JP2014067021A - Toner for electrostatic charge image development - Google Patents

Abstract

An object of the present invention is to provide a toner for developing an electrostatic image having excellent image quality, low-temperature fixability and environmental stability.
A toner having toner base particles containing at least a binder resin and a colorant and an external additive, wherein the toner base particles have a core-shell structure having core particles and shell particles. The above problem is solved by the toner for developing an electrostatic charge image, wherein the ratio of the projected area of the shell particles to the projected area of the core particles after sonication is 25% or more and 60% or less.
[Selection] Figure 1

Description

  The present invention relates to an electrostatic charge image developing toner excellent in high image quality, low-temperature fixability and environmental stability.

The toner for developing an electrostatic charge image is used for image formation for visualizing an electrostatic charge image in a printer, a copying machine, a facsimile, or the like. For example, when an image is formed by electrophotography, an electrostatic latent image is first formed on a photosensitive drum, then developed with toner, transferred to transfer paper, and fixed by heat or the like. Image formation is performed.
As a toner for developing an electrostatic image, usually, a binder resin and a colorant are mixed with a charge control agent, a release agent, a magnetic material, etc., if necessary, and then melt-kneaded with an extruder or the like, and then pulverized. For the purpose of imparting various properties such as fluidity to the toner particles obtained by the so-called melt-kneading and pulverizing method, for example, solid fine particles such as silica are attached to the surface as external additives Is used.

Suspension polymerization, emulsion polymerization agglomeration, and dissolution suspension methods that require high-definition image quality in image formation of copying machines, printers, etc., and that make it easier to control the particle size and particle size distribution of toner particles than the melt-kneading pulverization method Such polymerization methods have been proposed.
In recent years, with the spread of copiers and printers in recent years, in addition to demands for image quality, toners that are particularly excellent in high-speed printing and low-energy fixing properties have been desired, and attempts have been made to improve low-temperature fixing properties of toners. It has been. In order to achieve low-temperature fixing, a method of lowering the glass transition point of the binder resin or using a crystalline resin in combination is often used, but what is low-temperature fixability, blocking resistance, and high-temperature offset resistance? However, there is usually a trade-off between the two, and it is desirable to achieve both.

  In response to these problems, a hard shell layer is formed on the surface of the toner base particles composed of a low-viscosity resin excellent in low-temperature fixing such as a capsule structure, thereby maintaining resistance to low-temperature fixing of the toner. A method for improving the blocking property is also often used. However, it is difficult to control the shell layer. If the shell layer is too thick, the low-temperature fixability of the toner deteriorates. Conversely, if the shell layer is too thin, the shell layer is embedded in the toner base particle layer or the core portion. It is difficult to obtain the expected anti-blocking performance when the binder resin component is exposed on the toner surface.

  For example, in Patent Document 1, by forming a granular convex portion integrated with a coverage of 10% to 80% with respect to the surface of the toner core and making a controlled structure, both low-temperature fixing and heat-resistant storage stability can be achieved. I'm trying. Patent Document 2 attempts to achieve both heat-resistant storage stability and cleaning performance by embedding and fixing resin fine particles on the surface of toner base particles. Furthermore, in Patent Document 3, the core mainly includes a crystalline resin, the shell is 15% by mass or more and 120% by mass or less with respect to the core, and the shell has a hemispherical protrusion having a step of 0.3 μm or more, Attempts to achieve both low-temperature fixability and cleanability. In Patent Document 4, a technique is known in which crystalline polyester is coated with a surface layer mainly composed of an amorphous polymer to achieve both low-temperature fixability and charging characteristics.

JP 2008-233430 A JP2012-58489A JP 2005-274964 A JP 2004-191927 A

  However, in the core-shell structure in which such shell particles are buried in the core particles (hereinafter sometimes referred to as capsule structure), the shell particles gradually settle inside, so that the core particle portion is on the surface. There is a problem that it is exposed and the performance deteriorates with time. Furthermore, in general, the shell particles need to use a resin having a high glass transition point in order to ensure heat-resistant storage stability and cleaning properties, which causes deterioration in low-temperature fixability. In addition, when the compatibility between the core resin and the shell resin is high, there is a problem that the core resin and the shell resin are compatible in the image after fixing, the glass transition point is lowered, and the image is tacky. .

The present invention was obtained as a result of intensive studies in view of the above problems, and is a toner for developing electrostatic images that can achieve both low-temperature fixing and anti-blocking properties and is excellent in high charging stability, high image quality, and environmental stability. Is to provide.
The most effective form for achieving both low-temperature fixing and anti-blocking properties is that the shell particles have a higher coverage (capsule efficiency) on the surface of the core particles applied to the low-temperature fixing, and are thinner and easier to stay on the core particle surfaces. Capsule structure.

  The present inventors have made extensive studies to solve the above problems, and in a toner containing at least a binder resin and a colorant, shell particles of 0.2 μm or less are adhered to the core portion in a state close to a single layer. The present inventors have found a method for forming a core-shell structure having a thin shell layer. Further, in order to specify the core-shell structure according to the present invention, the surface of the toner base particles treated with ultrasonic waves is observed with a scanning electron microscope (abbreviated as SEM), and the occupancy ratio of the projected area of the shell particles to the projected area of the core particles is determined. By measuring and tracking the adhesion area ratio of the shell particles, the optimum correlation between the core-shell structure and the toner performance was found.

The present invention is based on this finding, and the gist of the present invention is as follows.
<1> A toner having toner base particles containing at least a binder resin and a colorant and an external additive, wherein the toner base particles have a core-shell structure having core particles and shell particles. A toner for developing an electrostatic charge image, wherein after the treatment, the ratio of the projected area of the shell particles to the projected area of the core particles is 25% or more and 60% or less.
<2> The toner for developing an electrostatic charge image according to <1>, wherein the shell particles have charge control performance.
<3> The electrostatic image developing toner according to <1> or <2>, wherein the shell particles are resin fine particles.
<4> The toner for developing an electrostatic charge image according to any one of <1> to <3>, wherein the shell particles have a volume average particle diameter of 50 nm to 150 nm.
<5> The electrostatic charge image development according to any one of <1> to <4>, wherein the content of the shell particles in the toner is 10 wt% or less with respect to the toner base particles. toner.
<6> The toner for developing an electrostatic charge image according to <3>, wherein the resin glass transition temperature (Tg) of the shell particles is equal to or higher than the glass transition temperature (Tg) of the binder resin of the toner base particles. . <7> The toner for developing an electrostatic charge image according to <3> or <6>, wherein the shell particles have a quaternary ammonium salt and a tertiary amine functional group, and have positive chargeability. <8> The electrostatic charge image developing toner according to any one of <3>, <6>, and <7>, wherein the shell particles are obtained by an emulsion polymerization method. The electrostatic charge image developing toner according to any one of <1> to <8>, wherein the particles are obtained by a polymerization method. <10> The shell particles are dispersed in the core particle dispersion. The electrostatic charge image development according to any one of <1> to <9>, wherein the toner base particles are obtained through a wet capsule process in which a liquid is mixed and attached to the surface of the core particles. Toner.

According to the present invention, it is possible to provide a toner for developing an electrostatic charge image that can achieve both low-temperature fixing and anti-blocking property, and is excellent in high charging stability, high image quality, and environmental stability of image quality.
This effect is obtained by adhering to the surface of the core particle having low temperature fixability with high adhesion strength and high coverage by the shell particle having strong chargeability and blocking resistance. With this new core-shell structure, more effective low-temperature fixing properties are realized, and at the same time, charging stability and excellent environmental resistance are exhibited.

3 is an image of an SEM photograph of toner base particles of the present invention. 3 is an image of an SEM photograph of the surface of toner base particles of the present invention. 3 is an image of an SEM photograph of the toner surface after ultrasonic treatment of the toner of the present invention.

In the present invention, the state before having the shell particles is referred to as a core particle, the one having a core-shell structure before having an external additive (in the capsule structure state) is referred to as a toner base particle, and the surface of the toner base particle. A toner having an external additive is called toner.
The toner of the present invention contains at least a binder resin and a colorant, and may contain a wax, a charge control agent, and the like as necessary. The core particles of the present invention are produced by a pulverization method or a wet polymerization method.

<1. Core particle>
The pulverization method can be obtained through a step of melt-kneading a binder resin, a colorant, a wax and the like at a high temperature, a pulverization step, and a classification step.
Examples of the wet polymerization method include a suspension polymerization method, an emulsion polymerization aggregation method, and a melt suspension method.

The suspension polymerization method is usually obtained by dissolving a colorant and wax in a binder resin monomer, and then suspending the monomer solution as monomer droplets in an aqueous medium by mechanical shearing force and performing polymerization. .
As the emulsion polymerization aggregation method, the polymer primary monomer is usually obtained by emulsifying the polymerizable monomer of the binder resin in an aqueous medium containing a polymerization initiator and an emulsifier, and polymerizing the polymerizable monomer with stirring. In this method, toner particles are produced by obtaining particles, adding a colorant and, if necessary, a charge control agent to aggregate the polymer primary particles, and aging the resulting aggregated particles.

The melt suspension method is usually obtained by dissolving a binder resin, wax or the like in a solvent to obtain an oil phase, suspending the oil phase as oil droplets in an aqueous medium, and then removing the solvent. It is done.
Among the wet polymerization methods, the emulsion polymerization aggregation method is preferable from the viewpoint of easy control of physical properties such as toner particle size and shape.
In the present invention, as a monomer component used for producing a binder resin, a monomer conventionally used in producing a binder resin for a toner can be appropriately used.

For example, a polymerizable monomer having an acidic group (hereinafter sometimes simply referred to as an acidic monomer), a polymerizable monomer having a basic group (hereinafter simply referred to as a basic monomer). ), Any polymerizable monomer having no acidic group or basic group (hereinafter sometimes referred to as other monomer) can be used.

  As the acidic monomer, a polymerizable monomer having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, cinnamic acid, a polymerizable monomer having a sulfonic acid group such as sulfonated styrene, Examples thereof include polymerizable monomers having a sulfonamide group such as vinylbenzenesulfonamide. Examples of the basic monomer include aromatic vinyl compounds having an amino group such as aminostyrene, nitrogen-containing heterocyclic-containing polymerizable monomers such as vinylpyridine and vinylpyrrolidone, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, etc. And (meth) acrylic acid ester having an amino group. These acidic monomer and basic monomer, together with the radical monomer used in the present invention, in the process of producing toner mother particles by suspension polymerization, emulsion polymerization aggregation, melt suspension, etc. Contributes to the stabilization of particles in water. It may be used singly or as a mixture of plural kinds, and may exist as a salt with a counter ion.

  Examples of the polymerizable monomer constituting the binder resin include styrenes such as styrene, methylstyrene, chlorostyrene, dichlorostyrene, p-tert-butylstyrene, pn-butylstyrene, and pn-nonylstyrene, Acrylic esters such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate , Methacrylates such as n-butyl methacrylate, isobutyl methacrylate, hydroxyethyl methacrylate, 2-ethylhexyl methacrylate, acrylamide, N-propylacrylamide, N, N-dimethylacrylamide, N, N-dipropyl Acrylamide, N, N-dibutyl acrylamide, and the like, the polymerizable monomer may be used singly, or may be used in combination.

  Furthermore, when the binder resin is a cross-linked resin, a polyfunctional monomer having radical polymerizability is used together with the above polymerizable monomer, for example, divinylbenzene, hexanediol diacrylate, ethylene glycol dimethacrylate, Diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, hexaethylene glycol dimethacrylate, nonaethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, Examples include diallyl phthalate. It is also possible to use a polymerizable monomer having a reactive group in a pendant group, such as glycidyl methacrylate, methylol acrylamide, acrolein and the like. Among these, radically polymerizable bifunctional polymerizable monomers are preferable, and divinylbenzene and hexanediol diacrylate are particularly preferable. These polyfunctional polymerizable monomers may be used alone or as a mixture of plural kinds.

  The binder resin has a number average molecular weight in gel permeation chromatography (hereinafter referred to as GPC) of preferably 2000 or more, more preferably 2500 or more, still more preferably 3000 or more, and preferably 50,000 or less. Preferably it is 40,000 or less, more preferably 35,000 or less. The weight average molecular weight determined in the same manner is preferably 30,000 or more, more preferably 40,000 or more, further preferably 50,000 or more, preferably 2 million or less, more preferably 1 million or less, and still more preferably It is desirable that it is 500,000 or less. When the number average molecular weight and the weight average molecular weight of the binder resin are in the above ranges, it is preferable because the durability, storage stability, and fixability of the toner are improved.

In the polymerization of the binder resin, known polymerization initiators can be used alone or in combination of two or more as required. For example, persulfates such as potassium persulfate, sodium persulfate, ammonium persulfate, and the like, and redox initiators combining these persulfates as a component with a reducing agent such as acidic sodium sulfite, hydrogen peroxide, 4,4 Water-soluble polymerization initiators such as' -azobiscyanovaleric acid, t-butyl hydroperoxide, cumene hydropeoxide, etc., and these water-soluble polymerization initiators as a component combined with a reducing agent such as ferrous salt Redox initiator systems, benzoyl peroxide, 2,2′-azobis-isobutyronitrile, and the like are used. These polymerization initiators may be added to the polymerization system before, simultaneously with the addition of the monomer, or after the addition, and these addition methods may be combined as necessary.

  In the present invention, a known chain transfer agent can be used as necessary. Specific examples of the chain transfer agent include t-dodecyl mercaptan, 2-mercaptoethanol, diisopropyl xanthogen, carbon tetrachloride, trichlorobromomethane, and the like. The chain transfer agent may be used alone or in combination of two or more, and is used in an amount of 0 to 5% by weight based on the polymerizable monomer.

  Moreover, in this invention, a well-known suspension stabilizer can be used as needed. Specific examples of the suspension stabilizer include calcium phosphate, magnesium phosphate calcium hydroxide, magnesium hydroxide and the like. These may be used alone or in combination of two or more, and may be used in an amount of 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer.

Both the polymerization initiator and the suspension stabilizer may be added to the polymerization system at any time before, simultaneously with, or after the addition of the polymerizable monomer. You may combine.
In addition, a pH adjuster, a polymerization degree adjuster, an antifoaming agent, and the like can be appropriately added to the reaction system.

In the present invention, when the binder resin is polymerized by an emulsion polymerization method, known emulsifiers can be used, and are selected from cationic surfactants, anionic surfactants, and nonionic surfactants. One or two or more emulsifiers can be used in combination.
Examples of the cationic surfactant include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, hexadecyl trimethyl ammonium bromide, and examples of the anionic surfactant include And fatty acid soap such as sodium stearate and sodium dodecanoate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate and the like. Nonionic surfactants include, for example, polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monooleate ether, monodecanoyl sucrose, etc. Is mentioned.

  In this invention, it is preferable that the usage-amount of an emulsifier is used by 0.1 to 10 mass parts with respect to 100 mass parts of polymerizable monomers. In addition, these emulsifiers can be used as protective colloids, for example, one or more of partially or completely saponified polyvinyl alcohols such as polyvinyl alcohol and cellulose derivatives such as hydroxyethyl cellulose.

In the present invention, the volume average particle size of the polymer primary particles obtained by the emulsion polymerization method is usually 0.02 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, and usually 3 μm or less, preferably It is 2 μm or less, more preferably 1 μm or less. When the particle size is smaller than the above range, it may be difficult to control the aggregation rate in the aggregation step. When the particle size is larger than the above range, the particle size of the toner base particles obtained by aggregation tends to be large. It may be difficult to obtain a toner having a target particle size.

  In the toner of the present invention, a wax can be used as an anti-offset agent. In recent years, attempts have been made to improve the low-temperature fixability of toners, but low-temperature fixability, blocking resistance, and high-temperature offset resistance are usually in a trade-off relationship. The use of a wax as an inhibitor is preferred.

  As the wax used in the toner of the present invention, known waxes can be arbitrarily used. Specifically, olefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, copolymer polyethylene, paraffin wax, and behenyl behenate. , Ester waxes having a long chain aliphatic group such as montanic acid ester and stearyl stearate, plant waxes such as hydrogenated castor oil carnauba wax, ketones having a long chain alkyl group such as distearyl ketone, silicones having an alkyl group And higher fatty acids such as stearic acid, long-chain fatty acid alcohols, long-chain fatty acid polyhydric alcohols such as pentaerythritol, and partial ester forms thereof, higher fatty acid amides such as oleic acid amide and stearic acid amide, etc. Paraffin wax The hydrocarbons such as Fischer-Tropsch wax, ester wax, and silicone waxes.

  In the present invention, the wax may be used alone or in combination. In order to improve fixability among these waxes, the melting point is preferably 120 ° C. or lower, more preferably 110 ° C. or lower, and particularly preferably 100 ° C. or lower. As a minimum of melting | fusing point, 40 degreeC or more is preferable, More preferably, it is 50 degreeC or more. If the melting point is too high, the effect of reducing the fixing temperature may be poor, and if the melting point is too low, problems may occur in the caking property and storage stability.

  In the present invention, the amount of the wax is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 5 parts by mass or more based on 100 parts by mass of the toner. Moreover, it is preferable that it is 40 mass parts or less, More preferably, it is 35 mass parts or less, More preferably, it is 30 mass parts or less. If the wax content in the toner is too low, performance such as high-temperature offset may not be sufficient. If it is too high, the anti-blocking property may be insufficient or the wax may leak from the toner and contaminate the device. There is a case.

In the present invention, as a method of blending the wax in the polymerization method, it is preferable to previously disperse the wax in water to a volume average particle size of 0.01 μm or more and 2.0 μm or less. Furthermore, it is preferable that it is 1.0 micrometer or less, and it is especially preferable that it is 0.5 micrometer or less.
Furthermore, in the emulsion polymerization aggregation method, it is preferable to add the wax dispersion dispersed in the above average particle diameter range during the emulsion polymerization or in the aggregation step.

In order to disperse the wax with a suitable dispersed particle size in the toner, it is preferable to use so-called seed polymerization in which the wax is added as a seed during emulsion polymerization. By adding as a seed, the wax is finely and uniformly dispersed in the toner, so that deterioration of the chargeability and heat resistance of the toner can be suppressed.
In addition, a wax / long-chain polymerizable monomer dispersion obtained by previously dispersing a wax in a water-based dispersion medium with a long-chain polymerizable monomer such as stearyl acrylate is prepared in advance. The polymerizable monomer can also be polymerized in the presence of the body.

A known colorant can be arbitrarily used as the colorant contained in the present invention. Specific examples of colorants include carbon black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow, rhodamine dyes, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane dye, monoazo, Any known dyes and pigments such as disazo dyes and condensed azo dyes can be used alone or in combination. In the case of a full-color toner, it is preferable to use benzidine yellow for yellow, monoazo and condensed azo dyes, magenta for quinacridone and monoazo dyes, and cyan for phthalocyanine blue. The colorant is preferably used so as to be 3 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polymer primary particles.

  The blending of the colorant in the emulsion polymerization aggregation method is usually performed in an aggregation step. A dispersion of polymer primary particles and a dispersion of colorant particles are mixed to form a mixed dispersion, which is then aggregated to form a particle aggregate. The colorant is preferably used in a state of being dispersed in water in the presence of an emulsifier, and the volume average particle diameter of the colorant particles is 0.01 or more, more preferably 0.05 μm or more, and more preferably 3 μm or less. 1 μm.

The core particle of the present invention may be produced by any polymerization method such as a suspension polymerization method, an emulsion polymerization aggregation method, or a dissolution suspension method, and is not particularly limited.
In the present invention, as a method for producing a suspension polymerization toner, a coloring agent, a polymerization initiator, and, if necessary, a wax, a polar resin, a charge control agent, a crosslinking agent, etc. in the above-mentioned binder resin monomer. An additive is added to prepare a monomer composition that is uniformly dissolved or dispersed. This monomer composition is dispersed in an aqueous medium containing a dispersion stabilizer and the like. Preferably, granulation is performed by adjusting the stirring speed and time so that the droplets of the monomer composition have a desired toner particle size. Thereafter, polymerization is performed by stirring to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. These are collected by washing and filtration, and dried to obtain core particles. Next, as will be described later, toner base particles having a core-shell structure can be obtained through a step (capsule step) of coating the surface of the core particles with polymer primary particles as shell particles.

  As a production method of the emulsion polymerization aggregation method, a colorant dispersion, a wax dispersion, etc. are prepared, and emulsion polymerization is performed in the presence of polymer primary particles of a binder resin monomer obtained by emulsion polymerization or a wax dispersion. A method in which the polymer primary particles of the wax-containing binder resin monomer obtained by the above are mixed with a colorant dispersion, a wax dispersion, etc., and then agglomerated by heating and then a aging step And agglomeration by mixing with the polymer primary particles of the binder resin monomer obtained by emulsion polymerization in the presence of the colorant and the wax and the wax dispersion or the like and heating. After passing through the step of aging, mixing the polymer primary particles of the binder resin monomer obtained by emulsion polymerization in the presence of a colorant and wax, a wax dispersion, etc., and heating By doing etc. After a collecting to step include a method via an additional aging step. Core particles can be obtained by these methods. Next, as will be described later, toner base particles having a core-shell structure can be obtained through a step (capsule step) of coating the surface of the core particles with polymer primary particles as shell particles. Among the production methods of the emulsion polymerization aggregation method described above, when the binder resin monomer is polymerized in the presence of the colorant, the metal in the colorant affects radical polymerization, making it difficult to control the molecular weight and rheology of the resin. Therefore, the emulsion polymerization aggregation method in which the colorant is not added during emulsion polymerization and the colorant dispersion is added in the aggregation step is preferable.

  In the present invention, in the aggregation step in the emulsion polymerization aggregation method, the polymer primary particles, the colorant particles, and if necessary, the charge control agent, the compounding component such as wax are mixed simultaneously or sequentially, Of the above components, that is, a polymer primary particle dispersion, a colorant particle dispersion, a charge control agent dispersion, and a wax fine particle dispersion, if necessary, are mixed to obtain a mixed dispersion. It is preferable from the viewpoint of the uniformity of the composition and the uniformity of the particle diameter.

In the emulsion polymerization aggregation method, the aggregation is usually carried out in a tank equipped with a stirrer, but there are a heating method, a method of adding an electrolyte, and a method of combining them. When polymer primary particles are agglomerated with stirring to obtain particle aggregates of the desired size, the particle size of the particle aggregates is controlled based on the balance between the agglomeration force between the particles and the shearing force due to agitation. However, the cohesive force can be increased by heating or adding an electrolyte.

In the present invention, the electrolyte in the case where the electrolyte is added and agglomerated may be any of acid, alkali and salt, and may be any of organic and inorganic. Specifically, the acid may be hydrochloric acid, Nitric acid, sulfuric acid, citric acid, etc., as alkali, sodium hydroxide, potassium hydroxide, aqueous ammonia, etc., as salt, NaCl, KCl, LiCl, Na ₂ SO ₄ , K ₂ SO ₄ , Li ₂ SO ₄ , MgCl ₂ , _{CaCl 2, MgSO 4, CaSO 4} , ZnSO 4, Al 2 (SO 4) 3, Fe 2 (SO 4) 3, CH 3 COONa, C 6 H 5 SO 3 Na and the like. Of these,
Inorganic salts having a divalent or higher polyvalent metal cation are preferred.

  In the present invention, the amount of electrolyte added varies depending on the type of electrolyte, target particle size, etc., but is preferably 0.02 parts by mass or more, based on 100 parts by mass of the solid component of the mixed dispersion, and 0.05 parts by mass. Part or more is more preferable. Further, it is preferably 25 parts by mass or less, more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. If the amount added is too small, the progress of the agglutination reaction will be slow, and there will be problems such as fine powder of 1 μm or less remaining after the agglomeration reaction, or the average particle size of the obtained particle aggregate will not reach the target particle size. If the amount is too large, rapid aggregation tends to occur, making it difficult to control the particle diameter, and the resulting aggregated particles may include problems such as coarse powders and irregular shapes. When the aggregation is performed by adding an electrolyte, the aggregation temperature is 20 ° C. or higher, more preferably 30 ° C. or higher, 80 ° C. or lower, more preferably 70 ° C. or lower.

The time required for agglomeration is optimized depending on the shape of the apparatus and the processing scale, but in order for the toner particle size to reach the target particle size, it is usually held at the predetermined temperature for at least 30 minutes. desirable. The temperature rise until reaching the predetermined temperature may be raised at a constant rate, or may be raised stepwise.
In the present invention, if necessary, particles having resin fine particles attached or fixed thereto can be formed on the surface of the particle aggregate after the above-described aggregation treatment. By attaching or fixing resin fine particles whose properties are controlled to the surface of the particle aggregate, the chargeability and heat resistance of the obtained toner may be improved, and the effects of the present invention can be further enhanced. .

  When resin fine particles having a glass transition temperature higher than the glass transition temperature of the polymer primary particles are used as the resin fine particles, it is preferable because blocking resistance can be further improved without impairing fixability. The volume average particle size of the resin fine particles is preferably 0.02 μm or more, and more preferably 0.05 μm or more. Moreover, 3 micrometers or less, Furthermore, 1.5 micrometers or less are preferable. As the resin fine particles, those obtained by emulsion polymerization of monomers similar to the polymerizable monomers used for the above-described polymer primary particles can be used.

The resin fine particles are usually used as a dispersion dispersed in water or a liquid mainly composed of water using a surfactant. However, when a charge control agent is added after the aggregation treatment, charge control is performed on the dispersion containing particle aggregates. It is preferable to add resin fine particles after adding the agent.
In order to increase the stability of the particle aggregate obtained in the aggregation step, it is preferable to perform fusion in the aggregated particles in the aging step after the aggregation step. The temperature of the ripening step is preferably not less than Tg of the polymer primary particles, more preferably not less than 5 ° C higher than Tg, and preferably not more than 80 ° C higher than Tg, more preferably not less than 50 ° C higher than Tg. It is as follows. The time required for the aging step varies depending on the shape of the target toner, but after reaching the glass transition temperature or higher of the polymer primary particles, it is usually held for 0.1 to 10 hours, preferably 1 to 6 hours. Is desirable.

In addition, it is preferable to add a surfactant, raise the pH value, or use the above methods in combination after the agglomeration step, preferably before the aging step or during the aging step. As the surfactant used here, one or more emulsifiers can be selected from the emulsifiers that can be used when producing the polymer primary particles. In particular, the emulsifiers used when producing the polymer primary particles. It is preferable to use the same. The addition amount in the case of adding the surfactant is not limited, but is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and preferably with respect to 100 parts by mass of the solid component of the mixed dispersion. Is 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 10 parts by mass or less. After the aggregation process, before the completion of the ripening process, by adding a surfactant or raising the pH value, it is possible to suppress aggregation of the particle aggregates aggregated in the aggregation process, In some cases, the generation of coarse particles can be suppressed.

  By heat treatment in the aging step, the polymer primary particles in the aggregate are fused and integrated, and the toner particle shape as the aggregate becomes close to a spherical shape. The particle aggregate before the aging step is considered to be an aggregate due to electrostatic or physical aggregation of the polymer primary particles, but after the aging step, the polymer primary particles constituting the particle aggregate are fused to each other. In addition, the shape of the toner particles can be made nearly spherical. According to such an aging process, by controlling the temperature and time of the aging process, the shape of the polymer primary particles is agglomerated, a potato type with advanced fusion, a spherical form with further fusion For example, various shapes of toner can be manufactured according to the purpose.

<2. Shell particles>
In the present invention, the shell particles to be coated on the surface of the core particles may be inorganic particles or resinous particles, and are not particularly limited. From the viewpoints of particle production, controllability of particle performance, and improvement of fixing strength when fixing toner, the shell particles are preferably resin particles.
When the shell particles are resin fine particles, the resin component is not particularly specified, but for example, a resin used in a general toner binder resin such as a styrene type, an acrylic type or an ester type, or a copolymer type or a blend type thereof may be used. These resinous shell particles can be directly emulsified from a resin, or can be prepared by a polymerization method such as emulsion polymerization or suspension polymerization. A polymerization method is desirable from the viewpoint of particle size control and ease of atomization, and an emulsion polymerization method is more preferable from the viewpoint of particle size and particle size distribution control of the fine particles.

When the resinous shell particles are prepared by the emulsion polymerization method, they can be prepared by the same emulsion polymerization method as the primary particles of the binder resin monomer polymer used in the emulsion polymerization aggregation method.
The volume average particle size of the resinous shell particles is not particularly limited as long as the effects of the present invention are not impaired, but is preferably 20 nm or more, and more preferably 50 nm or more. Moreover, 500 nm or less, Furthermore 150 nm or less are preferable.

The weight average molecular weight of the resinous shell particles is preferably 2,000 to 30,000, more preferably 4,000 to 25,000, and particularly preferably 6,000 to 20,000.
The glass transition temperature of the resinous shell particles is not particularly limited as long as the effect of the present invention is not impaired, but the lower limit is preferably 40 ° C. or higher, more preferably 45 ° C. or higher, while the upper limit is Preferably, it is 100 degrees C or less, More preferably, it is 80 degrees C or less, More preferably, it is 75 degrees C or less.

  From the viewpoint of enhancing the blocking resistance effect, the glass transition temperature (Tg) of the resinous shell particles is preferably higher than the glass transition temperature (Tg) of the binder resin of the core particles. At this time, the glass transition temperature (Tg) of the resinous shell particles is preferably (the glass transition temperature (Tg) of the core particles or higher, more preferably (the glass transition temperature of the core particles (Tg) +2) ° C. or higher. (Glass transition temperature of core particle (Tg) +5) ° C. or more is more preferable, On the other hand, (Glass transition temperature of core particle (Tg) +50) ° C. or less is preferable, (Glass transition temperature of core particle (Tg) +30) ° C. The following is more preferable, and (core glass transition temperature (Tg) +20) ° C. or lower is further preferable.

If the weight average molecular weight of the resinous shell particles and the glass transition temperature are too low, the toner may have poor blocking resistance. On the other hand, if it is too high, the low-temperature fixability may deteriorate.
The content of the shell particles is not particularly limited as long as the effect of the present invention is not impaired with respect to the toner base particles, but the lower limit is usually 0.01 wt% or more, preferably 0.3 wt% or more, On the other hand, the upper limit is usually 10 wt% or less.

The shell particles may be either non-chargeable or chargeable depending on the purpose of use. When the shell particles are chargeable, they have positive chargeability or negative chargeability.
In the toner of the core-shell structure of the present invention, the chargeability of the toner can be controlled by using chargeable shell particles in addition to the compatibility between low-temperature fixability and blocking resistance.
The chargeability of the toner is generally adjusted by a charge control agent, a binder resin, or an external additive, and an inorganic charge control agent is generally used as the charge control agent. Research has been conducted on the use of functional resins (charge control resins) as charge control agents, or by introducing various functional groups into the binder resin and using these properties to improve chargeability. It was. For example, in the case of a positively charged toner, it is common to impart chargeability by copolymerizing a monomer containing an amino group or an amide bond with a binder resin.

  As a method of using the charge control agent, generally, a charge control agent is dispersed in a toner binder resin, or a polymerizable monomer having a charge control ability (hereinafter sometimes referred to as a charge control resin) is used. There is a method of copolymerizing with a binder resin and dispersing in the binder resin. However, if the dispersion of the charge control agent or charge control resin in the toner base particles or on the toner base particle surface is non-uniform, it will lead to problems such as increased fog and toner scattering. In order to reduce the toner particle size, uniform dispersibility of the charge control agent and the charge control resin is more demanded. Generally, it is said that the chargeability of the toner is controlled by the resin performance on the toner surface. When the charge control agent or charge control resin is uniformly dispersed in the toner binder resin, it is necessary to add more charge control agent or charge control resin in order to obtain a sufficient charge control effect. In addition, the low temperature fixability of the toner may be deteriorated by the charge control agent or the charge control resin.

  Therefore, it is desirable that a charge control agent and a charge control resin exist on the toner surface. Compared to the toner base particles obtained by the pulverization method, the toner base particles obtained by the polymerization method, especially the toner base particles obtained by the emulsion aggregation method, are mixed with a charge control agent or charge control resin during the production of the toner base particles. By controlling the timing, it is possible to control the position of the charge control agent or charge control resin in the toner, but it is difficult to completely expose the toner surface.

Therefore, in the present invention, when charging property is imparted to the toner base particles, the shell layer is charged by adding a charge control agent or charge control resin to the shell particles in order to effectively control the charging property of the toner. A core-shell structure with controllability is preferable.
When the shell particles are resinous fine particles, it is preferable to use resinous shell particles obtained by copolymerizing a resin used for the shell particles and a charge control resin.

If shell particles of positively chargeable resin particles, as the positive charge control _{resin, -NH 2, -NHCH 3, -N} (CH 3) 2, -NHC 2 H 5, -N (C 2 Resins containing amino groups such as H ₅ ) ₂ , —NHC ₂ H ₄ OH; resins containing quaternary ammonium salts in which they are ammonium chlorided. Among these, a resin containing a quaternary ammonium salt is preferable.

Such a charge control resin exhibiting positive chargeability can be obtained, for example, by copolymerizing a monovinyl monomer containing an amino group and a monomer copolymerizable therewith. The positively chargeable charge control resin can also be obtained by ammonium-treating a copolymer containing an amino group. A resin containing a quaternary ammonium salt can also be obtained by copolymerizing a monovinyl monomer containing an ammonium salt group and a monovinyl monomer copolymerizable therewith. However, the method for producing the positively chargeable charge control resin is not limited to these methods. As a monomer to be copolymerized, a monomer generally used for a binder resin can be used.

  Among the resins containing a quaternary ammonium salt group as a positively chargeable charge control resin, an acrylate containing a quaternary ammonium salt represented by the following structural formula (1) and 4 represented by the following structural formula (2) Acrylamide containing a quaternary ammonium salt is preferred, and an acrylate containing a quaternary ammonium salt represented by the following structural formula (1) is more preferred.

In the above structural formulas (1) and (2), R ¹ is a hydrogen atom or a methyl group, R ² is an alkylene group, and R ³ , R ^4, and R ⁵ are each independently hydrogen. It is an atom or a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and X- is a halogen ion, a benzenesulfonate ion or an alkylbenzenesulfonate ion.

In the quaternary ammonium salt represented by the above structural formula (1), X- is preferably a chloride ion or a toluenesulfonate ion, R ¹ is preferably a hydrogen atom or a methyl group, and R ² Is preferably an alkylene group having 1 to 3 carbon atoms such as CH ₂ , C ₂ H ₄ , and C ₃ H ₆ and derivatives thereof, and R ^{3 to} R ⁵ are each independently CH ₃ , C ₂ H _5. And an alkyl group such as C ₃ H ₇ .

Examples of amino group-containing (meth) acrylate monomers include dimethylaminomethyl (meth) acrylate, diethylaminomethyl (meth) acrylate, dipropylaminomethyl (meth) acrylate, diisopropylaminomethyl (meth) acrylate, and ethylmethylamino. Methyl (meth) acrylate, methylpropylaminomethyl (meth) acrylate, dimethylamino-1-ethyl (meth) acrylate, diethylamino-1-ethyl (meth) acrylate, dipropylamino-1-ethyl (meth) acrylate, diisopropylamino -1-ethyl (meth) acrylate, ethylmethylamino-1-ethyl (meth) acrylate, methylpropylamino-1-ethyl (meth) acrylate, dimethylamino-2-ethyl (meth) Chlorate, diethylamino-2-ethyl (meth) acrylate, dipropylamino-2-ethyl (meth) acrylate, diisopropylamino-2-ethyl (meth) acrylate, ethylmethylamino-2-ethyl (meth) acrylate, methylpropylamino 2-ethyl (meth) acrylate, dimethylamino-1-propyl (meth) acrylate, diethylamino-1-propyl (meth) acrylate, dipropylamino-1-propyl (meth) acrylate, diisopropylamino-1-propyl (meth) ) Acrylate, ethylmethylamino-1-propyl (meth) acrylate, methylpropylamino-1-propyl (meth) acrylate, dimethylamino-2-propyl (meth) acrylate, diethylamino-2-propi (Meth) acrylate, dipropylamino-2-propyl (meth) acrylate, diisopropylamino-2-propyl (meth) acrylate, ethylmethylamino-2-propyl (meth) acrylate, methylpropylamino-2-propyl (meth) Examples include N, N-disubstituted aminoalkyl (meth) acrylate compounds such as acrylate.

Examples of the quaternizing agent used for converting the copolymer into an ammonium salt include alkyl halides such as methyl iodide, ethyl iodide, methyl bromide, and ethyl bromide; methyl paratoluenesulfonate, paratoluene And paratoluenesulfonic acid alkyl esters such as ethyl sulfonate and propyl paratoluenesulfonate.
Examples of commercially available quaternary ammonium base-containing (meth) acrylate monomers include Blemmer QA (manufactured by NOF Corporation).

  The amount of the chargeable monomer unit having a functional group such as an amino group and an ammonium base is preferably 0.5 to 15% by weight, more preferably 1 to 12% by weight, and particularly preferably 2 to 2% in the charge control resin. 10% by weight. If the amount of the monomer unit having the functional group is too small, a large amount of charge control resin is required to obtain a necessary charge amount, and the environmental stability of the toner tends to be lowered. When the amount of the monomer unit having the functional group is too large, the charge amount of the toner under high temperature and high humidity is greatly reduced, and fogging may occur.

Various commercially available products can be used as the positively chargeable charge control resin. For example, as manufactured by Fujikura Kasei Co., Ltd., FCA-161P (: trade name, styrene / acrylic resin), FCA-207P (: trade name, styrene / acrylic resin), and FCA-201-PS (: trade name, styrene / acrylic resin) Acrylic resin).
Any negative charge control resin can be used, including styrene-acrylic resins and polyester resins used in general negatively charged toners. A commercially available negative charge control resin can also be used.

The method for producing the resin charge controllable shell particles can be directly emulsified from the charge control resin, or can be prepared by a polymerization method such as emulsion polymerization or suspension polymerization. A polymerization method is desirable from the viewpoint of particle size control and ease of atomization, and an emulsion polymerization method is more preferable from the viewpoint of particle size and particle size distribution control of the fine particles.
When creating resinous shell particles by the emulsion polymerization method, create by copolymerizing with the chargeable monomer using the same production method as the primary particles of the binder resin monomer polymer used in the emulsion polymerization aggregation method. can do.

  When the charge control resin is used for shell particles, core particles, or toner base particles, the chargeable monomer is not particularly limited as long as it does not significantly impair the effects of the present invention. 0.01 wt% or more, and more preferably 0.05 wt% or more, more preferably 0.1 wt% or more in order to exhibit a charge control function, while the upper limit is usually 5 wt% or less. In order to prevent the influence of the charge control resin on the toner performance (especially environment resistance and fixing property), it is preferably 2 wt% or less, more preferably 1 wt% or less.

<3. Method for coating shell particles on core particles (capsule process)>
Hereinafter, the process of coating the core particles with the shell particles may be referred to as a capsule process. Control for coating the core particles with shell particles may be referred to as capsule control.
A method for producing a capsule toner having a core-shell structure includes a method of forming a capsule structure by mixing a shell particle component in the latter half of the process of forming a conventional core particle, and a method for producing toner base particles of the present invention. Aside from the core particle manufacturing process, there is a method of forming a capsule structure by a capsule process in which a shell layer is formed on the surface of a completed core particle.

  In the former case, which is a conventional embodiment, the core particles are being formed, and the surface of the core particles is not particularly stable, so that the shell particles are easily embedded in the core particle layer, and the shell particles are attached to the core particles. Strong, but on the other hand, the core particle component is more likely to come out on the surface of the toner base particle than the embedding of the shell particle on the surface of the core particle, and more in order to completely cover (capsule) the core particle with the shell particle. Shell particles are required.

  On the other hand, in the latter case, which is an embodiment for realizing the present invention, a shell structure is formed on the surface of the completed core particle by the shell particle encapsulating step separately from the core particle forming step. It is easy to stay and a uniform capsule structure can be formed with fewer shell particles. Since the capsule efficiency is high, exposure of the core particle component to the toner surface can be prevented.

  In the present invention, the charging polarity of the core particles and the charging polarity of the shell particles are set to be opposite to each other and are electrostatically attached. This electrostatic adhesion makes it easier for the shell particles to stay on the surface of the core particles, and it is possible to increase the adhesion efficiency (encapsulation efficiency) of the shell particles to the core particles. Can prevent exposure. Furthermore, due to the electrostatic repulsion effect between the shell particles, a uniform coating layer close to a single layer in which the shell particles do not overlap can be formed on the surface of the core particles with fewer shell particles. The thickness of the single-layer shell layer formed by electrostatic adhesion of the shell particles described above is the same as the volume average particle diameter of the shell particles, and is not particularly limited as long as the effect of the present invention is not significantly impaired. , 20 nm or more, preferably 50 nm or more, on the other hand, usually 500 nm or less, preferably 150 nm or less.

Further, a uniform double shell layer can be formed by forming a shell layer with shell particles having a certain charged polarity and then forming a shell layer with shell particles having a polarity opposite to that of the shell particles. By repeating this double shell layer formation, a uniform multiple shell layer can also be formed.
When a multi-shell layer is employed, the charge control of the toner base particles can be controlled by the charge polarity of the shell particles of the outermost surface layer.

  The step of covering the core particles with the shell particles (capsule step) is performed by directly adding and mixing the shell particles to the core particle dispersion. In the case of core particles obtained by a pulverization method, the dispersion of core particles can be a dispersion dispersed from an emulsifier, and in the case of core particles obtained by a polymerization method, the slurry liquid at the time of core particle production can be used as it is. . From the viewpoint of more precise capsule control, it is preferable to remove the emulsifier present in the core particle dispersion from a method such as washing within a range in which aggregates of core particles are not generated.

For example, when preparing a dispersion of the core particles obtained by the polymerization method, after removing the emulsifier and soluble impurities contained in water and water by dehydrating and dropping the slurry liquid at the time of core particle production from the polymerization method, By redispersing the obtained core particle cake in water, a core particle dispersion can be prepared.
Regarding the conditions of the capsule process, the mixing temperature of the core particles and the shell particles is not particularly limited. However, mixing at a temperature 10 ° C. lower than the lowest Tg among the Tg of the core particles and the shell particles is more rapid than the rapid aggregation. This is preferable because it can prevent the generation of aggregates and can uniformly mix the core particles and the shell particles. If uniform mixing is possible, in order to increase the capsule efficiency and capsule strength of the shell particles, it is possible to control by adding an aggregating agent such as an electrolyte and adjusting the mixing temperature as necessary.

  In order to control the capsule of the shell particles in the core particles, the electrolyte concentration or pH of the mixed solution can be adjusted. As the electrolyte, inorganic or organic acids, alkalis and salts can be used. It can be selected according to the polarity of a general shell particle dispersion. For example, when the polarity of the shell particle dispersion is anionic, an acidic electrolyte is preferable. When the polarity of the shell particle dispersion is cationic, an alkaline electrolyte is preferable. When the polarity of the shell particle dispersion is nonionic, any electrolyte is effective.

In order to increase the capsule efficiency and capsule strength of the shell particles, the mixing temperature can be controlled. When adjusting the temperature, in order to prevent embedding on the surface of the core particle of the shell particle, the mixing temperature is preferably Tg + 20 ° C. or less of the core particle.
Further, when the surface of the toner base particle having the core-shell structure according to the present invention obtained by utilizing electrostatic adhesion as described above was observed by SEM, as shown in FIG. 1 and FIG. It can be seen that the portion exposed from the core particle of the shell particle without being embedded in the surface of the core particle is attached to the surface of the core particle in a state where it is equal to or larger than the radius of the shell particle. The occupancy ratio of the projected area of the shell particles to the projected area of the core particles is usually 30% or more, and preferably 50% or more from the viewpoint of the compatibility between the storage stability of the toner and the low-temperature fixing performance. Due to electrostatic repulsion between each other, it is usually 90% or less.

  Therefore, in the present invention, after forming the core particles, as described above, the core particles and the shell particles having the oppositely charged polarity are mixed and the shell particles are electrostatically attached to the surface of the core particles. Thus, a core-shell structure can be formed with a high coverage (encapsulation efficiency) with a smaller amount of shell particles added. The shell layer with high encapsulation efficiency provides toner chargeability stably, improves toner blocking resistance, and the addition of the minimum amount of shell particles has an effect on the low-temperature fixability of the core particles. It was possible to achieve both the low-temperature fixability and the blocking resistance, which are the problems of the present invention, to the minimum.

<4. Cleaning and drying of toner base particles>
The toner base particles obtained by coating the core particles with the shell particles are separated from the aqueous solvent, washed, dried, and subjected to an external addition treatment as necessary to be used as a toner for developing an electrostatic image. .
Water is used as the liquid used for washing, but washing with an acid or alkali aqueous solution is also possible. Moreover, it can also wash | clean with warm water or hot water, and these methods can also be used together. Through such a washing step, the suspension stabilizer, the emulsifier, the unreacted residual monomer and the like can be reduced and removed, which is preferable. In the washing step, the liquid to be washed is subjected to, for example, filtration, decantation, etc., so that the colored particles are made into a thick slurry or wet cake, and the liquid for washing is newly added to this to disperse the toner base particles. It is preferable. The colored particles after washing are preferably collected in the form of a wet cake in terms of handling in the subsequent drying step.

In the drying process, a fluidized drying method such as a vibration type fluidized drying method or a circulation type fluidized drying method, an air flow drying method, a vacuum drying method, a freeze drying method, a spray drying method, a flash jet method, or the like is used. Operating conditions such as temperature, air volume, and degree of reduced pressure in the drying step are appropriately optimized based on the Tg of the colored particles, the shape, mechanism, size, etc. of the apparatus used.
The volume average particle size of the toner of the present invention is preferably 3 μm or more, and more preferably 5 μm or more. Moreover, 15 micrometers or less are preferable, and also 10 micrometers or less are more preferable. Further, the shape has an average circularity measured by using a flow type particle image analyzer FPIA-3000, preferably 0.90 or more, more preferably 0.92 or more, further preferably 0.94 or more, preferably Is 0.99 or less. If the average circularity is too small, it may cause a decrease in image density due to poor charging due to poor adhesion of the external additive to the colored particles. On the other hand, if it is too large, it may result in poor cleaning due to the colored particle shape. .

The glass transition point Tg by the DSC method of the toner of the present invention is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, preferably 80 ° C. or lower, more preferably 70 ° C. or lower. When Tg is in the above range, it is desirable because the storage stability and fixing property of the toner are improved.
<5. External Additive (External Additive Fine Particles)>
In the present invention, externally added fine particles other than the above-mentioned conductive fine particles can be added as necessary in order to improve the fluidity of the toner and charge control. Such external additive fine particles can be appropriately selected from various inorganic or organic fine particles.

  Inorganic fine particles include silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide, tungsten carbide, chromium carbide, molybdenum carbide, calcium carbide, and other carbides, boron nitride, titanium nitride. , Various nitrides such as zirconium nitride, various borides such as zirconium boride, various oxides such as titanium oxide, calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, cerium oxide, silica, colloidal silica, titanium Various titanate compounds such as calcium oxide, magnesium titanate and strontium titanate, phosphate compounds such as calcium phosphate, sulfides such as molybdenum disulfide, fluorides such as magnesium fluoride and fluorocarbon, aluminum stearate, stearin Calcium, zinc stearate, can be used various metal soaps such as magnesium stearate, talc, bentonite, various carbon black or conductive carbon black, magnetite, ferrite or the like. As the organic fine particles, fine particles such as styrene resin, acrylic resin, epoxy resin, and melamine resin can be used.

  Among these externally added fine particles, silica, titanium oxide, alumina, zinc oxide, various carbon blacks, conductive carbon blacks, and the like are preferably used. In addition, the externally added fine particles are formed on the surface of the inorganic or organic fine particles by using a silane coupling agent such as hexamethyldisilazane (HMDS) or dimethyldichlorosilane (DMDS), a titanate coupling agent, Silicone oil, dimethyl silicone oil, modified silicone oil, silicone oil treating agents such as amino-modified silicone oil, silicone varnish, fluorine-based silane coupling agent, fluorine-based silicone oil, coupling agent having amino group or quaternary ammonium base What has been subjected to surface treatment such as hydrophobization with a treating agent such as can also be used. Two or more kinds of the treatment agents can be used in combination.

In the toner of the present invention, it is preferable to add conductive fine particles as an external additive from the viewpoint of charge control. The upper limit of the resistance of the conductive fine particles is usually 400 Ω · cm or less, preferably 200 Ω · cm or less, more preferably 100 Ω · cm or less, and further preferably 60 Ω · cm or less. On the other hand, the lower limit is usually 0.1 Ω · cm or more, preferably 1 Ω · cm or more, more preferably 5 Ω · cm or more, and further preferably 15 Ω · cm. Examples of the conductive fine particles include metal oxides such as conductive titanium oxide, silica and magnetite, or those doped with a conductive substance, conjugated double bonds such as polyacetylene, polyphenylacetylene, and poly-p-phenylene. Examples include organic fine particles obtained by doping a conductive material such as metal to a polymer having carbon, carbon typified by carbon black and graphite, etc., but from the viewpoint that conductivity can be imparted without impairing the fluidity of the toner, conductive oxidation What doped titanium or its electroconductive substance is more preferable. The lower limit of the conductive fine particle content is usually 0.0 parts by mass or more, preferably 0.1 parts by mass or more, and 0.2 parts by mass with respect to 100 parts by mass of the toner base particles. More preferably. On the other hand, the upper limit of the content of the conductive fine particles is usually 3 parts by mass or less, preferably 2 parts by mass or less, and more preferably 1 part by mass or less.

In the present invention, when externally added fine particles other than conductive fine particles are used, the content of the externally added fine particles is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass with respect to 100 parts by mass of the toner base particles. It is at least 5 parts by mass, preferably at most 5 parts by mass, more preferably at most 4 parts by mass.
In the present invention, silica is further employed as an external additive used in combination with the conductive fine particles, and by selecting the type, amount and method of addition, toner performance, particularly toner chargeability, blocking resistance, Particle performance such as fluidity can be controlled. Further, when silica is employed, it is preferable to use two or more types of silica in combination in order to balance each performance.

In the present invention, the charging stability can be improved by having fine particles containing fluorine atoms on the surface of the toner base particles.
Furthermore, in the present invention, it is possible to mix silica with different charging polarities from the case in order to improve charging performance, other than using an external additive having the same charging polarity in accordance with the chargeability of the toner.

<6. External Addition Method of External Additive (External Additive Fine Particles)>
Examples of the method for adding the externally added fine particles include a method using a high-speed stirrer such as a Henschel mixer, a method using an apparatus capable of applying a compressive shear stress, and the like.
The external toner can be prepared by a one-step external addition method in which all external additives are added to the toner base particles at the same time for external addition, but can be prepared by a separate external addition method in which each external additive is externally added.
Regarding the temperature of external addition, in order to prevent temperature rise, it is preferable to install a cooling device in the container or perform external addition in stages.

<7. Projected area (coverage) of shell particles relative to the projected area of core particles>
The toner of the present invention is a toner having toner base particles containing at least a binder resin and a colorant and an external additive, and the toner base particles have a core-shell structure having core particles and shell particles, and the toner The ratio of the projected area of the shell particles to the projected area of the core particles is from 25% to 60% by ultrasonic treatment. The ratio of the projected area represents the coverage of the shell particles with respect to the core particles. The lower limit of the ratio of the projected area is 25% or more, and is preferably 30% or more, more preferably 40% or more, and still more preferably in order to further enhance the blocking resistance effect of the capsule layer of the shell particles. 45% or more. On the other hand, the upper limit is 60%.

In the present invention, the ratio of the projected area of the shell particles to the projected area of the core particles after ultrasonically treating the toner is determined by subtracting the toner for developing an electrostatic charge image obtained through the above-described external addition step into water. It is calculated by performing dispersion, ultrasonic processing, SEM observation, and image processing. Specifically, the toner for developing an electrostatic charge image is placed in a 1.2% aqueous solution of Triton X-100 (manufactured by Kishida Chemical) and dispersed in water with a stirrer (stirring blade R1311 turbine type stirring blade IKA Japan Co., Ltd.). Using a treatment device ultrasonic homogenizer (product name: VCX750 (Ieda Trading Co., Ltd.)) (standard probe type 630-0220), ultrasonic treatment of Energy 12KJ was performed at an amplitude of 37%. By this ultrasonic treatment, particles having low adhesion strength to the core particles, including the external additive on the surface of the toner for developing an electrostatic charge image, are removed.

Subsequently, an SEM image of the surface of the electrostatic image developing toner after the ultrasonic treatment was obtained in the same manner as described in Examples. Using the image processing program (WinROOF manufactured by MITANI) or (ImageProPlus manufactured by Media Cybernetics), median filter is applied to the SEM image to remove noise, flattening, and then adhere to the toner base particle surface. In order to make it easier to extract shell particles, the area ratio was measured by an automatic threshold method after changing the concentration using a lookup table. The total area ratio of the shell particles adhering to the core particle surface and the remaining external additive particles is measured by the analysis, and further, the shell particles adhering using the fact that the remaining external additive particles have a smaller diameter than the shell particles. In order to calculate the area ratio of only particles, the area ratio of particles having a diameter of 50 nm or more was measured.

  Through this series of treatments, it can be confirmed that the toner for developing an electrostatic charge image of the present invention, the shell particles adhere to or fuse with sufficient strength, and the core particles are shelled with high efficiency. It can be verified that the particles are coated.

<8. Other>
The toner for developing an electrostatic image of the present invention may be used in any form of a two-component developer using the toner together with a carrier or a magnetic or non-magnetic one-component developer not using a carrier. When used as a two-component developer, the carrier may be a magnetic substance such as iron powder, magnetite powder, ferrite powder or the like, or a known material such as a resin-coated surface or a magnetic carrier. As the coating resin of the resin coating carrier, generally known styrene resin, acrylic resin, styrene acrylic copolymer resin, silicone resin, modified silicone resin, fluororesin, or a mixture thereof can be used.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the following examples, “part” means “part by mass”. In addition, the live-action test was conducted by the following method.
Each particle diameter, circularity, electrical conductivity, thermal characteristics and the like were measured as follows.

<Medium diameter measurement (D50)>
The median diameter (D50) of particles with a median diameter of less than 1 micron (D50) is measured using Nikkiso Co., Ltd. model MicrotracNanotrac150 (hereinafter abbreviated as Nanotrack) and the company's analysis software MicrotracParticle Analyzer Ver10.1.2-019EE. Measured by the method described in the instruction manual under the measurement conditions of solvent refractive index: 1.333, measurement time: 600 seconds, number of measurements: 1 time, using ion-exchanged water having an electric conductivity of 0.5 μS / cm as a solvent. did. Other setting conditions were particle refractive index: 1.59, transparency: transmission, shape: true sphere, density: 1.04.

<Volume median particle size measurement (Dv50)>
For the volume median particle size (Dv50) of the particles having a volume median particle size (Dv50) of 1 micron or more, a multisizer III (aperture diameter 100 μm: hereinafter abbreviated as multisizer) manufactured by Beckman Coulter, It was measured by isoton II as a dispersion medium and dispersed to a dispersoid concentration of 0.03%.

<Average circularity measurement>
The average circularity is determined by dispersing the dispersoid in a dispersion medium (Cell Sheath: Sysmex) at 5720-7140 / μl, and using a flow particle analyzer (FPIA 3000: Sysmex) to analyze the amount of HPF. It measured by HPF mode on 0.35 microliters and HPF detection amount 2000-2500 conditions.

<Electrical conductivity measurement>
The electrical conductivity was measured using a conductivity meter (CyberScanCON100 manufactured by AS ONE Corporation).
<Weight average molecular weight (Mw)>
The THF-soluble component of the polymer primary particle dispersion was measured by gel permeation chromatography (GPC) under the following conditions.
Apparatus: GPC apparatus HLC-8020 manufactured by Tosoh Corporation, column: PL-gel Mixed-B 10μ manufactured by Polymer Laboratory, solvent: THF, sample concentration: 0.1% by weight, calibration curve: standard polystyrene

<Measuring method of glass transition temperature (Tg)>
Using a differential thermal analyzer (DSC200) manufactured by Seiko Denshi Kogyo Co., Ltd., the temperature was measured at a temperature rising rate of 10 ° C./min. The glass transition temperature was determined from the intersection of the base line extension of the DSC curve and the tangent line showing the maximum slope in the endothermic curve.

[Example 1]
<Adjustment of colorant dispersion>
Carbon black (Mitsubishi Chemical Corporation, Mitsubishi Carbon Black MA100S manufactured by Mitsubishi Chemical Co., Ltd.) manufactured by a furnace method in which a toluene extract has an ultraviolet absorbance of 0.02 and a true density of 1.8 g / cm 3 is placed in a stirrer vessel equipped with a propeller blade. ) 20 parts, 1 part of anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen S-20A), 4 parts of nonionic surfactant (Eugengen 120, manufactured by Kao Corporation), ion exchange with 2 μS / cm conductivity 75 parts of water was added and predispersed to obtain a pigment premix solution. The volume cumulative 50% diameter Dv50 of carbon black in the dispersion after premixing was about 90 μm. The premix solution was supplied as a raw material slurry to a wet bead mill and subjected to one-pass dispersion. In addition, the inner diameter of the stator was 120 mmφ, the separator diameter was 60 mmφ, and zirconia beads having a diameter of 50 μm (true density of 6.0 g / cm 3) were used as a dispersion medium. The effective internal volume of the stator is about 2 liters, and the media filling volume is 1
. Since it is 4 liters, the media filling rate is 70%. When the rotational speed of the rotor is constant (the peripheral speed at the tip of the rotor is about 11 m / sec), the premix slurry is supplied from the supply port by a non-pulsating metering pump at a supply speed of about 40 liters / hr, and reaches a predetermined particle size. The product was acquired from the outlet. During operation, cooling water at about 10 ° C. was circulated from the jacket to obtain a colorant dispersion.

<Preparation of wax dispersion A1>
Paraffin wax (Nippon Seiwa Co., Ltd., HNP-9, melting point 82 ° C.) 100 parts, stearyl acrylate 10.4 parts, 20% sodium dodecylbenzenesulfonate aqueous solution (Daiichi Kogyo Seiyaku Co., Ltd., Neogen S20D, 20% below) 7.0 parts (abbreviated as DBS aqueous solution) and 253.0 parts of demineralized water were heated to 90 ° C. and stirred for 10 minutes using a homomixer (Mark IIf model, manufactured by Tokushu Kika Kogyo Co., Ltd.). Next, under heating at 90 ° C., circulating emulsification is started using a high-pressure emulsifier under a pressure of 20 MPa, the particle diameter is measured with Nanotrac, and dispersed and emulsified until the median diameter (D50) is 500 nm or less. Liquid A2 was prepared. The median diameter (D50) was 250 nm.

<Preparation of polymer primary particle dispersion B1>
A reactor equipped with a stirrer (three blades), a heating / cooling device, a concentrating device, and a raw material / auxiliary charging device was charged with 35.7 parts of wax dispersion A1 and 259 parts of demineralized water, and a nitrogen stream was stirred. The temperature was raised to 90 ° C.
Thereafter, the following mixture of monomers and emulsifier solution was added over 300 minutes while stirring was continued. The time when the dropping of the mixture of the monomers and the aqueous emulsifier solution was started as polymerization initiation, the following aqueous initiator solution 1 was added over 270 minutes after the initiation of polymerization, and the aqueous initiator solution 2 was further added over 60 minutes. Thereafter, the inner temperature was maintained at 90 ° C. for 1 hour under stirring.

[Monomers]
Styrene 67.8 parts Butyl acrylate 32.2 parts Acrylic acid 1.2 parts Trichlorobromomethane 1.0 part Hexanediol diacrylate 0.9 part [Emulsifier aqueous solution]
20% DBS aqueous solution 1.0 part demineralized water 67.1 parts [initiator aqueous solution 1]
8% aqueous hydrogen peroxide solution 15.5 parts 8% L-(+) ascorbic acid aqueous solution 15.5 parts [initiator aqueous solution 2]
8% L-(+) ascorbic acid aqueous solution 14.2 parts After the completion of the polymerization reaction, the mixture was cooled to obtain a milky white primary polymer particle dispersion B1. The median diameter (D50) measured using a nanotrack was 267 nm. The weight average molecular weight (Mw) was 65000. The glass transition temperature (Tg) measured using DSC was 38 ° C.

<Preparation of polymer primary particle dispersion C1>
In a reactor equipped with a stirrer (3 blades), heating / cooling device, concentrating device, and raw material / auxiliary charging device, 0.6 part of Sanisol B-50 (Kao, concentration 50%), 335 parts of demineralized water Was heated to 70 ° C. under a nitrogen stream while stirring.
Thereafter, the initiator aqueous solution 1 was added while stirring was continued, and further 5 minutes later, the following mixed emulsion of monomers 1 and emulsifier solution and monomers 2 were added over 200 minutes. The time when the dropping of the mixture of the monomers and the aqueous emulsifier solution was started was set as the polymerization start, and the following aqueous initiator solution 2 was simultaneously added over 200 minutes. Further, the initiator aqueous solution 3 was further added over 60 minutes, and the temperature was raised to 90 ° C. simultaneously with the addition. After the initiator aqueous solution 3 was added, the inner temperature was maintained at 90 ° C. for 1 hour under stirring.

[Monomers 1]
Styrene 74.5 parts Butyl acrylate 25.5 parts [Emulsifier aqueous solution]
SANISOL B-50 (manufactured by Kao, concentration 50%) 0.6 parts demineralized water 71.8 parts [Monomers 2]
Bremer QA (manufactured by NOF 50% solution) 10.0 parts [Initiator aqueous solution 1]
8.0% 2,2′-azobis (2-methylpropionamidine) dihydrochloride (manufactured by Wako) aqueous solution 3.2 parts [initiator aqueous solution 2]
8.0% 2,2′-azobis (2-methylpropionamidine) dihydrochloride (manufactured by Wako) aqueous solution 10.5 parts [initiator aqueous solution 3]
8.0% aqueous solution of 2,2′-azobis (2-methylpropionamidine) dihydrochloride (manufactured by Wako) 3.2 parts After completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer primary particle dispersion C1. The median diameter (D50) measured using a nanotrack was 93 nm. The glass transition temperature (Tg) measured using DSC was 56 ° C.

<Production of Toner Base Particle D1-1>
At room temperature (about 25 ° C.), 100 parts of polymer primary particle dispersion B1 (solid content) in a mixer equipped with a stirrer (double helical blade), heating / cooling device, concentrating device, and each raw material / auxiliary charging device After adding 6.0 parts (solid content) of colored dispersion over 5 minutes and mixing uniformly, 0.3 part (solid content) of 0.5% aluminum sulfate solution was added dropwise. The temperature was further increased to 45 ° C. over 90 minutes. Here, the volume median particle size (Dv50) was measured using a multisizer, and when the particle size exceeded the target particle size of 8 microns, 4.0 parts (solid content) of 20% DBS aqueous solution was added, and then 60 The temperature was raised to 97 ° C over a period of 70 minutes and held for 70 minutes.

  Thereafter, the slurry obtained by cooling to 30 ° C. over 20 minutes was extracted, and suction filtered with an aspirator using 5 types C (No. 5C, manufactured by Toyo Roshi Kaisha, Ltd.). The cake remaining on the filter paper is transferred to a stainless steel container equipped with a stirrer (propeller blade), and ion-exchanged water having an electric conductivity of 1 μS / cm is added and dispersed uniformly by stirring at 50 rpm, and then stirred for 30 minutes. It was.

  After that, again using 5 kinds C filter paper and suction filtration with an aspirator, the solid matter remaining on the filter paper is again transferred to a mixer equipped with a heating / cooling device, a concentrating device, and each raw material / auxiliary charging device. Ion exchange water having a conductivity of 1 μS / cm was added, and the mixture was stirred and dispersed uniformly at 50 rpm. The dispersion concentration was adjusted to 20% (solid content) to obtain a dispersion of core particles D1.

While stirring, 3 parts (solid content) of the polymer primary particle dispersion C1 was added dropwise to the dispersion of the core particles D1 and kept at room temperature for 60 minutes. Then, it was dripped at the addition amount of 1N NaOH solution 7.5g / 1L dispersion volume, and it hold | maintained at room temperature for further 1 hour. Thereafter, the dispersion was heated to an internal temperature of 55 ° C. over 30 minutes and held for 30 minutes.
Thereafter, the slurry obtained by cooling to 30 ° C. over 10 minutes was extracted, and suction filtered with an aspirator using 5 types C (No. 5C, manufactured by Toyo Roshi Kaisha, Ltd.). The cake remaining on the filter paper is transferred to a stainless steel container equipped with a stirrer (propeller blade), and ion-exchanged water having an electric conductivity of 1 μS / cm is added and dispersed uniformly by stirring at 50 rpm, and then stirred for 30 minutes. It was.

  After that, using 5 C filter paper again, it is suction filtered with an aspirator. The solid matter remaining on the filter paper is equipped with a stirrer (propeller blade) again, and a stainless steel container containing ion-exchanged water with an electric conductivity of 1 μS / cm. The mixture was uniformly dispersed by stirring at 50 rpm, and the mixture was stirred for 30 minutes. When this process was repeated twice, the electrical conductivity of the filtrate was 2 μS / cm.

The cake obtained here was dried for 48 hours in a blower dryer set at 40 ° C. to obtain toner mother particles D1-1.
The volume median particle size (Dv50) of the toner mother particles D1-1 measured using Multisizer III was 8.3 μm, and the average circularity measured by a flow particle analyzer was 0.98.

<Manufacture of developing toner E1>
Into sample mill LSMK manufactured by AS ONE Co., Ltd., 100 parts of toner base particles D1-1 were added, and then 0.5 parts of silica fine particles having a volume average primary particle size of 0.03 μm hydrophobized with aminosilane were added. Stir and mix for 2 minutes. Thereafter, 1.0 part of silica fine particles having a volume average primary particle size of 0.01 μm hydrophobized with aminosilane was added, stirred for 2 minutes in total, mixed and sieved to obtain developing toner E1.

<Manufacture of toner F1 for observing toner surface by ultrasonic peeling of external additive>
40 ml of 1.2% aqueous solution of Triton X-100 (manufactured by Kishida Chemical Co., Ltd.) is added to 2.0 g of the developing toner E1, and stirred for 5 minutes with a stirrer 300 rpm (stirring blade R1311 turbine type stirring blade IKA Japan) in a 100 ml beaker. Disperse the toner. Ultrasonic homogenizer VC
X750 (Ieda Trading Co., Ltd.) (standard probe type 630-0220) is placed in the beaker dispersion so that the probe tip is 2 to 3 mm from the bottom of the beaker, and the Energ is 37% in amplitude.
y12KJ ultrasound was applied.

The toner dispersion was quickly transferred to a 50 ml centrifuge tube with a lid (IWAKI centrifugal sedimentation tube (round bottom, with screw cap) 8422CTF50), and the whole centrifuge tube was quickly cooled with water. Kubota Centrifuge 5
520, and centrifuged at a centrifugal force of 646G for 3 minutes. The centrifuge tube was removed from the centrifuge and the supernatant was discarded.
Further, 40 ml of demineralized water is put into a centrifuge tube, the centrifuge tube is covered, and the toner precipitated by a test tube mixer or hand shake is redispersed in demineralized water. The mixture was centrifuged for 3 minutes under the same conditions, and the supernatant was discarded in the same manner. The same operation was performed twice.

Set a Whatman Grade 5 filter paper on a bifunnel funnel (for 5.5 cm diameter filter paper), drop the desalted water over several milliliters or more in a suction state to make the filter paper adhere to the funnel, and put about 10-20 ml of desalted water into the centrifuge tube. In addition, the precipitated toner was loosened by a test tube mixer or hand shaking, and the toner was taken out on a filter paper. Add about 5-20 ml of demineralized water to the centrifuge tube once more so that the toner does not remain in the centrifuge tube, take out the toner on the filter paper, filter it, and remove the toner when the moisture is removed moderately (several minutes). Together with the filter paper, it was taken out into a 200 ml beaker and naturally dried at room temperature to obtain toner F1 for toner surface observation.

[Example 2]
<Preparation of polymer primary particle dispersion B2>
A reactor equipped with a stirrer (three blades), a heating / cooling device, a concentrating device, and a raw material / auxiliary charging device was charged with 36.0 parts of wax dispersion A1 and 259 parts of demineralized water, and a nitrogen stream while stirring. The temperature was raised to 90 ° C.

Thereafter, the following mixture of monomers and emulsifier solution was added over 300 minutes while stirring was continued. The time when the dropping of the mixture of the monomers and the aqueous emulsifier solution was started as polymerization initiation, the following aqueous initiator solution 1 was added over 270 minutes after the initiation of polymerization, and the aqueous initiator solution 2 was further added over 60 minutes. Thereafter, the inner temperature was maintained at 90 ° C. for 1 hour under stirring.
[Monomers]
Styrene 65.5 parts Butyl acrylate 34.5 parts Acrylic acid 1.0 part Trichlorobromomethane 1.0 part Hexanediol diacrylate 1.2 parts [Emulsifier aqueous solution]
20% DBS aqueous solution 1.0 part demineralized water 67.1 parts [initiator aqueous solution 1]
8% aqueous hydrogen peroxide solution 15.5 parts 8% L-(+) ascorbic acid aqueous solution 15.5 parts [initiator aqueous solution 2]
8% L-(+) Ascorbic acid aqueous solution 14.2 parts After the completion of the polymerization reaction, the mixture was cooled to obtain a milky white primary polymer particle dispersion B2. The median diameter (D50) measured using a nanotrack was 260 nm. The weight average molecular weight (Mw) was 56000. The glass transition temperature (Tg) measured using DSC was 36 ° C.

<Preparation of polymer primary particle dispersion B3>
A reactor equipped with a stirrer (three blades), a heating / cooling device, a concentrating device, and a raw material / auxiliary charging device was charged with 35.9 parts of wax dispersion A1 and 259 parts of demineralized water, and a nitrogen stream while stirring. The temperature was raised to 90 ° C.
Thereafter, the following mixture of monomers and emulsifier solution was added over 300 minutes while stirring was continued. The time when the dropping of the mixture of the monomers and the aqueous emulsifier solution was started as polymerization initiation, the following aqueous initiator solution 1 was added over 270 minutes after the initiation of polymerization, and the aqueous initiator solution 2 was further added over 60 minutes. Thereafter, the inner temperature was maintained at 90 ° C. for 1 hour under stirring.

[Monomers]
Styrene 72.3 parts Butyl acrylate 27.7 parts Acrylic acid 1.5 parts Trichlorobromomethane 1.0 part Hexanediol diacrylate 1.2 parts [Emulsifier aqueous solution]
20% DBS aqueous solution 1.0 part Demineralized water 67.5 parts [Initiator aqueous solution 1]
8% aqueous hydrogen peroxide solution 15.5 parts 8% L-(+) ascorbic acid aqueous solution 15.5 parts [initiator aqueous solution 2]
8% L-(+) ascorbic acid aqueous solution 14.2 parts

After completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer primary particle dispersion B1. The median diameter (D50) measured using a nanotrack was 260 nm. The weight average molecular weight (Mw) was 88000. The glass transition temperature (Tg) measured using DSC was 43 ° C.

<Manufacture of dispersion liquid of core mother particle D2>
At room temperature (about 25 ° C.), 90 parts of polymer primary particle dispersion B2 (solid content) in a mixer equipped with a stirrer (double helical blade), heating / cooling device, concentrating device, and raw material / auxiliary charging device After cooling to 10 ° C. or less, 7.2 parts (solid content) of a colored dispersion was added over 5 minutes and mixed uniformly, and then 0.3 part of 0.5% aluminum sulfate solution ( Solid content) was added dropwise. The temperature was further raised to 35 ° C. over 90 minutes. Here, the volume median particle size (Dv50) was measured using a multisizer, and when the particle size exceeded the target particle size of 6 microns, 10 parts (solid content) of the polymer primary particle dispersion B3 was charged at 35 ° C. Hold for 60 minutes. And after adding 4.0 parts (solid content) of 20% DBS aqueous solution, it heated up to 97 degreeC over 60 minutes, and hold | maintained for 50 minutes.

  Thereafter, the slurry obtained by cooling to 30 ° C. over 20 minutes was extracted, and suction filtered with an aspirator using 5 types C (No. 5C, manufactured by Toyo Roshi Kaisha, Ltd.). The cake remaining on the filter paper is transferred to a stainless steel container equipped with a stirrer (propeller blade), and ion-exchanged water having an electric conductivity of 1 μS / cm is added and dispersed uniformly by stirring at 50 rpm, and then stirred for 30 minutes. It was.

After that, again using 5 kinds C filter paper and suction filtration with an aspirator, the solid matter remaining on the filter paper is again transferred to a mixer equipped with a heating / cooling device, a concentrating device, and each raw material / auxiliary charging device. Ion exchange water having a conductivity of 1 μS / cm was added, and the mixture was stirred and dispersed uniformly at 50 rpm. The dispersion concentration was adjusted to 20% (solid content) to obtain a dispersion of core mother particles D2. Volume median particle size of toner base particle D2 measured using Multisizer III (Dv50
) Was 6.5 μm, and the average circularity measured by a flow particle analyzer was 0.97.

<Production of Toner Base Particle D2-1>
While stirring, 3.0 parts (solid content) of the polymer primary particle dispersion C1 was added dropwise to the dispersion of the core mother particle D2, and the mixture was held at room temperature for 60 minutes. Then, it was dripped at the addition amount of 1N NaOH solution 7.5g / 1L dispersion volume, and it hold | maintained at room temperature for further 1 hour. Thereafter, the dispersion was heated to an internal temperature of 50 ° C. over 30 minutes and held for 30 minutes.

  Thereafter, the slurry obtained by cooling to 30 ° C. over 10 minutes was extracted, and suction filtered with an aspirator using 5 types C (No. 5C, manufactured by Toyo Roshi Kaisha, Ltd.). The cake remaining on the filter paper is transferred to a stainless steel container equipped with a stirrer (propeller blade), and ion-exchanged water having an electric conductivity of 1 μS / cm is added and dispersed uniformly by stirring at 50 rpm, and then stirred for 30 minutes. It was.

After that, using 5 C filter paper again, it is suction filtered with an aspirator. The solid matter remaining on the filter paper is equipped with a stirrer (propeller blade) again, and a stainless steel container containing ion-exchanged water with an electric conductivity of 1 μS / cm. The mixture was uniformly dispersed by stirring at 50 rpm, and the mixture was stirred for 30 minutes. When this process was repeated twice, the electrical conductivity of the filtrate was 2 μS / cm.
The cake obtained here was dried for 48 hours in an air dryer set at 40 ° C. to obtain toner mother particles D2-1.

<Manufacture of development toner E2>
Into sample mill LSMK manufactured by ASONE Co., Ltd., 100 parts of toner base particles D2-1 are added, followed by addition of 0.5 parts of silica fine particles having a volume average primary particle size of 0.03 μm hydrophobized with polydimethylsiloxane. The mixture was stirred and mixed for a total of 3 minutes. Subsequently, 0.6 part of silica fine particles having a volume average primary particle size of 0.02 μm hydrophobized with aminosilane was added and stirred and mixed for a total of 3 minutes. Thereafter, 1.0 part of silica fine particles having a volume average primary particle size of 0.01 μm hydrophobized with aminosilane was added, stirred for 3 minutes in total, mixed and sieved to obtain developer toner E2.

<Manufacture of toner surface observation toner F2 by ultrasonic peeling of external additive>
Developing toner E1 8.0 g is charged with 40 ml of 1.2% aqueous solution of Triton X-100 (manufactured by Kishida Chemical), and stirred for 5 minutes with a stirrer 300 rpm (stirring blade R1311 turbine type stirring blade IKA Japan) in a 100 ml beaker. Disperse the toner. Ultrasonic homogenizer VC
Place X750 (Ieda Trading Co., Ltd.) (standard probe type 630-0220) probe tip into the beaker dispersion so that the tip of the beaker is 2 to 3 mm from the bottom of the beaker. After the liquid was cooled to 30 ° C. or lower, an ultrasonic energy of 12 KJ was further applied, and an ultrasonic dispersion operation of 12 energy energy was performed three times.

The toner dispersion was quickly transferred to four centrifuge tubes with 50 ml lids (IWAKI centrifugal sedimentation tube (round bottom, with screw cap) 8422CTF50), and the whole centrifugation tube was quickly cooled with water. Using a Kubota centrifuge 5520, the mixture was centrifuged for 3 minutes at a centrifugal force of 646G. The centrifuge tube was removed from the centrifuge and the supernatant was discarded.
Further, 40 ml of demineralized water is put in each centrifuge tube, the centrifuge tube is covered, and the toner precipitated by a test tube mixer or hand shaking is redispersed in the demineralized water. The mixture was centrifuged for 3 minutes under the same conditions, and the supernatant was discarded in the same manner. The same operation was performed twice.

Set a Whatman Grade 5 filter paper on a bifunnel funnel (for 5.5 cm diameter filter paper), drop the desalted water over several milliliters or more in a suction state to make the filter paper adhere to the funnel, and put about 10-20 ml of desalted water into the centrifuge tube. In addition, the precipitated toner was loosened by a test tube mixer or hand shaking, and the toner was taken out on a filter paper. Demineralized water 5 once more in the centrifuge tube so that no toner remains in the centrifuge tube
Add ~ 20ml, take out the toner on the filter paper, filter, and when the moisture is removed moderately (several minutes), take the toner into the 200ml beaker together with the filter paper and let it dry naturally at room temperature. F2 was obtained.

[Example 3]
<Manufacture of toner mother particle D2-2>
The amount of polymer primary particle dispersion C1 added is the same as that of D2-1 except that 2.0 parts (solid content) is added instead of 3.0 parts (solid content). 2 was obtained.
<Manufacture of developing toner E3>
A developing toner E3 was obtained in the same manner as the developing toner E2, except that the toner base particles D2-2 were used instead of the toner base particles D2-1.

<Manufacture of toner surface observation toner F2 by ultrasonic peeling of external additive>
A toner surface observation toner F3 was obtained in the same manner as the toner surface observation toner F2, except that the development toner E3 was used instead of the development toner E2.

[Example 4]
<Manufacture of toner mother particles D2-3>
The amount of addition of the polymer primary particle dispersion C1 is the same as that of D2-1 except that 5.0 parts (solid content) is added instead of 3.0 parts (solid content). 3 was obtained.

<Manufacture of developing toner E4>
A developing toner E4 was obtained in the same manner as the developing toner E2, except that the toner base particles D2-3 were used instead of the toner base particles D2-1.
<Manufacture of Toner F4 for Toner Surface Observation by Ultrasonic Peeling of External Additive>
A toner surface observation toner F4 was obtained in the same manner as the toner surface observation toner F2, except that the development toner E4 was used instead of the development toner E2.

[Comparative Example 1]
<Manufacture of toner mother particles D2-4>
The amount of addition of the polymer primary particle dispersion C1 is the same as that of D2-1 except that 1.5 parts (solid content) is added instead of 3.0 parts (solid content). 4 was obtained.
<Manufacture of developing toner E5>
A developing toner E5 was obtained in the same manner as the developing toner E2, except that the toner base particles D2-4 were used instead of the toner base particles D2-1.

<Production of Toner F5 for Toner Surface Observation by Ultrasonic Peeling of External Additive>
A toner surface observation toner F5 was obtained in the same manner as the toner surface observation toner F2, except that the development toner E5 was used instead of the development toner E2.
[Comparative Example 2]
<Production of Toner F6 for Toner Surface Observation by Ultrasonic Peeling of External Additive>
The toner surface observation toner F6 was obtained in the same manner as the toner surface observation toner F5 except that the frequency of ultrasonic dispersion of Energy 12KJ was set to one instead of three.

[Comparative Example 3]
<Manufacture of toner mother particle D2>
The dispersion of the core mother particle D2 is suction filtered using an aspirator using 5 C filter paper, and the solid matter remaining on the filter paper is again equipped with a stirrer (propeller blade) and ion-exchanged water having an electric conductivity of 1 μS / cm. The sample was transferred to a stainless steel container containing, and uniformly dispersed by stirring at 50 rpm, and the mixture was stirred for 30 minutes. When this process was repeated twice, the electrical conductivity of the filtrate was 2 μS / cm.

The cake obtained here was dried for 48 hours in a blower dryer set at 40 ° C. to obtain toner mother particles D2.
<Manufacture of developing toner E6>
Toner for development other than using toner mother particle D2 instead of toner mother particle D2-1 and adding 3.0 parts (solid content) of lyophilized polymer primary particle dispersion C1 at the first stage of external addition A developing toner E6 was obtained in the same manner as in E2.

<Manufacture of toner surface observation toner F7 by ultrasonic peeling of external additive>
A toner surface observation toner F7 was obtained in the same manner as the toner surface observation toner F2, except that the development toner E6 was used instead of the development toner E2.
The toner mother particles or developing toner particles obtained in the examples and comparative examples were used for evaluation by the following methods.

<Charge amount>
Powder Tech Co., Ltd. F-150 is used as a carrier, and 10 g of a toner mother particle or toner particle for development and a carrier having a weight ratio of 1:24 is placed in a glass sample bottle having a capacity of 30 ml, and the temperature is 25 ° C. After storing for 12 hours or more under the condition of 50% humidity and shaking for 1 minute at a frequency of 600 rpm in a mixer mill manufactured by Mitamura Riken Kogyo Co., Ltd., 0.1 g is used for blow-off charge from Toshiba Chemical Corporation. The charge amount was measured by a suction blow-off method using a measuring device.
Blowing conditions: 0.05 kgf x 3 seconds Suction pressure: 350-400 mmH2O
Screen: 400 mesh

<Blocking resistance>
5 g of developing toner is put in a cylindrical container having an inner diameter of 3 cm and a height of 6 cm, and a load of 40 g is put on it and left in an environment having a temperature of 50 ° C. and a humidity of 40% for 24 hours. The degree of aggregation was confirmed by applying a load.
A (good): collapses with a load of less than 200 g.
○ (Practical use possible): It collapses with a load of less than 500 g.
X (Unusable): Aggregates and does not collapse unless a load of 500 g or more is applied.

<Image quality evaluation>
Using the resulting toner, an organic photoreceptor that is charged with a developing rubber roller, a metal blade, and a charging roller (PCR) at a printing speed of 21 ppm, a non-magnetic single component, a guaranteed number of 12,000 sheets (at 5% printing), and a thermal fixing system. Continuous printing was performed at a printing rate of 5% using a commercially available printer (Brother's HL2140) equipped with a roller fixing machine.

<Measurement method of fog>
Using an image forming apparatus, the color difference of the white background of each standard paper (OKI Excellent White) before and after printing was measured with X-Rite 938 (manufactured by X-Rite), and the magnitude of ΔE Based on the following criteria.
◎ (good): △ E <1.0
○ (slightly generated): 1.0 ≦ ΔE <1.5
X (Generation): 1.5 ≦ ΔE

<Fixing test>
The fixing machine is a heat roll fixing system, and the heating roller of the fixing machine has a release layer made of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) and was evaluated without application of silicone oil. Evaluation was performed without application of silicone oil. A recording paper (FC Dream made by Kishu Paper) carrying an unfixed toner image with an adhesion amount of 300% (attachment amount of about 1.0 mg / cm 2) is prepared, and the surface temperature of the heating roller is 5 ° C. from 100 ° C. to 210 ° C. It was changed in increments, conveyed to the fixing nip portion, and the fixing state was observed when discharged at a speed of 198 mm / sec. The temperature range where the toner on the recording paper after fixing does not cause toner offset or paper wrapping at the time of fixing and the toner on the recording paper after fixing is sufficiently adhered to the recording paper is defined as the fixing temperature range. The minimum fixing temperature at which the toner on the recording paper after fixing can sufficiently adhere to the recording paper represents the low temperature fixing property of the toner, and the lower the temperature, the better the low temperature fixing property.

As the fixing temperature range ΔT in the fixing temperature region, the fixing temperature range was determined according to the following criteria.
ΔT = Tmax (maximum fixing temperature)-Tmin (minimum fixing temperature)
◎ ΔT ≧ 50 ℃
○ 50 ℃> ΔT ≧ 30 ℃
× ΔT <30 ° C
As the minimum fixing temperature Tmin, the low-temperature fixability of the toner was determined according to the following criteria.
◎ Tmin ≦ 125 ℃
○ 125 ℃ <Tmin ≦ 140 ℃
× Tmin> 140 ° C

<SEM observation and image analysis of toner>
<SEM observation and image analysis of toner>
The surface of the toner mother particles was observed using a SEM apparatus. The SEM equipment used was a Zeiss ULTRA55 and a Hitachi S4500. At an acceleration voltage of 1.5 to 5 k∨, 10,000 and 50,000 times observed images of the toner surface were obtained.

Using an image processing program (WinROOF manufactured by MITANI), the toner center (2.2 μm x
Apply a median filter to the 50,000 times SEM observation image in the 1.6μm range to remove noise, perform flattening processing, and change the density using a lookup table to make it easier to extract particles adhering to the core particle surface. It was. The density of the mode value of the histogram was changed to the minimum and the maximum was changed with the curve of gamma 2.7. Finally, the ratio of the projected area of the adhered particles to the projected area of the core particles was measured by an automatic threshold method. In the analysis, six SEM photographs were used, and the average value of the results of the six analysis was defined as the occupancy ratio of the projected area of all attached particles including shell particles and external additive particles to the projected area of the core particles.

  Furthermore, in order to calculate the area occupancy of only the adhered shell particles by utilizing the fact that the external additive particles are smaller in diameter than the shell particles, the measured values are obtained by calibration based on the scale displayed in the SEM observation photograph. In terms of the actual length, particles smaller than a circle area corresponding to a diameter of 50 nm with respect to the projected area of each adhered particle were automatically removed from the analysis software, and the area occupation ratio of particles having a diameter corresponding to a remaining circle of 50 nm or more was measured.

The evaluation results are summarized in Table 1 below.
With respect to the area occupancy ratio of the toner surface adhering particles in Table 1, “toner base particles” means toner base particles that have not been dry-added externally, and “sonication toner particles” refers to the toner base particles described above. The toner base particles are in a state after being dry-added and after being dispersed in an aqueous system and after the external additive has been peeled off by ultrasonic waves.

“Sonicated Toner Particles All” is the projected area of all the fine particles including the external additive remaining without being separated from the shell particles with respect to the projected area of the core particles in the toner base particles after the external additives are removed by ultrasonic waves. Means occupancy.
“Diameter 50 nm or more” means that the “ultrasonic treatment toner particles All” excludes external additive particles smaller than the equivalent circle diameter of 50 nm, and occupies the projected area of fine particles mainly composed of shell particles with respect to the projected area of core particles Means.

  “Diameter 50 nm or less” means the occupancy ratio of the projected area of the external additive smaller than the equivalent circle diameter of 50 nm with respect to the projected area of the core particles, ) And the occupancy ratio of the projected area of particles with a circle-equivalent diameter of 50 nm or more ("Diameter 50 nm or more" column).

As shown in the evaluation results of Table 1 above, the coverage of the shell particles to the core particles on the outermost surface of the toner is measured by SEM observation of the surface of the toner base particles from which the externally added particles are sufficiently peeled off by ultrasonic waves. I was able to. When the external additive particles cannot be sufficiently peeled as in Comparative Example 2, it is difficult to accurately measure the coverage of the shell particles.
Even if the toner coated on the outermost surface of the toner base particles of the resinous shell particles is subjected to ultrasonic treatment, a high coverage can be maintained on the outermost surface of the toner, and the performance of these toners was confirmed. It was confirmed that when the covering ratio of the shell particles was 25% or more, it had excellent blocking resistance and low-temperature fixing performance.

In the present invention, the shell particles are coated on the surface of the core particles with high efficiency, and at the same time, by adding a charge control agent to the shell particles, high blocking resistance and good low-temperature fixability are realized. As a result, toner charge control could be realized.
As in Comparative Example 3, in the method of adding particles containing a charge control agent during external addition, the adhesion strength to the toner base particles is low, the core-shell structure in which the shell particles are uniformly coated cannot be formed, and blocking resistance is prevented. The toner performance including the chargeability and chargeability was not improved.

Claims (10)

  A toner having toner base particles containing at least a binder resin and a colorant and an external additive, wherein the toner base particles have a core-shell structure having core particles and shell particles, and the toner is subjected to ultrasonic treatment A toner for developing an electrostatic charge image, wherein the ratio of the projected area of the shell particles to the projected area of the core particles is from 25% to 60%.   The electrostatic charge image developing toner according to claim 1, wherein the shell particles have charge control performance.   The electrostatic charge image developing toner according to claim 1, wherein the shell particles are resin fine particles.   4. The electrostatic charge image developing toner according to claim 1, wherein a volume average particle diameter of the shell particles is 50 nm or more and 150 nm or less. 5.   5. The electrostatic image developing toner according to claim 1, wherein the content of the shell particles in the toner is 10 wt% or less with respect to the toner base particles. 6.   4. The electrostatic charge image developing toner according to claim 3, wherein the resin glass transition temperature (Tg) of the shell particles is equal to or higher than the glass transition temperature (Tg) of the binder resin of the toner base particles.   7. The electrostatic charge image developing toner according to claim 3, wherein the shell particles have a quaternary ammonium salt and a tertiary amine functional group, and have a positive chargeability.   8. The electrostatic image developing toner according to claim 3, wherein the shell particles are obtained by an emulsion polymerization method.   The electrostatic image developing toner according to claim 1, wherein the core particles are obtained by a polymerization method.   10. The toner base particles according to claim 1, wherein the toner base particles are obtained through a wet capsule process in which the dispersion of shell particles is mixed with the dispersion of core particles and attached to the surface of the core particles. The toner for developing an electrostatic charge image according to any one of the above.