulfide.

The extender includes baryte powder, barium carbonate, clay, silica, white carbon, talc, alumina white and the like.

Various dyes such as basic, acidic, disperse, and direct dyes include nigrosine, methylene blue, rose bengal, quinoline yellow, and ultramarine blue.

These colorants may be used alone or in combination of two or more, but may be used in an amount of 1 to 20 parts by weight, more preferably 2 to 10 parts by weight, based on 100 parts by weight of the resin contained in the toner particles. desirable. That is, when the amount is more than 20 parts by weight, the fixing property of the toner is deteriorated. On the other hand, when the amount is less than 1 part by weight, a desired image density may not be obtained.

Further, in the electrostatic latent image developing toner of the present invention, the coloring material layer formed on the surface of the core material composed of the resin particles as described above is usually covered with a synthetic resin coating layer containing a charge control agent. ing. In other words, if such a configuration is adopted, the polarity of the charge, the chargeability, and the developing property are hardly influenced by the configuration of the colorant layer or the core material existing inside, and by the configuration of the synthetic resin coating layer as the outer shell layer. Properties and the like, and even if the colorant or the like contained in the core particles changes, stable and uniform chargeability can be imparted between the toner particles. In addition, the charge control agent can perform effective charge control by being localized in the outer shell layer, which is the outermost surface of the toner particles. It can provide a good chargeability. Further, since the resin particles as the core material are covered with the synthetic resin coating layer, for example, as described above, the thermoplastic resin contained in the resin particles constituting the core material is softened to improve the fixing property. Even when using a low-point synthetic resin, by using a synthetic resin with a relatively high softening point as a synthetic fiber constituting the synthetic resin coating layer,
The heat resistance and environmental resistance of the toner particles can be improved, and both functions can be compatible.

In the electrostatic latent image developing toner of the present invention, the charge control agent contained in the synthetic resin coating layer may be mixed with the synthetic resin to constitute the synthetic resin coating layer, or may be present on the surface of the synthetic resin coating layer. Or both. The outer shell layer is composed of at least a charge control agent and a synthetic resin, but a fluidizing agent, an anti-offset agent and the like can be added to the outer shell layer as needed.

As a method of forming a synthetic resin coating layer that further covers the colorant layer formed on the outer surface of the core material as described above, a core material having a colorant layer formed thereon and a small particle size for the core material may be used. More specifically, about 1/5 or less of microparticles (ie, synthetic resin microparticles, synthetic resin microparticles and charge control agent microparticles, or synthetic resin microparticles containing a charge control agent) are machined at an appropriate mixing ratio. And then uniformly adhering the microparticles around the core material formed with the colorant layer by the action of van der Waals force and electrostatic force, and then immobilizing the microparticles. A preferred method is to soften the fine particles by a local temperature rise caused by force or the like to form a film. The resin fine particles for forming the outer shell layer used here have an average particle size of 0.05 to 3 μm, preferably 0.1 to 1 μm, and a coefficient of variation of the particle size distribution of 2 μm.
0% or less, preferably 15% or less is used.
Powders with an average particle size smaller than 0.05 μm are difficult to manufacture, and larger than 3 μm or a coefficient of variation of 20%
If it is larger, it is difficult to form a coating on the surface of the core particle. Further, it is desirable to use spherical fine particles in performing the coating film forming process. According to such a method, without substantially changing the shape and particle size distribution of the core material composed of resin particles having a high sphericity and a narrow particle size distribution as described above, and to the resin particles serving as the core material Even if the synthetic resin contained in the synthetic resin coating layer has a higher softening point than the thermoplastic resin contained, it can easily form the outer shell layer that substantially completely covers the outer surface of the core particles. is there. The surface properties of the toner particles obtained in this manner are the composition of core particles and outer shell layer forming particles,
By selecting physical properties (particle size, thermal properties, gelling components, etc.), smoothness and surface roughness can be changed by further selecting processing conditions and the number of times of processing. It is desirable that the toner particles have a spherical shape and minute irregularities on the surface in view of characteristics such as fluidity, cleaning property and chargeability of the toner particles. In addition, as a device that can be suitably used in such a method, a hybridization system (Nara Machinery Co., Ltd.) using a high-speed airflow impact method, an ng mill (manufactured by Hosokawa Micron Corporation), a mechano mill (Okada Seiko ( Co., Ltd.).

However, as a method of forming the synthetic resin coating layer,
The method is not limited to the above method as long as the variation coefficient and shape factor SF1 of the finally obtained toner particles are in the desired ranges as described above.

Further, in the embodiment in which the charge control agent is adhered to the surface portion of the synthetic resin coating layer, the charge control agent is adhered to the surface of the outer shell layer formed as described above by the method described above, and then fixed by mechanical impact force or the like. Just do it. However, it is of course not limited to such a method.

The synthetic resin contained in the synthetic resin coating layer may be any resin, for example, a styrene resin, a (meth) acrylic resin, an olefin resin obtained by polymerizing a monomer as shown below. , Thermoplastic resins such as polyester resins, amide resins, carbonate resins, polyethers, polysulfones,
In other words, a thermosetting resin such as an epoxy resin, a urea resin, a urethane resin and the like, and a copolymer and a polymer blend thereof are used. As the synthetic resin contained in the synthetic resin coating layer, for example, not only those in a state of a perfect polymer as in a thermoplastic resin, but also those in an oligomer or a prepolymer state as in a thermosetting resin, A polymer partially containing a prepolymer, a crosslinking agent, or the like can also be used.

Specific examples of the monomers constituting such a synthetic resin include the following. That is, as the vinyl monomer, the styrene monomer, ethylenically unsaturated monoolefin monomer, vinyl halide monomer, vinyl ester monomer, α
A methylene aliphatic monocarboxylic acid ester monomer,
Examples include (meth) acrylic acid derivative monomers, vinyl ether monomers, vinyl ketone monomers, N-vinyl compound monomers, and vinylnaphthalene monomers. Further, as a monomer for obtaining a polyester resin, terephthalic acid, isophthalic acid,
Examples thereof include adipic acid, maleic acid, succinic acid, sebacic acid, thioglycolic acid, and diglycolic acid. Examples of glycols include ethylene glycol, diethylene glycol, 1,4-bis (2-hydroxyethyl) benzene, , 4-cyclohexanedimethanol, propylene glycol and the like. In addition, as a monomer for obtaining an amide resin, caprolactam, and further as a dibasic acid, terephthalic acid, isophthalic acid, adipic acid, maleic acid, succinic acid, sebacic acid, thioglycolic acid, and the like can be given, and diamines include , Ethylenediamine, diamineethylether, 1,4
-Diaminobenzene, 1,4-diaminobutane and the like.

As monomers for obtaining urethane resins, diisocyanates include p-phenylene diisocyanate and p-
Xylene diisocyanate, 1,4-tetramethylene diisocyanate, and the like.Examples of glycols include ethylene glycol, diethylene glycol,
Propylene glycol, polyethylene glycol and the like can be mentioned.

As a monomer for obtaining a urea resin, diisocyanates include p-phenylene diisocyanate, p-xylene diisocyanate, 1,4-tetramethylene diisocyanate, and the like.Diamines include ethylenediamine, diaminoethyl ether, 1,4
-Diaminobenzene, 1,4-diaminobutane and the like.

Examples of the monomers for obtaining the epoxy resin include amines such as ethylamine, butylamine, ethylenediamine, 1,4-diaminobenzene, 1,4-diaminobutane, and monoethanolamine.The diepoxy compounds include diglycidyl. Examples thereof include ether, ethylene glycol diglycidyl ether, bisphenol A diglycidyl ether, and hydroquinone diglycidyl ether.

As the synthetic resin for forming the synthetic resin coating layer, a synthetic resin obtained by polymerizing the above monomers alone or in combination of a plurality of kinds can be used. A polymer of a monomer component having a group or fluorine, a copolymer of a monomer as described above and a monomer component having a nitrogen-containing polar functional group or a fluorine as described below, or by polymerizing the monomer as described above A polymer blend of the above polymer and a polymer of a monomer component having a nitrogen-containing polar functional group or fluorine as described below may be used. When a synthetic resin having a polar group introduced is used for the synthetic resin coating layer, the charge control agent contained in the outer shell layer can be reduced in a smaller amount because the synthetic resin itself functions as a charge controller. Can be imparted with a chargeability.

The nitrogen-containing polar functional group is effective for positive charge control, and the monomer having the nitrogen-containing polar functional group is represented by the following general formula (I) (In the formula, R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are hydrogen or an alkyl group having 1 to 20 carbon atoms, X is an oxygen atom or a nitrogen atom, and Q is an alkylene group or an arylene group.) Amino (meth) acrylic monomers.

Representative examples of amino (meth) acrylic monomers include N, N-dimethylaminomethyl (meth) acrylate, N, N-diethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminobutyl (meth) acrylate, p-N, N-dimethylaminophenyl (meth) acrylate, p-N , N-diethylaminophenyl (meth) acrylate, pN, N-dipropylaminophenyl (meth) acrylate, pN, N-dibutylaminophenyl (meth) acrylate, pN-laurylaminophenyl (meth) acrylate , P-N-stearylaminophenyl (meth) acrylate, p-N, N-dimethylamino Njiru (meth) acrylate, p-N, N- diethylamino-benzyl (meth) acrylate, p-N, N- dipropyl aminobenzyl (meth) acrylate, p-N, N
-Dibutylaminobenzyl (meth) acrylate, p-
N-laurylaminobenzyl (meth) acrylate, p
—N-stearylaminobenzyl (meth) acrylate and the like are exemplified. Further, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide, p- N, N-dimethylaminophenyl (meth) acrylamide, p-N, N-diethylaminophenyl (meth) acrylamide, p-N, N
-Dipropylaminophenyl (meth) acrylamide,
pN, N-dibutylaminophenyl (meth) acrylamide, pN-laurylaminophenyl (meth) acrylamide, pN-stearylaminophenyl (meth)
Acrylamide, pN, N-dimethylaminobenzyl (meth) acrylamide, pN, N-diethylaminobenzyl (meth) acrylamide, pN, N-dipropylaminobenzyl (meth) acrylamide, p-N, N- Dibutylaminobenzyl (meth) acrylamide, p-N
-Laurylaminobenzyl (meth) acrylamide, p
—N-stearylaminobenzyl (meth) acrylamide and the like.

Fluorine atoms are effective in controlling the negative charge, and the fluorine-containing monomer is not particularly limited. For example, 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, Preferred examples include fluoroalkyl (meth) acrylates such as 2,3,3,4,4,5,5-octafluoroamyl acrylate and 1H, 1H, 2H, 2H-heptadecafluorodecyl acrylate. Besides, trifluorochloroethylene, vinylidene fluoride, ethylene trifluoride, ethylene tetrafluoride, trifluoropropylene, hexafluoropropene, hexafluoropropylene and the like can be used.

Incidentally, the synthetic resin forming the synthetic resin coating layer may be the same as the thermoplastic resin constituting the resin particles as the core material, or may be different,
Desirably, in order to achieve higher heat resistance of the toner particles, it is desirable that the glass transition temperature be 60 ° C. or higher and the glass transition temperature of the thermoplastic resin constituting the core material.

The amount of the synthetic resin forming the synthetic resin coating layer is 5 to 50 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the core material forming the colorant amount. That is, if the amount of the synthetic resin forming the synthetic resin layer is less than 5 parts by weight, it becomes difficult to completely cover the outer surface of the colorant layer with the synthetic resin coating layer, and the colorant component is exposed on the surface of the toner particles. This is because there is a possibility that stable and uniform charging properties may be impaired, whereas if it exceeds 50 parts by weight, a uniform synthetic resin coating layer cannot be formed, and the required particle size distribution or particles are required. This is because there is a risk of deviating from the definition of the shape.

In the electrostatic latent image developing toner of the present invention, the charge control agent contained in the synthetic resin coating layer is not particularly limited as long as it can give a positive or negative charge by triboelectric charging, and various organic or inorganic charge control agents can be used. Can be used.

As the positive charge control agent, for example, Nigrosine Base EX
(Orient Chemical Industry Co., Ltd.), quaternary ammonium salt P-51 (Orient Chemical Industry Co., Ltd.), Nigrosine Bontron N-01 (Orient Chemical Industry Co., Ltd.),
Sudan Chief Schwarz BB (Solvent Black 3: Co
lor Index 26150), Fettschwarz HBN (C.IN)
O.26150), brilliant spirits Schwarz TN (manufactured by Farben-Fablicken Bayer), Zavonschwarz X (manufactured by Falberge Hoechst), alkoxylated amines, alkylamides, molybdate chelate pigments, and the like. As the negative charge control agent,
For example, Oil Black (Color Index 26150), Oil Black BY (Orient Chemical Industry Co., Ltd.), Bontron S-2 (Orient Chemical Industry Co., Ltd.), Salicylic acid metal complex E-81 (Orient Chemical Industry Co., Ltd.) Thioindigo pigment, sulfonylamine derivative of copper phthalocyanine, Spiron Black TRH (manufactured by Hodogaya Chemical Industry Co., Ltd.), Bontron S-34 (manufactured by Orient Chemical Industry Co., Ltd.), Nigrosine SO (Orient Chemical Industry ( stock)
), Ceres Schwarz (R) G (Farben Fabriken Bayer), Kromogen Schwarm @ ETOO
(CINO. 14645), Azo Oil Black (R) (manufactured by National Aniline Co.) and the like.

These charge control agents can be used alone or in combination of two or more, but the amount of the charge control agent added to the synthetic resin coating layer is based on 100 parts by weight of the synthetic resin forming the synthetic resin coating layer. 0.001 to 10 parts by weight, preferably 0.
01 to 5 parts by weight. That is, if the addition amount is less than 0.001 part by weight, the amount of the charge control agent present on the surface of the toner particles is small, so that the charge amount of the toner is insufficient. This is because the charge control agent may be peeled off from the layer, spent on the surface of the carrier, or mixed into the developer to deteriorate the printing durability.

As described above, the electrostatic latent image developing toner of the present invention has a laminated structure in which resin particles containing a thermoplastic resin as a main component have a core material, and the laminated structure has excellent charge stability, It has properties such as heat resistance and fixability, but above all the coefficient of variation of its particle size is less than 15%, preferably 10%
And the shape factor SF1 is 150 or less, preferably 140 or less, so that the average particle size is 14 μm or less, more preferably 10 μm or less as a small particle size is sufficient. It exhibits stable chargeability with a narrow flowability and charge amount distribution, and exhibits uniform and stable developability.

(Examples) Hereinafter, the present invention will be described more specifically with reference to examples.

Toner Production Example a Monodisperse spherical styrene obtained by a seed polymerization method
100 parts by weight of a copolymer polymer of n-butyl methacrylate (average particle size: 8 μm, coefficient of variation: 5%, shape factor SF: 108, glass transition temperature: 54 ° C., Mn: 10,000, Mw / Mn: 25) 8 parts by weight of carbon black (manufactured by Mitsubishi Chemical Corporation: MA # 8) was placed in a 10 Henschel mixer and mixed and stirred at a rotation speed of 1500 rpm for 2 minutes to attach the carbon black to the surface of the polymer particles. Next, a carbon black was immobilized on the surface of the polymer particles by performing a treatment at 9,000 rpm for 3 minutes using Nara Machine Hybridization System NHS-1.

Polymer particles treated with the above carbon black
100 parts by weight and polymethyl methacrylate particles (MP-1451 manufactured by Soken Chemical Co., Ltd., average particle size: 0.15 μm, coefficient of variation: 5
%, Shape factor SF1: 106, glass transition temperature: 125 ° C.), 10 parts by weight were subjected to the same treatment as above to form a PMMA resin coating layer formed into a film. Furthermore, the polymer particles 100 obtained here
0.5 parts by weight of a negative charge control agent chromium complex type dye Spiron Black TRH (manufactured by Hodogaya Chemical Industry Co., Ltd.) to 0.5 parts by weight of the negative charge control agent
TRH was fixed to the toner surface to obtain a toner a of Example 1 having an average particle size of 9.0 μm, a variation coefficient of 8%, and a shape factor SF1 = 132.

Toner Production Example b In the toner production example a, CuFeO ₄ —CuMn was used as a colorant.
₂ O ₄ ^{* 1} (Dainichi Seika Industry Co., Ltd.) [ ^{* 1} CuFe ₂ O ₄ -CuMn
_The particle size distribution of the ₂ O _{4 by} the light transmission type particle size distribution analyzer is 0.0
The average diameter is between 0.1 and 0.2 μm. The oil absorption is 35cc / 100g. ] The average particle diameter of the toner of Example 2 is the same as that of Example 2 except that
A toner b having 9.0 μm, a variation coefficient of 8%, and a shape factor SF1 = 127 was obtained.

Toner Production Example c To form a colorant layer in Toner Production Example a, in addition to 8 parts by weight of carbon black (MA # 8 manufactured by Mitsubishi Kasei Kogyo Co., Ltd.), PMMA particles MP-1451 (Soken Chemical Co., Ltd.) (Average particle size: 0.15 μm, coefficient of variation: 5%, shape factor SF: 106, glass transition temperature: 125 ° C.) The toner of Example 3 was produced in the same manner except that 5 parts by weight was used as a colored layer material. Average particle size 9.5μ
m, a coefficient of variation 8%, and a toner c having a shape factor SF1 of 136 were obtained.

Toner Production Example d PMMA particles (MP-1000 manufactured by Soken Chemical Co., Ltd., average particle size: 0.4
μm, coefficient of variation: 7%, shape factor SF1: 107, glass transition temperature: 125 ° C), added in a composition ratio of 10 parts by weight, put in a Henschel mixer, and mixed and stirred at 1500 rpm for 2 minutes to form carbon black on the surface of PMMA particles. Was attached. Next, a carbon black was immobilized on the surface of the polymer particles by performing a treatment at 9000 rpm for 3 minutes using Nara Machine Hybridization System NHS-1. The toner of Example 4 was 9.8 μm, and the coefficient of variation was 8%, in the same manner as in Production Example a of the toner except that the obtained colorant-containing particles were used as a colorant-forming material, and 15 parts by weight were changed to carbon black. Thus, a toner d having a shape factor SF = 138 was obtained.

Toner Production Example e Except for using 0.5 part by weight of the positive charge control agent Nigrosine dye Bontron N-01 (manufactured by Orient Chemical Industry Co., Ltd.) in place of the charge control agent Spiron Black TRH used in Toner Production Example a. By the same method, toner e of Example 5 having an average particle diameter of 9.0 μm, a variation coefficient of 8%, and a shape factor SF1 = 131 was obtained.

Toner Production Example f Styrene-n-butyl methacrylate copolymer (average particle size) obtained by a suspension polymerization method instead of the monodisperse spherical core material particles obtained by the seed polymerization method used in the toner production example a. Diameter: 8 μm, coefficient of variation 25%, shape factor SF1: 110,
Glass transition temperature: 57 ° C., Mn: 12000, Mw / Mn: 30), except that the toner of Comparative Example 1 had an average particle diameter of 9.3 μm, a coefficient of variation of 24%, and a shape factor of the toner of Comparative Example 1 except that the Mn was 12,000 and Mw / Mn was 30). SF1
= 121 was obtained.

Production Example of Toner g Component 70 parts by weight of styrene 30 parts by weight of n-butyl methacrylate 2,2-azobis- (2,4-dimethylvaleronitrile) 0.5
Parts by weight Carbon black MA # 18 (Mitsubishi Chemical Industries, Ltd.) 8
3 parts by weight Chromium complex salt dye Spiron Black TRH (manufactured by Hodogaya Chemical Industry Co., Ltd.) 3 parts by weight
A polymerizable composition was prepared. This polymerizable composition was put into a 3% by weight aqueous solution of gum arabic by a stirrer "TK Auto Homomicser" (manufactured by Tokushu Kika Kogyo Co., Ltd.) at 4000 rpm.
While stirring at m, a polymerization reaction was carried out at a temperature of 60 ° C. for 6 hours, and the temperature was further raised to a temperature of 80 ° C. to carry out a polymerization reaction. After the completion of the polymerization reaction, the reaction system was cooled, washed with water 5 to 6 times, dried after passing through, and then subjected to air classification to obtain spherical particles.

The average particle size of the obtained spherical particles was 8.1 μm, the glass transition point (Tg) was 61 ° C., the number average molecular weight (Mn) was 8,000, and the molecular weight distribution (Mw / Mn) was 22.

The variation coefficient of the particle size distribution of the toner was 21%, and the shape factor SF1 was 118. The toner obtained here is referred to as a toner g of Comparative Example 2.

Production Example of Toner h Component by weight styrene-n-butyl methacrylate resin (glass transition point, 60 ° C., Mn: 8000, Mw / Mn: 21) 100 carbon black (MA # 8, manufactured by Mitsubishi Chemical Industry Co., Ltd.) 8 Chromium complex salt type dye Spiron Black TRH (manufactured by Hodogaya Chemical Industry Co., Ltd.) 3 The above materials were sufficiently mixed by a ball mill, and then kneaded on three rolls heated at 140 ° C. The kneaded material was allowed to cool, coarsely pulverized using a feather mill, and finely pulverized using a jet mill. Next, air classification was performed, and the average particle size was 8.8 μm.
m, the toner h of Comparative Example 3 having a particle size distribution variation coefficient of 22% and a shape factor SF1 = 163.

Production Example of Styrene-Acrylic Resin Fine Particles In a three-necked flask equipped with a stirrer, a condenser, an inert gas inlet tube, and a thermometer, 70 parts by weight of a styrene monomer and 25 parts by weight of n-butyl methacrylate were used as a dispersion. 5 parts by weight of n-butyl acrylate, 1.5 parts by weight of a polymerization initiator benzoyl peroxide, 2% of a completely saponified polyvinyl alcohol (degree of polymerization: about 1000) and 1,000 ml of sodium dodecylbenzenesulfonate in 1000 cc of distilled water as a dispersion medium. Using 1% of the mixture, they are mixed in a liquid tank, and the turbine is set to 1500 rp using "TK Auto Homomixer" manufactured by Tokushu Kika Kogyo Co., Ltd. as a mixing and dispersing means.
The mixture was mixed and dispersed at 12000 rpm while gradually increasing the rotation speed from m. The dispersion mixture was heated at 80 ° C. for 6 hours while stirring at the final rotation speed to carry out polymerization.

After completion of the polymerization, the mixture was passed through a centrifugal dehydrator, washed eight times with pure water, vacuum-dried and crushed, and had a number average molecular weight Mn of 10,000, a molecular weight distribution of Mw / Mn = 2.4, a glass transition point of 60 ° C, and a softening point of 120 ° C. Styrene-acrylic resin microparticles having a particle size of 0.5 μm, a variation coefficient of 14%, and a shape factor SF1 of 113 were obtained.

Toner Production Example k Monodisperse spherical styrene obtained by seed polymerization method
n-butyl methacrylate copolymer (average particle size: 7 μm, coefficient of variation: 5%, glass transition temperature: 65 ° C., Mn: 1)
2,000, Mw / Mn: 20)] and 100 parts by weight of a phthalocyanine pigment (CI74160) in a 10 Henschel mixer.
The mixture was mixed and stirred at a rotation speed of 500 rpm for 2 minutes to cause the pigment to adhere to the surface of the polymer particles. Next, the pigment was immobilized on the surface of the polymer particles by performing a treatment at 9000 rpm for 3 minutes using Nara Machine Hybridization System NHS-1.

Further, 100 parts by weight of the polymer particles treated with the pigment and the fine particles obtained in the production example of the styrene-acrylic resin particles
20 parts by weight were provided with a resin coating tank by the same treatment as above. Further, 0.5 part by weight of a negative charge control agent chromium complex type dye E-81 (manufactured by Orient Chemical Industry Co., Ltd.) was treated in the same manner as described above with respect to 100 parts by weight of the obtained polymer particles to obtain E. −81 was fixed to the toner surface, and the toner of Example 6 had an average particle size of 9.2 μm, a variation coefficient of 9%,
A toner i having a shape factor SF1 = 139 was obtained.

Toner Production Example j Except for replacing the pigment with 3 parts by weight of Brilliant Carmine 6B (CI 15850) and the charge control agent with 0.5 parts by weight of E-81 (manufactured by Orient Chemical Industry Co., Ltd.) in Toner Production Example a. Using the same composition and manufacturing method, a toner j of Example 7 having an average particle size of 9.2 μm, a variation coefficient of 8%, and a shape factor SF1 = 131 was obtained.

Toner Production Example k The toner of Example 8 having an average particle diameter of 9.1 was prepared using the same composition and production method as in toner production example j except that the pigment was changed to 3 parts by weight of benzidine yellow (CI 21090).
μm, a coefficient of variation of 8%, and a shape coefficient SF1 = 132 were obtained for the toner k.

Production Example 1 of Toner The same composition and production method were used as in Production Example j of toner except that the negative charge control agent was replaced with 1.0 part by weight of a positive charge control agent P-51 (manufactured by Orient Chemical Industries, Ltd.). The average particle diameter of the toner of Example 9 was 9.2 μm and the coefficient of variation was 8.
% And a shape factor SF1 = 126.

Production Example m of Toner In the production example a of the toner, the particles obtained by the seed polymerization method used as the core material were subjected to glass transition point Tg = 56 ° C.
Number average molecular weight Mn = 7000 Molecular weight distribution Mw / Mn = 38, Coefficient of variation 5%, Shape coefficient SF1 = 110 A toner m having a diameter of 8.1 μm, a variation coefficient of 8%, and a shape factor SF1 = 133 was obtained.

Toner Production Example n In Toner Production Example a, particles obtained by a seed polymerization method used as a core material were subjected to glass transition point Tg = 51 ° C.
Number average molecular weight Mn = 15,000, molecular weight distribution Mw / Mn = 4, particle size 7.
Comparative Example 4 using the same composition and manufacturing method except that the composition was 0 μm, the coefficient of variation was 5%, and the shape factor SF1 was 110.
The toner n having an average particle diameter of 8.2 μm, a variation coefficient of 8%, and a shape factor SF1 = 132 was obtained.

Manufacturing component parts by weight of the polyester resin of the carrier A (softening point 123 ° C., a glass transition point 65 ℃, AV23, OHV40) (manufactured by TDK (Ltd.)) 100 Fe-Zn ferrite fine particles MFP-2 500 Carbon black (Mitsubishi Chemical Industries ( 2) The above materials were sufficiently mixed and pulverized with a Henschel mixer, and then melted and kneaded using an extruder kneader set at a cylinder section of 180 ° C and a cylinder head section of 170 ° C. The kneaded product was left to cool, coarsely pulverized using a feather mill, finely pulverized using a jet mill, and then classified using a classifier to obtain a carrier A having an average particle diameter of 60 μm.

Parts by weight of carrier B components Magnetite (BL-SP, manufactured by Titanium Industry Co., Ltd.) 500 Stinylene-acrylic copolymer resin (Priolite ACL, manufactured by Goodyear Chemical Co., Ltd.) 100 Silica # 200 (Nippon Aerosil Co., Ltd.) 2) The above components were sufficiently mixed with a super mixer, kneaded with a single screw extruder, crushed with cooling, crushed with a hammer mill to an average particle size of 50 μm, and classified into coarse and fine powder with an air classifier. A carrier B having an average of 40 μm was obtained. When measuring the specific gravity
It was 3.3 g / cm ³ .

Evaluation method for various properties Examples 1 to 10 and Comparative Example 1 thus obtained
Various properties of the toners a to n were evaluated as described below. The post-treatment was carried out with 0.1 parts by weight of colloidal silica R-972 (manufactured by Nippon Aerosil Co., Ltd.) based on 100 parts by weight of each of the toners a to n, and used for evaluating various characteristics.

Amount of charge (Q / M) and amount of scattering Here, 2 g of the surface-treated toner, 28 g of the prescribed carrier shown in Table 1, and a 50 cc plastic bottle are placed on a rotary mount and rotated at 1200 rpm. In order to examine the rise of the charging plate, the charge amount after stirring for 3, 10 and 30 minutes was measured, and the scattering amount at that time was examined.

The scattering amount was measured with a digital dust meter P5H2 type (manufactured by Shibata Chemical Co., Ltd.). The dust meter and magnet roll are
cm, and after setting 2 g of developer on this magnet roll, when the magnet is rotated at 2000 rpm, the dust meter reads the toner particles that are generated as dust and counts for 1 minute. Display in a few cpm.
Table 1 shows the measurement results of the charge amount and the scattering amount.

Evaluation of Image Deposition A predetermined toner and carrier shown in Table 2 were mixed at a ratio of toner / carrier = 7/93 to prepare a two-component developer. Using this developer, Examples 1 to 4, 6 to 8 and 1
0, EP-570Z (manufactured by Minolta Camera Co., Ltd.) for Comparative Examples 1-4, and EP-47 for Examples 7 and 12.
Initial image evaluation (and printing durability test) was performed using 0Z (manufactured by Minolta Camera Co., Ltd.), and various image evaluations shown in Table 2 were performed.

1) Fogging on Image As described above, in the combination of various toners and carriers, image formation was performed using the above copying machine. Regarding the fog on the image, the toner fog on the white background image was evaluated and ranked. Although it can be practically used at the rank of Δ or higher, it is preferable that the rank is at least ○.

2) ID and image quality A standard chart of DataQuest was copied under appropriate exposure conditions under the same conditions as above, and the ID and image quality were evaluated by the following methods. The solid image density is measured by a Sakura densitometer and ranked.The image quality is evaluated by using a standard chart of DataQuest to determine the gradation, resolution, line reproducibility, fineness of the texture on the image, etc. Comprehensive evaluation and ranking were performed. Both of them are practically usable on the △ rank, but ○ or more is desirable.

3) Printing durability test The above EP-570Z was used for Examples 1 to 6, 8 to 11 and 13 to 14 and Comparative Examples 1 to 4, and for Examples 7 and 12,
A 100,000-sheet press life test was performed using EP-470Z. At this time, the toner charge amount and fog were evaluated.

Fixability test In addition, the initial image was copied on paper and an OHP sheet, and the fixability was evaluated. The fixing strength was ◎, 15 to 20 times when the image was not disturbed even after rubbing more than 20 times using sand eraser.
The number of times was evaluated as ○, 5 to 15 times as Δ, and less than 5 times as ×. The results are shown in Table 2.

(Effects of the Invention) As described above, the toner for developing an electrostatic latent image of the present invention comprises a core particle composed of at least a colorant and a thermoplastic resin, and a core particle composed of at least a charge control agent and a synthetic resin. In the toner for electrostatic development composed of an outer shell layer having a surface coated and formed into a film, the core particles have a number average molecular weight (Mn) of 3,000 to 20,000 and a molecular weight distribution (Mw / Mn) of 10 to 70.
And the variation coefficient of the particle diameter of the electrostatic latent image developing toner itself is less than 15%, and the shape factor SF1 is 1
It is characterized by being 50 or less, showing sufficient fluidity even when the particle size is reduced, the distribution of the charge amount is narrow, and the charge amount is stable, so that fog, toner scattering, etc. It shows stable developability without causing any problem.

In addition, taking advantage of the advantages of the laminated structure, in terms of its functions, for example, it is possible to easily achieve compatibility between heat resistance and fixability, etc. This is very advantageous because it is possible to easily cope with the situation by changing only the necessary parts according to the functions.

Continuation of the front page (72) Inventor Koichi Sano 2-30 Azuchicho, Higashi-ku, Osaka-shi, Osaka Osaka International Building Minolta Camera Co., Ltd. (56) References JP-A-58-205161 (JP, A) JP-A Sho 62-205367 (JP, A) JP-A-61-275766 (JP, A) JP-A-61-275767 (JP, A) JP-A-59-64854 (JP, A) JP-A-60-117255 (JP, A A)

Claims (4)

(57) [Claims] 1. An electrostatic developing device comprising a core particle comprising at least a colorant and a thermoplastic resin, and an outer shell layer comprising at least a charge control agent and a synthetic resin and having a film formed on the outer surface of the core particle. In the toner, the core particles have a number average molecular weight (Mn) of 3,000 to 20,000 and a molecular weight distribution (Mw / M
n) An electrostatic latent image comprising a thermoplastic resin having a particle size of 10 to 70, and a coefficient of variation of a particle diameter of the toner for developing an electrostatic latent image itself is less than 15%, and a shape factor SF1 is 150 or less. Image developing toner. 2. The electrostatic latent image developing toner according to claim 1, wherein said charge control agent is melt-fixed on said outer shell layer. 3. The coefficient of variation of the particle size of the core particles is less than 10%,
2. The electrostatic latent image developing toner according to claim 1, wherein the shape factor SF1 is 120 or less, and the synthetic resin forming the outer shell layer is fine particles having a variation coefficient of less than 20%. . 4. A colorant and a number average molecular weight (M
n) a process of electrostatically attaching fine particles of synthetic resin to the surface of core particles of thermoplastic resin having a molecular weight distribution (Mw / Mn) of 10 to 70, and a mechanical shearing force on the surface of the attached fine particles. A process for forming an outer shell layer formed by fusing and forming a film, and a step of melting and fixing a charge controller to the outer shell layer.