JP2007114292A - External additive for toner, electrophotographic toner, and electrophotographic developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an external additive for a toner capable of suppressing the occurrence of toner filming without shortening the lifetime of a photoreceptor. <P>SOLUTION: The external additive for the toner is composed of two or more layers including a surface layer and is characterized in that the Vickers hardness of the surface layer is ≥15 GPa and the Vickers hardness of any one layer provided on the side inner than the surface layer is ≤10 GPa. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an external additive for toner that is externally added to the surface of toner particles used for developing an electrostatic charge image in an electrophotographic apparatus utilizing an electrophotographic process such as a copying machine, a printer, and a facsimile machine, and The present invention relates to an electrophotographic toner and an electrophotographic developer using the same.

In electrophotography, an electrostatic latent image is generally formed by charging and exposure processes, and then the latent image is developed using a developer containing toner, and transferred to a transfer material such as paper as necessary. Thereafter, the material is fixed by heating, pressure, heat and pressure, or solvent vapor to obtain a copy.
The dry developer used in such an electrophotographic method is required to have excellent chargeability, fluidity, fixability, cleanability and the like in order to have process compatibility. In order to enhance these characteristics, it is often performed to externally add inorganic fine powder that has been hydrophobized to toner particles. As the fine inorganic powder, for example, silica-based fine particles are used.
However, silica-based fine particles have a strong negative chargeability and excessively increase the charge amount of the negatively chargeable toner under low temperature and low humidity, while taking in moisture under high temperature and high humidity greatly reduces the charge amount. Therefore, there is a problem that a large difference is generated between the charge amounts of the two, which may cause blurring and background fogging.

  Many methods for externally adding inorganic oxides such as titania, alumina, and zinc oxide have been proposed to solve the problems of such silica-based materials. Since these inorganic oxides have less moisture uptake than silica, the environmental dependency of charging can be reduced. However, since the negative chargeability is very weak compared with silica, a sufficient charge level could not be obtained. Therefore, a method of externally adding fine particles obtained by combining these inorganic oxides has been proposed.

For example, a toner has been proposed in which fine particles having a core-shell structure in which inorganic fine particles having excellent environmental stability such as titania, alumina, and zinc oxide are coated with highly chargeable silica are externally added (see Patent Document 1). However, this technology has a silica layer on the outermost surface, so that under high temperature and high humidity, it is not possible to suppress the intake of moisture over time, and the charge amount of the toner decreases and fogging occurs. Occurs.
Contrary to this, a toner having a core-shell structure in which silica particles are coated with titania, aluminum, zinc oxide or the like is externally added to impart sufficient negative chargeability, and a toner excellent in environmental safety has been proposed. (See Patent Document 2). In this technology, silica having a strong negative chargeability is used for the core of the fine particles, so that an increase in the amount of charge with time under low temperature and low humidity cannot be suppressed, resulting in blurring.
As described above, the toner externally added with fine particles having a core-shell structure formed by combining two kinds of metal inorganic oxides has a sufficient negative chargeability at an initial stage and is excellent in environmental stability. However, over time, fogging under high temperature and high humidity and blurring under low temperature and low humidity cannot be suppressed.

On the other hand, a phenomenon (so-called toner filming) in which the toner remaining without being transferred accumulates on the photoreceptor over time is known. As a method for suppressing this phenomenon, alumina fine particles are used as toner particles. It has been proposed to add externally (see Patent Document 3).
However, since the alumina fine particles are very hard, the polishing effect is strong, and not only the toner adhered and accumulated on the photoreceptor is removed, but also the photoreceptor is scraped. For this reason, when toner with externally added alumina fine particles is used, it is possible to suppress the occurrence of toner filming that causes image color streak defects, but the surface of the photoreceptor is excessively polished, resulting in alumina There is a problem that the life of the photoreceptor is shortened as compared with the case of using toner without external addition of fine particles.
JP 2002-182424 A JP 2002-29730 A Publication 2000-250251

  An object of the present invention is to solve the above problems. That is, the present invention provides an external additive for toner that can suppress the occurrence of toner filming without shortening the life of the photoreceptor, and an electrophotographic toner and an electrophotographic developer using the same. The issue is to provide.

The above-mentioned subject is achieved by the following present invention. That is, the present invention
<1>
It consists of two or more layers including the surface layer,
The external additive for toner, wherein the surface layer has a Vickers hardness of 15 GPa or more, and at least one of the layers provided inside the surface layer has a Vickers hardness of 10 GPa or less.

<2>
The surface layer, a core layer provided inside the surface layer, and an intermediate layer provided between the core layer and the surface layer,
The core layer has a Vickers hardness of 15 GPa or less,
<2> The external additive for toner according to <1>, wherein the volume resistance of the intermediate layer is 10 ¹⁵ Ω · cm or more.

<3>
The external additive for toner according to <2>, wherein the core layer contains titania and / or zinc oxide, the intermediate layer contains silica, and the surface layer contains alumina.

<4>
<3> The external additive for toner according to <3>, wherein the shape is needle-shaped, and the core layer contains titania.

<5>
The external additive for toner according to <4>, wherein the minor axis is in the range of 20 to 30 nm and the major axis is in the range of 80 to 120 nm.

<6>
The surface layer, a core layer provided inside the surface layer, and an intermediate layer provided between the core layer and the surface layer,
The volume resistance of the core layer is 10 ¹⁵ Ω · cm or more,
The external additive for toner according to <1>, wherein the intermediate layer has a Vickers hardness of 10 GPa or less.

<7>
The external additive for toner according to <6>, wherein the core layer contains silica, the intermediate layer contains titania and / or zinc oxide, and the surface layer contains alumina.

<8>
The external additive for toner according to any one of <1> to <7>, wherein the surface has hydrophobicity.

<9>
The external additive for toner according to any one of <1> to <8>, wherein the surface is hydrophobized with alkoxysilane.

<10>
An electrophotographic toner comprising toner particles and the toner additive according to any one of <1> to <9> externally added to the surface of the toner particles.

<11>
<10> An electrophotographic developer comprising the electrophotographic toner according to <10>.

  As described above, according to the present invention, an external additive for toner capable of suppressing the occurrence of toner filming without shortening the life of the photoreceptor, and an electrophotographic toner and electrophotographic development using the same. Providing an agent can be provided.

(External additive for toner)
The external additive for toner of the present invention (hereinafter sometimes simply referred to as “external additive”) is composed of two or more layers including a surface layer, and the surface layer has a Vickers hardness of 15 GPa or more. The Vickers hardness of at least any one layer provided inside the layer is 10 GPa or less.

That is, the external additive for toner of the present invention has a surface layer having a hardness equal to or higher than that of alumina (Vickers hardness: 20 GPa), so that the toner adhered and deposited on the surface of the photoreceptor can be polished, and toner filming can be performed. Can be suppressed. On the other hand, since a softer layer having a lower hardness than the surface layer is provided inside the surface layer, this layer serves as a cushion to relieve the surface layer when excessive pressure is applied. Therefore, excessive wear on the surface of the photoreceptor can be suppressed.
Therefore, when image formation is performed using a toner externally added with the external additive for toner of the present invention, toner filming can be suppressed in the same manner as a conventional toner externally added with alumina fine particles. Unlike the alumina fine particles, since the excessive polishing effect is not exhibited, the life of the photosensitive member is not shortened.

  The surface layer needs to have a Vickers hardness of 15 GPa or more, more preferably 17 GPa or more, and further preferably 20 GPa or more. When the surface layer has a Vickers hardness of less than 15 GPa, toner filming cannot be suppressed. When the hardness of the surface layer is too high, the life of the photoreceptor may be shortened due to an excessive polishing effect. Therefore, the Vickers hardness of the surface layer is preferably 30 GPa or less, and more preferably 25 GPa or less.

  Further, at least any one layer provided on the inner side of the surface layer, that is, a layer having a function (cushion effect) for relaxing excessive pressure applied to the surface layer when the surface of the photoreceptor is polished (hereinafter referred to as “cushion”). The Vickers hardness of the layer may be 10 GPa or less, more preferably 8 GPa or less, and even more preferably 5 GPa or less. When the Vickers hardness of the cushion layer exceeds 10 GPa, the excessive pressure applied to the surface layer cannot be relieved when polishing the surface of the photoreceptor, and the surface of the photoreceptor is excessively worn to shorten the life of the photoreceptor. It will shrink.

  However, when the hardness of the cushion layer is too low, the cushioning effect becomes excessive, so that the polishing ability of the surface layer is diminished more than necessary, and it may be difficult to suppress the occurrence of toner filming. . Therefore, the hardness of the cushion layer is preferably 2 GPa or more, and more preferably 3 GPa or more.

The layer structure of the external additive for toner of the present invention is not particularly limited as long as it is composed of two or more layers including a surface layer. However, the layer is composed of a core layer and a surface layer covering the core layer. In the case of comprising, the core layer also serves as a cushion layer.
Moreover, when it consists of three or more layers, at least one layer except a surface layer should just have the function of a cushion layer. For example, in the case of a three-layer configuration including a surface layer, a core layer provided inside the surface layer, and an intermediate layer provided between the core layer and the surface layer, the core layer and / or the intermediate layer is a cushion. What is necessary is just to have the function of a layer.

  In addition, in order to balance the polishing effect by the surface layer and the cushion effect by the cushion layer, and not to wear the photoreceptor excessively, and to obtain a polishing ability sufficient to suppress toner filming, In addition to the hardness of the surface layer and cushion layer, the thickness is also important. From such a viewpoint, the ratio of the thickness of the surface layer to the cushion layer (surface layer thickness: cushion layer thickness) is preferably in the range of 1: 9 to 4: 6, and is in the range of 2: 8 to 3: 7. The inside is more preferable. If it is out of this range, the polishing ability becomes excessive and the life of the photoconductor may be shortened, or the polishing ability may be insufficient to prevent the occurrence of toner filming.

Here, examples of the material that can be used for the surface layer include alumina (Al ₂ O ₃ , Vickers hardness: 20 GPa), zirconia (Vickers hardness: 16 GPa), and it is particularly preferable to use alumina.
Examples of materials that can be used for the cushion layer include titania (TiO ₂ , Vickers hardness: 7 GPa), zinc oxide (Vickers hardness: 5 GPa), and titania is preferably used.
Furthermore, when the layer structure of the external additive for toner is 3 layers or more, examples of materials that can be used for other layers other than the surface layer and the cushion layer include silica (SiO ₂ ). It is preferable to use silica.

Moreover, since the external additive of the present invention has a layer structure of two or more layers like the conventional external additive having a core-shell structure, by selecting the material constituting the layer provided inside the surface layer, In addition to the function as an abrasive capable of achieving both a long life of the photoreceptor and suppression of toner filming, other functions can be easily achieved.
From this point of view, the configuration of the external additive of the present invention that is particularly preferable will be described in more detail by dividing it into a first aspect and a second aspect.

-External additive of the first aspect-
The external additive of the first aspect has a three-layer structure including a surface layer, a core layer provided inside the surface layer, and an intermediate layer provided between the core layer and the surface layer. The layer functions as a cushion layer, and the volume resistance of the intermediate layer is 10 ¹⁵ Ω · cm or more.
As a result, the external additive of the first aspect is capable of (1) extending both the life of the photoreceptor and suppressing toner filming, and (2) having sufficient negative chargeability. In addition, a charged state necessary for development can be imparted to the toner particles.

As the material constituting each layer of the external additive, it is particularly preferable that the core layer includes titania and / or zinc oxide, the intermediate layer includes silica, and the surface layer includes alumina.
In this case, a change in the amount of moisture adsorbed on the silica due to a change in temperature and humidity, which is a defect of silica excellent in negative chargeability, can be suppressed by the surface layer containing alumina in the intermediate layer containing silica. Therefore, it is possible to suppress the environmental dependency of the charge amount due to the change in the moisture adsorption amount of silica. Furthermore, although titania and zinc oxide used for the core layer have a weak negative chargeability, the environmental dependency of the charge amount is small, and therefore, silica can complement each other's characteristic defects.
Therefore, in addition to the effects shown in the items (1) and (2) above, (3) the environmental dependency of the charge amount can be further reduced.

Further, the shape of the external additive of the first aspect is not particularly limited, but it can be formed into a needle shape by selecting a material used for the core layer. In this case, it is preferable to use titania (TiO) which is a needle-like crystal as a material used for the core layer.
By making the shape of the external additive into a needle shape, the contact area between the photoconductor and the external additive is increased, the stress that the external additive is pressed against the photoconductor can be reduced, and the function of the cushion layer is supplemented. be able to. In addition, the fluidity of the external additive can be improved and the adhesive force can be reduced.
When the shape of the external additive of the first aspect is acicular, the minor axis is preferably in the range of 20 to 30 nm, and the major axis is preferably in the range of 80 to 150 nm, and in the range of 80 to 120 nm. More preferably.
In the present invention, the shape and size of the external additive are confirmed from an image obtained by a scanning electron microscope (manufactured by Hitachi, Ltd., S-4700), and the size (particle size, major axis, minor axis) is confirmed. Sampled 100 external additive particles, and calculated | required from the average value.

-External additive of second aspect-
The external additive of the second aspect has a three-layer structure comprising a surface layer, a core layer provided inside the surface layer, and an intermediate layer provided between the core layer and the surface layer. The volume resistance of the layer is 10 ¹⁵ Ω · cm or more, and the intermediate layer functions as a cushion layer.
As a result, the external additive of the second aspect, as well as the external additive of the first aspect, can achieve both (1) long life of the photoreceptor and suppression of toner filming. (2) Since the toner has a sufficient negative chargeability, a charged state necessary for development can be imparted to the toner particles.

As a material constituting each layer of the external additive, it is particularly preferable that the core layer contains silica, the intermediate layer contains titania and / or zinc oxide, and the surface layer contains alumina.
In this case, the silica layer has a surface layer or an intermediate layer containing alumina, titania and / or zinc oxide due to a change in the amount of moisture adsorbed on the silica due to a change in temperature and humidity, which is a disadvantage of silica with excellent negative chargeability. Can be suppressed. Therefore, it is possible to suppress the environmental dependency of the charge amount due to the change in the moisture adsorption amount of silica. Furthermore, although titania and zinc oxide used for the intermediate layer have a weak negative chargeability, the environmental dependency of the charge amount is small, so that the silica can complement the defects in characteristics of each other.
Therefore, in addition to the effects shown in the items (1) and (2) above, (3) the environmental dependency of the charge amount can be further reduced.

-Other characteristics-
Next, other preferable characteristics of the external additive of the present invention will be described.
The external additive of the present invention preferably has a hydrophobic surface in order to improve negative chargeability and long-term environmental stability. As a method for hydrophobizing the surface of the external additive, a known water-repellent treatment method can be used. For example, a spray that sprays a treatment agent or a solution containing the treatment agent on external additive particles suspended in a gas phase. It can be processed by a dry method such as a dry method or a wet method in which the external additive particles are immersed in a solution containing a processing agent and dried. However, from the viewpoint that a uniform hydrophobic film can be formed on the surface of the external additive, a method of immersing the external additive particles in a solution containing a treatment agent such as a coupling agent and drying is more preferable.

Although there is no restriction | limiting in particular as a processing agent used for a hydrophobization process, For example, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. Of these, silane coupling agents are preferred.
As the silane coupling agent, for example, any of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used.

  Here, as the treating agent used for the surface treatment, for example, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrichlorosilane. Methoxysilane, diphenyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (Bistrimethylsilyl) acetamide, N, N-bis (trimethylsilyl) urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyl Rutrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyl Representative examples include diethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane.

  The amount of the processing agent used with respect to 100 parts by weight of the external additive particles depends on the particle size of the external additive, the specific surface area, and the type of the processing agent, but is within the range of 1 to 70 parts by weight. Preferably, the range of 5 to 60 parts by weight is more preferable.

In addition, as described above, the shape of the external additive of the present invention can be any shape such as a spherical shape or an indeterminate shape other than the needle shape, but as a particle size in the case of a spherical shape or an indefinite shape. Is preferably in the range of 5 to 200 nm.
If the particle size is less than 5 nm, the external additive is buried in the toner particle surface over time, and the durability of the polishing ability may be reduced. As described above, silica may be added to the core layer and the intermediate layer. In the case of the external additive having a three-layer structure used, the sustainability of the charging ability may be reduced.
On the other hand, when the particle diameter exceeds 200 nm, it is difficult to uniformly add and adhere the external additive to the toner particle surface, and it becomes difficult to fix the external additive to the toner particle surface, and the fluidity of the toner Deterioration may easily occur. Therefore, the particle size of the external additive of the present invention is more preferably in the range of 10 nm to 150 nm in consideration of the powder characteristics, particularly the reduction of adhesion and the improvement of fluidity.

  The method for synthesizing the external additive is not particularly limited, and a known liquid phase method or gas phase method can be used in combination. For example, for the synthesis of the particles to be the core layer and the formation of the intermediate layer and the surface layer that covers the core layer, a fine particle synthesis method using the decomposition of compounds, hydrolysis of alkoxide, hydrolysis of metal ions, etc. Surface treatment methods can be used. Commercially available particles can also be used as the core layer particles, the core layer and intermediate layer particles in the case of producing a three-layer external additive, or the three-layer microparticles. .

For example, in the case of preparing an external additive having a three-layer structure in which the core layer is made of needle-like titania particles (or zinc oxide particles), the intermediate layer is made of silica, and the surface layer is made of alumina, JP-A-9-25429 is disclosed. Using the method described in the publication, it can be produced as follows.
Specifically, first, a slurry in which titania particles (or zinc oxide particles) having a needle shape are dispersed in an aqueous medium is maintained at 30 to 100 ° C., and a predetermined amount of an aqueous solution of a silica compound is added while maintaining a constant pH. Or after adding an aqueous solution of silica compound and neutralizing, or after adding an acid necessary for neutralization in advance, and then adding an aqueous solution of silica compound to precipitate the hydrous oxide of silicon, then necessary If there is, ripen for 30 to 90 minutes.
Then, gradually add an aqueous solution of an aluminum compound while maintaining a constant pH, or neutralize after adding an aqueous solution of a silica compound, or add an acid necessary for neutralization in advance, After the aqueous solution is added to precipitate the hydrated oxide of silicon, if necessary, aging is performed for 30 to 90 minutes, followed by filtration, washing with water, drying, pulverization, and mastering.
The silica compound that can be used in such a process is generally sodium silicate, but potassium silicate may also be used.
In addition, as the aluminum compound, aluminum sulfate, aluminum chloride, aluminum nitrate, sodium amate, and the like can be used. The acid used for neutralization includes nitric acid, hydrochloric acid, sulfuric acid and the like, and the alkali includes sodium hydroxide, potassium hydroxide and ammonium hydroxide.

(Electrophotographic toner)
The electrophotographic toner of the present invention (hereinafter sometimes abbreviated as “toner”) contains toner particles and the external additive for toner of the present invention externally added to the surface of the toner particles. Depending on the type, other types of external additives can also be added.
In the present invention, a toner body other than the external additive is referred to as “toner particle”, and a case including the toner particle and the external additive is referred to as “toner (or for electrophotography). Toner) ”.

  Here, as the toner particles themselves, known ones can be used. Specifically, toner particles containing a binder resin and a colorant, and containing a release agent and other components as required can be used. Hereinafter, the toner of the present invention will be described in more detail.

-Binder resin-
As the binder resin used for the toner particles, a known resin can be used. However, from the viewpoint of obtaining excellent low-temperature fixability, it is preferable to use a crystalline resin, and a crystalline resin and an amorphous resin are used in combination. It is also preferable.
Binder resins include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; methyl acrylate , Α-methylene aliphatic monocarboxylic acid esters such as ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl Homopolymers and copolymers of vinyl ethers such as methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone; Typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include coalescence, polyethylene, and polypropylene. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.
Among these, styrene-alkyl acrylate copolymers and styrene-alkyl methacrylate copolymers are particularly preferable.

  Specific examples of crystalline resins include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, tridecanedioic acid and other long-chain alkyl dicarboxylic acids, butanediol, pentanediol, and hexane. Polyester resins using diols such as diol, heptanediol, octanediol, nonanediol, decanediol, batyl alcohol and other long-chain alkyl and alkenyl diols; amyl (meth) acrylate, hexyl (meth) acrylate, (meth) acrylic Heptyl acid, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, tridecyl (meth) acrylate, myristyl (meth) acrylate, (meth) acrylic acid Cetyl, (meth) acrylic acid And vinyl resins using long-chain alkyls such as ryl, oleyl (meth) acrylate, and behenyl (meth) acrylate, and (meth) acrylic esters of alkenyl; and the like, to a recording medium such as paper at the time of fixing. Polyester resin based crystalline resins are preferred from the standpoints of adhesion, chargeability, and ease of adjusting the melting point within a desired range.

The melting point of the crystalline resin is preferably in the range of 50 to 180 ° C, and more preferably in the range of 60 to 150 ° C. When the melting point is lower than 50 ° C., the storage stability of the toner and the storage stability of the image after fixing may be deteriorated. On the other hand, if the temperature is higher than 180 ° C., the energy required for fixing increases and the power consumption of the apparatus may increase.
The crystalline resin may show a plurality of melting peaks, but in the present invention, the maximum peak is regarded as the melting point.
For measurement of the glass transition temperature (Tg) and melting point (Tm) of the binder resin, DSC-7 (differential thermal analyzer) manufactured by PerkinElmer was used. The temperature correction of the detection part of the apparatus uses the melting points of indium and zinc, and the correction of heat quantity uses the heat of fusion of indium. For the sample, an aluminum pan is used, and an empty pan is set as a control, and measurement is performed at a heating rate of 10 ° C./min. For calculation of the peak area of the molecular weight, the peak area is sliced for each retention time range, and the distribution ratio is obtained from the area ratio.

-Colorant-
The colorant is not particularly limited and may be either a dye or a pigment, but a pigment is preferable from the viewpoint of light resistance and water resistance.
Preferred pigments include carbon black, aniline black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, Quinacridone, benzidine yellow, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 185, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 74, C.I. I. Pigment blue 15: 1, C.I. I. A known pigment such as CI Pigment Blue 15: 3 can be used.
Magnetic powder can also be used as a colorant. As the magnetic powder, known magnetic materials such as ferromagnetic metals such as cobalt, iron and nickel, alloys and oxides of metals such as cobalt, iron, nickel, aluminum, lead, magnesium, zinc and manganese can be used.
The above colorants can be used alone or in combination of two or more. The content of the colorant contained in the toner of the present invention is preferably 0.1 to 40 parts by weight, more preferably 1 to 30 parts by weight with respect to 100 parts by weight of the toner particles. In addition, each color toner such as yellow toner, magenta toner, cyan toner, and black toner can be obtained by appropriately selecting the type of colorant.

-Other internal components-
Other components such as a release agent and a charge control agent may be internally added to the toner particles as necessary.
Generally as a mold release agent, it uses for the purpose of improving mold release property. Specific examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones having a softening point by heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide Plant waxes such as carnauba wax, rice wax, candelilla wax, wood wax, jojoba oil; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, etc. Mineral / petroleum waxes; ester waxes such as fatty acid esters, montanic acid esters, and carboxylic acid esters. In this invention, these mold release agents may be used individually by 1 type, and may use 2 or more types together.

The content of the release agent is preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight with respect to 100 parts by weight of the toner particles. If the amount is less than 1 part by weight, there is no effect of adding a release agent. If the amount exceeds 20 parts by weight, an adverse effect on the chargeability tends to appear, and the toner is easily destroyed inside the developing machine. In addition to the effect that the resin is spent on the carrier and the charge is likely to be lowered, for example, when color toner is used, the image surface tends to be insufficiently oozed out at the time of fixing. In some cases, the release agent tends to stay therein, so that the transparency is deteriorated, which is not preferable.
The melting point of the release agent is preferably 50 to 120 ° C, more preferably 60 to 100 ° C. If the melting point of the release agent is less than 60 ° C., the change temperature of the release agent is too low, and the blocking resistance may be inferior, or the developability may deteriorate when the temperature in the copying machine increases.

  The charge control agent is generally used for the purpose of improving the chargeability. Examples of the charge control agent include metal-containing azo compounds such as chromium azo dyes, iron azo dyes, and aluminum azo dyes; salicylic acid metal complexes, nigrosine and quaternary ammonium salts.

-Other external additives-
In addition to the external additive of the present invention, conventionally known external additives can be used in combination with the toner of the present invention, if necessary.
Examples of these other external additives include known inorganic materials such as inorganic fine particles, charge control agents, lubricants, abrasives, and cleaning aids for the purpose of improving charging characteristics, powder characteristics, transfer characteristics, and cleaning characteristics. An external additive composed of fine particles and / or resin fine particles can be externally added to the toner particles.

Known inorganic fine particles can be used. Examples thereof include silica, titania, metatitanic acid, zinc oxide, zirconia, magnesia, calcium carbonate, magnesium carbonate, calcium phosphate, cerium oxide, and strontium titanate. Further, in order to adjust the polishing ability, alumina fine particles can be used together as necessary. When the particle size of the inorganic fine particles is small (generally when the particle size is 40 nm or less), the dispersibility is low and the powder fluidity tends to be lowered. For this reason, in the case of using such small-diameter inorganic fine particles, it is preferable to carry out a hydrophobization treatment in the same manner as the external additive of the present invention.
Examples of the resin fine particles include spherical particles such as PMMA (polymethyl methacrylate), nylon, melamine, benzoguanamine, and fluorine, and amorphous powders such as vinylidene chloride and fatty acid metal salts.

-Amount of external additive-
The amount of the external additive added to the toner particles is preferably in the range of 0.1% by weight to 5% by weight and in the range of 0.2% by weight to 2.0% by weight with respect to 100 parts by weight of the toner particles. More preferred.
If the addition amount is less than 0.1% by weight, the addition amount may be small, and toner filming may not be sufficiently suppressed. In addition, as described above, in the case of the external additive having a three-layer structure using silica for the core layer and the intermediate layer, the toner particle surface is often exposed, and sufficient charging characteristics may not be obtained.
On the other hand, if it exceeds 5% by weight, the coverage of the toner particle surface with the external additive becomes high, and other members in the image forming apparatus such as adhesion to the carrier by free external additive, filming on the photoreceptor, etc. Contamination may occur.
In addition, when using other external additives, although depending on the constitution and addition amount of the external additive of the present invention, the addition amount is within the range of about 0.1 wt% to 5.0 wt%. Preferably there is.

-Toner particle size-
The toner particles preferably have a small particle diameter for the purpose of improving the image quality. However, if the diameter is too small, development is difficult with the conventional system from the viewpoint of charging and fluidity. From such a viewpoint, the volume average particle diameter of the toner particles is preferably in the range of 2 to 8 μm, and more preferably in the range of 4 to 7 μm.
When the volume average particle diameter of the toner particles exceeds 8 μm, the image quality such as fine line reproducibility and halftone granularity deteriorates, and it may be difficult to obtain good image quality when outputting photographic image quality. . Further, when the volume average particle diameter of the toner particles is less than 2 μm, the powder characteristics and the charging characteristics are very deteriorated, and it may be difficult to output at high speed by the conventional image forming apparatus.
Further, the value of volume average particle size / number average particle size as an index of particle size distribution is preferably 1.6 or less, and more preferably 1.5 or less. When this value is larger than 1.6, the spread of the particle size distribution becomes large, so that the distribution of the charge amount becomes wide, and reverse polarity toner and low-charge toner are likely to be generated.

In the present invention, the volume average particle size (cumulative volume average particle size D ₅₀ ), number average particle size (cumulative number average particle size D _50P ), and various particle size distribution indices are, for example, Coulter Counter TAII (Beckman-Coulter Company) The electrolyte can be measured using ISOTON-II (manufactured by Beckman-Coulter) using a measuring instrument such as Multisizer II (manufactured by Beckman-Coulter).
In the measurement, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant. This is added to 100-150 ml of electrolyte.
The electrolyte in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size of particles having a particle diameter in the range of 2 to 60 μm using the Coulter counter TA-II type with an aperture diameter of 100 μm. Measure the distribution. The number of particles to be sampled is 50,000.
For the particle size range (channel) divided on the basis of the particle size distribution measured in this way, the cumulative distribution is drawn from the smaller diameter side for the volume and number, respectively, and the cumulative particle size average particle size is 16%. Diameter D _16v , cumulative number average particle size D _16P , cumulative volume average particle size D _50v , cumulative number average particle size D _50P , cumulative number average particle size D _50P , cumulative particle size average particle size D _84v , cumulative number average particle size D _84P .
Using these, the volume average particle size distribution index (GSDv) is calculated as (D _84v / D _16V ) ^1/2 , and the number average particle size distribution index (GSDp) is calculated as (D _84P / D _16P ) ^1/2 .

-Toner production method-
For the production of toner particles, a known wet method or dry method can be used. For example, a binder resin, a colorant, and, if necessary, a release agent, a charge control agent, and the like are kneaded, pulverized, and classified. A kneading and pulverizing method; a method of changing the shape of particles obtained by the kneading and pulverizing method by mechanical impact force or thermal energy; an emulsion polymerization of a polymerizable monomer of a binder resin, and a dispersion formed; An emulsion polymerization aggregation method in which a dispersion liquid in which a colorant is dispersed and a dispersion liquid such as a release agent and a charge control agent used as necessary are mixed, aggregated, and heat-fused to obtain toner particles; Suspension polymerization method in which a polymerizable monomer for obtaining a binder resin, a colorant, and, if necessary, a solution of a release agent, a charge control agent, etc. are suspended in an aqueous solvent for polymerization; Granulation by suspending resin, colorant and, if necessary, solution of release agent, charge control agent, etc. in aqueous solvent And the like can be used; dissolution suspension method that.
In addition, toner particles obtained by the above method can be used as a core, and resin particles can be further adhered, and then heat-fused to produce a toner having a core-shell structure.

Subsequently, the toner of the present invention can be obtained by adding and mixing the external additive of the present invention and, if necessary, other external additives to the toner particles thus obtained.
The mixing of the toner particles and the external additive can be performed by a known method, for example, a V blender, a Henshur mixer, a Ladyge mixer or the like. Furthermore, if necessary, the toner obtained using a vibration classifier, a wind classifier, or the like may be classified to remove coarse particles.

(Electrophotographic developer)
The developer for electrophotography of the present invention is not particularly limited as long as it contains the toner of the present invention. Specifically, the one-component developer comprising only the toner of the present invention, or the toner and carrier of the present invention. Any of two-component developers consisting of
As the carrier, it is preferable in terms of charge controllability and resistance controllability to use a resin-coated carrier having a resin coating layer in which a conductive material is dispersed and contained in a matrix resin on a core material. As an average particle diameter of a carrier core material, generally 10-100 micrometers is preferable and 20-80 micrometers is more preferable. If it is smaller than 10 μm, the magnetic force per carrier particle may be reduced, and carrier jump may easily occur. If it is larger than 100 μm, there may be a problem that sufficient charge cannot be imparted to the toner or the image deteriorates.
The core material of the carrier is not particularly limited, and examples thereof include magnetic metals such as iron, steel, nickel and cobalt, magnetic oxides such as ferrite and magnetite, glass beads, and the like, from the viewpoint of using the magnetic brush method. Is preferably a magnetic carrier.

Coating resins include polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid copolymer Examples thereof include straight silicone resins composed of coalesced or organosiloxane bonds or modified products thereof, fluororesins, polyesters, polyurethanes, polycarbonates, phenol resins, amino resins, melamine resins, benzoguanamine resins, urea resins, amide resins, epoxy resins, etc. However, it is not limited to these.
The average film thickness of the resin coating layer formed by the above method is usually 0.1 to 10 μm, preferably 0.2 to 5 μm. When the thickness is 0.1 μm or less, the core is easily peeled off and the core is easily exposed over time, and the charge imparting ability and the resistance may be lowered, and a stable image quality may not be obtained. When the film thickness is 10 μm or more, the change with time does not easily occur, but the resistance becomes too high, so that the image quality may deteriorate or the fluidity may deteriorate.

In order to reduce the resistance while increasing the film thickness, the resin matrix may contain conductive powder. Examples of the conductive material include metals such as gold, silver and copper, and titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, carbon black, magnetite, and the like. Is not to be done.
The content of the conductive material is preferably 1 to 50 parts by weight and more preferably 3 to 20 parts by weight with respect to 100 parts by weight of the matrix resin.
If the carrier resistance is too low, the carrier adheres to the image area of the photoreceptor due to charge injection from the sleeve, or the latent image charge escapes through the carrier, resulting in a latent image distortion or image loss. Such a problem may occur. On the other hand, when the carrier resistance is high, the carrier charge is less likely to leak, resulting in an edged image, but on the other hand, the edge effect is that the image density at the center is very thin on a large image area. May arise.

  Examples of the method for producing the carrier include an immersion method in which the powder of the carrier core material is immersed in a solution for forming the coating layer, a spray method in which the solution for forming the coating layer is sprayed on the surface of the carrier core material, and the carrier core material is fluidized air. The fluidized bed method in which the coating layer forming solution is sprayed in a suspended state, the kneader coater method in which the carrier core material and the coating layer forming solution are mixed in the kneader coater to remove the solvent, and the coating resin is made into fine particles. Examples of the powder coating method include a carrier core material and a kneader coater which are mixed at a melting point or higher and cooled to form a film, and the kneader coater method and the powder coat method are particularly preferably used.

  The mixing ratio (weight ratio) between the toner of the present invention and the carrier in the two-component developer is in the range of toner: carrier = 1: 100 to 30: 100, and in the range of 3: 100 to 20: 100. Is more preferable.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the following description, “parts” means “parts by weight” unless otherwise specified.

-Preparation of toner-
[Manufacture of toner particles]
(Adjustment of resin fine particle dispersion)
A solution obtained by mixing 370 parts of styrene, 30 parts of n-butyl acrylate, 8 parts of acrylic acid, 24 parts of dodecanethiol, and 4 parts of carbon tetrabromide was dissolved in a nonionic surfactant (Nonipol 400: Sanyo Chemical Co., Ltd. )) 6 parts and 10 parts of anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were added to a flask filled with a solution prepared by dissolving 550 parts of ion-exchanged water, followed by emulsion polymerization for 10 minutes. While slowly mixing, 50 parts of ion-exchanged water having 4 parts of ammonium persulfate dissolved therein was added thereto.
Subsequently, the inside of the flask was purged with nitrogen, and then the emulsion was heated in an oil bath while stirring the flask until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours. As a result, a resin fine particle dispersion in which resin particles having a volume average particle size of 150 nm, a glass transition temperature Tg of 52 ° C., and a weight average molecular weight Mw of 10500 is obtained. The solid content concentration of this dispersion was 40% by weight.

(Adjustment of colorant dispersion (1))
Carbon black (Mogal L: Cabot): 60 parts Nonionic surfactant (Nonipol 400: Sanyo Chemical Co., Ltd.): 6 parts Ion-exchanged water: 240 parts After mixing and dissolving the above ingredients, homogenizer (Ultra Turrax T50: manufactured by IKA) for 10 minutes, and then dispersed with a optimizer to disperse colorant (carbon black) particles having an average particle diameter of 250 nm. (1) was adjusted.

(Adjustment of colorant dispersion (2))
-Cyan pigment (CI Pigment Blue-15: 3): 60 parts-Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.): 5 parts-Ion-exchanged water: 240 parts -After dissolution, the mixture is stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA) and then dispersed with an optimizer to disperse colorant (Cyan pigment) particles having an average particle size of 250 nm. A colorant dispersant (2) was prepared.

(Adjustment of colorant dispersion (3))
・ Magenta pigment (CI Pigment Red-122): 60 parts ・ Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.): 5 parts ・ Ion-exchanged water: 240 parts The above ingredients are mixed and dissolved. Thereafter, the mixture was stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then dispersed with an optimizer to disperse colorant (Magenta pigment) particles having an average particle diameter of 250 nm. An agent dispersant (3) was prepared.

(Adjustment of colored dispersion (4))
Yellow pigment (CI Pigment Yellow-180): 90 parts Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.): 5 parts Ion-exchanged water: 240 parts The above ingredients are mixed and dissolved Thereafter, the mixture was stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then dispersed with an optimizer to disperse colorant (Yellow pigment) particles having an average particle diameter of 250 nm. An agent dispersant (4) was prepared.
In addition, the colorant particle size of each obtained colorant dispersion was measured with a laser diffraction particle size distribution measuring apparatus (LA-700, manufactured by Horiba, Ltd.).

(Adjustment of release agent dispersion)
Paraffin wax (HNP0190: Nippon Seiwa Co., Ltd., melting point 85 ° C.): 100 parts Cationic surfactant (Sanisol B50: Kao Corporation): 5 parts Ion-exchanged water: 240 parts Is dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA) for 10 minutes, and then dispersed with a pressure discharge type homogenizer, and the release agent particles having an average particle diameter of 550 nm A release agent dispersion in which was dispersed was prepared.
The release agent particle size of the obtained release agent dispersion was measured with a laser diffraction particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.).

(Adjustment of toner particles K1)
-Resin fine particle dispersion: 234 parts-Colorant dispersion (1): 30 parts-Release agent dispersion: 50 parts-Polyaluminum hydroxide (Pho2S manufactured by Asada Chemical Co., Ltd.): 0.5 parts-Ion exchange water : 600 parts The above components were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then stirred at 40 ° C while stirring the flask in an oil bath for heating. Until heated.
After keeping the inside of the flask at 40 ° C. for 30 minutes, it was confirmed that aggregated particles having a volume average particle diameter of 4.5 μm were generated. Further, the temperature of the heating oil bath was raised and maintained at 56 ° C. for 1 hour, and then the volume average particle diameter of the aggregated particles was confirmed to be 5.3 μm.
Thereafter, 26 parts by weight of the resin fine particle dispersion was added to the dispersion containing the aggregate particles, and then the temperature of the heating oil bath was raised to 50 ° C. and held for 30 minutes. After adding a 1N sodium hydroxide solution to the dispersion containing the aggregated particles and adjusting the pH of the dispersion in the flask to 7.0, the flask is sealed and stirring is continued using a magnetic seal. The mixture was heated to 80 ° C. and held for 4 hours.
After cooling, the toner particles were filtered off, washed four times with ion exchange water, and then lyophilized to obtain toner particles K1. The toner particles K1 have a volume average particle size of 5.9 μm and an average shape factor ML2 / A of 132.

The shape factor ML2 / A means a value defined by the following formula (1).
Formula (1) ML2 / A = ((absolute maximum length of toner particles) ² / projection area of toner particles) × (π / 4) × 100
The absolute maximum length of the toner particles represented by the formula (1) and the projected area of the toner particles were obtained by photographing a toner particle image magnified 500 times using an optical microscope (Nikon, Microphoto-FXA). The information was obtained by introducing the information into an image analysis apparatus (Luzex III) manufactured by Nireco through an interface and performing image analysis.
Here, the value of the average shape factor ML2 / A was calculated as an average value based on data obtained by measuring 1000 toner particles sampled randomly.

(Adjustment of toner particles C1)
Toner particles C1 were obtained in the same manner as in the adjustment of the toner particles K1, except that the colored particle dispersion (2) was used instead of the colored particle dispersion (1). The volume average particle diameter of the toner particles C1 is 5.8 μm, and the average shape factor ML2 / A is 131.

(Adjustment of toner particles M1)
Toner particles M1 were obtained in the same manner as the adjustment of toner particles K1, except that the colored particle dispersion (3) was used instead of the colored particle dispersion (1). The toner particles M1 have a volume average particle size of 5.5 μm and an average shape factor ML2 / A of 135.

(Adjustment of toner particles Y1)
Toner particles Y1 were obtained in the same manner as the adjustment of toner particles K1, except that the colored particle dispersion (4) was used instead of the colored particle dispersion (1). The toner particles Y1 have a volume average particle size of 5.9 μm and an average shape factor ML2 / A of 130.

-Fabrication of carrier-
14 parts of toluene, 2 parts of styrene-methyl methacrylate copolymer (monomer component ratio: styrene / methyl methacrylate = 80/20), and 0.2 part of carbon black (R330: manufactured by Cabot) were mixed and stirred for 10 minutes. To prepare a coating layer forming solution in which carbon black is dispersed.
Next, 3 parts of this coating layer forming solution and 100 parts of ferrite particles (volume average particle size: 38 μm) were placed in a vacuum degassing kneader and stirred for 30 minutes at 60 ° C. The carrier was prepared by deaeration and drying. This carrier had a volume resistivity of 10 ¹¹ Ωcm when an electric field of 800 V / cm was applied.

-Preparation of external additives-
(Adjustment of external additive (1))
In a reaction container filled with a mixed solvent in which 1000 parts by weight of pure water and 100 parts by weight of 2-propanol are mixed, the core layer is made of titania, the intermediate layer is made of silica, and the surface layer is made of alumina. 80 parts by weight of acicular fine particles (trade name “STR-100A-LP”, manufactured by Sakai Chemical Industry Co., Ltd.) having a diameter of 20 nm and a major axis of 100 nm were added to form a slurry.
Next, 10 parts by weight of trimethyldecylsilane (trade name “KBM3103”, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 150 parts by weight of the slurry in which the fine particles were dispersed in a solvent.
Subsequently, after replacing the inside of the reaction vessel with dry nitrogen gas, the temperature was raised to 80 ° C., 30 parts by weight of 0.1N hydrochloric acid solution was dropped, and the mixed solution in the reaction vessel was stirred under a nitrogen gas stream. The temperature was raised to about 80 ° C.

Thereafter, the reaction was stirred for 3 hours while heating and refluxing in an oil bath. After cooling, the mixed solution was taken out from the reaction vessel, and fine particles were separated by a centrifuge and the supernatant was removed. The operation of mixing and stirring the fine particles filtered in this manner with a 10% aqueous methanol solution and repeating the centrifugation three times, and further mixing and stirring with pure water, repeating the centrifugal operation three times, and then absorbing the fine particles. The water was removed by freeze-drying.
Subsequently, the fine particles were vacuum-dried at 160 ° C. for 2 hours, then crushed in an agate mortar, and sieved with a 40 μm sieve mesh to obtain external additive (1).

(Adjustment of external additive (2))
A reaction vessel was charged with 1000 parts by weight of pure water and 100 parts by weight of titania (trade name STR-60, manufactured by Sakai Chemical Industry Co., Ltd.) having a needle shape with a minor axis of 23 nm and a major axis of 80 nm. did.
The slurry was heated to 80 ° C. with stirring, and 6 parts by weight of an aqueous sodium silicate solution was added to 200 parts by weight of the solid content (titania fine particles) in the slurry while maintaining the pH at 4 with dilute sulfuric acid. After the oxide was precipitated, it was further aged for 60 minutes.
Subsequently, 3 parts by weight of an aluminum nitrate aqueous solution was added to 150 parts by weight of the solid content (titania fine particles) in the slurry while maintaining the temperature at 80 ° C., and then adjusted to pH 7.5 by adding an aqueous sodium hydroxide solution. After precipitation of aluminum-containing hydroxide, the mixture was aged for 2 hours.
The slurry obtained through such treatment is washed with filtered water, and the obtained solid content is dried and then pulverized. The core layer is composed of titania, the intermediate layer is composed of silica, and the surface layer is composed of alumina. Fine particles having a needle shape and a minor axis of 30 nm and a major axis of 90 nm were obtained.
The fine particles thus obtained were subjected to the same hydrophobizing treatment as that of the external additive (1) to obtain the external additive (2).

(Adjustment of external additive (3))
In a reaction vessel, 1000 parts by weight of pure water and 100 parts by weight of titania (trade name STR-30, manufactured by Sakai Chemical Industry Co., Ltd.) having a spherical shape with a particle size of 50 nm were added and mixed to form a slurry.
The slurry was heated to 80 ° C. with stirring, and 6 parts by weight of an aqueous sodium silicate solution was added to 200 parts by weight of the solid content (titania fine particles) in the slurry while maintaining the pH at 4 with dilute sulfuric acid. The oxide was precipitated and aged for 60 minutes.
Subsequently, 3 parts by weight of an aluminum nitrate aqueous solution was added to 150 parts by weight of the solid content (titania fine particles) in the slurry while maintaining the temperature at 80 ° C., and then adjusted to pH 7.5 by adding an aqueous sodium hydroxide solution. Then, the aluminum hydrated oxide was precipitated and aged for 2 hours.
The slurry obtained through such treatment is washed with filtered water, and the obtained solid content is dried and then pulverized. The core layer is composed of titania, the intermediate layer is composed of silica, and the surface layer is composed of alumina. Spherical fine particles having a particle diameter of 60 nm were obtained.
The fine particles thus obtained were subjected to the same hydrophobic treatment as that of the external additive (1) to obtain the external additive (3).

(Adjustment of external additive (4))
External additive (1) for fine particles (trade name STR-100C-LP, manufactured by Sakai Chemical Industry Co., Ltd.) having a core-shell structure in which titania is coated with alumina and having a minor axis of 20 nm and a major axis of 100 nm. The same hydrophobic treatment was performed to obtain an external additive (4).

(Adjustment of external additive (5))
Similar to the external additive (1) for fine particles (trade name STR-100W, manufactured by Sakai Chemical Industry Co., Ltd.) having a core-shell structure in which titania is coated with silica and having a short diameter of 20 nm and a long diameter of 100 nm. Hydrophobization treatment was performed to obtain an external additive (5).

(Adjustment of external additive (6))
Hydrophobic treatment similar to that of the external additive (1) was performed on alumina fine particles having an average particle diameter of 13 nm (trade name: AOC, manufactured by Nippon Aerosil Co., Ltd.) to obtain an external additive (6).

(Adjustment of external additive (7))
In a reaction vessel filled with a mixed solvent in which 1000 parts by weight of pure water and 100 parts by weight of 2-propanol are mixed, the average particle size is a three-layer structure in which the core layer is zinc oxide, the intermediate layer is silica, and the surface layer is alumina. 80 parts by weight of spherical fine particles having a diameter of 20 nm (trade name “NONOFINE-50A”, manufactured by Sakai Chemical Industry Co., Ltd.) were added to form a slurry.
Next, 10 parts by weight of trimethyldecylsilane (trade name “KBM3103”, manufactured by Shin-Etsu Chemical Co., Ltd.) was charged into a reaction vessel with respect to 200 parts by weight of the slurry in which the fine particles were dispersed in a solvent.
Subsequently, after replacing the inside of the reaction vessel with dry nitrogen gas, the temperature was raised to 80 ° C., 30 parts by weight of 0.1N hydrochloric acid solution was dropped, and the mixed solution in the reaction vessel was stirred under a nitrogen gas stream. The temperature was raised to about 80 ° C.

Thereafter, the reaction was stirred for 3 hours while heating and refluxing in an oil bath. After cooling, the mixed solution was taken out from the reaction vessel, and fine particles were separated by a centrifuge and the supernatant was removed. The operation of mixing and stirring the fine particles filtered in this manner with a 10% aqueous methanol solution and repeating the centrifugation three times, and further mixing and stirring with pure water, repeating the centrifugal operation three times, and then absorbing the fine particles. The water was removed by freeze-drying.
Subsequently, the fine particles were vacuum-dried at 160 ° C. for 2 hours, then crushed in an agate mortar, and sieved with a 40 μm sieve mesh to obtain an external additive (7).

(Adjustment of external additive (8))
In a reaction vessel, 1000 parts by weight of pure water and 100 parts by weight of zinc oxide fine particles (trade name FINEX-50, manufactured by Sakai Chemical Industry Co., Ltd.) having an average particle diameter of 20 nm were mixed to form a slurry.
The slurry was heated to 80 ° C. with stirring, and 3 parts by weight of an aqueous aluminum sulfate solution was added to 150 parts by weight of the solid content (zinc oxide fine particles) while maintaining the pH at 4 with dilute sulfuric acid. An aqueous solution was added to adjust the pH to 7.5 to precipitate aluminum hydrated oxide, followed by further aging for 2 hours.
Next, the slurry was washed with filtered water and dried, and the solid material obtained was pulverized to obtain fine particles having a core-shell structure in which zinc oxide was coated with alumina.
The fine particles thus obtained were subjected to the same hydrophobizing treatment as the external additive (1) and used as the external additive (8).

(Adjustment of external additive (9))
Hydrophobic treatment similar to external additive (1) is applied to fine particles (trade name FINEX-50W-LP2, manufactured by Sakai Chemical Industry Co., Ltd.) having a core-shell structure in which zinc oxide is coated with silica and having an average particle diameter of 20 nm. Used as external additive (9).

(Adjustment of external additive (10))
A reaction vessel was charged with 1000 parts by weight of pure water and 100 parts by weight of silica fine particles having an average particle size of 30 nm (trade name A50, manufactured by Sakai Chemical Industry Co., Ltd.) and mixed to form a slurry.
The slurry was heated to 80 ° C. with stirring, and 3 parts by weight of an aqueous aluminum sulfate solution was added to 150 parts by weight of solid content (silica fine particles) while maintaining the pH at 4 with dilute sulfuric acid. Was added to adjust the pH to 7.5, and a hydrous oxide of aluminum was precipitated, followed by aging for 2 hours.
Next, the slurry was washed with filtered water and dried, and the solid material obtained was pulverized to obtain fine particles having a core-shell structure in which silica was coated with alumina.
The fine particles thus obtained were subjected to the same hydrophobizing treatment as the external additive (1) and used as the external additive (10).

(Adjustment of external additive (11))
A reaction vessel was charged with 1000 parts by weight of pure water and 100 parts by weight of silica fine particles (trade name A50, manufactured by Sakai Chemical Industry Co., Ltd.) having an average particle size of 30 nm to form a slurry.
The slurry was heated to 80 ° C. with stirring, and 6 parts by weight of titanium sulfate aqueous solution was added to 200 parts by weight of the solid content (silica fine particles) in the slurry while maintaining the pH at 4 with dilute sulfuric acid. After precipitation, the product was aged for another 60 minutes.
Subsequently, 3 parts by weight of an aluminum nitrate aqueous solution was added to 150 parts by weight of the solid content (titania fine particles) in the slurry while maintaining the temperature at 80 ° C., and then adjusted to pH 7.5 by adding an aqueous sodium hydroxide solution. After precipitation of aluminum-containing hydroxide, the mixture was aged for 2 hours.
The slurry obtained through such treatment is washed with filtered water, and the resulting solid content is dried and then pulverized. The core layer is made of silica, the intermediate layer is titania, and the surface layer is made of alumina. Fine particles having a spherical shape and an average particle diameter of 40 nm were obtained.
The fine particles thus obtained were subjected to the same hydrophobic treatment as that of the external additive (1) to obtain the external additive (11).

(Adjustment of external additive (12))
A reaction vessel was charged with 1000 parts by weight of pure water and 100 parts by weight of silica fine particles (trade name A50, manufactured by Sakai Chemical Industry Co., Ltd.) having an average particle size of 30 nm to form a slurry.
The slurry was heated to 80 ° C. with stirring, and 6 parts by weight of titanium sulfate aqueous solution was added to 200 parts by weight of the solid content (silica fine particles) in the slurry while maintaining the pH at 4 with dilute sulfuric acid. After precipitation, the product was aged for another 60 minutes.
Subsequently, after adding 3 parts by weight of the zinc sulfate aqueous solution to 150 parts by weight of the solid content (titania fine particles) in the slurry while maintaining the temperature at 80 ° C., the pH is adjusted to 7.5 by adding an aqueous sodium hydroxide solution. Then, after precipitation of a hydroxide containing zinc, the mixture was aged for 2 hours.
The slurry obtained through such treatment is washed with filtered water, and the obtained solid content is dried and then pulverized. The core layer is made of silica, the intermediate layer is made of zinc oxide, and the surface layer is made of alumina. Obtained spherical particles having a particle diameter of 40 nm.
The fine particles thus obtained were subjected to the same hydrophobizing treatment as that of the external additive (1) to obtain the external additive (12).

Example 1
To each 100 parts of toner particles Y1, M1, C1, and K1, 1.5 parts by weight of the external additive (1) was added, and a peripheral speed of 30 m. After blending for 15 minutes at / s, coarse particles were removed using a sieve having an opening of 45 μm to prepare a toner.
Subsequently, 8 parts of the obtained toner of each color and 100 parts of the carrier were stirred for 20 minutes at 40 rpm with a V-blender, and sieved with a sieve having an opening of 212 μm, thereby developing developer (1). Obtained.

(Example 2)
A developer was prepared in the same manner as in Example 1 except that the external additive (2) was used in place of the external additive (1) to obtain a developer (2).

(Example 3)
A developer was prepared in the same manner as in Example 1 except that the external additive (3) was used in place of the external additive (1) to obtain a developer (3).

Example 4
A developer was prepared in the same manner as in Example 1 except that the external additive (4) was used in place of the external additive (1) to obtain a developer (4).

(Comparative Example 1)
A developer was produced in the same manner as in Example 1 except that the external additive (5) was used in place of the external additive (1) to obtain a developer (5).

(Comparative Example 2)
A developer was produced in the same manner as in Example 1 except that the external additive (9) was used in place of the external additive (1) to obtain a developer (9).

(Example 5)
A developer was produced in the same manner as in Example 1 except that the external additive (7) was used in place of the external additive (1) to obtain a developer (7).

(Example 6)
A developer was produced in the same manner as in Example 1 except that the external additive (8) was used in place of the external additive (1) to obtain a developer (8).

(Comparative Example 3)
A developer was prepared in the same manner as in Example 1 except that the external additive (10) was used in place of the external additive (1) to obtain a developer (9).

(Comparative Example 4)
A developer was produced in the same manner as in Example 1 except that the external additive (6) was used in place of the external additive (1) to obtain a developer (10).

(Example 7)
A developer was produced in the same manner as in Example 1 except that the external additive (11) was used in place of the external additive (1) to obtain a developer (11).

(Example 8)
A developer was produced in the same manner as in Example 1 except that the external additive (12) was used instead of the external additive (1) to obtain a developer (12).

-Evaluation-
Using each developer obtained, an image was formed using a modified DocuCentreColor400 (Fuji Xerox Co., Ltd.), and the photoreceptor wear rate, color streak, image quality, and charging characteristics were evaluated. The results are shown in Tables 1 and 2 below.
In forming an image, a four-color gradation chart was used.
The gradation chart used is an A4 size chart (hereinafter referred to as “gradation chart A”) for each image density of 20% and an A4 size chart (hereinafter referred to as “gradation chart B” for each image density of 3%. The image density is adjusted by the area ratio of the image portion. Each gradation chart has a solid portion, a halftone portion, and a background portion.

<Photoreceptor wear rate evaluation and color streak evaluation>
The photoconductor after outputting 100,000 color charts in an environment of normal temperature and normal humidity (temperature 22 ° C., humidity 55%) is an eddy current film thickness meter, and the heat deflection temperature conforms to HDT 0.45 Mpa (ISO 75-2). 10 points were measured, and the photoreceptor wear rate was calculated from the average value of the amount of wear.
Here, the photoreceptor wear rate means the amount of wear of the photoreceptor for every 1000 sheets output, and the evaluation criteria shown in Table 2 are as follows.
A: Photoreceptor wear rate of less than 10 nm / 1000 sheets ○: Photoconductor wear rate of 10 nm / 1000 sheets or more, less than 15 nm / 1000 sheets Δ: Photoconductor wear rate of 15 nm / 1000 sheets or more, less than 20 nm / 1000 sheets ×: Photoconductor wear rate of 20 nm / 1000 sheets or more

<Color streak evaluation>
For the color streaks, the image quality after the photoreceptor wear rate was evaluated was visually observed to check for the occurrence of color streaks. The evaluation criteria shown in Table 2 are as follows.
○: Color streaks are not observed.
X: Color streaks were observed.

<Image quality evaluation>
The gradation chart A output under high temperature and high humidity (temperature 30 ° C., humidity 80%) and the gradation chart B output under low temperature and low humidity (temperature 8 ° C., humidity 10%) after 100 sheets and 10 Using the output chart after 1,000 sheets, the image density of the solid part and the fog (dirt) of the background part were evaluated.
Note that the image density of the solid portion and the fog of the background portion were measured using a spectrocolorimetric densitometer (X-Rite 938, manufactured by X-Rite), and the evaluation results showed only the cyan color. Here, the evaluation criteria shown in Table 2 are as follows.
-Image density evaluation criteria-
A: The density of the solid part is 1.6 or more. O: The density of the solid part is 1.4 or more and less than 1.6. Δ: The density of the solid part is 1.2 or more and less than 1.4. X: The density of the solid part is 1. Less than 2-Evaluation standard for fog-
A: Background portion density is less than 0.1 ○: Background portion concentration is 0.1 or more and less than 0.2 ×: Background portion density is 0.2 or more and less than 0.3 ×: Background portion density is 0.3 or more

<Charging characteristics evaluation>
Tone chart A is output under high temperature and high humidity (temperature 30 ° C., humidity 80%), and the developer on the mag roll after 100 sheets and the developer on the mag roll after 10,000 sheets are collected to measure the charge. Carried out. The evaluation results are shown only for Cyan. Also, the gradation chart B is output under low temperature and low humidity (temperature 8 ° C./humidity 10%), the developer on the mag roll after 100 sheets and the development on the mag roll after 10,000 sheets. The agent was sampled and the charge was measured.
In addition, the charge amount was measured using a blow-off measuring device (TB200 manufactured by Toshiba Chemical Co., Ltd.), and only Cyan was shown as the evaluation result.
The evaluation criteria for the environmental difference (charge amount ratio = charge amount under high temperature / high temperature environment / charge amount under low temperature / low temperature environment) shown in Table 1 are as follows.
-Evaluation criteria for environmental differences-
◎: Charge amount ratio is 0.8 or more ○: Charge amount ratio is 0.7 or more and less than 0.8 ×: Charge amount ratio is less than 0.7

Claims (11)

It consists of two or more layers including the surface layer,
An external additive for toner, wherein the surface layer has a Vickers hardness of 15 GPa or more, and at least one of the layers provided inside the surface layer has a Vickers hardness of 10 GPa or less. The surface layer, a core layer provided inside the surface layer, and an intermediate layer provided between the core layer and the surface layer,
The core layer has a Vickers hardness of 10 GPa or less,
The external additive for toner according to claim 1, wherein the volume resistance of the intermediate layer is 10 ¹⁵ Ω · cm or more.   The external additive for toner according to claim 2, wherein the core layer contains titania and / or zinc oxide, the intermediate layer contains silica, and the surface layer contains alumina.   The external additive for toner according to claim 3, wherein the shape is needle-shaped, and the core layer contains titania.   The external additive for toner according to claim 4, wherein the minor axis is in the range of 20 to 30 nm and the major axis is in the range of 80 to 120 nm. The surface layer, a core layer provided inside the surface layer, and an intermediate layer provided between the core layer and the surface layer,
The volume resistance of the core layer is 10 ¹⁵ Ω · cm or more,
The external additive for toner according to claim 1, wherein the intermediate layer has a Vickers hardness of 10 GPa or less.   7. The toner external additive according to claim 6, wherein the core layer contains silica, the intermediate layer contains titania and / or zinc oxide, and the surface layer contains alumina.   The external additive for toner according to claim 1, wherein the surface has hydrophobicity.   The external additive for toner according to any one of claims 1 to 8, wherein the surface is hydrophobized with alkoxysilane.   An electrophotographic toner comprising toner particles and the toner external additive according to any one of claims 1 to 9 externally added to the surface of the toner particles.   An electrophotographic developer comprising the electrophotographic toner according to claim 10.