JP6540432B2 - Method of manufacturing negatively chargeable toner - Google Patents

Description

  The present invention relates to a method for producing a negatively chargeable toner that can be used for developing an image forming apparatus using electrophotography, such as copiers, facsimiles, and printers.

  In recent years, the need for colorization has increased for image forming apparatuses such as multifunction machines, facsimiles, and printers using electrophotography. In color printing, since it is required to reproduce high resolution and clear tone like photographs, color toners that can cope with it are required. For such toner, from the viewpoint of environmental stability from the viewpoint of preventing image quality deterioration due to changes in the environment such as temperature and humidity, print durability from the viewpoint of printing cost reduction, and power consumption reduction. Various printing performances such as low temperature fixability are required.

In order to meet the above requirements, a toner having a small particle diameter and a spherical shape that can achieve both good transferability and dot reproducibility is suitable, and a wet method has been proposed as a method for producing the toner. The conventional grinding method has a low yield and consumes a lot of energy for grinding, especially when producing toner with a small particle diameter, whereas the wet method has a high yield and does not require the grinding step. Energy consumption is also low, and spherical toner can be easily manufactured.
When colored resin particles are obtained by a wet method, spherical resin particles having a smaller particle diameter can be formed at the stage of forming the particles, and the particle size distribution can be made sharper than in the conventional pulverizing method. It has a great advantage.

  However, with the further increase in the requirements for high resolution and high image quality in recent years, problems that must be solved even with wet process toners are pointed out.

  When the toner is manufactured by the above-mentioned wet method, it is difficult to uniformly disperse the pigment serving as the colorant in the toner, and there is a problem that the formed image density is lowered. Further, as a solution to this problem, if the amount of pigment added to the toner is increased to obtain a sufficient image density, the pigment coagulates in the toner and the charging performance of the toner becomes unstable. Problems such as hollowing out and toner scattering occur.

  As a method of solving the above problems, Patent Document 1 discloses that when a toner is manufactured by a wet method, using a pigment which has been subjected to a coupling treatment in advance with a coupling agent, the dispersibility of the colorant is improved and the toner is charged. It is disclosed that the stability is stabilized, an image having a sufficient image density is obtained, and the occurrence of hollow defects and the scattering of toner are prevented.

JP, 2005-165155, A

However, when Patent Document 1 was examined, in paragraph [0006], a suspension polymerization method, an emulsion dispersion method (referred to as a “solution suspension method” in the present specification), an emulsion polymerization aggregation method, etc. Although described, in the examples, toner production is performed 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 carbon black in the toner becomes insufficient, and the hollowing out occurs. Etc. will occur.
In the dissolution and suspension method, first, a binder resin, a colorant and, if necessary, other additives are mixed with an organic solvent to obtain an organic solvent composition, which contains a dispersion stabilizer Disperse in aqueous dispersion medium. Next, droplets of the organic solvent composition are formed by applying a high shear to the aqueous dispersion medium in which the organic solvent composition is dispersed using an in-line type emulsification disperser or the like. Thereafter, the organic solvent is distilled off from the droplets to obtain a suspension of colored resin particles, which are subjected to filtration with a filter, washing, and drying to obtain colored resin particles.
While the dispersion system of the colorant is the oil phase in the dissolution suspension method, the difference that it is the water phase in the emulsion polymerization aggregation method described as an example in Patent Document 1 greatly affects the dispersibility of carbon black. Is considered to contribute to this problem.
Also, generally, when carbon black is used as a colorant, the electrical resistance of the toner is reduced, so it is necessary to use a highly chargeable charge control agent. However, a negatively chargeable toner using a highly chargeable charge control agent It is considered that the cause is that the carbon black is easily aggregated when obtaining.

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

  As a result of intensive studies to solve the above problems, the present inventor uses an organic solvent composition further 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 problem 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, a wax, and a charge control agent in an organic solvent, and the organic solvent composition is dispersed into a dispersion stabilizer. A step of forming droplets of the organic solvent composition by suspending it in an aqueous dispersion medium containing it, 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 comprises an aluminum coupling agent, and the organic solvent composition comprises, as the charge control agent, a vinyl aromatic hydrocarbon and (meth) acrylate. And a sulfonic acid group-containing (meth) acrylamide, and the copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide monomer unit is 0.8 to 6.0 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 the present invention, the copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide monomer unit of the sulfonic acid group-containing copolymer is preferably 1.0 to 4.5% by mass.

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

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

  According to the manufacturing method of the present invention as described above, carbon black as a coloring agent is well dispersed by using an organic solvent composition containing an aluminum coupling agent and a specific sulfonic acid group-containing copolymer. The present invention provides a method for efficiently producing a negatively chargeable toner which has high chargeability, is excellent in transfer efficiency and low temperature fixability, does not generate white spots and has 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, a wax, and a charge control agent in an organic solvent, and the organic solvent composition is dispersed. A step of forming droplets of an organic solvent composition by suspending in an aqueous dispersion medium containing a stabilizer, and a step of distilling off the organic solvent from the droplets to obtain a suspension of colored resin particles A method of producing a negatively chargeable toner, the organic solvent composition further comprising an aluminum coupling agent, and the organic solvent composition further comprising a vinyl aromatic hydrocarbon as the charge control agent. A copolymer of (meth) acrylate and a 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" generically refers to 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 (hereinafter, may be simply referred to as "toner") of the present invention will be described.
The method for producing a toner according to the present invention comprises suspending an organic solvent composition containing at least a binder resin, carbon black, wax, an aluminum coupling agent, and a charge control agent in an aqueous dispersion medium containing a dispersion stabilizer. The step of forming a droplet of the organic solvent composition by turbidizing, and the step of distilling off the organic solvent from the droplet to obtain a suspension of colored resin particles are included.
Hereinafter, the process of forming droplets of the organic solvent composition, the process of obtaining a suspension of the colored resin particles, the process of manufacturing the toner using the colored resin particles, and the toner obtained by the manufacturing 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 process shown below.

(1) Preparation of Organic Solvent Composition An organic solvent composition is obtained by dispersing a binder resin, carbon black, a wax, an aluminum coupling agent, and a charge control agent in an organic solvent.
A dispersing machine is suitably used to obtain an organic solvent composition by dissolving or dispersing the binder resin or the like in the organic solvent. As a dispersing machine used for stirring the organic solvent composition, a media type dispersing machine, in-line type emulsification and dispersing machine (manufactured by Pacific Kiko Co., Ltd., trade name: Milder), high speed emulsification / dispersion machine (manufactured by Tokushu Kika Kogyo, trade name): There may be mentioned devices capable of strong shearing such as T. K. Homomixer MARK type II), among which a media type dispersing machine is preferred.
In the media type disperser, the rotor is rotatably disposed in the stator, the space formed by the stator and the rotor is filled with media particles, and the media particles are moved by the rotating rotor. Media type dispersers include a horizontal cylinder type, a vertical cylinder type, an inverted triangle type, and the like, depending on the shape and placement of the stator. Specific examples of the media type dispersing machine 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), Dyno mill (product name) And Shinkoru Enterprises, Inc., Picomill (product name, manufactured by Asada Iron Works, Ltd.), Star Mill (product name, manufactured by Ashizawa Finetech), 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 method such as emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization and the like. There are no particular limitations on the state of the resin when it is dissolved in a solvent, as long as it dissolves well in the solvent, and various states such as those dried after polymerization, those in a slurry state, those in a solution state apply. it can. Those polymerized in an aqueous medium are preferably added to the solvent after being dewatered to some extent, 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 the like, but styrene is particularly preferable because dispersion stabilization in a solvent can be easily performed. Resins are preferred. The styrene resin may be a homopolymer of styrene or a copolymer of another vinyl monomer and styrene. As monomers for forming a copolymer with styrene, olefins, vinyl halides, vinyl esters, unsaturated carboxylic acids (esters of unsaturated carboxylic acids), glycidyl compounds, vinyl ethers, vinyl ketones, N-vinyl compounds, dienes, These include nitriles and compounds containing two or more vinyl groups.

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, and the printing density is reduced. In order to increase the printing density, it is conceivable to increase the amount of carbon black added, but when the amount added is increased, there arises a problem that the charge amount of the toner obtained is reduced. In order to increase the amount of charge, it is conceivable to use a charge control agent of high chargeability, but when using a charge control agent of high chargeability to obtain a negatively chargeable toner, there arises a problem that carbon black aggregates. . Because of these problems, it has been difficult to produce toners that meet well-balanced high standards for many requirements in the prior art production methods.
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 content of carbon black is less than 1 part by mass with respect to 100 parts by mass of the binder resin, there is a possibility that the print density of the toner after production may decrease, and if it exceeds 15 parts by mass, the toner after production There is a risk that the electrical resistance may decrease.
The content of carbon black in the organic solvent composition is more preferably 5 to 13 parts by mass, and still more 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 diameter of carbon black is less than 10 nm, the dispersibility of the toner after production may be reduced, and if it exceeds 100 nm, the color developability of the toner after production may be reduced.
The number average primary particle diameter of carbon black used in the production method of the present invention is more preferably 15 to 90 nm, and still more preferably 20 to 70 nm.
The number average primary particle diameter of carbon black can be measured, for example, using a particle size analyzer (trade name "SALD" manufactured by Shimadzu Corporation).

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 K 6221.

A commercially available carbon black can also be used.
Examples of carbon blacks suitable for the above-mentioned number average primary particle diameter and DBP oil absorption amount include carbon black (product name: # 25B manufactured by Mitsubishi Chemical Co., Ltd., number average primary particle diameter 40 nm, DBP oil absorption amount 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. , Brand name Printex G; pH 9, number average primary particle diameter 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.
One of these carbon blacks may be used alone, or two or more thereof may be used in combination.

  The wax used in the present invention refers to an additive that improves 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 preferably used in the present invention is more preferably a polyfunctional ester wax, for example, pentaerythritol ester compounds such as pentaerythritol tetrapalmitate, pentaerythritol tetrabehenate and 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, dipentaerythritol hexapalmitate, etc .;

  The acid value of the ester wax is preferably 1.0 mg KOH / g or less, more preferably 0.6 mg KOH / g or less, and still more preferably 0.3 mg KOH / g or less. If the acid value is more than 1.0 mg KOH / g, the storage stability may be deteriorated. The acid value of the ester wax is a value measured in accordance with JIS K 0070, which is a standard fat and oil analysis method established by the Japan Industrial Standards Committee (JISC).

The hydroxyl value of the ester wax is preferably 10 mg KOH / g or less, more preferably 6 mg KOH / g or less, and still more preferably 3 mg KOH / g or less. If the hydroxyl value is more than 10 mg KOH / g, the storage stability may be deteriorated. The hydroxyl value of the ester wax is a value measured in accordance with JIS K 0070, which is a standard fat and oil analysis method established by the Japan Industrial Standards Committee (JISC).
It is more preferable that the said ester wax satisfy | fills the conditions of the acid value and hydroxyl value which were mentioned above.

The ester wax is preferably used in an amount of 2 to 10 parts by mass, and 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 which forms a molecular chain only by a C—H bond and a C—C bond. Examples of the hydrocarbon include microcrystalline wax, paraffin wax, polyethylene wax, polypropylene wax, Fischer-Tropsch wax and the like. Among these, microcrystalline wax having a low melting point is preferable in view of the low volatile matter at the time of fixing and the improvement of low temperature fixing property.
The hydrocarbon-based wax preferably has a melt viscosity of 6 to 15 [mPa · S] at 140 ° C.
Furthermore, the weight loss of the hydrocarbon wax at 165 ° C. is preferably 10% by mass or less. Thereby, the volatile matter 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 hydrocarbon wax preferably has a low melting point from the viewpoint of improving low-temperature fixability, preferably one having a melting point of 50 ° C. to 90 ° C., and one having a melting point of 55 ° C. to 82 ° C. The temperature is more preferably 60 to 78 ° C. When the melting point is less than 50 ° C., the hydrocarbon wax may adversely affect the heat resistant storage stability, and when it exceeds 90 ° C., cold offset may easily occur during fixation at a low temperature. Furthermore, when dispersing hydrocarbon-based wax in a liquid, once the hydrocarbon-based wax is melted in the liquid and cooled, a dispersion is prepared, but if the melting point of the hydrocarbon-based wax exceeds 90 ° C. The boiling point of the liquid in which the hydrocarbon wax is dispersed needs to be higher than 90.degree. When such a solvent is used, the temperature may be higher when removing the solvent compared to the glass transition point of the toner, and the toner may cause blocking. As a means for lowering the melting point of hydrocarbon waxes, it is common to lower the molecular weight of hydrocarbon waxes. However, when the molecular weight of the hydrocarbon wax is simply lowered, the volatile content increases. The microcrystalline wax is also preferable from the viewpoint of lowering the melting point of the hydrocarbon wax and reducing volatile matter at the time of fixing of the hydrocarbon wax.

  In addition, hydrocarbon-based wax satisfying such requirements may deteriorate the separability between the roller and the paper at the time of fixing on the paper. Therefore, it is necessary to make the toner have a gel content to some extent. The gel content in the toner makes it possible to improve the separation between the roller and the paper at the time of fixing. The gel content in the toner can be measured as a tetrahydrofuran (THF) insoluble content. As a THF insoluble matter, 5 mass%-25 mass% are preferable. When the THF insoluble matter is 5% by mass or more, the deterioration of the separability at the time of fixing is suppressed. If the content is 25% by mass or less, the deterioration of the low temperature fixability is suppressed.

  The melt viscosity of the hydrocarbon wax is measured by Brookfield method using a B-type viscometer. The measurement is carried out by heating the measurement sample from normal temperature, and a value at a temperature above the melting temperature of the sample and a temperature at 140 ° C. which approximates the actual fixing temperature is preferable.

Besides the above waxes, for example, natural waxes such as jojoba; mineral waxes such as ozokerite; and the like can be used.
As the wax, one or more of the above-described waxes 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 toner particles exhibiting a dispersed state of wax can be defined by the measurement shown below. The total amount of wax in the toner particles is obtained by the DSC (differential scanning calorimeter) method. The toner sample and the wax single-piece sample are respectively measured by the following measuring apparatus and conditions, and are obtained from the ratio of the amount of heat absorption of the wax obtained.

Measurement device: DSC device (DSC 60: manufactured by Shimadzu Corporation)
・ Sample amount: about 5 mg
· Temperature rise 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).
Wax total amount (% by mass) = (heat absorption amount of wax of toner sample (J / g)) × 100) / (heat absorption amount of wax alone (J / g)) Formula (1)

As the charge control agent, a sulfonic acid group-containing copolymer obtained by copolymerizing a vinyl aromatic hydrocarbon, (meth) acrylate and a sulfonic acid group-containing (meth) acrylamide is used. The sulfonic acid group-containing copolymer may be referred to as a charge control resin. The sulfonic acid group-containing copolymer is sufficiently colorless to obtain a color toner. Copolymerizing a sulfonic acid group-containing (meth) acrylamide with the sulfonic acid group in the copolymer, thereby using the sulfonic acid group-containing copolymer as a negatively chargeable charge control agent Can. The copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide monomer unit in the sulfonic acid group-containing copolymer is required to be in the range of 0.8 to 6.0% by mass, preferably 1 It is in the range of 0.5 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. When the copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide is less than 0.8% by mass, the negative charge imparting effect is small, and conversely, when it exceeds 6.0% by mass, droplets of the organic solvent composition The dispersion stability is lowered, and a polymerized toner having a uniform particle diameter can not be obtained. In addition, even if the copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide is too small or too large, the environmental stability of the image quality is deteriorated.
In the present invention, the sulfonic acid group also includes its salt (sulfonic acid group).

The copolymerization ratio (% by mass) of the sulfonic acid group-containing (meth) acrylamide monomer unit in the sulfonic acid group-containing copolymer is a so-called preparation when the sulfonic acid group-containing copolymer is synthesized and used The proportion by weight, that is, the mass of the sulfonic acid group-containing (meth) acrylamide used can be divided by the total mass of vinyl aromatic hydrocarbon, (meth) acrylate and sulfonic acid group-containing (meth) acrylamide .
In addition, in the case where the composition of the preparation amount is unknown when using a manufactured sulfonic acid group-containing copolymer, for example, in the sulfonic acid group-containing copolymer by elemental analysis such as fluorescent X-ray analysis (XRF) The copolymerization ratio (% by mass) of the sulfonic acid group-containing (meth) acrylamide monomer unit can be calculated from the results.

  By copolymerizing a vinyl aromatic hydrocarbon, a sulfonic acid group-containing copolymer can be stably obtained. By adjusting the copolymerization ratio of the vinyl aromatic hydrocarbon and the (meth) acrylate, the glass transition temperature (Tg) of the sulfonic acid group-containing copolymer can be controlled to a desired range, whereby the heat resistance is achieved. The fixing temperature can be relatively low without impairing the storage stability. In addition, the compatibility between the sulfonic acid group-containing copolymer and the resin component of the toner can be improved by using a combination of a vinyl aromatic hydrocarbon and a (meth) acrylate, and the chargeability and other various characteristics can be improved. Can be a homogeneous toner. The copolymerization ratio (by mass) of the vinyl aromatic hydrocarbon and the (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 in the range of 5,000 to 30,000 in terms of polystyrene as measured by gel permeation chromatography (GPC) using tetrahydrofuran Is more preferably in the range of 8,000 to 25,000, still more preferably 10,000 to 20,000. When the weight average molecular weight of the sulfonic acid group-containing copolymer is too large, the size of the droplets of the organic solvent composition becomes nonuniform, and it is difficult to obtain a toner having a uniform particle diameter, which in turn results in fluidity or The heat-resistant storage stability tends to decrease, the environmental dependence of image quality and durability deteriorate, and it becomes difficult to lower the fixing temperature. When the weight-average molecular weight of the sulfonic acid group-containing copolymer is too small, the fluidity of the obtained toner becomes insufficient, the heat-resistant storage stability also decreases, and furthermore, the environmental dependence of image quality and durability tend to deteriorate. Show. Below, the raw material and manufacturing method of the sulfonic-acid-group containing copolymer used by this invention are explained in full detail.

  The vinyl aromatic hydrocarbon used in the production of the sulfonic acid group-containing copolymer is a compound (monomer) having a structure in which a vinyl group is bonded to an aromatic hydrocarbon, and specific examples thereof 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- Ethyl-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 Ren, 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 in the production of the sulfonic acid group-containing copolymer is an acrylic acid ester or a methacrylic acid ester, and specific examples thereof 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, etc .; methyl methacrylate, Ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethyl hex 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.

  As a sulfonic acid group containing (meth) acrylamide used for manufacture of a sulfonic acid group containing copolymer, 2-acrylamido 2-methylpropane sulfonic acid, 2-acrylamido n-butanesulfonic acid, 2-acrylamido-, for example n-hexanesulfonic acid, 2-acrylamido-n-octanesulfonic acid, 2-acrylamido-n-dodecanesulfonic acid, 2-acrylamido-n-tetradecanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido -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 Amide-n-decanesulfonic acid, 4-methacrylamidobenzenesulfonic acid and the like can be mentioned. 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 the respective monomer components by any polymerization method such as emulsion polymerization, dispersion polymerization, suspension polymerization, solution polymerization and the like. Among these polymerization methods, the solution polymerization method is preferable in that adjustment of the copolymerization ratio and the weight average molecular weight is easy. 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 amide, 1,1′-azobis (1-cyclohexanecarbonitrile); 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (N, N -Dimethylene isobutyl amidine), Diamine compounds such as 2,2'-azobis (N, N'-dimethylene isobutyl amidine) dihydrochloride; methyl ethyl peroxide, di-t-butyl peroxide, acetyl peroxide, dicumyl Peroxides such as peroxides, lauroyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, di-isopropylperoxydicarbonate, di-t-butylperoxyisophthalate and the like; Can.

  The use amount of the polymerization initiator can be optionally selected according to the target weight average molecular weight, but usually 0.01 to 10 parts by mass, preferably 0 based on 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 an alkali metal, butyl lithium, or a reaction product of an alkali metal and naphthalene can also be used.

  The solvent and dispersant used in solution polymerization and the like can be selected appropriately. Specifically, as hydrocarbon compounds, aromatic hydrocarbon compounds such as benzene, toluene, xylene and the like; saturated hydrocarbon organic compounds such as n-hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, nonane, decane, decalin, dodecane and the like And compounds. Examples of oxygen-containing organic compounds include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, secondary butyl alcohol, amyl alcohol, isoamyl alcohol, methyl isobutyl carbinol, 2- 2- Compounds having a hydroxyl group such as ethyl butanol, 2-ethyl hexanol, cyclohexanol, furfuryl alcohol, tetrahydrofurfuryl alcohol, ethylene glycol, hexylene glycol, glycerin and the like; 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, eth Aliphatic saturated ethers such as propyl ether, ethyl isopropyl ether, ethyl butyl ether, ethyl isobutyl ether, ethyl n-amyl ether, 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 acetic acid, acetic anhydride and butyric acid; butyl formate, amyl formate, propyl acetate, isopropyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, amyl acetate, isoamyl acetate, 2-ethylhexyl acetate, cyclohexyl acetate, butyl cyclohexyl acetate, propionyl Organic acid esters such as ethyl propionate, butyl propionate, amyl propionate, butyl butyrate, diethyl carbonate, diethyl oxalate, methyl lactate, ethyl lactate, butyl lactate, triethyl phosphate; methyl isopropyl ketone, methyl isobutyl ketone, ethyl isobutyl Ketones, ketones such as diisobutyl ketone, acetylacetone, diacetone alcohol, cyclohexanone, cyclopentanone, methylcyclohexanone and cycloheptanone; 1,4-dioxane, isophorone, furfural And other oxygen-containing organic compounds.

  The polymerization temperature and the polymerization time can be optionally selected depending on the polymerization method and the type of the polymerization initiator to be used, but usually, it is about 50 to 200 ° C., and the polymerization time is about 0.5 to 20 hours. In polymerization, commonly known additives, for example, polymerization assistants such as amines may be used in combination. The method of recovering the sulfonic acid group-containing copolymer from the system after polymerization includes a method of precipitating the copolymer by adding a poor solvent, a method of removing the solvent by steam, a method of removing the solvent by reduced pressure, heating and melting A method of removing the solvent, a method of freeze-drying, etc. are used.

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

In the production method of the present invention, aggregation of carbon black in the binder resin is achieved by separately adding and mixing an aluminum coupling agent to the organic solvent composition prior to droplet formation in the aqueous dispersion medium. Can be prevented. In addition, since it is not necessary to perform pretreatment such as coupling treatment for carbon black, it is possible to efficiently produce negatively chargeable toner.
As an aluminum coupling agent used by the manufacturing method of this invention, what is generally used in the said field can be used, For example, aluminum alcoholate, an aluminum chelate, a 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 suitably used.

The aluminum coupling agent used in the present invention is preferably in a proportion of 0.01 to 1.0 parts by mass, more preferably 0.05 to 0.8 parts by mass, with respect to 100 parts by mass of the binder resin. The aluminum coupling agent used in the present invention is preferably in a proportion of 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.
When the proportion of the aluminum coupling agent is smaller than the above range, the aggregation preventing effect of carbon black can not be sufficiently obtained.
On the other hand, if the ratio of the aluminum coupling agent is larger than the above range, the droplets are likely to be aggregated in the step of forming the droplets of the organic solvent composition, and coarse colored resin particles may be increased.

  The organic solvent used in the present invention is preferably an organic solvent capable of dissolving or dispersing the above-described binder resin, carbon black, wax, aluminum coupling agent, and charge control agent. Furthermore, the organic solvent is preferably removed when forming the colored resin particles or after forming the colored resin particles. The organic solvent is preferably volatile with a boiling point of less than 150 ° C. in terms of ease of removal. When the boiling point of the organic solvent is 150 ° C. or more, aggregation of the colored resin particles may occur 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, Dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone and the like can be mentioned. 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 alone or in combination of two or more. 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, 80-300 mass parts is more Preferably, 100 to 250 parts by mass is more preferable.

  In the present invention, an organic solvent is obtained by dispersing an organic solvent composition containing at least a binder resin, carbon black, wax, an aluminum coupling agent, and a charge control agent in an aqueous dispersion medium containing a dispersion stabilizer. Droplet formation of the composition. Although the method of droplet formation is not particularly limited, for example, (in-line type) emulsifying and dispersing machine (manufactured by Pacific Kiko Co., Ltd., trade name: cavitron), high-speed emulsification and dispersing machine (manufactured by Primix, trade name: TK homomixer MARK) It is carried out using an apparatus 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. Dispersion stabilizers include, for example, 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 polyvinyl alcohol, methyl cellulose and gelatin; water-soluble polymers such as gelatin; anionic surfactants; Organic compounds such as nonionic surfactants; amphoteric surfactants; and the like can be mentioned. The dispersion stabilizers can be used alone or in combination of two or more.

  Among the 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 resulting toner can reproduce an image clearly and is excellent in environmental stability.

2. Step of Obtaining Suspension of Colored Resin Particles In the production method of the present invention, the above 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.
The method of removing the organic solvent from the said droplet can use a well-known method. For example, there is a method in which the organic solvent composition is heated to a temperature equal to or higher than the boiling point of the organic solvent, and the temperature is maintained for a predetermined time to carry out the solvent removal.

  The colored resin particles may be used as a toner as they are or by adding an external additive, but the colored resin particles can be used as a core layer and obtained by forming a shell layer different from the core layer on the outer side thereof. It is preferable to use colored resin particles of so-called core-shell type (or also referred to as “capsule type”). The core-shell type colored resin particles balance the lowering of the fixing temperature with the prevention of aggregation during storage by covering 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 to manufacture core-shell type colored resin particle using the said droplet mentioned above, It can manufacture by a conventionally well-known method. In situ polymerization and phase separation are preferred from the viewpoint of production efficiency.

The production method of the core-shell type colored resin particles by the in situ polymerization method is described below.
In an aqueous dispersion medium in which droplets are dispersed, a polymerizable monomer (shell polymerizable monomer) for forming a shell layer and a polymerization initiator are added and polymerized to obtain core-shell type coloring Resin particles can be obtained.

  The polymerizable monomer refers to a monomer having a polymerizable functional group. The shell polymerizable monomer is polymerized to form a shell layer. It is preferable to use a monovinyl monomer as a main component of the shell polymerizable monomer. Examples of monovinyl monomers 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 Acrylates such as ethylhexyl and dimethylaminoethyl acrylate; methacrylates 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 from which a polymer having a Tg of more than 80 ° C. can be obtained alone or in combination of two or more.

  As a polymerization initiator to be used for polymerization of the polymerizable monomer for shell, metal salts of persulfates such as potassium persulfate and ammonium persulfate; 2,2'-azobis (2-methyl-N- (2-hydroxyethyl) 2.) 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, more preferably 1 to 25 parts by mass, with respect to 100 parts by mass of the shell polymerizable monomer.

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

3. Obtained Colored Resin Particles The suspension of the colored resin particles obtained as described above is subjected to filtration, washing for removing the dispersion stabilizer, dehydration and drying several times as necessary according to a conventional method. Preferably it is repeated.

  As a method of the above-mentioned washing, when using an inorganic compound as a dispersion stabilizer, dissolving and removing a dispersion stabilizer in water by addition of an acid or an alkali to suspension of colored resin particles preferable. When a colloid of a poorly water-soluble inorganic hydroxide is used as a dispersion stabilizer, it is preferable to add an acid to adjust the pH of the colored resin particle water dispersion to 6.5 or less. 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, but in particular because of high removal efficiency and small burden on manufacturing equipment. Sulfuric acid is preferred.

  Various known methods and the like can be used as the method of dehydration and filtration, and are not particularly limited. For example, centrifugal filtration, vacuum filtration, pressure filtration and the like can be mentioned. Also, the method of drying is not particularly limited, and various methods can be used.

Thus, colored resin particles are obtained.
Hereinafter, 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 size (Dv) of the colored resin particles is preferably 4 to 12 μm, and more preferably 5 to 10 μm. When Dv is less than 4 μm, the fluidity of the toner may be lowered, the transferability may be deteriorated, or the image density may be lowered. When Dv exceeds 12 μm, the resolution of the image may be reduced.

The colored resin particles preferably have a ratio (Dv / Dn) of volume average particle diameter (Dv) to number average particle diameter (Dn) of preferably 1.0 to 1.3, and more preferably 1. It is 0 to 1.2. When Dv / Dn exceeds 1.3, the transferability, the image density and the resolution may decrease. The volume average particle size and the number average particle size of the colored resin particles can be measured, for example, using a particle size analyzer (manufactured by Beckman Coulter, trade name: Multisizer) or the like.
As described above, in the present invention, a negatively chargeable toner having a narrow particle size distribution can be obtained even when manufactured 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 1.00. More preferably, it is 1.00.
When the average circularity of the colored resin particles is less than 0.96, the thin line reproducibility of printing may be deteriorated.

  In the present invention, the degree of circularity is defined as the perimeter of a circle having the same projected area as the particle image divided by the perimeter of the projected image of the particle. Further, the average degree of circularity in the present invention is used as a simple method of quantitatively expressing the shape of particles, is an index indicating the degree of unevenness of the colored resin particles, and the average degree of circularity is the colored resin particles In the case of perfect spherical shape, 1 is shown, 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, although the colored resin particles may be used as the toner as they are, the colored resin particles may be mixed and stirred with an external additive to perform external addition treatment. Preferably, an external additive is attached to the surface of the toner to form a one-component toner (developer). The one-component toner may be mixed and stirred together with carrier particles to form a two-component developer.

  The stirrer for performing the external addition treatment is not particularly limited as long as it is a stirring device capable of causing the external additive to adhere to the surface of the colored resin particles, and, for example, an FM mixer (trade name: manufactured by Nippon Coke Kogyo Co., Ltd.), Super Mixer (trade name: manufactured by Kawada Seisakusho Co., Ltd.), Q mixer (trade name: manufactured by Nippon Coke Kogyo Co., Ltd.), mechanofusion system (trade name: manufactured by Hosokawa Micron Corp.), and mechanomill (trade name: manufactured by Okada Seiko Co., Ltd.) The external addition treatment can be performed using a stirrer capable of mixing and stirring such as.

As the external additive, inorganic fine particles comprising silica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, calcium carbonate, calcium phosphate, and / or cerium oxide, etc .; polymethyl methacrylate resin, silicone resin, and / or melamine Organic fine particles made of resin etc .; Among these, inorganic fine particles are preferable, and among the inorganic fine particles, silica and / or titanium oxide are preferable, and fine particles made of silica are particularly preferable.
In addition, although these external additives can also be used independently, respectively, they can be used in combination of 2 or more types. Above all, it is preferable to use two or more types of silica having different particle sizes in combination.

  In the present invention, it is desirable to use the external additive in a proportion of usually 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 amount of external additive added is less than 0.05 parts by mass, transfer residue may occur. If the amount of the external additive exceeds 6 parts by mass, fog may occur.

5. Toner Obtained by the Manufacturing Method of the Present Invention The toner obtained through the above steps has carbon black as a colorant dispersed well, has high chargeability, is excellent in transfer efficiency and low-temperature fixability, and generates white spots. A negatively chargeable toner which provides an image having sufficient image density.
The charge control is performed by mixing an organic solvent composition with a binder resin, carbon black, a wax, an aluminum coupling agent, and a charge control agent of a copolymer having a sulfonic acid copolymer unit in a specific range. It has become possible to obtain the negatively chargeable toner of the present invention in which the aggregation of carbon black is suppressed by mixing with the aluminum coupling agent while keeping the charge amount of the toner high by the agent.

EXAMPLES The present invention will be more specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Parts and% are on a mass basis unless otherwise noted.
The test method performed in the present Example and the comparative example is 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-methylpropane sulfonic acid, and 2,2'-azobis (2,4- 2.4 parts of dimethylvaleronitrile) was charged and copolymerized at 80 ° C. for 8 hours while stirring. After completion of the reaction, the solvent was removed by lyophilization to obtain the charge control agent of Production Example 1 (the copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide monomer unit: 2.5% by mass).

Production Example 2
Production Example 1 is the same as Production Example 1 except that the amount of the monomer used for copolymerization is changed to 16 parts of 2-ethylhexyl acrylate and 1 part of 2-acrylamido-2-methylpropane sulfonic acid. The charge control agent of 2 (the copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide monomer unit: 1.0% by mass) was obtained.

[Production Example 3]
Production Example 1 is the same as Production Example 1 except that the amount of the monomer used for copolymerization is changed to 13 parts of 2-ethylhexyl acrylate and 4 parts of 2-acrylamido-2-methylpropane sulfonic acid. No. 3 charge control agent (The copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide monomer unit: 4.0% by mass, weight average molecular weight: 18,000, glass transition temperature: 57.6 ° C.) was obtained.

Production Example 4
Production Example 1 is the same as Production Example 1 except that the amount of the monomer used for copolymerization is changed to 10 parts of 2-ethylhexyl acrylate and 7 parts of 2-acrylamido-2-methylpropane sulfonic acid. The charge control agent of 4 (the copolymerization ratio of the sulfonic acid group-containing (meth) acrylamide monomer unit: 7.0% by mass) was obtained.

Production Example 5
The same procedure as in Preparation Example 1 is repeated, except that the amount of monomers used for copolymerization is changed to 16.5 parts of 2-ethylhexyl acrylate and 0.5 parts of 2-acrylamido-2-methylpropane sulfonic acid. Thus, the charge control agent of Production Example 5 (the copolymerization ratio of the 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, and 1.5 parts of t-dodecyl mercaptan as a molecular weight modifier, a polymerization initiator 4.0 parts of (Nippo Oil Co., Ltd., trade name: Perbutyl O) and 100 parts of toluene were charged into a reactor equipped with a stirring blade, and the temperature was raised to 90 ° C. to initiate a polymerization reaction. After reacting for 6 hours, the solvent was further removed by heating to 100 ° C. for 6 hours to obtain a binder resin.

  On the other hand, at room temperature, an aqueous solution in which 9.7 parts of sodium hydroxide is dissolved in 50 parts of ion-exchanged water is gradually added to an aqueous solution in which 13.9 parts of magnesium chloride is dissolved in 250 parts of ion-exchanged water under stirring. An aqueous dispersion medium of magnesium hydroxide colloid (a slightly water-soluble metal hydroxide colloid) was prepared.

100 parts of the binder resin, 0.25 parts of aluminum coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd., trade name: Prenact AL-M), carbon black (Mitsubishi Chemical Co., Ltd., trade 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 Part, 5 parts of microcrystalline wax (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 dispersing machine (manufactured by Shinmaru Enterprises, Inc., product Name: The organic solvent composition was obtained by dispersing using a dyno mill). The above organic solvent composition is charged into the above aqueous dispersion medium and stirred, and then high shear is carried out at a rotation speed of 15,000 rpm for 1 minute using an in-line type emulsification and dispersing machine (trade name: Cavitron manufactured by Pacific Kiko Co., Ltd.) Stirring formed 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 charging into a reactor equipped with a stirring blade, the temperature was raised to 75 ° C., and the solvent was removed by holding for 4 hours to obtain a suspension of colored resin particles. The temperature is further raised to 90 ° C., and 2 parts of methyl methacrylate as a polymerizable monomer for shell, and 2,2′-azobis (2-methyl-N-) as a shell polymerization initiator dissolved in 10 parts of ion-exchanged water 0.5 part of (2-hydroxyethyl) -propionamide is added, reacted for 3 hours, water cooled to stop the reaction, colored resin particles are used as a core layer, and a shell layer different from the core layer is formed on the outer side. did.
Subsequently, while stirring the suspension, sulfuric acid was added dropwise at room temperature under acid agitation until pH reached 6.5 or less. Filtration separation was performed, 500 parts of ion-exchanged water was added to the obtained solid content to make it re-slurry, and water washing treatment (washing, filtration and dehydration) was repeated several times. Finally, filtration separation was performed, and the obtained solid content was placed in a container of a drier and dried at 40 ° C. for 24 hours.

  100 parts of dried colored resin particles, 1.0 part of hydrophobized negatively chargeable silica (manufactured by Clariant) having an average primary particle diameter of 40 nm as an external additive, negatively charged with an average primary particle diameter of 12 nm, hydrophobized 0.6 parts of water-soluble silica (manufactured by Nippon Aerosil Co., Ltd.), and using a laboratory scale high-speed stirring device (manufactured by Japan Coke Industry Co., Ltd., trade name: FM mixer) having a cooling jacket and a stirring blade The external addition treatment was carried out by mixing and stirring at a peripheral speed of 40 m / sec and an external addition treatment time of 300 seconds to obtain a negatively chargeable toner of Example 1.

Example 2
A negatively chargeable toner of Example 2 was obtained in the same manner as in Example 1 except that the mixing amount of wax was changed to 7 parts of microcrystalline wax.

[ Reference Example 3 ]
A negatively chargeable toner of Reference Example 3 was obtained in the same manner as in Example 1 except that the mixing amount of wax was changed to 7 parts of a glycerin ester mixture.

[ Reference Example 4 ]
A negatively chargeable toner of Reference Example 4 was obtained in the same manner as in Example 1 except that the amount of the wax mixed was 7 parts of paraffin wax (trade name: LUVAX 1211, manufactured by Nippon Seiyo Co., Ltd.). .

[Example 5]
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 changed to the charge control agent of Production Example 2 in Example 1.

[Example 6]
A negatively chargeable toner of Example 6 was obtained in the same manner as Example 1, except that the charge control agent of Production Example 1 was changed to the charge control agent of Production Example 3 in Example 1.

Comparative 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 in Example 1.

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

Comparative Example 3
A negatively chargeable toner of Comparative Example 3 was obtained in the same manner as in Comparative Example 1 except that the mixing amount of carbon black was 6 parts in Comparative Example 1.

Comparative Example 4
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 changed to the charge control agent of Production Example 4 in Example 1.

Comparative Example 5
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 changed to the charge control agent of Production Example 5 in Example 1.

3. Characteristic Evaluation of Toner The characteristics of the negatively chargeable toners of the above Examples and Comparative Examples were examined. The details are as follows.

(1) Image Density For measuring the image density, using a commercially available non-magnetic one-component developing type printer, a toner cartridge of a developing device was filled with toner, and then printing paper was set.
After standing for 24 hours under a normal temperature / normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%), printing was performed under the same environment with a 5% printing density.
Black solid printing (printing density 100%) was performed, and the printing density of the black solid image was measured using a reflective image densitometer (manufactured by Macbeth, trade name: RD 918).
<passing grade>
In this test, when the image density was 1.48 or more, the evaluation of the image density required for toner was regarded as pass.

(2) Resistance (volume specific resistance) (log Ω / cm)
About 3 g of colored resin particles were placed in a tableting machine with a diameter of 5 cm, and a load of about 100 kg was applied for 1 minute to prepare a test piece. By performing measurement with a dielectric loss measurement device (manufactured by Ando Electric Co., model name “TRS-10 type”) under the conditions of a temperature of 30 ° C. and a frequency of 1 kHz using the test piece, the colored resin particles The volume specific resistance was determined.
<passing grade>
In this test, when the volume specific resistance value is 10.70 (log Ω / cm) or more, the evaluation of the image density required for the toner was regarded as pass.

(3) Charge amount (μC / g)
9.5 g of the carrier and 0.5 g of the toner sample are weighed, put in a 30 cc glass bottle, rotated at 150 rpm for 30 minutes, and then blown off by a blow-off meter (trade name: TB manufactured by Kyocera Chemical Co., Ltd.) Using -203), nitrogen gas was blown at a pressure of 4.5 kPa and suctioned at a pressure of 9.5 kPa to measure the blow-off charge amount.
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 was regarded as pass.

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

(5) Minimum Fixing Temperature Toner in the developing device of the printer using a printer modified to change the temperature of the fixing roll portion of a commercially available non-magnetic one-component developing type printer (printing speed = 32 sheets / minute) After 100 g of the toner was filled in the cartridge, the printing paper was set, and the fixing test was performed as follows.
In the fixing test, a black solid (print density 100%) is printed, the temperature of the fixing roll of the modified printer is changed by 5 ° C. from 200 ° C. to a low temperature area, and the fixing rate of the toner at each temperature is measured. -Determined the relationship of retention rate. At each temperature changed by 5 ° C., the temperature was maintained for 5 minutes or more in order to stabilize the temperature of the fixing roll.
The fixing rate was obtained by peeling off the tape in the printing area of solid black (printing density 100%) and calculating from the ratio of the image density before and after the peeling of the tape. That is, assuming that the image density before tape peeling (Image Density) is ID (front) and the image density after tape peeling is ID (back), the fixing rate can be calculated by the following formula 2.
Calculation formula 2 = Fixing rate (%) = (ID (post) / ID (front)) x 100
Here, with the tape peeling operation, an adhesive tape (Sumitomo 3M Co., Ltd., trade name: Scotch Mending Tape 810-3-18) is attached to the measurement portion of the test paper, and a disc-shaped metal roll (diameter 15 cm × thickness) 2 cm, weight = 1 kg), and it is a series of operations which make it press with constant pressure and make it adhere, and then peel off adhesive tape in the direction along paper at a constant speed. Further, the image density was measured using a reflection type image densitometer (manufactured by Macbeth, trade name: RD 914). In this fixing test, the lowest fixing roll temperature at which the fixing rate is 80% or more is taken as the lowest fixing temperature of the toner.

(6) Evaluation of White Spots Using a commercially available non-magnetic one-component development type printer, after standing overnight under a normal temperature and normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%), Continuous printing is performed with a print image of 5% density from the initial stage, printing is performed with a black solid print image every 500 sheets, and the presence or absence of the occurrence of white spots is confirmed.
<passing grade>
In this test, the case where there was no white spot visually was regarded as pass (A), and the case where white spot was found was regarded as fail (F).

4. Evaluation Results Table 1 shows the composition and evaluation results of preparation amounts of the negatively chargeable toners of Examples 1 to 6 and Comparative Examples 1 to 5. In the following Table 1 and in the following description, "copolymerization ratio" means the copolymerization ratio (% by mass) of 2-acrylamido-2-methylpropane sulfonic acid unit in the sulfonic acid group-containing copolymer .

5. Summary of Toner Evaluation The toner evaluation will be discussed below with reference to Table 1.
First, the toners of Comparative Examples 1 to 3 will be examined. These are toners manufactured without using an aluminum coupling agent.
The toners of Comparative Examples 1 to 3 differ in the content of carbon black. When the carbon black content is as low as 6 parts as in Comparative Example 3, no problems are found in the resistance value, the charge amount, the transfer efficiency, the minimum fixing temperature, and the white spots, but the image density is low. It is. On the other hand, by increasing the carbon black content to 9 parts or 10 parts as in Comparative Example 1 and Comparative Example 2, the image density is improved while the resistance value and the charge amount are reduced, so that the transfer efficiency, white spots, etc. Causes printing problems.
From the above, it is possible to obtain a negatively chargeable toner which has high chargeability, is excellent in transfer efficiency and low temperature fixability, does not generate white spots, and provides an image having a sufficient image density, only by adjusting the carbon black content. It can not 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).
In the toner of Comparative Example 4, since the copolymerization ratio is too high at 7% by mass, the dispersibility of carbon black is not sufficient. As a result, the image density of the toner is as low as 1.41 and the resistance value is 10.62 ( Low as log Ω / cm). On the other hand, in the toner of Comparative Example 5, since the copolymerization ratio is as low as 0.5% by mass, the negative charge imparting effect is small, and as a result, the image density of the toner is as low as 1.42 and the absolute value of the charge amount is It is as high as 17.2 μC / g and the 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 meet the acceptance criteria of all 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 a negatively chargeable toner can be produced which has high chargeability, is excellent in transfer efficiency and low temperature fixability, does not generate white spots, and produces an image having a sufficient image density.

Claims (5)

An organic solvent composition is obtained by dispersing at least a binder resin, carbon black, a 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 process for producing a negatively chargeable toner, comprising the steps of forming droplets of an organic solvent composition by turbidizing, and distilling off the organic solvent from the droplets to obtain a suspension of colored resin particles. ,
The organic solvent composition further comprises an aluminum coupling agent ,
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 sulfonic acid group-containing (meth) acrylamide monomer a sulfonic acid group-containing copolymer copolymerization proportion is from 0.8 to 6.0% by weight of the mer units seen including, and,
The method for producing a negatively chargeable toner, wherein the organic solvent composition contains microcrystalline wax as the wax .   The method for producing a negatively chargeable toner according to claim 1, wherein the wax comprises an ester wax. According to claim 1 or 2 copolymerization ratio of the sulfonic acid group-containing sulfonic acid group-containing copolymer (meth) acrylamide monomer units characterized in that it is a 1.0 to 4.5 mass% Method of producing negatively chargeable toner. The method for producing a negatively chargeable toner according to any one of claims 1 to 3 , wherein the weight average molecular weight of the sulfonic acid group-containing copolymer is 5,000 to 30,000. The organic solvent composition according to any one of claims 1 to 4 , wherein the charge control agent is contained in an amount of 0.1 to 8.0 parts by mass with respect to 100 parts by mass of the binder resin. The manufacturing method of the negatively chargeable toner as described.