JP6060713B2 - Method for producing toner for developing electrostatic image - Google Patents

Description

The present invention relates to a method for producing a toner for developing electrostatic images you containing toner base particles having a core-shell structure, and more particularly, the toner base particles, styrene - resin core containing an acrylic resin, a polyester resin relates to a method for producing Ah Ru toner for developing electrostatic images with particles of structure coated with a shell resin containing a.

In recent years, there has been an increasing need for high-speed, high-quality, and energy-saving electrophotographic image forming apparatuses. Accordingly, toner for developing electrostatic images (hereinafter also simply referred to as “toner”) has heat resistance. Further improvement in crush resistance, durability and low temperature fixability is required.
Therefore, for the purpose of stabilizing the chargeability of the toner surface that directly affects the durability and high image quality, a technology relating to a toner containing a metal complex composed of a salicylic acid derivative and a metal in a polyester resin has been disclosed. (For example, refer to Patent Documents 1 to 3.)
However, in the case of the toners described in Patent Documents 1 to 3, since the metal complex composed of the salicylic acid derivative and the metal is not in the surface layer of the toner but enters the inside, sufficient chargeability, heat resistance, and crush resistance are obtained. It has been clarified by the inventor of the present application that there is a problem that it cannot be obtained.

JP 2002-351137 A JP 2010-181845 A JP 2010-026404 A

The present invention has been made in view of the above problems or situation, the problem to be solved is, heat resistance, a method for manufacturing a can Ru toner for electrostatic image development to improve the crush resistance and charge stability Is to provide.

In order to solve the above problems, the present inventor is a method for producing a toner for developing an electrostatic image containing toner base particles having a core / shell structure in the course of examining the cause of the above problems, Inclusion of a salicylic acid metal complex composed of a salicylic acid derivative and a divalent metal in the resin portion for the shell of the particle can improve the charging stability, and free metal ions released from the salicylic acid metal complex However, the present inventors have found that metal crosslinking occurs with the carboxylic acid of the shell resin, the crosslinking of the shell layer proceeds, and heat resistance, crush resistance and charging stability are improved.
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 toner base particles having a core-shell structure,
The toner base particles are particles having a structure in which a core resin containing a styrene-acrylic resin is coated with a shell resin containing a polyester resin graft-modified with a styrene-acrylic resin, and at least the shell resin Containing a salicylic acid metal complex consisting of a salicylic acid derivative and a divalent metal in the part,
A method for producing an electrostatic charge image developing toner, comprising at least the following steps (1) to (3):
(1) A step of preparing a core resin particle dispersion in which core resin particles containing the styrene-acrylic resin are dispersed in an aqueous medium.
(2) A step of preparing a shell resin particle dispersion in which the shell resin particles containing the polyester resin and the salicylic acid metal complex are dispersed in an aqueous medium.
(3) A step of forming the shell layer on the surface of the core resin particles by adding the shell resin particle dispersion to the core resin particle dispersion
2. The step (2) of preparing the resin particle dispersion for a shell comprises containing the salicylic acid metal complex in the polyester resin in a state of emulsified fine particles using a phase inversion emulsification method. A method for producing a toner for developing an electrostatic charge image according to item 2.

〔一般式（１）中、Ｍは、マグネシウム、亜鉛、ジルコニウム、銅、鉄、カルシウム、ニッケル又はコバルトのいずれかを表す。Ｒ^１、Ｒ^２及びＲ^３は、それぞれ独立して、水素原子、直鎖又は分岐鎖状の炭素数１〜１０のアルキル基を表す。ｍは２を表し、ｎは１を表す。〕 3 . 3. The method for producing a toner for developing an electrostatic charge image according to item 1 or 2 , wherein the salicylic acid metal complex has a structure represented by the following general formula (1).

[In General Formula (1), M represents any of magnesium, zinc, zirconium, copper, iron, calcium, nickel, or cobalt. R ¹ , R ² and R ³ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms. m represents 2 and n represents 1. ]

4 . A solution in which the toner base particles are dissolved in methyl ethyl ketone is referred to as solution (1), and a solution in which methanol is dissolved in methanol is referred to as solution (2).
When the respective solutions (1) and (2) were measured under the same conditions by high performance liquid chromatography, the peak area of the peak (P ₂ ) derived from the salicylic acid derivative obtained in the solution (2) was expressed as S _2. with a peak area of a peak (P ₁₎ derived from a salicylic acid derivative having the same retention time as P ₂ solution (1) When S _1, the first term and satisfies the following formula (a) The method for producing a toner for developing an electrostatic charge image according to any one of Items 3 to 3 .
Formula (A): 0.8 <S ₂ / S ₁ ≦ 1

5 . The salicylic acid metal complex, the styrene - acrylic resin and the styrene - based on the total resin graft-modified polyester resin with an acrylic resin, characterized by Rukoto is contained in the range of 0.1 to 10 mass% The method for producing a toner for developing an electrostatic charge image according to any one of items 1 to 4 .

6 . As the external additive, the average particle diameter from the first term, wherein Rukoto silica is contained in the range of 70~150nm the toner according to any one of up to fifth term production Way .

By the above means of the present invention, it is possible to provide a method for producing a toner for developing an electrostatic image capable of improving heat resistance, crush resistance and charging stability.
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
A metal complex composed of a salicylic acid derivative and a metal is generally used as a charge control agent that stabilizes the charge amount of the toner. In such a metal complex, a compatible resin depending on the metal used. May be different. Therefore, it is considered that the charge amount can be stabilized by using a metal complex composed of a salicylic acid derivative that is compatible only with the shell resin and a metal in the core-shell structure of the toner.
Therefore, in the present invention, the toner base particles are particles having a structure in which a core resin containing a styrene-acrylic resin is coated with a shell resin containing a polyester resin, and at least the shell resin portion has a salicylic acid derivative. By adding a salicylic acid metal complex composed of a divalent metal, the divalent metal is compatible with the polyester resin (ethyl acetate) contained in the shell resin and dissolved in the styrene contained in the core resin. It becomes difficult to do. As a result, it is estimated that the charge amount is stabilized.
In addition, free metal ions released from the salicylic acid metal complex cause metal cross-linking with the carboxylic acid of the polyester resin contained in the shell resin, which is a constituent material of the toner. It is estimated that the heat resistance and crush resistance are improved.

The electrostatic image developing toner according to the present invention is an electrostatic image developing toner containing toner base particles having a core / shell structure, wherein the toner base particles contain a styrene-acrylic resin. And a salicylic acid metal complex comprising a salicylic acid derivative and a divalent metal at least in the shell resin part .

As an embodiment of the present invention, the salicylic acid metal complex preferably has a structure represented by the above general formula (1) from the viewpoint of manifesting the effects of the present invention.
In addition, a solution in which the toner base particles are dissolved in methyl ethyl ketone is referred to as solution (1), a solution in which methanol is dissolved in methanol is referred to as solution (2), and the respective solutions (1) and (2) are the same by high performance liquid chromatography. When measured under the conditions, the peak area of the peak (P ₂ ) derived from the salicylic acid derivative obtained in the solution (2) is S ₂ and derived from the salicylic acid derivative having the same retention time as P _{2 in the} solution (1) When the peak area of the peak (P ₁ ) to be taken is S ₁ , it is preferable to satisfy the following formula (A).
Formula (A): 0.8 <S ₂ / S ₁ ≦ 1
As a result, the shell layer contains a large amount of the salicylic acid metal complex, and the heat resistance, crush resistance, and charging stability can be further improved.

Moreover, it is in the polyester resin which is resin for shells that the said salicylic acid metal complex is contained within the range of 0.1-10 mass% with respect to all the resins of the said styrene-acrylic resin and the said polyester resin. It is preferable in terms of being compatible with each other and improving heat resistance, crush resistance, and charging stability.
Moreover, it is preferable from the viewpoint of durability, cleaning properties, and transferability that silica having an average particle diameter of 70 to 150 nm is contained as an external additive.

The method for producing the toner for developing an electrostatic charge image of the present invention is a method for producing a toner for developing an electrostatic charge image containing toner base particles having a core / shell structure, wherein the toner base particles are made of styrene-acrylic resin. Particles having a structure in which a core resin containing a polyester resin is coated with a shell resin, and at least the shell resin portion contains a salicylic acid metal complex composed of a salicylic acid derivative and a divalent metal. In view of uniform toner particle size, it is preferable to have at least the following steps (1) to (3).
(1) Step of preparing a core resin particle dispersion in which core resin particles containing the styrene-acrylic resin are dispersed in an aqueous medium (2) Shell containing the polyester resin in an aqueous medium Step (3) of preparing a resin particle dispersion for shell in which resin particles for metal and the metal salicylate complex are dispersed (3) Adding the resin particle dispersion for shell to the core resin particle dispersion, Forming a shell layer on the surface of resin particles

  The step (2) of preparing the resin particle dispersion for a shell includes adding the salicylic acid metal complex to the polyester resin in a state of emulsified fine particles using a phase inversion emulsification method. It is preferable in that emulsified particles can be obtained.

  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 toner for developing electrostatic image ]
An electrostatic charge image developing toner of the present invention is a toner for developing an electrostatic charge image containing toner base particles having a core / shell structure, wherein the toner base particles include a core resin containing a styrene-acrylic resin. Further, the particles are structured to be coated with a shell resin containing a polyester resin, and at least the shell resin portion contains a metal complex composed of a salicylic acid derivative and a divalent metal.
The metal complex according to the present invention includes a metal complex salt.
Hereinafter, the components of the toner of the present invention will be described in detail.

[Styrene-acrylic resin]
Among the polymerizable monomers constituting the styrene-acrylic resin used in the present invention, examples of the styrene monomer include styrene, methylstyrene, methoxystyrene, ethylstyrene, propylstyrene, butylstyrene, phenylstyrene, and chlorostyrene. And styrene monomers such as
Examples of the acrylic monomer include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, dodecyl acrylate, stearyl acrylate, ethyl hexyl acrylate, lauryl acrylate, methyl methacrylate, Acrylic acid ester monomers such as ethyl methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, dodecyl methacrylate, stearyl methacrylate, ethylhexyl methacrylate, lauryl methacrylate, and the like, and methacrylic acid ester monomers.
Among these, it is preferable to use an acrylic acid monomer having a carboxylic acid as a functional group.

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 acetate, acrylamide, methacrylamide, acrylonitrile, ethylene, propylene, butylene vinyl chloride, N-vinyl pyrrolidone, and butadiene. It is done.
The copolymerization ratio of these polymerizable monomers is selected so that the glass transition temperature of the resin constituting the obtained core particle is within the range of 30 to 60 ° C, preferably within the range of 30 to 50 ° C. Is good.
The softening point is in the range of 80 to 110 ° C, preferably in the range of 90 to 100 ° C.
A polyfunctional vinyl monomer may be further used as the polymerizable monomer. Examples of the polyfunctional vinyl monomer include diacrylates such as ethylene glycol, propylene glycol, butylene glycol and hexylene glycol, dimethacrylates of tri- or higher alcohols such as divinylbenzene, pentaerythritol, and trimethylolpropane, and trimethylolpropane. And methacrylate.
The copolymerization ratio of the polyfunctional vinyl monomer to the entire polymerizable monomer is usually 0.001 to 5% by mass, preferably 0.003 to 2% by mass, more preferably It exists in the range of 0.01-1 mass%.
Although the gel component insoluble in tetrahydrofuran is generated by using the polyfunctional vinyl monomer, the proportion of the gel component in the whole polymer is usually 40% by mass or less, preferably 20% by mass or less.

In the present invention, a chain transfer agent may be added together with the polymerizable monomer. The molecular weight of the polymer can be controlled by adding a chain transfer agent.
Known chain transfer agents can be used, and examples thereof include alkyl mercaptans and mercapto fatty acid esters.
The addition amount of the chain transfer agent varies depending on the desired molecular weight and molecular weight distribution, but specifically, it is preferably added within a range of 0.1 to 5% by mass with respect to the polymerizable monomer.
The polymerization initiator used for the polymerization is not particularly limited, and known ones can be used.

[Polyester resin]
<Carboxylic acid monomer>
The polyester resin used in the present invention may contain other polyvalent carboxylic acid as a constituent component as an acid monomer. These polyvalent carboxylic acids are compounds containing two or more carboxy groups in one molecule.
Among these, a divalent carboxylic acid is a compound containing two carboxy groups in one molecule. For example, oxalic acid, succinic acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid , Nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydro Terephthalic acid, malonic acid, pimelic acid, tartaric acid, mucous acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-pheny Range glycolic acid, p-phenylene diglycolic acid, o-phenylene jig Cholic acid, diphenylacetic acid, diphenyl-p, p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, dodecenyl succinic acid, etc. Can be mentioned.
Examples of the polyvalent carboxylic acid other than the divalent carboxylic acid include trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, and pyrenetetracarboxylic acid.
Examples of polyvalent carboxylic acid derivatives include alkyl esters, acid anhydrides and acid chlorides of polyvalent carboxylic acids, and examples of polyhydric alcohol derivatives include ester compounds of polyhydric alcohols and hydroxycarboxylic acids. it can.

<Alcohol monomer>
The polyhydric alcohol is a compound containing two or more hydroxy groups in one molecule. Among these, a divalent polyol (diol) is a compound containing two hydroxy groups in one molecule. For example, ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decane. Examples include diol, dodecanediol, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, and the like.
Examples of polyols other than divalent polyols include glycerin, pentaerythritol, hexamethylol melamine, hexaethylol melamine, tetramethylol benzoguanamine, and tetraethylol benzoguanamine.

<Polyester resin polymerization catalyst>
As the catalyst for polymerization of the polyester resin according to the present invention, a general known catalyst can be used, and examples thereof include titanium tetraisopropoxide.
The glass transition point Tg of the polyester resin particles is preferably in the range of 40 to 70 ° C, more preferably in the range of 50 to 65 ° C.
A Tg of 40 ° C. or higher is preferred because the resin itself in the high temperature region has cohesion and does not cause hot offset during fixing. Further, it is preferable that Tg is 70 ° C. or lower because sufficient melting can be achieved and a suitable minimum fixing temperature can be obtained. The softening point is preferably in the range of 80 to 110 ° C.
Moreover, it is preferable that the weight average molecular weight of the polyester resin to be used exists in the range of 1500-60000, More preferably, it exists in the range of 3000-40000.
A weight average molecular weight of 1500 or more is preferable because a cohesive force suitable as a binder resin can be obtained and the hot offset property is good. Further, it is preferable that the weight average molecular weight is 60000 or less because good hot offset property and a suitable minimum fixing temperature can be obtained.
Further, the polyester resin of the present invention may be graft-modified with a styrene-acrylic resin as necessary.

[Salicylic acid metal complex]
The salicylic acid metal complex contained in the toner of the present invention is a metal complex composed of a salicylic acid derivative and a divalent metal, and has a structure represented by the following general formula (1).

In general formula (1), M represents any of magnesium, zinc, zirconium, copper, iron, calcium, nickel or cobalt.
R ¹ , R ² and R ³ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms. Examples of such an alkyl group include tert-butyl, pentyl (C ₅ H ₁₁ ), 2-ethylhexyl, and the like.
m represents 2 and n represents 1.

  The salicylic acid metal complex may be contained in the range of 0.1 to 10% by mass, more preferably in the range of 2 to 5% by mass with respect to 100% by mass of the binder resin (styrene-acrylic resin and polyester resin). preferable.

In the toner of the present invention, a solution in which toner base particles are dissolved in methyl ethyl ketone at 25 ° C. is defined as solution (1), and a solution in which methanol is dissolved in methanol at 25 ° C. is defined as solution (2). ) Measured under the same conditions by high performance liquid chromatography, the peak area of the peak (P ₂ ) derived from the salicylic acid derivative obtained in the solution (2) is the same as S _{2 in} the solution (1) and P _{2 in the} solution (1). When the peak area of the peak (P ₁ ) derived from the salicylic acid derivative having a retention time is S ₁ , it is preferable to satisfy the following formula (A).
Formula (A): 0.8 <S ₂ / S ₁ ≦ 1
That is, the salicylic acid metal complex is preferably contained in a large amount in the shell layer of the toner.

Here, the measurement conditions of HPLC are as follows.
(HPLC measurement conditions)
Column: Inertsil ODS-2 (particle size 5 μm, 4.6 mm ID × 150 mm L) (manufactured by GL Sciences Inc.)
Oven: 40 ° C
Flow rate: 1.0 ml / min Eluent composition: A: 0.1 M ammonium acetate aqueous solution (pH 5) / B: methanol Gradient: 0 minutes (B: 60%) to 20 minutes (B: 100%)
Injection volume: 10μl
Detection: UV310nm
Moreover, the calculation method of the ratio of the salicylic acid metal complex contained in the shell layer is as follows.
In the following procedure, the concentration of each measurement sample solution of the solution (1) in which the toner base particles are dissolved in methyl ethyl ketone and the solution (2) in which methanol is dissolved at 25 ° C. %, And after dissolution, the residue was filtered through a filter to obtain a measurement sample solution.
(Method of calculation)
(A) The retention time is confirmed with a standard (a metal complex composed of a salicylic acid derivative and a metal).
(B) A calibration curve showing the relationship between the amount of the standard and the peak area is created.
(C) The content of the salicylic acid metal complex in the whole toner is calculated from the peak area S ₁ (intensity) in methyl ethyl ketone extraction and the calibration curve.
(D) The content of the salicylic acid metal complex in the shell layer of the toner is calculated from the peak area S ₂ (intensity) in methanol extraction and a calibration curve.
(E) The ratio of the salicylic acid metal complex contained in the shell layer is calculated from the content of the salicylic acid metal complex in the entire toner and the content of the salicylic acid metal complex in the shell layer.

<Dispersion of salicylic acid metal complex in polyester resin>
A phase inversion emulsification method is used for dispersing the gold salicylate complex in the polyester resin.
Specifically, the phase inversion emulsification method comprises dissolving a polyester resin and a salicylic acid metal complex in an organic solvent to form a resin solution, and stirring the resin solution while adding an aqueous medium to the resin solution. In this method, a dispersion in which particles of the resin solution are dispersed in a medium is formed, and an organic solvent is removed to form an emulsion.

[Toner base particles]
The “toner base particles” as used in the present invention means a shell containing a binder resin (shell resin) on the surface of toner core particles containing at least a binder resin (core resin) and a colorant. It is a particle having a core-shell structure having a layer. The toner base particles can be used as toner particles as they are, but it is usually preferable to add the external additives.

<Average circularity of toner base particles>
The average circularity of the toner base particles used in the present invention is preferably in the range of 0.850 to 0.990.
Here, the average circularity of the toner base particles is a value measured using “FPIA-2100” (manufactured by Sysmex).
Specifically, the toner base particles are moistened in a surfactant aqueous solution, and ultrasonic dispersion is performed for 1 minute. After dispersion, the HPF is used in the measurement condition HPF (high magnification imaging) mode using “FPIA-2100”. Measurement is performed at an appropriate concentration within the range of 3000 to 10,000 detections. Within this range, reproducible measurement values can be obtained. The circularity is calculated by the following formula.
Circularity = (perimeter of a circle having the same projection area as the particle image) / (perimeter of the particle projection image)
The average circularity is an arithmetic average value obtained by adding the circularity of each particle and dividing by the total number of particles measured.

<Particle size of toner base particles>
The particle size of the toner base particles used in the present invention is preferably in the range of 3 to 10 μm in terms of volume-based median diameter (D ₅₀ ).
The volume-based median diameter (D ₅₀ ) of the toner base particles can be measured and calculated using, for example, an apparatus in which a computer system for data processing is connected to Multisizer 3 (manufactured by Beckman Coulter).
As the measurement procedure, 0.02 g of toner base particles were added to 20 ml of a surfactant solution (for example, a surfactant solution in which a neutral detergent containing a surfactant component was diluted 10 times with pure water for the purpose of dispersing toner particles. Then, ultrasonic dispersion is performed for 1 minute to prepare a toner particle dispersion. This toner particle dispersion is injected into a beaker containing ISOTON II (manufactured by Beckman Coulter) in a sample stand with a pipette until the measured concentration falls within a range of 5 to 10%, and the measuring machine count is increased to 25,000. Set and measure. The aperture diameter of the multisizer 3 is 100 μm.

[Toner Production Method]
The toner production method in the present invention preferably uses an emulsion aggregation method.
In the emulsion aggregation method, a dispersion of binder resin particles (hereinafter also referred to as “binder resin particles” manufactured by emulsification, for example, core resin particles or shell resin particles) is used as a colorant particle. (Hereinafter, also referred to as “colorant particles”), and agglomerated until a desired toner base particle diameter is obtained. Further, the shape is controlled by fusing the binder resin particles. This is a method for producing toner base particles. Here, the binder resin particles may optionally contain a release agent or other additives.

An example of using the emulsion aggregation method as a method for producing the toner is shown below.
(0) Step of preparing a colorant particle dispersion in which colorant particles are dispersed in an aqueous medium (1) Core in which resin particles for cores containing a styrene-acrylic resin are dispersed in an aqueous medium Step (2) for preparing resin particle dispersion for shell (2) Step for preparing resin particle dispersion for shell in which resin particles for shell containing polyester resin and salicylic acid metal complex are dispersed in an aqueous medium (3) Core Step of forming a shell layer on the surface of the core resin particles by adding the shell resin particle dispersion to the resin particle dispersion (coagulation / fusion process)
(3-1) A step of mixing the colorant particle dispersion and the core resin particle dispersion, and aggregating and fusing the colorant particles and the core resin particles to form toner core particles. (3-2) Toner core The shell resin particle dispersion is added to the particle dispersion, and the shell resin particles are aggregated and fused on the surface of the toner core particles to form a shell layer that covers the surface of the toner core particles. A step of preparing a dispersion of toner base particles having toner (4) a step of filtering the toner base particles from the dispersion (aqueous medium) of toner base particles to remove a surfactant (washing step)
(5) Step of drying toner base particles (drying step)
(6) Step of adding toner to toner base particles to make toner (external additive treatment step)

<Step (0)>
In this step, a colorant particle dispersion in which colorant particles are dispersed in an aqueous medium is prepared.
A dispersion of colorant particles can be prepared by dispersing a colorant in an aqueous medium. The dispersion treatment of the colorant is preferably performed in a state where the surfactant concentration in the aqueous medium is equal to or higher than the critical micelle concentration because the colorant is uniformly dispersed. A known disperser can be used as a disperser used for the dispersion treatment of the colorant. Moreover, as a surfactant which can be used, a publicly known thing can be used.

<Colorant>
As the colorant used in the present invention, carbon black, a magnetic material, 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.
As the magnetic material, ferromagnetic metals such as iron, nickel and cobalt, alloys containing these metals, and compounds of ferromagnetic metals such as ferrite and magnetite can be used.

Examples of the dye include C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95, etc. can be used, and mixtures thereof can also be used.
Examples of the pigment include C.I. I. Pigment Red 5, 48: 1, 48: 3, 53: 1, 57: 1, 81: 4, 122, 139, 144, 149, 166, 177, 178, 222, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, 185, C.I. I. Pigment green 7, C.I. I. Pigment Blue 15: 3, 15: 4, 60, and the like, and a mixture thereof can also be used.
The number average primary particle diameter varies depending on the type, but is preferably in the range of about 10 to 200 nm.

<Step (1)>
In this step, a core resin particle dispersion in which core resin particles containing a styrene-acrylic resin are dispersed in an aqueous medium is prepared.
As a method for dispersing the core resin particles, it is preferable to use an emulsion polymer particle dispersion obtained by emulsion polymerization.
The core resin particles may have a multilayer structure of two or more layers made of binder resins having different compositions. For the core resin particles having such a structure, for example, those having a two-layer structure are prepared by preparing a dispersion of resin particles by emulsion polymerization treatment (first-stage polymerization) according to a conventional method, and polymerizing the dispersion. An initiator and a polymerizable monomer are added, and this system can be obtained by a technique of polymerization treatment (second stage polymerization).

<Step (2)>
In this step, a shell resin particle dispersion in which a polyester resin-containing shell resin particle and a salicylic acid metal complex are dispersed in an aqueous medium is prepared.
For the dispersion of the salicylic acid metal complex into the polyester resin, the above-described phase inversion emulsification method is preferably used.

<Step (3-1)>
In this step, the colorant particle dispersion and the core resin particle dispersion are mixed, and the colorant particles and the core resin particles are aggregated and fused to form toner core particles.
As a method for aggregating and fusing the colorant particles and the core resin particles, a flocculant is added to the core resin particle dispersion and the colorant particle dispersion, and wax particles and other toner configurations are added as necessary. A dispersion liquid for agglomeration is prepared by mixing with a dispersion liquid of component particles, and the temperature is adjusted to cause aggregation and fusion in an aqueous medium to form a dispersion liquid of toner core particles.

In the step (3-1), 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, it is preferable to start heating the flocculating dispersion liquid as quickly as possible so as to be equal to or higher than the glass transition point of the resin composition. The reason for this is not clear, but the agglomeration state of the particles fluctuates with the passage of the standing time, and there is a possibility that the particle size distribution of the obtained toner core particles becomes unstable or the surface property fluctuates. Because there is. The standing time is usually within 30 minutes, preferably within 10 minutes.
Further, in the step (3-1), it is preferable to quickly raise the temperature by heating, and the rate of temperature rise is preferably 1 ° 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.
Furthermore, it is important to continue the fusion by holding the temperature of the aggregation dispersion liquid for a certain period of time after the aggregation dispersion liquid reaches a temperature equal to or higher than the glass transition temperature. Thereby, the growth and fusion of the colored particles can be effectively advanced, and the durability of the finally obtained toner core particles can be improved.

<Flocculant>
The flocculant used in the present invention is not particularly limited, but those selected from metal salts are preferably used. For example, a salt of a monovalent metal such as an alkali metal salt such as sodium, potassium or lithium, a salt of a divalent metal such as calcium, magnesium, manganese or copper, or a trivalent metal such as iron or aluminum Examples include 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 is particularly preferable. It is a metal salt.
When a divalent metal salt is used, agglomeration can be promoted with a smaller amount. These may be used alone or in combination of two or more.

<Wax>
Examples of the wax used in the present invention include low molecular weight polyethylene wax, low molecular weight polypropylene wax, Fischer-Tropsch wax, microcrystalline wax, hydrocarbon waxes such as paraffin wax, carnauba wax, pentaerythritol behenate, Examples thereof include ester waxes such as behenyl behenate and behenyl citrate. These can be used alone or in combination of two or more.
The content ratio of the wax is in the range of 2 to 20% by mass, preferably in the range of 3 to 18% by mass, and more preferably in the range of 4 to 15% by mass with respect to the total mass of the resin particles.
Further, the melting point of the wax is preferably in the range of 50 to 95 ° C. from the viewpoint of low-temperature fixability and releasability of the toner in electrophotography.

<Step (3-2)>
In this step, the shell resin particle dispersion is added to the toner core particle dispersion, and the shell resin particles are aggregated and fused on the surface of the toner core particles to form a shell layer that covers the surface of the toner core particles. Then, a dispersion of toner base particles having a core-shell structure is prepared.

<Step (4)>
In this step, the toner base particles are filtered off from the dispersion (aqueous medium) of the toner base particles prepared in the step (3-2), and the surfactant and the like are removed.

<Step (5)>
In this step, the toner base particles obtained in the step (4) are dried.

<Step (6)>
In this step, for the purpose of improving the fluidity and charging characteristics of the toner, an external additive is added to the toner base particles to obtain a toner.

<External additive>
Examples of the external additive used in the present invention include inorganic oxide fine particles such as silica fine particles, alumina fine particles and titanium oxide fine particles, inorganic stearic acid compound fine particles such as aluminum stearate fine particles and zinc stearate fine particles, or titanic acid. Examples thereof include inorganic fine particles such as inorganic titanic acid compound fine particles such as strontium and zinc titanate.
In particular, it is preferable to use silica fine particles having an average particle diameter of 70 to 150 nm from the viewpoints of durability, cleaning properties and transferability.
These inorganic fine particles are preferably those subjected to surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil, or the like from the viewpoint of heat resistance and environmental stability.
The amount of the external additive added is in the range of 0.05 to 5 parts by mass, preferably in the range of 0.1 to 3 parts by mass with respect to 100 parts by mass of the toner base particles. Various external additives may be used in combination.
Examples of the method for adding the external additive include a dry method in which the external additive is added in powder form to the dried toner base particles. Examples of the mixing device include mechanical mixing devices such as a Henschel mixer and a coffee mill.

[Developer]
The toner of the present invention can be used as a two-component developer composed of a carrier and a toner, or as a non-magnetic one-component developer composed only of a toner.
Carriers that are magnetic particles used when used as a two-component developer are conventionally known materials such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead. It is possible to use. Among these, ferrite particles are preferable.
As the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, a resin-dispersed carrier in which magnetic fine powder is dispersed in a binder resin, and the like may be used.
The volume average particle diameter of the carrier is preferably in the range of 15 to 100 μm, more preferably in the range of 25 to 80 μm.

[Image forming apparatus]
An image forming apparatus in which the toner of the present invention is used comprises an electrostatic latent image carrier (typically an electrophotographic photoreceptor, hereinafter simply referred to as a photoreceptor), a charging unit, an exposing unit, and a toner. And a transfer means for transferring a toner image formed by the development means to a transfer material via an intermediate transfer member.
In particular, it is effective to be used for a color image forming apparatus that sequentially transfers a toner image on a photosensitive member to an intermediate transfer member, a tandem color image forming device in which a plurality of photosensitive members of respective colors are arranged in series on the intermediate transfer member, and the like. is there.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
1. Preparation of Toner 1 Core resin: Styrene-acrylic resin Shell resin: Polyester resin containing salicylic acid metal complex

(0) Preparation of Colorant Particle Dispersion Solution 90 parts by mass of sodium dodecyl sulfate was stirred and dissolved in 1600 parts by mass of ion-exchanged water. While stirring this solution, 420 parts by mass of carbon black “Mogal L” (manufactured by Cabot) was gradually added.
Subsequently, a “colorant particle dispersion” in which the colorant particles were dispersed was prepared by performing a dispersion treatment using a stirrer “CLEARMIX” (manufactured by M Technique Co., Ltd.). When the particle size of this dispersion was measured using a nanotrack particle size distribution analyzer UPA-EX150 (manufactured by Nikkiso Co., Ltd.), the average particle size was 117 nm.

(1) Preparation of resin particle dispersion for core (1-1) First stage polymerization An anionic surfactant “lauryl” was previously prepared in a reaction vessel equipped with a stirrer, a temperature sensor, a temperature controller, a cooling pipe and a nitrogen introducing device. An anionic surfactant solution in which 2.0 parts by mass of “sodium sulfate” was dissolved in 2900 parts by mass of ion-exchanged water was charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. .
To this surfactant solution, 9.0 parts by mass of a polymerization initiator “potassium persulfate: KPS” was added and the internal temperature was adjusted to 78 ° C.
Solution (1)
Styrene 540 parts by weight n-butyl acrylate 270 parts by weight Methacrylic acid 65 parts by weight n-octyl mercaptan 17 parts by weight of solution (1) was added dropwise over 3 hours, and after completion of the addition, heating and stirring at 78 ° C. for 1 hour Thus, polymerization (first stage polymerization) was performed to prepare “a dispersion of resin particles [a1]”.

(1-2) Second-stage polymerization: formation of intermediate layer In a flask equipped with a stirrer,
Solution (2)
Styrene 94 parts by weight n-butyl acrylate 60 parts by weight Methacrylic acid 11 parts by weight n-octyl mercaptan 5 parts by weight Paraffin wax (melting point: 73 ° C.) 51 parts by weight as a release agent was added, A monomer solution [2] was prepared by heating to 85 ° C. and dissolving.

  On the other hand, a surfactant solution in which 2 parts by mass of the anionic surfactant “sodium lauryl sulfate” was dissolved in 1100 parts by mass of ion-exchanged water was heated to 90 ° C. After adding 28 parts by mass of “dispersion of resin particles [a1]” in terms of solid content of resin particles [a1] to this surfactant solution, mechanical disperser “Clairemix” (M The above-mentioned monomer solution [2] was mixed and dispersed for 4 hours by Technic Co., Ltd. to prepare a dispersion containing emulsified particles having a dispersed particle diameter of 350 nm. To this dispersion was added an initiator aqueous solution in which 2.5 parts by mass of a polymerization initiator “KPS” was dissolved in 110 parts by mass of ion-exchanged water, and this system was polymerized by heating and stirring at 90 ° C. for 2 hours. (Second-stage polymerization) was performed to prepare “dispersion of resin particles [a11]”.

(1-3) Third-stage polymerization: formation of outer layer Start of dissolving 2.5 parts by mass of polymerization initiator “KPS” in 110 parts by mass of ion-exchanged water in the above “dispersion of resin particles [a11]” Aqueous agent aqueous solution is added and under the temperature condition of 80 ° C.
Solution (3)
Styrene 230 mass parts n-butyl acrylate 100 mass parts n-octyl mercaptan Solution (3) which consists of 5.2 mass parts was dripped over 1 hour. After completion of the dropwise addition, polymerization (third stage polymerization) was carried out by heating and stirring for 3 hours. Then, it cooled to 28 degreeC and prepared "the dispersion liquid of the core resin particle [A]" in which the core resin particle [A] was disperse | distributed in the anionic surfactant solution.

(2) Preparation of resin particle dispersion for shell (2-1) Preparation of polyester resin In a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, 316 parts by mass of bisphenol A propylene oxide 2 mol adduct, terephthalate 80 parts by weight of acid, 34 parts by weight of fumaric acid and 2 parts by weight of titanium tetraisopropoxide as a polycondensation catalyst were added in 10 portions, and the reaction was carried out for 10 hours while distilling off the water produced at 200 ° C. under a nitrogen stream I let you.
Subsequently, it was made to react under reduced pressure of 13.3 kPa (100 mmHg), and it pick_out | removed when the softening point became 104 degreeC. This is designated as polyester resin [a].
The polyester resin [a] had a Tg of 65 ° C., a number average molecular weight of 4500, and a weight average molecular weight of 13500.
Next, 430 parts by mass of xylene and 430 parts by mass of the polyester resin [a] were dissolved in an autoclave reaction vessel equipped with a thermometer and a stirrer, and after substitution with nitrogen, 86 parts by mass of styrene and 2-ethylhexyl acrylate 21. A mixed solution of 5 parts by mass, 0.75 part by mass of di-t-butyl peroxide and 100 parts by mass of xylene was dropped and polymerized at 170 ° C. for 3 hours, and further maintained at this temperature for 30 minutes.
Next, the solvent was removed to obtain a polyester resin [A] (shell resin).

(2-2) Preparation of Shell Particle Dispersion 100 parts by mass of polyester resin [A] as a resin for shell and zinc 3,5-di-tert-butylsalicylate (R ² = hydrogen, R ¹ , as a salicylic acid metal complex) R ³ = tert-butyl group) 15.0 parts by mass of (3% percentage of the total resin) was dissolved in ethyl acetate 400 parts by mass.
Subsequently, 25 mass parts of 5.0 mass% sodium hydroxide aqueous solution was added, and the resin solution was formed. This resin solution was put into a container having a stirrer, and 638 parts by mass of a 0.26% by mass aqueous sodium lauryl sulfate solution was added dropwise over 30 minutes while stirring the resin solution. During the dropping of the sodium lauryl sulfate aqueous solution, the liquid in the reaction vessel became cloudy, and after the entire amount of the sodium lauryl sulfate aqueous solution was dropped, an emulsion was formed in which the resin solution particles were uniformly dispersed.
Next, the emulsion was heated to 40 ° C., and ethyl acetate was distilled off under a reduced pressure of 150 hPa using a diaphragm vacuum pump “V-700” (manufactured by Nihon Büch) to obtain “resin for shell”. Dispersion 1 ”of particles [A] (a dispersion of polyester resin particles containing a salicylic acid metal complex) was obtained.

(3) Preparation of dispersion of toner base particles 1 (aggregation / fusion process)
Into a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling pipe, 288 parts by mass of "dispersion of resin particles for core [A]" in terms of solid content and 2000 parts by mass of ion-exchanged water are added and then 5 mol / liter. Of sodium hydroxide was added to adjust the pH to 10 at 25 ° C. Thereafter, 40 parts by mass of the “colorant particle dispersion” was added in terms of solid content.
Next, an aqueous solution in which 60 parts by mass of magnesium chloride was dissolved in 60 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring.
Thereafter, the temperature was raised after being allowed to stand for 3 minutes, and the temperature of the system was raised to 80 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 80 ° C. In this state, the particle size of the associated particles was measured with “Coulter Multisizer 3” (manufactured by Beckman Coulter), and when the volume-based median diameter (D ₅₀ ) reached 6.0 μm, “Shell Resin 72 parts by mass of Particle [A] Dispersion 1 ”in terms of solid content is added over 30 minutes, and when the supernatant of the reaction solution becomes transparent, 190 parts by mass of sodium chloride is added to 760 parts by mass of ion-exchanged water. The dissolved aqueous solution was added to stop particle growth.
Further, the temperature is raised and the mixture is heated and stirred in a state of 90 ° C. to advance the fusing of the particles, and the average circularity measurement apparatus “FPIA-2100” (manufactured by Sysmex) is used (HPF detection). When the average circularity reached 0.945, the mixture was cooled to 30 ° C. to prepare a “dispersion of toner base particle 1”.

(4) Washing step and (5) Drying step The particles produced in the step (3) (“dispersion of toner base particles 1”) are subjected to solid-liquid separation using a centrifuge, and a wet cake of toner base particles is obtained. Formed. The wet cake was washed with ion-exchanged water at 35 ° C. until the electric conductivity of the filtrate reached 5 μS / cm in the centrifuge. Thereafter, the toner was transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.) and dried until the water content became 0.5 mass% to prepare “toner base particle 1”.

(6) External additive treatment step In the above “toner base particle 1”, the hydrophobic silica having a number average primary particle diameter of 12 nm is 1% by mass, and the number average primary particle diameter is 80 nm. Using a mixed system of 3% by mass, hydrophobic silica and hydrophobic titania (number average primary particle size = 20 nm) 0.3% by mass of this mixed system were added and mixed with a Henschel mixer to obtain “toner 1 Was made.

2. Production of Toners 2 to 5 In “(2-2) Preparation of Resin Particle Particle Dispersion for Shell” in Production of Toner 1 above, zinc 3,5-di-tert-butylsalicylate (R ² = hydrogen, R ¹ , R “Toners 2 to 5” were prepared in the same manner as in the preparation of the toner 1 except that the salicylic acid metal complex shown in Table 1 was used instead of ( ³ = tert-butyl group). The content (mass%) of the salicylic acid metal complex with respect to the total resin was as shown in Table 1.

3. Production of Toner 6 In “(2-2) Preparation of Resin Particle Particle Dispersion for Shell” in the production of toner 1 described above, zinc 3,5-di-tert-butylsalicylate (R ² = hydrogen, R ¹ , R ³ = “Toner 6” was prepared in the same manner as in the preparation of toner 1 except that no tert-butyl group was added.

4). Production of Toner 7 In “(2-2) Preparation of Resin Particle Particle Dispersion for Shell” in the production of toner 1 described above, zinc 3,5-di-tert-butylsalicylate (R ² = hydrogen, R ¹ , R ³ = The same procedure as in the preparation of the toner 1 except that aluminum 3,5-di-tert-butylsalicylate (R ² = hydrogen, R ¹ , R ³ = tert-butyl group) was used instead of (tert-butyl group). Thus, “Toner 7” was produced.
However, since the aluminum 3,5-di-tert-butylsalicylate used is not compatible with the shell resin (polyester resin), it is difficult to form a toner.

5. Production of Toner 8 In the production of the toner 1, a styrene-acrylic resin and a polyester resin (containing a salicylic acid metal complex) were aggregated from the beginning, and a toner 8 having no core / shell structure was produced by the following procedure.
(1) Preparation of dispersion of toner base particles 8 (aggregation / fusion process)
In a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube, 288 parts by mass of “dispersion liquid of core resin particles [A]” and “dispersion liquid 1 of shell resin particles [A]” in terms of solid content After 72 parts by mass in terms of solid content and 2000 parts by mass of ion-exchanged water were added, a 5 mol / liter sodium hydroxide aqueous solution was added to adjust the pH to 10 at 25 ° C. Thereafter, 40 parts by mass of the “colorant particle dispersion” was added in terms of solid content.
Next, an aqueous solution in which 60 parts by mass of magnesium chloride was dissolved in 60 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring.
Thereafter, the temperature was raised after being allowed to stand for 3 minutes, and the temperature of the system was raised to 80 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 80 ° C. In this state, the particle size of the associated particles was measured with “Coulter Multisizer 3” (manufactured by Beckman Coulter), and when the median diameter (D ₅₀ ) on the volume basis became 6.0 μm, 190 mass of sodium chloride was obtained. Particulate growth was stopped by adding an aqueous solution having a part dissolved in 760 parts by mass of ion-exchanged water.
Further, the temperature is raised and the mixture is heated and stirred in a state of 90 ° C. to advance the fusing of the particles, and the average circularity measurement apparatus “FPIA-2100” (manufactured by Sysmex) is used (HPF detection). When the average circularity reached 0.945, the mixture was cooled to 30 ° C. to prepare a “dispersion of toner base particle 8”.

  The subsequent manufacturing steps (cleaning step, drying step, and external additive treatment step) were performed in the same manner as in the preparation of the toner 1 to produce “toner 8”.

6). Production of toner 9 In “(2-2) Preparation of resin particle dispersion for shell” in the production of toner 1 described above, zinc 3,5-di-tert-butylsalicylate (R ² = hydrogen, R ¹ , R ³ = The same procedure as in the preparation of toner 1 except that calcium 3,5-di-tert-butylsalicylate (R ² = hydrogen, R ¹ , R ³ = tert-butyl group) was used instead of (tert-butyl group). In this way, “Toner 9” was produced.

7). Preparation of Developers 1-9 100 parts by mass of ferrite core and 5 parts by mass of copolymer resin particles of cyclohexyl methacrylate / methyl methacrylate (copolymerization ratio 5/5) were charged into a high-speed mixer equipped with stirring blades. The mixture was stirred and mixed at 0 ° C. for 30 minutes to form a resin coat layer on the surface of the ferrite core by the action of mechanical impact force, and a carrier having a volume-based median diameter (D ₅₀ ) of 50 μm was obtained.
The volume-based median diameter (D ₅₀ ) of the carrier was measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by Sympathic) equipped with a wet disperser.
Each of the prepared toners is added to the carrier so that the toner concentration becomes 6% by mass, and the toner is put into a micro V-type mixer (Tsutsui Rikenki Co., Ltd.), mixed at a rotational speed of 45 rpm for 30 minutes, Developers 1 to 9 "were prepared.

8). For each toner measured production of distribution of salicylic acid metal complex _(S 2 / S _1), to measure the distribution of salicylic acid metal complex _(S 2 / S _1).
Here, a solution in which the toner base particles are dissolved in methyl ethyl ketone is referred to as solution (1), a solution in which the toner base particles are dissolved in methanol is referred to as solution (2), and the respective solutions (1) and (2) are the same by high performance liquid chromatography. When measured under the conditions, the peak area of the peak (P ₂ ) derived from the salicylic acid derivative obtained in the solution (2) is S ₂ and derived from the salicylic acid derivative having the same retention time as P _{2 in the} solution (1) The peak area of the peak (P ₁ ) to be performed was defined as S ₁ . The HPLC measurement conditions and S ₂ / S ₁ calculation method were as described above, and the results are shown in Table 1 below.

9. Evaluation method of toner Each of the produced toners (developers) was evaluated as shown below, and the results are shown in Table 2 below.
(1) Cover After printing 2000 sheets of A4 size transfer paper at a normal temperature and humidity (20 ° C., 50% RH) at a printing rate of 3% with “bizhub Press C8000” manufactured by Konica Minolta Business Technologies, the printing rate is 50 % 2000 A4 size transfer paper was printed. After the printing of a total of 4000 sheets, the fog measurement was performed.
In the fog measurement, 20 areas of the A4 size of the white paper of the image support are measured, and the average value is used as the white paper density. Next, for the white background portion of the 4000th evaluation formed image, 20 absolute positions are similarly obtained. The image density was measured and averaged, and the value obtained by subtracting the blank paper density from this average density was evaluated as the fog density. If the fog density was 0.01 or less, the fog was accepted. Density measurement was performed using a reflection densitometer “RD-918” (manufactured by Macbeth).
◎: Less than 0.003 ○: 0.003 to less than 0.006 Δ: 0.006 to 0.010
X: Value greater than 0.010 Good fog characteristics even when the printing rate fluctuates from a low printing rate to a high printing rate means that the rising of charging is fast and stable.

(2) Heat resistance 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 the lid is removed. It was left in an environment of 55 ° C. and 35% RH for 2 hours.
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. The vibration intensity was adjusted to a feed width of 1 mm, and vibration was applied for 10 seconds. Thereafter, the ratio (mass%) of the toner amount remaining on the sieve was measured. The toner aggregation rate is a value calculated by the following formula.
Toner aggregation rate (%) = residual toner mass on sieve (g) /0.5 (g) × 100
The heat resistance of the toner was evaluated according to the criteria described below.
A: The toner aggregation rate is less than 10% by mass (the heat resistance of the toner is extremely good).
○: The toner aggregation rate is less than 10 to 15% by mass (good heat resistance of the toner)
(Triangle | delta): Toner aggregation rate 15-20 mass% (heat resistance of a toner is favorable)
X: The toner aggregation rate exceeds 20% by mass (the toner has poor heat resistance and cannot be used)

(3) Crush resistance The developer was introduced into the developer used in “bizhub PRO C6500” manufactured by Konica Minolta Business Technologies, and driven at a speed of 600 rpm for 3.5 hours by a single drive. . Therefore, the developer in the developing unit was sampled, and the toner particle size distribution was measured with Multisizer 3 (manufactured by Beckman Coulter). The toner increase rate (mass%) of 2.5 μm or less was calculated and evaluated for resistance to crushing as compared with the toner before the developing device was charged. The higher the increase rate, the easier the crushing occurs in the developing device. The evaluation criteria are as follows.
◎: Increase rate is 3% or less ○: Increase rate is over 3% but is 7% or less △: Increase rate is over 7% but is 10% or less ×: Increase rate is over 10%

  From the results shown in Table 2, it was confirmed that Examples 1 to 6 were better in terms of fogging, heat resistance and crush resistance than Comparative Examples 1 to 3.

Claims (6)

A method for producing a toner for developing an electrostatic image containing toner base particles having a core-shell structure,
The toner base particles are particles having a structure in which a core resin containing a styrene-acrylic resin is coated with a shell resin containing a polyester resin graft-modified with a styrene-acrylic resin, and at least the shell resin Containing a salicylic acid metal complex consisting of a salicylic acid derivative and a divalent metal in the part,
A toner production method comprising at least the following steps (1) to (3):
(1) Step of preparing a core resin particle dispersion in which core resin particles containing the styrene-acrylic resin are dispersed in an aqueous medium (2) Shell containing the polyester resin in an aqueous medium Step (3) of preparing a resin particle dispersion for shell in which resin particles for metal and the metal salicylate complex are dispersed (3) Adding the resin particle dispersion for shell to the core resin particle dispersion, Forming a shell layer on the surface of resin particles The step (2) of preparing a resin particle dispersion for a shell contains the salicylic acid metal complex in the polyester resin in a state of emulsified fine particles using a phase inversion emulsification method. 2. A method for producing a toner for developing an electrostatic charge image according to 1 . The salicylic acid metal complex, according to claim 1 or method of manufacturing a toner according to claim 2 characterized by having a structure represented by the following general formula (1).

[In General Formula (1), M represents any of magnesium, zinc, zirconium, copper, iron, calcium, nickel, or cobalt. R ¹ , R ² and R ³ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms. m represents 2 and n represents 1. ] A solution in which the toner base particles are dissolved in methyl ethyl ketone is referred to as solution (1), and a solution in which methanol is dissolved in methanol is referred to as solution (2).
When the respective solutions (1) and (2) were measured under the same conditions by high performance liquid chromatography, the peak area of the peak (P ₂ ) derived from the salicylic acid derivative obtained in the solution (2) was expressed as S _2. with a peak area of a peak (P ₁₎ derived from a salicylic acid derivative having the same retention time as P ₂ solution (1) When S _1, claim 1, characterized by satisfying the following formula (a) The method for producing a toner for developing an electrostatic image according to claim 3 .
Formula (A): 0.8 <S ₂ / S ₁ ≦ 1 The salicylic acid metal complex, the styrene - acrylic resin and the styrene - based on the total resin graft-modified polyester resin with an acrylic resin, characterized by Rukoto is contained in the range of 0.1 to 10 mass% The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 4 . As the external additive, the preparation of toner according to any one of up to claims 1 to 5, characterized in Rukoto is contained silica in the range of average particle size 70~150nm Way .