JP4763355B2 - Method for producing toner for developing negatively charged electrostatic latent image - Google Patents

Description

  The present invention relates to a method for producing a toner for developing a negatively chargeable electrostatic latent image used when a latent electrostatic image is made visible in dry electrophotography.

In dry electrophotography, the toner used to make the electrostatic latent image visible is used as a toner containing a binder resin, a colorant, a charge control agent, magnetic powder as required, and other additives. Has been.
As a method for producing toner, a pulverization method for pulverizing a lump containing components constituting the toner has been generally used. However, in recent years, particles can be made fine and uniform, and can easily cope with high resolution. The aggregation method is becoming widespread (for example, see Patent Document 1). In this emulsion aggregation method, a powder charge control agent is first dispersed in water to prepare a charge control agent aqueous dispersion, and then the charge control agent aqueous dispersion, a binder resin emulsion, and a colorant are mixed. To obtain a mixture. Next, an aggregating agent is added to the mixed solution to aggregate the solids contained in the mixed solution, and the obtained solids are collected by filtration, and then washed and dried. The dry solid obtained by this method is used as a toner.

Generally, when a toner is used for visualizing (developing) an electrostatic latent image, its surface is charged by friction. The charge control agent contained in the toner is for controlling the charge of the charge at that time, and a metal-containing complex salt dye or the like is widely used. However, the metal-containing complex salt dye has a problem that the compatibility with the binder resin is low and it is difficult to uniformly adhere to the binder resin. Thus, it has been proposed to use a copolymer containing a sulfonic acid monomer unit (hereinafter referred to as a sulfonic acid copolymer) as a charge control agent (see, for example, Patent Document 2). Since the sulfonic acid copolymer is a resin, it has excellent compatibility with the binder resin.
JP 2001-134005 A Japanese Patent No. 3555562

The sulfonic acid copolymer described in Patent Document 2 is obtained by polymerizing a radical polymerizable monomer and a sulfonic acid monomer by solution polymerization, emulsion polymerization, suspension polymerization or the like, and then dissolving or dispersing in a solvent. It is obtained by recovering the solid matter.
By the way, when the toner is produced by the emulsion aggregation method using the sulfonic acid copolymer as a charge control agent, a solid material of the sulfonic acid copolymer is mixed with water to prepare a charge control agent dispersion. The charge control agent aqueous dispersion, the binder resin emulsion, and the colorant need to be mixed to obtain a mixture. However, since the solid material of the sulfonic acid copolymer is difficult to be redispersed in water, when the emulsion aggregation method described above is applied to the production of the toner, the sulfonic acid copolymer that is a charge control agent is a binder resin. It was difficult to obtain a toner that uniformly adhered to the toner.
The present invention has been made in view of the above circumstances, and even when a sulfonic acid-based copolymer is used as a charge control agent and an emulsion aggregation method is applied to the production of toner, the charge control agent is uniformly applied to the binder resin. It is an object of the present invention to provide a method for producing a negatively chargeable electrostatic latent image developing toner capable of easily producing a negatively charged electrostatic latent image developing toner.

The method for producing a negatively chargeable electrostatic latent image developing toner of the present invention comprises a sulfone containing 99.5 to 80% by mass of a radical polymerizable monomer unit and 0.5 to 20% by mass of a sulfonic acid monomer unit. A negative charge control agent emulsion dispersion (A) which is an emulsion polymerization emulsion of an acid copolymer, a binder resin emulsion dispersion (B) which is an emulsion of a binder resin, and a colorant dispersion in which a colorant is dispersed in water (C) and / or a release agent dispersion liquid (D) in which a release agent is dispersed in water, and mixing to prepare a mixed liquid, and aggregating solids contained in the mixed liquid It possesses a recovery step of recovering Te, in the mixing step, so that the solid content in the negative charge control agent emulsified dispersion (a) becomes 0.5 to 10% by weight of the solids in the contained in the liquid mixture Blended with
The radical polymerizable monomer unit contained in the sulfonic acid copolymer is at least one selected from a styrene monomer unit, a methacrylic acid alkyl ester unit, and an acrylic acid alkyl ester unit. The monomer unit is at least one selected from 2-acrylamido-2-methylpropanesulfonic acid unit, sodium styrenesulfonate unit, sulfoethylacrylic acid unit, sulfoethylmethacrylic acid unit, and sodium sulfoethylmethacrylate unit. It is characterized by.
In the method for producing a negatively chargeable electrostatic latent image developing toner of the present invention, the styrene monomer unit is preferably at least one selected from styrene and α-methylstyrene.

According to the method for producing a negatively chargeable electrostatic latent image developing toner of the present invention, the charge control agent is uniformly adhered to the binder resin even though the toner is produced by an emulsion aggregation method. A toner for developing a latent image can be easily produced.
In the method for producing a negatively chargeable electrostatic latent image developing toner of the present invention, the radical polymerizable monomer unit contained in the sulfonic acid copolymer of the negative charge control agent emulsified dispersion (A) is a styrene monomer. In the case where the sulfonic acid monomer unit is a 2-acrylamido-2-methylpropane sulfonic acid unit, it is easy to polymerize and has a preferred softness. A polymer can be obtained.
In the method for producing a negatively chargeable electrostatic latent image developing toner of the present invention, the content of the radically polymerizable monomer unit in the sulfonic acid copolymer of the negative charge control agent emulsified dispersion (A) is 99. When the content of the sulfonic acid monomer unit is 0.5 to 20% by mass and the content of the sulfonic acid monomer unit is 0.5 to 20% by mass, appropriate chargeability can be imparted to the obtained toner.
Moreover, also when mix | blending so that the solid content in a negative charge control agent emulsion dispersion liquid (A) may be 0.1-15 mass% in the solid substance contained in the said liquid mixture in a mixing process, Appropriate chargeability can be imparted to the resulting toner.

The method for producing a negatively chargeable electrostatic latent image developing toner (hereinafter abbreviated as “toner”) of the present invention comprises a negative charge control agent emulsified dispersion (A), a binder resin emulsified dispersion (B), and a colorant dispersion. (C) and / or mold release agent dispersion (D) are mixed and mixed to prepare a mixed solution, and solids contained in the mixed solution prepared by the mixing step are aggregated and recovered. A recovery step.
Hereinafter, each step will be described.

(Mixing process)
The components (A) to (D) blended in the mixing step will be described.
The negative charge control agent emulsion dispersion (A) is an emulsion polymerization emulsion of a sulfonic acid copolymer containing a radical polymerizable monomer unit and a sulfonic acid monomer unit. Here, the emulsion polymerization emulsion is an emulsion obtained by emulsion polymerization. The sulfonic acid copolymer functions as a negative charge control agent.

Examples of the radical polymerizable monomer include styrene monomers such as styrene and α-methylstyrene, acrylic monomers such as alkyl methacrylate and alkyl acrylate, vinyl acetate, vinyl propionate, and chloride. Examples thereof include vinyl and acrylonitrile.
Examples of the sulfonic acid monomer include sulfoalkyl (meth) acryl such as 2-acrylamido-2-methylpropanesulfonic acid, sodium styrenesulfonate, sulfoethylacrylic acid, sulfoethylmethacrylic acid, and sodium sulfoethylmethacrylate. Examples include acid monomers.
Each of the radical polymerizable monomer and the sulfonic acid monomer may be one kind or a combination of two or more kinds.

  Among the above monomers, the radical polymerizable monomer is a styrene monomer and / or an acrylic acid monomer because it is easy to polymerize and a copolymer having a preferable softness can be obtained. In addition, the sulfonic acid monomer is preferably 2-acrylamido-2-methylpropanesulfonic acid.

  In the sulfonic acid copolymer, the content of the radically polymerizable monomer unit is 99.5 to 80% by mass and the content of the sulfonic acid monomer unit is 0.5 to 20% by mass. Preferably, the content of the radical polymerizable monomer unit is 99 to 85% by mass and the amount of the sulfonic acid monomer unit is 1 to 15% by mass (provided that the radical polymerizable monomer unit and The total with the sulfonic acid monomer units is 100% by mass). When the content of the radical polymerizable monomer unit exceeds 99.5% by mass (when the content of the sulfonic acid monomer unit is less than 0.5% by mass), the resulting toner is not sufficiently charged. Sometimes. Further, even when the content of the radical polymerizable monomer unit is less than 80% by mass (the content of the sulfonic acid monomer unit exceeds 20% by mass), sufficient chargeability can be ensured. become unable.

The negative charge control agent emulsion dispersion (A) is obtained by emulsion polymerization of a radical polymerizable monomer and a sulfonic acid monomer.
Examples of the polymerization initiator used in this case include benzoyl peroxide, t-butyl perbenzoate, dicyclohexyl peroxide, dicumyl peroxide, azobisisobutyronitrile, azobismethylbutyronitrile, azobisdimethylvalero. Nitrile, sodium peroxodisulfate, potassium peroxodisulfate, ammonium peroxodisulfate and the like can be mentioned.
The emulsifier is not particularly limited, and examples thereof include monoalkyl succinate sulfonic acid disodium salt, polyoxyethylene polycyclic phenyl ether sulfate ester salt, alkyl diphenyl ether disulfonate sodium salt, and sodium methacryloyloxyethyl sulfonate.
In the emulsion polymerization, it is preferable to add the radical polymerizable monomer and the sulfonic acid monomer separately. Since the sulfonic acid monomer is easily dissolved in water, the copolymerization with the radical polymerizable monomer can be enhanced by adding it separately.
The sulfonic acid copolymer content in the negative charge control agent emulsion dispersion (A) obtained by this emulsion polymerization is preferably 10 to 40% by mass.

The binder resin emulsified dispersion (B) is an emulsion of a binder resin. Examples of the binder resin include homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and substituted products thereof; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene- Vinyl naphthalene copolymer, styrene acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer Styrene copolymers such as styrene-vinyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride , Fenault Resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester, polyurethane, polyamide, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumaroindene resin And petroleum resins.
Among these, at least one diol component selected from the group consisting of polystyrene, (meth) acrylic acid ester homopolymers or copolymers thereof, bisphenol type diols and glycols, and phthalic acid, isophthalic acid, terphthalic acid Polyesters synthesized from dicarboxylic acids or trimellitic acids such as are preferred.

The binder resin emulsion dispersion (B) is obtained by emulsion polymerization. It can also be obtained by emulsifying and dispersing a binder resin solid obtained by various polymerization methods in a dispersion medium. The emulsifier in the binder resin emulsion dispersion (B) is not particularly limited, and examples thereof include the same emulsifiers as those contained in the negative charge control agent emulsion dispersion (A).
The binder resin content in the binder resin emulsion dispersion (B) is preferably 10 to 50% by mass.

  The colorant dispersion (C) is a liquid in which a colorant is dispersed in water. Specifically, the colorant dispersion (C) may be a suspension dispersion or an emulsification dispersion. However, in order to improve the dispersibility of the colorant, an emulsified dispersion containing an emulsifier (surfactant) is preferable. As the emulsifier, either cationic, anionic, or nonionic is appropriately selected according to the type of the colorant.

Examples of the colorant in the colorant dispersion (C) include carbon black, lamp black, iron black, ultramarine, nigrosine dye, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine 6G, calco oil blue, Chrome yellow, quinacridone, benzidine yellow, rose bengal, triarylmethane dyes, monoazo dyes, disazo dyes and the like can be used alone or in combination.
The colorant content in the colorant dispersion (C) is preferably 5 to 30% by mass.

  The release agent dispersion (D) is a liquid in which the release agent is dispersed in water. Specifically, the release agent dispersion (D) may be a suspension dispersion or an emulsification dispersion. However, in order to improve the dispersibility of the release agent, an emulsified dispersion containing an emulsifier (surfactant) is preferable. As the emulsifier, either cationic, anionic or nonionic is appropriately selected depending on the type of the release agent.

Examples of the release agent in the release agent dispersion (D) include natural waxes such as polyethylene wax, polypropylene wax, higher fatty acid bisamide wax, and carnauba wax.
The release agent content in the release agent dispersion (D) is preferably 5 to 30% by mass.

In the mixing step, each component is preferably blended so that the solid content in the negative charge control agent emulsified dispersion (A) is 0.1 to 15% by mass in the solid contained in the mixed solution. By blending in this way, the solid content of the negative charge control agent emulsified dispersion (A) contained in the obtained toner can be 0.1 to 15% by mass, particularly 0.5 to 10% by mass. it can. If the amount of the solid content of the negative charge control agent emulsified dispersion (A) contained in the toner is outside the above range, the toner cannot have an appropriate chargeability, and the characteristics of an image formed by dry electrophotography Tend to be lower. That is, if the amount of the solid content of the negative charge control agent emulsified dispersion (A) contained in the toner is less than 0.1% by mass, the toner charge rises poorly, the toner scatters a lot, and the toner drops off. Problems may occur. On the other hand, if it exceeds 10% by mass, the hygroscopicity of the toner becomes strong and the change with time in the charge amount becomes large.
In addition, each component here is these components, when mix | blending only (A)-(D) component, and when further mix | blending the other component (E) mentioned later (A) ) To (E).

  Moreover, in a mixing process, you may mix | blend another component (E) other than the said (A)-(D) component. Examples of the other component (E) include a dispersion liquid containing a carrier when a toner is used as a two-component developer. Here, examples of the carrier include resin-coated glass beads and steel balls when the cascade development method is performed, and ferrite, fine iron, or a so-called binder type carrier when the magnetic brush development method is performed. Is mentioned.

(Recovery process)
In the recovery step, the solids contained in the mixed solution may be aggregated by, for example, a salting-out method in which a flocculant is added, heteroaggregation in which emulsion dispersions of different charges are mixed, or a pH that is adjusted to a pH that causes emulsion breakage An adjustment method, a temperature adjustment method for adjusting the temperature to cause emulsification breakage, a spray drying method in which a mixed solution is sprayed into a vacuum dryer, and the like can be applied.
Among these, the salting out method is preferable because it is simple. Examples of the flocculant when applying the salting-out method include aluminum sulfate, calcium nitrate, zinc sulfate, magnesium sulfate, and polyaluminum chloride. The addition amount of the flocculant is preferably 0.05 to 10% by mass, more preferably 0.075 to 2% by mass, based on 100% by mass of the dispersion medium in the mixed liquid.

  The solid obtained by aggregating the mixed solution is preferably washed and dried after recovery. Examples of the cleaning method include a method of rinsing with a large amount of water, and examples of the drying method include a hot air drying method, an infrared irradiation drying method, and a vacuum drying method.

The solid matter recovered by the recovery step is used as toner. The solid material may be used as the toner as it is, but it is preferable to use the solid material after pulverizing and classifying it to select a particle having a predetermined particle size.
The charge amount of the obtained toner is preferably 10 to 40 μC / g, and more preferably 15 to 35 μC / g. When the charge amount of the toner is less than 10 μC / g, it becomes difficult to transfer the toner to a predetermined portion of the recording sheet, and the background portion is easily stained when an image is formed. Further, when the charge amount of the toner exceeds 40 μC / g, the image density tends to decrease.

  As described above, the negative charge control agent dispersion liquid (A) in the toner production method is an emulsion polymerization emulsion of a sulfonic acid copolymer, and is a liquid in which the sulfonic acid copolymer is uniformly dispersed. Therefore, the negative charge control agent emulsion dispersion (A), the binder resin emulsion dispersion (B), the colorant dispersion (C) and / or the release agent dispersion (D) are blended and mixed. Thus, a uniform mixed solution can be prepared. Moreover, since the emulsion polymerization emulsion of a sulfonic acid copolymer is used as it is without being solidified, a mixed solution can be easily prepared. Therefore, a toner in which the charge control agent uniformly adheres to the binder resin can be easily produced by aggregating and collecting the solids contained in the mixed solution. If such toner is used, an image having excellent image quality can be formed.

Hereinafter, the present invention will be specifically described based on examples.
[Preparation Example 1] Preparation of negative charge control agent emulsified dispersion (A-1) In a 3 L flask equipped with a stirrer, a condenser, a thermometer, and a nitrogen introduction tube, 1000 g of pure water and disodium monoalkyl succinate sulfonate as an emulsifier 8 g of a salt (Nippon Emulsifier Newcor 293) and 2 g of a polyoxyethylene polycyclic phenyl ether sulfate salt (Nippon Emulsifier Newcor 707-SF) were charged, and the atmosphere was replaced with nitrogen for 30 minutes.
Next, 2 g of potassium peroxodisulfate (KPS) was charged into the flask and dissolved by stirring. Thereafter, the temperature was raised to 70 ° C. under introduction of nitrogen, and a monomer mixture of 280 g of styrene and 80 g of 2-ethylhexyl acrylate (2-EHA) and 40 g of 2-acrylamido-2-methylpropanesulfonic acid (AAPS) were purified. An aqueous solution dissolved in 600 g of water was separately dropped into the flask over 3 hours. Thereafter, polymerization was continued at 80 ° C. for 3 hours, and for the purpose of reducing the residual monomer, 0.3 g of KPS was newly added, the temperature was raised to 85 ° C., and the mixture was reacted for 2 hours to give a negative charge control agent emulsion dispersion (A- 1) was obtained.

[Preparation Example 2] Preparation of negative charge control agent emulsified dispersion (A-2) Preparation Example 1 except that 80 g of acrylic acid-n-butyl was mixed instead of 80 g of 2-ethylhexyl acrylate (2-EHA) In the same manner as above, a negative charge control agent emulsified dispersion (A-2) was obtained.

[Preparation Example 3] Preparation of negative charge control agent emulsified dispersion (A-3) 8 g of sodium alkyldiphenyl ether disulfonate (New Coal 271A manufactured by Nippon Emulsifier) was mixed instead of 8 g of monoalkyl succinate sulfonic acid disodium salt. Except for the above, a negative charge control agent emulsified dispersion (A-3) was obtained in the same manner as in Preparation Example 1.

[Preparation Example 4] Preparation of emulsified dispersion of negative charge control agent (A-4) 1 g of sodium methacryloyloxyethyl sulfonate (Antox MS-2N manufactured by Nippon Emulsifier) instead of 8 g of monoalkyl succinate sulfonic acid disodium salt And a negative charge control agent emulsified dispersion (A-4) in the same manner as in Preparation Example 1 except that the amount of polyoxyethylene polycyclic phenyl ether sulfate ester (Nippon Emulsifier Newcor 707-SF) was changed to 3 g. )

[Preparation Example 5] Preparation of negative charge control agent emulsified dispersion (A-5) Same as Preparation Example 1, except that the amount of styrene was changed to 318 g and the amount of 2-acrylamido-2-methylpropanesulfonic acid was changed to 1 g. Thus, a negative charge control agent emulsified dispersion (A-5) was obtained.

[Preparation Example 6] Preparation of negative charge control agent emulsified dispersion (A-6) Same as Preparation Example 1, except that the amount of styrene was changed to 220 g and the amount of 2-acrylamido-2-methylpropanesulfonic acid was changed to 100 g. Thus, a negative charge control agent emulsified dispersion (A-6) was obtained.

[Preparation Example 7] Preparation of negative charge control agent emulsified dispersion (A-7) 10 g of salicylic acid metal complex (Bontron E-84 manufactured by Orient Chemical Industries), 5 g of nonionic surfactant (Nonipol 400 manufactured by Sanyo Chemical Industries) In addition, 190 g of ion-exchanged water was mixed and dispersed for 20 minutes using a homogenizer (Ultra Turrax T25 manufactured by IKA) to obtain a negative charge control agent emulsified dispersion (A-7).

[Preparation Example 8] Preparation of Binder Resin Emulsion Dispersion (B-1) Into a 3 L flask equipped with a stirrer, condenser, thermometer and nitrogen introduction tube, 930 g of pure water and sodium alkyldiphenyl ether disulfonate as an emulsifier (New from Japan Emulsifier) Cole 271A) was charged with 10 g, and the atmosphere was replaced with nitrogen for 30 minutes.
Next, 2 g of potassium peroxodisulfate (KPS) was charged into the flask and dissolved by stirring. Thereafter, the temperature was raised to 80 ° C. under nitrogen introduction, and a monomer mixture of 280 g of styrene and 120 g of acrylic acid-n-butyl was charged and stirred. Thereafter, the inside of the flask was heated to 80 ° C. and polymerized for 3 hours. Thereafter, for the purpose of reducing the residual monomer, 0.3 g of KPS was newly added, heated to 85 ° C., and reacted for 2 hours to obtain a binder resin emulsion dispersion (B-1).

[Preparation Example 9] Preparation of Binder Resin Emulsion Dispersion (B-2) Binder Resin Emulsion Dispersion as in Preparation Example 8 except that a monomer mixture further containing 8 g of acrylic acid was used. (B-2) was obtained.

[Preparation Example 10] Preparation of Binder Resin Emulsified Dispersion (B-3) In a 3 L flask equipped with a stirrer, condenser, thermometer and nitrogen introduction tube, 930 g of pure water and sodium alkyldiphenyl ether disulfonate as an emulsifier (New from Japan Emulsifier) Cole 271A) was charged with 10 g, and the atmosphere was replaced with nitrogen for 30 minutes.
Next, 2 g of potassium peroxodisulfate (KPS) was charged into the flask and dissolved by stirring. Thereafter, the temperature was raised to 80 ° C. under introduction of nitrogen, and a mixed solution of 340 g of styrene, 60 g of n-butyl acrylate and 12 g of n-dodecyl mercaptan (Kao thiocalcol 20) was charged and stirred. Thereafter, the flask was heated to 80 ° C. and polymerized for 5 hours. Thereafter, for the purpose of reducing the residual monomer, 0.3 g of KPS is newly added, the temperature is raised to 85 ° C., the reaction is performed for 2 hours, and further 0.3 g of KPS is added, the temperature is raised to 85 ° C., and the reaction is performed for 2 hours. Thus, a binder resin emulsion dispersion (B-3) was obtained.

[Preparation Example 11] Preparation of Binder Resin Emulsified Dispersion (B-4) Binder Resin Emulsion Dispersion (B-4) was prepared in the same manner as Preparation Example 10 except that the mixture was further mixed with 8 g of methacrylic acid. -4) was obtained.

[Preparation Example 12] Preparation of Colorant Dispersion (C-1) 50 g of carbon black (NIPEX 150 manufactured by Degussa), 5 g of nonionic surfactant (Nonipol 400 manufactured by Sanyo Chemical Industries), and 200 g of ion-exchanged water were mixed together. (IKA Ultra Turrax T25) was used for dispersion for 20 minutes to obtain a colorant dispersion (C-1).

[Preparation Example 13] Preparation of Colorant Dispersion (C-2) Copper phthalocyanine pigment (FASTOGEN BLUE TGRC.IB 15: 3, manufactured by Dainippon Ink and Chemicals, Inc.) instead of 50 g of carbon black was mixed. A colorant dispersion (C-2) was obtained in the same manner as in Preparation Example 12.

[Preparation Example 14] Preparation of mold release agent dispersion (D-1) 50 g of paraffin wax (HNP0190 manufactured by Nippon Seiwa), 5 g of cationic surfactant (Sanisol B50 manufactured by Kao) and 200 g of ion-exchanged water were mixed. After heating to ° C., a release agent dispersion (D-1) was obtained by dispersing for 20 minutes using a homogenizer (Ultra Turrax T25 manufactured by IKA).

(Production Examples 1-12)
In a 1 L flask, the negative charge control agent emulsified dispersion (A-1 to 7), the binder resin emulsified dispersion (B-1 to 4), and the colorant dispersion (C-1 and 2) obtained as described above. ), The release agent dispersion (D-1) was blended in the amounts shown in Tables 1 and 2, and the mixture was heated to 45 ° C. and mixed with stirring.
Next, after adding 30 g of a calcium nitrate aqueous solution as a 10 mass% flocculant to the flask over 2 hours, the temperature was raised to 95 ° C. and kept at that temperature for 2 hours. Then, after cooling to room temperature and washing with 500 g of pure water, the solid matter was recovered by suction filtration with a Nutsche (filter paper: FILTER PAPER 5C manufactured by ADVANTEC), and then the recovered solid matter was blown and dried at 45 ° C. for 20 hours. .
Next, the dried solid was pulverized by a pulverizer (Milcer 600 manufactured by Iwatani Corporation) and then classified by a classifier (Nippon Pneumatic Industrial MDS) to obtain a toner having an average particle diameter of 7 μm.

For the toners of Production Examples 1 to 12, the charge amount was measured by the following method.
First, 0.5% by mass of Aerosil R972 (Nippon Aerosil silica particles) was added to 100% by mass of the toner and stirred uniformly. Next, 100 parts by mass of this silica-coated toner was mixed with 3 parts by mass of a carrier (F-150 manufactured by Powdertech Co., Ltd.), and then frictionally charged in an atmosphere of 20 ° C. and 65% RH for 60 minutes. Then, the charge amount was measured with a blow-off powder charge amount measuring device (TB-203) manufactured by Toshiba Chemical. The results are shown in Tables 1 and 2.

A negative charge control agent emulsion dispersion (A) which is an emulsion polymerization emulsion of a sulfonic acid copolymer, a binder resin emulsion dispersion (B), a colorant dispersion (C), and a release agent dispersion (D) In the toners of Production Examples 1 to 11 obtained by blending with the toner, the sulfonic acid copolymer was uniformly attached to the styrene-acrylic copolymer. Moreover, the amount of the negative charge control agent emulsifier dispersion (A) is within a specific range, and the content of the radical polymerizable monomer unit and the sulfonic acid monomer unit in the sulfonic acid copolymer is specific. The toners of Production Examples 1 to 7, which are in the range, had appropriate chargeability. However, the toner of Preparation Example 8 with a small amount of the negative charge control agent emulsifier dispersion (A) has a low charging property, and the toner of Preparation Example 9 with a large amount of the negative charge control agent emulsifier dispersion (A) is charged. Sex was too high. Further, Production Examples 10 and 11 in which the content of the radical polymerizable monomer unit and the sulfonic acid monomer unit in the sulfonic acid copolymer in the negative charge control agent emulsified dispersion (A) are not within a specific range. The toner of this example also had low chargeability.
In contrast, in the toner of Production Example 12 using the metal-containing complex salt dye as the negative charge control agent emulsified dispersion (A), the negative charge control agent was not uniformly adhered to the binder resin, The nature was also low.

Further, the redispersibility of the sulfonic acid copolymer recovered from the negative charge control agent emulsified dispersion (A-1) in water was examined as follows.
First, the negative charge control agent emulsified dispersion (A-1) was dried in a vacuum dryer at 50 ° C. until the water content became 1% or less to obtain a sulfonic acid copolymer solid. Next, 5 g of the obtained sulfonic acid copolymer solid was added to an emulsifier aqueous solution in which a nonionic surfactant (Nonipol 400 manufactured by Sanyo Chemical Industries) was dissolved in ion-exchanged water 190. And it was made to disperse | distribute for 20 minutes using the homogenizer (The Ultra-Turrax T25 made from IKA). As a result, the sulfonic acid copolymer was not dispersed in water, and immediately settled when stirring of the homogenizer was stopped. That is, the solid material of the sulfonic acid copolymer is difficult to redisperse in water. Therefore, when a solid material of a sulfonic acid copolymer is used as the charge control agent and the emulsion aggregation method is applied to the production of the toner, it is difficult to obtain a toner in which the charge control agent uniformly adheres to the binder resin. is there. Therefore, the present invention is extremely effective when a sulfonic acid copolymer is used as the charge control agent and the emulsion aggregation method is applied to the production of the toner.

Claims (2)

Emulsion dispersion of negative charge control agent which is an emulsion polymerization emulsion of sulfonic acid copolymer containing 99.5 to 80% by mass of radical polymerizable monomer unit and 0.5 to 20% by mass of sulfonic acid monomer unit (A), binder resin emulsion dispersion (B) which is an emulsion of binder resin, colorant dispersion (C) in which a colorant is dispersed in water and / or release agent dispersion in which a release agent is dispersed in water A mixing step of blending and mixing the liquid (D) to prepare a mixed liquid;
Possess a recovery step of recovering by aggregating the solids contained in the mixture,
In the mixing step, the solid content in the negative charge control agent emulsified dispersion (A) is blended so as to be 0.5 to 10% by mass in the solid contained in the mixed solution,
The radical polymerizable monomer unit contained in the sulfonic acid copolymer is at least one selected from a styrene monomer unit, a methacrylic acid alkyl ester unit, and an acrylic acid alkyl ester unit. The monomer unit is at least one selected from 2-acrylamido-2-methylpropanesulfonic acid unit, sodium styrenesulfonate unit, sulfoethylacrylic acid unit, sulfoethylmethacrylic acid unit, and sodium sulfoethylmethacrylate unit. And a method for producing a negatively chargeable electrostatic latent image developing toner.   The method for producing a negatively chargeable electrostatic latent image developing toner according to claim 1, wherein the styrene monomer unit is at least one selected from styrene and α-methylstyrene.