JP2012113123A - Black toner for electrostatic charge image development and production method of the toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a black toner, basically giving low-temperature fixability, as well as giving excellent hot offset resistance and high glossiness, and sufficient image density.SOLUTION: The black toner comprises toner particles comprising carbon black dispersed in a binder resin. The binder resin contains a resin (A) comprising a copolymer (A) including structural units derived from a styrene monomer and from a (meth)acrylic acid monomer, and a resin (B) comprising a copolymer (B) including structural units derived from a methacrylate monomer and from a radical polymerizable monomer having a carboxyl group, in a dispersed state of a phase comprising the resin (B) in a continuous phase comprising the resin (A). The sum of copolymerization ratios of the methacrylate monomer and the radical polymerizable monomer having a carboxyl group in the copolymer (B) is from 70 to 95 mass%. The carbon black has a dispersion diameter of 10 to 300 nm.

Description

  The present invention relates to a black toner for developing an electrostatic image (hereinafter also simply referred to as “black toner”) used for electrophotographic image formation and a method for producing the same.

  In recent years, from the viewpoint of preventing global warming, energy conservation has been studied in various fields, and efforts have been made to use low energy, such as power saving during standby, in information equipment such as image forming devices. On the other hand, studies have been made to lower the fixing temperature in the fixing process that consumes the most energy. In general, the fixing temperature refers to a surface temperature set in the heating member.

For example, in the fixing device, a technique for reducing the heat capacity of the heating member has been developed to shorten the warm-up time. Specifically, as a method for thinning the aluminum base of the heating member, A method using a film or a belt is widespread.
In such a fixing device using a heating member with a reduced heat capacity, the advantage of shortening the warm-up time can be obtained, while the surface temperature of the region corresponding to the non-image portion of the heating member is excessively increased or heated. The surface temperature of the region corresponding to the image portion in the member may be excessively lowered. In particular, when the image pattern or the size of the transfer material is changed after continuously outputting the same image, the hot offset phenomenon occurs in the area where the surface temperature of the heating member is excessively increased, and the surface temperature is excessively decreased. However, there arises a problem that the fixing strength of the formed image is lowered.
In general, as a method of suppressing the occurrence of the hot offset phenomenon, a method of introducing a high elastic component into the binder resin of the toner to be used is known. However, in the formed image, the presence of the high elastic component is known. There is a problem that high gloss cannot be obtained because the surface is not smooth.
In recent years, a fixing device using a heating member having a reduced heat capacity has been developed in a color image forming apparatus, and high glossiness has been demanded for a formed image. As a method for imparting high gloss to an image to be formed, a method using a toner binder resin having a so-called sharp melt property as a binder resin is generally used, but depending on this method, a wide fixing temperature can be obtained. There is a problem that hot offset resistance cannot be obtained in the region. In addition, by using a toner having a low softening point as a binder resin, low-temperature fixing is possible and energy saving can be realized. However, merely reducing the thermal physical properties of the toner induces a hot offset phenomenon. There is a problem. As described above, it has been difficult for conventional toners to simultaneously solve the three problems of high glossiness, low-temperature fixability, and hot offset resistance.

  As a technique for simultaneously solving some of the problems as described above, for example, Patent Document 1 and Patent Document 2 have a high melting property in order to obtain higher gloss in a toner having a low temperature fixability. The use of toner is disclosed.

  However, the toner with improved meltability has lower viscoelasticity, and the separation from the fixing member is lowered in the fixing process, resulting in a wrapping phenomenon, that is, sufficient hot offset resistance cannot be obtained. However, these techniques cannot solve the three problems of low-temperature fixability, high glossiness, and hot offset resistance at the same time, or even if it is not sufficient.

  On the other hand, in a low-temperature fixing toner that can obtain high glossiness as described above, particularly a black toner, in order to melt quickly in the fixing process, it is necessary to lower the molecular weight of the resin, and when the molecular weight is decreased, Due to the increase in molecular weight terminal, carbon black cannot be well dispersed in the resin constituting the black toner due to the influence of this molecular weight terminal, and the carbon black is present in the toner particles in an aggregated and unevenly distributed state. As a result, there is a problem that the hiding power is lowered and a sufficient image density cannot be obtained.

  In order to solve such a problem, for example, in Patent Document 3, the surface carboxylic acid amount of the resin constituting the toner is specified, and the use of carbon black whose pH is adjusted to 7 to 10 enables high glossiness. And a technique for achieving both high image density and low image density.

  However, depending on the technique of Patent Document 3, since carbon black having a pH adjusted to 7 to 10 has low wettability with water, it tends to aggregate and it is difficult to ensure dispersibility in toner particles. .

JP 2003-173044 A JP 2008-26645 A JP 2010-191343 A

  The present invention has been made in consideration of the above circumstances, and its purpose is to obtain excellent hot offset resistance and high gloss while basically obtaining low-temperature fixability. Another object of the present invention is to provide a black toner for developing an electrostatic image capable of obtaining a sufficient image density and a method for producing the same.

The black toner for developing an electrostatic charge image of the present invention is a black toner for developing an electrostatic charge image comprising toner particles in which carbon black is dispersed in a binder resin,
The binder resin includes at least a resin A composed of a copolymer A including a structural unit derived from a styrene monomer and a structural unit derived from a (meth) acrylic acid monomer, and at least a methacrylic acid ester monomer. A resin B composed of a copolymer B containing a structural unit derived from a monomer and a structural unit derived from a radically polymerizable monomer having a carboxyl group, and a phase formed from the resin B in a continuous phase formed from the resin A. It is supposed to be distributed,
The value of the copolymerization ratio of the structural unit derived from the methacrylic acid ester monomer in the copolymer B constituting the resin B and the copolymerization ratio of the structural unit derived from the radical polymerizable monomer having a carboxyl group The sum of the values is 70 to 95% by mass,
The dispersion diameter of carbon black in the toner particles is 10 to 300 nm.

In the black toner for developing an electrostatic charge image of the present invention, the copolymer A constituting the resin A contains at least a structural unit derived from styrene, a structural unit derived from n-butyl acrylate, and a structural unit derived from methacrylic acid. The glass transition point is 30 to 50 ° C., the weight average molecular weight (Mw) is 10,000 to 30,000,
The copolymer B constituting the resin B includes at least a structural unit derived from methyl methacrylate and a structural unit derived from itaconic acid, and has a glass transition point of 60 to 85 ° C. and a weight average molecular weight (Mw). Is 100,000 to 400,000,
In the toner particles, the resin B is dispersed in the form of fine particles in the continuous phase of the resin A,
The dispersion diameter of the fine particles by the resin B is preferably 10 to 70 nm.

  In the black toner for developing an electrostatic image of the present invention, the content ratio of the resin A and the resin B in the binder resin is preferably 99: 1 to 85:15 in the resin A: resin B. .

  In the black toner for developing an electrostatic charge image of the present invention, the copolymerization ratio of the structural unit derived from the methacrylic acid ester monomer in the copolymer B constituting the resin B is 63.0 to 93. It is preferably 0% by mass.

  In the black toner for developing an electrostatic charge image of the present invention, the radical polymerizable monomer having a carboxyl group preferably has a plurality of carboxyl groups.

  In the black toner for developing an electrostatic charge image of the present invention, the carbon black is preferably contained in an amount of 1 to 30% by mass with respect to the binder resin.

The method for producing a black toner for developing an electrostatic charge image according to the present invention is a method for producing a black toner for developing an electrostatic charge image comprising toner particles in which carbon black is dispersed in a binder resin.
The binder resin includes at least a resin A composed of a copolymer A including a structural unit derived from a styrene monomer and a structural unit derived from a (meth) acrylic acid monomer, and at least a methacrylic acid ester monomer. A resin B composed of a copolymer B containing a structural unit derived from a monomer and a structural unit derived from a radically polymerizable monomer having a carboxyl group, and a phase of the resin B in the continuous phase of the resin A It is supposed to be distributed,
In an aqueous medium, by performing a polymerization reaction using at least a methacrylic acid ester monomer and a radical polymerizable monomer having a carboxyl group, the fine particles of the resin B made of the copolymer B are granulated,
The total amount of the methacrylic acid ester monomer and the radical polymerizable monomer having a carboxyl group is 70 to 95% by mass of the total polymerizable monomer for forming the copolymer B. Yes,
In an aqueous medium, in the presence of the fine particles of the resin B, by performing a polymerization reaction using at least a styrene monomer and a (meth) acrylic acid monomer, the resin B made of the copolymer B Granulated composite fine particles in which the surface of the fine particles is coated with the resin A composed of the copolymer A which is incompatible with the copolymer B constituting the resin B;
In the aqueous medium, the composite fine particles and the colorant fine particles having a volume-based median diameter of 10 to 300 nm are aggregated to undergo a step of forming toner particles.

In the method for producing a black toner for developing an electrostatic charge image according to the present invention, styrene, n-butyl acrylate and methacrylic acid are used as a polymerizable monomer for forming the copolymer A constituting the resin A. The copolymer A constituting the resin A has a glass transition point of 30 to 50 ° C. and a weight average molecular weight (Mw) of 10,000 to 30,000,
As a polymerizable monomer for forming the copolymer B constituting the resin B, at least methyl methacrylate and itaconic acid are used, and the copolymer B constituting the resin B has a glass transition point of 60 to 85 ° C. The weight average molecular weight (Mw) is 100,000 to 400,000,
The dispersion diameter of the resin B fine particles is preferably 10 to 70 nm.

  In the method for producing a black toner for developing an electrostatic charge image of the present invention, the mass ratio of the resin A and the resin B in the binder resin is 99: 1 to 85:15 in the resin A: resin B. It is preferable.

  In the method for producing a black toner for developing an electrostatic charge image of the present invention, the amount of the methacrylic acid ester monomer used to form the copolymer B constituting the resin B is such that the copolymer B is used. It is preferable that it is 63.0-93.0 mass% of all the polymerizable monomers for forming.

  In the method for producing a black toner for developing an electrostatic image of the present invention, the radical polymerizable monomer having a carboxyl group preferably has a plurality of carboxyl groups.

  Furthermore, in the method for producing a black toner for developing an electrostatic charge image of the present invention, the carbon black is preferably contained in an amount of 1 to 30% by mass with respect to the binder resin.

  According to the black toner for developing an electrostatic charge image of the present invention, basically, as a binder resin, a specific resin A capable of obtaining low-temperature fixability and high glossiness and a specific resin B capable of obtaining hot offset resistance. In a phase-separated state so that both low-temperature fixability and high glossiness, or hot offset resistance are not disturbed, and carbon black is highly dispersed. Sufficient image density can be obtained.

  The reason why carbon black is dispersed with high dispersibility is that the affinity between the structural unit derived from the methacrylic acid ester forming the copolymer B constituting the resin B and the carbon black is derived from the methacrylic acid ester monomer. The surface area of the phase due to the resin B is increased by containing the specific resin A and the resin B in a phase-separated state due to the hydrogen bond between the structural unit and the carbon black surface functional group. It is considered that the dispersibility of is increased.

  Hereinafter, the present invention will be specifically described.

[Black toner]
The black toner of the present invention comprises toner particles in which carbon black is dispersed in a binder resin, and the binder resin is a structural unit derived from at least a styrene monomer and a (meth) acrylic acid type A resin A comprising a copolymer A containing a structural unit derived from a monomer, a structural unit derived from at least a methacrylic acid ester monomer, and a structural unit derived from a radical polymerizable monomer having a carboxyl group And a resin B composed of a copolymer B, and a phase formed by the resin B is dispersed in a continuous phase of the resin A. The total of the copolymerization ratio value of the structural unit derived from the monomer and the copolymerization ratio value of the structural unit derived from the radical polymerizable monomer having a carboxyl group is 70 to 95% by mass. Dispersion diameter of the carbon black in the child is characterized in that it is 10 to 300 nm.

[Resin A]
Resin A constituting the binder resin according to the black toner of the present invention is a copolymer A containing at least a structural unit derived from a styrene monomer and a structural unit derived from a (meth) acrylic acid monomer. This is a so-called styrene-acrylic resin.

Specific examples of the styrene monomer for forming the copolymer A constituting the resin A include styrene or styrene derivatives shown in the following (1).
(1) Styrene or styrene derivatives: styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert -Butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, and the like.
As the styrene monomer, styrene is preferably used.
These can be used individually by 1 type or in combination of 2 or more types.
The copolymerization ratio of the structural units derived from the styrene monomer in the copolymer A constituting the resin A is preferably 45.0 to 80.0% by mass.

Further, as the (meth) acrylic acid monomer for forming the copolymer A constituting the resin A, specifically, methacrylic acid and a methacrylic acid ester derivative shown in the following (2), and Examples thereof include acrylic acid and acrylic acid ester derivatives shown in the following (3).
(2) Methacrylic acid ester derivatives: methyl methacrylate (MMA), ethyl methacrylate (EMA), n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, methacrylic acid 2-ethylhexyl, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, and the like.
(3) Acrylic acid ester derivatives: methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, acrylic acid Stearyl, lauryl acrylate, phenyl acrylate, etc.
As the (meth) acrylic acid monomer, it is preferable to use n-butyl acrylate.
These can be used individually by 1 type or in combination of 2 or more types.
The copolymerization ratio of the structural units derived from the (meth) acrylic acid monomer in the copolymer A constituting the resin A is preferably 20.0 to 55.0 mass%.

  The copolymer A constituting the resin A is preferably one using styrene as the styrene monomer and n-butyl acrylate and methacrylic acid as the (meth) acrylic monomer.

Furthermore, the copolymer A constituting the resin A includes, in addition to the styrene monomer and the (meth) acrylic acid monomer,
(1) Olefins: ethylene, propylene, isobutylene, etc. (2) Vinyl esters: vinyl propionate, vinyl acetate, vinyl benzoate, etc. (3) Vinyl ethers: vinyl methyl ether, vinyl ethyl ether, etc. (4) Vinyl ketones: Vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone, etc. (5) N-vinyl compounds: N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, etc. (6) Vinyl compounds: vinyl naphthalene, vinyl pyridine, etc. (7) ) Acrylic acid or methacrylic acid derivative: It may be copolymerized with other copolymerizable radical polymerizable monomers such as acrylonitrile, methacrylonitrile, acrylamide and the like.
Other radically polymerizable monomers for copolymerization further include radically polymerizable monomers having substituents such as ionic dissociation groups other than carboxyl groups, such as sulfonic acid groups and phosphoric acid groups. Examples of the ionic dissociation group other than the carboxyl group include a sulfonic acid group and a phosphoric acid group.
Examples of the radical polymerizable monomer having an ionic dissociation group other than a carboxyl group include styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate, 3-chloro- Examples include 2-acid phosphooxypropyl methacrylate.
Furthermore, the resin A can also have a crosslinked structure using polyfunctional vinyls as other radically polymerizable monomers for copolymerization. Examples of the polyfunctional vinyls include divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neo Examples include pentyl glycol diacrylate.
It is preferable that the copolymerization ratio of the structural unit derived from the other copolymerizable monomer for copolymerization in the copolymer A constituting the resin A is 5% by mass or less.

The copolymer A constituting the resin A preferably has a glass transition point of 30 to 50 ° C, more preferably 35.0 to 45.0 ° C. The weight average molecular weight (Mw) is preferably 10,000 to 30,000, more preferably 20,000 to 30,000.
Since the glass transition point of the copolymer A constituting the resin A is in the above range, the state of phase separation from the phase by the resin B can be reliably obtained, and the low temperature fixability, high glossiness and hot offset resistance can be obtained. Obtained in a compatible manner. On the other hand, if the glass transition point is less than 30 ° C, sufficient hot offset resistance may not be obtained, and if the glass transition point exceeds 50 ° C, sufficient low-temperature fixability and high glossiness are obtained. There is a risk of not being able to.
Further, when the weight average molecular weight (Mw) is in the above range, a glass transition point in the above range is obtained, and a state of phase separation from the phase by the resin B is surely obtained, and low temperature fixability and high gloss are obtained. Performance and hot offset resistance can be achieved at the same time. On the other hand, if the weight average molecular weight (Mw) is too small, sufficient hot offset resistance may not be obtained, and if the weight average molecular weight (Mw) is excessive, low temperature fixability and high glossiness may be obtained. There is a possibility that it cannot be obtained sufficiently.

  The glass transition point of the copolymer A constituting the resin A is measured using a differential scanning calorimeter “DSC-7” (manufactured by PerkinElmer) and a thermal analyzer controller “TAC7 / DX” (manufactured by PerkinElmer). Is. Specifically, 5.00 mg of a measurement sample (copolymer A) is sealed in an aluminum pan “KITNO.0219-0041”, and this is set in a sample holder of “DSC-7”. Using an empty aluminum pan, heat-cool-heat temperature control was performed at a measurement temperature of 0 to 200 ° C. under measurement conditions of a heating rate of 10 ° C./min and a cooling rate of 10 ° C./min. Data on Heat is acquired, and the glass transition point is the intersection of the baseline extension before the rise of the first endothermic peak and the tangent line indicating the maximum slope between the rise of the first endothermic peak and the peak apex. As shown. 1st. The heat was raised at 200 ° C. for 5 minutes.

  Further, the polymerization average molecular weight (Mw) of the copolymer A constituting the resin A is measured by gel permeation chromatography (GPC). Specifically, using an apparatus “HLC-8220” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn + TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation), while maintaining the column temperature at 40 ° C., tetrahydrofuran (THF) was used as a carrier solvent. Flow at a flow rate of 0.2 ml / min, and dissolve the measurement sample (copolymer A) in tetrahydrofuran to a concentration of 1 mg / ml under a dissolution condition in which treatment is performed at room temperature using an ultrasonic disperser for 5 minutes. A sample solution is obtained by processing with a membrane filter having a pore size of 0.2 μm, and 10 μL of this sample solution is injected into the apparatus together with the carrier solvent described above, and detected using a refractive index detector (RI detector). Using a calibration curve obtained by measuring the molecular weight distribution using monodisperse polystyrene standard particles Is calculated. Ten polystyrenes were used for calibration curve measurement.

[Resin B]
Resin B constituting the binder resin according to the black toner of the present invention contains at least a structural unit derived from a methacrylic ester monomer and a structural unit derived from a radically polymerizable monomer having a carboxyl group It is composed of coalescence B.

Specific examples of the methacrylic ester monomer for forming the copolymer B constituting the resin B include the methacrylic ester derivatives shown in the above (2).
The methacrylic acid ester derivatives shown in the above (2) can be used singly or in combination of two or more.
It is preferable that the copolymerization ratio of the structural unit derived from the methacrylic ester monomer in the copolymer B constituting the resin B is 63.0 to 93.0% by mass.

Specific examples of the radical polymerizable monomer having a carboxyl group for forming the copolymer B constituting the resin B include those shown in the following (4).
(4) Radical polymerizable monomer having a carboxyl group: one having one carboxyl group such as methacrylic acid and acrylic acid; itaconic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, 2-pentenin diacid, Those having a plurality of carboxyl groups such as allylmalonic acid, isopropylidene succinic acid, 2,4-hexadiene diacid, acetylenedicarboxylic acid, and aconitic acid.
As the radical polymerizable monomer having a carboxyl group, it is preferable to use a monomer having a plurality of carboxyl groups. Among them, itaconic acid, maleic acid or fumaric acid is more preferable, and itaconic acid is particularly used. preferable.
These can be used individually by 1 type or in combination of 2 or more types.

  As the copolymer B constituting the resin B, methyl methacrylate is used as a methacrylic ester monomer and itaconic acid is used as a radical polymerizable monomer having a carboxyl group. A radical polymerizable monomer using ethyl methacrylate as a body and maleic acid as a radical polymerizable monomer having a carboxyl group, and a monomer having ethyl carboxyl as a methacrylate ester monomer and having a carboxyl group It is preferable that any of those using itaconic acid is used.

The value of the copolymerization ratio of the structural unit derived from the methacrylic acid ester monomer in the copolymer B constituting the resin B and the copolymerization ratio of the structural unit derived from the radical polymerizable monomer having a carboxyl group The sum of the values is 70 to 95% by mass.
When the total value of the copolymerization ratio is within the above range, the carbon black is dispersed with high dispersibility in the toner particles to obtain a sufficient image density, and high glossiness and hot offset resistance are obtained. Fully obtained. On the other hand, when this is less than 70% by mass, carbon black is unevenly distributed without being sufficiently dispersed in the toner particles, so that a sufficient image density cannot be obtained and the state of phase separation is insufficient. In addition, neither high gloss nor hot offset resistance can be obtained sufficiently. On the other hand, if it exceeds 95% by mass, the carbon black is excessively finely dispersed, so that the hiding power is reduced and sufficient image density cannot be obtained, and sufficient low-temperature fixability and high glossiness are obtained. I can't.

  Further, the copolymer B constituting the resin B is shown in the following (5-1) to (5-7) below in addition to the methacrylic acid ester monomer and the radical polymerizable monomer having a carboxyl group. Copolymerized using a radical polymerizable monomer or a radical polymerizable monomer having an ionic dissociation group other than a carboxyl group such as a sulfonic acid group and a phosphoric acid group shown in (6) below. Furthermore, it may have a crosslinked structure copolymerized using a polyfunctional vinyl monomer shown in the following (7).

(5-1) Olefin: ethylene, propylene, isobutylene and the like.
(5-2) Vinyl esters: vinyl propionate, vinyl acetate, vinyl benzoate and the like.
(5-3) Vinyl ethers: vinyl methyl ether, vinyl ethyl ether and the like.
(5-4) Vinyl ketones: vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone and the like.
(5-5) N-vinyl compound: N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone and the like.
(5-6) Vinyl compounds: vinyl naphthalene, vinyl pyridine and the like.
(5-7) Acrylic acid or methacrylic acid derivatives: acrylonitrile, methacrylonitrile, acrylamide and the like.

  (6) Radical polymerizable monomer having an ionic dissociation group other than carboxyl group: maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrenesulfonic acid, allylsulfosuccinic acid, 2-acrylamido-2-methylpropanesulfonic acid Acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxypropyl methacrylate, and the like.

  (7) Polyfunctional vinyl monomer; divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate , Neopentyl glycol diacrylate, etc.

The copolymer B constituting the resin B preferably has a glass transition point of 60 to 85 ° C, more preferably 65.0 to 80.0 ° C. Moreover, it is preferable that a weight average molecular weight (Mw) is 100,000-400,000, More preferably, it is 150,000-350,000.
When the glass transition point of the copolymer B constituting the resin B is in the above range, the phase separation state from the phase by the resin A is surely obtained, and the low temperature fixability, high glossiness and hot offset resistance are obtained. Can be obtained at the same time. On the other hand, when the glass transition point is less than 60 ° C., a phase separation state from the phase due to the resin A cannot be sufficiently obtained, and a part of them is compatible. As a result, low-temperature fixability, high glossiness and There is a possibility that the hot offset resistance cannot be sufficiently obtained, and when the glass transition point exceeds 85 ° C., the low temperature fixability and the high glossiness may not be sufficiently obtained.
Further, when the weight average molecular weight (Mw) is in the above range, a glass transition point in the above range can be obtained, and a state of phase separation from the phase by the resin A can be reliably obtained, and low temperature fixability and high gloss can be obtained. Performance and hot offset resistance can be achieved at the same time. On the other hand, when the weight average molecular weight (Mw) is too small, a phase separation state with the phase due to the resin A cannot be obtained sufficiently, and a part of them is compatible. As a result, low temperature fixability and high glossiness are obtained. And / or hot offset resistance may not be sufficiently obtained, and if the weight average molecular weight (Mw) is excessive, low temperature fixability and high glossiness may not be sufficiently obtained.

The glass transition point of the copolymer B constituting the resin B is measured as described above using the copolymer B as a measurement sample.
The polymerization average molecular weight (Mw) constituting the resin B is measured as described above using the copolymer B as a measurement sample.

The content ratio of resin A and resin B in the binder resin is preferably 99: 1 to 85:15 in terms of resin A: resin B.
If the resin A content is excessive, sufficient hot offset resistance may not be obtained, and if the resin A content is excessive, sufficient low-temperature fixability and high gloss cannot be obtained. There is a fear.

  In the toner particles according to the present invention, the fine particles of the resin B are dispersed in the resin A, and the dispersion diameter of the fine particles of the resin B is preferably 10 to 70 nm. When the dispersed diameter of the fine particles by the resin B is within this range, a sufficient image density can be obtained. On the other hand, when the dispersion diameter of the fine particles by the resin B is less than 10 nm, the hiding power may be reduced and a sufficient image density may not be obtained. Further, when the dispersion diameter of the fine particles by the resin B exceeds 70 nm, there is a possibility that sufficient image density cannot be obtained because carbon black is unevenly distributed without being sufficiently dispersed in the toner particles.

〔Carbon black〕
The carbon black contained in the black toner of the present invention is a colorant, and examples of the carbon black include furnace black, channel black, acetylene black, thermal black, and lamp black. These can be used alone or in combination of two or more.
The black toner of the present invention may contain magnetic powder such as magnetite and ferrite as a colorant together with carbon black.

Carbon black has a dispersion diameter in the toner particles of 10 to 300 nm.
When the dispersion diameter in the toner particles is in the above range, a sufficient amount of carbon black can be present in the toner particles without being unevenly distributed, so that a sufficient image density can be obtained. When the dispersion diameter in the toner particles is less than 10 nm, the hiding power is lowered and a sufficient image density cannot be obtained. If the dispersion diameter in the toner particles exceeds 300 nm, carbon black may not be sufficiently dispersed in the toner particles and unevenly distributed, so that a sufficient image density may not be obtained.

  The dispersion diameter of carbon black in the toner particles is such that after embedding the black toner in a photocurable resin, an ultra-thin slice with a set thickness of 100 nm is prepared with an ultramicrotome “EM UC6” (LEICA) at an acceleration voltage of 200 kV. The ultra-thin slice was taken with a transmission electron microscope (TEM) “2000FX” (manufactured by JEOL Ltd.) at a magnification of 10,000 times, and 100 toner particles in the cross-sectional photograph were taken into the toner particles. The carbon black particles observed in (1) are randomly measured as primary particles, the horizontal ferret diameter is calculated by image analysis, and the average value is obtained.

  The content ratio of carbon black is preferably 1 to 30% by mass, and more preferably 2 to 20% by mass with respect to the binder resin. When the carbon black content is less than 1% by mass with respect to the binder resin, the resulting black toner may be insufficient in coloring power, while the carbon black content is in the binder resin. On the other hand, when it exceeds 30% by mass, the carbon black is liberated or adhered to the carrier, which may affect the chargeability.

[Average particle size of black toner]
The average particle diameter of the black toner is preferably 3 to 9 μm, and more preferably 3 to 8 μm, for example, on a volume basis median diameter. This particle size can be controlled by the concentration of the coagulant used, the addition amount of the organic solvent, the fusing time, and the composition of the polymer, for example, when the emulsion aggregation method described later is employed.
When the volume-based median diameter is in the above range, the transfer efficiency is increased, the image quality of halftone is improved, and the image quality of fine lines and dots is improved.

  The volume-based median diameter of the toner particles is measured and calculated using a measuring device in which “Multisizer 3” (manufactured by Beckman Coulter) is connected to a computer system equipped with data processing software “Software V3.51”. Is. Specifically, 0.02 g of black toner is added to 20 mL of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing toner particles). After adding and acclimatizing, ultrasonic dispersion is performed for 1 minute to prepare a black toner dispersion, and this black toner dispersion is placed in a beaker containing “ISOTON II” (manufactured by Beckman Coulter) in the sample stand. Inject with a pipette until the displayed concentration of the measuring device is 8%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measurement apparatus, the measurement particle count is 25000, the aperture diameter is 50 μm, the frequency value is calculated by dividing the measurement range of 1 to 30 μm into 256, and the volume integrated fraction is 50 % Particle diameter is defined as the volume-based median diameter.

[Average circularity of toner particles]
The black toner of the present invention has an average circularity represented by the following formula (T) of 0.930 to 1.000 for the individual toner particles constituting the black toner from the viewpoint of improving transfer efficiency. Preferably, it is 0.950 to 0.995.
Formula (T): Average circularity = circumference of circle determined from equivalent circle diameter / perimeter of particle projection image

The black toner as described above preferably has a glass transition point of 30 to 50 ° C, more preferably 35 to 45 ° C.
Furthermore, it is preferable that a softening point is 80-110 degreeC, More preferably, it is 90-105 degreeC.

The glass transition point (Tg) of the black toner is measured by the same method as described above using the measurement sample as the black toner.
The softening point of the black toner is measured as follows.
First, in an environment of a temperature of 20 ± 1 ° C. and a relative humidity of 50 ± 5% RH, 1.1 g of black toner is put in a petri dish and left flat for 12 hours or more. Then, a molding machine “SSP-10A” (Shimadzu) Pressed with a force of 3820 kg / cm ² for 30 seconds to produce a cylindrical molded sample with a diameter of 1 cm. Then, the molded sample was subjected to an environment at a temperature of 24 ± 5 ° C. and a relative temperature of 50 ± 20% RH. Below, with a flow tester “CFT-500D” (manufactured by Shimadzu Corporation), a cylindrical die hole (with a load of 196 N (20 kgf), a starting temperature of 60 ° C., a preheating time of 300 seconds and a heating rate of 6 ° C./min) 1 mm diameter x 1 mm) from the end of preheating using a piston with a diameter of 1 cm, offset method temperature T _off measured with a melting temperature measurement method of the temperature rising method with an offset value of 5 mm _set is the softening point of the black toner.

  According to such a black toner, basically, a specific resin A that provides low-temperature fixability and high glossiness and a specific resin B that provides hot offset resistance are mutually compatible as binder resins. By containing them in a separated state, they have both low-temperature fixability and high glossiness, or hot offset resistance without interfering with each other, and carbon black is dispersed with high dispersibility. As a result, a sufficient image density can be obtained.

  The reason why carbon black is dispersed with high dispersibility is that the affinity between the structural unit derived from the methacrylic acid ester forming the copolymer B constituting the resin B and the carbon black is derived from the methacrylic acid ester monomer. The surface area of the phase due to the resin B is increased by containing the specific resin A and the resin B in a phase-separated state due to the hydrogen bond between the structural unit and the carbon black surface functional group. It is considered that the dispersibility of is increased.

[Production method of black toner]
The black toner of the present invention can be produced by various known methods. As a typical method for producing the black toner of the present invention, for example, resin particles formed in an aqueous medium containing a surfactant are aggregated and fused in an aqueous medium to produce toner particles. A method called an emulsification association method may be mentioned. Since the black toner produced by this emulsion association method is surely uniform in particle size and shape, the black toner used for digital image formation with high fine line reproducibility and fine dot image formation opportunities. As a toner, it can use especially suitably.

Specifically showing an example of the case where the black toner of the present invention is produced by an emulsion association method,
(1) A polymerization step of preparing a dispersion liquid in which resin fine particles are formed by polymerization of resin A and resin B for forming a binder resin in an aqueous medium, and the resin fine particles are dispersed;
(2) Colorant fine particle dispersion preparation step of preparing a dispersion in which colorant fine particles by a colorant containing carbon black are dispersed in an aqueous medium,
(3) an agglomeration and fusing step for aggregating and fusing resin fine particles and colorant fine particles by resin A and / or resin B in an aqueous medium to form associated particles;
(4) An aging step of adjusting the shape by aging associated particles with thermal energy,
(5) a washing step of filtering the associated particles from the associated particle dispersion (aqueous medium) and removing the surfactant from the associated particles;
(6) A drying step of drying the association particles subjected to the washing treatment to obtain a toner particle matrix,
Consisting of, if necessary,
(7) an external additive adding step of adding an external additive to the dried toner particle matrix;
Can be added.

Further, when the black toner of the present invention has a core-shell structure, between the above (4) ripening step and (5) washing step,
(4-1) Associating particles that have undergone an aging step are used as core particles, and shell resin fine particles by a resin for forming a shell layer are added to the dispersion of the core particles to form shell resin fine particles on the surface of the core particles. A shelling step in which core-shell type associated particles having a core-shell structure are formed by aggregation and fusion;
(4-2) A second aging step of aging core-shell type association particles with thermal energy to adjust the shape of the core-shell type association particles,
Other than adding these two steps, the same procedure can be used.

(1) Polymerization process In this polymerization process, resin fine particles according to the resin A and the resin B are formed, and this is subjected to an aggregation and fusion process. Specifically, resin fine particles made of resin A and resin fine particles made of resin B may be separately prepared and simultaneously subjected to an aggregation and fusion process. The composite resin fine particles encapsulated in a phase-separated state may be produced, and this may be subjected to an aggregation and fusion process.
Hereinafter, the case where the composite resin fine particles in a state in which the phase of the resin B is included in the phase of the resin A will be described.

  Specifically, for the composite resin fine particles containing the resin A and the resin B, first, resin fine particles made of the resin B are produced according to a conventional method, and then the resin A is constituted in a dispersion of the resin fine particles made of the resin B. The copolymer A can be prepared by adding a monomer solution A containing monomers to form the copolymer A and polymerizing the system in the presence of resin fine particles made of the resin B.

  Resin B is a monomer solution B containing at least a methacrylic acid ester monomer to be formed and a radically polymerizable monomer having a carboxyl group, after a polymerization initiator is added to the reaction system. Is added to the reaction system to polymerize the monomer. Specifically, after adding a water-soluble radical polymerization initiator into an aqueous medium containing a surfactant, the monomer solution B is added to advance the polymerization reaction, whereby resin fine particles by the resin B are obtained. Is produced.

  The composite resin fine particles containing the resin A and the resin B are obtained by adding a monomer solution A in which a wax is dissolved or dispersed in an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less. Energy is applied to form droplets, and then resin fine particles by resin B and a water-soluble radical polymerization initiator are added, and the polymerization reaction proceeds in the droplets existing on the surface of resin fine particles by resin B. Note that an oil-soluble polymerization initiator may be contained in the droplet. In such a polymerization process, mechanical energy is imparted and forcedly emulsified (formation of droplets) is essential. Examples of the means for applying mechanical energy include means for applying strong stirring or ultrasonic vibration energy such as homomixer, ultrasonic wave, and manton gorin.

Examples of the methacrylic acid ester-based monomer contained in the monomer solution B can include those listed above, and examples of the radical polymerizable monomer having a carboxyl group include those listed above. Can be mentioned.
In the monomer solution according to Resin B, the copolymerization ratios of the methacrylic acid ester monomer and the radical polymerizable monomer having a carboxyl group are structural units derived from the desired methacrylic acid ester monomer. And a ratio according to the mass ratio of the structural units derived from the radical polymerizable monomer having a carboxyl group.

The monomer solution A related to the resin A contains at least a styrene monomer and a (meth) acrylic acid monomer, and examples of the styrene monomer include those listed above. In addition, examples of the (meth) acrylic acid monomer may include those listed above.
Moreover, these copolymerization ratios should just be taken as the ratio according to the mass ratio of the structural unit derived from the desired styrene-type monomer, and the structural unit derived from the (meth) acrylic-acid type monomer.

  Further, the mass ratio of the monomer in the monomer solution A related to the resin A and the monomer in the monomer solution B related to the resin B is a ratio that becomes a mass ratio of the desired resin A and resin B. Just do it.

  In the present invention, the “aqueous medium” refers to a medium comprising 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of the water-soluble organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran, and alcohol-based organic solvents that do not dissolve the resulting resin are preferable.

(Dispersion stabilizer)
A dispersion stabilizer is added to the aqueous medium from the viewpoint of polymerizing the liquid droplets in a stable state in the aqueous medium and stably agglomerating and fusing the resin fine particles dispersed in the aqueous medium. It is preferable.
Examples of the dispersion stabilizer include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, Examples include barium sulfate, bentonite, silica, and alumina. Moreover, what can generally be used as surfactant, such as polyvinyl alcohol, gelatin, methylcellulose, sodium dodecylbenzenesulfonate, an ethylene oxide adduct, higher alcohol sodium sulfate, can be used as a dispersion stabilizer.

The following surfactants can also be used.
Sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, sodium 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol-6-sulfonate, ortho-carboxybenzene-azo-dimethyl Sulfonic acid salts such as aniline, sodium 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sulfonate; sodium dodecyl sulfate, sodium tetradecyl sulfate, pentadecyl sulfate Sulfate esters such as sodium and sodium octyl sulfate; fatty acids such as sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, calcium oleate Ionic surfactants such as polyethylene oxide, polypropylene oxide, combinations of polypropylene oxide and polyethylene oxide, esters of polyethylene glycol and higher fatty acids, alkylphenol polyethylene oxide, esters of higher fatty acids and polyethylene glycol, higher fatty acids and polypropylene oxide Nonionic surfactants such as esters and sorbitan esters are exemplified.
The above dispersion stabilizers and / or surfactants can be used alone or in combination of two or more as desired.

(Polymerization initiator)
As the polymerization initiator used in the polymerization step, various known oil-soluble or water-soluble polymerization initiators can be used. Specific examples of the oil-soluble polymerization initiator include the following azo or diazo polymerization initiators and peroxide polymerization initiators.
(1) Azo or diazo polymerization initiator: 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,17-azobis (cyclohexane-1) -Carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile and the like.
(2) Peroxide-based polymerization initiators: benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2, 4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- (4,4-t-butylperoxycyclohexyl) propane, tris- (t-butylperoxy) triazine, and the like.
In the case of forming resin fine particles by the emulsion association method, a water-soluble polymerization initiator can be used. Specific examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and salts thereof, and hydrogen peroxide.

[Chain transfer agent]
In the polymerization step, a commonly used chain transfer agent can be used for the purpose of adjusting the molecular weight of the resin A and / or the resin B. The chain transfer agent is not particularly limited, and examples thereof include octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, n-octyl-3-mercaptopropionic acid ester, terpinolene, carbon tetrabromide, α-methylstyrene dimer, and the like. Can be mentioned.

  The dispersion diameter of the resin fine particles of the resin B in the aqueous medium is preferably 10 to 70 nm, more preferably 30 to 70 nm in terms of volume-based median diameter. When the dispersion diameter of the resin fine particles of the resin B in the aqueous medium is within this range, a sufficient image density can be obtained. On the other hand, when the dispersion diameter of the resin fine particles of the resin B in the aqueous medium is less than 10 nm, the hiding power may be reduced and a sufficient image density may not be obtained. Further, when the dispersion diameter of the resin fine particles of the resin B in the aqueous medium exceeds 70 nm, there is a possibility that sufficient image density cannot be obtained because the carbon black is not sufficiently dispersed in the toner particles and unevenly distributed.

The volume-based median diameter of the resin fine particles of the resin B in the aqueous medium is measured using “Microtrac UPA-150” (manufactured by Nikkiso Co., Ltd.).
Specifically, first, several drops of measurement fine resin particles are dropped into a 50 ml graduated cylinder, 25 ml of pure water is added thereto, and an ultrasonic cleaner “US-1” (manufactured by asone) is used. A sample for measurement is prepared by dispersing for 3 minutes. Next, 3 mL of the measurement sample was put into a cell of “Microtrac UPA-150” (manufactured by Nikkiso Co., Ltd.), and after confirming that the value of Sample / Loading was in the range of 0.1 to 100, Measurement is performed according to the measurement conditions and solvent conditions.
-Measurement conditions-
・ Transparency (transparency): Yes
-Refractive Index (refractive index): 1.59
・ Particle Density (particle density): 1.05 g / cm ³
・ Spherical Particles (spherical particles): Yes
-Solvent conditions-
-Refractive Index (refractive index): 1.33
・ Viscosity:
High (temp) 0.797 × 10 ⁻³ Pa · s
Low (temp) 1.002 × 10 ⁻³ Pa · s

In addition to the binder resin and carbon black, the toner particles of the present invention may contain an internal additive such as a wax or a charge control agent as necessary. In this polymerization step, it is dissolved in the monomer solution A for forming the copolymer A constituting the resin A or the monomer solution B for forming the copolymer B constituting the resin B. By being dispersed, it can be introduced into the toner particles.
In addition, such an internal additive is prepared by separately preparing a dispersion of internal additive fine particles consisting of only the internal additive, and (3) the internal additive fine particles together with the resin fine particles and the colorant fine particles in the aggregation and fusion process. It can also be introduced into toner particles by agglomeration.

〔wax〕
The wax is not particularly limited. For example, polyolefin waxes such as polyethylene wax and polypropylene wax, and long-chain hydrocarbon waxes such as paraffin wax and sazol wax; trimethylolpropane tribehenate, pentaerythritol Tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerine tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitic acid, distearyl maleate Ester waxes such as ate; amide waxes such as ethylenediamine dibehenyl amide and trimellitic acid tristearyl amide; Rukiruketon wax; carnauba wax, etc. montan wax and the like.
It is preferable to use a wax having a melting point of usually 40 to 160 ° C., preferably 50 to 120 ° C., more preferably 60 to 90 ° C. By using a wax having a melting point in the above range, heat-resistant storage stability is ensured for the resulting black toner, and stable image formation can be performed even when low-temperature fixing is performed.
The content ratio of the wax is preferably 1 to 30% by mass, more preferably 5 to 20% by mass with respect to the binder resin.

[Charge control agent]
Various known compounds can be used as the charge control agent.
The content ratio of the charge control agent is usually 0.1 to 10% by mass, preferably 0.5 to 5% by mass with respect to the binder resin.

(2) Colorant fine particle dispersion preparation step The colorant fine particle dispersion can be prepared by dispersing a colorant containing carbon black in an aqueous medium. The dispersion treatment of the colorant is performed in a state where the surfactant concentration in the aqueous medium is equal to or higher than the critical micelle concentration (CMC). The disperser used for the dispersion treatment of the colorant is not particularly limited, but preferably an ultrasonic disperser, a mechanical homogenizer, a pressure disperser such as a manton gourin or a pressure homogenizer, a sand grinder, a Getzmann mill, a diamond fine mill, etc. And a medium type dispersing machine.
Examples of the surfactant used include the same surfactants as those described above.

  Carbon black used as a colorant may be used after its surface is treated with a surface modifier such as a coupling agent. Specifically, carbon black is dispersed in a solvent, a surface modifier is added to the dispersion, and the system is reacted by raising the temperature. After the reaction is completed, the carbon black is filtered and the same. After repeated washing and filtration with the solvent, carbon black treated with the surface modifier is obtained by drying and used.

The dispersion diameter of the colorant fine particles in the colorant fine particle dispersion prepared in the colorant fine particle dispersion preparing step is 10 to 300 nm, more preferably 10 to 200 nm in terms of volume-based median diameter. By preparing the colorant fine particles having such a dispersion diameter, the dispersion diameter of carbon black in the obtained black toner can be made appropriate.
The volume-based median diameter of the colorant fine particles in the colorant fine particle dispersion is measured with an electrophoretic light scattering photometer “ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)”.

(3) Aggregation / fusion process In this aggregation / fusion process, a salting out / fusion method is preferably used as a specific method for aggregating and fusing the resin fine particles and the colorant fine particles. In the agglomeration / fusion step, fine particles of internal additives such as wax fine particles and charge control agents can be agglomerated and fused together with resin fine particles and colorant fine particles, if necessary.
Here, the “salting out / fusing method” means adding a salting-out agent as an aggregating agent having a critical aggregation concentration or higher in an aqueous medium, and then the glass transition point or more of the resin fine particles according to the resin A, In addition, by heating to a temperature equal to or higher than the melting peak temperature (° C.) of these mixtures, the salting out of fine particles such as resin fine particles and colorant fine particles proceeds, and at the same time, fusion is performed in parallel to achieve a desired particle size. This is a method of stopping the particle growth by adding a coagulation terminator when it has grown, and further continuing the heating to control the particle shape as necessary.

[Salting out agent]
Examples of the salting-out agent used in the aggregation and fusion process include alkali metal salts and alkaline earth metal salts. Examples of the alkali metal constituting the flocculant include lithium, potassium, and sodium, and examples of the alkaline earth metal include magnesium, calcium, strontium, and barium. Of these, potassium, sodium, magnesium, calcium, and barium are preferable. Examples of the counter ion (anion constituting the salt) of the alkali metal or alkaline earth metal include chloride ion, bromide ion, iodide ion, carbonate ion and sulfate ion.

In the case of using the salting-out / fusion method, the time allowed to stand after addition of the salting-out agent is shortened as much as possible to quickly exceed the glass transition point of the resin fine particles related to the resin A, and the mixture is melted. It is preferable to heat to a temperature equal to or higher than the peak temperature (° C.). The reason for this is that depending on the standing time after salting out, the aggregation state of the particles may fluctuate and the particle size distribution may become unstable, or the surface properties of the fused particles may vary. This is because of concern. The time until the temperature rise is preferably less than 1 hour, and the temperature rise rate is preferably 0.25 ° C./min or more. The upper limit of the rate of temperature rise is not particularly defined, but if the temperature is raised rapidly, salting out proceeds rapidly, and there is a possibility that the problem of difficulty in controlling the particle size may occur.
Moreover, it is preferable that the addition temperature of the salting-out agent is at least the glass transition point of the resin fine particles related to the resin A. The reason for this is that when the addition temperature of the salting-out agent is equal to or higher than the glass transition point of the resin fine particles related to the resin A, it is difficult to control the particle size, although the salting out / fusion of the resin fine particles proceeds rapidly. This is because there is a concern that problems such as generation of particles having a large particle diameter may occur. A preferable range of the addition temperature of the salting-out agent is not higher than the glass transition point of the resin fine particles according to the resin A, but is generally 5 to 55 ° C, preferably 10 to 45 ° C.

(4) Ripening step The toner particle shape of the black toner can be made uniform to some extent by controlling the heating temperature in the above-described aggregation / fusion step, but in order to further make the shape uniform, an aging step is performed. .
In this aging step, by controlling the heating temperature and time, the surface of the associated particles formed with a uniform particle size and a narrow distribution is controlled to have a smooth but uniform shape. Specifically, in the agglomeration and fusion process, the heating temperature is lowered to suppress the progress of fusion between the resin fine particles to promote the leveling. In this aging process, the heating temperature is lowered and the time is reduced. And the associated particles are controlled to have a desired average circularity, that is, a surface having a uniform shape.

(4-1) Shelling Step The shelling step that is performed when producing toner particles having a core-shell structure is a step in which aggregation of resin fine particles and fusion of the shell layer proceed simultaneously. In this shelling step, the resin particles for forming the shell layer are added to the dispersion liquid of the associating particles that become the core particles, and the shell resin fine particles are aggregated and fused on the surface of the core particles, and the core The surface of the particles is covered with a shell layer to form associated particles.
Specifically, the dispersion of the core particles is added to the dispersion of the shell resin particles while maintaining the temperature in the aggregation, fusion process, and aging process, and the shell resin is slowly added over several hours while continuing the heating and stirring. By agglomerating and fusing the fine particles on the surface of the core particles, the surface of the core particles is coated with a shell layer having a thickness of 100 to 300 nm to form associated particles. The heating and stirring time is preferably 1 to 7 hours, particularly preferably 3 to 5 hours.

(4-2) Second ripening step After carrying out the shelling step, a stop agent such as sodium chloride is added to stop the particle growth when the associated particles reach a predetermined particle size, and then the core particles By continuing heating and stirring for several hours in order to fuse the shell resin fine particles adhering to the particles, rounded and uniform shaped associated particles are formed.
In the case of producing a black toner having a core-shell structure, the shape of the associated particles formed can be changed to the true sphere direction by setting the time of the second aging step longer or setting the aging temperature higher. Can be controlled.

(5) Washing step In this washing step, first, the associated particle dispersion is cooled (rapidly cooled). This cooling process is performed at a cooling rate of 1 to 20 ° C./min, for example. The specific method of the cooling treatment is not particularly limited, and a known method such as a method of cooling by introducing a refrigerant from the outside of the reaction vessel, a method of cooling by directly introducing cold water into the reaction system, or the like. Can be illustrated.
Next, the associated particle dispersion liquid that has been subjected to the cooling treatment is subjected to solid-liquid separation, and the solid-liquid separated association particles are washed. That is, a solid-liquid separation process is performed in which the associated particles are solid-liquid separated from the dispersion liquid of the associated particles cooled to a predetermined temperature by the cooling process, and the toner cake of the associated particles formed by solid-liquid separation (in a wet state) Adhesives such as surfactants and salting-out agents are removed from an aggregate of agglomerated aggregated particles). A typical example of the solid-liquid separation process is a filtration process, and a specific method of the filtration process is, for example, a vacuum filtration method using a centrifugal separation method or Nutsche, a filtration method using a filter press or the like. Etc. can be used.

(6) Drying Step In this drying step, the washed toner cake is crushed and dried to obtain dried association particles, that is, toner base particles. Examples of dryers that can be used in this step include known drying processors such as spray dryers, vacuum freeze dryers, and vacuum dryers, stationary shelf dryers, mobile shelf dryers, and fluidized bed dryers. Machine, rotary dryer, stirring dryer and the like. The water content of the dried association particles is preferably 5% by mass or less, and more preferably 2% by mass or less.
In addition, when the aggregated particle | grains by which the drying process was carried out aggregated with the weak attractive force between particles, the aggregate can also be disintegrated. Specific examples of the crushing apparatus include mechanical crushing apparatuses such as a jet mill, a Henschel mixer, a coffee mill, and a food processor.

(7) External additive addition step This external additive addition step is a step of preparing toner particles by adding and mixing external additives as necessary to the dried toner base particles.
The toner base particles prepared through the steps up to the drying step can be used as toner particles as they are, but from the viewpoint of improving charging performance, fluidity, or cleaning properties as black toner, It is preferable to add known inorganic fine particles or organic fine particles, or a lubricant as an external additive.

Preferred inorganic fine particles include inorganic fine particles made of silica, titania, alumina, strontium titanate, or the like.
If necessary, these inorganic fine particles may be hydrophobized.
Specific examples of commercially available silica fine particles include “R-805”, “R-976”, “R-974”, “R-972”, “R-812”, “R” manufactured by Nippon Aerosil Co., Ltd. -809 "," HVK-2150 "," H-200 "manufactured by Hoechst," TS-720 "," TS-530 "," TS-610 "," H-5 "," MS "manufactured by Cabot −5 ”and the like.
Examples of the titania fine particles include “T-805” and “T-604” manufactured by Nippon Aerosil Co., Ltd., “MT-100S”, “MT-100B”, “MT-500BS”, and “MT-600” manufactured by Teica. ”,“ MT-600SS ”,“ JA-1 ”,“ TA-300SI ”,“ TA-500 ”,“ TAF-130 ”,“ TAF-510 ”,“ TAF-510T ”manufactured by Fuji Titanium, Idemitsu “IT-S”, “IT-OA”, “IT-OB”, “IT-OC” and the like manufactured by Kosan Co., Ltd. may be mentioned.
Examples of the alumina fine particles include “RFY-C” and “C-604” manufactured by Nippon Aerosil Co., Ltd. and “TTO-55” manufactured by Ishihara Sangyo Co., Ltd.

  As the organic fine particles, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. Specifically, homopolymers such as styrene and methyl methacrylate and organic fine particles of these copolymers can be used.

  The lubricant is used for the purpose of further improving the cleaning property and transferability. Examples of the lubricant include zinc stearate, salts of aluminum, copper, magnesium, calcium, and zinc oleate. Of higher fatty acids, such as salts of manganese, iron, copper, magnesium, zinc of palmitic acid, salts of copper, magnesium, calcium, zinc of linoleic acid, salts of calcium, zinc of ricinoleic acid, salts of calcium, etc. Metal salts are mentioned.

Various external additives may be used in combination.
The total amount of these external additives is preferably 0.1 to 10.0% by mass in the black toner.
Examples of the method of adding the external additive include a method of adding using various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.

(Developer)
The black toner of the present invention can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer.
When black toner is used as a two-component developer, the mixing amount of the black toner with respect to the carrier is preferably 2 to 10% by mass.
A mixing device for mixing the black toner and the carrier is not particularly limited, and examples thereof include a Nauter mixer, a W cone, and a V-type mixer.

As the carrier, it is preferable to use a ferrite carrier having a volume-based median diameter of 10 to 60 μm and a saturation magnetization value of 20 to 80 emu / g. By using such a carrier having a small particle diameter and a low saturation magnetization value, the magnetic brush on the developing sleeve becomes soft, and an image with good sharpness can be formed.
The volume-based median diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.
The saturation magnetization of the carrier is measured by “DC magnetization characteristic automatic recording device 3257-35” (manufactured by Yokogawa Electric Corporation).

  Further, as the carrier, it is preferable to use a coated carrier in which magnetic particles are used as a core material (core) and the surface thereof is coated with a resin. The resin used for coating the core material is not particularly limited, and various resins can be used. For example, for a black toner configured as a positively charged one, a fluorine-based resin, fluorine-acrylic acid is used. Resin, silicone resin, modified silicone resin, etc. can be used, and in particular, a condensation type silicone resin is preferably used. For example, for black toner constituted as a negatively charged one, styrene -Use of acrylic resins, mixed resins of styrene-acrylic resins and melamine resins and cured resins thereof, silicone resins, modified silicone resins, epoxy resins, polyester resins, urethane resins, polyethylene resins, etc. Among them, among them, a mixed resin of styrene-acrylic resin and melamine resin and its cured resin, It is preferable to use a condensation type silicone resin.

  When the black toner of the present invention is used as a two-component developer, a charge control agent, an adhesion improver, a primer treatment agent, a resistance control agent, etc. are further added to the black toner and carrier as necessary. Thus, a two-component developer can be formed.

(Image forming method)
The black toner of the present invention can be used in a general electrophotographic image forming method.

  As mentioned above, although embodiment of this invention was described concretely, embodiment of this invention is not limited to said example, A various change can be added.

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto.
[Black toner production example 1]
(1) Production of resin fine particles A1B1 (a) First stage polymerization (formation of resin fine particles [B1])
6.5 parts by mass of an anionic surfactant (sodium dodecylbenzenesulfonate: SDS) was dissolved in 3200 parts by mass of ion-exchanged water in a reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introduction device. The agent solution was prepared, and the temperature was raised to 80 ° C. while stirring at a rotational speed of 230 rpm under a nitrogen stream. After adding 9.0 parts by mass of potassium persulfate (KPS),
n-Butyl acrylate 132 parts by weight Methyl methacrylate 628 parts by weight Itaconic acid 40 parts by weight A monomer solution was added dropwise over 3 hours. After the completion of the dropping, the liquid temperature is maintained at 78 ° C. for 1 hour to advance the polymerization reaction, whereby resin fine particles [B1] comprising the copolymer [B1] produced from the three polymerizable monomers are obtained. A dispersed resin fine particle dispersion [B1] was prepared.
The total use ratio of methyl methacrylate and itaconic acid in the copolymer [B1] constituting the resin fine particles [B1] was 83.5 with respect to the total polymerizable monomers used for producing the resin fine particles [B1]. It was mass%.
The copolymer constituting the resin fine particles [B1] had a weight average molecular weight (Mw) of 180,000, a glass transition point of 65 ° C., and a dispersion diameter of 40 nm.
(B) Second-stage polymerization A surfactant solution was prepared by dissolving 2 parts by mass of an anionic surfactant (polyoxy (2) dodecyl ether sulfate sodium salt) in 1100 parts by mass of ion-exchanged water.
Separately, in a flask equipped with a stirring device,
Styrene 230 parts by weight n-butyl acrylate 103 parts by weight Methacrylic acid 19 parts by weight n-octyl mercaptan 4 parts by weight Paraffin wax “WBM-1” After 190 parts by weight, the mixture was heated to 85 ° C. Prepared.
After the surfactant solution is heated to 90 ° C., 75 parts by mass of the resin fine particle dispersion [B1] (in terms of solid content) and the monomer solution are added, and a mechanical disperser having a circulation path A dispersion was prepared by mixing and dispersing for 4 hours using “CLEAMIX” (manufactured by M Technique Co., Ltd.), and 15 parts by mass of potassium persulfate (KPS) was dissolved in 211 parts by mass of ion-exchanged water. A polymerization initiator solution was added, and the mixture was stirred at a liquid temperature of 90 ° C. for 2 hours to advance the polymerization reaction, thereby producing a resin fine particle dispersion [a1B1].
(C) Third-stage polymerization A polymerization initiator solution in which 7 parts by mass of potassium persulfate (KPS) is dissolved in 184 parts by mass of ion-exchanged water is added to the resin fine particle dispersion [a1B1]. Set the temperature to 80 ° C.
Styrene 415 parts by mass n-butyl acrylate 156 parts by mass n-octyl mercaptan 7.5 parts by mass A monomer solution was added dropwise. After completion of the dropping, the mixture was stirred for 2 hours at the above temperature to advance the polymerization reaction, and then the liquid temperature was cooled to 28 ° C.
As described above, in the presence of the copolymer [B1], the styrene monomer and the (meth) acrylic acid monomer are polymerized to produce the copolymer [A1]. A resin fine particle dispersion [A1B1] in which resin fine particles [A1B1] having a structure in which resin fine particles [B1] made of a polymer [B1] are encapsulated in a resin [A1] made of a copolymer [A1] is prepared. did.
The content of the resin fine particles [B1] in the resin fine particles [A1B1] is 7.5% by mass.

  The copolymer [A1] obtained by performing the second-stage polymerization step and the third-stage polymerization step under the condition in which the resin fine particles [B1] are not present has a weight average molecular weight (Mw) of 20,000. The glass transition point was 40 ° C.

(2) Production of resin fine particle C1 2 parts by mass of anionic surfactant (sodium dodecylbenzenesulfonate: SDS) was added to 2900 parts by mass of ion-exchanged water in a reaction apparatus equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction apparatus. A surfactant solution was prepared by dissolving the solution in a nitrogen stream, and the liquid temperature was raised to 80 ° C. while stirring at a rotational speed of 230 rpm under a nitrogen stream. To this, 9.0 parts by mass of potassium persulfate (KPS) was added. After adding
Styrene 516 parts by mass n-butyl acrylate 204 parts by mass Methacrylic acid 100 parts by mass n-octyl mercaptan 22 parts by mass A monomer solution was added dropwise over 3 hours. After completion of the dropping, the liquid temperature is maintained at 78 ° C. for 1 hour, and the polymerization reaction proceeds to disperse the resin fine particles [C1] having a weight average molecular weight (Mw) of 10,000 and a glass transition point of 50 ° C. A resin fine particle dispersion [C1] was prepared.
(3) Preparation of Colorant Fine Particle Dispersion While stirring a solution prepared by dissolving 90 parts by mass of sodium dodecyl sulfate in 1600 parts by mass of ion-exchanged water, 229 parts by mass of the colorant “Mulul-L” (manufactured by Cabot) was gradually added. Added to. Then, a colorant fine particle dispersion [Bk] was prepared by carrying out a dispersion treatment using a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.).
The mass average particle diameter of the colorant fine particles in this colorant fine particle dispersion [Bk] was measured with an electrophoretic light scattering photometer “ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)” and found to be 110 nm.
(4) Granulation of toner particles (a) Formation of core particles In a reaction vessel equipped with a stirrer, temperature sensor, and cooling pipe,
Resin fine particle dispersion [A1B1] 430 parts by mass (solid content conversion)
Ion-exchanged water 1650 parts by weight Colorant fine particle dispersion [Bk] 150 parts by weight were added and stirred to prepare a dispersion. To this dispersion, a 25% aqueous sodium hydroxide solution was added to adjust the pH to 10.2. The resin fine particle dispersion [A1B1] in 430 parts by mass (in terms of solid content) contains 32.25 parts by mass of resin fine particles [B1] in terms of solid content.
Next, 150 parts by mass of magnesium chloride hexahydrate aqueous solution (50% by mass) was added to the stirred dispersion over 20 minutes, and then the temperature was raised to 80 ° C. over 60 minutes. The particles were aggregated and fused while being kept at 80 ° C. In this state, using “Multisizer 3” (manufactured by Beckman Coulter, Inc.), the particle size of the particles growing in the reaction vessel was measured, and the particle size of the aggregated particles was 6.5 μm in terms of volume-based median diameter. At that time, 100 parts by mass of a 25% by mass sodium chloride aqueous solution was added to stop particle growth. Then, the core particle dispersion liquid by which a core particle was disperse | distributed was obtained by performing heating stirring for 2 hours as a ripening process over 2 hours, and controlling a shape.
(B) Formation of shell layer The above core particle dispersion is kept at a liquid temperature of 83 ° C.
Resin fine particle dispersion [C1] 50 parts by mass (solid content conversion)
Was added over 20 minutes, and then an aqueous solution in which 0.7 parts by mass of magnesium chloride hexahydrate was dissolved in 4 parts by mass of ion-exchanged water was added. The resin fine particles [C1] were aggregated and fused on the surface of the particles, and then the fusion treatment was continued for 30 minutes to form a shell layer.
(C) Aging, washing, drying treatment step and external additive addition step Thereafter, 200 parts by mass of a 25% by mass sodium chloride aqueous solution was added to stop the fusion reaction, and the temperature was raised to 88 ° C. to conduct the aging treatment. It was. The particle dispersion thus formed is cooled at 4 ° C./min, washed thoroughly with ion-exchanged water at 20 ° C., and further dried at room temperature, whereby a toner having a core-shell structure. Particles [1X] were prepared.
As an external additive to this toner particle [1X],
Silica treated with hexamethylsilazane (average primary particle size 12 nm): 0.6 parts by mass Titanium dioxide treated with n-octylsilane (average primary particle size 24 nm): 0.8 parts by mass were added, and “Henschel mixer” was added. Black toner [1] was obtained by performing an external addition process using Mitsui Miike Mining Co., Ltd.
The external addition process using a Henschel mixer was performed under the conditions of a peripheral speed of a stirring blade of 35 m / second, a processing temperature of 35 ° C., and a processing time of 15 minutes.

[Black toner production examples 2 to 22]
In black toner production example 1, the type and amount of polymerizable monomer used to produce resin fine particles [B1] were changed according to Table 1, and the weight average molecular weight (Mw), glass transition as shown in Table 1 was changed. A resin particle having a point (Tg) and having a dispersion diameter as shown in Table 1 is used, and a copolymer according to Resin A obtained under the condition in which the resin fine particles [B1] are not present is shown in Table 1. Black toners [2] to [22] were obtained in the same manner except that the resin A having a weight average molecular weight (Mw) of 1 and a glass transition point (Tg) was used.

[Developer Production Examples 1 to 22]
Each of the black toners [1] to [22] is mixed with a ferrite carrier having a volume average particle diameter of 50 μm coated with a silicone resin so that the toner concentration becomes 6%, whereby two-component developers [1] to [2] [22] was prepared.

[Evaluation 1: Evaluation of dispersion diameter of carbon black]
After embedding each black toner in a photocurable resin, an ultrathin section with a set thickness of 100 nm was prepared at an acceleration voltage of 200 kV with an ultramicrotome “EM UC6” (manufactured by LEICA), and the ultrathin section was transmitted. Carbon black particles observed in the toner particles of 100 toner particles in the cross-sectional photograph taken with a scanning electron microscope (TEM) “2000FX” (manufactured by JEOL Ltd.) Were randomly measured as primary particles, the horizontal ferret diameter was calculated by image analysis, and the average value was measured as the carbon black dispersion diameter. The results are shown in Table 2.
The black toners [1] to [18] satisfy the requirements of the present invention, and the black toners [19] to [22] do not satisfy the requirements of the present invention.

[Evaluation 2: Evaluation of glossiness]
As the image forming apparatus, a commercially available multifunction machine “bishub PRO C6501” (manufactured by Konica Minolta Business Technologies) is used. The developer is introduced into the multifunction machine, and the surface temperature of the heating roller of the fixing device using the heat roller fixing method is used. The toner amount is 1.2 mg / ton on the transfer material “POD gloss coat (128 g / m ² )” (manufactured by Oji Paper Co., Ltd.) in an environment of room temperature and normal temperature (temperature 20 ° C., humidity 50% RH). A solid image of cm ² was formed. The glossiness of this solid image was measured using a gloss meter “Gloss Meter” (manufactured by Murakami Color Engineering Laboratory) with an incident angle of 75 ° with respect to a glass surface with a refractive index of 1.567. And evaluated. The results are shown in Table 2.
In addition, when the glossiness is 60% or more, there is no practical problem and it is determined to be acceptable.

[Evaluation 3: Evaluation of hot offset resistance]
As the image forming apparatus, a commercially available multifunction machine “bishub PRO C6501” (manufactured by Konica Minolta Business Technologies) is used. The developer is introduced into the multifunction machine, and the surface temperature of the heating roller of the fixing device using the heat roller fixing method is used. Was changed in increments of 5 ° C. within a range of 100 to 180 ° C., and a fixing test was performed on the following items in each environment at an ambient temperature of normal temperature (temperature 20 ° C., humidity 50% RH).
First, on a A4 coated paper “POD gloss coat (84.9 g / m ² )” (manufactured by Oji Paper Co., Ltd.), a solid belt-like image having a width of 5 cm in the direction perpendicular to the conveying direction was fixed by transverse feeding. The lower limit temperature A of the fixing temperature was confirmed based on whether or not the hot offset phenomenon occurred. Next, on the A4 coated paper “POD gloss coat (84.9 g / m ² )” (manufactured by Oji Paper Co., Ltd.), a 5 mm wide solid band image and a 20 mm wide halftone image are horizontally placed in the direction perpendicular to the conveying direction. The temperature B when the image surface is rough due to the hot offset phenomenon or the heating roller is contaminated is confirmed by feeding and conveying, and the difference between the temperature B and the lower limit temperature A is determined as a fixing temperature region, that is, a non-hot offset region. As evaluated. The results are shown in Table 2.
In addition, when a non-hot offset area | region is 65 degreeC or more, it is judged that there is no practical problem and it is a pass.

[Evaluation 4: Evaluation of image density]
As the image forming apparatus, a commercially available multifunction machine “bishub PRO C6501” (manufactured by Konica Minolta Business Technologies) was used, and the developer was introduced into this multifunction machine to form 10,000 solid black patch images. With respect to the tenth sheet, the absolute image density at 12 arbitrary positions was measured and averaged by using a reflection densitometer “RD-918” (manufactured by Macbeth), and this was evaluated as the image density. The results are shown in Table 2.
If the image density is 1.2 or more, there is no practical problem and it is determined to be acceptable.

Claims (12)

A black toner for developing an electrostatic image comprising toner particles in which carbon black is dispersed in a binder resin,
The binder resin includes at least a resin A composed of a copolymer A including a structural unit derived from a styrene monomer and a structural unit derived from a (meth) acrylic acid monomer, and at least a methacrylic acid ester monomer. A resin B composed of a copolymer B containing a structural unit derived from a monomer and a structural unit derived from a radically polymerizable monomer having a carboxyl group, and a phase formed from the resin B in a continuous phase formed from the resin A. It is supposed to be distributed,
The value of the copolymerization ratio of the structural unit derived from the methacrylic acid ester monomer in the copolymer B constituting the resin B and the copolymerization ratio of the structural unit derived from the radical polymerizable monomer having a carboxyl group The sum of the values is 70 to 95% by mass,
A black toner for developing an electrostatic charge image, wherein a dispersion diameter of carbon black in the toner particles is 10 to 300 nm. The copolymer A constituting the resin A includes at least a structural unit derived from styrene, a structural unit derived from n-butyl acrylate, and a structural unit derived from methacrylic acid, and has a glass transition point of 30 to 50. And the weight average molecular weight (Mw) is 10,000 to 30,000,
The copolymer B constituting the resin B includes at least a structural unit derived from methyl methacrylate and a structural unit derived from itaconic acid, and has a glass transition point of 60 to 85 ° C. and a weight average molecular weight (Mw). Is 100,000 to 400,000,
In the toner particles, the resin B is dispersed in the form of fine particles in the continuous phase of the resin A,
The black toner for developing an electrostatic charge image according to claim 1, wherein the dispersion diameter of the fine particles by the resin B is 10 to 70 nm.   3. The electrostatic charge image according to claim 1, wherein the content ratio of the resin A and the resin B in the binder resin is 99: 1 to 85:15 for resin A: resin B. 4. Black toner for development.   The copolymerization ratio of the structural unit derived from the methacrylic acid ester monomer in the copolymer B constituting the resin B is 63.0 to 93.0% by mass. Item 4. The black toner for developing an electrostatic charge image according to any one of Items 3.   The black toner for developing an electrostatic charge image according to claim 1, wherein the radical polymerizable monomer having a carboxyl group has a plurality of carboxyl groups.   6. The black toner for developing an electrostatic image according to claim 1, wherein the carbon black is contained in an amount of 1 to 30% by mass with respect to the binder resin. A method for producing a black toner for developing an electrostatic image comprising toner particles in which carbon black is dispersed in a binder resin,
The binder resin includes at least a resin A composed of a copolymer A including a structural unit derived from a styrene monomer and a structural unit derived from a (meth) acrylic acid monomer, and at least a methacrylic acid ester monomer. A resin B composed of a copolymer B containing a structural unit derived from a monomer and a structural unit derived from a radically polymerizable monomer having a carboxyl group, and a phase of the resin B in the continuous phase of the resin A It is supposed to be distributed,
In an aqueous medium, by performing a polymerization reaction using at least a methacrylic acid ester monomer and a radical polymerizable monomer having a carboxyl group, the fine particles of the resin B made of the copolymer B are granulated,
The total amount of the methacrylic acid ester monomer and the radical polymerizable monomer having a carboxyl group is 70 to 95% by mass of the total polymerizable monomer for forming the copolymer B. Yes,
In an aqueous medium, in the presence of the fine particles of the resin B, by performing a polymerization reaction using at least a styrene monomer and a (meth) acrylic acid monomer, the resin B made of the copolymer B Granulated composite fine particles in which the surface of the fine particles is coated with the resin A composed of the copolymer A which is incompatible with the copolymer B constituting the resin B;
An electrostatic charge image developing black characterized by undergoing a step of forming toner particles by aggregating the composite fine particles and fine particles of a colorant having a volume-based median diameter of 10 to 300 nm in an aqueous medium. Toner manufacturing method. Styrene, n-butyl acrylate and methacrylic acid are used as polymerizable monomers for forming the copolymer A constituting the resin A, and the copolymer A constituting the resin A has a glass transition point of 30 to 30. 50 ° C., weight average molecular weight (Mw) is 10,000 to 30,000,
As a polymerizable monomer for forming the copolymer B constituting the resin B, at least methyl methacrylate and itaconic acid are used, and the copolymer B constituting the resin B has a glass transition point of 60 to 85 ° C. The weight average molecular weight (Mw) is 100,000 to 400,000,
The method for producing a black toner for developing an electrostatic charge image according to claim 7, wherein a dispersion diameter of the fine particles of the resin B is 10 to 70 nm.   9. The electrostatic charge image according to claim 7, wherein a content ratio of the resin A and the resin B in the binder resin is 99: 1 to 85:15 in the resin A: resin B. 10. A method for producing black toner for development.   The amount of the methacrylic acid ester monomer used to form the copolymer B constituting the resin B is 63.0 to 63.0% of the total polymerizable monomers used to form the copolymer B. The method for producing a black toner for developing an electrostatic charge image according to any one of claims 7 to 9, wherein the amount is 93.0% by mass.   The method for producing a black toner for developing an electrostatic charge image according to any one of claims 7 to 10, wherein the radical polymerizable monomer having a carboxyl group has a plurality of carboxyl groups. . The method for producing a black toner for developing an electrostatic charge image according to any one of claims 7 to 11, wherein the carbon black is contained in an amount of 1 to 30% by mass with respect to the binder resin.