JP2017067925A - Method for manufacturing negative charge type toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently manufacturing a negative charge type toner which has carbon black as a colorant adequately dispersed therein, has high chargeability, is excellent in transfer efficiency and low-temperature fixability, prevents generation of voids, and can obtain an image having sufficient image density.SOLUTION: There is provided a method for manufacturing a negative charge type toner which includes: a step of dispersing at least a binder resin, carbon black, wax and a charge control agent in an organic solvent to obtain an organic solvent composition, suspending the organic solvent composition in an aqueous dispersion medium containing a dispersion stabilizer to form droplet of the organic solvent composition; a step of distilling the organic solvent from the droplet to obtain suspension of coloring resin particles, where the organic solvent composition further contains an aluminum coupling agent, and the organic solvent composition contains a sulfonic acid group-containing copolymer as the charge control agent which is obtained by copolymerization of vinyl aromatic hydrocarbon, (meth)acrylamide and sulfonic acid group-containing (meth)acrylamide and where a copolymerization ratio of a monomer unit of the sulfonic acid group-containing (meth)acrylamide is 0.8-6.0 mass%.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a negatively chargeable toner that can be used for development of an image forming apparatus using electrophotography such as a copying machine, a facsimile machine, and a printer.

  In recent years, there has been an increasing need for colorization of image forming apparatuses such as multifunction peripherals, facsimiles, and printers using electrophotography. In color printing, since it is required to reproduce a high-resolution and clear color tone like a photograph, a color toner that can cope with it is demanded. For such toners, from the viewpoint of environmental stability from the viewpoint of preventing image quality deterioration due to environmental changes such as temperature and humidity, printing durability from the viewpoint of reducing printing costs, and power consumption. Various printing performances such as low-temperature fixability are required.

In order to meet the above requirements, a spherical toner having a small particle size that can achieve both good transferability and dot reproducibility is suitable, and a wet method has been proposed as a manufacturing method thereof. The conventional pulverization method has a low yield and consumes a lot of energy, especially when producing a toner having a small particle diameter, whereas the wet method has a high yield and does not require a pulverization step. The energy consumption is low, and a spherical toner can be easily manufactured.
In addition, when obtaining colored resin particles by a wet method, it is possible to form spherical colored resin particles with a small particle size and a sharper particle size distribution than the conventional pulverization method at the stage of forming the particles. Has great advantages.

  However, in recent years, with the further increase in the required level for high resolution and high image quality, it has been pointed out that even wet type toners must be solved.

  When the toner is produced by the wet method as described above, it is difficult to uniformly disperse the pigment as the colorant in the toner, and there is a problem that the density of the formed image is lowered. In addition, as a countermeasure to this problem, if the amount of pigment added to the toner is increased in order to obtain a sufficient image density, the pigment aggregates in the toner and the charging performance of the toner becomes unstable. Problems such as voids and toner scattering occur.

  As a method for solving the above problem, Patent Document 1 discloses that when a toner is produced by a wet method, if a pigment that has been previously coupled with a coupling agent is used, the dispersibility of the colorant is improved and the toner is charged. It has been disclosed that the property is stabilized, an image having a sufficient image density is obtained, and occurrence of voids and toner scattering are prevented.

JP 2005-165155 A

However, when Patent Document 1 is examined, in paragraph [0006], as an example of a wet method, a suspension polymerization method, an emulsion dispersion method (referred to as “dissolution suspension method” in this specification), an emulsion polymerization aggregation method, and the like. Although described, in the examples, the toner is produced only by the emulsion polymerization aggregation method. Here, when the method described in Patent Document 1 is carried out by the dissolution suspension method using carbon black (CB) as a colorant, the dispersibility of the carbon black in the toner becomes insufficient, and the void is lost. Etc. occur.
In the dissolution suspension method, first, a binder resin, a colorant, and other additives as required are mixed with an organic solvent to obtain an organic solvent composition, which contains a dispersion stabilizer. Disperse in an aqueous dispersion medium. Next, droplets of the organic solvent composition are formed by applying a high share to the aqueous dispersion medium in which the organic solvent composition is dispersed using an in-line type emulsifying disperser or the like. Thereafter, the organic solvent is distilled away from the droplets to obtain a suspension of colored resin particles, and colored resin particles are obtained through filtration, washing and drying with a filter medium.
The dispersion of the colorant is an oil phase in the dissolution suspension method, whereas the difference that it is an aqueous phase in the emulsion polymerization aggregation method described as an example in Patent Document 1 greatly affects the dispersibility of carbon black. Is thought to contribute to this problem.
In general, when carbon black is used as a colorant, the electrical resistance of the toner is reduced. Therefore, it is necessary to use a highly chargeable charge control agent. However, a negatively chargeable toner using a highly chargeable charge control agent is required. In the case of obtaining the carbon black, it is considered that the cause is that the carbon black easily aggregates.

  An object of the present invention is to solve the above-mentioned problems, and carbon black as a colorant is well dispersed, has high chargeability, excellent transfer efficiency, no occurrence of white spots, and an image having a sufficient image density. It is an object to provide an efficient method for producing a negatively chargeable toner that can be obtained.

  As a result of intensive studies to solve the above problems, the present inventor uses an organic solvent composition containing an aluminum coupling agent and a specific charge control agent in addition to the binder resin, carbon black, and wax. It has been found that the above problems can be solved.

  That is, according to the present invention, an organic solvent composition is obtained by dispersing at least a binder resin, carbon black, wax, and a charge control agent in an organic solvent, and the organic solvent composition is used as a dispersion stabilizer. A step of forming droplets of the organic solvent composition by suspending in the aqueous dispersion medium to be contained, and a step of distilling off the organic solvent from the droplets to obtain a suspension of colored resin particles. A method for producing a chargeable toner, wherein the organic solvent composition further contains an aluminum coupling agent, and the organic solvent composition comprises a vinyl aromatic hydrocarbon and (meth) acrylate as the charge control agent. And a sulfonic acid group-containing (meth) acrylamide copolymer, and the copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide monomer unit is 0.8 to 6.0% by mass. Characterized in that it comprises a sulfonic acid group-containing copolymer, method for producing a negatively chargeable toner is provided.

  In the present invention, the wax preferably contains an ester wax.

  In the present invention, the wax preferably contains a hydrocarbon wax.

  In this invention, it is preferable that the copolymerization ratio of the sulfonic acid group containing (meth) acrylamide monomer unit of the said sulfonic acid group containing copolymer is 1.0-4.5 mass%.

  In the present invention, the sulfonic acid group-containing copolymer preferably has a weight average molecular weight of 5,000 to 30,000.

  In the present invention, the organic solvent composition preferably contains 0.1 to 8.0 parts by mass of the charge control agent with respect to 100 parts by mass of the binder resin.

  According to the production method of the present invention as described above, by using an organic solvent composition containing an aluminum coupling agent and a specific sulfonic acid group-containing copolymer, carbon black as a colorant is well dispersed. The present invention provides an efficient method for producing a negatively chargeable toner having high chargeability, excellent transfer efficiency and low-temperature fixability, no occurrence of white spots, and an image having a sufficient image density.

  In the method for producing a negatively chargeable toner of the present invention, an organic solvent composition is obtained by dispersing at least a binder resin, carbon black, wax, and a charge control agent in an organic solvent, and the organic solvent composition is dispersed. A step of forming droplets of the organic solvent composition by suspending in an aqueous dispersion medium containing a stabilizer, and a step of obtaining a suspension of colored resin particles by distilling off the organic solvent from the droplets The organic solvent composition further contains an aluminum coupling agent, and the organic solvent composition contains vinyl aromatic hydrocarbon as the charge control agent. A copolymerization ratio of (meth) acrylate and sulfonic acid group-containing (meth) acrylamide and a copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide monomer unit is 0.8 to 6 Characterized in that it comprises a sulfonic acid group-containing copolymer is from 0%.

  In the present invention, the expression “(meth) acrylate” is a generic term for both acrylate and methacrylate. In the present invention, the expression “(meth) acrylamide” is a generic term for both acrylamide and methacrylamide.

Hereinafter, a method for producing the negatively chargeable toner of the present invention (hereinafter sometimes simply referred to as “toner”) will be described.
In the toner production method of the present invention, an organic solvent composition containing at least a binder resin, carbon black, wax, an aluminum coupling agent, and a charge control agent is suspended in an aqueous dispersion medium containing a dispersion stabilizer. A step of forming droplets of the organic solvent composition by turbidity, and a step of distilling off the organic solvent from the droplets to obtain a suspension of colored resin particles.
Hereinafter, a step of forming droplets of the organic solvent composition, a step of obtaining a suspension of the colored resin particles, a step of producing a toner using the colored resin particles, and a toner obtained by the production method of the present invention Will be described in order.

1. Step of forming droplets of organic solvent composition The organic solvent composition used in the production method of the present invention is prepared by the following process.

(1) Preparation of organic solvent composition An organic solvent composition is obtained by dispersing a binder resin, carbon black, wax, an aluminum coupling agent, and a charge control agent in an organic solvent.
In order to obtain an organic solvent composition by dissolving or dispersing the binder resin or the like in an organic solvent, a disperser is appropriately used. Dispersers used for stirring the organic solvent composition include media-type dispersers and in-line type emulsifiers (trade name: Milder, manufactured by Taiheiyo Kiko Co., Ltd.), high-speed emulsifiers / dispersers (special machine industries, trade name: TK homomixer MARK II type) and the like, and a media type disperser is preferable.
In the media type dispersing machine, a rotor is rotatably disposed in a stator, a medium particle is filled in a space formed by the stator and the rotor, and the media particle is moved by the rotating rotor. Media-type dispersers include a horizontal cylinder type, a vertical cylinder type, and an inverted triangle type, depending on the shape and placement of the stator. Specific examples of media-type dispersers include Attritor (product name, manufactured by Mitsui Miike), Mighty Mill (product name, manufactured by Inoue Seisakusho), Diamond Fine Mill (product name, manufactured by Mitsubishi Heavy Industries), and Dino Mill (product name). , Shinmaru Enterprises Co., Ltd.), Picomill (product name, manufactured by Asada Tekko Co., Ltd.), Star Mill (product name, manufactured by Ashizawa Finetech Co., Ltd.), Apex Mill (product name, manufactured by Kotobuki Giken Co., Ltd.), and the like.

  The binder resin used in the present invention may be obtained by any polymerization technique such as emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization and the like. The state of the resin when dissolving the resin in the solvent is not particularly limited as long as it is well dissolved in the solvent, and various states such as those dried after polymerization, those in a slurry state, those in a solution state are applicable. it can. Those that have been polymerized in an aqueous medium are preferably added to the solvent after some degree of dehydration in order to dissolve them well in the solvent. Examples of the binder resin include polyamide resin, polyurethane resin, epoxy resin, polyester resin, polyolefin resin, polyacrylate resin, styrene resin, and styrene resin because it can be easily dispersed and stabilized in a solvent. Based resins are preferred. The styrene resin may be a styrene homopolymer or a copolymer of another vinyl monomer and styrene. Monomers for forming a copolymer with styrene include olefins, vinyl halides, vinyl esters, unsaturated carboxylic acids (esterified products thereof), glycidyl compounds, vinyl ethers, vinyl ketones, N-vinyl compounds, dienes, Nitriles, compounds containing two or more vinyl groups, and the like.

In the production method of the present invention, carbon black is used as a colorant.
As described above, when carbon black is used as the colorant, the electrical resistance of the toner is reduced, so that the print density is reduced. In order to increase the printing density, it is conceivable to increase the amount of carbon black added. However, increasing the amount added causes a problem that the charge amount of the resulting toner decreases. In order to increase the charge amount, it is conceivable to use a highly chargeable charge control agent. However, when a negatively chargeable toner is obtained using a highly chargeable charge control agent, there is a problem that carbon black aggregates. . Due to such problems, it has been difficult to manufacture toner satisfying a high level in a well-balanced manner with many requirements by the conventional manufacturing method.
In the present invention, the content of carbon black in the organic solvent composition is preferably 1 to 15 parts by mass with respect to 100 parts by mass of the binder resin. If the carbon black content is less than 1 part by mass with respect to 100 parts by mass of the binder resin, the print density of the manufactured toner may be reduced, and if it exceeds 15 parts by mass, There is a risk that the electrical resistance will decrease.
The content of carbon black in the organic solvent composition is more preferably 5 to 13 parts by mass, and further preferably 6 to 11 parts by mass with respect to 100 parts by mass of the binder resin.

The number average primary particle diameter of carbon black used in the production method of the present invention is preferably 10 to 100 nm. If the number average primary particle size of the carbon black is less than 10 nm, the dispersibility of the toner after production may be lowered, and if it exceeds 100 nm, the color development property of the toner after production may be lowered.
The number average primary particle size of the carbon black used in the production method of the present invention is more preferably 15 to 90 nm, and further preferably 20 to 70 nm.
The number average primary particle diameter of carbon black can be measured using, for example, a particle size analyzer (manufactured by Shimadzu Corporation, trade name “SALD”).

DBP oil absorption of the carbon black used in the production method of the present invention is preferably 10 to 100 cm ^3/100 g. When the DBP oil absorption of carbon black is less than 10 cm ^3/100 g, there is a possibility that the dispersibility of the toner after production is ^decreased, and when it is more than 100 cm 3/100 g, is a possibility that the electric resistance of the toner after production is reduced is there.
DBP oil absorption of the carbon black used in the production method of the present invention is more preferably 20~90cm ³ / 100g, further preferably 30~80cm ³ / 100g.
The DBP oil absorption of carbon black can be measured based on JIS K6221.

A commercially available carbon black can also be used.
Examples of the carbon black that meets the above conditions of the number average primary particle size and DBP oil absorption are carbon black (manufactured by Mitsubishi Chemical Corporation, product name: # 25B, number average primary particle size 40 nm, DBP oil absorption 64 cm ³ / 100g), carbon black (Mitsubishi Chemical Co., Ltd., product name: # 44B, the number average primary particle diameter of 24nm, DBP oil absorption of 78cm ³ / 100g), carbon black (Cabot Corporation, trade name Legal 99R; pH9, the number average The primary particle diameter of 38 nm, DBP oil absorption of 65cm ³ / 100g), carbon black (Mitsubishi Chemical Corporation, # 45; pH8, number-average primary particle size 24 nm, DBP oil absorption of 53cm ³ / 100g), carbon black (Degussa Corp. Product name Printex G; pH 9, number average primary particle size 1 nm, DBP oil absorption of 96cm ^3/100 g), carbon black (Cabot Corporation, trade name MONARCH 120; pH 8, number average primary particle diameter 75 nm, DBP oil absorption of 72cm ^3/100 g), carbon black (Mitsubishi Chemical Corporation, trade name # 5; pH 8, number average primary particle diameter 85 nm, DBP oil absorption of 71cm ^3/100 g), carbon black (Mitsubishi Chemical Corporation, trade name # 2300; pH 8, number average primary particle diameter 15 nm, DBP oil absorption 65cm ³ / 100g), and the like.
These carbon blacks may be used alone or in combination of two or more.

  The wax used in the present invention refers to an additive that enhances low-temperature fixability. In the present invention, the wax preferably contains an ester wax and / or a hydrocarbon wax, and more preferably contains an ester wax and a hydrocarbon wax. By using these waxes, the balance between low-temperature fixability and heat-resistant storage stability can be made suitable.

  The ester wax suitably used in the present invention is more preferably a polyfunctional ester wax, for example, pentaerythritol ester compounds such as pentaerythritol tetrapalmitate, pentaerythritol tetrabehenate, pentaerythritol tetrastearate; hexaglycerin Tetrabehenate tetrapalmitate, hexaglycerin octabehenate, pentaglycerin heptabehenate, tetraglycerin hexabehenate, triglycerin pentabehenate, diglycerin tetrabehenate, glycerin tribehenate, etc. Glycerin ester compounds; dipentaerythritol ester compounds such as dipentaerythritol hexamyristate and dipentaerythritol hexapalmitate;

  The acid value of the ester wax is preferably 1.0 mgKOH / g or less, more preferably 0.6 mgKOH / g or less, and further preferably 0.3 mgKOH / g or less. When the acid value is larger than 1.0 mgKOH / g, the storage stability may be deteriorated. The acid value of the ester wax is a value measured according to JIS K0070, which is a standard oil analysis method established by the Japan Industrial Standards Committee (JISC).

The ester wax has a hydroxyl value of preferably 10 mgKOH / g or less, more preferably 6 mgKOH / g or less, and even more preferably 3 mgKOH / g or less. When the hydroxyl value is larger than 10 mgKOH / g, the storage stability may be deteriorated. The hydroxyl value of the ester wax is a value measured according to JIS K0070, which is a standard oil analysis method established by the Japan Industrial Standards Committee (JISC).
It is more preferable that the ester wax satisfies both the acid value and hydroxyl value conditions described above.

The ester wax is preferably used in an amount of 2 to 10 parts by mass, more preferably 2 to 7 parts by mass, with respect to 100 parts by mass of the binder resin.
The melting point of the ester wax is usually 50 to 90 ° C, preferably 60 to 85 ° C, more preferably 65 to 75 ° C.

As the hydrocarbon wax, it is preferable to use a hydrocarbon that forms a molecular chain only with a C—H bond and a C—C bond. Examples of the hydrocarbon include microcrystalline wax, paraffin wax, polyethylene wax, polypropylene wax, and Fischer-Tropsch wax. Among these, a microcrystalline wax having a low melting point is preferable from the viewpoint of a small amount of volatile components at the time of fixing and an improvement in low-temperature fixability.
The hydrocarbon wax preferably has a melt viscosity at 140 ° C. of 6 to 15 [mPa · S].
Furthermore, it is preferable that the weight loss at 165 ° C. of the hydrocarbon wax is 10% by mass or less. Thereby, the volatile content at the time of fixing can be reduced. The weight loss of the hydrocarbon wax at 165 ° C. is more preferably 3% by mass or less.

  The melting point of the hydrocarbon wax is preferably a low melting point from the viewpoint of improving the low-temperature fixability, preferably having a melting point of 50 ° C. to 90 ° C., preferably 55 ° C. to 82 ° C. More preferably, the thing of 60-78 degreeC is still more preferable. If the melting point is less than 50 ° C., the hydrocarbon wax may adversely affect the heat resistant storage stability, and if it exceeds 90 ° C., cold offset may easily occur during fixing at a low temperature. Furthermore, when the hydrocarbon wax is dispersed in the liquid, the hydrocarbon wax is once melted in the liquid and cooled to create a dispersion. However, when the melting point of the hydrocarbon wax exceeds 90 ° C. The boiling point of the liquid in which the hydrocarbon wax is dispersed needs to be higher than 90 ° C. When such a solvent is used, when the solvent is removed, the temperature may become higher than the glass transition point of the toner, and the toner may cause blocking. As a means for lowering the melting point of the hydrocarbon wax, it is common to lower the molecular weight of the hydrocarbon wax. However, if the molecular weight of the hydrocarbon wax is simply lowered, the volatile content increases. The microcrystalline wax is preferable from the viewpoint of lowering the melting point of the hydrocarbon wax and reducing the volatile content at the time of fixing the hydrocarbon wax.

  In addition, hydrocarbon waxes that satisfy such requirements may deteriorate the separation between the roller and the paper at the time of fixing to the paper. For this reason, it is necessary to give the toner a certain amount of gel. The separation of the roller and the paper at the time of fixing can be improved by the gel content in the toner. The gel content in the toner can be measured as a content insoluble in tetrahydrofuran (THF). The THF insoluble content is preferably 5% by mass to 25% by mass. When the THF-insoluble content is 5% by mass or more, the deterioration of separation at the time of fixing is suppressed. Moreover, if it is 25 mass% or less, the deterioration of low temperature fixability will be suppressed.

  The melt viscosity of the hydrocarbon wax is measured by a Brookfield method using a B-type viscometer. In the measurement, the measurement sample is heated from room temperature, and a value at a temperature equal to or higher than the melting temperature of the sample and at a temperature of 140 ° C. approximate to the actual fixing temperature is preferable.

In addition to the above wax, for example, a natural wax such as jojoba; a mineral wax such as ozokerite;
As the wax, one or two or more kinds of waxes described above can be used in appropriate combination.
The total content of the wax is preferably 1 to 25 parts by mass and more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the binder resin.

  In the toner of the present invention, the total amount of wax in the toner particles showing the dispersion state of the wax can be defined by the following measurement. The total amount of wax in the toner particles is obtained by a DSC (Differential Scanning Calorimeter) method. Each of the toner sample and the single wax sample is measured by the following measuring device and conditions, and each is obtained from the ratio of the endothermic amounts of the waxes obtained.

-Measuring device: DSC device (DSC60: manufactured by Shimadzu Corporation)
-Sample amount: about 5mg
-Temperature rising temperature: 10 ° C / min
Measurement range: room temperature to 150 ° C
・ Measurement environment: In nitrogen gas atmosphere

The total amount of wax was calculated by the following formula (1).
Total amount of wax (% by mass) = (Endothermic amount of wax of toner sample (J / g)) × 100) / (Endothermic amount of single wax (J / g)) Formula (1)

As the charge control agent, a sulfonic acid group-containing copolymer obtained by copolymerizing vinyl aromatic hydrocarbon, (meth) acrylate and sulfonic acid group-containing (meth) acrylamide is used. This sulfonic acid group-containing copolymer is sometimes referred to as a charge control resin. The sulfonic acid group-containing copolymer is colorless enough to obtain a color toner. By copolymerizing a sulfonic acid group-containing (meth) acrylamide, a sulfonic acid group is contained in the copolymer, whereby the sulfonic acid group-containing copolymer is used as a negatively chargeable charge control agent. Can do. The copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide monomer unit in the sulfonic acid group-containing copolymer must be in the range of 0.8 to 6.0% by mass, preferably 1 It is in the range of 0.0 to 4.5% by mass, more preferably in the range of 1.0 to 3.5% by mass, and still more preferably in the range of 1.5 to 3.0% by mass. If the copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide is less than 0.8% by mass, the effect of imparting negative chargeability is small, and conversely, if it exceeds 6.0% by mass, the droplets of the organic solvent composition The dispersion stability is lowered, and a polymerized toner having a uniform particle size cannot be obtained. In addition, the environmental stability of image quality deteriorates even if the copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide is too small or too large.
In the present invention, the sulfonic acid group includes a salt thereof (sulfonic acid group).

The copolymerization ratio (mass%) of the sulfonic acid group-containing (meth) acrylamide monomer unit in the sulfonic acid group-containing copolymer is the so-called preparation when the sulfonic acid group-containing copolymer is synthesized and used. The amount ratio, that is, the value of the sulfonic acid group-containing (meth) acrylamide used can be divided by the total mass of the vinyl aromatic hydrocarbon, (meth) acrylate and sulfonic acid group-containing (meth) acrylamide. .
In addition, when the ready-made sulfonic acid group-containing copolymer is used and the composition of the charged amount is unknown, the sulfonic acid group-containing copolymer is analyzed by elemental analysis such as fluorescent X-ray analysis (XRF). From the result, the copolymerization ratio (% by mass) of the sulfonic acid group-containing (meth) acrylamide monomer unit can be calculated.

  By copolymerizing vinyl aromatic hydrocarbons, a sulfonic acid group-containing copolymer can be obtained stably. By adjusting the copolymerization ratio between the vinyl aromatic hydrocarbon and (meth) acrylate, the glass transition temperature (Tg) of the sulfonic acid group-containing copolymer can be controlled within a desired range, thereby improving the heat resistance. The fixing temperature can be relatively lowered without impairing the storage stability. Also, by using a combination of vinyl aromatic hydrocarbon and (meth) acrylate, the compatibility between the sulfonic acid group-containing copolymer and the resin component of the toner can be improved. Can be a homogeneous toner. The copolymerization ratio (by mass) of the vinyl aromatic hydrocarbon and (meth) acrylate is usually 99: 1 to 50:50, preferably 95: 5 to 70:30.

  The weight average molecular weight (Mw) of the sulfonic acid group-containing copolymer is a polystyrene conversion value measured by gel permeation chromatography (GPC) using tetrahydrofuran and is in the range of 5,000 to 30,000. Preferably, it is in the range of 8,000 to 25,000, more preferably 10,000 to 20,000. If the weight average molecular weight of the sulfonic acid group-containing copolymer is too large, the droplet size of the organic solvent composition becomes non-uniform, and it is difficult to obtain a toner having a uniform particle size. The heat-resistant storage stability tends to decrease, the environmental dependency and durability of image quality also deteriorate, and it becomes difficult to lower the fixing temperature. If the weight-average molecular weight of the sulfonic acid group-containing copolymer is too small, the fluidity of the resulting toner will be insufficient, the heat-resistant storage stability will decrease, and the environmental dependency and durability of image quality will tend to deteriorate. Show. Below, the raw material of the sulfonic acid group containing copolymer used by this invention and a manufacturing method are explained in full detail.

  The vinyl aromatic hydrocarbon used for the production of the sulfonic acid group-containing copolymer is a compound (monomer) having a structure in which a vinyl group is bonded to the aromatic hydrocarbon. Specific examples include styrene, α -Methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-propylstyrene, 3-propylstyrene, 4-propylstyrene, 2 -Isopropylstyrene, 3-isopropylstyrene, 4-isopropylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 2-methyl-α-methylstyrene, 3-methyl-α-methylstyrene, 4-methyl -Α-methylstyrene, 2-ethyl-α-methylstyrene, 3-ethyl-α-methylstyrene, 4- Cyl-α-methylstyrene, 2-propyl-α-methylstyrene, 3-propyl-α-methylstyrene, 4-propyl-α-methylstyrene, 2-isopropyl-α-methylstyrene, 3-isopropyl-α-methyl Styrene, 4-isopropyl-α-methylstyrene, 2-chloro-α-methylstyrene, 3-chloro-α-methylstyrene, 4-chloro-α-methylstyrene, 2,3-dimethylstyrene, 3,4-dimethyl Styrene, 2,4-dimethylstyrene, 2,6-dimethylstyrene, 2,3-diethylstyrene, 3,4-diethylstyrene, 2,4-diethylstyrene, 2,6-diethylstyrene, 2-methyl-3- Ethylstyrene, 2-methyl-4-ethylstyrene, 2-chloro-4-methylstyrene, 2,3-dimethyl-α-methyls Len, 3,4-dimethyl-α-methylstyrene, 2,4-dimethyl-α-methylstyrene, 2,6-dimethyl-α-methylstyrene, 2,3-diethyl-α-methylstyrene, 3,4- Diethyl-α-methylstyrene, 2,4-diethyl-α-methylstyrene, 2,6-diethyl-α-methylstyrene, 2-ethyl-3-methyl-α-methylstyrene, 2-methyl-4-propyl- α-methylstyrene, 2-chloro-4-ethyl-α-methylstyrene and the like can be mentioned. These vinyl aromatic hydrocarbons can be used alone or in combination of two or more.

  The (meth) acrylate used for the production of the sulfonic acid group-containing copolymer is an acrylic ester or a methacrylic ester. Specific examples include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, acrylic Acrylic acid esters such as n-butyl acid, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, hydroxypropyl acrylate, lauryl acrylate; methyl methacrylate, Ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate Le, hydroxypropyl methacrylate, methacrylic acid esters such as lauryl methacrylate; compounds such as and the like. These (meth) acrylates can be used alone or in combination of two or more.

  Examples of the sulfonic acid group-containing (meth) acrylamide used in the production of the sulfonic acid group-containing copolymer include 2-acrylamide-2-methylpropanesulfonic acid, 2-acrylamide-n-butanesulfonic acid, and 2-acrylamide- n-hexanesulfonic acid, 2-acrylamide-n-octanesulfonic acid, 2-acrylamide-n-dodecanesulfonic acid, 2-acrylamide-n-tetradecanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamide 2-phenylpropanesulfonic acid, 2-acrylamido-2,2,4-trimethylpentanesulfonic acid, 2-acrylamido-2-methylphenylethanesulfonic acid, 2-acrylamido-2- (4-chlorophenyl) propanesulfonic acid, 2-acrylic Mid-2-carboxymethylpropanesulfonic acid, 2-acrylamido-2- (2-pyridine) propanesulfonic acid, 2-acrylamido-1-methylpropanesulfonic acid, 3-acrylamido-3-methylbutanesulfonic acid, 2-methacrylic acid Examples thereof include amido-n-decanesulfonic acid and 4-methacrylamideamidobenzenesulfonic acid. These sulfonic acid group-containing (meth) acrylamides can be used alone or in combination of two or more.

  The sulfonic acid group-containing copolymer can be obtained by copolymerizing each monomer component by any polymerization method such as emulsion polymerization, dispersion polymerization, suspension polymerization, or solution polymerization. Among these polymerization methods, the solution polymerization method is preferable because the copolymerization ratio and the weight average molecular weight can be easily adjusted. As a polymerization initiator used for the production of the sulfonic acid group-containing copolymer, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2 ′ -Azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobisisobutyrate, 4,4'-azobis (4-cyanopentanoic acid), 4,4'-azobis ( 4-cyanovaleric acid), 2,2′-azobis (2-amidinopropane) dibasic acid, 2,2-azobis-2-methyl-N-1,1-bis (hydroxymethyl) -2-hydroxydiethylpropion Azo compounds such as amides and 1,1′-azobis (1-cyclohexanecarbonitrile); 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (N, N -Dimethyleneisobutylamidine), 2,2'-azobis (N, N'-dimethyleneisobutylamidine) dihydrochloride and other diamine compounds; methyl ethyl peroxide, di-t-butyl peroxide, acetyl peroxide, dicumyl Peroxides such as peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, di-isopropylperoxydicarbonate, di-t-butylperoxyisophthalate; Can do.

  The amount of the polymerization initiator used can be arbitrarily selected according to the target weight average molecular weight, but is usually 0.01 to 10 parts by mass, preferably 0 with respect to 100 parts by mass of the total amount of monomers. .1 to 5 parts by mass. In solution polymerization, an anionic polymerization initiator such as alkali metal, butyl lithium, a reaction product of alkali metal and naphthalene, or the like can be used.

  Solvents and dispersants used in solution polymerization and the like can be appropriately selected. Specifically, examples of the hydrocarbon compound include aromatic hydrocarbon compounds such as benzene, toluene, and xylene; saturated hydrocarbon organic compounds such as n-hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, nonane, decane, decalin, and dodecane. A compound; Examples of the oxygen-containing organic compound include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, amyl alcohol, isoamyl alcohol, methyl isobutyl carbinol, 2- Compounds having a hydroxyl group such as ethyl butanol, 2-ethylhexanol, cyclohexanol, furfuryl alcohol, tetrahydrofurfuryl alcohol, ethylene glycol, hexylene glycol, glycerin; propyl ether, isopropyl ether, butyl ether, isobutyl ether N-amyl ether, isoamyl ether, methyl butyl ether, methyl isobutyl ether, methyl n-amyl ether, methyl isoamyl ether, ethyl Aliphatic saturated ethers such as propyl ether, ethyl isopropyl ether, ethyl butyl ether, ethyl isobutyl ether, ethyl n-amyl ether and ethyl isoamyl ether; aliphatic unsaturated ethers such as allyl ether and ethyl allyl ether; anisole, Aromatic ethers such as phenetole, phenyl ether and benzyl ether; cyclic ethers such as tetrahydrofuran, tetrahydropyran and dioxane; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether , Ethylene glycols such as diethylene glycol monobutyl ether; formic acid, Organic acids such as acid, acetic anhydride, butyric acid; butyl formate, amyl formate, propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, amyl acetate, isoamyl acetate, 2-ethylhexyl acetate, cyclohexyl acetate, butylcyclohexyl acetate, propion Organic acid esters such as ethyl acetate, butyl propionate, amyl propionate, butyl butyrate, diethyl carbonate, diethyl oxalate, methyl lactate, ethyl lactate, butyl lactate and triethyl phosphate; methyl isopropyl ketone, methyl isobutyl ketone, ethyl isobutyl Ketones such as ketone, diisobutyl ketone, acetylacetone, diacetone alcohol, cyclohexanone, cyclopentanone, methylcyclohexanone, cycloheptanone; 1,4-dioxane, isophorone, furfural And other oxygen-containing organic compounds.

  The polymerization temperature and polymerization time can be arbitrarily selected depending on the polymerization method and the type of polymerization initiator used, but are usually about 50 to 200 ° C., and the polymerization time is about 0.5 to 20 hours. In the polymerization, a commonly known additive, for example, a polymerization aid such as an amine can be used in combination. The method of recovering the sulfonic acid group-containing copolymer from the system after polymerization is a method of adding a poor solvent to precipitate the copolymer, a method of removing the solvent with steam, a method of removing the solvent under reduced pressure, or heat melting. A method for removing the solvent, a method for freeze-drying, and the like are used.

  The charge control agent used in the present invention is usually 0.1 to 8.0 parts by weight, preferably 0.2 to 5.0 parts by weight, more preferably 100 parts by weight of the binder resin. Is 0.3 to 3.0 parts by mass. If the charge control agent is less than 0.1 parts by mass, the charge may be insufficient and fog may occur. Conversely, if it exceeds 8.0 parts by mass, fog may occur in a low temperature and low humidity environment.

In the production method of the present invention, agglomeration of carbon black in the binder resin is performed by adding and mixing the aluminum coupling agent alone to the organic solvent composition prior to droplet formation in the aqueous dispersion medium. Can be prevented. In addition, since a pretreatment such as a coupling treatment is not required for carbon black, it becomes possible to efficiently produce a negatively chargeable toner.
As the aluminum coupling agent used in the production method of the present invention, those generally used in the field can be used, for example, aluminum alcoholate, aluminum chelate, cyclic aluminum oligomer, etc. can be used. In particular, aluminum alcoholates such as acetoalkoxyaluminum diisopropylate represented by “Plenact AL-M” manufactured by Ajinomoto Fine Techno Co., Ltd. having a structure of the following formula are preferably used.

The aluminum coupling agent used in the present invention is preferably 0.01 to 1.0 part by mass, more preferably 0.05 to 0.8 part by mass with respect to 100 parts by mass of the binder resin. In addition, the aluminum coupling agent used in the present invention is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of carbon black.
If the proportion of the aluminum coupling agent is smaller than the above range, the effect of preventing the aggregation of carbon black cannot be sufficiently obtained.
On the other hand, when the ratio of the aluminum coupling agent is larger than the above range, the droplets are likely to aggregate in the step of forming the droplets of the organic solvent composition, and coarse colored resin particles may increase.

  The organic solvent used in the present invention is preferably an organic solvent capable of dissolving or dispersing the binder resin, carbon black, wax, aluminum coupling agent, and charge control agent described above. Further, the organic solvent is preferably removed when forming the colored resin particles or after forming the colored resin particles. The organic solvent is preferably a volatile solvent having a boiling point of less than 150 ° C. from the viewpoint of easy removal. When the boiling point of the organic solvent is 150 ° C. or higher, the colored resin particles may aggregate when the organic solvent is removed. Examples of volatile organic solvents having a boiling point of less than 150 ° C. include toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, Examples include dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, and methyl isobutyl ketone. Among these, ethyl acetate, toluene, xylene, benzene, methylene chloride, 1,2-dichloroethane, chloroform, carbon tetrachloride and the like are preferable, and ethyl acetate is particularly preferable. These may be used individually by 1 type and may use 2 or more types together. There is no restriction | limiting in particular as usage-amount of an organic solvent, According to the objective, it can select suitably, For example, 40-400 mass parts is preferable with respect to 100 mass parts of binder resin, and 80-300 mass parts is more. Preferably, 100 to 250 parts by mass are more preferable.

  In the present invention, an organic solvent composition containing at least a binder resin, carbon black, wax, an aluminum coupling agent, and a charge control agent is dispersed in an aqueous dispersion medium containing a dispersion stabilizer, whereby an organic solvent is obtained. A droplet of the composition is formed. The method of forming the droplet is not particularly limited, but, for example, (in-line type) emulsifying disperser (trade name: Cavitron, manufactured by Taiheiyo Kiko Co., Ltd.), high-speed emulsifying disperser (manufactured by PRIMIX, trade name: TK Homomixer MARK) Using a device capable of strong stirring, such as type II).

  In the present invention, the aqueous dispersion medium refers to a medium containing water as a main component.

  The aqueous dispersion medium contains a dispersion stabilizer. Examples of the dispersion stabilizer include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metals such as aluminum oxide and titanium oxide. Oxides; metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; inorganic compounds such as; water-soluble polymers such as polyvinyl alcohol, methylcellulose, and gelatin; anionic surfactants; Organic compounds such as nonionic surfactants; amphoteric surfactants; The said dispersion stabilizer can be used 1 type or in combination of 2 or more types.

  Among the above dispersion stabilizers, inorganic compounds, particularly colloids of poorly water-soluble metal hydroxides are preferred. By using a colloid of an inorganic compound, particularly a poorly water-soluble metal hydroxide, the particle size distribution of the colored resin particles can be narrowed, and the residual amount of the dispersion stabilizer after washing can be reduced. The toner thus produced can reproduce the image clearly and has excellent environmental stability.

2. Step of obtaining a suspension of colored resin particles In the production method of the present invention, the above-mentioned 1. The organic solvent is distilled off from the droplets of the organic solvent composition obtained as described above to prepare a suspension of colored resin particles.
A known method can be used to remove the organic solvent from the droplets. For example, there is a method in which the temperature of the organic solvent composition is raised to a temperature equal to or higher than the boiling point of the organic solvent, and the solvent is removed while maintaining the temperature for a predetermined time.

  The colored resin particles may be used as a toner as they are or by adding an external additive. However, the colored resin particles are obtained by using the colored resin particles as a core layer and forming a shell layer different from the core layer on the outside. The so-called core-shell type (or “capsule type”) colored resin particles are preferable. The core-shell type colored resin particles balance the reduction of the fixing temperature and the prevention of aggregation during storage by coating the core layer made of a material having a low softening point with a material having a higher softening point. be able to.

  There is no restriction | limiting in particular as a method of manufacturing a core-shell type colored resin particle using the said droplet mentioned above, It can manufacture by a conventionally well-known method. An in situ polymerization method and a phase separation method are preferable from the viewpoint of production efficiency.

A method for producing core-shell type colored resin particles by in situ polymerization will be described below.
Addition of a polymerizable monomer for forming a shell layer (polymerizable monomer for shell) and a polymerization initiator to an aqueous dispersion medium in which droplets are dispersed, and then polymerizing the core-shell type coloring Resin particles can be obtained.

  The polymerizable monomer means a monomer having a polymerizable functional group. The shell polymerizable monomer is polymerized to form a shell layer. As a main component of the polymerizable monomer for shell, it is preferable to use a monovinyl monomer. Examples of the monovinyl monomer include styrene; styrene derivatives such as vinyl toluene and α-methylstyrene; acrylic acid and methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylic acid 2 Acrylic esters such as ethylhexyl and dimethylaminoethyl acrylate; methacrylic esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate and dimethylaminoethyl methacrylate; acrylonitrile And nitrile compounds such as methacrylonitrile; amide compounds such as acrylamide and methacrylamide; and olefins such as ethylene, propylene, and butylene. These monovinyl monomers can be used alone or in combination of two or more. Among these, it is preferable to use, as a monovinyl monomer, monomers such as styrene, acrylonitrile, and methyl methacrylate that can yield a polymer having a Tg of more than 80 ° C. alone or in combination of two or more.

  As a polymerization initiator used for polymerization of the polymerizable monomer for shell, persulfate metal salts such as potassium persulfate and ammonium persulfate; 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) Water-soluble such as azo initiators such as) propionamide) and 2,2′-azobis- (2-methyl-N- (1,1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide); A polymerization initiator can be mentioned. These can be used alone or in combination of two or more. The amount of the polymerization initiator is preferably 0.1 to 30 parts by mass, and more preferably 1 to 25 parts by mass with respect to 100 parts by mass of the polymerizable monomer for shell.

  The polymerization temperature of the shell layer is preferably 50 ° C. or higher, more preferably 60 to 95 ° C. The polymerization reaction time is preferably 1 to 20 hours, more preferably 2 to 15 hours.

3. Obtained colored resin particles Suspension of colored resin particles obtained as described above was subjected to filtration, washing to remove the dispersion stabilizer, dehydration, and drying operations several times as necessary. Preferably it is repeated.

  As the above washing method, when an inorganic compound is used as the dispersion stabilizer, the dispersion stabilizer can be dissolved in water and removed by adding an acid or alkali to the suspension of colored resin particles. preferable. When a colloid of a poorly water-soluble inorganic hydroxide is used as the dispersion stabilizer, it is preferable to adjust the pH of the colored resin particle aqueous dispersion to 6.5 or less by adding an acid. As the acid to be added, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as formic acid and acetic acid can be used. Particularly, since the removal efficiency is large and the burden on the manufacturing equipment is small, Sulfuric acid is preferred.

  Various known methods and the like can be used as the method of dehydration and filtration, and there is no particular limitation. Examples thereof include a centrifugal filtration method, a vacuum filtration method, and a pressure filtration method. Also, the drying method is not particularly limited, and various methods can be used.

As described above, colored resin particles are obtained.
Hereinafter, the colored resin particles constituting the toner will be described. The colored resin particles described below include both core-shell type and non-core type.

  The volume average particle diameter (Dv) of the colored resin particles is preferably 4 to 12 μm, more preferably 5 to 10 μm. When Dv is less than 4 μm, the fluidity of the toner is lowered, the transferability may be deteriorated, and the image density may be lowered. When Dv exceeds 12 μm, the resolution of the image may decrease.

The colored resin particles have a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of preferably 1.0 to 1.3, more preferably 1. 0-1.2. If Dv / Dn exceeds 1.3, transferability, image density, and resolution may decrease. The volume average particle diameter and the number average particle diameter of the colored resin particles can be measured using, for example, a particle size analyzer (trade name: Multisizer, manufactured by Beckman Coulter).
Thus, in the present invention, a negatively chargeable toner having a narrow particle size distribution can be obtained even when produced by a polymerization method.

From the viewpoint of image reproducibility, the average circularity of the colored resin particles of the present invention is preferably 0.96 to 1.00, more preferably 0.97 to 1.00, and 0.98 to More preferably, it is 1.00.
When the average circularity of the colored resin particles is less than 0.96, the fine line reproducibility of printing may be deteriorated.

  In the present invention, the circularity is defined as a value obtained by dividing the circumference of a circle having the same projected area as the particle image by the circumference of the projected image of the particle. The average circularity in the present invention is used as a simple method for quantitatively expressing the shape of the particles, and is an index indicating the degree of unevenness of the colored resin particles. The average circularity is determined by the colored resin particles. 1 is shown in the case of a perfect sphere, and the value becomes smaller as the surface shape of the colored resin particles becomes more complicated.

4). Step of Producing Toner from Colored Resin Particles In the production method of the present invention, the above colored resin particles can be used as a toner as they are. An external additive is preferably adhered to the surface of the toner to form a one-component toner (developer). The one-component toner may be further mixed and stirred together with carrier particles to form a two-component developer.

  The stirrer that performs the external addition treatment is not particularly limited as long as the stirrer can attach the external additive to the surface of the colored resin particles. For example, an FM mixer (trade name, manufactured by Nippon Coke Kogyo Co., Ltd.), Super Mixer (: trade name, manufactured by Kawada Seisakusho), Q mixer (: trade name, manufactured by Nihon Coke Kogyo Co., Ltd.), mechano-fusion system (: trade name, manufactured by Hosokawa Micron), and mechano mill (: trade name, manufactured by Okada Seiko Co., Ltd.) The external addition treatment can be performed using a stirrer capable of mixing and stirring.

Examples of the external additive include inorganic fine particles composed of silica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, calcium carbonate, calcium phosphate, and / or cerium oxide; polymethyl methacrylate resin, silicone resin, and / or melamine Organic fine particles made of a resin or the like; Among these, inorganic fine particles are preferable, and among inorganic fine particles, silica and / or titanium oxide are preferable, and fine particles made of silica are particularly preferable.
These external additives can be used alone or in combination of two or more. Among these, it is preferable to use two or more types of silica having different particle diameters in combination.

  In the present invention, the external additive is usually used in a proportion of 0.05 to 6 parts by mass, preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the colored resin particles. When the added amount of the external additive is less than 0.05 parts by mass, a transfer residue may occur. If the amount of the external additive exceeds 6 parts by mass, fog may occur.

5. Toner obtained by the production method of the present invention The toner obtained through the above steps has a good dispersion of carbon black as a colorant, high chargeability, excellent transfer efficiency and low-temperature fixability, and occurrence of white spots. And a negatively chargeable toner capable of obtaining an image having a sufficient image density.
The charge control is performed by preparing an organic solvent composition by mixing a binder resin, carbon black, wax, an aluminum coupling agent, and a charge control agent of a copolymer having a sulfonic acid copolymer unit in a specific range. It was possible to obtain the negatively chargeable toner of the present invention in which aggregation of carbon black was suppressed by mixing with an aluminum coupling agent while keeping the toner charge amount high with the agent.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited only to these examples. Parts and% are based on mass unless otherwise specified.
The test methods performed in the examples and comparative examples are as follows.

1. Production of sulfonic acid group-containing copolymer (charge control agent) [Production Example 1]
In a 3 L reaction vessel, 900 parts of toluene, 83 parts of styrene, 14.5 parts of 2-ethylhexyl acrylate, 2.5 parts of 2-acrylamido-2-methylpropanesulfonic acid, and 2,2′-azobis (2,4- Dimethylvaleronitrile) 2.4 parts was charged, and a copolymerization reaction was carried out at 80 ° C. for 8 hours while stirring. After completion of the reaction, the solvent was removed by freeze-drying to obtain the charge control agent of Production Example 1 (copolymerization ratio of sulfonic acid group-containing (meth) acrylamide monomer unit: 2.5% by mass).

[Production Example 2]
In Production Example 1, a production example was prepared in the same manner as in Production Example 1 except that the amount of the monomer used for copolymerization was changed to 16 parts of 2-ethylhexyl acrylate and 1 part of 2-acrylamido-2-methylpropanesulfonic acid. 2 was obtained (copolymerization ratio of sulfonic acid group-containing (meth) acrylamide monomer unit: 1.0% by mass).

[Production Example 3]
In Production Example 1, the same procedure as in Production Example 1 was carried out except that the amount of monomer used for copolymerization was changed to 13 parts of 2-ethylhexyl acrylate and 4 parts of 2-acrylamido-2-methylpropanesulfonic acid. 3 (a copolymerization ratio of a sulfonic acid group-containing (meth) acrylamide monomer unit: 4.0% by mass, a weight average molecular weight: 18,000, a glass transition temperature: 57.6 ° C.).

[Production Example 4]
In Production Example 1, the same procedure as in Production Example 1 was carried out except that the amount of monomer used for copolymerization was changed to 10 parts 2-ethylhexyl acrylate and 7 parts 2-acrylamido-2-methylpropanesulfonic acid. 4 (a copolymerization ratio of a sulfonic acid group-containing (meth) acrylamide monomer unit: 7.0% by mass) was obtained.

[Production Example 5]
In Production Example 1, the amount of monomer used for copolymerization was changed to 16.5 parts of 2-ethylhexyl acrylate and 0.5 parts of 2-acrylamido-2-methylpropanesulfonic acid, and was the same as Production Example 1. Thus, the charge control agent of Production Example 5 (copolymerization ratio of sulfonic acid group-containing (meth) acrylamide monomer unit: 0.5% by mass) was obtained.

2. Production of negatively chargeable toner [Example 1]
77 parts of styrene and 23 parts of n-butyl acrylate as a polymerizable monomer, 0.7 parts of divinylbenzene as a crosslinkable polymerizable monomer, 1.5 parts of t-dodecyl mercaptan as a molecular weight regulator, polymerization initiator 4.0 parts (manufactured by NOF Corporation, trade name: perbutyl O) and 100 parts of toluene were put into a reactor equipped with a stirring blade, and the temperature was raised to 90 ° C. to initiate the polymerization reaction. After reacting for 6 hours, the mixture was further heated to 100 ° C. and the solvent was distilled off for 6 hours to obtain a binder resin.

  On the other hand, an aqueous solution in which 9.7 parts of sodium hydroxide was dissolved in 50 parts of ion-exchanged water and an aqueous solution in which 9.7 parts of sodium hydroxide were dissolved in 250 parts of ion-exchanged water were gradually added at room temperature with stirring. Then, an aqueous dispersion medium of magnesium hydroxide colloid (slightly water-soluble metal hydroxide colloid) was prepared.

100 parts of the above binder resin, 0.25 parts of aluminum coupling agent (manufactured by Ajinomoto Fine-Techno Co., Ltd., trade name: Preneact AL-M), carbon black (manufactured by Mitsubishi Chemical Corporation, product name: # 25B, number average primary particles) diameter 40 nm, DBP oil absorption of 64cm ³ / 100g) 9 parts of the charge control agent 2.0 parts in production example 1, glycerol ester mixture as a wax as a charge control agent (manufactured by NOF Corporation, trade name: WEP-7) 2 Parts, 5 parts of microcrystalline wax (manufactured by Nippon Seiki Co., Ltd., trade name: Hi-Mic-2045) and 200 parts of ethyl acetate are heated to 40 ° C. and stirred, and then a disperser (manufactured by Shinmaru Enterprises, product) The organic solvent composition was obtained by making it disperse | distribute using a name: Dynomill. The organic solvent composition is charged into the aqueous dispersion medium and stirred, and then subjected to high shear for 1 minute at a rotational speed of 15,000 rpm using an in-line type emulsifying disperser (trade name: Cavitron, manufactured by Taiheiyo Kiko Co., Ltd.). Stirring to form fine droplets of the organic solvent composition in the aqueous dispersion medium. Thus, an aqueous dispersion medium in which droplets of the organic solvent composition were dispersed was prepared. Then, after putting in a reactor equipped with a stirring blade, the temperature was raised to 75 ° C., and the solvent was removed for 4 hours to obtain a suspension of colored resin particles. Further, the temperature was raised to 90 ° C., and 2,2′-azobis (2-methyl-N—) which is a polymerization initiator for shell dissolved in 2 parts of methyl methacrylate as a polymerizable monomer for shell and 10 parts of ion-exchanged water. (2-Hydroxyethyl) -propionamide) 0.5 part was added, reacted for 3 hours, cooled with water to stop the reaction, colored resin particles were used as a core layer, and a shell layer different from the core layer was formed on the outside. did.
Next, sulfuric acid was added dropwise at room temperature while stirring the suspension, and acid washing was performed until the pH became 6.5 or lower. Filtration separation was performed, 500 parts of ion-exchanged water was added to the obtained solid content to make a slurry again, and water washing treatment (washing, filtration and dehydration) was repeated several times. Finally, filtration separation was performed, and the obtained solid content was put in a container of a dryer and dried at 40 ° C. for 24 hours.

  To 100 parts of the dried colored resin particles, 1.0 part of negatively charged silica (manufactured by Clariant) having a hydrophobized average primary particle diameter of 40 nm, and negatively charged having an average hydrophobized average primary particle diameter of 12 nm as external additives 0.6 parts of functional silica (manufactured by Nippon Aerosil Co., Ltd.) and a stirring blade using a 10 L lab-scale high-speed stirring device (manufactured by Nippon Coke Industries, Ltd., trade name: FM mixer) having a cooling jacket The toner was mixed and stirred at a peripheral speed of 40 m / sec and an external addition treatment time of 300 seconds to carry out the external addition treatment, whereby the negatively chargeable toner of Example 1 was obtained.

[Example 2]
In Example 1, a negatively chargeable toner of Example 2 was obtained in the same manner as in Example 1 except that the amount of the wax mixed was 7 parts of microcrystalline wax.

[Example 3]
In Example 1, a negatively chargeable toner of Example 3 was obtained in the same manner as in Example 1 except that the amount of the wax mixed was 7 parts of the glycerin ester mixture.

[Example 4]
In Example 1, a negatively chargeable toner of Example 4 was obtained in the same manner as in Example 1 except that the amount of wax mixed was 7 parts of paraffin wax (trade name: LUVAX1211 manufactured by Nippon Seiki Co., Ltd.). .

[Example 5]
In Example 1, a negatively chargeable toner of Example 5 was obtained in the same manner as Example 1 except that the charge control agent of Production Example 1 was replaced with the charge control agent of Production Example 2.

[Example 6]
In Example 1, a negatively chargeable toner of Example 6 was obtained in the same manner as in Example 1 except that the charge control agent of Production Example 1 was replaced with the charge control agent of Production Example 3.

[Comparative Example 1]
In Example 1, a negatively chargeable toner of Comparative Example 1 was obtained in the same manner as in Example 1 except that the aluminum coupling agent was not mixed.

[Comparative Example 2]
In Comparative Example 1, a negatively chargeable toner of Comparative Example 2 was obtained in the same manner as Comparative Example 1 except that the amount of carbon black mixed was 10 parts.

[Comparative Example 3]
In Comparative Example 1, a negatively chargeable toner of Comparative Example 3 was obtained in the same manner as Comparative Example 1 except that the amount of carbon black mixed was 6 parts.

[Comparative Example 4]
In Example 1, a negatively chargeable toner of Comparative Example 4 was obtained in the same manner as in Example 1 except that the charge control agent of Production Example 1 was replaced with the charge control agent of Production Example 4.

[Comparative Example 5]
In Example 1, a negatively chargeable toner of Comparative Example 5 was obtained in the same manner as in Example 1 except that the charge control agent of Production Example 1 was replaced with the charge control agent of Production Example 5.

3. Evaluation of toner characteristics The characteristics of the negatively chargeable toners of the above examples and comparative examples were examined. Details are as follows.

(1) Image Density For image density measurement, a commercially available non-magnetic one-component developing type printer was used, and the toner cartridge was filled in the toner cartridge of the developing device, and then the printing paper was set.
After being left for 24 hours in a normal temperature and normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%), printing was performed at a print density of 5% in the same environment.
Black solid printing (printing density 100%) was performed, and the printing density of the black solid image was measured using a reflective image densitometer (trade name: RD918, manufactured by Macbeth).
<passing grade>
In this test, when the image density is 1.48 or more, the evaluation of the image density required for the toner is evaluated as acceptable.

(2) Resistance value (volume resistivity value) (log Ω / cm)
About 3 g of colored resin particles were placed in a tablet molding machine having a diameter of 5 cm, and a test piece was prepared by applying a load of about 100 kg for 1 minute. By using the test piece and measuring with a dielectric loss measuring instrument (manufactured by Ando Electric Co., Ltd., model name “TRS-10 type”) under the conditions of a temperature of 30 ° C. and a frequency of 1 kHz, The volume resistivity value was determined.
<passing grade>
In this test, when the volume resistivity value is 10.70 (log Ω / cm) or more, the evaluation of the image density required for the toner is acceptable.

(3) Charge amount (μC / g)
9.5 g of the carrier and 0.5 g of the toner sample are weighed, put into a glass bottle with a capacity of 30 cc, and rotated for 30 minutes at 150 rpm, and then blow-off meter (trade name: TB manufactured by Kyocera Chemical Co., Ltd.). -203), nitrogen gas was blown at a pressure of 4.5 kPa and sucked at a pressure of 9.5 kPa, and the blow-off charge amount was measured.
The measurement was performed at a temperature of 23 ° C. and a relative humidity of 50%.
<passing grade>
In this test, when the blow-off charge amount is −18.0 μC / g or less (absolute value is 18 or more), the evaluation of the charge amount required for the toner is evaluated as acceptable.

(4) Transfer efficiency Using a commercially available non-magnetic one-component development type printer, after standing overnight in an environment of normal temperature and humidity (N / N) (temperature: 23 ° C., humidity: 50%), from the beginning Continuous printing was performed with a 5% density printed image, and the toner consumption amount and the waste toner recovery amount were obtained every 500 sheets, and the transfer efficiency was calculated by the following formula.
Transfer efficiency (%) = (toner consumption (g) −waste toner recovery amount (g)) / toner consumption (g) × 100
<passing grade>
In this test, when the transfer efficiency was 80% or more, the evaluation of the transfer efficiency required for the toner was set to pass (A). On the other hand, when the transfer efficiency was less than 80%, the transfer efficiency was evaluated as rejected (F).

(5) Minimum fixing temperature Toner in the developing device of the printer using a printer modified so that the temperature of the fixing roll of a commercially available non-magnetic one-component developing type printer (printing speed = 32 sheets / min) can be changed. After the cartridge was filled with 100 g of toner, printing paper was set and a fixing test was performed as follows.
In the fixing test, black solid (printing density 100%) is printed, the temperature of the fixing roll of the modified printer is changed from 200 ° C. to 5 ° C., and the toner fixing rate at each temperature is measured. -The relationship of the fixing rate was obtained. Note that, at each temperature changed by 5 ° C., the temperature state was maintained for 5 minutes or more in order to stabilize the temperature of the fixing roll.
The fixing rate was calculated from the ratio of image density before and after the tape was peeled off in the black solid (printing density 100%) printing area. That is, assuming that the image density (ImageDensity) before tape peeling is ID (front) and the image density after tape peeling is ID (back), the fixing ratio can be calculated by the following calculation formula 2.
Calculation formula 2 = Fixing rate (%) = (ID (rear) / ID (front)) × 100
Here, the tape peeling operation means that an adhesive tape (manufactured by Sumitomo 3M Co., Ltd., trade name: Scotch Mending Tape 810-3-18) is pasted on the measurement part of the test paper, and a disk-shaped metal roll (diameter 15 cm × thickness). 2 cm, weight = 1 kg), and a pressure is applied at a constant pressure to adhere, and then the adhesive tape is peeled in a direction along the paper at a constant speed. The image density was measured using a reflection type image densitometer (manufactured by Macbeth, trade name: RD914). In this fixing test, the minimum fixing roll temperature at which the fixing rate is 80% or more was defined as the minimum fixing temperature of the toner.

(6) Evaluation of white spots After using a commercially available non-magnetic one-component development type printer in a room temperature and normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%), it was left overnight. Continuous printing is performed with a 5% density printed image from the beginning, and a solid black printed image is printed every 500 sheets to check for the occurrence of white spots.
<passing grade>
In this test, the case where no white spot was visually observed was regarded as pass (A), and the case where white spot was found was regarded as reject (F).

4). Evaluation Results Table 1 shows the compositions and evaluation results of the amounts charged in the production of the negatively chargeable toners of Examples 1 to 6 and Comparative Examples 1 to 5. In Table 1 and the following description, “copolymerization ratio” means the copolymerization ratio (mass%) of 2-acrylamido-2-methylpropanesulfonic acid units in the sulfonic acid group-containing copolymer. .

5. Summary of Toner Evaluation Hereinafter, the toner evaluation will be examined with reference to Table 1.
First, the toners of Comparative Examples 1 to 3 are examined. These are toners manufactured without using an aluminum coupling agent.
The toners of Comparative Examples 1 to 3 have different carbon black contents. When the carbon black content is as small as 6 parts as in Comparative Example 3, there are no problems with the resistance value, the charge amount, the transfer efficiency, the minimum fixing temperature, and the white spot, but the image density is low, so it is rejected. It is. On the other hand, as in Comparative Example 1 and Comparative Example 2, increasing the carbon black content to 9 parts or 10 parts improves the image density while lowering the resistance value and the charge amount. Will occur and print defects will occur.
In view of the above, a negatively chargeable toner that has high chargeability, excellent transfer efficiency and low-temperature fixability only by adjusting the carbon black content, does not cause white spots, and provides an image having a sufficient image density. It cannot be manufactured.

Next, the toners of Comparative Example 4 and Comparative Example 5 will be examined. From Table 1, these toners are toners using an aluminum coupling agent and a charge control resin having a copolymerization ratio of 7% by mass (Comparative Example 4) or 0.5% by mass (Comparative Example 5).
The toner of Comparative Example 4 has an excessively high copolymerization ratio of 7% by mass, so that the dispersibility of carbon black is not sufficient. As a result, the toner image density is as low as 1.41 and the resistance value is 10.62 ( logΩ / cm). On the other hand, the toner of Comparative Example 5 has a low copolymerization ratio of 0.5% by mass, so the effect of imparting negative chargeability is small. As a result, the toner image density is as low as 1.42, and the absolute value of the charge amount is low. 17.2 μC / g is high and transfer efficiency is low.

On the other hand, the toners of Examples 1 to 6 are toners using an aluminum coupling agent and a charge control resin having a copolymerization ratio of 1.0 to 4.0% by mass. From Table 1, these toners satisfy the acceptance criteria of all the toner evaluation items.
From the above results, by using an aluminum coupling agent and further using a sulfonic acid group-containing copolymer in which the copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide monomer unit is within the specific range of the present invention. It can be seen that it is possible to produce a negatively chargeable toner having high chargeability, excellent transfer efficiency and low temperature fixability, no white spots, and an image having a sufficient image density.

Claims (6)

An organic solvent composition is obtained by dispersing at least a binder resin, carbon black, wax, and a charge control agent in an organic solvent, and the organic solvent composition is suspended in an aqueous dispersion medium containing a dispersion stabilizer. A method of producing a negatively chargeable toner comprising: forming a droplet of an organic solvent composition by turbidity; and removing the organic solvent from the droplet to obtain a suspension of colored resin particles. And
The organic solvent composition further includes an aluminum coupling agent, and
The organic solvent composition is obtained by copolymerizing vinyl aromatic hydrocarbon, (meth) acrylate, and sulfonic acid group-containing (meth) acrylamide as the charge control agent, and is a sulfonic acid group-containing (meth) acrylamide single unit. A method for producing a negatively chargeable toner, comprising a sulfonic acid group-containing copolymer having a copolymerization ratio of a monomer unit of 0.8 to 6.0% by mass.   The method for producing a negatively chargeable toner according to claim 1, wherein the wax includes an ester wax.   The method for producing a negatively chargeable toner according to claim 1, wherein the wax includes a hydrocarbon wax.   The copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide monomer unit of the sulfonic acid group-containing copolymer is 1.0 to 4.5% by mass. The method for producing a negatively chargeable toner according to one item.   The method for producing a negatively chargeable toner according to any one of claims 1 to 4, wherein the sulfonic acid group-containing copolymer has a weight average molecular weight of 5,000 to 30,000.   The organic solvent composition contains 0.1 to 8.0 parts by mass of the charge control agent with respect to 100 parts by mass of the binder resin. A method for producing the negatively chargeable toner according to claim.