JP4832274B2 - Resin emulsion for toner - Google Patents

Description

  The present invention relates to 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.

In the field of electrophotographic toner, with development of an electrophotographic system, development of a toner corresponding to high image quality and high speed is required. From the viewpoint of high image quality, it is necessary to reduce the particle size of the toner, and so-called chemical toners obtained by chemical methods such as a polymerization method and an emulsification dispersion method have been proposed instead of the conventional melt-kneading and pulverization methods. In view of the small particle size and sharp particle size distribution. In such a method, the toner particles are usually prepared by a step of dispersing the raw material of the toner as primary particles using a surfactant and then aggregating and coalescing the particles to the toner particle size.
For example, Patent Document 1 includes toner particles composed of a resin and a colorant, and includes an aliphatic hydrocarbon group having 10 to 22 carbon atoms or a distyrenated phenyl group, and an alkylene group having 2 to 6 carbon atoms (addition mole number 1 to 1). 15), it is described that the fixing property is improved by a toner for developing an electrostatic image containing 1 to 1000 ppm of a compound having the formula (15). Patent Document 2 discloses a low-temperature fixability by a method of aggregating and coalescing an emulsion obtained by emulsifying a crystalline polyester resin using a dispersant such as dodecylbenzenesulfonic acid in a basic aqueous medium. In other words, it is described that an electrophotographic toner excellent in the above can be obtained.
However, in the production of these toners, coarse particles may be generated at the time of aggregation, and the particle size distribution of the obtained toner becomes wide. Even if such coarse particles are removed, the toner yield is consequently reduced. There was a problem such as lowering.

JP 2004-287422 A JP 2004-287149 A

  The present invention can suppress the generation of coarse particles, the toner emulsion for toners capable of obtaining a toner having a narrow particle size distribution, a method for producing the same, the generation of coarse particles obtained using the resin emulsion, is suppressed, The present invention relates to an electrophotographic toner having a narrow particle size distribution and a method for producing the toner in a high yield.

The present invention
(1) A resin emulsion for toner containing a binder resin containing polyester and a nonionic surfactant represented by the following formula (1).
R ¹ O (CH ₂ CH ₂ O) nH (1)
(In the formula, R ¹ represents an aliphatic hydrocarbon group having 8 to 22 carbon atoms, and n represents an average added mole number of 18 to 60.)
(2) (a) a step of dispersing a binder resin containing polyester in a basic aqueous medium in the presence of the nonionic surfactant represented by the above formula (1);
(B) a step of neutralizing the dispersion obtained in the step (a), and (c) an aqueous solution is added to the dispersion neutralized in the step (b) to add the binder resin in an aqueous medium. A step of phase inversion emulsification,
A method for producing a resin emulsion for toners, comprising:

(3) Electrophotographic toner obtained by aggregating and coalescing the emulsified particles in the toner resin emulsion described in (1) above, and (4) (A) resin emulsification by the method described in (2) above. A step of producing a liquid; and
(B) A step of aggregating and coalescing the emulsified particles in the resin emulsion obtained in step (a) in an aqueous medium,
A method for producing an electrophotographic toner comprising:
I will provide a.

  According to the present invention, the generation of coarse particles is suppressed, and an electrophotographic toner having a narrow particle size distribution can be produced in a high yield.

[Resin emulsion for toner and method for producing the same]
The resin emulsion for toner of the present invention and the production method thereof will be described below.
(Resin emulsion for toner)
The resin emulsion for toner of the present invention contains a binder resin containing polyester and a nonionic surfactant represented by the general formula (1).

The binder resin containing polyester contains polyester from the viewpoints of toner fixability and durability. The content of the polyester is preferably 60% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more, and substantially 100% by weight in the binder resin from the viewpoint of fixability and durability. Is more preferable.
Examples of the resin other than polyester include known resins used for toner, such as styrene-acrylic copolymer, epoxy, polycarbonate, polyurethane and the like.

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 charging ratio of alcohol and carboxylic acid, the temperature of condensation polymerization, and the 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.

In the present invention, polyester includes not only polyester but also polyester modified to such an extent that its properties are not substantially impaired. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. And a composite resin having two or more kinds of resin units including a polyester unit.
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 each resin contained. , Acid value and number average molecular weight, and each value is preferably the same value as the polyester.

  Furthermore, in the present invention, the binder resin 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 ° C. or higher and 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.

Nonionic surfactant What is represented by following General formula (1) is used as a nonionic surfactant.
R ¹ O (CH ₂ CH ₂ O) nH (1)
(In the formula, R ¹ represents an aliphatic hydrocarbon group having 8 to 22 carbon atoms, and n represents an average added mole number of 18 to 60.)
In the general formula (1), R ¹ represents an aliphatic hydrocarbon group having 8 to 22 carbon atoms, and is preferably an aliphatic hydrocarbon group having 8 to 18 carbon atoms from the viewpoint of adsorptivity and detergency.

  Specific examples of such aliphatic hydrocarbon groups include n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tetradecyl group, and n-pentadecyl group. , N-hexadecyl group, n-octadecyl group, n-docosadecyl group, n-icosyl group and other alkyl groups, octenyl group, decenyl group, dodecenyl group, hexadecenyl group, icosenyl group and other unsaturated aliphatic hydrocarbon groups, octyl Examples thereof include cycloaliphatic hydrocarbon groups such as cyclohexyl group and nonylcyclohexyl group. These aliphatic hydrocarbon groups may be linear or branched.

In the general formula (1), n is an average addition mole number of 18 to 60, but from the viewpoint of emulsifying property and cohesiveness, it is preferably a number of 20 to 60, more preferably a number of 25 to 60, still more preferably. It is a number from 30 to 60.
In the present invention, from the above viewpoint, as the nonionic surfactant represented by the formula (1), R ¹ is an aliphatic hydrocarbon group having 8 to 18 carbon atoms, and n is a number of 20 to 60. preferably a compound, more preferably, R ¹ is an aliphatic hydrocarbon group having 8 to 18 carbon atoms, compounds wherein n is a number from 25 to 60.

Specifically, as the nonionic surfactant, from the above viewpoint, polyoxyethylene (average number of added moles: 18 to 60 mol, preferably 20 to 60 mol, more preferably 25 to 60 mol) lauryl ether, Polyoxyethylene (average added mole number: 18 to 60 mole, preferably 20 to 60 mole, more preferably 25 to 60 mole) oleyl ether, polyoxyethylene (average added mole number: 18 to 60 mole, preferably 20 to 20 mole) 60 mol, more preferably 25 to 60 mol) stearyl ether and the like are preferable.
The nonionic surfactant is preferably 5 parts by weight or less, more preferably 0.5 to 5 parts with respect to 100 parts by weight of the binder resin in the resin emulsion from the viewpoints of emulsifying properties and aggregation properties. It is contained in an amount of parts by weight, more preferably 0.5 to 3 parts by weight.
By using such a nonionic surfactant, it is possible to obtain a toner having no coarse particles and a narrow particle size distribution.
In the range where the effects of the present invention are not impaired, a part of the nonionic surfactant represented by the formula (1), that is, 10 mol% or less of the whole is added with propylene oxide. Good.

Other Additives In the present invention, other surfactants can be contained together with the nonionic surfactant as necessary. Examples of other surfactants include anionic surfactants such as sulfate ester type, sulfonate type, phosphate ester type, and soap type; cationic surfactants such as amine salt type and quaternary ammonium salt type A nonionic surfactant other than the nonionic surfactant represented by the above formula (1) such as polyethylene glycol-based, alkylphenol ethylene oxide adduct-based, polyhydric alcohol-based and the like. Among these, ionic surfactants such as anionic surfactants and cationic surfactants are preferable.

Specific examples of the anionic surfactant include dodecyl benzene sulfonic acid, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium alkyl ether sulfate, sodium alkyl naphthalene sulfonate, sodium dialkyl sulfosuccinate and the like.
Specific examples of the cationic surfactant include alkylbenzene dimethyl ammonium chloride, alkyl trimethyl ammonium chloride, distearyl ammonium chloride and the like.
Although the said surfactant may be used individually by 1 type, you may use it in combination of 2 or more type.
In the present invention, it is preferable to use an anionic surfactant together with the nonionic surfactant represented by the formula (1) from the viewpoint of emulsification. When an anionic surfactant is used in combination, the anionic surfactant is preferably 5 parts by weight or less, more preferably 100 parts by weight or less in the resin emulsion, from the viewpoint of emulsifying properties. Is contained in an amount of 0.5 to 3 parts by weight.

The emulsified particles in the resin emulsion may contain additives such as a colorant, a release agent, and a charge control agent, if necessary, in addition to the binder resin and the nonionic surfactant.
The colorant is not particularly limited, and any known colorant can be used. 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, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, Acridine, Xanthene, Azo Benzoquinone, azine, anthraquinone, indico, thioindico, phthalocyanine, aniline black, thiazole One of the various dyes and the like, alone or in combination of two or more can be used.
The content of the colorant is preferably 20 parts by weight or less, and more preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles.

As release agents, low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point upon heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide; carnauba Plant waxes such as wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; mineral and petroleum systems such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax Wax etc. are mentioned.
The content of the release agent is preferably 1 to 20 parts by weight and more preferably 2 to 15 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles in consideration of the addition effect and the adverse effect on the chargeability. .
The release agent is preferably used by being dispersed in an aqueous medium from the viewpoint of dispersibility and agglomeration with resin particles.

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.
The content of the charge control agent is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and more preferably 3 parts by weight or less with respect to 100 parts by weight of the resin constituting the resin particles.

The resin emulsion of the present invention is preferably such that the binder resin, nonionic surfactant, and if necessary, other additives are dispersed in a non-organic solvent-based aqueous medium. Here, the aqueous medium is one containing water as a main component, that is, one containing 50% or more of water. From the environmental viewpoint, the content of water in the aqueous medium is preferably 80% by weight or more, more preferably 90% by weight or more, and further preferably 100% by weight.
Examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Among these, from the viewpoint of preventing mixing into the toner, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol, which are organic solvents that do not dissolve the resin, can be used. In the present invention, it is preferable to atomize the binder resin using only water without substantially using an organic solvent.

  The volume median particle size (D50) of the resin particles in the resin emulsion of the present invention is preferably 0.02 to 2 μm, more preferably 0.05 to 2 in order to perform uniform aggregation in the subsequent aggregation treatment. It is 1 μm, more preferably 0.05 to 0.6 μm. Here, “volume median particle size (D50)” 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 measuring method is as described later.

(Method for producing resin emulsion for toner)
The resin emulsion for toner of the present invention is preferably produced by a method having the following steps (a) to (c).
(A) A step of dispersing a binder resin containing polyester in a basic aqueous medium in the presence of the nonionic surfactant represented by the formula (1) (b) obtained in step (a). Steps of neutralizing the dispersion (c) Step of emulsifying the above binder resin in an aqueous medium by adding an aqueous liquid to the dispersion neutralized in the steps (c) and (b)

Step (a) Step (a) is a step in which a binder resin containing polyester is dispersed in a basic aqueous medium in the presence of the nonionic surfactant represented by the formula (1).
The binder resin containing polyester and the nonionic surfactant are as described above.
The basic aqueous medium in which the binder resin is dispersed refers to an aqueous medium containing a basic compound and not composed of an organic solvent alone, and the aqueous medium is as described above.

  The basic aqueous medium preferably has a basic compound concentration of 1 to 20% by weight, more preferably 1 to 10% by weight, and more preferably 1.5 to 7.5% by weight. Further preferred. As for the basic compound to be used, it is preferable to use an alkali that enhances the surface activity when the polyester becomes a salt. Specifically, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, salts of weak acids such as carbonates and acetates thereof, or partially neutralized salts, and inorganic basic compounds such as ammonia, It may be any of organic basic compounds such as 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.

  In the step (a), a mixture of various additives such as a binder resin, a nonionic surfactant, and other surfactants and colorants used as necessary is added to a basic aqueous medium. When the anionic surfactant is used in combination with the nonionic surfactant, the amount of the anionic surfactant present in the nonionic surfactant is All are the same as the amount described in the above description of the resin emulsion.

  In addition, from the viewpoint of uniformly dispersing, in the step (a), it is preferable to perform the dispersion treatment at a temperature lower than the softening point of the resin particles. That is, the resin particles are preferably subjected to a dispersion treatment at a temperature lower than the softening point, more preferably 50 ° C. lower than the softening point (hereinafter referred to as “softening point −50 ° C.”). Adhesion can be suppressed and a uniform resin dispersion can be prepared. Further, the lower limit temperature of the dispersion treatment is preferably higher than 0 ° C., more preferably 10 ° C. or higher, from the viewpoint of fluidity of the medium and production energy of the resin emulsion. When using a mixed resin, the softening point of the mixed resin mixed and melted at the mixing ratio is defined as the softening point of the binder resin. Moreover, when using a masterbatch, it is set as the softening point of mixed resin including the resin used for it.

Step (b) Step (b) is a step of neutralizing the dispersion obtained in step (a).
In the step (b), from the viewpoint of uniformly neutralizing the resin, it is preferable to carry out neutralization by stirring for a certain time, and the stirring time is preferably 30 minutes or more, more preferably 1 hour or more.
Further, the neutralization temperature is preferably a binding because neutralization is sufficiently performed, generation of large emulsified particles is suppressed by the emulsification treatment in the next step, and no special apparatus is required for heating. The temperature is not lower than the glass transition point of the resin and not higher than the softening point, more preferably not lower than the glass transition point + 10 ° C. and not higher than the softening point −5 ° C.

  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 still more preferably 70 to 100%. 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, while stirring the resin dispersion dispersed in the step (a), for example, as a binder resin, a polyester having a glass transition point of about 60 to 65 ° C. and a softening point of about 110 to 120 ° C. Is used, the temperature is raised to a temperature of about 90 to 100 ° C., and neutralization is carried out by holding at that temperature for an appropriate time until a predetermined degree of neutralization is reached.

Step (c) Step (c) is a step in which an aqueous liquid is added to the dispersion neutralized in the step (b) to phase-emulsify the resin in the aqueous medium. After neutralizing in the step (b), a resin emulsion can be produced by adding an aqueous medium at a temperature equal to or higher than the glass transition point of the binder resin, and carrying out phase inversion emulsification.
In this emulsification step, from the viewpoint of preparing a fine resin emulsion, the resin dispersion neutralized in step (b) is maintained at a temperature above the glass transition temperature of the resin and below the softening point and stirred. However, it is preferable to add an aqueous liquid thereto and emulsify in an aqueous medium.
In addition, by performing the emulsification at a temperature within the above range, the emulsification is performed smoothly and no special apparatus is required for heating. From this, the temperature at the time of emulsification is preferably a glass transition point of the binder resin + 10 ° C or higher, and a softening point of -5 ° C or lower.

  In this step, the resin content in the dispersion is preferably about 50 to 90% by weight, more preferably 50 to 80% by weight immediately before emulsification, in view of easy phase inversion. Here, “immediately before the start of emulsification” refers to a point in time when the viscosity in the system is highest in all steps. 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.

Examples of the aqueous liquid used for emulsification include the same ones as described in the explanation of the basic aqueous medium in the step (a). 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 amount of the aqueous medium is preferably 100 to 2,000 parts by weight, and 150 to 1,500 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles, from the viewpoint of obtaining uniform aggregated particles in the subsequent agglomeration treatment. More preferred.
The solid content concentration of the resin emulsion thus obtained is 5 to 50 from the viewpoint of causing stability of the emulsion and handling of the resin emulsion in the aggregation step to be performed later, and uniform aggregation. % By weight is preferred, 5 to 45% by weight is more preferred, and 10 to 40% by weight is even more preferred.

  As another method for obtaining the resin emulsion of the present invention, for example, first, a polycondensable monomer is used as the target resin particle raw material in the presence of the nonionic surfactant of the above formula (1) in an aqueous medium. Examples thereof include a method of emulsifying and dispersing by, for example, mechanical shearing and ultrasonic waves. At this time, if necessary, additives such as a polycondensation catalyst and a surfactant are also added to the water-soluble medium. And polycondensation is advanced by, for example, heating the solution. For example, when the resin is polyester, the above-mentioned polyester polycondensable monomer and polycondensation catalyst can be used, and the above-mentioned surfactants can be used similarly.

Usually, polycondensation resins do not proceed in an aqueous medium in principle because they are dehydrated during polymerization. However, for example, when a polycondensable monomer is emulsified in an aqueous medium together with a surfactant that causes micelles to form in the aqueous medium, the monomer is placed in a micro hydrophobic field in the micelle. Thus, dehydration occurs, and the generated water can be discharged into an aqueous medium outside the micelles to allow polymerization to proceed. In this way, a dispersion in which the resin particles of the polycondensation resin are emulsified and dispersed in an aqueous medium with a low energy is obtained.
The toner obtained by using the resin emulsion obtained by the method for producing the resin emulsion has a narrow particle size distribution with the generation of coarse particles being suppressed, and obtains such toner in a high yield. be able to.

[Electrophotographic toner and method for producing the same]
(Method for producing electrophotographic toner)
The toner for electrophotography of the present invention is obtained by aggregating and coalescing the emulsified particles in the toner resin emulsion. Specifically, (a) a step of producing a resin emulsion by the method for producing a resin emulsion for toner, and (b) emulsified particles in the resin emulsion obtained in step (a) in an aqueous medium. Thus, it is preferable to obtain it by a method for producing an electrophotographic toner comprising the steps of aggregating and coalescing.
The step of producing the resin emulsion by the method for producing the resin emulsion for toner in the step (a) is as described above.
Step (b) is a step of agglomerating and coalescing the emulsified particles in the resin emulsion obtained in step (a) in an aqueous medium. Hereinafter, the aggregation / unification process will be described.

In the aggregating step (b), the pH value in the system in the aggregating step is preferably 2 to 10, from the viewpoint of achieving both the dispersion stability of the mixed solution and the aggregating properties of fine particles such as a binder resin. 9 is more preferable, and 3 to 8 is 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. In the present invention, it is preferable to use a monovalent salt as the flocculant from the viewpoint of achieving highly accurate toner particle size control and a sharp particle size distribution. Here, the monovalent salt means that the valence of the metal ion or cation constituting the salt is 1. As the monovalent salt, organic flocculants such as quaternary salt cationic surfactants, inorganic flocculants such as inorganic metal salts and ammonium salts are used. From the viewpoint of achieving particle size control and a sharp particle size distribution, a water-soluble nitrogen-containing compound having a molecular weight of 350 or less is preferably used.

  The water-soluble nitrogen-containing compound having a molecular weight of 350 or less is preferably a compound that exhibits acidity from the viewpoint of rapidly agglomerating resin particles, and a pH value at 25 ° C. of a 10 wt% aqueous solution thereof is 4-6. Are preferable, and 4.2 to 6 are more preferable. From the viewpoint of chargeability at high temperature and high humidity, the molecular weight is preferably 350 or less, more preferably 300 or less. Examples of such water-soluble nitrogen-containing compounds include ammonium salts such as ammonium halide, ammonium sulfate, ammonium acetate, ammonium benzoate and ammonium salicylate, and quaternary ammonium salts such as tetraalkylammonium halide. From the viewpoint of properties, ammonium sulfate (pH value of 10 wt% aqueous solution at 25 ° C., hereinafter referred to as pH value: 5.4), ammonium chloride (pH value: 4.6), tetraammonium bromide (pH value: 5.6) ) And tetrabutylammonium bromide (pH value: 5.8).

The amount of the flocculant used varies depending on the valence of the charge of the flocculant used, but when a monovalent flocculant is used, 2 to 50 wt. Part is preferable, 3.5 to 40 parts by weight is more preferable, and 3.5 to 30 parts by weight is further preferable.
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 addition of the flocculant is performed after adjusting the pH in the system in order to perform uniform aggregation, and at a temperature below the glass transition point of the resin constituting the resin particles, preferably at a glass transition point of −10 ° C. or lower. It is desirable to do in. The flocculant may be added at once, or may be added intermittently or continuously. Furthermore, it is preferable to sufficiently stir at the time of adding the flocculant and after the addition is completed.

In the present invention, it is preferable to add a surfactant after agglomerating the resin emulsified particles, and an alkyl ether sulfate, an alkyl sulfate, and a linear alkylbenzene sulfonate represented by the following formula (2): More preferably, at least one selected from the group consisting of:
^{_{R 2 -O- (CH 2 CH 2}} O) pSO 3 M 1 (2)
(In the formula, R ² represents an alkyl group, p represents an average added mole number of 0 to 15, and M ¹ represents a monovalent cation.)

In the formula (1), the alkyl group represented by R ² is preferably 6 to 20 carbon atoms, more preferably 8 to 18 carbon atoms, more preferably from the viewpoint of adsorptivity to aggregated particles and persistence to toner. Preferred are those having 8 to 15 carbon atoms, and specific examples include octyl group, decyl group, dodecyl group, tetradecyl group, pentadecyl group, octadecyl group and the like. p is an average number of added moles of 1 to 15, and is preferably 1 to 10, more preferably 1 to 5, from the viewpoint of particle size control. M ¹ is a monovalent cation, and is preferably sodium, potassium, or ammonium, more preferably sodium or ammonium, from the viewpoint of particle size control.

Further, the linear alkylbenzene sulfonate is not particularly limited, but from the viewpoint of the adsorptivity to the aggregated particles and the persistence to the toner, the formula (3)
R ³ —Ph—SO ₃ M ² (3)
(In the formula, R ³ represents a linear alkyl group, Ph is a phenyl group, and M ² is a monovalent cation. The linear alkyl group is a straight chain of R ^{2 in} the formula (2). The linear alkyl group includes, for example, an octyl group, a decyl group, a dodecyl group, a tetradecyl group, an octadecyl group, and the like. As the linear alkylbenzene sulfonate, These sodium sulfate salts are preferably used.

The alkyl ether sulfate, alkyl sulfate, or linear alkyl benzene sulfonate may be used singly or in combination of two or more.
The amount of the surfactant added is preferably from 0.1 to 15 parts by weight, more preferably from 0.1 to 15 parts by weight, based on 100 parts by weight of the resin constituting the aggregated particles, from the viewpoints of aggregation stopping properties and persistence to toner. 1 to 10 parts by weight, more preferably 0.1 to 8 parts by weight.
In the present invention, from the viewpoint of improving the image quality, the volume median particle size (D50) of the aggregated particles is preferably 1 to 10 μm, more preferably 2 to 10 μm, and further preferably 2 to 9 μm.
The obtained agglomerated particles are subjected to a step of coalescing the agglomerated particles (a coalescence step).

Coalescence process This process is a process of heating and coalescing the aggregated particles obtained in the aggregation process.
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 In view of the above, the glass transition point or higher of the binder resin is preferable, the softening point + 20 ° C. or lower is more preferable, the glass transition point + 5 ° C. or higher, the softening point + 15 ° C. or lower is more preferable, the glass transition point + 10 ° C. or higher, and the softening point +10. More preferably, it is not higher than ° C. 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.
From the viewpoint of high image quality, the volume-median particle size (D50) of the coalesced particles is preferably 1 to 10 μm, more preferably 2 to 10 μm, and even more preferably 3 to 9 μm.

The obtained coalesced particles become toner particles through a solid-liquid separation process such as filtration, a washing process, and a drying process. Here, in order to ensure sufficient charging characteristics and reliability as a toner, it is preferable to perform cleaning with an acid in order to remove metal ions on the toner surface in the cleaning step.
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 particles is preferably adjusted to 1.5% by weight or less, more preferably 1.0% by weight or less, from the viewpoint of chargeability of the toner.
As described above, by the toner manufacturing method of the present invention, the generation of coarse particles is suppressed, and an electrophotographic toner having a narrow particle size distribution can be manufactured in a high yield.

(Electrophotographic toner)
The electrophotographic toner of the present invention is obtained by aggregating and coalescing the emulsified particles in the resin emulsion for toner of the present invention, and can be preferably obtained by the above-described production method. The obtained electrophotographic toner has a small particle size suitable for high definition and high image quality, a narrow particle size distribution, and excellent charging characteristics and fixing properties.
The softening point of the electrophotographic toner of the present invention 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, 30-80 degreeC is preferable from a durable viewpoint, and, as for a glass transition point, 40-70 degreeC is more preferable. In addition, the measuring method of a softening point and a glass transition point is based on these measuring methods in resin.

In the toner of the present invention, an auxiliary agent such as a fluidizing agent can be added to the toner particle surface as an external additive. External additives include known fine particles such as silica fine particles, titanium 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 resin. Can be used.
The 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 before processing with the external additive.

From the viewpoint of high image quality, the volume median particle size (D50) of the toner particles is preferably 1 to 10 μm, more preferably 2 to 8 μm, and even more preferably 3 to 8 μm. Further, the CV values of the agglomerated particles, coalesced particles and toner particles described above are preferably 40 or less, more preferably 36 or less. The toner of the present invention preferably has the above particle diameter and CV value. Here, the particle size and particle size distribution of the toner particles can be measured by the method described later.
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.

In the following examples and the like, each property value was measured and evaluated by the following method.
[Acid value of resin]
Measured according to JIS K0070. However, the measurement solvent was a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Softening point and glass transition point of resin and toner]
(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) 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 −10 ° C. at a cooling rate of 10 ° C./min. Measure at 10 ° 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 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 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)

[Resin emulsion particles, aggregated particles, coalesced particles, toner particle size and particle size distribution]
(1) Measuring apparatus: Laser scattering type particle size measuring machine (LA-920, manufactured by HORIBA, Ltd.)
(2) Measurement conditions: Distilled water is added to the measurement cell, and the volume-median particle size (D50) and the volume average particle size (D ₄ ) are measured at a temperature where the absorbance falls within an appropriate range. The particle size distribution is indicated by a CV value (standard deviation of particle size distribution / volume average particle size (D ₄ ) × 100).

[Solid content concentration of resin 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)

Production Example 1 (Production of polyester A)
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 8,320 g, Polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane 80 g, terephthalic acid 1,592 g and dibutyltin oxide (esterification catalyst) 32 g Placed in a four-necked flask equipped with a nitrogen introduction tube, dehydration tube, stirrer and thermocouple at 230 ° C. under nitrogen atmosphere and normal pressure (101.3 kPa) The reaction was carried out for 5 hours, and further 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 A. Polyester 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 3,760.

Production Example 2 (Production of polyester B)
Polyoxypropylene (2.2) -2, 2-bis (4-hydroxyphenyl) propane 1750 g, polyoxyethylene (2.0) -2, 2-bis (4-hydroxyphenyl) propane 1625 g, terephthalic acid 1145 g, 161 g of dodecenyl succinic anhydride, 480 g of trimellitic anhydride and 26 g of tin 2-ethylhexanoate were placed in a four-necked flask equipped with a nitrogen inlet tube, a dehydrating tube, a stirrer, and a thermocouple. Stirring and reacting until the softening point measured in accordance with ASTM D36-86 reaches 120 ° C. yields polyester B. Polyester B had a softening point of 121 ° C., a glass transition point of 65 ° C., an acid value of 21 mgKOH / g, and a number average molecular weight of 3,394.

Example 3 (Manufacture of masterbatch A)
70 parts by weight of the fine powder of polyester A obtained in Production Example 1 and a copper phthalocyanine slurry pigment (ECB-301: solid content 46.2% by weight) manufactured by Dainichi Seika Co., Ltd. were added to a Henschel mixer so that the pigment content was 30 parts by weight. The mixture was mixed and wetted for 5 minutes. 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 coarsely pulverized product (masterbatch A) of a highly concentrated 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 A)
In a 5 liter stainless steel kettle, polyester A 800 g, polyester B 525 g, masterbatch A 250 g (resin used by mixing and melting the resins used in polyester A, polyester B and masterbatch A in the above blending ratio is 114 ° C., Glass transition point was 64 ° C.) and anionic surfactant “Neopelex G-15 (manufactured by Kao)” sodium dodecylbenzenesulfonate (solid content: 15% by weight) 100 g, nonionic surfactant As agents, 15 g of polyoxyethylene (average number of added moles: 50 mol) lauryl ether and 689 g of 5 wt% aqueous potassium hydroxide solution were dispersed at 25 ° C. with stirring at 200 r / min with a Kai-type stirrer. The contents were stabilized at 95 ° C. and held for 2 hours under stirring at 200 r / min with a chi-type stirrer. Subsequently, deionized water was added dropwise at 15 g / min while stirring at 200 r / min with a Kai-type stirrer, and a total of 2845 g was added. Further, the temperature in the system was maintained at 95 ° C. while deionized water was added dropwise. After cooling, resin emulsion A was obtained through a 150 mesh (mesh: 105 μm) wire mesh. The volume median particle size (D50) of the resin fine particles in the obtained resin emulsion A was 0.15 μm, the solid content concentration was 31% by weight, and no resin component remained on the wire mesh.

Example 2 and Comparative Examples 1 to 3 (Production of Resin Emulsions B to E)
In Example 1, polyoxyethylene (average number of added moles: 50 mol) lauryl ether, as shown in Table 1, polyoxyethylene (average number of added moles: 26 mol) oleyl ether, polyoxyethylene (average number of added moles: Resin emulsions BE were obtained in the same manner except that 8 mol) lauryl ether, polyoxyethylene (average added mole number: 9 mol) lauryl ether, polyoxyethylene (average added mole number: 13 mol) lauryl ether were used. It was. Table 1 shows the volume median particle size (D50) of the resin fine particles in each obtained fat emulsion.

Example 3 (Production of cyan toner 1)
500 g of resin emulsion A was placed in a 2 liter four-necked flask equipped with a dehydrating tube, a stirrer and a thermocouple, and mixed at room temperature. Next, an aqueous solution in which 25 g of ammonium sulfate (special grade made by Sigma-Aldrich Japan) was dissolved in 237 g of deionized water was added dropwise to the mixture over 10 minutes while stirring with a Kai-type stirrer. Thereafter, the mixed dispersion was heated to 53 ° C. to form aggregated particles, and held at 53 ° C. for 3 hours. An aqueous solution obtained by diluting 16 g of polyoxyethylene (2 mol) aqueous sodium dodecyl ether sulfate (solid content: 28% by weight) with 145 g of deionized water was added. At this time, the volume median particle size (D50) of the aggregated particles was 4.2 μm, and the CV value was 35. After the addition, the temperature was raised to 83 ° C. After holding at 83 ° C. for 1 hour, it was cooled to room temperature. During this time, the toner shape changed from aggregated particles to coalesced particles. The volume-median particle size (D50) of the coalesced particles was 4.2 μm, and the CV value was 32. After cooling, when a 150 mesh (mesh: 105 μm) wire mesh was passed through, 0.3 wt% of coarse particles remained on the wire mesh with respect to the total amount of resin charged.

  A colored resin particle powder was obtained through a suction filtration step, a washing step, and a drying step. 2.5 parts by weight of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., RY50) and 1.0 part by weight of hydrophobic silica (manufactured by Cabot Co., Ltd., Cabo Seal TS720) with respect to 100 parts by weight of the colored resin fine particle powder were added to a Henschel mixer. Externally added to obtain cyan toner 1. The volume-median particle size (D50) of cyan toner 1 was 4.2 μm, and the CV value was 32.

Example 4 and Comparative Examples 4-6
In Example 3, cyan toners 2 to 5 were obtained in the same manner as in Table 1, except that each of the resin emulsions B to E was used instead of the resin emulsion A. Table 1 shows the volume-median particle size (D50) and CV value of each cyan toner.

Further, for each of the cyan toners 1 to 5, the generation rate of coarse particles was determined by the following formula as a weight ratio (wt%) with respect to the total resin amount of charged coarse particles of 105 μm or more. The results are shown in Table 1.
Coarse grain generation rate (%) = [total weight of generated particles of 105 μm or more / total resin weight of preparation] × 100

  According to the production method of the present invention, a toner for electrophotography having a narrow particle size distribution can be produced in a high yield. Therefore, the toner of the present invention is used for electrophotography, electrostatic recording method, electrostatic printing method and the like. It can be suitably used for an electrophotographic toner.

Claims (5)

Toner resin emulsion containing a binder resin, a non-ionic surfactant and sulfonate-type anionic surfactant represented by the following formula (1) comprising polyester.
R ¹ O (CH ₂ CH ₂ O) nH (1)
(In the formula, R ¹ represents an aliphatic hydrocarbon group having 8 to 22 carbon atoms, and n represents an average addition mole number of 25 to 60.)   The resin emulsion for toner according to claim 1, wherein the content of the nonionic surfactant in the resin emulsion is 0.5 to 5 parts by weight with respect to 100 parts by weight of the binder resin. Binder resin comprising a polyester, anionic surfactants of the non-ionic surfactant and sulfonate-type represented by the formula (1) is formed by dispersing in an aqueous medium, according to claim 1 or 2 Resin emulsion for toner.   The resin emulsion for toner according to any one of claims 1 to 3, wherein the emulsified particles in the resin emulsion contain a colorant.   A masterbatch containing a polyester-containing binder resin and a colorant, the polyester-containing binder resin, a nonionic surfactant represented by the formula (1), and a sulfonate-based anionic interface The resin emulsion for toner according to claim 1, wherein the activator is dispersed and emulsified in a basic aqueous medium.