JP2020012861A - Alumina for toner external addition - Google Patents

Abstract

To provide an alumina for toner external addition capable of enhancing the fluidity of toner compared to alumina where the crystal phase is the gamma phase.SOLUTION: Disclosed alumina for toner external addition has the main crystal phase in θ phase, δ phase, or κ phase. The alumina for toner external addition preferably has the pore volume of mesopores with a pore radius of 1.3 nm to 100 nm being preferably 1.5 mL/g or less. The alumina for toner external addition preferably has a hydrophobic layer on the surface. When the hydrophobic layer is provided, the BET specific surface area should be 40 m/g or more, and the water content is preferably 5.0% or less. The hydrophobized layer is preferably an alkoxysilane hydrophobized layer.SELECTED DRAWING: None

Description

  The present invention relates to alumina for external addition to toner.

  In an image forming apparatus, toner particles are used to visualize an electrostatic latent image and fix it on recording paper. The toner particles generally include resin particles serving as a base material and a colorant held by the resin particles, and further include a release agent, a charge control agent, an external additive, and the like. The external additive can be added from the viewpoint of controlling charge stability, fluidity, and the like of the toner particles. If the fluidity of the toner particles is high, the toner particles are less likely to agglomerate, and thus, for example, it becomes easier to supply toner from the cartridge to the developing device.

  Patent Document 1 discloses that alumina fine powder is used as the external additive. Patent Document 1 discloses that alumina having an α phase as a main crystal phase has high hardness, may damage the surface of the photoreceptor, and has insufficient fluidity. Discloses that preferred alumina is preferred.

JP 2008-145489 A

  However, the present inventors have studied and found that even alumina having a γ phase as a main crystal phase has insufficient fluidity. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an alumina for external addition to a toner, which can increase the fluidity of the toner as compared with alumina having a γ phase as a main crystal phase.

The present invention is as follows.
[1] Alumina for external addition to a toner in which a main crystal phase is a θ phase, a δ phase, or a κ phase.
[2] The alumina for external addition to toner according to [1], wherein the pore volume of mesopores having a pore radius of 1.3 nm to 100 nm is 1.5 mL / g or less.
[3] The alumina for external addition to a toner according to [1] or [2], which has a hydrophobic layer on the surface.
[4] The alumina for external addition to toner according to [3], wherein the alumina has a BET specific surface area of 40 m ² / g or more.
[5] The alumina for external addition to a toner according to [3] or [4], wherein the alumina content is 5.0% or less.
[6] The alumina for external addition to a toner according to any one of [3] to [5], wherein the hydrophobic layer is an alkoxysilane hydrophobic layer.

  According to the alumina for external addition of the toner of the present invention, the fluidity of the toner can be improved.

1. Alumina for External Addition of Toner The alumina for external addition of the toner of the present invention has a main crystal phase of a θ phase, a δ phase, or a κ phase. When the alumina is used as an external additive of the toner, the fluidity of the toner can be improved.

The main crystal phase of alumina is determined based on the CuKα characteristic X-ray diffraction pattern. The following peak intensities are compared, and the phase corresponding to the peak having the highest intensity is defined as the main crystal phase.
α phase: 2θ = 57.5 °
θ phase: 2θ = 32.7 °
δ phase: 2θ = 36.5 °
γ phase: 2θ = 45.4 °
κ phase: 2θ = 42.9 °

When the θ phase, δ phase, or κ phase is the main crystal phase, the alumina may also include the α phase, which is the most stable phase. The mixing ratio of the α phase is, for example, 40% or less, preferably 30% or less, more preferably 20% or less, still more preferably 10% or less, and still more preferably 5% or less. , 0%. The α-phase mixing ratio is obtained by the following equation.
α phase contamination rate (%) = (α phase peak intensity / main crystal phase peak intensity) × 100

The BET specific surface area of the alumina is, for example, 40 m ² / g or more, preferably 50 m ² / g or more, more preferably 60 m ² / g or more, for example, 150 m ² / g or less, preferably Is 130 m ² / g or less, more preferably 100 m ² / g or less.

  In the alumina, the pore volume of mesopores having a pore radius of 1.3 nm to 100 nm is, for example, 1.5 mL / g or less, preferably 1.3 mL / g or less, and more preferably 1. It is 1 mL / g or less. The pore volume of the mesopores may be, for example, 0.5 mL / g or more, 0.7 mL / g or more, or 0.9 mL / g or more.

  The average pore radius of the alumina is, for example, 10 nm or more, preferably 15 nm or more, more preferably 20 nm or more, for example, 100 nm or less, preferably 70 nm or less, more preferably 50 nm or less. It is.

  The volume-based average particle diameter (D50) of the alumina is, for example, 1 to 100 μm, preferably 3 to 50 μm, and more preferably 5 to 20 μm. Use of alumina having a particle diameter in the above range as a toner external additive can improve the fluidity of the toner.

  The water content of the alumina is, for example, 0.5% or more, preferably 0.7% or more, more preferably 1.0% or more, for example, 5.5% or less, and preferably 5.5% or less. It is at most 5.0%, more preferably at most 4.0%, even more preferably at most 3.5%. The use of alumina having a water content in the above range as the toner external additive can improve the charging stability of the toner.

The light bulk density of the alumina is, for example, 0.10 g / cm ³ or more, preferably 0.15 g / cm ³ or more, more preferably 0.18 g / cm ³ or more, for example, 0.35 g. / Cm ³ or less, preferably 0.30 g / cm ³ or less, more preferably 0.25 g / cm ³ or less. By setting the light bulk density within the above range, the surface treatment of alumina can be performed uniformly and efficiently.

Tamped density of the alumina is, for example, 0.15 g / cm ³ or more, preferably 0.20 g / cm ³ or more, more preferably 0.23 g / cm ³ or more, for example, 0. It is 40 g / cm ³ or less, preferably 0.35 g / cm ³ or less, more preferably 0.30 g / cm ³ or less. By setting the heavy bulk density within the above range, the surface treatment of alumina can be performed uniformly and efficiently.

  The alumina may have a hydrophobic layer on the surface. Examples of the hydrophobic layer include a hydrophobic layer formed by a surface treatment with a silane-based compound such as alkoxysilanes, acyloxysilanes, siloxane, silane, and silicone oil. As the hydrophobic layer, an alkoxysilane hydrophobic layer formed by surface treatment with alkoxysilanes is preferable.

  Examples of the alkoxysilanes include alkylalkoxysilanes; hydroxyalkylalkoxysilanes such as hydroxypropyltrimethoxysilane; and ethylenic double bonds such as vinyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloxypropyltrimethoxysilane. Examples include alkoxysilanes having a hydrocarbon group bonded thereto; arylalkoxysilanes such as phenylmethoxysilane, and the like, with alkylalkoxysilanes being preferred. The carbon number of the alkoxy group of the alkoxysilanes is, for example, about 1 to 10, preferably about 1 to 4, and more preferably 1 or 2.

  Examples of the alkylalkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, n-decyltrimethoxysilane, n-hexadecyltrimethoxysilane, n Alkyltrialkoxysilanes such as octadecyltrimethoxysilane; dialkyldialkoxysilanes such as dimethyldimethoxysilane and dimethyldiethoxysilane; and trialkylalkoxysilanes such as trimethylmethoxysilane. Alkyltrialkoxysilanes are preferred. 1-30 are preferable, as for carbon number of the alkyl group of the said alkylalkoxysilane, 2-20 are more preferable, 3-12 are more preferable, and 4-8 are still more preferable. As the number of carbon atoms in the alkyl group of the alkylalkoxysilane increases, the charging stability increases. When the number of carbon atoms increases, the alumina has a main crystal phase of a θ phase, a δ phase, or a κ phase, although the fluidity of the toner generally decreases. Shows high fluidity. When the main crystal phase of alumina is a θ phase, a δ phase, or a κ phase, by increasing the carbon number of the alkyl group of the alkylalkoxysilane in the hydrophobized layer, both charging stability and fluidity can be achieved at a high level. .

  The amount of the hydrophobic layer made of alumina having a hydrophobic layer on the surface can be adjusted by the covering ratio described in detail in Examples described later. The coverage is, for example, 20% or more, preferably 30% or more, more preferably 40% or more, for example, 80% or less, preferably 70% or less, more preferably 60% or less. % Or less.

  The degree of hydrophobicity of the alumina having a hydrophobic layer on the surface is, for example, 20% or more, preferably 30% or more, and more preferably 40% or more. The upper limit of the hydrophobicity is not particularly limited and may be 100%, for example, may be 90% or less, or may be 70% or less.

The BET specific surface area of the alumina having a hydrophobic layer on the surface is, for example, 40 m ² / g or more, preferably 50 m ² / g or more, and more preferably 60 m ² / g or more. When a hydrophobic layer is formed on the surface of alumina whose main crystal phase is the γ phase, the BET specific surface area tends to decrease. On the other hand, when the hydrophobic layer is formed on the surface of alumina whose main crystal phase is the θ phase, the δ phase, or the κ phase, the BET specific surface area is kept high. Therefore, when alumina whose main crystal phase is the θ phase, the δ phase, or the κ phase is used as an external additive of the toner, the fluidity of the toner can be improved. When a hydrophobized layer is formed on the surface of alumina whose main crystal phase is the θ phase, δ phase, or κ phase, the BET specific surface area is maintained at a high level without damaging pores in the particles. This is probably because the hydrophobic treatment is easy. The upper limit of the BET specific surface area of the alumina having a hydrophobic layer on the surface is not particularly limited, but may be, for example, 150 m ² / g or less, 130 m ² / g or less, or 100 m ² / g or less. It may be.

  The water content of the alumina having a hydrophobic layer on the surface is, for example, 0.2% or more, preferably 0.3% or more, more preferably 0.5% or more, for example, 5.0. % Or less, preferably 4.5% or less, more preferably 3.0% or less, still more preferably 2.0% or less, and still more preferably 1.5% or less.

The alumina can be used as an external additive of the toner. The performance as a toner external additive can be evaluated by using a simulated toner adjusted as follows.
Simulated toner: 0.1 g of alumina powder and 10 g of spherical particles of cross-linked poly (methyl methacrylate) (particle size: 8 μm, product name: SSX-108, manufactured by Sekisui Chemical Co., Ltd.) are mixed with a mixer (model A10, manufactured by IKA). Stir and mix for minutes.

  The fluidity of the simulated toner when the alumina is used as an external additive is, for example, 90% or more, preferably 92% or more, and more preferably 95% or more. The fluidity means that the simulated toner is sieved with a powder tester (PT-E type manufactured by Hosokawa Micron Co., Ltd.) using a mesh having a mesh size of 45 μm and shaken for 2 minutes (vibration strength 3 V) and passed through the mesh. Means the percentage (%) of the used toner.

2. Method for Producing Alumina for External Addition of Toner (1) Method for Producing Alumina whose Main Crystal Phase is θ Phase or δ Phase Alumina whose main crystal phase is θ phase or δ phase is obtained by (1) aluminum alkoxide from aluminum and alcohol. S1, (2) Step S2 of hydrolyzing aluminum alkoxide to obtain aluminum hydroxide, (3) Step S3 of drying aluminum hydroxide to obtain aluminum hydroxide powder, (4) It can be manufactured by a step S4 of firing to obtain alumina.

(1.1) Step S1 of obtaining an aluminum alkoxide
In the step S1 of obtaining an aluminum alkoxide, as shown in the following equation (1), an aluminum alkoxide (Al (OR) ₃ ) is generated by a solid-liquid reaction between aluminum (Al) and an alcohol (ROH).
2Al + 6ROH → 2Al (OR) ₃ + 3H ₂ (1)

The purity of the aluminum is, for example, 99.9% by mass or more, preferably 99.99% by mass or more, and more preferably 99.999% by mass or more. That is, the content (total amount) of impurities such as iron, silicon, steel, and magnesium contained in aluminum is, for example, 1000 ppm or less, preferably 100 ppm or less, and more preferably 10 ppm or less.
The shape of the aluminum is not particularly limited, and may be any form such as an ingot, a pellet, a foil, a wire, and a powder.

  As the alcohol, a monohydric alcohol having 1 to 8 carbon atoms is preferable, and a monohydric alcohol having 1 to 4 carbon atoms is more preferable. As the carbon number decreases, the reactivity with aluminum increases. As the alcohol, specifically, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-pentyl alcohol, isopentyl alcohol, neopentyl Examples include alcohol, n-hexyl alcohol, isohexyl alcohol, neohexyl alcohol, n-heptyl alcohol, isoheptyl alcohol, neoheptyl alcohol, n-octyl alcohol, isooctyl alcohol, and neooctyl alcohol. The alcohols may be used alone or in combination of two or more.

  The reaction temperature of the aluminum and the alcohol is not particularly limited as long as the reaction proceeds, but from the viewpoint of promoting the reaction between the aluminum and the alcohol, the reaction is preferably performed under reflux conditions at the boiling point of the alcohol used. .

  As the aluminum alkoxide obtained in step S1, aluminum ethoxide, aluminum n-propoxide, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, aluminum t-butoxide, and the like are preferable.

  Note that the aluminum alkoxide may be partially chemically modified as long as the physical properties of the aluminum hydroxide generated in the next step S2 are not impaired. A mixture of a chemically modified aluminum alkoxide and an unmodified aluminum alkoxide may be used as a raw material aluminum alkoxide in the next step S2.

(1.2) Step S2 of obtaining aluminum hydroxide
In the step S2 of hydrolyzing the aluminum alkoxide to obtain aluminum hydroxide, the hydrolysis may be performed in one step or in two steps. In general, the hydrolysis rate of aluminum alkoxide is very high, and there is a possibility that fine aluminum hydroxides generated by local hydrolysis reaction may be strongly bonded to each other to form aggregates, whereas two-stage aluminum alkoxides may be aggregated. Aggregation can be suppressed by hydrolysis. Hereinafter, the two-stage hydrolysis will be described, but the two-stage hydrolysis method may be appropriately combined and performed in one stage.

  In the first hydrolysis (hereinafter sometimes referred to as “step S2-1”) of the two-stage hydrolysis, a part of the aluminum alkoxide is hydrolyzed using an alcohol containing a predetermined concentration of water. Separate the alcohol from the reaction mixture. By starting hydrolysis with a water-containing alcohol, local reactions can be suppressed and aggregation can be prevented.

  The water concentration in the water-containing alcohol is, for example, 5 to 30% by mass, preferably 5 to 20% by mass, and more preferably 5 to 10% by mass. By setting the concentration of water in the alcohol to 5% by mass or more, hydrolysis proceeds sufficiently. On the other hand, by setting the concentration to 30% by mass or less, local hydrolysis reaction is suppressed and aggregation of aluminum hydroxide is prevented. Can be prevented.

  In the step S2-1, it is preferable to add the water-containing alcohol such that the molar ratio of water in the water-containing alcohol to the aluminum alkoxide is, for example, 1.5 to 2.0. By setting the molar ratio in the above range, hydrolysis can be progressed as a whole while suppressing local excessive hydrolysis.

  The alcohol for preparing the water-containing alcohol is not particularly limited, but is preferably selected from the same range as the alcohol used in the step S1.

  The reaction temperature in step S2-1 is not particularly limited, and may be, for example, a temperature equal to or higher than normal temperature and equal to or lower than the boiling point of alcohol.

  After the completion of the first hydrolysis reaction, the alcohol is separated from the reaction mixture. The separation may be based on alcohol distillation or an ion exchange resin.

  Water is further added to the reaction mixture from which the alcohol has been separated, and a hydrolysis treatment is performed on the entire amount of the aluminum alkoxide (hereinafter, may be referred to as “Step S2-2”). In step S2-2, water is added and hydrolyzed so that the molar ratio of water to aluminum alkoxide is, for example, 1.0 to 7.0, and preferably 1.5 to 3.0. . By setting the molar ratio in the above range, hydrolysis can be progressed as a whole while suppressing local excessive hydrolysis.

  The reaction temperature in step S2-2 is not particularly limited, and may be, for example, a temperature equal to or higher than normal temperature and equal to or lower than the boiling point of water.

(1.3) Step S3 of obtaining aluminum hydroxide powder by drying
In step S3, the aluminum hydroxide obtained in step S2 is dried to obtain aluminum hydroxide powder. The aluminum hydroxide powder does not need to be completely dried, and may be properly dried so that it does not take too much time to obtain alumina by drying and firing the aluminum hydroxide powder.

  The drying method is not particularly limited, and a known method for evaporating water can be appropriately employed. The drying temperature is preferably higher than the boiling point of water or alcohol. As the drying method, for example, a material stationary type dryer, a material transfer type dryer, a material stirring type dryer, a hot air transfer type dryer, a cylindrical dryer, an infrared dryer, a freeze dryer, and a high frequency dryer can be used. .

(1.4) Step S4 of Baking to Obtain Alumina
The aluminum hydroxide powder produced in step S3 is pseudo-boehmite (γ-type aluminum oxyhydroxide). The pseudo-boehmite powder is calcined in step S4 to obtain alumina whose main crystal phase is a θ phase or a δ phase.

  The main crystal phase of alumina obtained differs depending on the firing temperature. The appropriate firing temperature needs to be adjusted according to the state of the aluminum powder, the heating rate, the firing time, the cooling rate, etc. As a guide, if the firing temperature is lower than 950 ° C., the main crystal phase becomes the γ phase. When the firing temperature is about 950 to 1050 ° C., the main crystal phase tends to be a δ phase. When the firing temperature is about 1050 to 1200 ° C., the main crystal phase tends to be the θ phase, and when the firing temperature exceeds 1200 ° C., the main crystal phase tends to be the α phase.

The heating rate of firing is not particularly limited, and is, for example, about 30 to 500 ° C./hour.
The firing time is, for example, about 1 hour to 20 hours.
The firing atmosphere is not particularly limited, and may be an air atmosphere, an inert atmosphere such as a nitrogen gas or an argon gas, or a reducing atmosphere.

  As a furnace to be used for firing, a material stationary firing furnace, for example, a tunnel kiln, a batch-type flow-flow box-type firing furnace, a batch-type parallel flow-type box-type firing furnace, or the like can be used. An electric furnace can also be used.

  There is no particular limitation on the firing vessel for accommodating the aluminum hydroxide powder, and for example, a square, bottomed circular, or polygonal column-shaped sheath can be used. The firing container is preferably made of alumina. By using an alumina firing container, contamination of alumina during firing can be prevented, and high-purity alumina can be obtained.

  Prior to the baking treatment, the aluminum hydroxide powder is granulated, the obtained granules are pre-dried, and the pre-dried granules are filled in a baking container made of alumina and calcined, whereby the alumina is You may get it. By filling the granulated material obtained by preliminarily drying the granulated material of the aluminum hydroxide powder into a firing vessel and firing, the loss due to scattering during firing can be reduced. In addition, by pre-drying the granulated product obtained by granulating the aluminum hydroxide powder, the work of filling the firing container can be efficiently performed.

(2) Method for producing alumina in which the main crystal phase is the κ phase Gibbsite powder (γ-type aluminum trihydroxide) is obtained by a known method such as the Bayer method, and the gibbsite powder is subjected to the same method as in step S4. By firing, alumina having a main crystal phase of a κ phase is obtained. However, even when gibbsite powder is used as a raw material, it is necessary to adjust the firing temperature. When the firing temperature is about 800 to 1000 ° C., the main crystal phase tends to be a κ phase, and when the firing temperature exceeds 1000 ° C., the main crystal phase becomes It is easy to become α phase.

(3) Formation of Surface Hydrophobized Layer The surface hydrophobized layer can be formed by mixing the alumina produced as described above and the above-mentioned silane compound. A mill mixer may be used for the mixing. By using a mill mixer, a surface hydrophobized layer can be formed more uniformly. In addition, since the alumina has a θ phase, a δ phase, or a κ phase as a main crystal phase, a decrease in the BET specific surface area is suppressed even when the alumina is surface-treated using a mill mixer.

3. Toner The alumina is used as an external additive of the toner. The content of the alumina in the toner is, for example, 0.1 to 5.0% by mass, preferably 0.2 to 2.0% by mass, and more preferably 0.5 to 1.5% by mass.
As an external additive of the toner, titanium oxide may be used together with alumina. The total content of alumina and titanium oxide in the toner is, for example, 0.1 to 5.0% by mass, preferably 0.2 to 2.0% by mass, and more preferably 0.5 to 1.5% by mass. . The proportion of alumina in the total content of alumina and titanium oxide is, for example, 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more.

  The toner includes, as a base material, binder resin particles containing a colorant. As the binder resin, various monomers are included alone or a copolymer of various monomers is included. Examples of the monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-ethylstyrene, vinyltoluene, 2,4-dimethylstyrene, and p-methylstyrene. Styrene monomers such as n-butylstyrene, p-phenylstyrene, p-chlorostyrene; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n (meth) acrylate -Butyl, isobutyl (meth) acrylate, n-octyl (meth) acrylate, dodecyl (meth) acrylate, hydroxyethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, phenyl (meth) acrylate, (Meth) acryl such as stearyl (meth) acrylate and 2-chloroethyl (meth) acrylate Ester monomers; carboxylic acid group-containing monomers such as (meth) acrylic acid, maleic acid, maleic anhydride, fumaric acid, phthalic acid, phthalic anhydride, and cinnamic acid; ethylene, propylene, butylene, isobutylene, etc. Olefins; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride; vinyl esters such as vinyl acetate and vinyl propylene acid; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; acrylonitrile and the like Nitriles; crosslinkable monomers such as divinylbenzene. The monomer may be modified with an alkylene glycol such as ethylene glycol or propylene glycol. As the copolymer, a styrene copolymer is preferable, and a styrene acrylic copolymer is more preferable.

  Colorants include carbon black, lamp black, magnetite, titanium black, chrome yellow, ultramarine, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine 6G, calco oil blue, quinacridone, benzidine yellow, rose bengal, malachite. Green lake, quinoline 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 184, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 180, C.I. I. Solvent Yellow 162, C.I. I. Pigment Blue 5: 1, C.I. I. Pigment Blue 15: 3 and the like. The colorants can be used alone or in a suitable mixture.

  Further, the toner may contain silica particles, a release agent, a charge control agent, and the like as external additives.

  The silica particles may be either hydrophobic silica particles or positively chargeable silica particles. In the hydrophobic silica particles, the surface of the silica particles has a silane compound such as hexamethyldisilazane or dimethyldichlorosilane; silicone such as dimethylsilicone, methylphenylsilicone, fluorine-modified silicone oil, alkyl-modified silicone oil, or epoxy-modified silicone oil. These are particles treated with an oil or the like by a wet method or a dry method. The positively chargeable silica particles are particles treated with an amino group-containing component such as an aminosilane coupling agent and an amino-modified silicone oil. The addition of the hydrophobic silica particles or the positively chargeable silica particles can improve the fluidity and chargeability of the toner.

  The silica particles are small particle size silica having a number average primary particle size of about 5 to 19 nm, medium particle size silica having a number average primary particle size of about 20 to 49 nm, and large particles having a number average primary particle size of about 50 to 250 nm. Diameter silica and the like are known and can be used in appropriate combination. It is preferable to use the small particle size silica and the large particle size silica in combination. The use of the large-particle-diameter silica provides a spacer effect, prevents the small-particle-diameter silica from being buried in the surface of the toner resin particles, and can efficiently increase the fluidity and chargeability of the toner.

  Examples of the release agent include paraffin wax, microwax, microcrystalline wax, cadelilla wax, carnauba wax, rice wax, montan wax, polyethylene wax, polypropylene wax, oxidized polyethylene wax, oxidized polypropylene wax, and the like. , Polyethylene wax, polypropylene wax, carnauba wax, ester wax and the like.

  The charge control agent is used to stabilize the chargeability of the toner, and is known to control the toner to be negatively chargeable and to control the toner to be positively chargeable. Examples of the device that controls the toner to have a negative charge include: an organometallic complex (monoazo metal complex; acetylacetone metal complex); a metal complex or a metal salt of an aromatic hydroxycarboxylic acid or an aromatic dicarboxylic acid; an aromatic monocarboxylic acid, an aromatic Examples include polycarboxylic acids and their metal salts and anhydrides; esters and phenol derivatives such as bisphenol, and metal complexes or metal salts of aromatic hydroxycarboxylic acids are preferred.

  Examples of the toner that controls the toner to have a positive charge include denatured products of nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate; phosphonium Salts and other onium salts and their lake pigments; triphenylmethane dyes and these lake pigments (as the lacking agent, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricia, Acid, ferrocyanide compound and the like); metal salts of higher fatty acids and the like, and nigrosine compounds, quaternary ammonium salts and the like are preferable.

  Hereinafter, the present invention will be described more specifically with reference to Examples. However, the present invention is not limited to the following Examples, and may be appropriately modified within a range that can conform to the purpose of the preceding and the following. It is, of course, possible to implement them, and all of them are included in the technical scope of the present invention.

The physical properties of the powders obtained in the examples and comparative examples were determined as follows.
1. BET Specific Surface Area Using "Flowsorb III 2310" manufactured by Shimadzu Corporation, the BET specific surface area was determined by the nitrogen adsorption single point method according to the method specified in JIS-Z8830 (2013). Each measurement condition was as follows.
Carrier gas: Nitrogen / helium mixed gas Filled sample amount: 0.1 g
Sample pretreatment conditions: treatment at 200 ° C for 20 minutes Nitrogen adsorption temperature: liquid nitrogen temperature (-196 ° C or less)
Nitrogen desorption temperature: room temperature (about 20 ° C)

2. Pore volume and pore radius by nitrogen adsorption method Using "BELPREP-vac II" manufactured by Microtrac Bell Co., Ltd., the powder to be evaluated was subjected to vacuum deaeration at 120 ° C for 8 hours. Next, using manufactured Microtrac Bell Inc. The "BELSORP-mini", with constant volume method to measure the adsorption and desorption isotherm by N ₂ under the following conditions.
Adsorption temperature: 77K
Adsorbate: N ₂
Saturated vapor pressure: Actual measurement Adsorbate cross section: 0.162 nm ²
Equilibrium waiting time: 500 seconds From the obtained desorption isotherm, the average pore radius and the pore volume of mesopores (pore radius 1.3 nm to 100 nm) were calculated by the BJH method.

3. Average particle size (D50)
The particle size distribution was measured by a laser diffraction method using a laser particle size distribution measuring device (“Microtrack MT3300EXII” manufactured by Microtrac Bell Co., Ltd.), and the particle diameter D50 corresponding to a cumulative percentage of 50% on a volume basis was defined as the average particle diameter. did. At the time of measurement, dispersion was performed for 5 minutes in a 0.2% by mass aqueous sodium hexametaphosphate solution using ultrasonic waves with a built-in device of 40 W, and the refractive index of alumina was set to 1.76.

4. Light bulk density and heavy bulk density Light bulk density and heavy bulk density of the powder to be evaluated were determined in accordance with JIS R9301 (1999).

5. Moisture content About 10 g of the powder to be evaluated was weighed and heated at a temperature of 120 ° C. for 45 minutes to evaporate the moisture. The weight of the powder after heating was measured, and the moisture content was calculated based on the following equation.
Moisture percentage (%) = (weight of powder before heating (g) −weight of powder after heating (g)) / weight of powder before heating (g) × 100

6. Determination of main crystal phase, α-phase contamination rate As an X-ray diffractometer, a Rigaku Corporation “RAD-RB RU-200 type” was used to measure the CuKα characteristic X-ray diffraction pattern of the powder to be evaluated. Associated peaks (α phase: 2θ = 57.5 °, θ phase: 2θ = 32.7 °, δ phase: 2θ = 36.5 °, γ phase: 2θ = 45.4 °, κ phase: 2θ = 42 .9 °), and the peak having the highest intensity was determined as the main crystal phase (Examples 1 to 3 were the θ phase as the main crystal phase, and Comparative Examples 1 to 3 were the γ phase as the main crystal phase. there were).
The intensity of the α phase peak (θ = 57.5 °) and the peak of the main crystal phase (32.7 ° when the main crystal phase is the θ phase; 45.5 ° when the main crystal phase is the γ phase) The strength was obtained, and the α-phase mixing ratio was calculated by the following equation.
α phase contamination rate (%) = (α phase peak intensity / main crystal phase peak intensity) × 100

7. BET specific surface area of the evaluated powders before BET reduction rate surface treatment (B1: m ² / g) and BET specific surface area of the evaluated powders after surface treatment: BET accordance Because (B2 m ² / g) and the following formula The rate of decline was determined.
BET reduction rate (%) = (B1−B2) / B1 × 100

8. Hydrophobicity 50 g of distilled water was put into a beaker, and then 0.2 g of a powder to be evaluated was gently added. While stirring the mixture with a magnet stirrer, methanol was added dropwise little by little, and the time when the whole of the powder to be evaluated floating on the water surface sank into the solution was defined as the end point. The degree of hydrophobicity was determined by the following equation, where W (g) was the methanol titer required until the end point.
Hydrophobicity (%) = {W / (50 + W)} × 100

9. Flowability 0.1 g of powder to be evaluated and 10 g of spherical particles of cross-linked polymethyl methacrylate (particle size: 8 μm, product name: SSX-108, manufactured by Sekisui Plastics Co., Ltd.) are mixed with a mixer (model A10, manufactured by IKA). The mixture was stirred and mixed for 1 minute to obtain an externally added composition. Using a powder tester (PT-E type manufactured by Hosokawa Micron Corporation), the external additive composition is sieved by vibrating for 2 minutes using a mesh having a mesh size of 45 μm (vibration strength: 3 V). (%). The larger the value of the obtained fluidity, the better the fluidity.

Example 1
Aluminum powder having a purity of 99.99% and isopropyl alcohol were subjected to a solid-liquid reaction under reflux conditions to prepare aluminum isopropoxide. An alcohol aqueous solution of 15.0 parts by weight of water and 165.7 parts by weight of isopropyl alcohol was added to a mixed solution of 100.0 parts by weight of the obtained aluminum isopropoxide and 11.1 parts by weight of isopropyl alcohol to hydrolyze. . Next, 99.3 parts by weight of isopropyl alcohol is separated and recovered by distillation, and then 24.9 parts by weight of water and an aqueous alcohol solution of 64.2 parts by weight of isopropyl alcohol are added to carry out hydrolysis to obtain slurry aluminum hydroxide. I got The aluminum hydroxide slurry was dried to obtain a dry powdery aluminum hydroxide having a light bulk density of 0.1 g / cm ³ .
The dried powdered aluminum hydroxide is baked in an electric furnace at a temperature of 1100 ° C. for 4 hours in an air atmosphere to obtain an alumina powder having a θ-phase main crystal phase (hereinafter referred to as θ-alumina powder). Was.
5.5 kg of alumina balls having a diameter of 15 mm and a predetermined amount of isobutyltrimethoxysilane (trade name “OFS-”) as a silane coupling agent were placed in a grinding pot of a small vibration mill device (model YAMP-6JN, Murakami Seiki Seisakusho). 2306 "(manufactured by Dow Corning Toray Co., Ltd., with a minimum coating area of 439 m ² / g), and vibrated for 1 minute to adhere isobutyltrimethoxysilane to the entire alumina ball. To the pulverizing pot, 100 g of the above-obtained θ-alumina powder was added as an object to be treated, and the surface treatment of the θ-alumina powder was performed by applying vibration for 24 minutes. The surface-treated alumina powder was taken out of the pot and sieved with a 210 μm mesh.
The used amount (addition amount) of isobutyltrimethoxysilane is a value obtained by substituting 50 (%) for the coverage in the following equation.

なお、前記シランカップリング剤の最小被覆面積（ｍ²／ｇ）は、（６．０２×１０²³×１３×１０^-20）／（シランカップリング剤の分子量）により求まる値である。

The minimum coverage area (m ² / g) of the silane coupling agent is a value determined by (6.02 × 10 ²³ × 13 × 10 ^-20 ) / (molecular weight of the silane coupling agent).

Example 2
The silane coupling agent was changed from isobutyltrimethoxysilane to n-hexyltrimethoxysilane (trade name “Z-6583”, manufactured by Toray Dow Corning Co., Ltd., minimum covering area: 379 m ² / g) (the covering rate was kept at 50%) Alumina powder (surface-treated product, sieved product) was obtained in the same manner as in Example 1 except for (1).

Example 3
The silane coupling agent was changed from isobutyltrimethoxysilane to n-decyltrimethoxysilane (trade name “Z-6210” manufactured by Toray Dow Corning Co., Ltd., minimum coverage area 298 m ² / g) (the coverage rate was kept at 50%). Alumina powder (surface-treated product, sieved product) was obtained in the same manner as in Example 1 except for (1).

Comparative Example 1
The same procedure as in Example 1 was carried out except that the firing temperature of the dried powdery aluminum hydroxide was changed to 900 ° C., and the holding time at the firing temperature was changed to 4 hours. Hereinafter, referred to as γ-alumina powder). The obtained γ-alumina powder was subjected to a surface treatment in the same manner as in Example 1 and sieved.

Comparative Example 2
Surface treatment was performed in the same manner as in Example 2 using the γ-alumina powder obtained in the same manner as in Comparative Example 1, and sieved.

Comparative Example 3
Surface treatment was carried out in the same manner as in Example 3 using γ-alumina powder obtained in the same manner as in Comparative Example 1, and sieved.
Table 1 shows the evaluation results of the powders obtained in Examples 1 to 3 and Comparative Examples 1 to 3.

Claims (6)

  Alumina for toner external addition in which the main crystal phase is a θ phase, a δ phase, or a κ phase.   2. The alumina for external addition to a toner according to claim 1, wherein the pore volume of the mesopores having a pore radius of 1.3 nm to 100 nm is 1.5 mL / g or less.   The alumina for external addition to a toner according to claim 1 or 2, having a hydrophobic layer on the surface. Toner external添用alumina according to claim 3 BET specific surface area of 40 m ² / g or more.   The alumina for external addition to a toner according to claim 3 or 4, wherein the water content is 5.0% or less. The alumina for external addition to a toner according to any one of claims 3 to 5, wherein the hydrophobic layer is an alkoxysilane hydrophobic layer.