JP2006171501A - Dry toner for electrostatic image development and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dry toner having good charge stability, excellent in charge retentivity (not causing charge attenuation by leaving), having satisfactory charge stability and good image properties while using a small amount of a charge control agent, and excellent also in environmental safety, and to provide a method for manufacturing the same. <P>SOLUTION: The dry toner for electrostatic image development is obtained as follows; a nigrosine dye (A) is wet-milled to obtain a slurry (B) of the finely divided nigrosine dye having a volume average particle diameter of 0.2-2.0 μm, the slurry (B) and a resin (C) which is solid at room temperature are heated and kneaded, the solvent is removed, and the resulting resin coated nigrosine dye (D), a colorant and a binder resin and heated and kneaded. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a dry toner for developing an electrostatic charge image used for developing an electrostatic latent image in an electrophotographic copying machine, a laser beam printer or the like in which an image is formed by using an electrophotographic method, an electrostatic recording method or the like. And a manufacturing method thereof.
In particular, the present invention relates to a dry toner for developing an electrostatic image using a charge control agent that is excellent in chargeability, dispersibility, and environmental safety and is preferably used for a positively charged toner, and a method for producing the same.

 Conventionally, as a method for developing an electrostatic latent image formed on an electrostatic image carrier such as an electrophotographic photosensitive member or an electrostatic recording member, it can be roughly divided into liquid development in which fine toner is dispersed in an electrically insulating liquid. Two methods are known: a method using an agent (wet development method) and a method using a toner in which a colorant or magnetic powder is dispersed in a binder resin (dry development method). In the dry development method, a method using a two-component developer composed of carrier particles and a toner and a method using a one-component developer composed of only a toner (usually magnetic toner) are known.

  The dry toner for electrostatic image development used in these dry development methods usually uses a styrene resin or a polyester resin as a binder resin, kneaded colorants such as dyes and pigments, and cooled, Manufactured through pulverization and classification. The particle size of the electrostatic toner for developing an electrostatic image is usually an average particle size of about 1 to 30 μm. In the case of magnetic toner, magnetic powder such as magnetite is further used. Further, as carrier particles used in the two-component developer, iron powder, ferrite, magnetite, etc., which are coated with a hydrophobic resin as required, are used.

  The dry toner for developing an electrostatic charge image as described above is required to hold a positive or negative charge depending on the polarity of the electrostatic latent image to be developed. In order to retain the charge in the dry toner for developing an electrostatic image, it is possible to use triboelectric charging properties such as a binder resin as a toner component, but this alone usually has a small charge amount and the polarity is not stable. The image obtained by development tends to cause fogging and is unclear. For this reason, a material called a charge control agent is generally added to the toner in order to impart desirable charging characteristics to the toner.

As is well known, a nigrosine dye is used as a charge control agent for obtaining good positive chargeability. Nigrosine dye has a stable positive chargeability and is used as a charge control agent for many positively chargeable toners. (For example, see Non-Patent Document 1)
It has also been studied to improve the chargeability and image characteristics by using a nigrosine dye pulverized to a mean particle size of 5 μm or less by pulverizing the nigrosine dye in a dry pulverizer. (For example, see Patent Documents 1, 2, 3, etc.)
However, in the conventional pulverization of nigrosine dye by the dry pulverization method, there is a limit to the particle size distribution that can be pulverized, and the average particle diameter is limited to about 1 to 2 μm. Further, it is difficult to make the particle size distribution sharp and uniform, and coarse particles exceeding 3 μm remain, and there is substantially no effect of an average particle size of 1 to 2 μm. It is difficult to do so.

In addition, a charge control agent (specifically, an azo-based metal complex) is pulverized to 0.7 μm or less by a wet method, and good image characteristics can be obtained by fixing the pulverized particles to the toner particle surface. It is disclosed. (For example, see Patent Document 4)
However, in the case of internal addition in the toner, agglomeration occurs due to the presence of ultrafine powder (particles of 0.2 μm or less), and uniform dispersion is difficult.

  Also, since nigrosine dyes frequently use aniline and nitrobenzene as raw materials in the production process, aniline remains in the nigrosine dye even after production. Actually, 2000 ppm or more of unreacted aniline remains in the nigrosine base.

In the examination so far, we have produced a favorable result by making a nigrosine dye that reduces aniline in the nigrosine dye, but it is difficult to reduce the particle size, and it is not always satisfactory as a charge control agent for toner It could not be said. (For example, see Patent Documents 5 and 6)
In addition, as a toner particle size reduction is being studied, there is a need for a charge control agent having a particle size smaller and finer than the present state. Even if the toner is not a small particle size toner, it can be expected that the charge control agent has a small particle size and has good charging stability and an effect of preventing charge attenuation. It is also preferable to use a charge control agent that can reduce the amount added and give sufficient charge.

“Basics and Applications of Electrophotographic Technology” Corona, June 15, 1988, P.480 JP-A-60-118851 Japanese Unexamined Patent Publication No. 1-2-19848 Japanese Patent Laid-Open No. 3-15767 Japanese Patent Laid-Open No. 2002-23418 JP-A-6-230611 JP 2002-311652 A

 As described above, the nigrosine dye is an excellent charge control agent for positive charging that has been widely used conventionally, but has various problems. It is desired to solve these problems and to have a sufficient charge control effect with a small amount of use, environmental safety, good charge stability, charge retention, and a small amount.

  In view of such a current situation, an object of the present invention is to provide a dry toner having excellent charge stability and charge retention (no charge decay due to standing).

  Another object of the present invention is to provide a dry toner having sufficient charge stability and good image characteristics with the use of a small amount of a charge control agent.

  Another object of the present invention is to provide a dry toner excellent in environmental safety.

  As a result of intensive studies, the inventors of the present invention wet-pulverized the nigrosine dye (A) to obtain a refined nigrosine dye slurry (B) having a specific average particle size, and then the slurry (B) and a solid at room temperature. It has been found that the above object can be achieved by a dry toner using a resin-coated nigrosine dye (D) obtained by removing the solvent while heating and kneading the resin (C) as a charge control agent, and has led to the present invention. is there.

That is, the present invention relates to the following inventions (1) to (6).
(1) The nigrosine dye (A) is wet-pulverized to obtain a finely divided nigrosine dye slurry (B) having a volume average particle size of 0.2 to 2.0 μm, and then the slurry (B). And a resin-coated nigrosine dye (D) obtained by removing the solvent after heating and kneading the resin at room temperature and solid resin (C), a coloring agent, and a binder resin. This is a dry toner for developing charge images.
(2) The dry toner for developing electrostatic images according to (1), wherein the aniline content in the resin-coated nigrosine dye (D) is 500 ppm or less.
(3) The dry toner for developing electrostatic images according to (1) or (2), wherein the solvent for wet pulverization is a lower alcohol having 3 or less carbon atoms.
(4) The dry toner for developing electrostatic images according to any one of (1) to (3), wherein the wet pulverization apparatus is a medium stirring mill.
(5) The dry toner for developing electrostatic images according to any one of (1) to (4), wherein the nigrosine dye (A) is based on nigrosine.
(6) The nigrosine dye (A) is wet pulverized to obtain a finely divided nigrosine dye slurry (B) having a volume average particle size of 0.2 to 2.0 μm, and then the slurry (B). And a resin-coated nigrosine dye (D) obtained by removing the solvent after heating and kneading the resin at room temperature and solid resin (C), a coloring agent, and a binder resin. This is a method for producing a dry toner for charge image development.

The dry toner for developing an electrostatic charge image of the present invention uses a resin-coated nigrosine dye containing a nigrosine dye that has been refined by wet pulverization and obtained by a flushing method as a charge control agent. Dispersed and distributed, and good positive chargeability and charge stability can be obtained. In addition, since the particle size is much smaller than that of the conventionally used nigrosine dye, it is possible to obtain a sufficient positive charge even with a small addition amount. Furthermore, the nigrosine particles are refined, sized and dispersed as uniform particles in the resin through wet pulverization and flushing treatments, contributing to uniform dispersibility and compoundability in the toner. It is.
In addition, after pulverization in a wet process, flushing treatment can be performed to efficiently remove aniline, which is an unreacted raw material remaining in nigrosine, and is a preferable charge control agent from the viewpoint of environmental safety. Is. Furthermore, by making finer and reducing aniline, it is possible to impart a stable positive charge property to the toner that has a quick rise in charge and no charge decay due to long-term standing.

Hereinafter, the present invention will be described in more detail.
As described above, the resin-coated nigrosine dye (D), which is a charge control agent for the dry toner for developing electrostatic images according to the present invention, is wet pulverized using the nigrosine dye (A) as a raw material and has a volume average particle size of 0. It is obtained by removing the solvent after heat-kneading the obtained slurry (B) and the normal temperature solid resin (C) after being refined to 2 to 2.0 μm.
In the present invention, the main purpose of performing wet pulverization is to make the nigrosine dye fine and homogenous and to greatly improve the charge imparting ability as a charge control agent. In addition, the coarse particles are further reduced to improve the dispersibility and blendability of the charge control agent in the binder resin. Further, a finely divided nigrosine dye slurry and a room temperature solid resin are heat-kneaded, flushed to remove the solvent, thereby obtaining a resin-coated nigrosine dye in which the finely divided nigrosine dye is preferably dispersed, and nigrosine. The purpose is to remove the aniline remaining in the dye.

The nigrosine dye (A) as a raw material of the resin-coated nigrosine dye (D) preferably used in the dry toner for developing an electrostatic charge image of the present invention is a nigrosine base or a composition containing a nigrosine base obtained by the following production method. Certain nigrosine dyes, or commercially available nigrosine-based products or products of nigrosine dyes that are compositions containing nigrosine bases can be used.
In the present invention, it is important to refine the nigrosine dye (A) through wet pulverization, and since wet pulverization is performed, it is essential to have excellent water resistance and oil resistance as raw materials. It is necessary to use a composition containing a base and a nigrosine base. Since the crude hydrophilic nigrosine that has not been made into a base has high solubility in water and lower alcohols, it is not only difficult to refine by wet grinding but also has poor water resistance and oil resistance. It is not preferable for use as a control agent.

The nigrosine dye (A) used in the dry toner for developing an electrostatic charge image of the present invention reacts by oxidizing aniline and aniline hydrochloride as raw materials with nitrobenzene in the presence of iron chloride, iron and hydrochloric acid at 160 to 180 ° C. After the crude nigrosine is obtained by neutralization, an aqueous alkaline solution is added to neutralize, the dye aniline phase is separated, then base-treated with alkali, washed with water, filtered, dried and pulverized. is there. When the nigrosine dye is made into a base, it becomes insoluble in water, which is preferable for wet grinding. In addition, when the base treatment is performed, it is preferable that aniline is added again to the crude nigrosine together with the alkaline aqueous solution because the size of the nigrosine particles is adjusted.
The nigrosine dye (A) is preferably pulverized to a volume average particle size of 5 to 30 μm in order to perform wet pulverization efficiently. The average particle size of the nigrosine dye (A) before wet pulverization was measured using a multisizer (aperture 100 μm) manufactured by Beckman Coulter.

  In the present invention, as the nigrosine dye (A), a commercially available nigrosine base or nigrosine dye can be used as a raw material. Specifically, it contains a compound classified as Solvent Black 7, Bontron N-01, N-04, N-07, Nigrosine Base EX manufactured by Orient Chemical Co., Ltd. CHUO CCA-1, CCA-2 manufactured by Chuo Synthetic Chemical Co., Ltd. And CCA-3.

The wet pulverizer that can be used to obtain the finely divided nigrosine dye slurry (B) uses a pulverizing medium, and includes a container driving medium mill and a medium agitating mill. Examples of the container-driven medium mill include a rolling ball mill, a vibrating ball mill, a planetary ball mill, and a centrifugal fluidizing mill, and examples of the medium agitating mill include a tower pulverizer, a stirring tank mill, a flow tank mill (horizontal type, Vertical type), annular mill and the like.
In any of the above apparatuses, it is possible to refine the nigrosine dye by wet pulverization, but among them, it is preferable to use a medium stirring mill from the viewpoint of productivity, pulverization ability, control of particle size distribution, etc. Among these, it is preferable to use a wet pulverizer classified as a horizontal distribution tank mill that is filled with sealed micro-beads and used as a medium (medium) for precise wet pulverization and dispersion.
Specific examples include WAB (Shinmaru Enterprises), Dynomill (DYNO-MILL), and the like. This is because in a horizontal wet pulverizer, the dispersion medium is hardly affected by gravity, so that a uniform distribution close to ideal can be obtained in the pulverizer. In addition, since it has a completely sealed structure, there is no loss of balance due to foaming or solvent evaporation, and stable pulverization is possible.

 In the wet pulverizer used in the present invention, the major factors that determine the pulverizability include the type of pulverization media, the particle size of the pulverization media, the filling rate of the dispersion media in the pulverizer, the type of agitator disk, the solution of the sample to be pulverized Concentration, type of solvent, etc. Among these, the type of pulverized media and the particle size of the media greatly contribute to pulverization.

The types of grinding media include glass beads (SiO ₂ 70-80%, NaO 12-16%, etc.), zircon beads (ZrO ₂ 69%), depending on the viscosity, specific gravity, grinding and dispersion required particle size of the charge control agent. , SiO ₂ 31%), zirconia beads (ZrO ₂ 95% or more), alumina (Al ₂ O ₃ 90% or more), titania (TiO ₂ 77.7%, Al ₂ O ₃ 17.4%), steel balls, etc. However, it is preferable to use zirconia beads or zircon beads in order to obtain good grindability.
The particle diameter (diameter) of the pulverization media can be used in the range of 0.1 mm to 3.0 mm, but in particular, the range of 0.3 to 1.4 mm is preferable. If it is smaller than 0.1 mm, the load in the pulverizer increases, and the nigrosine dye melts due to heat generation, making pulverization difficult, and if it is larger than 3.0 mm, sufficient pulverization cannot be performed. . The filling rate of the dispersion medium is preferably 60 to 85%. If it exceeds 85%, the load in the pulverizer increases, the nigrosine dye melts due to heat generation, making pulverization difficult, and if it becomes 60% or less, the pulverization efficiency decreases. Refinement becomes difficult. When the nigrosine concentration in the slurry is high (concentration of 40 to 50%), the filling rate is preferably 60 to 70% by weight.

 An agitator disk inside the wet pulverizer preferably used in the present invention is also important for controlling the pulverization property. The peripheral speed of the disk is preferably 4 to 16 m / s, and if it is less than 4 m / s, it takes time to grind. If it is greater than 16 m / s, heat is generated due to contact with the grinding media. As a result, the nigrosine dye is fused, which is not preferable. As a material of the agitator disk, hardened steel, stainless steel, alumina, zirconia, polyurethane, polyethylene, engineering plastic, and the like can be used. Among them, zirconia is preferable.

  Examples of the material of the grinding cylinder on the inner wall of the wet pulverizer include special hardened steel, stainless steel, alumina, zirconia, ZTA, glass, and polyethylene. Among them, it is preferable to use zirconia reinforced alumina ceramics called ZTA.

The solvent used in the wet pulverization is preferably a solvent that is insoluble in the nigrosine dye and is capable of dissolving aniline and nitrobenzene. Specifically, methanol, ethanol, propanol, isopropyl alcohol, butanol, and the like are used. It is preferable to use a lower alcohol having 3 or less carbon atoms. On the other hand, when an alcohol having 4 or more carbon atoms is used, the nigrosine dye may dissolve, which is not preferable.
Further, in the wet pulverization, the solvent functions as a pulverization aid, and a lower alcohol having 3 or less carbon atoms is preferable as the pulverization aid.

The nigrosine dye (A) is preferably added at a ratio of about 5 to 50% with respect to 100 parts by weight of the solvent to prepare a slurry and pulverize it. If the concentration of nigrosine dye in the slurry is less than 5%, the pulverization efficiency is poor, and if it exceeds 50%, the load of pulverization increases even if the filling rate of the media is lowered. Fusion may occur.
Here, the slurry in which the nigrosine dye (A) is dispersed is put into a wet pulverizer and pulverized. At this time, the temperature in the pulverizer is cooled to prevent the viscosity of the nigrosine dye slurry from increasing and the fluidity from decreasing. It is preferable to keep it at 40 ° C. or lower. If the pulverization is performed at a temperature exceeding 40 ° C., the nigrosine dye in the pulverizer aggregates, which is not preferable.

In the wet pulverization, the liquid at the time of pulverization plays a role of a pulverization aid, and has a very excellent pulverization property as compared with the dry pulverization conventionally performed. By performing wet pulverization, it is possible to reduce the particle size compared to dry pulverization, and the particle size distribution is uniform and sharp. Further, by having a sizing action, the shape of the particles becomes uniform, and it becomes possible to uniformly disperse the toner.
The reason why wet pulverization shows such a favorable effect compared with dry pulverization is that the liquid wets the surface of the nigrosine dye particles, thereby reducing the surface energy of the particle surface and decreasing the particle strength, and the liquid There are two factors that suppress the mutual aggregating action and keep the particles pulverized in the system in a uniform dispersed state, thereby improving the efficiency of pulverization.

 The nigrosine dye (A) is finely pulverized through a wet pulverizer to obtain a finely divided nigrosine dye slurry (B). And the volume average particle diameter of the refined nigrosine dye in the slurry (B) is preferably in the range of 0.2 to 2.0 μm, more preferably in the range of 0.3 to 1.8 μm. Further, in consideration of obtaining an optimum charging property, the range is 0.8 to 1.8 μm. If it is smaller than 0.2 μm, aggregation occurs and poor dispersion occurs. On the other hand, if it is larger than 2.0 μm, it becomes difficult to obtain good uniform and stable charging characteristics, and the effect cannot be obtained. And it is preferable not to have a particle | grain exceeding 3 micrometers substantially. By performing the pulverization by wet pulverization, uniform pulverization can be performed, so that the particle size distribution becomes sharp, and the generation of coarse particles as in the dry method is extremely rare.

Furthermore, the resin-coated nigrosine dye (D) can be obtained by heating and kneading the resin (C), which is a solid at room temperature, and the finely divided nigrosine dye slurry (B) by a flashing method and removing the solvent.
At this time, the content of the nigrosine dye contained in the refined nigrosine dye slurry (B) is preferably 5 to 50%. If it is less than 5%, the efficiency of solvent removal is poor, and if it is more than 50%, it becomes difficult to uniformly disperse in the resin during flushing.
The resin-coated nigrosine dye (D) in the present invention can be obtained as follows as an example. The finely divided nigrosine dye slurry (B) is transferred to a mixing and dispersing machine such as a kneader or a super mixer, and a room temperature solid resin (C) and other various additives as necessary are mixed and stirred. At this time, you may heat as needed. After the finely divided nigrosine dye component has been transferred to the resin, the separated solvent is removed by decantation, and the remaining kneaded product is removed using two or three rolls as necessary, and the resin-coated nigrosine dye (D) may be obtained.
Moreover, residual aniline in the nigrosine dye can be reduced by using the flushing method. The aniline content in the resin-coated nigrosine dye (D) is preferably suppressed to 500 ppm or less from the standpoint of obtaining charging aging stability. More preferably, it is 300 ppm or less.

  Resin that can be used at room temperature solid resin (C), that is, a resin that can be used for flushing is rosin-modified maleic acid resin, xylene resin, phenol resin, rosin-modified phenol resin, epoxy resin, ionomer resin, polyurethane resin, Examples include silicone resin, styrene-acrylic copolymer, polystyrene resin, polyester resin, polyethylene resin, polypropylene resin, styrene-butadiene copolymer, styrene-vinyl acetate copolymer, rosin ester, and rosin. Of these, rosin-modified maleic acid resin, xylene resin, styrene-acrylic copolymer, and polyester resin are preferably used. It is also preferable to use a resin having the same composition as the binder resin described later.

 In addition, the resin-coated nigrosine dye (D) is finer than the untreated nigrosine dye and reduced in aniline, so that not only good chargeability, fast rise of charge, and stability can be obtained, It has a glossy and glossy black color and has the effect of acting as a coloring aid such as assisting the coloring agent in the toner. This is considered to be due to the increase in blackness due to the increase in the specific surface area of the nigrosine dye by wet grinding, which also contributes to the improvement of the image quality of the black toner. This is also a preferable feature of the dry toner for development.

  The content of the nigrosine dye contained in the resin-coated nigrosine dye (D) is preferably in the range of 10 to 80% by weight. More preferably, it is in the range of 30 to 70% by weight. When the amount is less than 10% by weight, it is difficult to obtain the effect as a charge control agent. When the amount exceeds 80% by weight, not only is it difficult to disperse in the resin, but it is also difficult to remove the solvent at the time of flushing. It becomes difficult to remove aniline which is a residue in nigrosine.

  The amount of resin-coated nigrosine dye (D) used in the toner is uniquely determined by the performance of the target toner and the content of nigrosine in the resin-coated nigrosine dye (D). However, it is used in an amount of 0.3 to 10 parts by weight with respect to 100 parts by weight of the binder resin, and 0.5 to 5 parts by weight is preferable for maintaining excellent positive chargeability.

In the dry toner for developing an electrostatic charge image of the present invention, a charge control agent other than the nigrosine dye can be used as long as the object of the present invention is not impaired.
The positively chargeable charge control agent other than the nigrosine dye is not particularly limited, and a quaternary ammonium salt compound (for example, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutyl, which is known and commonly used for toners). Benzylammonium tetrafluoroborate), diorganotin oxide (eg dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide), diorganotin borate (dibutyltin borate, dioctyltin borate, dicyclohexyltin borate), onium compounds, triphenylmethane Compounds, fatty acid metal derivatives and the like can be used. A basic group-containing compound such as an amino group, an imino group, or an N-heterocycle, for example, a tertiary amino group-containing styrene acrylic resin can also be used in combination with the nigrosine dye as a positively chargeable charge control agent.
Depending on the application, a small amount of a negatively chargeable charge control agent such as an azo dye metal complex or a salicylic acid derivative metal complex salt can be used in combination. Negatively chargeable charge control agents include trimethylethane dyes, metal complexes of salicylic acid, metal complexes of benzylic acid, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex azo dyes, azochrome complexes, and other heavy metal-containing acids. Examples thereof include dyes, calixarene-type phenol condensates, cyclic polysaccharides, resins containing carboxyl groups and / or sulfonyl groups, and the like.

Any binder resin can be used as the binder resin used in the dry toner for developing an electrostatic charge image according to the present invention as long as it is known as a binder resin for a conventional dry toner for developing an electrostatic charge image. Examples of binder resins that can be used include homopolymers of styrene and its derivatives such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, and the like. Styrene-styrene derivative copolymer such as polymer; styrene-vinyl naphthalene copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-α-chloromethyl methacrylate copolymer, Styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene- Acrylonitrile-indene copolymer, etc. Styrene copolymer; polyvinyl chloride, phenol resin, natural modified phenol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy Examples thereof include resins, polyvinyl butyral, terpene resins, coumarone indene resins, and petroleum resins.
Among these, styrene homopolymers, styrene-styrene derivative copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, and polyester resins are particularly preferable.

  As a comonomer for a styrene monomer of a styrene-acrylic acid copolymer or a styrene-methacrylic acid copolymer, for example, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, Examples include 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, and the like.

  A crosslinked styrene copolymer is also a binder resin that can be preferably used. Examples of the comonomer used together with styrene to produce a crosslinked styrene-based copolymer include the styrene derivatives, acrylic acid, methacrylic acid, acrylic acid ester or methacrylic acid ester, acrylonitrile, methacrylonitrile, acrylamide, etc. A monocarboxylic acid having a double bond or a substituted product thereof; for example, a dicarboxylic acid having a double bond such as maleic acid, methyl maleate, butyl maleate, dimethyl maleate and the substituted product thereof; for example, vinyl chloride, vinyl acetate, Vinyl esters such as vinyl benzoate; ethylene-based olefins such as ethylene, propylene and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; for example vinyl methyl ether and vinyl ethyl ether , Vinyl ethers such as vinyl isobutyl ether; vinyl monomers are used alone or two or more kinds.

  As the crosslinking agent, compounds having two or more polymerizable double bonds are mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1, Carboxylic acid esters having two double bonds such as 3-butanediol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone; and three or more A compound having a vinyl group is used alone or as a mixture. These crosslinking agents are used in an amount of about 0.01 to 5 parts by weight, more preferably about 0.03 to 3 parts by weight with respect to 100 parts by weight of other monomer components.

The binder resin is a styrene having at least one peak in a region of 3 × 10 ^{3 to} 5 × 10 ⁴ in a molecular weight distribution measured by GPC, and having at least one peak or shoulder in a region of 10 ⁵ or more. A copolymer is preferred from the viewpoint of fixability. The binder resin having such a molecular weight distribution can be produced by mixing two or more kinds of resins having different average molecular weights, and can also be produced by using the crosslinking agent as a crosslinked resin. .

The molecular weight distribution by GPC is measured, for example, under the following conditions.
The column is stabilized in a 40 ° C. heat chamber, and tetrahydrofuran (THF) as a solvent is allowed to flow through the column at this temperature at a flow rate of 1 ml / min, and about 100 μl of a sample solution dissolved in THF is injected for measurement. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts.

As a standard polystyrene sample for preparing a calibration curve, for example, a standard polystyrene sample having a molecular weight of about 10 ² to 10 ⁷ manufactured by Tosoh Corporation or Showa Denko is used, and it is appropriate to use at least about 10 standard polystyrene samples. . An RI (refractive index) detector is used as the detector. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, combinations of shodex GPC KF-801, 802, 803, 804, 805, 806, 807, 800P manufactured by Showa Denko KK, TSKgel G1000H (HXL), G2000H (HXL), G3000H (HXL) manufactured by Tosoh Corporation, G4000H (HXL), G5000H (HXL), G6000H (HXL), G7000H (HXL), TSKguar
A combination of dcolumns can be given.

 The measurement sample is prepared as follows. That is, after putting a sample in THF and leaving it to stand for several hours, the sample is sufficiently shaken, mixed well with THF until the sample is no longer united, and further allowed to stand for 12 hours or more. At this time, the standing time in THF is set to be 24 hours or longer. Then, GPC measurement was performed on a sample processing filter (pore size 0.45 to 0.5 μm, for example, Mysori Disc H-25-5 manufactured by Tosoh Corp., Excro Disc 25CR manufactured by Gelman Science Japan Ltd., etc.). Sample for use. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.

  In the production of the vinyl polymer, a polymerization initiator is used. Any conventionally known polymerization initiator can be used as the polymerization initiator. Examples of the polymerization initiator include benzoyl peroxide, lauroyl peroxide, tertiary butyl hydroperoxide, tertiary butyl peroxybenzoate, ditertiary butyl peroxide, cumene hydroperoxide, dicumyl peroxide, azoisobutyro Nitrile, azobisvaleronitrile and the like are usually preferably used. The use ratio of the initiator to the vinyl monomer is generally 0.2 to 5% by weight. The polymerization temperature is appropriately selected according to the type of monomer and initiator used.

  A polyester resin is also preferably used as a binder resin for the dry toner for developing an electrostatic image of the present invention. Examples of the alcohol component constituting the polyester resin include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, , 6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenyl A, diols such as bisphenol derivatives, and polyhydric alcohols such as glycerin, sorbit and sorbitan.

  As the acid component, divalent carboxylic acids such as benzene dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and phthalic anhydride or anhydrides thereof; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid or Further, succinic acid substituted with an alkyl group having 16 to 18 carbon atoms or an anhydride thereof; unsaturated dicarboxylic acid such as fumaric acid, maleic acid, citraconic acid, itaconic acid, or an anhydride thereof. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid and anhydrides thereof.

  The preferred alcohol component is a bisphenol derivative, and the preferred acid component is phthalic acid, terephthalic acid, isophthalic acid or its anhydride, succinic acid, n-dodecenyl succinic acid or its anhydride, fumaric acid, maleic acid, maleic anhydride, etc. Tricarboxylic acids such as dicarboxylic acids, trimellitic acid or anhydrides thereof.

  Further, when using the pressure fixing method, a binder resin for pressure fixing toner can be used, for example, polyethylene, polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer. Examples thereof include polymers, ionomer resins, styrene-butadiene copolymers, styrene-isoprene copolymers, linear saturated polyesters, and paraffins.

In the dry toner for developing an electrostatic charge image of the present invention, it is preferable to use a colorant. In black toner, it is possible to obtain a black toner by containing a finely divided nigrosine dye, but by using a colorant such as carbon black, a good dry toner for developing an electrostatic image can be obtained. Can do. Carbon black plays a role of adjusting not only the colorant but also the resistance in the toner. By using carbon black, the quality of the image can be improved. That is, obtaining a higher density image, reducing fog on the image, preventing toner from being scattered in the machine, and the like.
As carbon black, either furnace black or channel black can be used. However, when furnace black carbon is used together with a finer nigrosine dye, the dispersibility is preferable and the result of less fogging of the image is obtained. Yes.
A more preferable image can be obtained by using a specific surface area of 30 to 300 m ² / g by the BET method. In particular, when used together with the resin-coated nigrosine dye (D), it is possible to obtain a toner having a good quality with a high image density and no problem of fogging and scattering inside the apparatus.
When carbon black having a specific surface area of more than 300 m ² / g by the BET method is used, it becomes difficult to disperse and distribute in the binder resin, fog increases, and toner scattering increases. There is a tendency to deteriorate the quality of the copied image. In particular, fogging occurs remarkably in a high-temperature and high-humidity environment, and toner scattering in the machine may occur. If a specific surface area of less than 30 m ² / g is used, it may be difficult for the colorant particles to sufficiently color the toner particles, and a desired image density as a toner may not be obtained.

Further, when the dry toner for developing an electrostatic charge image of the present invention is used as a magnetic toner, a magnetic powder is internally added. As the magnetic powder internally added to these toners, any powders of alloys, oxides, compounds and the like containing ferromagnetic elements that are conventionally used in the production of magnetic toners can be used.
Examples of these magnetic powders include magnetic iron oxides such as magnetite, maghemite, and ferrite, or compounds of divalent metals and iron oxides, metals such as iron, cobalt, and nickel, or aluminums of these metals, cobalt, copper, Examples include powders of alloys of metals such as lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, and mixtures of these powders. These magnetic powders preferably have an average particle diameter of 0.05 to 2.0 μm, more preferably about 0.1 to 0.5 μm. The content of the magnetic powder in the toner is about 5 to 200 parts by weight, preferably 10 to 150 parts by weight, with respect to 100 parts by weight of the thermoplastic resin. Further, the saturation magnetization of the toner is preferably 15 to 35 emu / g (measuring magnetic field: 1 kilo-Oersted).
In the dry toner for developing an electrostatic charge image of the present invention, the magnetic powder also functions as a colorant. When the magnetic powder is used, other colorants may not be used. If necessary, for example, the aforementioned carbon black, copper phthalocyanine, iron black, etc. may be used together.

In the dry toner for developing an electrostatic charge image of the present invention, a release agent can be used. The release agent is selected from the group consisting of hydrocarbon waxes such as polypropylene wax, polyethylene wax and Fiescher-Tropsch wax, and natural ester waxes such as synthetic ester waxes, carnauba wax and rice wax. A mold is used.
It is difficult to disperse and distribute the above release agent uniformly and preferably in the binder resin. For this reason, when these release agents are used, it is preferable to produce the toner after performing the following treatment.
(1) A release agent is mixed in advance during the production of the binder resin to obtain a release agent-containing binder resin.
(2) The release agent is pulverized to 10 μm or less and then mixed with a binder resin or the like to produce a toner.

  In the dry toner for developing an electrostatic image of the present invention, known additives used in the production of the toner, such as a lubricant, a fluidizing agent, an abrasive, a conductivity imparting agent, and an image peeling preventing agent, as necessary. Can be added internally or externally. Examples of these additives include polyvinylidene fluoride and zinc stearate as a lubricant, and silica, aluminum oxide, titanium oxide, silicon aluminum co-oxide produced by a dry method or a wet method as a fluidity improver. , Silicon-titanium co-oxide and those hydrophobized, etc., and abrasives include silicon nitride, cerium oxide, silicon carbide, strontium titanate, tungsten carbide, calcium carbonate, and those hydrophobized. Examples of the conductivity imparting agent include carbon black and tin oxide. In addition, fine powders of fluorine-containing polymers such as polyvinylidene fluoride are preferable from the viewpoints of fluidity, abrasiveness, charge stability, and the like.

  In the dry toner for developing an electrostatic charge image of the present invention, it is preferable to contain hydrophobized silica, silicon aluminum co-oxide, and silicon titanium co-oxide fine powder as external additives. Examples of the hydrophobic treatment of these fine powders include treatment with a silane coupling agent such as silicon oil, tetramethyldisilazane, dimethyldichlorosilane, and dimethyldimethoxysilane. The amount of the hydrophobized fine powder such as silica subjected to hydrophobization treatment is 0.01 to 20%, preferably 0.03 to 5%, based on the developer weight.

  The particle diameter of the dry toner for developing an electrostatic charge image of the present invention is 1 to 30 μm, preferably 3 to 15 μm in volume average particle diameter. Since the resin-coated nigrosine dye (D) contains finer particles than the conventionally used nigrosine dye, it is possible to obtain very preferable dispersibility, distribution, and blendability even in a small particle size toner. Is. The toner particle size distribution can be measured using, for example, a Coulter counter (multisizer).

The dry toner for developing an electrostatic charge image of the present invention can be produced using a conventionally known toner production method. In general, the above-described toner constituent materials are sufficiently mixed by a mixer such as a ball mill or a Henschel mixer, and then kneaded thoroughly using a thermal kneader such as a hot roll kneader, a uniaxial or biaxial extruder. After cooling and solidifying, a method of coarsely pulverizing mechanically using a pulverizer such as a hammer mill, then finely pulverizing with a jet mill or the like and then classifying is preferable. However, the method for producing the toner is not limited to this method, and the method for producing the toner by the so-called microcapsule method, the method of dispersing the toner after dispersing other toner constituent materials in the binder resin solution, and the binder, Other methods such as a polymerization toner manufacturing method in which a predetermined material is mixed with a monomer forming a resin, and emulsion or suspension polymerization is performed to obtain a toner can be arbitrarily employed.
Further, if necessary, the classified toner and the external additive are sufficiently mixed using a mixer such as a Henschel mixer, and the dry toner for electrostatic charge development of the present invention can be produced through a sieving step.

  The dry toner for developing an electrostatic image of the present invention can be mixed with a carrier and used as a two-component developer. The carrier that can be used together with the dry toner of the present invention may be any conventionally known carrier. Examples of the carrier that can be used include magnetic powders such as iron powder, ferrite powder, and nickel powder, and those whose surfaces are treated with a resin or the like. Examples of the resin covering the carrier surface include styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, acrylic acid ester copolymer, methacrylic acid ester copolymer, fluorine-containing resin, silicone-containing resin, and polyamide. Examples thereof include a resin, an ionomer resin, a polyphenylene sulfide resin, and a mixture thereof. Among these, fluorine-containing resins and silicone-containing resins are particularly preferable because they hardly form spent toner. Moreover, it is preferable that the weight average particle diameter of a carrier is the range of 30-100 micrometers.

Charge Control Agent Production Example [Nigrosine Dye (A) Nigrosine Base Production Example]
Crude nigrosine was obtained by oxidizing and reacting aniline and aniline hydrochloride with nitrobenzene at 160 to 180 ° C. in the presence of iron chloride, iron and hydrochloric acid. Furthermore, after neutralizing the crude nigrosine, aniline and sodium hydroxide solution were added to make a base treatment, and then the precipitates of nigrosine and iron hydroxide were separated by screw decanter centrifugation and the iron hydroxide precipitate was removed. The obtained liquid was washed with water. After washing with water, in order to remove the remaining nitrobenzene and aniline, methanol was further added, stirred and washed while heating to 60 ° C., filtered and dried, and pulverized to a volume average particle size of 7 μm with a jet mill. And nigrosine base A was obtained. The content of aniline at this time was 2500 ppm.

[Resin-coated nigrosine dye production example 1]
The above-obtained nigrosine base A (aniline amount 2500 ppm) 800 g and methanol 2000 g were weighed in a beaker, sufficiently stirred and mixed, and nigrosine base A was dispersed in the methanol solution. (Slurry concentration is 28.5 wt.%) Circulating the slurry in which this nigrosine base A is dispersed using a wet pulverizer as a medium agitating mill, Dino Mill Multilab (manufactured by Shinmaru Enterprises, capacity 1.4 L) The operation was performed for 15 minutes and wet pulverization was performed.
The wet pulverization conditions at this time were as follows.
Agitator disk (material: zirconia) peripheral speed 10m / s, cylinder ZTA,
Media (Material: Zirconia) Diameter 1.25mm, Filling rate 70%
Solution flow rate 45 kg / h, cooling water 5 l / min. , Pressure 0.1Kg / cm ²
After wet pulverization for 15 minutes, a finely divided nigrosine dye slurry 1 was obtained. When the particle size distribution was confirmed, D50 (cumulative 50 percent diameter) was 1.28 μm.
Next, the process proceeds to a flushing process.
100 parts by weight of finely divided nigrosine dye slurry 1 (nigrosine concentration 28.5 wt.%)
30 parts by weight of rosin-modified maleic resin The above raw materials were charged into a stainless steel 1 gallon kneader (manufactured by Inoue Seisakusho) and mixed while heating to 100 ° C., and the nigrosine dye transferred to the resin (flushing) in about 10 minutes. After removing the separated methanol from the kneader, resin-coated nigrosine dye 1 (nigrosine content 48.7%) was obtained. The content of aniline at this time was 150 ppm.

[Production example 2 of resin-coated nigrosine dye]
The above-obtained nigrosine base A (aniline amount 2500 ppm) 800 g and methanol 2000 g were weighed in a beaker, sufficiently stirred and mixed, and nigrosine base A was dispersed in the methanol solution. (Slurry concentration is 28.5 wt.%) Circulating the slurry in which this nigrosine base A is dispersed using a wet pulverizer as a medium agitating mill, Dino Mill Multilab (manufactured by Shinmaru Enterprises, capacity 1.4 L) The operation was performed for 8 minutes and wet pulverization was performed.
The wet pulverization conditions at this time were as follows.
Agitator disk (material: zirconia) peripheral speed 10m / s, cylinder ZTA,
Media (Material: Zirconia) Diameter 1.25mm, Filling rate 70%
Solution flow rate 45 kg / h, cooling water 5 l / min. , Pressure 0.1Kg / cm ²
After performing wet pulverization for 8 minutes, slurry 2 of the refined nigrosine dye was obtained. When the particle size distribution was confirmed, D50 (cumulative 50 percent diameter) was 1.75 μm.
Next, the process proceeds to a flushing process.
100 parts by weight of finely divided nigrosine dye slurry 2 (nigrosine concentration 28.5 wt.%)
30 parts by weight of rosin-modified maleic resin The above raw materials were charged into a stainless steel 1 gallon kneader (manufactured by Inoue Seisakusho) and mixed while heating to 100 ° C., and the nigrosine dye transferred to the resin (flushing) in about 10 minutes. After removing the separated methanol from the kneader, a resin-coated nigrosine dye 2 (nigrosine content 48.7%) was obtained. The content of aniline at this time was 100 ppm.

[Production Example 3 of Resin-Coated Nigrosine Dye]
The above-obtained nigrosine base A (aniline amount 2500 ppm) 800 g and methanol 2000 g were weighed in a beaker, sufficiently stirred and mixed, and nigrosine base A was dispersed in the methanol solution. (Slurry concentration is 28.5 wt.%) Circulating the slurry in which this nigrosine base A is dispersed using a wet pulverizer as a medium agitating mill, Dino Mill Multilab (manufactured by Shinmaru Enterprises, capacity 1.4 L) The operation was performed for 15 minutes and wet pulverization was performed.
The wet pulverization conditions at this time were as follows.
Agitator disk (material: zirconia) peripheral speed 10m / s, cylinder ZTA,
Media (Material: Zirconia) Diameter 0.5mm, Filling rate 70%
Solution flow rate 45 kg / h, cooling water 5 l / min. , Pressure 0.1Kg / cm ²
After wet pulverization for 15 minutes, a finely divided nigrosine dye slurry 3 was obtained. When the particle size distribution was confirmed, D50 (cumulative 50 percent diameter) was 0.30 μm.
Next, the process proceeds to a flushing process.
100 parts by weight of finely divided nigrosine dye slurry 3 (nigrosine concentration 28.5 wt.%)
30 parts by weight of rosin-modified maleic resin The above raw materials were charged into a stainless steel 1 gallon kneader (manufactured by Inoue Seisakusho) and mixed while heating to 100 ° C., and the nigrosine dye transferred to the resin (flushing) in about 10 minutes. After removing the separated methanol from the kneader, a resin-coated nigrosine dye 3 (nigrosine content 48.7%) was obtained. The aniline content at this time was 250 ppm.

[Production Example 4 of Resin-Coated Nigrosine Dye]
800 g of commercially available nigrosine-based CHUO CCA-1 (manufactured by Chuo Gosei Chemical Co., Ltd., aniline amount 2000 ppm) and 2000 g of methanol were weighed in a beaker, sufficiently stirred and mixed, and nigrosine-based CCA-1 was dispersed in the methanol solution. (Slurry concentration is 28.5 wt.%) The slurry in which this nigrosine base CCA-1 is dispersed is used as a medium agitation mill, a wet pulverizer, Dino Mill Multilab (Shinmaru Enterprises Co., Ltd., capacity 1.4 L). Then, the circulation operation was performed for 15 minutes, and wet pulverization was performed.
The wet pulverization conditions at this time were as follows.
Agitator disk (material: zirconia) peripheral speed 10m / s, cylinder ZTA,
Media (Material: Zirconia) Diameter 1.25mm, Filling rate 70%
Solution flow rate 45 kg / h, cooling water 5 l / min. , Pressure 0.1Kg / cm ²
After wet pulverization for 15 minutes, a finely divided nigrosine dye slurry 4 was obtained. When the particle size distribution was confirmed, D50 (cumulative 50 percent diameter) was 1.35 μm.
Next, the process proceeds to a flushing process.
Slurry 4 of refined nigrosine dye 4 100 parts by weight (concentration of nigrosine 28.5 wt.%)
30 parts by weight of styrene-butyl acrylate copolymer The above raw materials were charged into a stainless steel 1 gallon kneader (manufactured by Inoue Seisakusho) and mixed while heating to 100 ° C. The nigrosine dye transferred to the resin in about 10 minutes (flushing) did. After removing the separated methanol from the kneader, a resin-coated nigrosine dye 4 (nigrosine content 48.7%) was obtained. The content of aniline at this time was 100 ppm.

[Resin-coated nigrosine dye production example 5]
The above-obtained nigrosine base A (aniline amount 2500 ppm) 800 g and methanol 2000 g were weighed in a beaker, sufficiently stirred and mixed, and nigrosine base A was dispersed in the methanol solution. (Slurry concentration is 28.5 wt.%) Circulating the slurry in which this nigrosine base A is dispersed using a wet pulverizer as a medium agitating mill, Dino Mill Multilab (manufactured by Shinmaru Enterprises, capacity 1.4 L) The operation was performed for 30 minutes, and wet pulverization was performed.
The wet pulverization conditions at this time were as follows.
Agitator disk (material: zirconia) peripheral speed 10m / s, cylinder ZTA,
Media (Material: Zirconia) Diameter 0.5mm, Filling rate 70%
Solution flow rate 45 kg / h, cooling water 5 l / min. , Pressure 0.1Kg / cm ²
After wet pulverization for 30 minutes, a slurry 5 of refined nigrosine dye was obtained. When the particle size distribution was confirmed, D50 (cumulative 50 percent diameter) was 0.15 μm.
Next, the process proceeds to a flushing process.
Slurry 5 of finely divided nigrosine dye 5 100 parts by weight (nigrosine concentration 28.5 wt.%)
30 parts by weight of rosin-modified maleic resin The above raw materials were charged into a stainless steel 1 gallon kneader (manufactured by Inoue Seisakusho) and mixed while heating to 100 ° C., and the nigrosine dye transferred to the resin (flushing) in about 10 minutes. After removing the separated methanol from the kneader, a resin-coated nigrosine dye 5 (nigrosine content 48.7%) was obtained. At this time, the aniline content was 350 ppm.

[Resin-coated nigrosine dye production example 6]
The above-obtained nigrosine base A (aniline amount 2500 ppm) 800 g and methanol 2000 g were weighed in a beaker, sufficiently stirred and mixed, and nigrosine base A was dispersed in the methanol solution. (Slurry concentration is 28.5 wt.%) Circulating the slurry in which this nigrosine base A is dispersed using a wet pulverizer as a medium agitating mill, Dino Mill Multilab (manufactured by Shinmaru Enterprises, capacity 1.4 L) The operation was performed for 8 minutes and wet pulverization was performed.
The wet pulverization conditions at this time were as follows.
Agitator disk (material: zirconia) peripheral speed 10m / s, cylinder ZTA,
Media (Material: Zirconia) Diameter 1.5mm, Filling rate 60%
Solution flow rate 45 kg / h, cooling water 5 l / min. , Pressure 0.1Kg / cm ²
After performing wet pulverization for 8 minutes, slurry 6 of the refined nigrosine dye was obtained. When the particle size distribution was confirmed, D50 (cumulative 50 percent diameter) was 2.50 μm.
Next, the process proceeds to a flushing process.
Slurry 6 of refined nigrosine dye 6 100 parts by weight (concentration of nigrosine 28.5 wt.%)
30 parts by weight of rosin-modified maleic resin The above raw materials were charged into a stainless steel 1 gallon kneader (manufactured by Inoue Seisakusho) and mixed while heating to 100 ° C., and the nigrosine dye transferred to the resin (flushing) in about 10 minutes. After removing the separated methanol from the kneader, a resin-coated nigrosine dye 6 (nigrosine content 48.7%) was obtained. At this time, the aniline content was 110 ppm.

The particle size distribution of the refined nigrosine dye slurry (B) was measured using a Microtrac particle size analyzer UPA150 (manufactured by Nikkiso Co., Ltd.). The measurement conditions at this time were as follows.
Transparent Particles: Yes
Spherical Particles: Yes
Part Reflective Index: 1.50
Part. Density: 1.00 g / cm3
Fluid: Methanol
Fluid Refractive Index: 1.33
Measurement time: 180s
As for the average particle diameter, D50 and a cumulative 50 percent diameter (volume distribution) were used as indicators of the average particle diameter.

 The analysis of the aniline content contained in the resin-coated nigrosine dye (D) was performed using Gas Chromatograph Agilent (Hewlett Packard) Model 6890. The conditions at that time were column HP-INNOWAX, temperature 50 to 240 ° C. (15 ° C./min), the sample was dissolved in ethanol, the volume was adjusted to 10 ml, and the sample solution was directly injected into the GC. As a reference sample, a standard solution of aniline 10 ppm was prepared, and the aniline content was quantified.

Styrene-n-butyl acrylate copolymer 56 parts by weight Magnetic iron oxide 40 parts by weight Resin-coated nigrosine dye 1 2 parts by weight Low molecular weight polypropylene wax (average particle size 8 μm) 2 parts by weight were premixed with a Henschel mixer and then biaxial Melting and kneading were performed with a heating kneader to obtain chips after cooling, and the chips were roughly crushed to 1 mm or less with a sample mill to obtain chips. Subsequently, the mixture was finely pulverized and classified by a jet mill pulverizer to obtain toner mother particles having a volume average particle diameter of 10.5 μm. To 100 parts by weight of the toner base particles, 0.3 parts by weight of hydrophobic silica (Aerosil R972) and 0.5 parts by weight of tungsten carbide (WC-10 manufactured by Nippon Shin Metal Co., Ltd.) are added and mixed with a Henschel mixer. A positively chargeable magnetic toner was obtained through a sieving step.
Further, using this positively chargeable magnetic toner, a live-action test was performed using a commercially available analog copying machine (NP-2120 manufactured by Canon Inc.), and image density (initial and values after 50000 sheets), fog (initial and 50000 sheets). Later values), evaluation of in-flight scattering gave good results. Further, when the image was confirmed after being left for 14 days in the state after 50000 sheets, the image density was not lowered due to charge decay, and the fog was not increased. The results are shown in Table 1.

  Here, the image density was measured using a Macbeth photometer. The concentration may be 1.35 or more. The fog was measured by measuring the reflectance with a photovolt. 1.5% or less is a good value. Further, the scattering of the toner in the machine was performed by checking whether or not the scattered toner was present on the transfer charger of the copying machine. When toner scattering is observed on the transfer charger, image contamination is caused.

[Examples 2-4, Comparative Examples 1-2]
A positively chargeable magnetic toner was obtained and evaluated in the same manner as in Example 1 except that the resin-coated nigrosine dyes 2 to 6 listed in Table 1 were used. The results are shown in Table 1.

[Example 5]
Styrene-n-butyl acrylate copolymer 89 parts by weight Carbon black (furnace carbon, specific surface area 45 m ² / g) 7 parts by weight Resin-coated nigrosine dye 1 2 parts by weight Low molecular weight polypropylene wax (average particle size 8 μm) 2 parts by weight After premixing with a Henschel mixer, melt kneading was performed with a biaxial heating kneader to obtain chips after cooling, and crushing to 1 mm or less with a sample mill to obtain chips. Subsequently, after finely pulverizing and classifying with a jet mill, a toner base particle having a volume average particle diameter of 10.0 μm was obtained. To 100 parts by weight of the toner base particles, 0.3 parts by weight of hydrophobic silica (Aerosil RA200HS) and 0.5 parts by weight of tungsten carbide (WC-10 manufactured by Nippon Shin Metal Co., Ltd.) are added and mixed with a Henschel mixer. Through a sieving step, a positively chargeable nonmagnetic toner was obtained.
Furthermore, using a Cu-Zn ferrite carrier (DFC-100 made by Dowa Iron Powder Co., Ltd.) coated with a straight silicone resin (Toray Dow Corning SR2411), a developer was prepared at a toner concentration of 4.5%, and a commercially available analog copy was made. A real image test using an image test of the developer and the positively chargeable non-magnetic toner using a machine (SF-2030 manufactured by Sharp Corporation), and image density (initial and values after 80000 sheets), fog (initial and The value after 80,000 sheets) was evaluated when the in-flight scattering was evaluated. Further, after confirming the image after leaving for 80000 sheets for 14 days, an increase in fog due to charge decay, scattering in the machine, etc. were not found, and the result was good. The results at this time are shown in Table 2.

[Examples 6-8, Comparative Examples 3-4]
A positively chargeable nonmagnetic toner was obtained and evaluated in the same manner as in Example 5 except that the charge control agents 2 to 6 shown in Table 2 were used. The results are shown in Table 2.

The dry toner for developing an electrostatic charge image of the present invention can be preferably used in an electrophotographic dry developer, a copying machine using the toner, a printer, and the like. Further, since the nigrosine dye in the toner is miniaturized, a small amount is preferable. Since the charge control can be performed and the content of the remaining aniline is reduced, the toner is preferably used as an environmental countermeasure toner.

Claims (6)

  Nigrosine dye (A) is wet pulverized to obtain a nigrosine dye slurry (B) that has been refined to have a volume average particle diameter of 0.2 to 2.0 μm, and then the slurry (B) and solid at room temperature are obtained. An electrostatic charge image development obtained by heating and kneading a resin-coated nigrosine dye (D), a colorant, and a binder resin obtained by kneading the resin (C) with heat and then removing the solvent Dry toner.   2. The dry toner for developing electrostatic images according to claim 1, wherein the aniline content in the resin-coated nigrosine dye (D) is 500 ppm or less.   3. The dry toner for developing an electrostatic charge image according to claim 1, wherein the solvent for wet pulverization is a lower alcohol having 3 or less carbon atoms.   The dry toner for developing an electrostatic charge image according to any one of claims 1 to 3, wherein the wet pulverizing apparatus is a medium stirring mill.   The dry toner for developing an electrostatic charge image according to any one of claims 1 to 4, wherein the nigrosine dye (A) is based on nigrosine. Nigrosine dye (A) is wet pulverized to obtain a nigrosine dye slurry (B) that has been refined to have a volume average particle diameter of 0.2 to 2.0 μm, and then the slurry (B) and solid at room temperature are obtained. An electrostatic charge image development obtained by heating and kneading a resin-coated nigrosine dye (D), a colorant, and a binder resin obtained by kneading the resin (C) with heat and then removing the solvent For producing a dry toner.