JP5054351B2 - Method for producing resin emulsion - Google Patents

Description

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

As a method for producing a chemical toner, a polymerization method and an emulsion dispersion method are known. Among these methods, a method for producing a toner by an emulsification dispersion method is a method in which, for example, a mixture of a binder resin and a colorant is mixed with an aqueous medium and emulsified to obtain toner particles. In this method, for example, when using polyester as a binder resin and preparing a polyester emulsion dispersion, a phase inversion emulsification method using an organic solvent or a forced emulsification method under high pressure / high temperature conditions is generally used. Furthermore, an improvement in the dispersibility of the pigment has been desired.
As such a technique, for example, an aqueous dispersion obtained by mixing a dispersion liquid (I) in an organic solvent (C) containing a resin (A) and a pigment (B) and an aqueous medium containing a dispersant (D). In a method for producing resin composition particles by granulating a body, (I) is a mixer having a function of rotating and revolving (A), (B), (C) and optionally a pigment dispersant (E). Disclosed is a method for producing resin composition particles, which is an adjustment liquid having a solid content concentration of 20 to 70%, which is obtained by diluting a mixed dispersion having a solid content concentration of 50 to 98% by weight, if necessary, with an organic solvent. (See Patent Document 1).

Further, a toner raw material containing at least a polyester resin is heated and melted to produce a melt of the toner raw material, and then the melt is emulsified in an aqueous medium to form resin fine particles. There has been disclosed a method for producing a toner for developing an electrostatic charge image, in which resin fine particles are aggregated and further fused to produce an aggregate of the resin fine particles (see Patent Document 2).
However, none of the techniques of Patent Document 1 and Patent Document 2 described above are sufficient in the dispersibility of the resin and the pigment, and the durability of the obtained toner is insufficient.

Japanese Patent Laid-Open No. 2002-249591 JP 2002-351140 A

  The present invention relates to a resin emulsion having good dispersibility and containing small-sized and uniform emulsion particles, a production method thereof, an electrophotographic toner excellent in image performance and durability obtained from the resin emulsion, and It relates to a manufacturing method.

The present invention
(1) A resin emulsion containing a binder resin containing a polyester and a colorant, wherein the volume median particle size (D ₅₀ ) of the emulsion particles in the resin emulsion is 0.5 μm or less, and A resin emulsion for toner having a coefficient of variation of 30 or less in the volume-based particle size distribution,
(2) (1) a step of dispersing a raw material containing a binder resin containing a polyester and a colorant in a basic aqueous medium, (2) a step of stirring and neutralizing the obtained dispersion, and (3) A method for producing a resin emulsion comprising a step of adding an aqueous solution to a neutralized dispersion and emulsifying in an aqueous medium, wherein at least the stirring in the step (2) is rotated about a revolution axis. A method for producing a resin emulsion for toner, wherein two or more shafts are connected, and a stirring blade provided on each rotation shaft performs a planetary motion,
(3) (a) A process for obtaining a resin emulsion by the production method described in (2) above, and (b) a process of aggregating and coalescing the emulsion particles in the obtained resin emulsion for electrophotography A toner production method, and (4) an electrophotographic toner obtained by the production method according to (3) above,
About.

  According to the present invention, it is possible to obtain a resin emulsion having good dispersibility, a small particle size and uniform emulsion particles, and an electrophotographic toner excellent in image performance and durability obtained from the resin emulsion. it can.

Resin emulsion for toner and method for producing the same The resin emulsion for toner of the present invention is a resin emulsion containing a binder resin containing polyester and a colorant, and the volume of emulsion particles in the resin emulsion is as follows. The unit particle size (D ₅₀ ) is 0.5 μm or less, and the coefficient of variation in the volume-based particle size distribution is 30 or less. That is, since the resin emulsion for toners of the present invention has a small particle size and a sharp particle size distribution, when used for the production of a toner obtained by agglomerating and coalescing emulsified particles, uniform agglomeration occurs. The resulting toner has high image density and high durability.

In the present invention, the volume median particle size (D ₅₀ ) of the emulsified particles in the resin emulsion is 0.5 μm or less from the viewpoint of obtaining a toner having a high image density and high durability, but is 0.4 μm or less. Preferably, it is 0.3 μm or less, more preferably 0.2 μm or less. In the present specification, the volume-median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size. The volume median particle size (D ₅₀ ) of the emulsified particles can be obtained by a laser diffraction particle size measurement method as described later. The coefficient of variation in the volume-based particle size distribution of the resin particles in the resin emulsion is 30 or less from the viewpoint of obtaining a toner having a high image density and high durability, but is preferably 28 or less, and preferably 27 or less. More preferably. The variation coefficient of the particle size distribution can be calculated according to the following formula from the particle size distribution obtained in the measurement of the particle size based on the volume.
Coefficient of variation = (standard deviation of particle size distribution / volume average particle size (D ₄ )) × 100
In the present invention, the volume average particle diameter (D ₄ ) means an average particle diameter calculated by a volume fraction.

  The resin emulsion for toner of the present invention comprises (1) a step of dispersing a raw material containing a binder resin containing a polyester and a colorant in a basic aqueous medium, and (2) stirring the obtained dispersion. And (3) a method for producing a resin emulsion comprising the steps of: (3) adding an aqueous liquid to the neutralized dispersion and emulsifying in an aqueous medium, at least in the step (2) Stirring is obtained by using a mixer in which two or more rotation shafts are connected to the revolution shaft, and a stirring blade provided on each rotation shaft performs planetary motion. Hereinafter, each step will be described.

[Step (1)]
This step is a step of dispersing a raw material containing a binder resin containing a polyester and a colorant in a basic aqueous medium.
The binder resin contains polyester, and well-known resins used for toner, for example, styrene-acrylic copolymer, epoxy, polycarbonate, polyurethane and the like can be used together with polyester. Among these, from the viewpoints of colorant dispersibility, fixability, and durability, styrene-acrylic copolymers are preferable in addition to polyester, and those having polyester as a main component are more preferable. The content of the polyester in the binder resin is preferably 60% by weight or more, more preferably 70% by weight or more, and still more preferably 80% by weight or more. In the present invention, the binder resin may be used in combination with one of the above-mentioned other resins together with polyester, but may be used in combination of two or more.

  The polyester may be either crystalline polyester or amorphous polyester, but amorphous polyester is preferable from the viewpoint of durability, chargeability and storage stability. The degree of crystallization of polyester can be represented by the crystallinity index defined by the ratio of the softening point to the highest endothermic peak temperature by the differential scanning calorimeter (softening point / highest endothermic peak temperature). When the ratio exceeds 1.5, the resin is amorphous. When the ratio is less than 0.6, the crystallinity is low and there are many amorphous portions. Therefore, as the crystalline polyester in the present invention, those having a crystallinity index of 0.6 to 1.5 are preferably used, and from the viewpoint of low-temperature fixability, 0.8 to 1.3 is more preferable. Preferably it is 0.9-1.1.

  The degree of crystallization 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. Here, the highest endothermic peak temperature refers to the temperature of the peak on the highest temperature side among the observed endothermic peaks. If the maximum endothermic peak temperature is within 20 ° C. from the softening point, this peak temperature is taken as the melting point, and if the difference from the softening point exceeds 20 ° C., this peak is taken as the peak due to glass transition. A method for measuring the softening point that defines the crystallinity index and the maximum endothermic peak temperature will be described later.

The raw material monomer of the polyester is not particularly limited, and a known alcohol component and a known carboxylic acid component such as carboxylic acid, carboxylic acid anhydride, or carboxylic acid ester are used.
Examples of the alcohol component include alkylenes of bisphenol A such as polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane (carbon number of 2 to 3). ) Oxide (average addition mole number 1-16) adduct, ethylene glycol, propylene glycol, glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol A, sorbitol, or their alkylene (2-4 carbon atoms) oxide (average) Addition mole number 1-16) Additions etc. are mentioned.
This alcohol component may be used individually by 1 type, and may be used in combination of 2 or more type.

The carboxylic acid component includes dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid, adipic acid and succinic acid, alkyl groups having 1 to 20 carbon atoms such as dodecenyl succinic acid and octenyl succinic acid, or carbon. Trivalent or higher polyvalent carboxylic acids such as succinic acid, trimellitic acid and pyromellitic acid substituted with alkenyl groups of 2 to 20, anhydrides of these acids and alkyls of these acids (1 to 3 carbon atoms) ) Esters and the like.
This carboxylic acid component may be used individually by 1 type, and may be used in combination of 2 or more type.

The polyester can be produced, for example, by subjecting an alcohol component and a carboxylic acid component to condensation polymerization at a temperature of about 180 to 250 ° C. in an inert gas atmosphere using an esterification catalyst as necessary.
As the esterification catalyst, an esterification catalyst such as a tin compound such as dibutyltin oxide or tin dioctylate or a titanium compound such as titanium diisopropylate bistriethanolamate can be used. The amount of the esterification catalyst used is preferably 0.01 to 1 part by weight, more preferably 0.1 to 0.6 part by weight, based on 100 parts by weight of the total amount of the alcohol component and the carboxylic acid component.

From the viewpoint of storage stability of the toner, the softening point of the polyester is preferably 70 to 165 ° C, and the glass transition point is preferably 50 to 85 ° C. The acid value is preferably 6 to 35 mgKOH / g, more preferably 10 to 35 mgKOH / g, and still more preferably 15 to 35 mgKOH / g, from the viewpoint of manufacturability during emulsification. The desired softening point and acid value can be obtained by adjusting the condensation polymerization temperature and reaction time.
From the viewpoint of the durability of the toner, the number average molecular weight of the polyester is preferably 1,000 to 10,000, and more preferably 2,000 to 8,000.

When the binder resin contains a plurality of resins, the softening point, glass transition point, acid value and number average molecular weight of the binder resin are the softening point and glass transition point as a mixture of the binder resins. , Acid value and number average molecular weight, and each value is preferably the same value as the polyester.
Further, the binder resin for toner of the present invention can contain two kinds of polyesters having different softening points from the viewpoint of fixability and durability, and the softening point of one polyester (I) is 70 to 115 ° C. The softening point of the other polyester (b) is preferably 115 ° C. or higher and 165 ° C. or lower. The weight ratio (I / B) between the polyester (A) and the polyester (B) is preferably 10/90 to 90/10, more preferably 50/50 to 90/10.

In addition, from the viewpoint of dispersing the resin particles quickly and uniformly, resin particles having a particle size that allows passage of 95% by weight or more, and 98% by weight or more of JIS Z 98801 sieve having an opening diameter of 5.6 mm are used as the binder resin. It is preferable. By using resin particles having such a particle size, they can be dispersed uniformly, and in the next neutralization step, uniform neutralization is possible, and homogeneous emulsified particles can be produced.
Examples of the alcohol component of the amorphous polyester include alkylenes of bisphenol A such as polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane ( It is preferable that an alkylene oxide adduct of bisphenol A represented by the above formula (I), such as an adduct having 2 to 3 carbon atoms and an oxide (average added mole number of 1 to 16), is preferably contained.

The amorphous polyester has at least one of a softening point of 70 to 165 ° C, a glass transition point of 50 to 75 ° C, an acid value of 1 to 40 mgKOH / g, and a hydroxyl value of 3 to 60 mgKOH / g. Those are preferably used.
The number average molecular weight of the amorphous polyester is preferably 1,000 to 100,000, more preferably 1,000 to 50,000, and still more preferably 1,000 to 12,000 from the viewpoints of durability and fixability. .
The amorphous polyester is contained in the binder resin in a proportion of preferably 60% by weight or more, more preferably 70% by weight or more from the viewpoint of toner durability and chargeability.

When a crystalline polyester is used, from the viewpoint of promoting crystallinity, the alcohol component includes ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentane. Aliphatic diols such as diol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, neopentylglycol, 1,4-butenediol, and the carboxylic acid component include maleic acid and fumaric acid. It preferably contains an aliphatic dicarboxylic acid such as acid, succinic acid, adipic acid or terephthalic acid.
From the viewpoint of low-temperature fixability, when a crystalline polyester is used, the number average molecular weight of the crystalline polyester is preferably 2,000 to 100,000, more preferably 2,000 to 20,000, and 2,000 to 10 2,000 is more preferable, and 2,000 to 8,000 is more preferable.

  The basic aqueous medium used in the step (1) refers to an aqueous medium containing a basic compound. As a basic compound, any of an inorganic basic compound and an organic basic compound may be sufficient. Examples of the inorganic basic compound include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, weak acid salts such as carbonates and acetates thereof, partially neutralized salts, and ammonia. . Examples of the organic basic compound include alkylamines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine and triethylamine, alkanolamines such as diethanolamine, and fatty acid salts such as sodium succinate and sodium stearate. These basic compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

  On the other hand, the aqueous medium has water as a main component, and from the viewpoint of environmental conservation, the water content is preferably 80% by weight or more, more preferably 90% by weight or more, and 100% by weight in the aqueous medium. Further preferred. In the present invention, it is preferable to disperse the binder resin using only water without substantially using an organic solvent. When components other than water are used, organic solvents that dissolve in water such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran are listed. Among these, alcohol-based organic solvents such as methanol, ethanol, isopropanol, butanol and the like, which are organic solvents that do not dissolve the resin, are preferable from the viewpoint of preventing mixing into the toner.

The content of the basic compound in the basic aqueous medium depends on the type of the basic compound to be used, but is usually 1 to 30% by weight, preferably 3 to 20% from the viewpoint of suppressing hydrolysis of the binder resin. %, More preferably 5 to 10% by weight.
In addition, the amount of the basic aqueous medium used is preferably 5 to 100 parts by weight with respect to 100 parts by weight of the binder resin from the viewpoint that a resin emulsion having uniform particles can be effectively prepared. Part by weight is more preferable, 20 to 80 parts by weight is further preferable, and 25 to 70 parts by weight is further preferable.

  In the present invention, a surfactant can be added during the dispersion treatment. The addition amount is preferably 5% by weight or less, more preferably 0.2% with respect to the resin for the purpose of suppressing foaming in the dispersion step and improving the emulsion stability of the finally obtained resin emulsion. -5 wt%, more preferably 0.5-4 wt%, more preferably 1-3 wt%. Examples of the surfactant include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium octadecyl sulfate, sodium oleate, sodium laurate, and potassium stearate; laurylamine acetate, stearylamine acetate, lauryltrimethylammonium chloride, and the like. Cationic surfactants such as: Amphoteric surfactants such as lauryl dimethylamine oxide; Nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, sorbitan monostearate, and polyoxyethylene alkyl amine It is done. Among these, anionic surfactants and nonionic surfactants are preferable from the viewpoint of emulsion stability and the like. These surfactants may be used individually by 1 type, and may be used in combination of 2 or more type.

In the step (1), a colorant is added to the binder resin, and additives such as a release agent and a charge control agent are added as necessary, and the mixture is dispersed.
The colorant is not particularly limited, and any known colorant can be used and can be appropriately selected. 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, thioi Zico system, phthalocyanine, aniline black, can be used alone or in combination of two or more kinds of various dyes of thiazole, and the like.
The use ratio of the binder resin and the colorant is preferably 70:30 to 97: 3, and more preferably 80:20 to 97: 3, in terms of weight ratio, from the viewpoints of toner chargeability, durability, print density, and the like. .

Specific examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point by heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide ; Plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax・ Petroleum-based wax. These mold release agents may be used individually by 1 type, and may be used in combination of 2 or more type.
The content of the release agent is usually about 1 to 20 parts by weight, preferably 2 to 15 parts by weight with respect to 100 parts by weight of the binder resin in consideration of the addition effect and the adverse effect on the chargeability.

Examples of charge control agents include benzoic acid metal salts, salicylic acid metal salts, alkyl salicylic acid metal salts, catechol metal salts, metal-containing bisazo dyes, tetraphenylborate derivatives, quaternary ammonium salts, alkylpyridinium salts, and the like. Can be mentioned. These may be used individually by 1 type and may be used in combination of 2 or more type.
The content of the charge control agent is usually 10 parts by weight or less, preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

In step (1), from the viewpoint of uniformly dispersing a mixture of resin particles, a colorant, and various additives used as necessary, a dispersion treatment is performed at a temperature below the glass transition point of the resin particles. Is preferred. By fusing the resin particles at a temperature not higher than the glass transition point of the resin particles, preferably at a temperature not higher than 10 ° C. below the glass transition point (hereinafter referred to as “glass transition point−10 ° C.”), the resin particles can be fused. It is possible to suppress and prepare a uniform resin dispersion. When a mixed resin is used, the glass transition point of the mixed resin mixed and melted at the mixing ratio is defined as the glass transition point of the binder resin. Moreover, when using a masterbatch, it is set as the glass transition point of the mixed resin including the resin used for it.
Specifically, in a basic aqueous medium containing a surfactant, resin particles such as polyester are stirred together with a colorant and the like at a temperature below the glass transition point of the resin particles, for example, about 10 to 50 ° C. A uniform resin dispersion can be prepared by an ordinary method such as dispersion treatment.

[Step (2)]
This step is a step of substantially neutralizing the resin dispersion obtained in the step (1) by stirring. From the viewpoint of uniformly neutralizing the resin, the stirring time is preferably 30 minutes or longer, more preferably 1 hour or longer.
Neutralization is preferably performed at a temperature not lower than the glass transition point and not higher than the softening point of the binder resin. By carrying out at the temperature within the above range, neutralization is sufficiently carried out, generation of large emulsified particles is suppressed in the emulsification treatment in the next step, and no special apparatus is required for heating. In this respect, the neutralization temperature is preferably a temperature of the glass transition point of the resin + 10 ° C. or more, and is a temperature of a softening point −5 ° C. (hereinafter referred to as “softening point −5 ° C.”) or less. It is preferable.

The degree of neutralization in this neutralization step may be such that hydrophilicity necessary for producing emulsified particles in the next step can be imparted to the resin, and it is not always necessary to neutralize 100%. For example, when a highly hydrophilic resin having many polar groups is used, the degree of neutralization may be low. Conversely, when a resin having low hydrophilicity is used, it is preferable to increase the degree of neutralization. In the present invention, the degree of neutralization is preferably 50% or more, more preferably 60 to 100%, and more preferably 70 to 100% from the viewpoint of obtaining emulsifying properties, small particles and uniform particles. More preferably. The degree of neutralization can generally be represented by the ratio of the number of moles of acid groups before and after neutralization (number of moles of acid groups after neutralization / number of moles of acid groups before neutralization).
Specifically, the resin dispersion dispersed in the step (1) is preferably softened while stirring, preferably at a temperature not lower than the glass transition point and not higher than the softening point of the resin, for example, a glass transition point of about 60 to 65 ° C. When a polyester having a carboxyl group with a point of about 110 to 120 ° C. is used, the temperature is raised to a temperature of about 90 to 100 ° C. and held at that temperature for an appropriate time until a predetermined degree of neutralization is reached. To neutralize.

In step (2), from the viewpoint of the dispersibility of the colorant and the resin and the durability of the toner, two or more rotation shafts are connected to the revolving shaft for stirring, and the stirring blades provided on the respective rotation shafts move in planetary motion. It is preferable to use a mixer (hereinafter sometimes referred to as a planetary mixer), a Kai-type stirrer, a kneader-type mixer or the like, and more preferably a planetary mixer.
That is, in the present invention, since the mixing (kneading) is performed in a state where the solid content concentration composed of the colorant and the resin is high, the viscosity of the mixed (kneading) product varies in a wide range depending on the mixing (kneading) state. . In particular, since the step (2) is in a high-viscosity state, stirring may be insufficient or non-uniform, and as a result, the resin and the colorant may not be sufficiently dispersed and emulsified. From the above points, it is preferable to use the above-mentioned mixer as a mixer, and a planetary mixer is preferable from the viewpoint of being able to deal with a wide range from low viscosity to high viscosity.

  The planetary mixer uses a biaxial stirring blade that rotates and revolves respectively to stir and mix (knead) the mixture in the stirring tank, and has a structure that can reduce dead space in the stirring tank. And uniform mixing (kneading) can be obtained. Moreover, high load can be applied by making the shape of a blade | wing thick. Furthermore, mixing (kneading) is possible in a wide region from a high load region to a low load region, and all states from high viscosity to low viscosity at the time of mixing can be performed in the same stirring tank.

The planetary mixer used in the present invention is a mixer in which two or more rotation shafts are connected to a revolution shaft, and a stirring blade provided on each rotation shaft performs planetary motion. The above rotating shafts are connected to the revolving shafts, and each rotating shaft performs planetary motion to perform uniform mixing (kneading) in a state where there is no dead space in the tank.
An example of a planetary mixer that can be used in the present invention is shown in FIG. 1, and a partially enlarged view including the stirring blades is shown in FIG.
In the figure, reference numeral 1 denotes a stirring tank, and the stirring tank 1 is composed of an upper member 2 and a lower member 3. Inside the upper member 2, stirring blades 4 and 5, for example, frame-shaped blades are attached to one rotor 6. Is retained. When the rotor 6 rotates (revolves), the stirring blades 4 and 5 rotate (rotate) in the same direction. And the so-called planetary motion (planetary motion) in which the two agitating blades 4 and 5 rotate together with the revolution motion of the rotor 6 is performed.

  In the planetary mixer, a strong shearing force acts between the stirring blades 4 and 5 and between them and the inner surface of the stirring tank 1 due to such planetary motion of the stirring blades 4 and 5, and high-level stirring is performed. , Kneading and dispersing action can be obtained. When the dispersion is mixed while being heated to a predetermined temperature, the resin becomes viscous and is mixed with the colorant, so that a large load is applied to the rotation of the stirring blades 4 and 5. At this time, a large shearing force is applied to the material between the stirring blades 4 and 5 and between the stirring blades 4 and 5 and the stirring tank 1, and the resin and the colorant are sufficiently dispersed and mixed. Further, the stirring blades provided on the rotation shaft perform planetary motion, so that uniform and efficient mixing is possible. In particular, by using a kneader such as a planetary mixer, efficient mixing (kneading) can be performed by mild stirring without strong stirring, and a resin, a colorant, an aqueous medium, or a dispersion Particles and the like are almost thoroughly mixed.

  In the present invention, it is preferable to use one having a shape twisted in a direction opposite to the rotation direction of rotation as at least one of the stirring blades provided on the rotation shaft. Here, the “twisted shape” means that a flat blade as shown in FIG. 2 is twisted in the direction opposite to the direction of rotation so that a downward pressing force can be applied to the mixture. The shape is not particularly limited as long as it is an added shape, but specifically, it is twisted with respect to a plane parallel to the rotation axis including the flat blade so as to form a certain angle with the plane in a direction opposite to the rotation direction. The one with the shape. FIG. 3 is an enlarged view showing an example of a stirring blade having a shape twisted in a direction opposite to the rotation direction of such rotation. With such a structure, a movement for pressing the mixture downward is added, and the mixture is convected up and down, so that more uniform mixing (kneading) is possible.

  The degree of twisting is not particularly limited and can be appropriately adjusted according to the desired degree of stirring, but is preferably adjusted so as to enable more uniform mixing (kneading). Specifically, for example, when the stirring blade is a frame-type blade, from the viewpoint of improving the mixing property, a twist angle formed by a plane parallel to the rotation axis including a flat blade that is not twisted and the tip of the twisted blade. Is, for example, preferably 10 to 90 °, more preferably 30 to 80 °. There is no restriction | limiting in particular about the shape and magnitude | size of the stirring blade provided in the said rotating shaft, It can select suitably from what is normally used so that required stirring may be obtained.

The stirring peripheral speed of the stirring blade provided on the rotating shaft of the mixer is the viewpoint of the performance of the toner obtained by the production method of the present invention for the stirring blade provided on the rotating shaft. Therefore, it is preferably 0.4 to 5 m / sec, and more preferably 0.4 to 4 m / sec. The peripheral speeds of the two or more stirring blades may be the same or different.
The chi-type stirrer that can be used in the present invention is not particularly limited, and any commonly used one can be used. The stirring peripheral speed is preferably 0.5 m / sec or more, and more preferably 0.5 to 3 m / sec, from the viewpoint of dispersibility of the resin and the colorant.

In the step (3), the particles (dispersed particles) in the dispersion obtained in each of the steps (1) and (2) have good dispersibility by using the mixer as described above. The obtained emulsified particles have a small particle size and a uniform particle size distribution with little fluctuation, and also have excellent emulsification stability and high aggregation properties. Further, the toner obtained using such emulsified particles has good dispersibility of the colorant and can realize a high image density. Further, since uniform agglomeration is possible, voids in the toner are reduced and the durability is excellent. Furthermore, such emulsified particles enable rapid production of toner with quick start of aggregation.
Stirring using the mixer can sufficiently achieve the effects of the present invention as long as it is carried out in step (2). However, the above viewpoints and prevention of raw material loss and contamination associated with the transfer of raw materials during production can be obtained. From the viewpoint of the above, it is more preferable to carry out the step (1) and / or the step (3) described later together with the step (2), and mixing (kneading) all the steps from the step (1) to the step (3). More preferably, it is carried out with the above mixer.

[Step (3)]
This step is a step of adding an aqueous liquid to the dispersion neutralized in the step (2) and emulsifying it in an aqueous medium, and this step is a step from the viewpoint of preparing a fine resin emulsion. Maintaining the resin dispersion neutralized in (2) at a temperature not lower than the glass transition point and not higher than the softening point of the resin, adding an aqueous liquid thereto while stirring and emulsifying in an aqueous medium. Is preferred.
By carrying out the emulsification at a temperature within the above range, the emulsification is carried out smoothly and no special apparatus is required for heating. From this, the temperature at the time of emulsification is preferably a temperature of glass transition point + 10 ° C. or higher, and a temperature of softening point −5 ° C. or lower is preferable.

In this emulsification step, the resin content in the dispersion is preferably about 50 to 90% by weight, more preferably 50 to 80% by weight, from the viewpoint of easy phase inversion immediately before the start of emulsification. Here, “immediately before the start of emulsification” refers to a point in time when the viscosity of the system becomes the highest in all the steps. Therefore, by attaching a torque meter or the like to the stirrer, the point in time can be easily known.
The emulsification start time can be arbitrarily adjusted depending on the acid value and the degree of neutralization of the resin used. For example, when the acid value of the resin is increased or the degree of neutralization is increased, the hydrophilicity of the resin is increased, and emulsification can be started by contacting with a small amount of an aqueous medium.

  The aqueous liquid used for emulsification is mainly composed of water, and from the viewpoint of environmental conservation, the water content is preferably 80% by weight or more, more preferably 90% by weight or more in the aqueous medium, 100 % By weight is more preferred, specifically deionized water. In the present invention, it is preferable to disperse the binder resin using only water without substantially using an organic solvent. When components other than water are used, organic solvents that dissolve in water such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran are listed. The addition rate of the aqueous liquid is preferably 0.5 to 50 g / min, more preferably 0.5 to 30 g / min, and further preferably 1 to 20 g per 100 g of resin from the viewpoint that emulsification can be effectively carried out. / Min. In general, the addition rate may be maintained until the O / W type emulsion is substantially formed, and the addition rate of the aqueous liquid after the formation of the O / W type emulsion is not particularly limited.

The solid content concentration of the resin emulsion thus obtained is preferably 7 to 50% by weight from the viewpoint of the stability of the emulsion and the handleability of the resin emulsion in the subsequent aggregation step. -45 wt% is more preferable, and 10-40 wt% is more preferable.
Further, the volume median particle size (D ₅₀ ) of the emulsified particles after forming the O / W type emulsion is preferably 0.02 to 2 μm, more preferably in order to perform uniform aggregation in the aggregation step. Is 0.05-1 μm, more preferably 0.05-0.5 μm.

The resin emulsion for toner of the present invention is a resin emulsion containing a binder resin containing polyester and a colorant, and the volume median particle size (D ₅₀ ) of the emulsion particles in the resin emulsion is 0. 0.5 μm or less, and the coefficient of variation in the volume-based particle size distribution is 30 or less.
The binder resin and the colorant containing polyester are as described above. In the present invention, the volume median particle size (D ₅₀ ) of the emulsified particles in the resin emulsion is 0.5 μm or less from the viewpoint of obtaining a toner having high image density and high durability, but is 0.4 μm or less. Is preferably 0.3 μm or less, and more preferably 0.2 μm or less.

The coefficient of variation in the volume-based particle size distribution of the resin particles in the resin emulsion is 30 or less from the viewpoint of obtaining a toner having a high image density and high durability, but is preferably 28 or less, and preferably 27 or less. More preferably. The variation coefficient of the particle size distribution can be calculated according to the following formula from the particle size distribution obtained in the measurement of the volume-based particle size distribution.
Coefficient of variation = (standard deviation of particle size distribution / volume average particle size (D ₄ )) × 100
In order to set the volume median particle size (D ₅₀ ) and the coefficient of variation in the particle size distribution of the emulsified particles to the above specific values, for example, using the above-mentioned mixer, stirring is performed with the stirring strength (stirring as described above) For example, a method of increasing the neutralization degree of the dispersion, or a method appropriately combining these methods.

Electrophotographic toner and method for producing the same Next, (a) a step of obtaining a resin emulsion by the above production method, and (b) a step of aggregating the emulsion particles in the obtained resin emulsion (hereinafter referred to as agglomeration step). The toner for electrophotography of the present invention can be obtained by a method comprising the steps of uniting (hereinafter referred to as uniting step). The colorant may be contained in the resin emulsion as described above, or a dispersion of the colorant may be mixed with the resin emulsion to aggregate and coalesce.
In the coagulation step, the pH value in the system is preferably 2 to 10, more preferably 2 to 9, from the viewpoint of achieving both the dispersion stability of the mixed solution and the cohesiveness of fine particles such as the binder resin and the colorant. 3 to 8 are more preferable.
From the same viewpoint, the temperature in the system in the aggregation step is preferably equal to or lower than the glass transition point of the binder resin, and more preferably equal to or lower than −10 ° C.

In the aggregation step, it is preferable to add an aggregating agent in order to effectively perform aggregation. As the aggregating agent, a quaternary salt cationic surfactant, an organic aggregating agent such as polyethyleneimine, an inorganic aggregating agent such as an inorganic metal salt, an ammonium salt or a divalent or higher metal complex is used. Examples of inorganic metal salts include metal salts such as sodium sulfate, sodium chloride, calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, aluminum sulfate, polyaluminum chloride, polyaluminum hydroxide, Examples thereof include inorganic metal salt polymers such as calcium sulfide.
Examples of the ammonium salt include ammonium halide, ammonium sulfate, ammonium chloride, ammonium acetate, ammonium benzoate, and ammonium salicylate. Examples of the quaternary ammonium salt include tetraalkylammonium halide. From the viewpoint of productivity, ammonium sulfate. Preferred examples include ammonium chloride, tetraammonium bromide, and tetrabutylammonium bromide. These flocculants may be used individually by 1 type, and may be used in combination of 2 or more type.

The amount of the flocculant used varies depending on the valence of the charge of the flocculant to be used, but when a monovalent flocculant is used, from the viewpoint of cohesiveness, 2 to 50 wt. Parts by weight or less, preferably 3.5 parts by weight or more and 40 parts by weight or less, more preferably 3.5 parts by weight or more and 30 parts by weight or less.
The flocculant is preferably added after being dissolved in an aqueous medium, and it is preferable to sufficiently stir at the time of adding the flocculant and after the addition. The obtained agglomerated particles are subjected to a step of coalescing the agglomerated particles (a coalescence step).

In the coalescence process, the temperature in the system is preferably equal to or higher than the temperature in the system in the aggregation process, but the target toner particle size, particle size distribution, shape control, and particle fusing property From the viewpoint, the glass transition point of the binder resin is preferably not lower than the softening point + 20 ° C., more preferably not lower than the glass transition point + 5 ° C. and softening point + 15 ° C., and the glass transition point is not lower than 10 ° C. and softening point is not higher than 10 ° C. Further preferred. The stirring speed is preferably a speed at which the aggregated particles do not settle.
The coalescence process can be performed simultaneously with the aggregation process, for example, by continuously raising the temperature or by raising the temperature to a temperature at which aggregation and coalescence can be performed and then continuing stirring at that temperature.

Toner mother particles can be obtained by subjecting the obtained coalesced particles to a solid-liquid separation process such as filtration, a washing process, and a drying process as appropriate.
In the washing step, for the purpose of ensuring sufficient charging characteristics and reliability as a toner, it is preferable to use an acid to remove metal ions on the surface of the toner base particles, and 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 base particles is preferably adjusted to 1.5% by weight or less, more preferably 1.0% by weight or less, from the viewpoint of chargeability.

The electrophotographic toner of the present invention contains coalesced particles obtained as described above, and the content of the coalesced particles in the toner is 95 to 95 from the viewpoint of toner chargeability and fixability. It is preferably 100% by weight, and more preferably 96.5 to 99% by weight.
Further, from the viewpoints of high image quality and productivity, the volume median particle size (D ₅₀ ) of the toner particles is preferably 1 to 10 μm, more preferably 2 to 8 μm, and further preferably 3 to 7 μm. From the same viewpoint, the particle size distribution has a coefficient of variation (standard deviation of particle size distribution / volume-volume median particle size (D ₅₀ ) × 100) of preferably 25 or less, more preferably 23 or less, and even more preferably 22 or less, 19 The following is more preferable.
Further, the softening point of the toner is preferably 60 to 140 ° C., more preferably 60 to 130 ° C., and further preferably 60 to 120 ° C. from the viewpoint of low-temperature fixability. Moreover, it is preferable that the maximum peak temperature of the endotherm by a differential scanning calorimeter is 60-140 degreeC from the same viewpoint, More preferably, it is 60-130 degreeC, More preferably, it is 60-120 degreeC.

In the toner of the present invention, an auxiliary agent such as a fluidizing agent can be added to the surface of the coalesced particles as an external additive. Examples of the external additive include known fine particles such as silica fine particles whose surface is hydrophobized, titanium oxide fine particles, alumina fine particles, cerium oxide fine particles, carbon black and other inorganic fine particles, and polymer fine particles such as polycarbonate, polymethyl methacrylate and silicone. Can be used.
The blending amount of the external additive is preferably 1 to 5 parts by weight, and more preferably 1.5 to 3.5 parts by weight with respect to 100 parts by weight of the toner base particles before processing with the external additive. However, when hydrophobic silica is used as an external additive, it is preferable to use 1 to 3 parts by weight of hydrophobic silica with respect to 100 parts by weight of toner base particles before treatment with the external additive.

  Examples of the transfer medium (recording material) to which the electrophotographic toner of the present invention is applied include plain paper and OHP sheets used in electrophotographic copying machines and printers. The toner for electrophotography obtained by the present invention can be used as a one-component developer or as a two-component developer by mixing with a carrier.

Each property value was measured and evaluated by the following method.
[Acid value of resin]
Measured according to 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)).
[Softening point of resin and toner, maximum endothermic peak temperature and glass transition point]
(1) Softening point Using a flow tester (Shimadzu Corporation, “CFT-500D”), a 1 g sample was heated at a heating rate of 6 ° C./min, a load of 1.96 MPa was applied by a plunger, a diameter of 1 mm, Extrude from a 1 mm long nozzle. Plot the flow tester drop by the flow tester against the temperature, and let the softening point be the temperature at which half the sample flowed out.

(2) Maximum endothermic peak temperature Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the temperature was raised to 200 ° C., and the temperature of the sample cooled to 0 ° C. at a temperature drop rate of 10 ° C./min was raised. Measure at a rate of 10 ° C / min. Among the observed endothermic peaks, the temperature of the peak on the highest temperature side is defined as the highest endothermic peak temperature. When the maximum peak temperature is within 20 ° C. from the softening point, the peak temperature is taken as the melting point, and when it is 20 ° C. or more lower than the softening point, the peak is caused by the glass transition.

(3) Glass transition point A sample was heated to 200 ° C. using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), and the sample was cooled from that temperature to 0 ° C. at a temperature lowering rate of 10 ° C./min. Measured in ° C / min. When a peak is observed at a temperature 20 ° C. or more lower than the softening point, the peak temperature is measured. When a peak is not observed at a temperature 20 ° C. or higher lower than the softening point, a step is observed. The temperature at the intersection of the tangent line indicating the maximum slope of the curve and the extension line of the base line on the high temperature side of the step is read as the glass transition point. The glass transition point is a physical property peculiar to the amorphous part of the resin, and is generally observed in amorphous polyester, but is observed when amorphous part exists even in crystalline polyester. There is.

[Number average molecular weight of binder resin]
The molecular weight distribution is measured by gel permeation chromatography and the number average molecular weight is calculated by the following method.
(1) Preparation of sample solution The binder resin is dissolved in chloroform so that the concentration is 0.5 g / 100 ml. Subsequently, this solution is filtered using a fluororesin filter having a pore size of 2 μm [manufactured by Sumitomo Electric Industries, Ltd., “FP-200”] to remove insoluble components to obtain a sample solution.

(2) Molecular weight distribution measurement Using the following apparatus, chloroform is flowed at a flow rate of 1 ml per minute, and the column is stabilized in a constant temperature bath at 40 ° C. 100 μl of the sample solution is injected therein and measurement is performed. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. In this calibration curve, several types of monodisperse polystyrene (2.63 × 10 ³ , 2.06 × 10 ⁴ , 1.02 × 10 ⁵ manufactured by Tosoh Corporation), 2.10 × manufactured by GL Sciences Inc. 10 ³ , 7.00 × 10 ³ , 5.04 × 10 ⁴ ) are used as standard samples.
Measuring device: CO-8010 (manufactured by Tosoh Corporation)
Analysis column: GMHLX + G3000HXL (manufactured by Tosoh Corporation)

[Particle size of emulsified particles]
Using a laser diffraction particle size measuring instrument (HORIBA, “LA-920”), distilled water is added to the measurement cell, the relative refractive index to water is 1.2, and the absorbance is obtained at a concentration within an appropriate range. From the obtained particle size distribution, the median diameter (that is, the volume median particle size (D ₅₀ )), the volume average particle size (D ₄ ), and the standard deviation are measured and calculated. The coefficient of variation is calculated according to the following formula.
Coefficient of variation = (standard deviation of particle size distribution / volume average particle size (D ₄ )) × 100

[Solid concentration of emulsion]
Using an infrared moisture meter (Ketto Science Laboratory Co., Ltd .: FD-230), 5 g of the emulsion was wet at a drying temperature of 150 ° C. and in a measurement mode 96 (monitoring time 2.5 minutes / variation width 0.05%). Measure the moisture content of the base. The solid content was calculated according to the following formula.
Solid content (%) = 100-M
M: wet base moisture (%) = [(W−W0) / W] × 100
W: Sample weight before measurement (initial sample weight)
W0: Sample weight after measurement (absolute dry weight)

[Toner particle size]
Measuring instrument: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 50 μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter)
Electrolyte: Isoton II (Beckman Coulter)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) is dissolved in the electrolytic solution to a concentration of 5% by weight to obtain a dispersion.
Dispersion condition: 10 mg of a measurement sample is added to 5 mL of the dispersion, and dispersed for 1 minute with an ultrasonic disperser, then 25 mL of an electrolyte is added, and further dispersed for 1 minute with an ultrasonic disperser. Prepare a dispersion.
Measurement conditions: After adjusting the particle size of 30,000 particles to a concentration that can be measured in 20 seconds by adding the sample dispersion to 100 mL of the electrolytic solution, 30,000 particles are measured, and the particle size distribution is determined. Determine the volume median particle size (D ₅₀ ). Further, the coefficient of variation of the toner is calculated according to the following formula.
Coefficient of variation = (standard deviation of particle size distribution / volume median particle size (D ₅₀ )) × 100

Production Example 1 Production of Polyester Resin A Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 8320 g, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) ) 80 g of propane, 1592 g of terephthalic acid and 32 g of dibutyltin oxide (esterification catalyst) were reacted at 230 ° C. under normal pressure for 5 hours under a nitrogen atmosphere, and further reacted under reduced pressure. After cooling to 210 ° C., 1672 g of fumaric acid and 8 g of hydroquinone were added and reacted for 5 hours, and further reacted under reduced pressure to obtain polyester resin A. Polyester resin A had a softening point of 110 ° C., a glass transition point of 66 ° C., an acid value of 24.4 mgKOH / g, and a number average molecular weight of 3760.

Production Example 2 Production of Polyester Resin B 17500 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) ) 16250 g of propane, 11454 g of terephthalic acid, 1608 g of dodecenyl succinic anhydride, 4800 g of trimellitic anhydride and 15 g of dibutyltin oxide are placed in a four-necked flask equipped with a nitrogen inlet tube, a dehydrating tube, a stirrer and a thermocouple, and a nitrogen atmosphere Below, it stirred at 220 degreeC and made it react until the softening point measured based on ASTM D36-86 reached 120 degreeC, and the polyester resin B was obtained. Polyester resin B had a softening point of 121 ° C., a glass transition point of 65 ° C., an acid value of 18.5 mgKOH / g, and a number average molecular weight of 3394.

Production Example 3 Production of Masterbatch 1 70 parts by weight of the fine powder of polyester resin A obtained in Production Example 1 and slurry pigment of copper phthalocyanine (ECB-301: solid content 46.2% by weight) manufactured by Dainichi Seika Co., Ltd. It was charged in a Henschel mixer so as to be part by weight, mixed for 5 minutes and wetted. Next, this mixture was charged into a kneader mixer and gradually heated. The resin was melted at approximately 90 to 110 ° C. and kneaded in a state where water was mixed, and kneading was continued at 90 to 110 ° C. for 20 minutes while water was evaporated.
Further, the kneading was continued at 120 ° C. to evaporate the remaining water, followed by dehydration drying. Further, kneading was continued at 120 to 130 ° C. for 10 minutes. After cooling, the mixture was further kneaded with a heated three roll, cooled and coarsely crushed to obtain a crushed product (master batch 1) of a high-concentration colored composition containing a blue pigment at a concentration of 30% by weight. When this was placed on a slide glass, heated and melted, and observed with a microscope, all pigment particles were finely dispersed, and no coarse particles were observed.

Example 1 Production of Resin Emulsion 1 In a stirring tank (lower member 3 in FIG. 1) of a planetary mixer (manufactured by PRIMIX: 5 L TK Hibismix), 640 g of polyester resin A, 420 g of polyester resin B, master 200 g of batch 1 (the softening point of the mixed resin obtained by mixing and melting the resins used in the polyester resin A, the polyester resin B, and the master batch 1 at the above-mentioned mixing ratio was 114 ° C., and the glass transition point was 64 ° C.), and anion Surfactant “Neopelex G-15 (Kao Corporation)” 80 g of sodium dodecylbenzenesulfonate (solid content: 15% by weight) and nonionic surfactant “Emulgen 430 (Kao Corporation)” polyoxy 12 g of ethylene (26 mol) oleyl ether (HLB: 16.2) and 5 wt% aqueous potassium hydroxide solution 5 1 g, with the above planetary mixer (made by PRIMIX: 5L TK Hibismix) where the biaxial stirring blade performs planetary motion, the stirring blade is in the direction opposite to the rotation direction as shown in FIG. Using a blade-shaped blade having a twisted shape, it was dispersed at 25 ° C. under stirring at a stirring peripheral speed of 1.2 m / sec (spinning peripheral speed: 0.7 m / sec, revolving peripheral speed: 0.5 m / sec). Then, it heated up to 95 degreeC and neutralized for 2 hours. Subsequently, 2276 g of deionized water was added dropwise at 12 g / min (1 g / min per 100 g of resin) for emulsification. The obtained emulsion was cooled to room temperature and passed through a 200 mesh (mesh opening: 105 μm) wire mesh to obtain a finely divided resin emulsion (1). The volume-average particle size (D ₅₀ ) of the resin particles in the obtained resin emulsion (1) was 0.13 μm, the coefficient of variation on a volume basis was 25, and no resin component remained on the wire mesh. The results are shown in Table 1.

Example 2
A resin emulsion (2) was prepared in the same manner as in Example 1 except that the stirring peripheral speed of the stirring blade of the planetary mixer was 0.4 m / sec. Table 1 shows the volume-median particle size (D ₅₀ ) of the resin particles in the obtained resin emulsion (2) and the coefficient of variation on a volume basis. Also, no resin component remained on the wire mesh.

Example 3
A resin emulsion (3) was prepared in the same manner as in Example 1 except that the stirring blades of the planetary mixer were flat blades that were not twisted. Table 1 shows the volume-median particle size (D ₅₀ ) of the resin particles in the obtained resin emulsion (3) and the coefficient of variation on a volume basis. Also, no resin component remained on the wire mesh.

Example 4
In Example 1, the resin emulsion (4) was prepared in the same manner as in Example 1 except that the amount of the “5 wt% potassium hydroxide aqueous solution” during emulsification was 370 g and the amount of deionized water dropped was 2,449 g. Prepared. Table 1 shows the volume-median particle size (D ₅₀ ) of the resin particles in the obtained resin emulsion (4) and the coefficient of variation on a volume basis. Also, no resin component remained on the wire mesh.

Reference Example 5
In Example 1, a resin emulsion (5) was prepared in the same manner as in Example 1 except that instead of the Kai-type stirrer having a 5-liter stainless steel kettle, the peripheral speed was 1.2 m / sec. did. Table 1 shows the volume-median particle size (D ₅₀ ) of the resin particles in the obtained resin emulsion (5) and the coefficient of variation on a volume basis. Also, no resin component remained on the wire mesh.

Comparative Example 1
In Reference Example 5, a resin emulsion (6) was prepared in the same manner as in Reference Example 5 except that the amount of the “5 wt% potassium hydroxide aqueous solution” at the time of emulsification was 275 g and the dropping amount of deionized water was 2,539 g. Was prepared. Table 1 shows the volume-median particle size (D ₅₀ ) of the resin particles in the obtained resin emulsion (6) and the coefficient of variation on a volume basis. Moreover, the resin component was confirmed on the wire mesh.

Comparative Example 2
In Reference Example 5, a resin emulsion (7) was prepared in the same manner as in Reference Example 5 except that the stirring peripheral speed of the chi-type stirrer was changed to 0.4 m / sec. Table 1 shows the volume-median particle size (D ₅₀ ) of the resin particles in the obtained resin emulsion (7) and the coefficient of variation on the volume basis. Further, no resin component remained on the wire mesh.

In addition, the stirring conditions of the mixer used by the said Example and comparative example were as follows.
[Stirring conditions]
Planetary mixer ( TK Hibismix)
Revolution: Diameter = φ242mm Rotation speed = 40r / min
Rotation: Diameter = φ132mm Rotation speed = 100r / min
(Revolution and rotation are the same direction)
The peripheral speed of the planetary mixer is the sum of the peripheral speed of revolution and the peripheral speed of rotation.
Chi-type agitator blade: Diameter = φ115 mm, rotation speed = 200 r / min
The peripheral speed (m / s) was determined by the following formula.
Peripheral speed (m / s) = diameter (m) × π × rotational speed (r / min) / 60

For each of the resin emulsions (1) to (7) obtained in Examples 1 to 4, Reference Example 5 and Comparative Examples 1 and 2, the emulsion concentration was measured as follows. The results are shown in Table 1. Show.
[Evaluation of reflection density of resin emulsion]
Fill the resin emulsion with a hole of φ8mm and depth 8mm provided on the acrylic plate, and use a colorimeter (Specteye, manufactured by Gretag-Macbeth), the light emission conditions are standard light source D50, observation field of view 2 °, density standard DIN In NB, the color is measured with an absolute white reference, and the reflection density is measured.

Example 6 (Production of toner)
500 g of the resin emulsion (1) was placed in a 2 liter container and stirred at room temperature. Next, 25 g of ammonium sulfate (special grade made by Sigma-Aldrich Japan Co., Ltd.) as a flocculant dissolved in 1179 g of deionized water was added dropwise at room temperature over 10 minutes while stirring at 100 / min with a Kai-type stirrer. The temperature was raised from room temperature to 80 ° C. over 1 hour, and maintained at 80 ° C. for 3 hours. Next, it was cooled to room temperature with stirring. The contents were suction filtered, washed, and dried to obtain colored resin particles. The volume median particle size (D ₅₀ ) of the colored resin particles was 4.8 μm, the coefficient of variation was 19, the softening point was 99.8 ° C., and the glass transition point was 53.7 ° C.
Toner (1) was prepared by adding 1.0 part by weight of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., R972, number average particle diameter 16 nm) to 100 parts by weight of the colored resin fine particles using a Henschel mixer.

Examples 7 to 9, Reference Example 10 and Comparative Examples 3 and 4 (Production of toner)
Toners (2) to (7) corresponding to the respective resin emulsions (2) to (7) were prepared in the same manner as in Example 6 except that each of the resin emulsions (2) to (7) was used. Table 2 shows the volume-median particle diameter (D ₅₀ ), coefficient of variation, softening point, and glass transition point of each colored resin particle.

For each of the obtained toners (1) to (7), image density and durability were evaluated by the following methods. The results are shown in Table 2.
[Image density]
Toner was mounted on a non-magnetic one-component developing device “MICROLINE 5400” (Oki Data Co., Ltd.), and a solid image was printed with an adhesion amount of 0.3 mg / cm ² . Using the colorimeter (Gretag-Macbeth, SpectroEye), the solid image thus obtained was measured with an absolute white reference in a standard light source D50, an observation field of view 2 °, and a density reference DIN NB. It was measured.

[durability]
Toner was mounted on a non-magnetic one-component developing device “MICROLINE 5400” (manufactured by Oki Data Corporation), and 10,000 sheets of a chart with a printing rate of 5% were printed. After printing, the state of occurrence of fusion of residual toner on the surface of the photosensitive drum and the influence on the printed image are visually observed, and durability (filming resistance) is evaluated according to the following evaluation criteria.
A: Toner fusion has not occurred. O: Toner fusion is confirmed at 1 to 2 places on the photoreceptor, but there is no effect on the image. Δ: Toner fusion is confirmed at 3 to 5 places on the photoreceptor. However, there is no influence on the image. X: Toner fusion is confirmed on six or more places on the photoreceptor, and the image has a defect.

  The resin emulsion of the present invention and the production method thereof can be suitably used for production of an electrophotographic toner used in electrophotography, electrostatic recording method, electrostatic printing method and the like.

The perspective view which showed an example of the planetary mixer used in this invention. The partially enlarged view of an example of the planetary mixer used in this invention. The partially expanded view of another example of the planetary mixer used in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Stirring tank 2 ... Upper part of stirring tank 3 ... Lower part 4 and 5 of stirring tank ... Stirring blade 6 ... Rotor

Claims (5)

An electrophotographic toner production method comprising: (a) a step of obtaining a resin emulsion; and (b) a step of aggregating and coalescing the emulsified particles in the obtained resin emulsion,
The step of obtaining a resin emulsion in step (a) is: (1) A step of dispersing a raw material containing a binder resin containing a polyester and a colorant in a basic aqueous medium, (2) the obtained dispersion have a step, emulsifying in an aqueous medium by adding an aqueous solution process is neutralized by stirring, and (3) the neutralized dispersion, stirring at least the step (2), revolution shaft A method for producing an electrophotographic toner, wherein two or more rotation shafts are connected to each other, and a stirring blade provided on each rotation shaft performs a planetary motion. A mixer in which two or more rotation shafts are connected to the revolution shaft and the stirring blades provided on the respective rotation shafts perform planetary motion for stirring in the step (2) and the steps (1) and / or (3). The method for producing an electrophotographic toner according to claim 1, wherein the toner is used . The method for producing an electrophotographic toner according to claim 1, wherein the basic aqueous medium does not contain an organic solvent. The method for producing an electrophotographic toner according to claim 1, wherein the stirring peripheral speed of the stirring blade provided on the rotation shaft of the mixer is 0.5 to 5 m / sec. The method for producing an electrophotographic toner according to claim 1, wherein at least one of the stirring blades provided on the rotation shaft of the mixer has a shape twisted in a direction opposite to the rotation direction of the rotation.

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