JP2017156541A - Method for manufacturing toner for electrostatic charge image development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a toner for electrostatic charge image development that has improved heat-resistant storage property, fluidity, low-temperature fixability, document offset resistance, and image quality.SOLUTION: The present method for manufacturing a toner for electrostatic charge image development is a method for manufacturing a toner for electrostatic charge image development containing core-shell type toner base particles containing a binder resin and a mold release agent, where the binder resin contains a styrene-acrylic resin, a crystalline polyester resin, and an amorphous polyester resin; the method includes specific steps I to VI.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing an electrostatic charge image developing toner. More specifically, the present invention relates to a method for producing a toner for developing an electrostatic image having improved heat storage stability, fluidity, low-temperature fixability, document offset resistance and image quality.

  In recent years, in electrophotographic process machines that employ dry toner developers, there is a need to expand media compatible with dry toner developers, reduce environmental impact, improve image quality such as image quality and document offset, and improve the stability of these characteristics. ing.

  As a means to achieve media compatibility, environmental impact reduction, and document offset of dry toner developers, crystalline resins (such as crystalline polyester) that melt with low thermal energy during fixing and quickly solidify after printing, There is a method of using the binder resin contained in the toner for developing an electrostatic image.

In addition, there is a method in which an amorphous polyester resin, a styrene-acrylic resin, or the like is used as a binder resin contained in an electrostatic charge image developing toner.
Among them, the amorphous polyester resin can be designed at a low softening point (T _sp ) while having a high glass transition temperature (T _g ). For this reason, the amorphous polyester resin can be used for the binder resin as a material superior in achieving both heat-resistant storage stability and low-temperature fixability of the toner.
On the other hand, by using styrene-acrylic resin as the binder resin, it is possible to synthesize toner with low raw material costs.

Examples of the method for producing toner base particles containing these binder resins include a melt-kneading pulverization method, a suspension polymerization method, and an emulsion aggregation method. Among these, the emulsion polymerization aggregation method is particularly preferable because each particle can be precisely aggregated and arranged in an aqueous medium, and the particle shape controllability is superior.
On the other hand, a polyester resin and a styrene-acrylic resin are generally incompatible with each other. Therefore, in any production method, when a polyester resin and a styrene-acrylic resin are used in combination, the resin is likely to be localized in the toner and on the surface layer, and it is difficult to control the toner structure and the internal arrangement of each additive. For this reason, for example, when trying to apply a polyester resin and a styrene-acrylic resin to toner particles having a core-shell type structure, a problem due to difficulty in the above control tends to occur.

For example, Patent Document 1 uses an amorphous polyester resin in which a core particle contains a styrene-acrylic resin containing methyl methacrylate and a crystalline polyester resin, and a shell is modified with a styrene-acrylic resin. As a result, the polarity of the styrene-acrylic resin is close to that of the amorphous polyester resin, so that the compatibility is improved and a thin layer shell can be formed. As a result, the fixability (low temperature fixing, separability at fixing) and heat resistance are achieved. A method has been proposed that can improve compatibility and improve document offset resistance.
However, in the technique disclosed in Patent Document 1, the crystalline polyester resin is compatible with the amorphous polyester shell resin during production, and in some cases, surface bleed occurs, resulting in insufficient heat-resistant storage stability. Or when the toner is softly agglomerated due to physical stress during the durability of the developer and causes image defects, or the dispersion of the colorant and the like inside the core resin is non-uniform, resulting in reduced chargeability and transferability. There has been room for improvement with respect to the problem that the image quality is lowered due to the deterioration.

In Patent Document 2, an intermediate layer made of vinyl resin is introduced between the core particles and the shell,
A method has also been proposed in which crystalline polyester is dispersedly arranged inside. However, in addition to the crystalline polyester resin, a low-polarity substance such as a release agent can be easily retained inside, so there is room for improvement in fixing separation property and document offset resistance.

JP 2012-255957 A JP 2014-206610 A

  The present invention has been made in view of the above-mentioned problems and situations, and the problem to be solved is a toner for developing an electrostatic image having improved heat storage stability, fluidity, low-temperature fixability, document offset resistance and image quality. It is to provide a manufacturing method.

In order to solve the above problems, the present inventor, in the process of examining the cause of the above problems, etc., if the shell is formed while adjusting the temperature as described in the following Steps III to V, the amorphous polyester resin In the process of forming a shell using, the domain of the amorphous polyester resin in the surface layer and the surface orientation of the crystalline polyester resin produced by the simultaneous agglomeration / fusion of the amorphous polyester resin (with the amorphous polyester resin and As a result, it has been found that a method for producing a toner for developing an electrostatic image with improved heat storage stability, fluidity, low-temperature fixability, document offset resistance and image quality can be provided. It was.
That is, the said subject which concerns on this invention is solved by the following means.

1. A method for producing a toner for developing an electrostatic image containing core / shell toner base particles containing at least a binder resin and a release agent,
The binder resin includes at least a styrene-acrylic resin, a crystalline polyester resin, and an amorphous polyester resin, and
A method for producing a toner for developing an electrostatic charge image, comprising at least the following steps I to V.
(Step I): Step of adding a flocculant under stirring to a dispersion liquid mixture containing at least the styrene-acrylic resin and the mold release agent (Step II): the flocculant added in Step I The dispersion of the crystalline polyester resin is added to the dispersion mixture, and at least the styrene-acrylic resin, the release agent, and the crystalline polyester resin are aggregated and united under heating and stirring to disperse the core particles. Step of obtaining a liquid (Step III): Step of cooling the core particle dispersion obtained in Step II to a temperature of at least the crystallization peak temperature (T _qc ) of the crystalline polyester resin of −15 ° C. (Step IV): the temperature of the dispersion of the core particles cooled in the step III,
(1) At least the temperature below the melting point (T _mc ) of the crystalline polyester resin,
(2) The glass transition temperature (T _gs ) of the styrene-acrylic resin + 5 ° C. or higher.
(3) the amorphous polyester glass transition temperature of the resin _(T ga) + 3 ° C. and below temperatures and ₍₄₎ the _{T gs} <temperature satisfies the relationship T ga _{<T qc,}
The amorphous polyester resin particle dispersion is added to the core particle dispersion, and the amorphous polyester resin particles are adhered to the surface of the core particles as shell particles. Step of obtaining (Step V): The core-shell particle dispersion is brought to a temperature not lower than the glass transition temperature (T _ga ) of the amorphous polyester resin + 3 ° C. and not higher than the melting point (T _mc ) of the crystalline polyester resin. Adjusting, fusing the core particles, the shell particles, and the shell particles together to obtain a core-shell type toner base particle dispersion liquid

2. In the step IV, the pH of the core particle dispersion at 25 ° C. (pH _A ) and the pH of the amorphous polyester resin particle dispersion at 25 ° C. before addition to the core particle dispersion (pH _B) 2) satisfy the relationship of the following formulas (a) to (c): The method for producing a toner for developing an electrostatic charge image according to item 1.
Formula (a) 3 ≦ pH _A −pH _B
Formula (b) 7 ≦ pH _A ≦ 10
Formula (c) 2 ≦ pH _B ≦ 5

  3. The volume average particle diameter of the amorphous polyester resin particles in the dispersion of the amorphous polyester resin particles added in the step IV is in the range of 50 to 300 nm. Item 3. A method for producing a toner for developing an electrostatic image according to Item 2.

4). The glass transition temperature (T _gs ) of the styrene-acrylic resin is in the range of 35-50 ° C.,
The amorphous polyester resin has a glass transition temperature (T _ga ) in the range of 53 to 63 ° C .;
The toner for developing an electrostatic charge image according to any one of Items 1 to 3, wherein the crystalline polyester resin has a melting point (T _mc ) in a range of 65 to 80 ° C. Production method.

  5. The electrostatic image development according to any one of Items 1 to 4, wherein the amorphous polyester resin is an amorphous polyester resin chemically bonded to a styrene-acrylic resin. Of manufacturing toner.

  By the above means of the present invention, it is possible to provide a method for producing a toner for developing an electrostatic image having improved heat storage stability, fluidity, low-temperature fixability, document offset resistance and image quality.

  The expression mechanism or action mechanism of the above effect of the present invention is not clear, but is presumed as follows.

  In the process of producing the core particles, the crystalline polyester is formed in the state where the dispersion state of the release agent is maintained with respect to the main resin (styrene-acrylic resin) constituting the core particles by setting the process I and the process II. It is considered that core particles that exist in the core particles with good dispersibility can be obtained.

In addition, in the step of attaching the shell particles, as described in Step III and Step IV, after cooling to a temperature of crystallization peak temperature (T _qc ) of −15 ° C. or lower of the crystalline polyester resin, at least the crystalline polyester resin and the melting point (T _mc) below, by the specific temperature range as described in step IV (1) ~ (4) , the release agent in the core particles, was held the dispersion state of the crystalline polyester The shell particles (amorphous polyester resin particles) can be adhered / coated on the surface of the core particles as it is (that is, while suppressing the surface layer orientation of the crystalline polyester resin) and the crystalline polyester is in a crystalline state. I think.

As described in Step V, the glass transition temperature (T _ga ) of the amorphous polyester resin + 3 ° C. or higher and the melting point (T _mc ) of the crystalline polyester resin or lower, the styrene-acrylic resin and the amorphous polyester resin Can be fused between the styrene-acrylic resin, the amorphous polyester resin, and the amorphous polyester resin while maintaining the dispersion / crystalline state of the release agent and the crystalline polyester. It is considered that toner base particles having a uniform composition and shape can be obtained.

  As described above, according to the method for producing a toner of the present invention, toner base particles having a crystalline polyester in a crystalline state and a uniform surface composition and shape can be produced. It is presumed that a toner having excellent properties can be produced. Also, since the release agent can be retained with good dispersibility, it is excellent in fluidity. As a result, it is resistant to stress (developer durability) due to mixing in the developing device etc., and has excellent developability / transferability, image I think that it is possible to produce toner with excellent quality.

  The method for producing a toner for developing an electrostatic charge image according to the present invention is a method for producing a toner for developing an electrostatic charge image containing core-shell type toner base particles containing at least a binder resin and a release agent. The adhesion resin contains at least a styrene-acrylic resin, a crystalline polyester resin, and an amorphous polyester resin, and has at least the steps I to V described above. This feature is a technical feature common to or corresponding to the inventions according to claims 1 to 5.

As an embodiment of the present invention, in Step IV, the dispersion of the amorphous polyester resin particles before adding to the core particle dispersion (pH _A ) at 25 ° C. and the core particle dispersion in Step IV. That the pH at 25 ° C. (pH _B ) satisfies the relationship of the above formulas (a) to (c) can cause aggregation to the core particles while suppressing aggregation (homo aggregation) between the shell particles. To preferred.

  In the present invention, the volume average particle diameter of the amorphous polyester resin particles in the dispersion of the amorphous polyester resin particles added in Step IV is in the range of 50 to 300 nm. It is preferable because a desired coverage can be secured with a smaller amount of shell.

In the present invention, the glass transition temperature (T _gs ) of the styrene-acrylic resin is in the range of 35 to 50 ° C., and the glass transition temperature (T _ga ) of the amorphous polyester resin is 53 to 63 ° C. It is within the range, and the melting point (T _mc ) of the crystalline polyester resin is within the range of 65 to 80 ° C., the heat resistance and the plasticizing effect at the time of fixing, the heat resistant storage property and the low temperature fixability are improved. This is preferable because it is possible.

  In the present invention, since the amorphous polyester resin is an amorphous polyester resin chemically bonded to a styrene-acrylic resin, the releasing effect during fixing and the strength of the image after fixing can be improved. preferable.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

≪Outline of manufacturing method of toner for developing electrostatic image≫
The method for producing a toner for developing an electrostatic charge image according to the present invention is a method for producing a toner for developing an electrostatic charge image containing core-shell type toner base particles containing at least a binder resin and a release agent. The adhesive resin includes at least a styrene-acrylic resin, a crystalline polyester resin, and an amorphous polyester resin, and has at least the following steps I to V.

(Step I): Step of adding a flocculant under stirring to a dispersion liquid mixture containing at least the styrene-acrylic resin and the mold release agent (Step II): the flocculant added in Step I The dispersion of the crystalline polyester resin is added to the dispersion mixture, and at least the styrene-acrylic resin, the release agent, and the crystalline polyester resin are aggregated and united under heating and stirring to disperse the core particles. Step of obtaining a liquid (Step III): Step of cooling the core particle dispersion obtained in Step II to a temperature of at least the crystallization peak temperature (T _qc ) of the crystalline polyester resin of −15 ° C. (Step IV): the temperature of the dispersion of the core particles cooled in the step III,
(1) At least the temperature below the melting point (T _mc ) of the crystalline polyester resin,
(2) The glass transition temperature (T _gs ) of the styrene-acrylic resin + 5 ° C. or higher.
(3) the amorphous polyester glass transition temperature of the resin _(T ga) + 3 ° C. and below temperatures and ₍₄₎ the _{T gs} <temperature satisfies the relationship T ga _{<T qc,}
The amorphous polyester resin particle dispersion is added to the core particle dispersion, and the amorphous polyester resin particles are adhered to the surface of the core particles as shell particles. Step of obtaining (Step V): The core-shell particle dispersion is brought to a temperature not lower than the glass transition temperature (T _ga ) of the amorphous polyester resin + 3 ° C. and not higher than the melting point (T _mc ) of the crystalline polyester resin. Adjusting, fusing the core particles, the shell particles, and the shell particles together to obtain a core-shell type toner base particle dispersion liquid

In addition, the manufacturing method of the electrostatic image developing toner of the present invention may further include the following step VI in addition to the above steps I to V.
(Step VI): After cooling the core / shell type toner base particle dispersion obtained in Step V, the core / shell type toner base particle is separated from the core / shell type toner base particle dispersion and dried. Process

Crystallization peak temperature of the crystalline polyester resin according to the production method of the present invention (T _qc), melting point (T _mc) of the crystalline polyester _resin, a styrene - glass transition temperature of the acrylic resin (T _gs), amorphous polyester resin The glass transition temperature (T _ga ) is measured as follows. Incidentally, the crystallization peak temperature of the crystalline polyester resin _{(T qc),} the melting point of the crystalline polyester resin _{(T mc),} styrene - glass transition temperature _{(T gs)} acrylic resin, the glass transition temperature of the amorphous polyester resin ( _Tga ) can be adjusted by adjusting the composition (blending amount) of monomers for polymerizing each resin and the molecular weight of each resin.

(Measurement of melting point (T _mc ) and crystallization peak temperature (T _qc ) of crystalline polyester resin)
The melting point (T _mc ) of the crystalline polyester resin can be determined by performing differential scanning calorimetry of the toner. A differential scanning calorimeter “Diamond DSC” (manufactured by Perkin Elmer) is used for differential scanning calorimetry. Specifically, the measurement is performed at a temperature rising rate of 10 ° C./min from room temperature (25 ° C.) to 150 ° C., and the temperature is raised at 150 ° C. for 5 minutes. Measurement conditions for cooling from 150 ° C. to 0 ° C., maintaining the temperature isothermally at 0 ° C. for 5 minutes, and the second temperature raising process for raising the temperature from 0 ° C. to 150 ° C. at a rate of 10 ° C./min What is necessary is just to carry out according to (temperature rising / cooling conditions). The above measurement can be performed by enclosing 3.0 mg of toner in an aluminum pan and setting it in a sample holder of a differential scanning calorimeter “Diamond DSC”. An empty aluminum pan may be used as a reference.
In the above measurement, analysis is performed from the endothermic curve obtained by the first temperature raising process, and the top temperature of the endothermic peak derived from the crystalline polyester resin is defined as the melting point (T _mc ) (° C.) of the crystalline polyester resin. Moreover, it analyzes from the exothermic curve obtained by a cooling process, and makes the temperature of the exothermic peak top derived from crystalline polyester resin into the crystallization peak temperature ( _Tqc ) ( _degreeC ) of crystalline polyester resin.

(Measurement of glass transition temperature ( _Tgs , _Tga ) of styrene-acrylic resin and amorphous polyester resin)
In the DSC same apparatus, the glass transition temperature is measured under the following conditions: a measurement temperature of 0 to 150 ° C., a temperature increase rate of 10 ° C./min, a temperature decrease rate of 10 ° C./min, and heat-cool-heat temperature control. 2nd. Perform analysis based on the data in Heat, draw an extension of the baseline before the rise of the first endothermic peak, and a tangent line indicating the maximum slope between the rise of the first peak and the peak apex, and its intersection Glass transition temperature.

  In the following, with respect to the core-shell type toner base particles contained in the electrostatic image developing toner produced by the method for producing an electrostatic image developing toner of the present invention, the components and the like are described, and then the process I to Step VI will be described in detail.

[Core-shell type toner base particles]
The toner base particles according to the present invention are core-shell type toner base particles having a core-shell structure. The core / shell structure refers to a structure having a core particle and a shell covering the core particle. The shell may be formed of a large film (hereinafter also referred to as “shell film”) or may be composed of several film-like domains (hereinafter also referred to as “film-like domains”). It may be. Further, when it is not necessary to distinguish between the shell film and the membranous domain, these are collectively referred to as a shell.
Further, an external additive is added to the toner base particles as necessary. The toner base particles to which the external additive is added may be used as toner particles. When no external additive is added, the toner base particles may be used as toner particles as they are. A collection of toner particles is referred to as toner.

<Binder resin>
The binder resin includes at least a styrene-acrylic resin, a crystalline polyester resin, and an amorphous polyester resin.
The binder resin contains other materials such as resins and organic compounds other than styrene-acrylic resin, crystalline polyester resin, and amorphous polyester resin, as long as the effects of the present invention are not impaired. May be.

<Styrene-acrylic resin>
A styrene-acrylic resin is a resin in which a styrene monomer and an acrylic monomer are polymerized.
It is ensured that the weight average molecular weight (Mw) of the styrene-acrylic resin is in the range of 25000 to 60000 and the number average molecular weight (Mn) is in the range of 8000 to 20000, and low temperature properties and gloss stability are ensured. From the viewpoint of
The glass transition temperature (T _gs ) of the styrene-acrylic resin is preferably in the range of 35 to 50 ° C., more preferably in the range of 38 to 48 ° C. from the viewpoint of obtaining low-temperature fixability.

The polymerizable monomer used in the styrene-acrylic resin is preferably an aromatic vinyl monomer or a (meth) acrylic acid ester monomer and having an ethylenically unsaturated bond capable of radical polymerization.
For example, aromatic vinyl monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-
Chlorostyrene, p-ethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, Examples thereof include pn-dodecylstyrene, 2,4-dimethylstyrene, 3,4-dichlorostyrene, and derivatives thereof. These aromatic vinyl monomers can be used alone or in combination of two or more.

  (Meth) acrylic acid ester monomers include n-butyl acrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate Butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate. These (meth) acrylic acid ester monomers can be used alone or in combination of two or more. Among the above, it is preferable to use a combination of a styrene monomer and an acrylate monomer or a methacrylate ester monomer.

A third vinyl monomer can also be used as the polymerizable monomer. Examples of the third vinyl monomer include acid monomers such as acrylic acid, methacrylic acid, maleic anhydride and vinyl acetic acid, and acrylamide, methacrylamide, acrylonitrile, ethylene, propylene, butylene vinyl chloride, N-vinylpyrrolidone and butadiene. It is done.
As the polymerizable monomer, a polyfunctional vinyl monomer may be further used. Examples of the polyfunctional vinyl monomer include diacrylates such as ethylene glycol, propylene glycol, butylene glycol and hexylene glycol, dimethacrylates and trimethacrylates of tertiary alcohols such as divinylbenzene, pentaerythritol, and trimethylolpropane. Can be mentioned.

  The styrene-acrylic resin according to the present invention is preferably prepared by an emulsion polymerization method. Emulsion polymerization can be obtained by dispersing and polymerizing a polymerizable monomer such as styrene or acrylate in an aqueous medium described later. In order to disperse the polymerizable monomer in the aqueous medium, a surfactant is preferably used, and a polymerization initiator and a chain transfer agent can be used for the polymerization.

<Crystalline polyester resin>
The crystalline polyester resin according to the present invention is a portion derived from a known polyester resin obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyvalent carboxylic acid) and a divalent or higher alcohol (polyhydric alcohol). In the differential scanning calorimetry (DSC) of the toner, it means a resin having a clear endothermic peak, not a stepwise endothermic change. The clear endothermic peak specifically means a peak in which the half-value width of the endothermic peak is within 15 ° C. when measured at a rate of temperature increase of 10 ° C./min in differential scanning calorimetry (DSC). To do.

The melting point (T _mc ) of the crystalline polyester resin is preferably in the range of 65 to 80 ° C., and more preferably in the range of 67 to 78 ° C. By being in this range, both heat resistance and a plasticizing effect during fixing can be achieved.

The crystallization temperature ( _Tqc ) of the crystalline polyester resin is preferably in the range of 50 to 70 ° C, more preferably 55 to 65 ° C. By being in this range, heat resistance and low-temperature fixability can be improved.

The crystalline polyester resin has a structure in which the number of carbons of the main chain of the structural unit derived from the polyhydric alcohol for forming the crystalline polyester resin is _Calcohol and derived from the polyvalent carboxylic acid for forming the crystalline polyester resin. When the number of carbons in the main chain of the unit is C _acid , it is preferable that the following relational expression (A) is satisfied.
Relational expression (A): 5 ≦ | C _acid −C _alcohol ≦≦ 12

  By containing a crystalline polyester resin in which the length of the alkyl chain repeated through an ester bond that satisfies the relational expression (A) is contained in the toner base particles, the crystalline polyester resin is difficult to aggregate. Even in a high temperature environment, the crystalline domain of the crystalline polyester resin is difficult to increase. Therefore, it is possible to obtain an effect that the toner fixing property is hardly lowered even after storage in a high temperature state.

Further, from the viewpoint of more effectively expressing the same effect, it is preferable that the crystalline polyester resin satisfies the following relational expression (B).
Relational expression (B): 6 ≦ | C _acid −C _alcohol ≦≦ 10

Further, from the viewpoint of improving fixability, it is preferable that the crystalline polyester resin satisfies the following relational expression (C).
Relational expression (C): _Calcohol <C _acid

Further, from the viewpoint of improving fixability, the crystalline polyester resin preferably has a carbon number C _alcohol of the main chain of the structural unit derived from the polyhydric alcohol within the range of 2 to 12, It is preferable that the carbon number C _acid of the main chain of the structural unit derived from is in the range of 6-16.

  As the dicarboxylic acid component used as the polyvalent carboxylic acid component, an aliphatic dicarboxylic acid is preferably used, and an aromatic dicarboxylic acid may be used in combination. As the aliphatic dicarboxylic acid, it is preferable to use a linear one. By using a linear type, there is an advantage that crystallinity is improved. The dicarboxylic acid component is not limited to one type, and two or more types may be mixed and used.

  Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid. Acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (dodecanedioic acid), 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1, Examples thereof include 18-octadecanedicarboxylic acid, and these lower alkyl esters and acid anhydrides can also be used.

  Among the above aliphatic dicarboxylic acids, aliphatic dicarboxylic acids having 6 to 14 carbon atoms are preferable because the effects of the present invention are easily obtained.

  Examples of the aromatic dicarboxylic acid that can be used together with the aliphatic dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4′-biphenyldicarboxylic acid. Is mentioned. Among these, terephthalic acid, isophthalic acid, and t-butylisophthalic acid are preferably used from the viewpoints of availability and emulsification ease.

As the dicarboxylic acid component for forming the crystalline polyester resin, the content of the aliphatic dicarboxylic acid is preferably 50 constituent mol% or more, more preferably 70 constituent mol% or more, and still more preferably 80 It is at least 100% by mole, particularly preferably 100% by mole. When the content of the aliphatic dicarboxylic acid in the dicarboxylic acid component is 50 constituent mol% or more, the crystallinity of the crystalline polyester resin can be sufficiently ensured.

  Moreover, it is preferable to use aliphatic diol for the diol component used as a polyhydric alcohol component, and you may contain diols other than aliphatic diol as needed. As the aliphatic diol, a linear diol is preferably used. By using a linear type, there is an advantage that crystallinity is improved. A diol component may be used individually by 1 type and may be used 2 or more types.

  Examples of the aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8- Octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18- Examples include octadecanediol and 1,20-eicosanediol.

  Among the aliphatic diols, the diol component is preferably an aliphatic diol having 2 to 12 carbon atoms, more preferably an aliphatic diol having 4 to 12 carbon atoms, because the effects of the present invention are easily obtained.

  Examples of the diol other than the aliphatic diol used as necessary include a diol having a double bond, a diol having a sulfonic acid group, a diol having a bisphenol skeleton, and more specifically, a diol having a double bond. Examples thereof include 2-butene-1,4-diol, 3-butene-1,6-diol, 4-butene-1,8-diol, and the like.

  As the diol component for forming the crystalline polyester resin, the content of the aliphatic diol is preferably 50 component mol% or more, more preferably 70 component mol% or more, and still more preferably 80 component mol%. % Or more, and particularly preferably 100 constituent mol%. When the content of the aliphatic diol in the diol component is 50 constituent mol% or more, the crystallinity of the crystalline polyester resin can be ensured, and excellent low-temperature fixability can be obtained in the manufactured toner. Glossiness can be obtained in an image formed automatically.

  The use ratio of the diol component to the dicarboxylic acid component is such that the equivalent ratio [OH] / [COOH] of the hydroxy group [OH] of the diol component to the carboxy group [COOH] of the dicarboxylic acid component is 2.0 / 1. 0.0 to 1.0 / 2.0, preferably 1.5 / 1.0 to 1.0 / 1.5, and 1.3 / 1.0 to 1.0 / 1. 3 is particularly preferred.

  The method for forming the crystalline polyester resin is not particularly limited, and a crystalline polyester resin is formed by polycondensation (esterification) of a polyvalent carboxylic acid and a polyhydric alcohol using a known esterification catalyst. be able to.

Known esterification catalysts that can be used in the production of the crystalline polyester resin include alkali metal compounds such as sodium and lithium; compounds containing Group 2 elements such as magnesium and calcium; aluminum, zinc, manganese, antimony, Examples thereof include metal compounds such as titanium, tin, zirconium and germanium; phosphorous acid compounds; phosphoric acid compounds; and amine compounds. Specifically, examples of the tin compound include dibutyltin oxide, tin octylate, tin dioctylate and salts thereof. Titanium compounds include tetranormal butyl titanate, tetraisopropyl titanate, tetramethyl titanate,
Examples include titanium alkoxides such as tetrastearyl titanate; titanium acylates such as polyhydroxytitanium stearate; titanium chelates such as titanium tetraacetylacetonate, titanium lactate, and titanium triethanolamate. Examples of germanium compounds include germanium dioxide. Furthermore, as an aluminum compound, oxides, such as poly aluminum hydroxide, aluminum alkoxide, etc. are mentioned, A tributyl aluminate etc. can be mentioned. You may use these individually by 1 type or in combination of 2 or more types.

  The polymerization temperature is not particularly limited, but is preferably 150 to 250 ° C. The polymerization time is not particularly limited, but is preferably 0.5 to 10 hours. During the polymerization, the pressure in the reaction system may be reduced as necessary.

  The crystalline polyester resin is not particularly limited as long as it is defined above. For example, the crystalline polyester resin itself may be contained, or a hybrid crystalline polyester resin described later may be contained. Hereinafter, the hybrid crystalline polyester resin will be briefly described.

<Hybrid crystalline polyester resin>
The hybrid crystalline polyester resin is a resin in which a crystalline polyester resin segment and an amorphous resin segment other than the polyester resin are chemically bonded.

  A crystalline polyester resin segment refers to a portion derived from a crystalline polyester resin. That is, it refers to a molecular chain having the same chemical structure as that constituting the crystalline polyester resin. Moreover, the amorphous resin segment other than the polyester resin refers to a portion derived from an amorphous resin other than the polyester resin. That is, it refers to a molecular chain having the same chemical structure as that constituting an amorphous resin other than a polyester resin.

(Crystalline polyester resin segment)
The crystalline polyester resin segment is a portion derived from the crystalline polyester resin, and refers to a resin segment having a clear endothermic peak instead of a stepwise endothermic change in the differential scanning calorimetry (DSC) of the toner.

  The crystalline polyester resin segment is not particularly limited as long as it is defined above. For example, this resin is used for a resin having a structure in which other components are copolymerized with the main chain of the crystalline polyester resin segment and a resin having a structure in which the crystalline polyester resin segment is copolymerized with the main chain composed of other components. If the toner to be contained exhibits a clear endothermic peak as described above, the resin corresponds to the hybrid crystalline polyester resin in the present invention.

  The method for forming the crystalline polyester resin segment is not particularly limited, and the polyvalent carboxylic acid and the polyhydric alcohol are polycondensed using a known esterification catalyst in the same manner as the above-described method for forming the crystalline polyester resin ( The segment can be formed by esterification.

  Furthermore, the crystalline polyester resin segment is preferably polycondensed with a compound for chemically bonding to the amorphous resin segment in addition to the polyvalent carboxylic acid and the polyhydric alcohol.

  Here, the hybrid crystalline polyester resin includes an amorphous resin segment other than the polyester resin described later, in addition to the crystalline polyester resin segment.

(Amorphous resin segment other than polyester resin)
Amorphous resin segments other than polyester resins (hereinafter also simply referred to as “amorphous resin segments”) control the affinity between the amorphous resin constituting the binder resin and the hybrid crystalline polyester resin. It is a segment for. The presence of the amorphous resin segment improves the affinity between the hybrid crystalline polyester resin and the amorphous resin, making it easier for the hybrid crystalline polyester resin to be incorporated into the amorphous resin, and charging uniformity, etc. Can be improved.

  The amorphous resin segment is a portion derived from an amorphous resin other than the crystalline polyester resin. The presence of an amorphous resin segment in the hybrid crystalline polyester resin (and also in the toner) is confirmed by specifying the chemical structure using, for example, NMR measurement or methylation reaction P-GC / MS measurement. be able to.

The amorphous resin segment does not have a melting point and has a relatively high glass transition temperature (T _g ) when differential scanning calorimetry (DSC) is performed on a resin having the same chemical structure and molecular weight as the segment. Is a resin segment. At this time, for the resin having the same chemical structure and molecular weight as the segment, the glass transition temperature (T _g1 ) in the first temperature rising process in DSC measurement is preferably in the range of 30 to 80 ° C., particularly 40 It is preferable to be within a range of ˜65 ° C.

  The amorphous resin segment is not particularly limited as long as it is defined above. For example, for a resin having a structure in which other components are copolymerized on the main chain of an amorphous resin segment and a resin having a structure in which an amorphous resin segment is copolymerized on a main chain composed of other components, this resin is used. If the toner to be contained has an amorphous resin segment as described above, the resin corresponds to the hybrid crystalline polyester resin having an amorphous resin segment in the present invention.

  The amorphous resin segment is preferably composed of the same kind of resin as the amorphous resin contained in the binder resin (that is, the amorphous resin contained in the core particles). By adopting such a form, the affinity between the hybrid crystalline polyester resin and the amorphous resin is further improved, and the hybrid crystalline polyester resin is more easily incorporated into the amorphous resin, and charging uniformity, etc. Is further improved.

  Although the resin component which comprises an amorphous resin segment is not restrict | limited in particular, For example, a vinyl resin, a urethane resin, a urea resin etc. are mentioned. Among these, vinyl resin is preferable because it is easy to control thermoplasticity.

  The vinyl resin is not particularly limited as long as a vinyl compound is polymerized, and examples thereof include acrylic ester resins, styrene-acrylic ester resins, and ethylene-vinyl acetate resins. These may be used alone or in combination of two or more.

  Among the above vinyl resins, a styrene-acrylic ester resin (styrene-acrylic resin) is preferable in consideration of plasticity at the time of heat fixing. Therefore, below, the styrene-acrylic resin segment as an amorphous resin segment is demonstrated.

The styrene-acrylic resin segment is formed by addition polymerization of at least a styrene monomer and a (meth) acrylic acid ester monomer. The styrenic monomer herein includes those having a structure having a known side chain or functional group in the styrene structure in addition to styrene represented by the structural formula of CH ₂ ═CH—C ₆ H ₅ . In addition, the (meth) acrylic acid ester monomer here is an acrylic acid ester compound or a methacrylic acid ester derivative in addition to an acrylic acid ester compound or a methacrylic acid ester compound represented by CH ₂ = CHCOOR (R is an alkyl group). And the like, and ester compounds having a known side chain or functional group in the structure.

  Specific examples of the styrene monomer and (meth) acrylic acid ester monomer capable of forming a styrene-acrylic copolymer segment include aromatic vinyl monomers listed in the section “<Styrene-acrylic resin>”, Although a (meth) acrylic acid ester monomer can be used suitably, what can be used for formation of the styrene-acrylic copolymer segment used by this invention is not limited to these.

  The content of the amorphous resin segment is preferably in the range of 2 to 20% by mass with respect to the total amount of the hybrid crystalline polyester resin. Furthermore, the content is more preferably 4% by mass or more and less than 15% by mass, and further preferably 5 to 11% by mass. By setting it within the above range, sufficient crystallinity can be imparted to the hybrid crystalline polyester resin.

(Method for producing hybrid crystalline polyester resin)
The method for producing a hybrid resin according to the present invention is particularly limited as long as it is a method capable of forming a polymer having a structure in which the crystalline polyester resin segment and the amorphous resin segment are molecularly bonded. is not. For example, as a method for producing a hybrid resin, it is produced in the same manner as described later in “(Method for producing styrene-acryl-modified polyester resin)” except that a crystalline polyester resin segment is used instead of an amorphous polyester segment. be able to. In this case, other amorphous resin segments may be used instead of the styrene-acrylic polymer segments.

<Amorphous polyester resin>
Amorphous polyester resin has a glass transition temperature (T _g ) in an endothermic curve obtained by differential scanning calorimetry (DSC), but exhibits an amorphous property having no melting point, that is, no clear endothermic peak at elevated temperature. Polyester resin.
The amorphous polyester resin is not particularly limited as long as it is defined above. For example, the amorphous polyester resin itself may be contained, or a styrene-acryl-modified polyester resin described later may be contained.

The glass transition temperature of the amorphous polyester resin _{(T ga)} is preferably in the range of 53-63 ° C.. By being in this range, heat resistant storage stability and low temperature fixability can be further secured.

The main resin contained in the core particle is that the amorphous polyester resin is an amorphous polyester resin chemically bonded to a styrene-acrylic resin (hereinafter also referred to as “styrene-acrylic modified polyester resin”). This is preferable because the compatibility with (styrene-acrylic resin) can be improved, and the releasing effect at the time of fixing the core / shell toner and the strength of the image after fixing can be improved.
Here, the “styrene-acrylic modified polyester resin” is a structure in which the above styrene-acrylic resin segment is molecularly bonded to an amorphous polyester molecular chain (hereinafter also referred to as “amorphous polyester segment”). It is a resin (hybrid resin) composed of polyester molecules. That is, the styrene-acrylic modified polyester resin is a resin having a copolymer structure in which a styrene-acrylic resin segment is molecularly bonded to an amorphous polyester segment.

Moreover, the styrene-acryl modified polyester resin used as the amorphous polyester resin is clearly distinguished from the above-mentioned hybrid crystalline polyester resin in the following points. That is, the amorphous polyester segment constituting the amorphous styrene-acryl-modified polyester resin is different from the crystalline polyester resin segment constituting the hybrid crystalline polyester resin and does not have a clear melting point and is relatively high. An amorphous molecular chain having a glass transition temperature (T _g ). This can be confirmed by performing differential scanning calorimetry (DSC) on the toner. In addition, since the monomer (chemical structure) constituting the amorphous polyester segment is different from the monomer (chemical structure) constituting the crystalline polyester resin segment, it can also be distinguished by analysis such as NMR. Can do.

  The amorphous polyester segment is formed by a polyhydric alcohol component and a polyvalent carboxylic acid component.

The polyhydric alcohol component is not particularly limited, but is preferably an aromatic diol or a derivative thereof from the viewpoint of chargeability and toner strength. For example, bisphenols such as bisphenol A and bisphenol F, And alkylene oxide adducts of bisphenols such as these ethylene oxide adducts and propylene oxide adducts.
Among these, it is preferable to use an ethylene oxide adduct and a propylene oxide adduct of bisphenol A as the polyhydric alcohol component, particularly from the viewpoint of improving the charging uniformity of the toner. These polyhydric alcohol components may be used alone or in combination of two or more.

  The polyvalent carboxylic acid component to be condensed with the polyhydric alcohol component is not particularly limited. For example, terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid, Aromatic carboxylic acids such as fumaric acid, maleic anhydride, succinic acid, adipic acid, sebacic acid, alkenyl succinic acid and the like; and lower alkyl esters of these acids, acid anhydrides, etc. One or more of these can be used.

  The number average molecular weight (Mn) of the amorphous polyester resin is preferably in the range of 2000 to 10,000 from the viewpoint that the plasticity is easily controlled.

The glass transition temperature (T _g ) of the amorphous polyester resin is preferably in the range of 20 to 70 ° C. The glass transition temperature (T _g ) can be measured according to the method (DSC method) defined in ASTM (American Society for Testing and Materials) D3418-82. For the measurement, a DSC-7 differential scanning calorimeter (manufactured by PerkinElmer), a TAC7 / DX thermal analyzer controller (manufactured by PerkinElmer) or the like can be used.

  The method for forming the amorphous polyester segment is not particularly limited, and the polyvalent carboxylic acid and the polyhydric alcohol are polycondensed using a known esterification catalyst in the same manner as the method for forming the crystalline polyester resin described above ( Amorphous polyester segments can be formed by esterification.

  In the present invention, a shell is formed using particles of an amorphous polyester resin. In this shell, the shell can be contained together with a styrene-acryl-modified polyester resin within a range that does not impair the effects of the present invention. Examples of the resin include styrene-acrylic resin, polyester resin, and urethane resin.

  The content ratio of the styrene-acrylic modified polyester resin in the shell is preferably 70 to 100% by mass and more preferably 90 to 100% by mass in 100% by mass of the resin constituting the shell.

  When the content ratio of the styrene-acrylic modified polyester resin in the shell is 70% by mass or more, sufficient affinity between the core particles and the shell can be obtained, and a desired shell can be formed. In addition, it is possible to avoid the possibility that sufficient resistance to crushing cannot be obtained.

  And in this invention, the content rate (henceforth "styrene-acryl modification amount") of the styrene-acryl polymer segment in a styrene-acryl modification polyester resin shall be in the range of 5-30 mass%. In particular, it is preferably in the range of 5 to 20% by mass. Within this range, the compatibility with the main resin (styrene-acrylic resin) contained in the core particles can be improved, and as a result, the releasing effect during fixing of the core / shell toner, and the image after fixing The strength of can be further improved.

  Specifically, the amount of styrene-acryl modification is the total mass of the resin material used for synthesizing the styrene-acryl modification polyester resin, that is, the monomer constituting the unmodified polyester resin that becomes an amorphous polyester segment. , Aromatic vinyl monomer and (meth) acrylic monomer and (meth) acrylic acid ester monomer as a styrene-acrylic polymer segment and the total mass of both reactive monomers for bonding them, ) Refers to the mass ratio of the acrylic acid ester monomer.

When the amount of styrene-acrylic modification is in the above range, the affinity between the styrene-acrylic modified polyester resin and the core particles is appropriately controlled. Thereby, the fusion state of the interface between the styrene-acrylic modified polyester resin and the core particles and the fusion state of the styrene-acrylic modified polyester resins can be balanced appropriately. As a result, a shell film or film-like domain having excellent heat resistance and fixing property can be formed, and the surface of the toner base particles becomes smooth.
On the other hand, when the amount of styrene-acrylic modification is 5% by mass or more, a shell film or a film-like domain can be suitably formed. As a result, the fusion of the interface between the styrene-acrylic modified polyester resin and the core particles is insufficient. As a result, the problem that the toner is not sufficiently fused even when melted at the time of fixing can be avoided. For this reason, when the amount of styrene-acryl modification is 5% by mass or more, low-temperature fixability and document offset resistance can be sufficiently obtained, which is preferable.
Further, when the styrene-acryl modification amount is 30% by mass or less, the styrene-acryl modification polyester resin can be prevented from having a too high softening point, and sufficient low-temperature fixability can be obtained as a whole toner particle. preferable.

  The styrene-acrylic resin segment may be bonded to the terminal of the polyester main chain, or may be grafted as a side chain. However, the styrene-acrylic modified polyester resin in which the styrene-acrylic resin unit is bonded to the terminal of the polyester resin is easier to form the domains of the polyester resin unit and the styrene-acrylic resin unit. Therefore, the amorphous polyester segment is easily oriented on the toner surface layer in the aggregation / fusion process, and the styrene-acrylic resin segment is easily oriented in the core portion containing the styrene-acrylic resin. A shell structure can be formed.

The styrene-acrylic modified polyester resin constituting the shell has a glass transition temperature of 50 to 50 from the viewpoint of reliably obtaining fixing properties such as low-temperature fixing property and fixing separation property, and heat resistance such as heat-resistant storage property and blocking resistance. It is preferable that it is 70 degreeC, More preferably, it is 53-
It is preferably in the range of 63 ° C, and the softening point is preferably 80 to 120 ° C, more preferably 90 to 110 ° C. The glass transition temperature of the styrene-acryl-modified polyester resin is a value measured by a method (DSC method) defined in ASTM (American Society for Testing and Materials) D3418-82.

  When the content ratio of the amorphous polyester resin in the binder resin is excessively low, sufficient heat-resistant storage stability may not be obtained, and the content ratio of the amorphous polyester resin in the binder resin is excessively high. In such a case, sufficient low-temperature fixability may not be obtained.

(Method for producing styrene-acrylic modified polyester resin)
As a method for producing the styrene-acrylic modified polyester resin contained in the shell as described above, an existing general scheme can be used. As typical methods, the following four methods may be mentioned. Among them, the following method (A) is most preferable.

(A) The amorphous polyester segment is polymerized in advance, the reactive polyester is reacted with the amorphous polyester segment, and an aromatic vinyl monomer for forming a styrene-acrylic polymer segment and ( A method of forming a styrene-acrylic polymer segment by reacting a (meth) acrylic acid ester monomer.
(B) A polyvalent carboxylic acid monomer for polymerizing a styrene-acrylic polymer segment in advance, reacting the styrene-acrylic polymer segment with both reactive monomers, and forming an amorphous polyester segment; A method of forming an amorphous polyester segment by reacting a polyhydric alcohol monomer.
(C) A method in which an amorphous polyester segment and a styrene-acrylic polymer segment are respectively polymerized in advance, and then both reactive monomers are reacted with each other to bond them together.
(D) A method in which an amorphous polyester segment is polymerized in advance, and a styrene-acryl polymerizable monomer is added to the polymerizable unsaturated group of the amorphous polyester segment to bond them together.

  In addition, the amphoteric monomer described in (C) is a group capable of reacting with a polyvalent carboxylic acid monomer or a polyhydric alcohol monomer for forming an amorphous polyester segment of a styrene-acryl-modified polyester resin, and polymerization. It is a monomer having a polymerizable unsaturated group.

As a method of (A), specifically, for example,
(1) a mixing step of mixing an unmodified polyester resin, an aromatic vinyl monomer and a (meth) acrylic acid ester monomer, and a bireactive monomer;
(2) a polymerization step of polymerizing an aromatic vinyl monomer and a (meth) acrylic acid ester monomer;
It is possible to pass through. Thereby, the styrene-acrylic polymer segment can be bonded to the amorphous polyester segment.

  When the mixing step (1) and the polymerization step (2) are performed, the terminal hydroxyl group of the amorphous polyester segment and the carboxy group of the both reactive monomers form an ester bond, and the vinyl of the both reactive monomers. The styrene-acrylic polymer segment is bonded by bonding the group to the vinyl group of the aromatic vinyl monomer or the (meth) acrylic acid monomer.

In the mixing step (1), it is preferable to heat. The heating temperature may be a range in which an unmodified polyester resin, aromatic vinyl monomer, (meth) acrylic acid ester monomer and amount-reactive monomer can be mixed, and good mixing is obtained. Since polymerization control becomes easy, it can be set to 80-120 degreeC, for example, More preferably, it is 85-115 degreeC, More preferably, it is 90-110 degreeC.

  Among unmodified polyester resin, aromatic vinyl monomer, (meth) acrylic acid ester monomer and both reactive monomers, the proportion of aromatic vinyl monomer and (meth) acrylic acid ester monomer used is the resin used The total mass of the material, that is, the total proportion of the aromatic vinyl monomer and the (meth) acrylic acid ester monomer when the total mass of the above four members is 100 mass% is set within the range of 5 to 30 mass%. In particular, it is preferable to be in the range of 5 to 20% by mass.

Affinity between the styrene-acryl-modified polyester resin and the core particles is appropriate because the total ratio of the aromatic vinyl monomer and the (meth) acrylic acid ester monomer to the total mass of the resin material used is within the above range. Therefore, a favorable shell can be formed, which is preferable because the releasing effect at the time of fixing and the strength of the image after fixing can be improved.
Moreover, when the said ratio is 5 mass% or more, the obtained styrene-acryl modified polyester resin can form a favorable shell, and as a result, it can avoid that a core particle is exposed too much. A sufficient heat-resistant storage property and charging property can be obtained for the toner.
Further, when the ratio is within 30% by mass, the resulting styrene-acryl-modified polyester resin does not have a too high softening point, and as a result, the obtained toner achieves sufficient low-temperature fixability as a whole. it can.

The relative proportions of aromatic vinyl monomers and (meth) acrylic acid ester monomer has a glass transition temperature calculated by the FOX equation represented by the following formula (A) (T _g) is 35 to 80 ° C. The ratio is preferably in the range of 40 to 60 ° C.

Formula (A): 1 / T _g = Σ (Wx / T _gx )
(In formula (a), Wx is the mass fraction of monomer x, and T _gx is the glass transition temperature of the homopolymer of monomer x.)
In the present specification, both reactive monomers are not used for the calculation of the glass transition temperature.

  Among unmodified polyester resin, aromatic vinyl monomer, (meth) acrylic acid ester monomer, and both reactive monomers, the proportion of both reactive monomers used is the total mass of the resin material used, that is, the above four factors The ratio of the two reactive monomers when the total mass of is 100% by mass is 0.1% by mass or more and 10.0% by mass or less, and particularly 0.5% by mass or more and 3.0% by mass or less. It is preferable.

(Aromatic vinyl monomers and (meth) acrylic acid ester monomers)
The aromatic vinyl monomer and (meth) acrylic acid ester monomer for forming the styrene-acrylic polymer segment have an ethylenically unsaturated bond capable of radical polymerization.

As the aromatic vinyl monomer, those described in the above-mentioned “<styrene-acrylic resin>” can be used.
These aromatic vinyl monomers can be used alone or in combination of two or more.

As the (meth) acrylic acid ester monomer, those described in the above-mentioned “<styrene-acrylic resin>” can be used. These (meth) acrylic acid ester monomers can be used alone or in combination of two or more.

  As an aromatic vinyl monomer and (meth) acrylic acid ester monomer for forming a styrene-acrylic polymer segment, styrene or a derivative thereof is often used from the viewpoint of obtaining excellent chargeability and image quality characteristics. preferable. Specifically, the amount of styrene or a derivative thereof used is 50% by mass in all monomers (aromatic vinyl monomer and (meth) acrylic acid ester monomer) used to form a styrene-acrylic polymer segment. The above is preferable.

(Amotropic monomer)
As the bi-reactive monomer for forming the styrene-acrylic polymer segment, a group capable of reacting with the polyvalent carboxylic acid monomer and / or the polyhydric alcohol monomer for forming the amorphous polyester segment and polymerizable unsaturated As long as the monomer has a group, specifically, for example, acrylic acid, methacrylic acid, fumaric acid, maleic acid, maleic anhydride, and the like can be used. In the present invention, it is preferable to use acrylic acid and methacrylic acid as both reactive monomers.

(Polyester resin for producing styrene-acrylic modified polyester resin)
The polyester resin used for producing the styrene-acrylic modified polyester resin according to the present invention is obtained by polycondensation reaction in the presence of an appropriate catalyst using a polyvalent carboxylic acid monomer (derivative) and a polyhydric alcohol monomer (derivative) as raw materials. It is manufactured.

  As polyvalent carboxylic acid monomer derivatives, alkyl esters, acid anhydrides and acid chlorides of polyvalent carboxylic acid monomers can be used. As polyhydric alcohol monomer derivatives, ester compounds of polyhydric alcohol monomers and hydroxycarboxylic acids are used. Can be used.

  Examples of the polyvalent carboxylic acid monomer include aliphatic dicarboxylic acids and aromatic dicarboxylic acids described in the above-mentioned “<crystalline polyester resin>”, and those described in paragraphs 0086 and 0087 of JP2012-255957A. Can be used.

  As the polyhydric alcohol monomer, for example, the aliphatic diol described in the above-mentioned “<Crystalline polyester resin>” or the one described in paragraph 0091 of JP2012-255957A can be used.

  The ratio of the polyhydric carboxylic acid monomer to the polyhydric alcohol monomer is such that the equivalent ratio [OH] / [COOH] of the hydroxy group [OH] of the polyhydric alcohol monomer and the carboxy group [COOH] of the polyhydric carboxylic acid is Preferably it is 1.5 / 1-1 / 1.5, More preferably, it is 1.2 / 1-1 / 1.2.

  As the catalyst for synthesizing the polyester resin, various conventionally known catalysts can be used.

  The unmodified polyester resin for obtaining the styrene-acrylic modified polyester resin preferably has a glass transition temperature in the range of 40 to 70 ° C, more preferably in the range of 50 to 65 ° C. When the glass transition temperature of the unmodified polyester resin is 40 ° C. or higher, the cohesive force in the high temperature region becomes appropriate for the polyester resin, and the occurrence of hot offset phenomenon during fixing is suppressed. Further, when the glass transition temperature of the unmodified polyester resin is 70 ° C. or less, sufficient melting can be obtained at the time of fixing, and a sufficient minimum fixing temperature can be ensured.

  Moreover, it is preferable that the weight average molecular weights (Mw) of the said unmodified polyester resin are 1500 or more and 60000 or less, More preferably, it exists in the range of 3000-40000. When the weight average molecular weight is 1500 or more, a cohesive force suitable for the entire binder resin is obtained, and the occurrence of a hot offset phenomenon during fixing is suppressed. Further, when the weight average molecular weight is 60000 or less, it is possible to obtain a sufficient melting and secure a minimum fixing temperature, while suppressing the occurrence of a hot offset phenomenon during fixing.

  The unmodified polyester resin may have a partially branched structure or a crosslinked structure, for example, by selecting a carboxylic acid valence or an alcohol valence as a polyvalent carboxylic acid monomer or a polyhydric alcohol monomer to be used. Good.

(Polymerization initiator)
In the polymerization step of polymerizing the aromatic vinyl monomer and the (meth) acrylic acid ester monomer, the polymerization is preferably performed in the presence of a radical polymerization initiator, and the timing of adding the radical polymerization initiator is not particularly limited. In view of easy control of radical polymerization, it is preferably added after the mixing step.

  Various known polymerization initiators are preferably used as the polymerization initiator. Specifically, for example, hydrogen peroxide, acetyl peroxide, cumyl peroxide, -tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, Lauroyl peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, di-t-butyl peroxide, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetic acid-tert Hydroperoxide, tert-butyl performate, tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, per-N- (3-toluyl) Palmitic acid-ter -Peroxides such as butyl; 2,2'-azobis (2-aminodipropane) hydrochloride, 2,2'-azobis- (2-aminodipropane) nitrate, 1,1'-azobis (1- Azo compounds such as methylbutyronitrile-3-sodium sulfonate), 4,4′-azobis-4-cyanovaleric acid, poly (tetraethylene glycol-2,2′-azobisisobutyrate), and the like. .

(Chain transfer agent)
In the polymerization step of polymerizing the aromatic vinyl monomer and the (meth) acrylic acid ester monomer, a commonly used chain transfer agent is used for the purpose of adjusting the molecular weight of the styrene-acrylic polymer segment. be able to. The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as octyl mercaptan, dodecyl mercaptan, alkyl mercaptan, t-dodecyl mercaptan; n-octyl-3-mercaptopropionate, stearyl-3-mercaptopropioate. Mercaptopropionic acid such as nate, mercapto fatty acid ester and styrene dimer can be used. These can be used alone or in combination of two or more.

  The addition amount of the chain transfer agent varies depending on the molecular weight and molecular weight distribution of the desired styrene-acrylic polymer segment. Specifically, the aromatic vinyl monomer, the (meth) acrylic acid ester monomer, and the both reactive monomers are used. It is preferable to add within a range of 0.1 to 5% by mass with respect to the total amount.

The polymerization temperature in the polymerization step for polymerizing the aromatic vinyl monomer and the (meth) acrylate monomer is not particularly limited, and the polymerization between the aromatic vinyl monomer and the (meth) acrylate monomer and the polyester resin is performed. In the range in which the coupling | bonding advances, it can select suitably. For example, the polymerization temperature is preferably in the range of 85 to 125, more preferably in the range of 90 to 120 ° C, and still more preferably in the range of 95 to 115 ° C.

  In the production of the styrene-acrylic modified polyester resin, it is practically preferable that volatile organic substances from the emulsion such as the amount of residual monomer after the polymerization step are suppressed to 1000 ppm or less, more preferably 500 ppm or less, and still more preferably. 200 ppm or less.

<Release agent (wax)>
The release agent according to the present invention is not particularly limited, and known ones can be used. Specifically, for example, polyolefin wax such as polyethylene wax and polypropylene wax, branched chain hydrocarbon wax such as microcrystalline wax, long chain hydrocarbon wax such as paraffin wax and sazol wax, distearyl ketone, etc. Dialkyl ketone wax, carnauba wax, montan wax, behenate behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerol tribehenate, 1,18-octadecane Ester wax such as diol distearate, tristearyl trimellitic acid, distearyl maleate, ethylenediamine behenyl amide, tristearyl amide of trimellitic acid And the like amide-based waxes such as.

  Melting | fusing point of a mold release agent becomes like this. Preferably it is 40-160 degreeC, More preferably, it is 50-120 degreeC. By setting the melting point within the above range, heat-resistant storage stability of the toner is ensured, and stable toner image formation can be performed without causing cold offset or the like even when fixing at a low temperature. Further, the content of the release agent in the toner is preferably 1 to 30% by mass, more preferably 5 to 20% by mass.

<Colorant>
As the colorant according to the present invention, carbon black, a magnetic substance, a dye, a pigment, and the like can be arbitrarily used. As the carbon black, channel black, furnace black, acetylene black, thermal black, lamp black, and the like are used. The Magnetic materials include ferromagnetic metals such as iron, nickel and cobalt, alloys containing these metals, compounds of ferromagnetic metals such as ferrite and magnetite, alloys that do not contain ferromagnetic metals but exhibit ferromagnetism by heat treatment, For example, a kind of alloy called Heusler alloy such as manganese-copper-aluminum and manganese-copper-tin, chromium dioxide, and the like can be used.

  Examples of the black colorant include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.

  Examples of the colorant for magenta or red include C.I. I. Pigment Red 2, 3, 5, 6, 7, 15, 15, 48: 1, 53: 1, 57: 1, 60, 63, 64, 68, the same 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 139, 144, 149, 150, 163, 166, 170, 177, 178, 184, 202, 206, 207, 209, 222, 238, 269, and the like.

Examples of the colorant for orange or yellow include C.I. I. Pigment orange 31,
43, C.I. I. Pigment yellow 12, 14, 15, 17, 74, 83, 93, 94, 138, 155, 162, 180, 185, and the like.

  Further, as a colorant for green or cyan, C.I. I. Pigment Blue 2, 3, 15, 15, 15: 2, 15: 3, 15: 4, 16, 17, 17, 60, 62, 66, C.I. I. And CI Pigment Green 7.

  These colorants can be used alone or in combination of two or more as required.

  The addition amount of the colorant is preferably in the range of 1 to 30% by mass, more preferably in the range of 2 to 20% by mass with respect to the total toner, and a mixture thereof can also be used. Within such a range, the color reproducibility of the image can be ensured.

  The size of the colorant is a volume average particle size, for example, in the range of 10 to 1000 nm, preferably in the range of 50 to 500 nm, and more preferably in the range of 80 to 300 nm.

[Other ingredients]
The toner base particles of the present invention may contain, in addition to the above components, internal additives such as a charge control agent; and external additives such as inorganic fine particles, organic fine particles, and a lubricant. .

<Charge control agent>
As the charge control agent, various known compounds such as nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, and salicylic acid metal salts can be used. .

  The addition amount of the charge control agent is usually 0.1 to 10% by mass, preferably 0.5 to 5% by mass with respect to 100% by mass of the binder resin in the finally obtained toner base particles. The

  The size of the charge control agent particles is, for example, 10 to 1000 nm, preferably 50 to 500 nm, more preferably 80 to 300 nm in terms of number average primary particle diameter.

(External additive)
From the viewpoint of improving the charging performance, fluidity, and cleaning properties of the toner, particles such as known inorganic fine particles and organic fine particles and a lubricant can be added as external additives to the surface of the toner base particles.

Preferred inorganic fine particles include inorganic fine particles made of silica, titania, alumina, strontium titanate, or the like.
If necessary, these inorganic fine particles may be hydrophobized.

  As the organic fine particles, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. Specifically, homopolymers such as styrene and methyl methacrylate and organic fine particles made of these copolymers can be used.

The lubricant is used for the purpose of further improving the cleaning property and the transfer property. Examples of the lubricant include zinc stearate, salts of aluminum, copper, magnesium, calcium, and zinc oleate. Of higher fatty acids, such as salts of manganese, iron, copper, magnesium, zinc of palmitic acid, salts of copper, magnesium, calcium, zinc of linoleic acid, salts of calcium, zinc of ricinoleic acid, salts of calcium, etc. Metal salts are mentioned. Various combinations of these external additives may be used.

  The addition amount of the external additive is preferably 0.1 to 10.0% by mass with respect to 100% by mass of the toner base particles.

  Examples of the method of adding the external additive include a method of adding using various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.

<< Step I to Step VI >>
Hereinafter, Step I to Step VI in the method for producing an electrostatic charge image developing toner of the present invention will be described.

<Process I>
In Step I, a flocculant is added with stirring to a dispersion liquid mixture containing at least the styrene-acrylic resin and the release agent.
The dispersion mixture is prepared by a method in which a styrene-acrylic resin fine particle dispersion containing styrene-acrylic resin fine particles and a colorant fine particle dispersion containing colorant fine particles are mixed in an aqueous medium. Is preferred.

In addition, when the styrene-acrylic resin fine particles do not contain a release agent, it is preferable to further mix the release agent fine particle dispersion.
Further, in the case where the toner base particles contain other internal additives in addition to the release agent, the fine particles of the amorphous polyester resin may contain the internal additives. Alternatively, a dispersion of the internal additive fine particles composed solely of the internal additive may be separately prepared, and the internal additive fine particle dispersion may be added before or after the flocculant is added. In addition, when adding after adding a coagulant | flocculant, it is preferable before addition of the dispersion liquid of the crystalline polyester resin in the process II is completed.

  The styrene-acrylic resin fine particle dispersion, the colorant fine particle dispersion, and the release agent fine particle dispersion are prepared as follows.

(Preparation of styrene-acrylic resin fine particle dispersion)
The styrene-acrylic resin fine particle dispersion is prepared by synthesizing a styrene-acrylic resin and dispersing the styrene-acrylic resin in a fine particle form in an aqueous medium.

  Since the manufacturing method of a styrene-acrylic resin is as above-mentioned, detailed description is abbreviate | omitted. In addition, what is necessary is just to add a mold release agent when superposing | polymerizing a styrene-acrylic resin, when making a styrene-acrylic resin microparticle contain a mold release agent. In this case, a miniemulsion polymerization method is preferably used as the polymerization method.

  As a method of dispersing the styrene-acrylic resin in the aqueous medium, a method of forming an aqueous dispersion of the styrene-acrylic resin fine particles by forming styrene-acrylic resin fine particles from a monomer for obtaining a styrene-acrylic resin (i ) Or styrene-acrylic resin is dissolved or dispersed in an organic solvent (solvent) to prepare an oil phase liquid, and the oil phase liquid is dispersed in an aqueous medium by phase inversion emulsification to obtain a desired particle size. Examples include a method (ii) of removing an organic solvent (solvent) after forming oil droplets in a controlled state.

In the present invention, the “aqueous medium” refers to a medium containing at least 50% by mass of water, and examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol. , Butanol, acetone, methyl ethyl ketone, dimethylformamide, methyl cellosolve, tetrahydrofuran and the like. Among these, it is preferable to use an organic organic solvent such as methanol, ethanol, isopropanol, and butanol, which is an organic solvent that does not dissolve the resin. Preferably, only water such as ion exchange water is used as the aqueous medium.

  In the method (i), first, a monomer for obtaining a styrene-acrylic resin is added to an aqueous medium together with a polymerization initiator and polymerized to obtain basic particles. Next, a method in which a radical polymerizable monomer and a polymerization initiator for obtaining a styrene-acrylic resin are added to the dispersion in which the basic particles are dispersed, and the radical polymerizable monomer is seed-polymerized to the basic particles. It is preferable to use it.

  At this time, a water-soluble polymerization initiator can be used as the polymerization initiator. As the water-soluble polymerization initiator, for example, a water-soluble radical polymerization initiator such as potassium persulfate or ammonium persulfate can be preferably used.

  Moreover, the above-mentioned chain transfer agent can be used in the seed polymerization reaction system for obtaining styrene-acrylic resin fine particles for the purpose of adjusting the molecular weight of the styrene-acrylic resin. The chain transfer agent is preferably mixed with the resin material in the mixing step.

  In the method (ii), the organic solvent (solvent) used for the preparation of the oil phase liquid has a low boiling point and is soluble in water from the viewpoint of easy removal after the formation of oil droplets. Low ones are preferred, and specific examples include methyl acetate, ethyl acetate, methyl ethyl ketone, isopropyl alcohol, methyl isobutyl ketone, toluene, xylene and the like. These can be used alone or in combination of two or more.

  The amount of the organic solvent (solvent) used (when two or more types are used, the total amount used) is usually within the range of 10 to 500 parts by weight, preferably 100 to 450 parts by weight with respect to 100 parts by weight of the styrene-acrylic resin. In the range of 200 parts by weight, more preferably in the range of 200-400 parts by weight.

  The amount of the aqueous medium used is preferably in the range of 50 to 2000 parts by mass and more preferably in the range of 100 to 1000 parts by mass with respect to 100 parts by mass of the oil phase liquid. By making the usage-amount of an aqueous medium into the said range, an oil phase liquid can be emulsified and disperse | distributed to a desired particle size in an aqueous medium.

  Further, a dispersion stabilizer may be dissolved in the aqueous medium, and a surfactant or resin fine particles may be added for the purpose of improving the dispersion stability of the oil droplets.

  As the dispersion stabilizer, a known one can be used. For example, it is preferable to use one that is soluble in acid or alkali, such as tricalcium phosphate, or from an environmental point of view, it may be an enzyme. It is preferable to use a decomposable one.

  As the surfactant, known anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants can be used.

  Examples of the resin fine particles for improving dispersion stability include polymethyl methacrylate resin fine particles, polystyrene resin fine particles, and polystyrene-acrylonitrile resin fine particles.

  Further, such emulsification dispersion of the oil phase liquid can be performed using mechanical energy, and the disperser for performing the emulsification dispersion is not particularly limited, and is a homogenizer, a low-speed shearing dispersion. And high-speed shearing dispersers, friction dispersers, high-pressure jet dispersers, ultrasonic dispersers, high-pressure impact dispersers and optimizers.

  Removal of the organic solvent after the formation of oil droplets is performed by gradually heating the entire dispersion liquid in which styrene-acrylic resin fine particles are dispersed in an aqueous medium in a stirring state, and giving strong stirring in a certain temperature range. Then, it can be performed by an operation such as desolvation. Alternatively, it can be removed while reducing the pressure using an apparatus such as an evaporator.

  The particle diameter of the styrene-acrylic resin fine particles (oil droplets) in the styrene-acrylic resin fine particle dispersion prepared by the method (i) or (ii) is a volume average particle diameter, and is in the range of 60 to 1000 nm. Preferably, it is in the range of 80 to 500 nm. The volume average particle diameter of the oil droplets can be controlled by the magnitude of mechanical energy during emulsification dispersion.

  Further, the content of the styrene-acrylic resin fine particles in the styrene-acrylic resin fine particle dispersion is preferably in the range of 5 to 50% by mass, and more preferably in the range of 10 to 30% by mass. Within such a range, the spread of the particle size distribution can be suppressed and the toner characteristics can be improved.

(Preparation of colorant fine particle dispersion)
The colorant fine particle dispersion is prepared by dispersing the colorant in the form of fine particles in an aqueous medium.

  The aqueous medium is as described in the above section “(Preparation of styrene-acrylic resin fine particle dispersion)”. In this aqueous medium, surfactants, resin fine particles, etc. are used for the purpose of improving dispersion stability. May be added.

  The dispersion of the colorant can be performed using mechanical energy, and such a disperser is not particularly limited, and is described in the above section “(Preparation of styrene-acrylic resin fine particle dispersion)”. What was demonstrated in can be used.

  The content of the colorant fine particles in the colorant fine particle dispersion is preferably in the range of 10 to 50% by mass, and more preferably in the range of 15 to 40% by mass. Within such a range, there is an effect of ensuring color reproducibility.

(Preparation of release agent fine particle dispersion)
The release agent fine particle dispersion is prepared by dispersing the release agent in the form of fine particles in an aqueous medium.

  The aqueous medium is as described in the above section “(Preparation of styrene-acrylic resin fine particle dispersion)”. In this aqueous medium, surfactants, resin fine particles, etc. are used for the purpose of improving dispersion stability. May be added.

  The release agent can be dispersed using mechanical energy, and such a disperser is not particularly limited, and the above-mentioned "(Preparation of styrene-acrylic resin fine particle dispersion)" Those described in the section can be used.

  The content of the release agent fine particles in the release agent fine particle dispersion is preferably in the range of 10 to 50% by mass, and more preferably in the range of 15 to 40% by mass. Within such a range, effects of preventing hot offset and ensuring separability can be obtained.

(Flocculant)
The flocculant is not particularly limited, but a flocculant selected from metal salts is preferably used. For example, monovalent metal salts such as alkali metal salts such as sodium, potassium and lithium, for example, divalent metal salts such as calcium, magnesium, manganese and copper, and trivalent metals such as iron and aluminum. There is salt. Specific examples of the salt include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, and manganese sulfate. Among these, divalent metal is particularly preferable. Salt. When a divalent metal salt is used, agglomeration can be promoted with a smaller amount. These flocculants can be used alone or in combination of two or more.

  In step I, it is preferable that the standing time (time until heating is started) to be left after adding the flocculant is as short as possible. That is, after adding the flocculant in step I, it is preferable to start step II as soon as possible, so that it is equal to or higher than the melting point of the crystalline polyester resin and the glass transition temperature of the styrene-acrylic resin. The reason for this is not clear, but the agglomeration state of the particles fluctuates with the passage of the standing time, and the particle size distribution of the obtained toner base particles becomes unstable or the surface property fluctuates. It is because there is a possibility of doing. The standing time is usually within 30 minutes, preferably within 10 minutes. The temperature at which the flocculant is added is preferably not higher than the glass transition temperature of the styrene-acrylic resin, and more preferably at room temperature.

<Process II>
In Step II, a dispersion of a crystalline polyester resin is added to the dispersion mixture to which the flocculant has been added in Step I, and at least the styrene-acrylic resin, the release agent, and the crystallinity under heating and stirring. The polyester resin is agglomerated and united to obtain a dispersion of core particles.

  As described above, after adding the flocculant in step I, step II is preferably performed immediately. The heating rate in step II is preferably 0.8 ° C./min or more. The upper limit of the heating rate is not particularly limited, but is preferably 15 ° C./min or less from the viewpoint of suppressing the generation of coarse particles due to rapid progress of fusion. The liquid mixture prepared in Step I is at or above the glass transition temperature of the styrene-acrylic resin, preferably until the aggregation temperature is within a temperature range of −10 to + 10 ° C. relative to the melting point of the crystalline polyester resin. The mixture is warmed. Thereby, the styrene-acrylic resin fine particles and the colorant fine particles are aggregated as the temperature rises, and an aggregate is formed.

  Aggregation and coalescence are preferably performed by appropriately adjusting the number of agitation, such as by lowering the agitation speed of the dispersion mixture to which the dispersion of the crystalline polyester resin is added. Thereby, the repulsion by collision of particles can be suppressed, particles can be made to contact suitably and aggregation of particles can be advanced. The temperature at this time is preferably higher than the melting point of the crystalline polyester resin. The aggregation of the crystalline polyester resin fine particles, the styrene-acrylic resin fine particles and the colorant fine particles is advanced by appropriately adjusting the number of stirrings, such as by lowering the stirring speed while maintaining the temperature of the mixed liquid, and the aggregated particles When the diameter reaches a desired value, after cooling in the step III described later, a salt such as an aqueous sodium chloride solution is added as an aggregation terminator to stop aggregation. The particle size of the aggregated particles at this time is preferably such that the volume-based median diameter is in the range of 4.5 to 7.0 μm. The volume-based median diameter of the aggregated particles can be obtained by measuring the volume-based median diameter with “Coulter Multisizer 3” (manufactured by Beckman Coulter, Inc.).

(Preparation of crystalline polyester resin dispersion)
The crystalline polyester resin dispersion is prepared by synthesizing a crystalline polyester resin and dispersing the crystalline polyester resin in the form of fine particles in an aqueous medium. Therefore, hereinafter, the crystalline polyester resin dispersion is also referred to as crystalline polyester resin fine particle dispersion.

Since the manufacturing method of crystalline polyester resin is as above-mentioned, detailed description is abbreviate | omitted. Also, the number of carbon atoms C _acid with carbon number C _alcohol and polyvalent carboxylic acid component of a polyhydric alcohol component constituting the crystalline polyester resin is preferably one which satisfies the relational expression (A).

  The crystalline polyester resin fine particle dispersion is, for example, a method of performing dispersion treatment in an aqueous medium without using a solvent, or a solvent such as ethyl acetate, methyl ethyl ketone, toluene, and a general-purpose alcohol having a boiling point of less than 100 ° C. And a method of performing a solvent removal treatment after emulsifying and dispersing the solution in an aqueous medium using a disperser.

  The crystalline polyester resin may contain a carboxy group. In such a case, ammonia, sodium hydroxide, or the like may be added in order to ion-separate the carboxy group contained in the crystalline polyester resin and stably emulsify it in the aqueous phase to facilitate the emulsification smoothly.

  Furthermore, a dispersion stabilizer may be dissolved in the aqueous medium, and a surfactant or resin fine particles may be added for the purpose of improving the dispersion stability of the oil droplets. As the dispersion stabilizer, the surfactant and the resin fine particles, those described in the above section “(Preparation of styrene-acrylic resin fine particle dispersion)” can be used.

  The dispersion treatment can be performed using mechanical energy, and as the disperser, the one described in the above section “(Preparation of styrene-acrylic resin fine particle dispersion)” can be used.

  The particle size of the crystalline polyester resin fine particles (oil droplets) in the prepared crystalline polyester resin fine particle dispersion is preferably a volume average particle size in the range of 50 to 1000 nm, more preferably It is in the range of 50 to 500 nm, more preferably in the range of 80 to 500 nm. The volume average particle diameter of the oil droplets can be controlled by the magnitude of mechanical energy during emulsification dispersion.

  Further, the content of the crystalline polyester resin fine particles in the crystalline polyester resin fine particle dispersion is preferably within a range of 10 to 50% by mass with respect to 100% by mass of the dispersion, and within a range of 15 to 40% by mass. Is more preferable. Within such a range, the spread of the particle size distribution can be suppressed and the toner characteristics can be improved.

<Process III>
In Step III, the dispersion of the core particles obtained in Step II is cooled to a temperature of at least a crystallization peak temperature (T _qc ) of −15 ° C. of the crystalline polyester resin.
By setting the above temperature to the upper limit of cooling in the step III, the crystallization of the polyester resin becomes sufficient, so that the core particle internal structure is appropriately fixed. Thereby, even after passing through the process of adding and aggregating the shell particles in Step IV to Step V, the orientation to the amorphous polyester resin that is the shell particles does not occur as much as possible. It is thought that the membranous domain of the shell can be formed.
The lower limit of the cooling temperature in step III may be, for example, 30 ° C. or less. However, even if the temperature is further lowered, the subsequent steps are not greatly affected, and the amount of heat is excessively exchanged. It is preferable to set it as 30 degreeC or more from the surface.
The cooling rate is not particularly limited, but is preferably in the range of 0.2 to 20 ° C./min.
0-10 degree-C / min is more preferable. It is considered that the internal structure of the core particle and the shape of the core particle accompanying the crystallization of the crystalline polyester resin in the core particle can be appropriately set within the above cooling rate range.
When the temperature is 0.2 ° C./min or more, the core particle shape can be prevented from being deformed during the crystallization process of the crystalline polyester resin, and a desired toner shape can be obtained.
If it is 20 degrees C / min or less, a crystalline polyester resin will fully crystallize. For this reason, it can avoid that a compatible site | part with an amorphous polyester resin increases too much in the unification process of a shell by the process V mentioned later, and, as a result, a shell film | membrane or a domain on a film | membrane can be formed suitably. The cooling method is not particularly limited, and a method of cooling by introducing a refrigerant from the outside of the reaction vessel, or a method of cooling by directly introducing cold water into the reaction system can be used.

<Process IV>
The temperature of the dispersion of the core particles cooled in step III is
(1) At least the temperature below the melting point (T _mc ) of the crystalline polyester resin,
(2) The glass transition temperature (T _gs ) of the styrene-acrylic resin + 5 ° C. or higher.
(3) the amorphous polyester glass transition temperature of the resin _(T ga) + 3 ° C. and below temperatures and ₍₄₎ the _{T gs} <temperature satisfies the relationship T ga _{<T qc,}
The amorphous polyester resin particle dispersion is added to the core particle dispersion, and the amorphous polyester resin particles are adhered to the surface of the core particles as shell particles. obtain.

As mentioned above,
(5) The glass transition temperature (T _gs ) of the styrene-acrylic resin is in the range of 35 to 50 ° C.,
(6) Glass transition temperature of the amorphous polyester resin _{(T ga)} is in the range of 53-63 ° C.,
(7) It is preferable that melting | fusing point ( _Tmc ) of the said crystalline polyester resin exists in the range of 65-80 degreeC.
Within such a temperature range, low temperature fixability, heat resistant storage stability, heat resistance and plasticizing effect at the time of fixing can be further improved, which is preferable.

In Step IV, the pH of the dispersion of the core particles at 25 ° C. (pH _A ) and the pH of the dispersion of the amorphous polyester resin particles before addition to the dispersion of the core particles at 25 ° C. (pH _B) and, it is preferable to satisfy the relation given by the following formula (a) ~ (c).

Formula (a) 3 ≦ pH _A −pH _B
Formula (b) 7 ≦ pH _A ≦ 10
Formula (c) 2 ≦ pH _B ≦ 5

By performing the pH condition within the range described in the above formulas (a) to (c), uniform aggregation of the shell particles (amorphous polyester resin particles) can be promoted, and the core particle surface can be coated. Since the shell particles are more cohesive due to the difference between the shell particle size and the core particle size, dissociation of carboxy groups on the core particle surface can be achieved by adjusting the pH (pH _A ) of the core particle dispersion higher. By increasing the agglomeration property and adjusting the pH (pH _B ) of the shell particles to be low, aggregation to the core particles can be caused while suppressing the aggregation (homogeneous aggregation) between the shell particles.
In addition, when controlling the aggregation speed | rate to the core particle of the shell particle | grains after addition, adjustment of the number of stirring, temperature rising / falling operation within the temperature as described in (1)-(7) mentioned above, mentioned above. You may further add the pH adjuster which can be used in order to make pH conditions into the range as described in said formula (a)-(c).
Such a pH adjuster is not particularly limited as long as both acid and alkali are soluble in water. Specifically, the following are mentioned, for example.
Examples of the alkali include inorganic bases such as sodium hydroxide and potassium hydroxide, and ammonia.
Examples of the acid include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid and boric acid, sulfonic acid acetic acids such as methanesulfonic acid, ethanesulfonic acid and benzenesulfonic acid, and carboxylic acids such as citric acid and formic acid.

The volume average particle size of the amorphous polyester resin particles in the dispersion of the amorphous polyester resin particles added in Step IV is preferably in the range of 50 to 300 nm.
If the volume average particle diameter of the amorphous polyester resin particles is in the range of 50 to 300 nm, the adhesion state of the shell can be made uniform, and the coverage can be secured with a smaller amount of shell. Further, if the thickness is 50 nm or more, aggregation of shell particles can be avoided, and if the thickness is 300 nm or less, the coating can be sufficiently performed. Can be avoided.

(PH measurement)
The pH (pH _A ) of the core particle dispersion at 25 ° C. and the pH (pH _B ) of the amorphous polyester resin particle dispersion at 25 ° C. before being added to the core particle dispersion are as follows: It was measured.
Glass electrode type hydrogen ion concentration indicator; HM-20P (manufactured by Toago DKK); reference electrode internal solution; RE-4, phthalic acid standard solution (pH 4.01, 25 ° C.), neutral phosphate standard solution (PH 6.86, 25 ° C.) and borate standard solution (pH 9.18, 25 ° C.), and then added to the core particle dispersion at 25 ° C. and the core particle dispersion. The pH of the previous amorphous polyester resin particle dispersion was measured.

<Process V>
In step V, the core-shell particle dispersion is adjusted to a glass transition temperature (T _ga ) + 3 ° C. of the amorphous polyester resin and a temperature not higher than the melting point (T _mc ) of the crystalline polyester resin, The core particles, the shell particles, and the shell particles are fused together to obtain a core / shell type toner base particle dispersion.

<Process VI>
In step VI, the core / shell toner base particle dispersion obtained in step V is cooled, and then the core / shell toner base particle is separated from the core / shell toner base particle dispersion and dried.

The separation method is not particularly limited as long as the core / shell toner base particles can be separated from the core / shell toner base particle dispersion, and a known method can be used.
Specifically, for example, separation (separation) may be performed by filtration. Examples of the filtration method include, but are not limited to, a centrifugal separation method, a vacuum filtration method using Nutsche and the like, a filtration method using a filter press and the like.

  Then, if necessary, the separated core-shell type toner base particles may be washed. For example, deposits such as a surfactant and an aggregating agent may be removed by washing from the core / shell toner base particles (cake-like aggregates) separated by filtration. The washing is preferably performed with water washing until the electric conductivity of the filtrate reaches a level within a range of 1 to 10 μS / cm, for example.

  The drying is applied to the separated core / shell toner base particles. The drying method is not particularly limited, and for example, a method using a dryer may be used. Specific examples of the dryer include known dryers such as spray dryers, vacuum freeze dryers, and vacuum dryers, stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, and rotary dryers. It is also possible to use a drier, a stirring drier, or the like. The amount of water contained in the dried toner base particles is preferably 5% by mass or less, more preferably 2% by mass or less.

  Further, when the dried core-shell type toner base particles are aggregated due to weak interparticle attractive force, a crushing treatment may be performed. As the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

(Addition of external additives)
If necessary, an external additive may be added to the core-shell type toner base particles according to the present invention. The external additive can be prepared by adding and mixing the surface of the dried core-shell type toner base particles as necessary. By adding the external additive, the fluidity and chargeability of the toner are improved, and the cleaning property is improved.

<Developer>
The toner produced by the method for producing a toner of the present invention can be used as a one-component magnetic toner containing a magnetic material, for example, when mixed with a so-called carrier and used as a two-component developer, and a non-magnetic toner alone. It can be used in any case, and any of them can be suitably used.

As the carrier constituting the two-component developer, magnetic particles made of conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. It is preferable to use ferrite particles.
The carrier preferably has a volume average particle diameter in the range of 15 to 100 μm, more preferably in the range of 25 to 60 μm.

  As the carrier, it is preferable to use a carrier coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, cyclohexyl methacrylate-methyl methacrylate copolymer, styrene resin, styrene-acrylic resin, silicone resin, ester resin, fluorine resin, or the like is used. Moreover, it does not specifically limit as resin for comprising a resin dispersion type | mold carrier, A well-known thing can be used, For example, an acrylic resin, a styrene-acrylic resin, a polyester resin, a fluororesin, a phenol resin etc. are used. be able to.

<Fixing method>
As a suitable fixing method using the toner of the present invention, a so-called contact heating method can be mentioned. Examples of the contact heating method include a heat pressure fixing method, a heat roll fixing method, and a pressure contact heating fixing method in which fixing is performed by a rotating pressure member including a fixedly arranged heating body.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said aspect, A various change can be added.

The embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

<Preparation of styrene-acrylic resin particle dispersion (StAc resin)>
(1) First-stage polymerization Into a 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling pipe and nitrogen introduction device, 8 parts by mass of sodium dodecyl sulfate and 3000 parts by mass of ion-exchanged water were charged and stirred at 230 rpm under a nitrogen stream. The internal temperature was raised to 80 ° C. while stirring at a speed. After raising the temperature, 10 parts by mass of potassium persulfate (polymerization initiator) dissolved in 200 parts by mass of ion-exchanged water is added, the temperature is again set to 80 ° C., and a monomer mixture having the following composition is added over 1 hour. After the dropping, polymerization was carried out by heating and stirring at 80 ° C. for 2 hours to prepare a resin fine particle dispersion (x1).
Styrene 480 parts by mass n-butyl acrylate 250 parts by mass Methacrylic acid 68 parts by mass

(2) Second-stage polymerization In a 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling pipe and nitrogen introducing device, 7 parts by mass of polyoxyethylene (2) sodium dodecyl ether sulfate was dissolved in 3000 parts by mass of ion-exchanged water. The prepared solution was charged and heated to 98 ° C., and then 260 parts by mass of a resin fine particle dispersion (x1) and a solution in which a monomer and a release agent having the following composition were dissolved at 90 ° C. were added, and the circulation route A dispersion liquid containing emulsified particles (oil droplets) was prepared by mixing and dispersing for 1 hour using a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.).
Styrene 284 parts by weight n-butyl acrylate (92 parts by weight methacrylic acid 13 parts by weight n-octyl-3-mercaptopropionate 3.0 parts by weight Release agent: behenate behenate (melting point 73 ° C.) 190 parts by weight

  Next, a polymerization initiator solution prepared by dissolving 6 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water is added to the dispersion containing the emulsified particles (oil droplets), and the system is kept at 84 ° C. for 1 hour. Polymerization was carried out by heating and stirring to prepare a dispersion (x2) of resin fine particles.

(3) Third-stage polymerization Further, 400 parts by mass of ion-exchanged water was added to the resin fine particle dispersion (x2) and mixed well, and then 11 parts by mass of potassium persulfate was dissolved in 400 parts by mass of ion-exchanged water. The solution was added, and a monomer mixed solution having the following composition was added dropwise over one hour under a temperature condition of 82 ° C. After completion of the dropwise addition, polymerization was carried out by heating and stirring for 2 hours, followed by cooling to 28 ° C. to prepare a styrene-acrylic resin fine particle dispersion (X1) composed of a vinyl resin (styrene-acrylic resin).
Styrene (St) 350 parts by weight n-butyl acrylate (BA) 215 parts by weight Methacrylic acid (AA) 20 parts by weight n-octyl-3-mercaptopropionate 8 parts by weight

When the physical properties of the obtained styrene-acrylic resin fine particle dispersion (X1) were measured, the volume-based median diameter of the styrene-acrylic resin fine particles was 210 nm, the glass transition temperature (T _g ) of the dried solid was 40 ° C., weight The average molecular weight (Mw) was 32000.

<Preparation of colorant dispersion>
90 parts by weight of sodium dodecyl sulfate was dissolved in 1600 parts by weight of ion-exchanged water while stirring, and while stirring this solution, 420 parts by weight of carbon black “Mogal L” (manufactured by Cabot) was gradually added. A “carbon black particle dispersion” in which carbon black particles [Bk] are dispersed was prepared by performing a dispersion treatment using “CLEAMIX” (manufactured by M Technique Co., Ltd.). When the particle size of the carbon black particles [Bk] in this dispersion was measured using a Microtrac particle size distribution analyzer “UPA-150” (manufactured by Nikkiso Co., Ltd.), the volume-based median diameter was 115 nm.

<Synthesis of Crystalline Polyester Resin (c1)>
1,14-Tetradecanedicarboxylic acid, 306 parts by mass, and 283 parts by mass of 1,6-hexanediol were placed in a reaction vessel equipped with a stirrer, thermometer, cooling pipe, and nitrogen gas introduction pipe. After replacing the inside of the reaction vessel with dry nitrogen gas, 0.1 part by mass of Ti (OBu) ₄ was added as an esterification catalyst, and a stirring reaction was performed at about 180 ° C. for 8 hours in a nitrogen gas stream. Further, 0.2 parts by mass of Ti (OBu) ₄ was added, the temperature was raised to about 220 ° C., and the stirring reaction was performed for 6 hours. A crystalline polyester resin (c1) was obtained. The number average molecular weight (Mn) of the crystalline polyester resin (c1) was 5500, the volume average molecular weight (Mw) was 18000, and the melting point (Tc) was 74 ° C.

<Preparation of crystalline polyester resin fine particle dispersion (C1)>
30 parts by mass of the crystalline polyester resin (c1) was melted and transferred to the emulsification disperser “Cabitron CD1010” (manufactured by Eurotech Co., Ltd.) at a transfer rate of 100 parts by mass per minute. Simultaneously with the transfer of the crystalline polyester resin (c1) in the molten state, 70 mass parts of reagent ammonia water is ion-exchanged in the aqueous solvent tank with respect to the emulsifying and dispersing machine “Cabitron CD1010” (manufactured by Eurotech Co., Ltd.). Diluted aqueous ammonia diluted with water and having a concentration of 0.37% by mass was transferred at a transfer rate of 0.1 liter per minute while being heated to 100 ° C. with a heat exchanger. And this emulsification disperser “Cavitron CD1010” (manufactured by Eurotech Co., Ltd.) is operated under the conditions of a rotor rotational speed of 60 Hz and a pressure of 5 kg / cm ² , thereby producing a crystalline polyester having a solid content of 30 parts by mass. A crystalline polyester resin fine particle dispersion (C1) of resin (c1) was prepared. At this time, the volume-based median diameter of the particles contained in the crystalline polyester resin fine particle dispersion (C1) was 200 nm.

<Synthesis of Crystalline Polyester Resin (c2)>
281 parts by mass of 1,14-tetradecanedicarboxylic acid and 259 parts by mass of 1,6-hexanediol were placed in a reaction vessel equipped with a stirrer, a thermometer, a cooling pipe, and a nitrogen gas introduction pipe. After replacing the inside of the reaction vessel with dry nitrogen gas, 0.1 part by mass of Ti (OBu) ₄ was added as an esterification catalyst, dissolved at about 180 ° C. under a nitrogen gas stream, and then stirred for about 8 hours. .
Separately from the above, raw material monomers of the following addition polymerization resin (styrene-acrylic resin: StAc) unit containing both reactive monomers and a radical polymerization initiator were placed in a dropping funnel.
Styrene 34 parts by mass n-butyl acrylate 12 parts by mass Acrylic acid 2 parts by mass Polymerization initiator (di-t-butyl peroxide) 7 parts by mass Next, the raw material monomer of the addition polymerization resin (StAc) is stirred for 90 minutes with stirring. Then, after aging for 60 minutes, the unreacted addition polymerization monomer was removed under reduced pressure (8 kPa). The amount of monomer removed at this time was very small with respect to the raw material monomer ratio of the resin. Thereafter, 0.8 part by mass of Ti (OBu) ₄ was added as an esterification catalyst, the temperature was raised to 235 ° C., and the reaction was performed at normal pressure (101.3 kPa) for 5 hours and further under reduced pressure (8 kPa) for 1 hour. went.
Next, after cooling to 200 ° C., the mixture was reacted for 1 hour under reduced pressure (20 kPa) to obtain a crystalline polyester resin (c2) which is a hybrid crystalline polyester resin. The crystalline polyester resin (c2) contained 10% by mass of a resin (StAc) unit other than CPEs based on the total amount of the crystalline polyester resin (c2), and was a resin in a form in which CPEs were grafted to StAc. The crystalline polyester resin (c2) had a number average molecular weight (Mn) of 4500 and a melting point (Tc) of 72 ° C.

<Preparation of crystalline polyester resin fine particle dispersion (C2)>
A crystalline polyester resin fine particle dispersion (C2) was prepared in the same manner as in the preparation of the crystalline polyester resin fine particle dispersion (C1) except that the crystalline polyester resin (c1) was changed to the crystalline polyester resin (c2). . At this time, the volume-based median diameter of the particles contained in the crystalline polyester resin fine particle dispersion (C2) was 230 nm.

<Synthesis of Amorphous Polyester Resin s1>
The raw material monomer and radical polymerization initiator of the following addition polymerization resin (styrene-acrylic resin: StAc) unit containing both reactive monomers were placed in a dropping funnel.
Styrene 80 parts by mass n-butyl acrylate 20 parts by mass Acrylic acid 10 parts by mass Polymerization initiator (di-t-butyl peroxide) 16 parts by mass

In addition, the raw material monomer of the following polycondensation resin (amorphous polyester resin) unit is put into a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170 ° C. to dissolve. It was.
Bisphenol A propylene oxide 2 mol adduct 255.5 parts by mass Bisphenol A ethylene oxide 2 mol adduct 30.2 parts by mass Terephthalic acid 56.3 parts by mass Fumaric acid 35.0 parts by mass Adipic acid 22.0 parts by mass

Next, the raw material monomer of the addition polymerization resin was dropped over 90 minutes with stirring, and after aging for 60 minutes, the unreacted addition polymerization monomer was removed under reduced pressure (8 kPa).
Thereafter, 0.4 parts by mass of Ti (OBu) ₄ was added as an esterification catalyst, the temperature was raised to 235 ° C., and the reaction was performed at normal pressure (101.3 kPa) for 5 hours and further under reduced pressure (8 kPa) for 1 hour. went.

Next, after cooling to 200 ° C., the reaction was performed under reduced pressure (20 kPa) until the desired softening point was reached. Next, the solvent was removed to obtain an amorphous polyester resin s1 (hereinafter also referred to as “shell resin (s1)”) as an amorphous polyester resin. With respect to the obtained resin for shell (s1), the glass transition temperature (T _ga ) was 60 ° C., and the weight average molecular weight (Mw) was 27000. The softening point at this time was 109 ° C.

<Preparation of Amorphous Polyester Resin Particle Dispersion (S1)>
100 parts by mass of the obtained shell resin (s1) is dissolved in 400 parts by mass of ethyl acetate (manufactured by Kanto Chemical Co., Inc.) and mixed with 638 parts by mass of a 0.26% by mass sodium lauryl sulfate solution prepared in advance. While stirring, ultrasonically disperse with an ultrasonic homogenizer “US-150T” (manufactured by Nippon Seiki Seisakusho) at V-LEVEL 300 μA for 30 minutes, and then heated to 40 ° C., the diaphragm vacuum pump “V-700” ( Using BUCHI), ethyl acetate was completely removed while stirring under reduced pressure for 3 hours to prepare an amorphous polyester resin particle dispersion (S1) for shell having a solid content of 13.5% by mass. did. At this time, the particles contained in the dispersion (S1) had a volume average particle size of 140 nm.

<Synthesis of Amorphous Polyester Resin s2>
In the synthesis of the shell resin (s1), the non-crystalline polyester resin s2 (hereinafter referred to as “shell resin (s2)”) was similarly used except that the reaction was stopped when the softening point reached 105.6 ° C. Synthesis). The obtained shell resin (s2) had a glass transition temperature of 58 ° C. and a weight average molecular weight (Mw) of 16000.

<Preparation of Amorphous Polyester Resin Particle Dispersion (S2)>
The amorphous polyester resin particle dispersion (S1) was prepared by the same method except that the shell resin (s1) was changed to the shell resin (s2). The particles contained in the amorphous polyester resin particle dispersion (S2) had a volume average particle shape of 162 nm.

<Manufacture of toner base particles 1>
In a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling pipe, 200 parts by mass of a styrene-acrylic resin fine particle dispersion (X1) in terms of solid content, 20 parts by mass of a colorant dispersion in terms of colorant solids, and 2000 parts by mass of ion-exchanged water was added, and then a 5 mol / liter aqueous sodium hydroxide solution was further added to the reaction vessel to adjust the pH of the mixed solution in the reaction vessel to 10. Next, an aqueous solution obtained by dissolving 60 parts by mass of magnesium chloride in 60 parts by mass of ion-exchanged water as a flocculant was added to the above mixed solution over 10 minutes at 25 ° C. with stirring (Step I).

  Next, the obtained mixed liquid was heated to 78 ° C. over 90 minutes, and then 20 parts by mass of the crystalline polyester resin fine particle dispersion (C1) in terms of solid content was added to the mixed liquid over 20 minutes. Then, the number of stirring is adjusted as appropriate, the particle size of the associated particles is measured with “Coulter Multisizer 3” (manufactured by Beckman Coulter), and the volume-based median diameter of the associated particles is reduced to 5.5 μm. Aggregation and coalescence were performed to obtain a core particle dispersion (step II).

  The obtained core particle dispersion was cooled to 45 ° C. (Step III).

A 5 mol / liter sodium hydroxide aqueous solution was added to the cooled core particle dispersion, and the pH was adjusted to pH 8 (pH _A ) at a converted value at 25 ° C. Thereafter, the core particle dispersion was heated to 63 ° C. (“shell adhesion temperature T ₁ ” described in Table 1). The amorphous polyester resin particle dispersion (S1) adjusted to pH 2 ((pH _B , converted value at 25 ° C.)) was added to the heated core particle dispersion over 20 minutes. The particles were aggregated, and an aqueous solution in which 190 parts by mass of sodium chloride was dissolved in 760 parts by mass of ion-exchanged water was added (Step IV).

Subsequently, the obtained dispersion was heated and stirred at 72 ° C. (“fusion temperature T ₂ ” described in Table 1) to advance particle fusion (step V).

When the average circularity of the particles in the dispersion was measured using a measuring device “FPIA-3000” (manufactured by Sysmex) (with 4000 HPF detections), the average circularity reached 0.958. The dispersion was cooled to 35 ° C. to stop the fusion of the particles. Thus, a toner dispersion liquid 1 containing toner base particles 1 was obtained.
The toner base particles 1 were separated from the obtained toner dispersion 1, washed, and then dried to a water content of less than 1% to obtain toner base particles 1 (Step VI).

<Production of toner base particles 2 to 19>
From the production of the toner base particles 1, the temperature in Step III to Step V, the pH of the core particle dispersion at 25 ° C. (pH _A ), and the pH of the dispersion of amorphous polyester resin particles at 25 ° C. (pH _B ). And toner base particles 2 to 19 were produced.
Table 1 shows the changed conditions. Others were manufactured in the same manner as the toner base particles 1.

[Manufacture of toner 1 for developing electrostatic image]
100 parts by mass of the obtained toner base particles 1, 0.6 parts by mass of hydrophobic silica (number average primary particle size = 12 nm, degree of hydrophobicity = 68) and hydrophobic titanium oxide (number average primary particle size = 20 nm, hydrophobic) Degree of conversion = 63) 1.0 part by mass was added and mixed with a “Henschel mixer” (manufactured by Nihon Coke Kogyo Co., Ltd.) at a rotating blade peripheral speed of 35 mm / sec at 32 ° C. for 20 minutes. The toner 1 for developing an electrostatic charge image was produced by applying an external additive treatment to remove coarse particles.

[Production of Toner 2-19 for Developing Electrostatic Image]
In the production of the toner 1 for developing an electrostatic charge image, it was produced in the same manner as the toner 1 for developing an electrostatic charge image except that the toner base particles 1 were changed to toner base particles 2 to 19.

[Evaluation method]
For electrostatic image developing toners 1 to 19, developers 1 to 19 were produced as follows.
The developers 1 to 19 are loaded into a developing device of a commercially available color multifunction peripheral “bizhub PRO C1060” (manufactured by Konica Minolta Co., Ltd.) to form a test image. did. The results are shown in Table 2. In the following evaluations, ◎, ○, and Δ are all passed as evaluation criteria.

<Manufacture of developer>
(1) Production of Carrier 100 parts by mass of ferrite core material particles and 5 parts by mass of copolymer resin fine particles of cyclohexyl methacrylate / methyl methacrylate (copolymerization ratio 5/5) are put into a high-speed mixer equipped with stirring blades, and 120 A carrier with a volume-based median diameter of 35 μm was obtained by stirring and mixing at 30 ° C. for 30 minutes to form a resin coating layer on the surface of the ferrite core material particles by the action of mechanical impact force.
The volume-based median diameter of the carrier was measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by Sympathec) equipped with a wet disperser.

(2) Mixing of toner and carrier The carrier is added to each of the electrostatic image developing toners 1 to 19 so that the toner concentration becomes 6.5% by mass, and a micro V-type mixer (Tsukai) is added. Developers 1 to 19 were prepared by mixing for 30 minutes at a rotation speed of 45 rpm using RIKEN CHEMICAL CO., LTD. And used for evaluation of toners 1 to 19 for developing electrostatic images.

<Low-temperature fixability (under offset property)>
Under offset refers to an image defect that peels off a transfer material such as recording paper because the toner layer is not sufficiently melted by heat applied when passing through the fixing machine.
The image evaluation was performed by sequentially loading the toner prepared above and a developer into the above-described developing device. In addition, modification was made so that the fixing temperature, the toner adhesion amount, and the system speed could be set freely. Using NPI 128 g / m ² (manufactured by Nippon Paper Industries) as the evaluation paper, a solid image with a toner adhesion amount of 11.3 g / m ² was fixed at a fixing speed of 300 mm / sec, the temperature of the fixing upper belt was 100 to 200 ° C., and the fixing lower roller When the temperature was set at 100 ° C. and fixing was performed at a level of 5 ° C., the lower limit fixing temperature of the fixing upper belt where no under-offset occurred was evaluated and used as an index for low temperature fixing properties. The lower this fixing minimum temperature is, the better the fixing property is, and a temperature lower than 145 ° C. is considered acceptable.
: Fixing lower limit temperature is less than 120 ° C. ○: Fixing lower limit temperature is from 120 ° C. to less than 135 ° C. Δ: Fixing lower limit temperature is from 135 ° C. to less than 145 ° C. ×: Fixing lower limit temperature is 145 ° C. or more.

<Heat resistant storage>
0.5 g of toner is placed in a 10 mL glass bottle with an inner diameter of 21 mm, the lid is closed, shaken 600 times at room temperature with a tap denser KYT-2000 (manufactured by Seishin Enterprise), and then removed at 57.5 ° C., 35 It was left for 2 hours in an environment of% RH. Next, place the toner on a 48-mesh (mesh 350 μm) sieve, taking care not to crush the toner aggregates, set the powder tester (manufactured by Hosokawa Micron), and fix it with a press bar and knob nut. Then, after adjusting the vibration strength to a feed width of 1 mm and applying vibration for 10 seconds, the ratio (mass%) of the amount of toner remaining on the sieve was measured as the toner aggregation rate.
The toner aggregation rate is a value calculated by the following formula.
Toner aggregation rate (mass%) = residual toner mass on sieve (g) /0.5 (g) × 100
The toner aggregation rate of the toner was evaluated according to the criteria described below and used as an index of heat resistant storage stability.
A: The toner aggregation rate is less than 10% by mass (the heat-resistant storage stability of the toner is extremely good).
○: The toner aggregation rate is 10% by mass or more and less than 15% by mass (good heat-resistant storage property of the toner)
Δ: The toner aggregation rate is 15% by mass or more and less than 20% by mass (the heat-resistant storage property of the toner is slightly inferior but is an acceptable level).
X: The toner aggregation rate is 20% by mass or more (the toner has poor heat storage stability and cannot be used).

<Document offset resistance>
The fixing conditions were changed so that the gloss of 60 to 70 was applied to a solid patch with an adhesion amount of 10.0 g / m ² on POD128 (Oji Paper) using the machine described above, and a fixed image was output. The gloss was measured with a microgloss 75 ° manufactured by Gardner. In addition, a sheet of white POD128 paper that was passed under the identification condition was prepared, and temperature and pressure were applied to the image portion and the image portion, and the image portion and the non-image portion bonded together. The temperature and pressure conditions are two levels of 10 g / m ² at 60 ° C. and 80 g / m ² at 50 ° C. After the samples were exposed for 1 week, they were slowly peeled off, and the degree of migration to one side was visually evaluated for document offset resistance (described as “DO” in Table 2) at the following rank.
◎: Level where there is no transition to one side and no problem ○: There is no transition to one side of the image and there is uneven glossiness △: There is a slight transition to one side of the image, but acceptable level ×: Difficult to separate, There is a lot of transition to one side

<Transferability>
Under a high temperature and high humidity environment (temperature 30 ° C, humidity 80% RH), a solid image of 10cm square was printed as a test image, and the toner mass developed and adhered on the photoconductor (before W transfer) and on the transfer paper The mass of the toner transferred and adhered to the toner (after W transfer) was measured, and the transfer rate defined by the following formula (A) was calculated. The results are shown in Table 2. In addition, the case where a transfer rate is 85% or more is set as a pass.
Formula (A): Transfer rate (%) = (after W transfer / before W transfer) × 100
○: 90% or more △: 85% or more and less than 90% ×: less than 85%

<GI value>
For developers 1 to 19, in a full-color copier “bizhub PRO C1060” (manufactured by Konica Minolta Co., Ltd.) as a commercially available composite printer, the surface temperature of the fixing heat roller can be changed within the range of 100 to 200 ° C. In a state where the surface temperature of the fixing heat roller is set to the higher one of the low temperature offset temperature and the lower limit fixing temperature (minimum fixing temperature), a thickness of 250 g / A solid image (100% image) having a toner adhesion amount of 10 mg / cm ² and a 50% flat screen image are formed on an m ² art-coated paper, and the GI value of the 50% flat screen image portion is determined by an image analysis system “ It measured using "GI-es-8500AAC" (made by NATALAL INSTRUMENT). If the GI value is less than 0.22, it is judged that the image quality is durable and can be used practically with little roughness.
○: Less than 0.20 Δ: 0.20 or more and less than 0.22 ×: 0.22 or more

  As shown in Table 2, according to the method for producing a toner for developing an electrostatic charge image of the present invention, the toner for developing an electrostatic charge image having improved heat storage stability, fluidity, low-temperature fixability, document offset resistance and image quality. It can be seen that can be manufactured.

Claims (5)

A method for producing a toner for developing an electrostatic image containing core / shell toner base particles containing at least a binder resin and a release agent,
The binder resin includes at least a styrene-acrylic resin, a crystalline polyester resin, and an amorphous polyester resin, and
A method for producing a toner for developing an electrostatic charge image, comprising at least the following steps I to V.
(Step I): Step of adding a flocculant under stirring to a dispersion liquid mixture containing at least the styrene-acrylic resin and the mold release agent (Step II): the flocculant added in Step I The dispersion of the crystalline polyester resin is added to the dispersion mixture, and at least the styrene-acrylic resin, the release agent, and the crystalline polyester resin are aggregated and united under heating and stirring to disperse the core particles. Step of obtaining a liquid (Step III): Step of cooling the core particle dispersion obtained in Step II to a temperature of at least the crystallization peak temperature (T _qc ) of the crystalline polyester resin of −15 ° C. (Step IV): the temperature of the dispersion of the core particles cooled in the step III,
(1) At least the temperature below the melting point (T _mc ) of the crystalline polyester resin,
(2) The glass transition temperature (T _gs ) of the styrene-acrylic resin + 5 ° C. or higher.
(3) the amorphous polyester glass transition temperature of the resin _(T ga) + 3 ° C. and below temperatures and ₍₄₎ the _{T gs} <temperature satisfies the relationship T ga _{<T qc,}
The amorphous polyester resin particle dispersion is added to the core particle dispersion, and the amorphous polyester resin particles are adhered to the surface of the core particles as shell particles. Step of obtaining (Step V): The core-shell particle dispersion is brought to a temperature not lower than the glass transition temperature (T _ga ) of the amorphous polyester resin + 3 ° C. and not higher than the melting point (T _mc ) of the crystalline polyester resin. Adjusting, fusing the core particles, the shell particles, and the shell particles together to obtain a core-shell type toner base particle dispersion liquid In the step IV, the pH of the core particle dispersion at 25 ° C. (pH _A ) and the pH of the amorphous polyester resin particle dispersion at 25 ° C. before addition to the core particle dispersion (pH _B) 2) satisfy the following formulas (a) to (c): The method for producing a toner for developing an electrostatic charge image according to claim 1.
Formula (a) 3 ≦ pH _A −pH _B
Formula (b) 7 ≦ pH _A ≦ 10
Formula (c) 2 ≦ pH _B ≦ 5   The volume average particle diameter of the amorphous polyester resin particles in the dispersion of the amorphous polyester resin particles added in the step IV is in the range of 50 to 300 nm. A method for producing a toner for developing an electrostatic image according to claim 1. The glass transition temperature (T _gs ) of the styrene-acrylic resin is in the range of 35-50 ° C.,
The amorphous polyester resin has a glass transition temperature (T _ga ) in the range of 53 to 63 ° C .;
4. The electrostatic charge image developing toner according to claim 1, wherein the crystalline polyester resin has a melting point (T _mc ) in a range of 65 to 80 ° C. 5. Production method.   The electrostatic image development according to any one of claims 1 to 4, wherein the amorphous polyester resin is an amorphous polyester resin chemically bonded to a styrene-acrylic resin. Of manufacturing toner.