JP2017138542A - Manufacturing method of toner for electrophotography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a toner for electrophotography excellent simultaneously in low temperature fixiability, storage stability under a high temperature and high humidity condition, and wax dispersibility.SOLUTION: Provided is a method for manufacturing a toner for electrophotography which contains particles obtained by fusing aggregate particles obtained by aggregating an aqueous dispersion which is a mixture of an aqueous dispersion of a binder resin for the toner and a surfactant, where the aggregate particles contain wax which is a releasing agent, the binder resin contains a polyester resin which is a polycondensation product having an alcohol component including an aliphatic diol having a carbon number of 2 to 4 and a carboxylic acid component, an acid value of the polyester resin is not less than 5 mg KOH/g and not more than 10 mg kOH/g, the aqueous dispersion is obtained via the following steps 1, 2, 3, and 4, the surfactant is an anionic surfactant having an oxyethylene group, an amount of addition of the surfactant to the polyester resin in step 4 is 1 to 10 mass%. The step 1: a step of obtaining a mixture by mixing at least the binder resin, an organic solvent, and a neutralizer; step 2: a step of obtaining a resin dispersion by mixing water into the mixture obtained by the step 1; step 3: a step of obtaining the aqueous dispersion of the binder resin by removing the organic solvent from the resin dispersion obtained by the step 2; step 4: a step of mixing the surfactant into the aqueous dispersion obtained by the step 3.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing an electrophotographic toner, and relates to a method for producing an electrophotographic toner used in an electrophotographic method, an electrostatic recording method, an electrostatic printing method and the like.

In recent years, there has been a demand for a toner having both low-temperature fixability and storability due to speeding up and energy saving of a machine. On the other hand, as a toner production method, an emulsion aggregation method capable of reducing the particle size and separating functions such as a core shell has become mainstream. As binder resins, polyester binder resins having excellent low-temperature fixability have been used instead of styrene-acrylic resins.
In the production of toner by the emulsion aggregation method, first, an aqueous dispersion is prepared by emulsifying a resin, and then the aggregated particles obtained by aggregation are fused to form toner particles. As the polyester emulsification method, a phase inversion emulsification method that can obtain a fine and uniform aqueous dispersion without applying high shear is preferably used.
In recent years, binder resins containing plant-derived monomers have been developed in order to reduce CO ₂ when toner is discharged. However, the plant-derived monomer capable of polycondensation has a problem that the storage stability of the toner is deteriorated as compared with the case where a petroleum-derived monomer is used.

  On the other hand, a technique for improving the storage stability of a toner by containing an aliphatic polyhydric alcohol having a secondary carbon atom bonded with a hydroxyl group as an alcohol component is disclosed (for example, Patent Documents 1 to 3). See).

JP 2010-107674 A JP 2010-107675 A JP 2010-128212 A

However, emulsion aggregation toners produced from the resins disclosed in Patent Documents 1 to 3 are low-temperature fixability, storage stability under high-temperature and high-humidity conditions (hereinafter also referred to as HH conditions), release agents added during aggregation, and the like. Either of the dispersibility of the wax that is the mold is insufficient.
Accordingly, the present invention provides a toner having excellent low-temperature fixability, storage stability under high-temperature and high-humidity conditions, and wax dispersibility simultaneously in an emulsion aggregation toner produced from a polyester resin obtained by polycondensation of plant-derived monomers. It is to provide a method.

The present invention relates to the following method for producing an electrophotographic toner.
A method for producing an electrophotographic toner comprising particles obtained by fusing agglomerated particles obtained by aggregating an aqueous dispersion that is a mixture of an aqueous dispersion of a binder resin for a toner and a surfactant,
The agglomerated particles contain a wax as a release agent;
The binder resin contains a polyester resin that is a polycondensate of an alcohol component containing an aliphatic diol having 2 to 4 carbon atoms and a carboxylic acid component, and the acid value of the polyester resin is 5 mgKOH / g or more and 10 mgKOH / g or less,
The aqueous dispersion is obtained through the following steps 1, 2, 3 and 4,
Production of an electrophotographic toner, wherein the surfactant is an anionic surfactant having an oxyethylene group, and the amount of the surfactant added to the polyester resin in Step 4 is 1% by mass or more and 10% by mass or less. Method.
Step 1: A step of mixing at least a binder resin, an organic solvent and a neutralizing agent to obtain a mixture.
Step 2: A step of mixing the mixture obtained in Step 1 with water to obtain a resin dispersion.
Step 3: A step of obtaining an aqueous dispersion of the binder resin by removing the organic solvent from the resin dispersion obtained in Step 2.
Step 4: A step of mixing a surfactant with the aqueous dispersion obtained in Step 3.

  According to the present invention, a toner can be obtained by controlling the cohesiveness of a polyester emulsion, and the electrophotographic toner obtained by the production method of the present invention has a low temperature fixability, storage stability under high temperature and high humidity conditions, and a wax. Excellent dispersibility.

  The reason why the electrophotographic toner obtained by the production method of the present invention is excellent in low-temperature fixability and storage stability is not necessarily clear, but can be considered as follows. According to the present invention, by controlling the cohesiveness of the polyester emulsion, a toner having a uniform particle diameter can be produced without the polyester emulsion aggregating rapidly. It is considered that the low temperature fixability and the storage stability are excellent because the low temperature fixability due to the large particle size toner and the storage stability due to the small particle size toner do not deteriorate. In addition, it is considered that the wax used as a release agent is evenly taken into the toner without aggregation of the polyester resin by controlling the cohesiveness of the polyester emulsion, thereby contributing to low-temperature fixability and storage stability.

  Regarding the aggregation control mechanism of the polyester emulsion, it is considered that the adsorption form of the surfactant to the polyester emulsion is involved in the aggregation stability. That is, it is considered that using a specific amount of an anionic surfactant having an oxyethylene group contributes to aggregation stability. Specifically, the cohesiveness is considered to change depending on whether the oxyethylene group of the surfactant is taken into the emulsion or in water. Here, when the emulsion surface is hydrophobized by lowering the acid value of the polyester resin or lowering the pH of the emulsion and neutralizing the dissociated acid ends, the oxyethylene group of the hydrophilic surfactant Is thought to be less likely to be present in the emulsion. It is estimated that the presence of oxyethylene groups in water increases the repulsion between emulsions and contributes to stabilization of aggregation.

The method for producing an electrophotographic toner of the present invention includes particles obtained by fusing aggregated particles obtained by aggregating an aqueous dispersion that is a mixture of an aqueous dispersion of a binder resin for a toner and a surfactant. A method for producing an electrophotographic toner, wherein the aggregated particles contain a wax as a release agent, and the binder resin contains an alcohol component and an carboxylic acid component containing an aliphatic diol having 2 to 4 carbon atoms. A polyester resin that is a polycondensate of the polyester resin, the acid value of the polyester resin is 5 mgKOH / g or more and 10 mgKOH / g or less, and the aqueous dispersion is obtained through the following steps 1, 2, 3, and 4, The surfactant is an anionic surfactant having an oxyethylene group, and the amount of the surfactant added to the polyester resin in Step 4 is 1% by mass or more and 10% by mass or less.
Step 1: A step of mixing at least a binder resin, an organic solvent and a neutralizing agent to obtain a mixture.
Step 2: A step of mixing the mixture obtained in Step 1 with water to obtain a resin dispersion.
Step 3: A step of obtaining an aqueous dispersion of the binder resin by removing the organic solvent from the resin dispersion obtained in Step 2.
Step 4: A step of mixing a surfactant with the aqueous dispersion obtained in Step 3.

  Furthermore, the method for producing an electrophotographic toner of the present invention includes a step of obtaining an aqueous dispersion of a binder resin for toner through the steps 1 to 4 (a step of producing an aqueous dispersion of a binder resin), the aqueous dispersion A step of aggregating the release agent particles in the aqueous dispersion containing the resin particles therein and the wax as the release agent to obtain aggregated particles (aggregation step), and fusing the resulting aggregated particles (union) A production method including a step (fusing (union) step) of obtaining fused particles (union particles) by heating is preferable.

In the present invention, the “aqueous” in the “aqueous dispersion” and the “aqueous dispersion” may contain a solvent such as an organic solvent, but preferably contains 50% by mass or more, preferably 70% by mass of water. More preferably, it contains 90% by mass or more, more preferably 99% by mass or more.
When mixing / dispersing the binder resin, organic solvent, surfactant, neutralizing agent, and water, use chemical dispersion methods such as phase inversion emulsification, and mechanical dispersion methods such as homogenizers and ultrasonic dispersers. Can do.

[Process for producing aqueous dispersion of binder resin]
[Step 1]
Step 1 is a step of obtaining a mixture by mixing at least a binder resin, an organic solvent, and a neutralizing agent.

(Binder resin)
The binder resin used in the present invention contains a polycondensation resin obtained by polycondensation of a specific alcohol component and a specific carboxylic acid component. The content of the polycondensation resin in the binder resin is preferably 65% by mass or more, more preferably 75% by mass, from the viewpoint of improving low temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. % Or more, more preferably 85% by mass or more, and still more preferably substantially 100% by mass.

The polycondensation resin used in the present invention is a polyester resin. The polyester resin may be an amorphous resin or a crystalline polyester. From the viewpoint of improving the low temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility, the polyester resin may be used. It is preferable that it is a quality resin. Here, the crystallinity of a resin such as polyester is the ratio between the softening point and the maximum endothermic peak temperature measured by a differential scanning calorimeter (DSC), that is, the crystallinity index defined by “softening point / maximum endothermic peak temperature”. Represented by Generally, when the crystallinity index exceeds 1.4, the resin is amorphous, and when it is less than 0.6, the crystallinity is low and there are many amorphous portions. In the present invention, the “crystalline polyester” means a polyester having a crystallinity index of 0.6 or more and 1.4 or less, preferably 0.8 or more and 1.2 or less, more preferably 0.9 or more and 1.1 or less. “Amorphous resin” refers to a resin having a crystallinity index of more than 1.4 or less than 0.6.
The above “maximum endothermic peak temperature” refers to the temperature of the peak on the highest temperature side among the endothermic peaks observed under the measurement method conditions described in the examples. If the maximum peak temperature is within 20 ° C from the softening point, the maximum peak temperature is the melting point of the crystalline polyester, and the peak with a difference from the softening point exceeding 20 ° C is a peak due to the glass transition of the amorphous resin. And
In the present invention, the crystallinity of the polyester resin can be adjusted by the type and ratio of raw material monomers, production conditions (for example, reaction temperature, reaction time, cooling rate) and the like.

<Carboxylic acid component>
Examples of the carboxylic acid component that can constitute the polyester resin include aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and trivalent or higher polyvalent carboxylic acids. The carboxylic acid component includes not only a free acid but also an anhydride that decomposes during the reaction to produce an acid, and an alkyl ester having 1 to 3 carbon atoms.
The aliphatic dicarboxylic acid preferably has 2 to 18 carbon atoms, more preferably 8 to 12 carbon atoms, from the viewpoint of improving low-temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. Specific examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,10- A decanedicarboxylic acid is mentioned. Examples of the aliphatic dicarboxylic acid include succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms such as dodecyl succinic acid, dodecenyl succinic acid, and octenyl succinic acid. . Specific examples of the aromatic dicarboxylic acid include phthalic acid, isophthalic acid, and terephthalic acid. Specific examples of the trivalent or higher polyvalent carboxylic acid include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid. An acid (pyromellitic acid) is mentioned. These can be used alone or in combination of two or more. Among these, at least one selected from the group consisting of terephthalic acid, trimellitic acid anhydride, and dodecenyl succinic acid anhydride from the viewpoint of improving low-temperature fixability of toner, storage stability under high temperature and high humidity, and wax dispersibility. Is preferred.

<Alcohol component>
The alcohol component that can constitute the polyester resin includes 2 to 4 carbon atoms from the viewpoint of improving CO ₂ reduction during toner discharge, low temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. Of aliphatic diols are used. The aliphatic diol is preferably a plant-derived product.
Examples of the aliphatic diol having 2 to 4 carbon atoms include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4- Examples include butanediol, 2,3-butanediol, and 1,4-butenediol. These can be used alone or in combination of two or more. Among these, from the viewpoint of improving low-temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility, 1,2-propanediol is preferably included, and 1,2-propanediol and ethylene glycol are preferable. Alternatively, a combination with 1,2-butanediol is more preferable, and a combination of 1,2-propanediol and 1,4-butanediol is more preferable.

As an alcohol component which can comprise a polyester resin, you may contain alcohol other than C2-C4 aliphatic diol within the range which does not impair the effect of this invention. Examples of such alcohols include aliphatic diols having 5 or more carbon atoms, aromatic alcohols, and trihydric or higher alcohols.
Examples of the aliphatic diol having 5 or more carbon atoms include 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10- Examples include decanediol and 1,12-dodecanediol. Examples of the aromatic alcohol include polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, and the like Bisphenol A alkylene (2 to 3 carbon atoms) oxide (average added mole number 1 to 10) adducts. Examples of trihydric or higher alcohols include glycerol (also referred to as glycerin), pentaerythritol, trimethylolpropane, and the like.

  The content of the aliphatic diol having 2 to 4 carbon atoms is preferably 80 mol% or more, more preferably 85 mol% or more, and still more preferably 90 mol% or more in the alcohol component from the viewpoint of low-temperature fixability of the toner. More preferably, it is substantially 100 mol%.

  In addition, from the viewpoint of molecular weight adjustment and physical property adjustment, the alcohol component may appropriately contain a monovalent alcohol, and the carboxylic acid component may appropriately contain a monovalent carboxylic acid compound.

<Molar ratio of alcohol component to carboxylic acid component>
The molar ratio of the alcohol component and the carboxylic acid component (carboxylic acid component / alcohol component), which is a raw material monomer for the polycondensation reaction, is preferably 0.5 or more, more preferably from the viewpoint of reactivity, molecular weight adjustment, and physical property adjustment. It is 0.6 or more, more preferably 0.7 or more, and preferably 1.5 or less, more preferably 1.3 or less, still more preferably 0.9 or less.

<Method for producing polyester resin>
The polyester resin is obtained by a polycondensation reaction between an alcohol component and a carboxylic acid component. The polycondensation reaction is preferably performed in the presence of an esterification catalyst, and is more preferably performed in the presence of an esterification catalyst and a pyrogallol compound from the viewpoints of reactivity, molecular weight adjustment, and resin physical property adjustment.

<Esterification catalyst>
Examples of the esterification catalyst suitably used for the polycondensation reaction include a titanium compound and a tin (II) compound having no Sn—C bond, and these should be used alone or in combination of two or more. Can do.

  As the titanium compound, a titanium compound having a Ti—O bond is preferable, and a compound having an alkoxy group, an alkenyloxy group or an acyloxy group having 1 to 28 carbon atoms in total is more preferable.

  Examples of the tin (II) compound having no Sn—C bond include a tin (II) compound having a Sn—O bond, a tin (II) compound having a Sn—X (X represents a halogen atom) bond, and the like. Preferred is a tin (II) compound having a Sn-O bond, and among them, di (2-ethylhexanoic acid) tin (II) is more preferable from the viewpoints of reactivity, molecular weight adjustment, and resin physical property adjustment. .

  The abundance of the esterification catalyst is preferably 0.01 parts by mass or more, more preferably 100 parts by mass with respect to the total amount of alcohol component and carboxylic acid component, from the viewpoints of reactivity, molecular weight adjustment, and resin physical property adjustment. Is 0.1 parts by mass or more, and preferably 1 part by mass or less, more preferably 0.6 parts by mass or less.

<Pyrogallol compound>
A pyrogallol compound has a benzene ring in which three hydrogen atoms adjacent to each other are substituted with a hydroxyl group, and pyrogallol, gallic acid, gallic acid ester, 2,3,4-trihydroxybenzophenone, Examples include benzophenone derivatives such as 3,4-tetrahydroxybenzophenone, catechin derivatives such as epigallocatechin and epigallocatechin gallate, and gallic acid is preferred from the viewpoint of reactivity.
The abundance of the pyrogallol compound in the polycondensation reaction is preferably 0.001 part by mass or more with respect to 100 parts by mass of the total amount of the alcohol component and carboxylic acid component subjected to the polycondensation reaction from the viewpoint of reactivity. Preferably it is 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 1 part by mass or less, more preferably 0.4 parts by mass or less, still more preferably 0.2 parts by mass or less, More preferably, it is 0.1 mass part or less. Here, the abundance of the pyrogallol compound means the total amount of the pyrogallol compound subjected to the polycondensation reaction.
The mass ratio of the pyrogallol compound and the esterification catalyst (pyrogallol compound / esterification catalyst) is preferably 0.01 or more, more preferably 0.02 or more, and further preferably 0.03 or more, from the viewpoint of reactivity. And preferably 0.5 or less, more preferably 0.3 or less, still more preferably 0.2 or less, and still more preferably 0.15 or less.

The polycondensation reaction between the alcohol component and the carboxylic acid component can be performed, for example, at a temperature of 120 ° C. or higher and 250 ° C. or lower in the presence of the esterification catalyst in an inert gas atmosphere. From the viewpoint of reactivity, the reaction temperature is preferably 140 ° C. or higher, more preferably 160 ° C. or higher, further preferably 180 ° C. or higher, more preferably 200 ° C. or higher, and preferably 245 ° C. or lower, more preferably It is 230 degrees C or less, More preferably, it is 220 degrees C or less, More preferably, it is 210 degrees C or less.
In addition, for example, all monomers are charged together to increase the strength of the resin, or divalent monomers are first reacted to reduce low molecular weight components, and then trivalent or higher monomers are added and reacted. Etc. may be used. Further, the reaction may be accelerated by reducing the pressure of the reaction system in the latter half of the polymerization.

<Physical properties of binder resin>
The softening point of the binder resin used in the present invention is preferably 60 ° C. or higher, more preferably 80 ° C. or higher, from the viewpoint of improving low-temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. More preferably, it is 110 ° C. or higher, more preferably 120 ° C. or higher, and preferably 160 ° C. or lower, more preferably 150 ° C. or lower, still more preferably 140 ° C. or lower, and further preferably 130 ° C. or lower.
In addition, the glass transition temperature of the binder resin used in the present invention is preferably 45 ° C. or more, more preferably from the viewpoint of improving low temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. It is 50 ° C. or higher, and preferably 85 ° C. or lower, more preferably 80 ° C. or lower, and further preferably 70 ° C. or lower. The glass transition temperature is a physical property peculiar to an amorphous resin, and is distinguished from the maximum peak temperature of heat of fusion.

  The number average molecular weight of the binder resin is preferably 1,000 or more, more preferably 2,000 or more, from the viewpoint of improving the low-temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. And preferably 6,000 or less, more preferably 5,000 or less. Further, the weight average molecular weight is preferably 6,000 or more, more preferably 8,000 or more, and still more preferably, from the viewpoint of improving low-temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. It is 10,000 or more, and preferably 1,000,000 or less, more preferably 700,000 or less, and further preferably 500,000 or less. The number average molecular weight and the weight average molecular weight are both values obtained by measuring the tetrahydrofuran-soluble content.

The acid value of the binder resin is 5 mg KOH / g or more, preferably 5.5 mg KOH / g or more, more preferably from the viewpoint of improving low temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. 6 mgKOH / g or more, and 10 mgKOH / g or less, preferably 9.8 mgKOH / g or less, more preferably 9.5 mgKOH / g or less.
The softening point, glass transition temperature, number average molecular weight, weight average molecular weight, and acid value can be appropriately adjusted by adjusting the raw material monomer composition, molecular weight, catalyst amount, etc., or by selecting reaction conditions.

  The content of the binder resin in the mixture obtained in step 1 is preferably 35% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more, from the viewpoint of dissolving the binder resin in the organic solvent. Still more preferably, it is 70 mass% or more, Preferably it is 98 mass% or less, More preferably, it is 95 mass% or less, More preferably, it is 90 mass% or less, More preferably, it is 80 mass% or less.

(Organic solvent)
The organic solvent is preferably expressed by a solubility parameter (SP value: POLYMER HANDBOOK THIRD EDITION 1989 by John Wiley & Sons, Inc.) from the viewpoint of improving the solubility of the polyester resin and the dispersibility in the next step. 1.0 MPa ^1/2 or more, more preferably 16.0 MPa ^1/2 or more, still more preferably 17.0 MPa ^1/2 or more, and preferably 26.0 MPa ^1/2 or less, more preferably 24.0 MPa ^{1 An} organic solvent that is less than or equal to ^{2 and} more preferably 22.0 MPa ^1/2 is preferred.
Specific examples include alcohol solvents such as ethanol (26.0), isopropanol (23.5), and isobutanol (21.5); acetone (20.3), methyl ethyl ketone (19.0), methyl isobutyl ketone. Ketone solvents such as (17.2) and diethyl ketone (18.0); ether solvents such as dibutyl ether (16.5), tetrahydrofuran (18.6) and dioxane (20.5); ethyl acetate (18.6) and acetate solvents such as isopropyl acetate (17.4). The value in parentheses indicates the SP value. Among these, from the viewpoint of improving low-temperature fixability of toner, storage stability under high temperature and high humidity, and wax dispersibility, ketone solvents and acetate solvents are preferable, methyl ethyl ketone and ethyl acetate are more preferable, and methyl ethyl ketone is preferable. Is more preferable.

The amount of the organic solvent used is preferably 1 part by mass or more with respect to 100 parts by mass of the binder resin from the viewpoint of improving low temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. Preferably it is 2 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, and preferably 500 parts by mass or less, more preferably 150 parts by mass or less, still more preferably 100 parts by mass or less. More preferably, it is 80 mass parts or less, More preferably, it is 40 mass parts or less.
Further, the mass ratio of the binder resin to the organic solvent in Step 1 (binder resin / organic solvent) is from the viewpoint of improving the low-temperature fixability of the toner, the storage stability under high temperature and high humidity, and the wax dispersibility. Preferably from 1/5 to 1 / 0.01, more preferably from 1 / 1.5 to 1 / 0.02, still more preferably from 1/1 to 1 / 0.05, still more preferably from 1 / 0.8 to The ratio is 1 / 0.1, more preferably 1 / 0.4 to 1 / 0.1.

(Neutralizer)
Examples of the neutralizing agent used in the present invention include alkali metal hydroxides and organic bases. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Among these, the viewpoint of availability, low-temperature fixability of the toner, and storage stability under high temperature and high humidity. From the viewpoint of improving the properties and wax dispersibility, sodium hydroxide is preferable. Examples of the organic base include ammonia, trimethylamine, ethylamine, diethylamine, triethylamine, triethanolamine, and tributylamine. Among these, low-temperature fixability of toner, storage stability under high temperature and high humidity, and wax dispersibility From the viewpoint of improving the pH, a neutralizing agent having a pKa of 12 or less is preferable, and ammonia (pKa = 9.3) and triethylamine (pKa = 9.8) are preferable. Therefore, as the neutralizing agent, sodium hydroxide, ammonia, and triethylamine are preferable, and sodium hydroxide is more preferable from the viewpoint of improving low-temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility.

The degree of neutralization of the polyester resin with the neutralizing agent is preferably 20 mol% or more, more preferably 50 mol% or more, and still more preferably 60 mol% or more, from the viewpoint of improving the storage stability of the toner under high temperature and high humidity. And preferably 100 mol% or less, more preferably 95 mol% or less, still more preferably 90 mol% or less. In addition, the neutralization degree (mol%) of resin can be calculated | required by a following formula.
Degree of neutralization = {[mass of neutralizer (g) / equivalent of neutralizer] / [[acid value of resin (KOH mg / g) × mass of resin (g)] / (56 × 1000)]} × 100

In step 1, the order of adding the raw materials is not limited, but it is preferable that the neutralizing agent is mixed after the binder resin and the organic solvent are mixed.
At the time of mixing, it is preferable to stir with a commonly used mixing and stirring device such as an anchor blade or an external circulation stirring device.

  The temperature at the time of mixing in step 1 is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, further preferably 20 ° C. or higher, from the viewpoints of stabilizing the process temperature, shortening the process time, and reducing the viscosity of the solution. Yes, and preferably 50 ° C or lower, more preferably 40 ° C or lower, and still more preferably 35 ° C or lower. Stirring is preferably performed until no significant phase separation or insoluble matter is present. The stirring time depends on the stirring speed and temperature conditions, but is preferably 0.1 hours or more, more preferably 0.2 hours or more, still more preferably 0.3 hours or more, and preferably 5 hours or less, More preferably, it is 3 hours or less, More preferably, it is 1 hour or less.

  In Step 1 of the method of the present invention, optional components may be added as long as the effects of the present invention are not affected. For example, inorganic salts, organic solvents other than those described above, surfactants and the like can be mentioned.

[Step 2]
Step 2 is a step in which water is mixed with the mixture obtained in Step 1 to obtain a resin dispersion.

  The amount of water used in Step 2 is the mass ratio of water to organic solvent (water / organic solvent) from the viewpoint of improving low temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. Preferably it is 50 / 50-99 / 1, More preferably, it is 80 / 20-99 / 1, More preferably, it is 85 / 15-95 / 5.

  In addition, the amount of water used in step 2 is such that the mass ratio of water and binder resin (water / binder) from the viewpoint of improving low temperature fixability of toner, storage stability under high temperature and high humidity, and wax dispersibility. The resin is preferably 10/90 to 99/1, more preferably 15/85 to 97/3, and still more preferably 60/40 to 80/20.

At the time of mixing, it is preferable to stir with a commonly used mixing and stirring device such as an anchor blade or an external circulation stirring device.
When a mixing stirring device such as an anchor blade is used, the peripheral speed of stirring is preferably 20 m / min or more, more preferably 40 m / min or more, further preferably 60 m / min or more, from the viewpoint of dispersibility, and , Preferably 200 m / min or less, more preferably 150 m / min or less, and even more preferably 100 m / min or less.

  The temperature at the time of mixing in step 2 is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, more preferably 20 ° C. or higher, from the viewpoints of stabilizing the process temperature, shortening the process time, and reducing the viscosity of the solution. Yes, and preferably 50 ° C or lower, more preferably 40 ° C or lower, and still more preferably 35 ° C or lower.

  In step 2, the method of mixing water is not particularly limited, and the total amount may be added to the mixture obtained in step 1 at once, or it may be added in several portions or added dropwise intermittently. It may be added continuously through a pump or the like. The addition time depends on the stirring speed and temperature conditions from the viewpoint of dispersibility of the mixture obtained in step 1, but is preferably 0.5 hours or more, more preferably 1 hour or more, and preferably 5 hours. It is not more than time, more preferably not more than 3 hours.

[Step 3]
Step 3 is a step of obtaining an aqueous dispersion of the binder resin by removing the organic solvent from the resin dispersion obtained in Step 2.

  The method for removing the organic solvent in Step 3 is not particularly limited, and any method can be used. However, since it is dissolved in water, it is preferably distilled. In addition, the organic solvent may not be completely removed and may remain in the aqueous dispersion. In this case, the residual amount of the organic solvent is preferably 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.1% by mass or less, and still more preferably substantially 0% in the aqueous dispersion. %.

  When removing the organic solvent by distillation, it is preferable to raise the temperature to a temperature equal to or higher than the boiling point of the organic solvent to be used while stirring. Further, from the viewpoint of maintaining the dispersion stability of the binder resin, it is more preferable to evaporate by raising the temperature to a temperature equal to or higher than the boiling point of the organic solvent to be used at that pressure. Note that the temperature may be increased after the pressure is reduced, or the pressure may be decreased after the temperature is increased. From the viewpoint of maintaining the dispersion stability of the binder resin, it is preferable to distill off at a constant temperature and pressure.

[Step 4]
Step 4 is a step of mixing a surfactant with the aqueous dispersion obtained in Step 3.

(Surfactant)
The surfactant used in the present invention is an anionic surfactant having an oxyethylene group from the viewpoint of improving low-temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. By using a specific amount of an anionic surfactant having an oxyethylene group, the cohesiveness of the polyester emulsion is controlled, and the toner has excellent low-temperature fixability, storage stability under high temperature and high humidity, and excellent wax dispersibility Can be obtained.

Examples of the anionic surfactant having an oxyethylene group include polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene styrenated phenyl ether sulfate, and polyoxyethylene alkyl ether phosphate. And polyoxyethylene alkylphenyl ether phosphate. The carbon number of the alkyl group in these is preferably 6 or more, more preferably 10 or more, and preferably 18 or less, more preferably 14 or less. Further, the average number of moles added of the oxyethylene group is preferably 0 mol or more, more preferably more than 0 mol, more preferably 1 mol or more, still more preferably 1.5 mol or more, and preferably 10 mol or less. More preferably, it is 5 mol or less, More preferably, it is 3 mol or less. As a counter ion forming a salt with these anionic surfactants, inorganic ions such as potassium, sodium and ammonium, and organic amines such as monoethanolamine, diethanolamine and triethanolamine are preferable.
These surfactants can be used alone or in combination of two or more. Among these, polyoxyethylene alkyl ether sulfate is preferable, and sodium polyoxyethylene lauryl ether sulfate is preferable. As a commercial item of the anionic surfactant which has an oxyethylene group, "Emar E-27C" (Polyoxyethylene lauryl ether sodium sulfate, Kao Corporation make) can be mentioned, for example.

  As the surfactant used in Step 4, a surfactant other than the anionic surfactant having an oxyethylene group may be contained within a range not impairing the effects of the present invention. Examples of such surfactants include nonionic surfactants, anionic surfactants having no oxyethylene groups, and cationic surfactants.

Nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl aryl ethers such as polyoxyethylene lauryl ether, polyoxyethylene alkyl ethers, polyethylene glycol monolaurate , Polyoxyethylene fatty acid esters such as polyethylene glycol monostearate and polyethylene glycol monooleate, and oxyethylene / oxypropylene block copolymers. Among these, from the viewpoint of emulsion stability of the resin, polyoxyethylene Alkyl ethers are preferred.
Examples of the anionic surfactant having no oxyethylene group include sulfate-based, sulfonate-based, phosphate-based, and soap-based (for example, alkyl ether carboxylate) anionic surfactants. The thing which does not have an ethylene group is mentioned. Specific examples include sodium alkylbenzene sulfonate, sodium alkyl sulfate, sodium alkyl ether sulfate, and the like.
Examples of the cationic surfactant include alkyltrimethylammonium chloride and dialkyldimethylammonium chloride.

  The content of the anionic surfactant having an oxyethylene group in the surfactant used in Step 4 is from the viewpoint of improving the low temperature fixability of the toner, the storage stability under high temperature and high humidity, and the wax dispersibility. In the surfactant, it is preferably at least 80 mol%, more preferably at least 90 mol%, still more preferably substantially 100 mol%.

  The addition amount of the surfactant in Step 4 is 1% by mass or more based on 100 parts by mass of the binder resin from the viewpoint of improving the low temperature fixability of the toner, the storage stability under high temperature and high humidity, and the wax dispersibility. , Preferably 1.5% by mass or more, more preferably 2% by mass or more, and preferably 10% by mass or less, preferably 9% by mass or less, more preferably 7% by mass or less.

When the surfactant is added, it is preferable to stir with a commonly used mixing and stirring device such as an anchor blade or an external circulation stirring device.
When a mixing stirring device such as an anchor blade is used, the peripheral speed of stirring is preferably 20 m / min or more, more preferably 40 m / min or more, further preferably 60 m / min or more, from the viewpoint of dispersibility, and , Preferably 200 m / min or less, more preferably 150 m / min or less, and even more preferably 100 m / min or less.

  The temperature at the time of addition of the surfactant in step 4 is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, more preferably 20 ° C. or higher, from the viewpoint of dispersibility of the surfactant in water, and the like. Preferably it is 50 degrees C or less, More preferably, it is 40 degrees C or less, More preferably, it is 35 degrees C or less.

  The solid content concentration of the aqueous dispersion obtained through the production process of the aqueous dispersion including Step 1 to Step 4 is preferably 3 by appropriately adding water from the viewpoint of the stability of the dispersion and ease of handling. % By mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 20% by mass or less. Is done. In addition, solid content is the total amount of non-volatile components, such as resin and surfactant.

The volume median particle size (D ₅₀ ) of the resin particles contained in the aqueous dispersion obtained through the production process of the aqueous dispersion including Step 1 to Step 4 is preferably 70 nm or more, more preferably 80 nm or more, and still more preferably. Is 90 nm or more, more preferably 100 nm or more, and preferably 200 nm or less, more preferably 180 nm or less, still more preferably 150 nm or less, and further preferably 130 nm or less.

  From the viewpoint of improving low-temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility, it is preferable to have a step of adjusting the pH of the aqueous dispersion to 1 or more and 5 or less after Step 4.

[Aggregation process]
In the aggregation step, the resin particles in the aqueous dispersion of the binder resin for toner and the release agent particles in the aqueous dispersion containing the wax as the release agent are aggregated to obtain a dispersion of aggregated particles. It is preferable.

  In the aggregation process, it is preferable to add an aggregating agent in order to efficiently perform aggregation. As the flocculant, a quaternary salt cationic surfactant, an organic flocculant such as polyethyleneimine; and an inorganic flocculant such as inorganic metal salt and inorganic ammonium salt are used. From the viewpoint of improving low-temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility, inorganic flocculants are preferable, and inorganic metal salts are particularly preferable. Examples of the inorganic metal salt include sodium sulfate, sodium chloride, calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, and aluminum chloride. The valence of the central metal of the inorganic metal salt is preferably 2 or more from the viewpoint of improving low-temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. As the inorganic metal salt, magnesium chloride is preferred.

  When the flocculant is added, the addition amount is preferably 0 with respect to 100 parts by mass of the binder resin from the viewpoint of improving the low temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. 0.001 part by mass or more, more preferably 0.005 part by mass or more, further preferably 0.01 part by mass or more, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less, still more preferably 5 parts by mass. Part or less, more preferably 2 parts by weight or less.

The flocculant is preferably added after being dissolved in an aqueous medium, and it is preferable that the flocculant is sufficiently stirred at the time of addition of the flocculant and after completion of the addition.
In the flocculation step, the solid content concentration in the system is preferably 5% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably, in order to cause uniform aggregation. 30% by mass or less.
In the aggregating step, from the viewpoint of uniformly dispersing the aggregating agent and causing uniform agglomeration, it is preferable to add the aggregating agent at 20 ° C. or more and 40 ° C. or less. It is preferable to hold at 40 ° C. or higher and 70 ° C. or lower until the diameter is reached.

  In the aggregation step, aggregation may be performed after adding a release agent, a colorant, a charge control agent, a conductivity adjusting agent, a reinforcing filler such as a fibrous substance, and an additive such as an antioxidant. The additive can also be used as an aqueous dispersion.

(Release agent (wax))
In the present invention, the agglomerated particles obtained in the aggregating step contain a wax as a release agent.
Examples of waxes include plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, and jojoba oil; animal waxes such as beeswax; montan wax, ozokerite, ceresin, microcrystalline wax, and Fischer-Tropsch wax. Examples thereof include waxes such as mineral and petroleum waxes; polyolefin waxes, paraffin waxes and the like. Among these, ester wax is preferable.

  Moreover, you may use together mold release agents other than a wax. Examples of mold releasing agents other than wax include fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide; silicones and the like. You may use a mold release agent individually or in combination of 2 or more types.

  The melting point of the release agent is preferably 60 ° C. or higher, and preferably 140 ° C. or lower, more preferably from the viewpoint of improving low-temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. Is 100 ° C. or lower.

  The weight ratio of the release agent to the total amount of the binder resin [total amount of the release agent / binder resin] is from the viewpoint of improving the low temperature fixability of the toner, the storage stability under high temperature and high humidity, and the wax dispersibility. Preferably it is 0.1 / 100-10 / 100, More preferably, it is 0.5 / 100-8 / 100, More preferably, it is 1 / 100-7 / 100.

  The total wax content in the toner is preferably 1% by mass or more, more preferably 1.5% by mass, from the viewpoint of improving low-temperature fixability of the toner, storage stability under high temperature and high humidity, and wax dispersibility. Or more, more preferably 2% by mass or more, still more preferably 2.5% by mass or more, and preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 8% by mass or less, and still more. Preferably it is 5 mass% or less. The amount of wax added is determined so that the total wax content in the toner falls within the above range.

  As a method for adding and aggregating the release agent, the release agent may be added to the aqueous dispersion of the binder resin for aggregation, or the aqueous dispersion of the release agent prepared in advance in the aggregation process. The particles and the aqueous dispersion of the binder resin obtained through steps 1 to 4 may be mixed to produce agglomerated particles, or the binder resin and the release agent may be mixed in step 1 to obtain the present invention. Aggregated particles may be produced through an agglomeration step as an aqueous dispersion containing a binder resin and a release agent obtained through the steps 1 to 4.

(Coloring agent)
There is no restriction | limiting in particular as a coloring agent, A well-known coloring agent is mentioned, According to the objective, it can select suitably. Specifically, carbon black, inorganic composite oxide, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, Brilliantamine 6B, DuPont Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, etc. Various pigments: acridine, xanthene, azo, benzoquinone, azine, anthraquinone, indico, Indigo dyes, phthalocyanine, aniline black, polymethine, triphenylmethane dyes, diphenylmethane dyes, thiazine, and include various dyes of thiazole, and the like. These can be used alone or in combination of two or more.
From the viewpoint of improving the image quality, the addition amount of the colorant is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and preferably 20 parts by mass with respect to 100 parts by mass of the binder resin. Part or less, more preferably 10 parts by weight or less.

In addition, additives such as a colorant and a charge control agent may be premixed in the binder resin when preparing the resin particles, or a dispersion in which each additive is separately dispersed in a dispersion medium such as water. It may be prepared, mixed with an aqueous dispersion of a binder resin, and subjected to an aggregation step.
When the additive is previously mixed with the binder resin when preparing the resin particles, it is preferable to melt-knead the binder resin and the additive in advance.
For melt kneading, it is preferable to use an open roll type biaxial kneader. An open roll type biaxial kneader is a kneader in which two rolls are arranged close to each other in parallel, and a heating function or a cooling function can be imparted by passing a heat medium through each roll. Therefore, the open-roll type twin-screw kneader is an open-type part to be melt-kneaded, and is provided with a heating roll and a cooling roll, so that it occurs during melt-kneading unlike a normal twin-screw extruder. The kneading heat can be easily dissipated.
In addition, an aqueous dispersion of each additive can be obtained by mixing each additive, a surfactant, and water and dispersing the mixture with a disperser.

[Fusion (unification) process]
In the fusing (unifying) step, an aggregation stopper is added to the aqueous dispersion of the agglomerated particles obtained in the aggregating step as necessary, and then heated as necessary to fuse the agglomerated particles. 1) to obtain fused particles (unified particles).
The temperature in the system in the fusing (unification) process is the target toner particle size, particle size distribution, shape control and particle fusing properties, low temperature fixability of the toner, storage stability under high temperature and high humidity. From the viewpoint of improving the properties and wax dispersibility, the softening point of the binder resin is preferably −40 ° C. or higher, more preferably −35 ° C. or higher, still more preferably −30 ° C. or higher, and preferably It is + 40 ° C. or lower, more preferably + 20 ° C. or lower, and further preferably + 10 ° C. or lower. Specifically, it is preferably 70 ° C or higher, and preferably 100 ° C or lower, more preferably 90 ° C or lower. The stirring speed is preferably a speed at which the aggregated particles do not settle.
In addition, when using an aggregation terminator, it is preferable to use a surfactant as the aggregation terminator, and it is more preferable to use an anionic surfactant. As an anionic surfactant, the anionic surfactant which has the oxyethylene group used at the said process 4 can be used.

[Electrophotographic toner]
Electrofused toner (simply referred to as toner) is obtained by subjecting the fused particles (unified particles) obtained in the fusion (unification) step to a solid-liquid separation step such as filtration, a washing step, and a drying step as appropriate. Sometimes).
In the washing step, it is preferable to use an acid in order to remove metal ions on the surface of the toner in order to ensure sufficient charging characteristics and reliability as the toner. Moreover, it is preferable to completely remove the added surfactant by washing, and washing with an aqueous solution below the cloud point of the surfactant is preferred. The washing is preferably performed a plurality of times.
In the drying step, any method such as a vibration type fluidized drying method, a spray drying method, a freeze drying method, a flash jet method, or the like can be employed. The water content after drying of the toner is preferably adjusted to 1.5% by mass or less, more preferably 1.0% by mass or less, from the viewpoint of chargeability.

  In the electrophotographic toner obtained by the method of the present invention, the toner particles can be used as the toner as they are, but it is preferable to use a toner obtained by adding an external additive to the surface of the toner particles. Examples of the external additive include hydrophobic silica, titanium oxide fine particles, alumina fine particles, cerium oxide fine particles, inorganic fine particles such as carbon black, and polymer fine particles such as polycarbonate, polymethyl methacrylate, and silicone resin. Silica is preferred.

  When the surface treatment of toner particles is performed using an external additive, the amount of the external additive added is based on 100 parts by mass of the toner particles before the treatment with the external additive from the viewpoint of improving the storage stability of the toner. The amount is preferably 1 part by mass or more, and preferably 5 parts by mass or less, more preferably 3.5 parts by mass or less, and still more preferably 3 parts by mass or less.

The volume median particle size (D ₅₀ ) of the toner is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more, and further preferably 4 μm or more, from the viewpoint of improving image quality and productivity. And preferably it is 10 micrometers or less, More preferably, it is 8 micrometers or less, More preferably, it is 7 micrometers or less, More preferably, it is 6 micrometers or less.

The CV value of the toner is preferably 45% or less, more preferably 40% or less, still more preferably 35% or less, still more preferably 30% or less, and even more preferably 25%, from the viewpoint of improving image quality and productivity. It is as follows. The CV value can be calculated by the following formula.
CV value (%) = (standard deviation of particle size distribution / volume median particle size (D ₅₀ )) × 100

  The electrophotographic toner obtained by the method of the present invention can be used as a one-component developer or as a two-component developer mixed with a carrier.

<Measurement of resin properties>
(Softening point and glass transition temperature of polyester resin)
(1) Softening point Using a flow tester “CFT-500D” (manufactured by Shimadzu Corporation), a 1 g sample was heated at a heating rate of 6 ° C./min, and a load of 1.96 MPa was applied by a plunger. The nozzle was extruded from a nozzle having a diameter of 1 mm and a length of 1 mm. The amount of plunger drop of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was taken as the softening point.
(2) Glass transition temperature Using a differential scanning calorimeter “Pyris 6 DSC” (manufactured by PerkinElmer), the temperature was raised to 200 ° C., and the temperature of the sample cooled to 0 ° C. at a temperature lowering rate of 50 ° C./min was raised. It was measured at 10 ° C / min. When an endothermic peak is observed, the temperature of the peak is measured. When a step is observed without the peak being observed, a tangent indicating the maximum slope of the curve of the step and an extension of the baseline on the high temperature side of the step The temperature at the point of intersection was taken as the glass transition temperature.

(Resin acid value)
The acid value of the resin was measured based on the method of JIS K0070. However, only the measurement solvent was changed from a mixed solvent of ethanol and ether specified in JIS K0070 to a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

<Measurement of physical properties of dispersion>
(Volume-median particle size (D ₅₀ ) of resin particles, colorant fine particles, release agent fine particles, charge control agent fine particles and aggregated particles in each dispersion)
What diluted the dispersion liquid with ion-exchange water so that it might become 0.01 mass% of solid content using the dynamic light-scattering type | formula particle size measuring machine "ZETASIZER NANO ZS" (made by Malvern), and the following The volume-median particle size (D ₅₀ ) was measured under the conditions.
Measurement temperature: 25 ° C
Medium: Water Measurement cell: Glass Cuvette
Laser specifications: He-Ne, 4mW, 633nm
Detection optical system: NIBS, 173 ° C.
Number of measurements: 10 times Isothermal time: 5 minutes Analysis software: Zeta Sizer Software 6.2
Analysis method: General Purpose Mode (cumulant method)

(Measurement of solid content of resin dispersion and aqueous dispersion)
Using an infrared moisture meter “FD-230” (manufactured by Kett Scientific Laboratory), 5 g of the resin dispersion or aqueous dispersion was measured at a drying temperature of 150 ° C. and a measurement mode 96 (monitoring time 2.5 minutes / variation range 0). .05%), and the moisture content (mass%) of the resin dispersion or aqueous dispersion was measured. The solid content was calculated according to the following formula.
Solid content concentration (% by mass) = 100-M
M: moisture (mass%) of resin dispersion or aqueous dispersion = [(W−W0) / W] × 100
W: Sample mass before measurement (initial sample mass)
W0: Sample weight after measurement (absolute dry weight)

(Emulsion pH)
It measured at 20 degreeC using pH meter "HM-20P" (made by Toa DK Corporation).

(Melting point of release agent)
Using a differential scanning calorimeter “DSC 210” (manufactured by Seiko Denshi Kogyo Co., Ltd.), the sample was heated to 200 ° C. and cooled to 0 ° C. at a temperature decrease rate of 10 ° C./min. The temperature was raised in minutes, and the maximum peak temperature of heat of fusion was taken as the melting point.

(Volume-median particle size (D ₅₀ ) and CV value of toner particles)
Measuring machine: "Coulter Multisizer III" (Beckman Coulter, Inc.)
Aperture diameter: 50 μm
Analysis software: "Multisizer III version 3.51" (manufactured by Beckman Coulter)
Electrolyte: “Isoton II” (Beckman Coulter, Inc.)
Dispersion: “Emulgen 109P” (polyoxyethylene lauryl ether, manufactured by Kao Corporation, HLB: 13.6) 5% electrolyte dispersion condition: 10 mg of a measurement sample was added to 5 mL of the dispersion, and 1 with an ultrasonic disperser. The sample dispersion was prepared by dispersing for 25 minutes, then adding 25 mL of the electrolyte, and further dispersing for 1 minute with an ultrasonic disperser.
Measurement conditions: 100 mL of electrolyte and dispersion were added to a beaker, the dispersion was added so that the particle size of 30,000 particles could be measured in 20 seconds, and 30,000 particles were measured. The volume-median particle size (D ₅₀ ) was determined from the distribution.
The CV value (%) was calculated according to the following formula.
CV value (%) = (standard deviation of particle size distribution / volume median particle size (D ₅₀ )) × 100

(Critical aggregation concentration)
The critical flocculation concentration is the minimum molar concentration of the flocculating agent necessary for flocculating the aqueous dispersion of the binder resin, and was measured by the following method.
(1) 10 g of an aqueous dispersion of a binder resin was collected, and 7.5 g of an emulsion prepared to have a solid content of 10% by mass with ion-exchanged water was weighed into a 30 mL screw tube. The following steps were performed while stirring with a magnetic stirrer.
(2) Magnesium chloride was weighed in an amount of 0.5 equivalents with respect to the number of moles of carboxy groups of the binder resin constituting the emulsion.
(3) Ion exchange water is added to the measured magnesium chloride, and the magnesium ion concentration in the added solution is adjusted to 10 to 1300 mM, and the magnesium ion concentration is 10 mM to 200 mM in increments of 10 mM, from 200 mM to 1300 mM. Prepared an aqueous magnesium chloride solution in increments of 50 mM.
(4) A magnesium chloride aqueous solution was slowly added to the sample solution with a pipette, and the screw tube was capped.
(5) The screw tube was stirred with a magnetic stirrer for 30 minutes.
(6) The volume-median particle size (D ₅₀ ) was measured with a laser diffraction type particle size measuring instrument “LA-920” (manufactured by Horiba, Ltd.). Of the magnesium chloride concentrations at which the particle size was twice or more the particle size before the process, the lowest concentration was defined as the critical aggregation concentration (mM) of the emulsion.

<Toner evaluation>
(Minimum toner fixing temperature)
Toner was mounted on a copier “LaserJet 4200” (manufactured by Hewlett Packard), and the toner adhesion amount was adjusted to 0.7 mg / cm ² to obtain an unfixed image. Thereafter, the fixing machine of the copying machine “AR-505” (manufactured by Sharp Corporation) was adjusted to a total fixing pressure of 40 kgf and a fixing speed of 390 mm / sec. Using this fixing machine, the temperature of the fixing roll was set to 100 ° C. The fixing test of unfixed images was performed at each temperature while gradually increasing from 5 ° C. to 240 ° C. by 5 ° C. A cellophane adhesive tape “UNICEF Cellophane” (Mitsubishi Pencil Co., Ltd., width: 18 mm, JIS Z1522) was attached to the fixed image, passed through a fixing roller set at 30 ° C., and then the tape was peeled off. The optical reflection density before and after the tape was peeled was measured using a reflection densitometer “RD-915” (manufactured by Gretag Macbeth Co.), and the ratio between the two (after peeling / before sticking × 100) was initially 90%. The temperature of the fixing roller exceeding the temperature was set as the minimum fixing temperature. The lower the minimum fixing temperature, the better the low temperature fixing property.

(Storage stability of toner under high temperature and high humidity (HH))
4 g of toner was put in a 20 mL container (diameter: about 3 cm) and left for 24 hours in an environment of temperature 55 ° C. and humidity 85%. After standing, the degree of toner aggregation was visually observed, and storage stability was evaluated according to the following evaluation criteria.
A: No aggregation is observed even after 72 hours.
B: Aggregation is not observed after 60 hours, but slight aggregation is observed after 72 hours.
C: Aggregation is not observed after 48 hours, but aggregation is clearly observed after 60 hours.
D: Aggregation is not observed after 36 hours, but aggregation is clearly observed after 48 hours.
E: Aggregation is not observed after 24 hours, but aggregation is clearly observed after 36 hours.
F: Aggregation is clearly observed within 24 hours.

(Wax dispersibility)
The sample after melt-kneading of the toner was measured for 50 dispersed particle diameters of wax in a field of view with a magnification of 100,000 using a transmission electron microscope. The average value of the major axis and the minor axis was taken as the dispersed particle size. The average value of the measured dispersed particle diameter was defined as the average dispersed particle diameter, which was used as an index of wax dispersibility. It shows that it is excellent in the dispersibility of wax, so that the value of the average dispersion particle diameter of a wax dispersion particle is small.

<Manufacture of binder resin>
Production Examples 1-5
(Polyester resins A to E)
A fractionation tube with warm water of 98 ° C., a nitrogen introduction tube, equipped with a reflux condenser having an alcohol component, a carboxylic acid component, an esterification catalyst, and a pyrogallol compound as shown in Table 1 at the top and water of cold water at room temperature. Place in a 5 liter four-necked flask equipped with a dehydrating tube, stirrer and thermocouple, perform a polycondensation reaction at 160 ° C. for 2 hours in a nitrogen atmosphere, and then raise the temperature to 210 ° C. over 10 hours. Reaction was performed at 40 kPa until a desired softening point was reached, and polyester resins A to E were obtained.

<Preparation of dispersion other than aqueous dispersion of binder resin>
(Preparation of colorant dispersion)
Mixing 50 g of copper phthalocyanine “ECB-301” (manufactured by Dainichi Seika Kogyo Co., Ltd.), 5 g of nonionic surfactant “Emulgen 150” (polyoxyethylene lauryl ether, manufactured by Kao Corporation) and 200 g of ion-exchanged water Then, it was dispersed for 10 minutes using a homogenizer to obtain a colorant dispersion containing fine colorant particles. The volume median particle size (D ₅₀ ) of the fine colorant particles was 125 nm.

(Preparation of release agent dispersion)
50 g of ester wax “WEP8” (manufactured by Nippon Seiwa Co., Ltd., melting point: 78 ° C.), 5 g of cationic surfactant “Sanisol B-50” (alkylbenzyldimethylammonium chloride, manufactured by Kao Corporation) and ion-exchanged water 200 g was heated to 95 ° C., and the ester wax was dispersed using a homogenizer, followed by dispersion treatment using a pressure discharge type homogenizer to obtain a release agent dispersion containing release agent fine particles. The volume median particle size (D ₅₀ ) of the release agent fine particles was 400 nm.

(Preparation of charge control agent dispersion)
Charge control agent “Bontron E-84” (manufactured by Orient Chemical Co., Ltd.) 50 g, nonionic surfactant “Emulgen 150” (manufactured by Kao Corporation) 5 g and ion-exchanged water 200 g are mixed, and glass beads are mixed. Used and dispersed for 10 minutes using a sand grinder to obtain a charge control agent dispersion liquid containing charge control agent fine particles. The volume median particle size (D ₅₀ ) of the charge control agent fine particles was 500 nm.

Example 1
(Production of aqueous dispersion of polyester resin)
In a 3 L container equipped with a stirrer, reflux condenser, dropping funnel, thermometer and nitrogen introduction tube, 30 g of methyl ethyl ketone and 100 g of polyester resin A were charged and dissolved at 30 ° C. over 2 hours. 150 g of 5 mass% sodium hydroxide aqueous solution was added to the obtained solution, and it stirred for 30 minutes, and made the neutralization degree 80 mol% (process 1). While stirring at 250 rpm (circumferential speed 80 m / min), 270 g of ion-exchanged water was added over 70 minutes (step 2). Subsequently, after heating up to 60 degreeC over 30 minutes, methyl ethyl ketone was distilled off under reduced pressure (process 3). After cooling to 20 ° C., the solid content concentration of the dispersion was measured and adjusted with ion-exchanged water so as to be 20% by mass to obtain an aqueous dispersion. Thereafter, the aqueous dispersion was brought to 30 ° C. while stirring at 250 rpm (peripheral speed 80 m / min), and then an anionic surfactant “Emar E-27C” (sodium polyoxyethylene lauryl ether sulfate having an oxyethylene group, Kao Corporation, solid content 28% by mass) was added in an amount such that the amount added to the polyester resin was 5% by mass, and stirring was continued for 30 minutes (step 4). Thereafter, a 1N aqueous hydrochloric acid solution was added dropwise to adjust the pH to 3, and the mixture was stirred for 1 hour at 250 rpm (peripheral speed 80 m / min). Furthermore, the solid content concentration of the dispersion was measured, adjusted with ion-exchanged water so as to be 16% by mass, and then stirred for 1 hour to obtain an aqueous dispersion of a polyester resin.

(Manufacture of toner)
300 g of the polyester resin aqueous dispersion obtained above, 8 g of the colorant dispersion, 10 g of the release agent dispersion, 2 g of the charge control agent dispersion and 52 g of deionized water are placed in a 2 L container, and a chi-type stirrer is added. Then, 150 g of 0.2 mass% magnesium chloride aqueous solution was added dropwise at 30 ° C. over 30 minutes with stirring at 100 rpm (circumferential speed 31 m / min). Thereafter, the temperature was increased while stirring, and the temperature was maintained when the temperature reached 50 ° C. The average particle size reached 5.0 μm after 3 hours. Thereafter, 4.2 g of an anionic surfactant “Emar E-27C” (polyoxyethylene lauryl ether sodium sulfate, manufactured by Kao Corporation, solid content 28% by mass) as a coagulation terminator was diluted with 37 g of deionized water. The liquid was added. Next, the temperature was raised to 80 ° C., and after stirring for 1 hour from the time when the temperature reached 80 ° C., coalesced particles were formed, then gradually cooled to 20 ° C., and filtered through a wire mesh of 150 mesh (aperture 150 micrometers). Thereafter, suction filtration was performed, and toner particles were obtained through washing and drying processes.

(External addition process)
Hydrophobic silica “NAX-50” (manufactured by Nippon Aerosil Co., Ltd., number average particle size 40 nm) 1.0 part by mass, hydrophobic silica “R972” (Nippon Aerosil Co., Ltd.) with respect to 100 parts by mass of the toner particles. Manufactured, number average particle size 16 nm) 0.6 parts by mass, titanium oxide “JMT-150IB” (manufactured by Teika Co., Ltd., number average particle size 15 nm) 0.5 parts by mass, 10 L equipped with ST and A0 stirring blades A Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) was added and stirred at 3000 rpm for 2 minutes to obtain a toner. Table 2 shows the toner evaluation results.

Examples 2 and 3 and Comparative Example 2
In Example 1, except that Resin A was changed to Resins B, C, and E, respectively, and a 5 mass% sodium hydroxide aqueous solution was added in Step 1 so as to achieve the neutralization degree shown in Table 2. In the same manner as in Example 1, an aqueous dispersion of a polyester resin was obtained to obtain a toner. Table 2 shows the toner evaluation results.

Comparative Example 1
In Example 1, an attempt was made to produce an aqueous dispersion of a polyester resin in the same manner as in Example 1 except that the resin A was changed to the resin D. However, the aqueous dispersion of the polyester resin could be obtained without emulsification. could not.

Examples 4 and 5
In Example 1, a polyester resin aqueous dispersion was obtained in the same manner as in Example 1 except that a 5% by mass sodium hydroxide aqueous solution was added in Step 1 so that the degree of neutralization shown in Table 3 was obtained. Obtained. Table 3 shows the toner evaluation results.

Example 6
In Example 1, a polyester resin aqueous dispersion was obtained in the same manner as in Example 1 except that the pH was adjusted to 7 after Step 4 to obtain a toner. Table 3 shows the toner evaluation results.

Example 7
In Example 1, except that the addition amount of the anionic surfactant “Emar E-27C” having an oxyethylene group added in Step 4 was changed to an amount such that the addition amount with respect to the polyester resin was 1.5% by mass. Was obtained in the same manner as in Example 1 to obtain an aqueous dispersion of a polyester resin to obtain a toner. Table 3 shows the toner evaluation results.

Comparative Example 3
In Example 1, the anionic surfactant “Emar E-27C” having an oxyethylene group added in Step 4 is replaced with the anionic surfactant “Emar 0” having no oxyethylene group (sodium lauryl sulfate, Kao ( An aqueous dispersion of a polyester resin was obtained in the same manner as in Example 1 except that the product was changed to “manufactured”. A toner was prepared in the same manner as in Example 1 except that the obtained polyester resin aqueous dispersion was used. However, the toner did not aggregate and could not be obtained.

Comparative Example 4
In Example 1, it implemented except having changed the addition amount of the anionic surfactant "Emar E-27C" which has an oxyethylene group added at the process 4 into the quantity from which the addition amount with respect to a polyester resin becomes 12 mass%. A polyester resin aqueous dispersion was obtained in the same manner as in Example 1 to obtain a toner. Table 3 shows the toner evaluation results.

Comparative Example 5
In Example 1, except that the addition amount of the anionic surfactant “Emar E-27C” having an oxyethylene group added in Step 4 was changed to an amount such that the addition amount with respect to the polyester resin was 0.8 mass%. Was obtained in the same manner as in Example 1 to obtain an aqueous dispersion of a polyester resin to obtain a toner. Table 3 shows the toner evaluation results.

  From the above results, it can be seen that according to the method of the present invention, an electrophotographic toner excellent in low-temperature fixability, storage stability under high temperature and high humidity, and wax dispersibility can be obtained.

  The toner for electrophotography obtained by the method of the present invention is excellent in low temperature fixability, storage stability under high temperature and high humidity, and wax dispersibility. Therefore, it is used for electrophotography, electrostatic recording method, electrostatic printing method and the like. It can be suitably used as an electrophotographic toner.

Claims (4)

A method for producing an electrophotographic toner comprising particles obtained by fusing agglomerated particles obtained by aggregating an aqueous dispersion that is a mixture of an aqueous dispersion of a binder resin for a toner and a surfactant,
The agglomerated particles contain a wax as a release agent;
The binder resin contains a polyester resin that is a polycondensate of an alcohol component containing an aliphatic diol having 2 to 4 carbon atoms and a carboxylic acid component, and the acid value of the polyester resin is 5 mgKOH / g or more and 10 mgKOH / g or less,
The aqueous dispersion is obtained through the following steps 1, 2, 3 and 4,
Production of an electrophotographic toner, wherein the surfactant is an anionic surfactant having an oxyethylene group, and the amount of the surfactant added to the polyester resin in Step 4 is 1% by mass or more and 10% by mass or less. Method.
Step 1: A step of mixing at least a binder resin, an organic solvent and a neutralizing agent to obtain a mixture.
Step 2: A step of mixing the mixture obtained in Step 1 with water to obtain a resin dispersion.
Step 3: A step of obtaining an aqueous dispersion of the binder resin by removing the organic solvent from the resin dispersion obtained in Step 2.
Step 4: A step of mixing a surfactant with the aqueous dispersion obtained in Step 3.   The method for producing an electrophotographic toner according to claim 1, wherein the anionic surfactant having an oxyethylene group is polyoxyethylene alkyl ether sulfate. The method for producing an electrophotographic toner according to claim 1, wherein the volume-median particle size (D ₅₀ ) of the resin particles contained in the aqueous dispersion is 90 nm or more and 150 nm or less.   The method for producing an electrophotographic toner according to claim 1, wherein the aqueous dispersion after step 4 has a pH of 1 or more and 5 or less.