JP4624310B2 - Toner for electrophotography - Google Patents

Description

  The present invention relates to an electrophotographic toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, and a two-component developer containing the toner.

  In high-speed printing, the external additive is likely to be embedded, and when the external additive is embedded, the charge amount is reduced, or the adhesion to the photoconductor is increased with a decrease in the spacer effect, resulting in poor transferability.

  Therefore, in order to prevent embedding of the external additive, a toner containing an external additive having a large particle size has been proposed (see Patent Document 1). However, an external additive having a large particle size has a drawback that embedding is reduced, but has a defect that it is easily detached, and a stable image may not be provided in continuous printing.

In contrast, by treating the surface of a large particle size inorganic fine particle having an average primary particle size of 100 to 500 nm with a surface treatment agent having a cationic group, the negative particle surface is charged with a polarity opposite to that of the negatively charged toner surface. Studies have been made to avoid detachment of inorganic fine particles having a diameter (see Patent Document 2). However, the surface treatment with an external additive having a reverse polarity tends to cause aggregation because charges are biased on the surface of the external additive.
JP-A-6-332235 JP-A-11-1184139

  An object of the present invention relates to an electrophotographic toner capable of obtaining stable chargeability and transferability even in high-speed continuous printing and reducing image unevenness and image density reduction, and a two-component developer containing the toner.

The present invention
[1] An electrophotographic toner comprising toner base particles containing a binder resin, a charge control agent and a colorant and an external additive, wherein the external additive is an interlayer of a clay mineral having a layered structure The present invention also relates to an electrophotographic toner comprising an intercalation compound in which an ionic organic component is intercalated, and [2] a two-component developer comprising the electrophotographic toner according to (1) and a carrier.

  The toner for electrophotography of the present invention and the two-component developer containing the toner can maintain stable chargeability and transferability even in high-speed continuous printing, and image unevenness and reduction in image density are reduced. It has an excellent effect.

  The present invention relates to an electrophotographic toner comprising toner base particles containing a binder resin, a charge control agent and a colorant and an external additive, wherein an ionic organic layer is used as an external additive between layers of a clay mineral having a layered structure. It has a great feature in that the component contains an intercalated intercalation compound, which prevents the charge from being biased on the surface of the external additive and intercalates an ionic organic component having a polarity opposite to that of the toner. However, since the aggregation of the external additive does not occur on the toner, uniform chargeability can be imparted to the toner. Further, by intercalating an ionic organic component having a polarity opposite to that of the toner, particles having a large particle diameter are not easily detached from the toner by electrostatic attraction, and a higher spacer effect can be exhibited. As a result, stable transferability can be maintained, and image unevenness and image density reduction are reduced.

  Examples of the clay mineral having a layered structure in the present invention include silicate-based, oxide-based, metal phosphocargon-based, and zirconium phosphate-based clay minerals. Among these, silicate-based clay minerals are used. preferable.

As a silicate clay mineral, the formula (A):
(X, Y) _2-3 Z ₄ O ₁₀ (OH) ₂ .mH ₂ O. (W _n ) (A)
(Wherein X is Al, Fe (III), Mn (III) or Cr (III), Y is Mg, Fe (II), Mn (II), Ni, Zn or Li, Z is Si or Al, W Is preferably a clay mineral represented by K, Na or Ca, n is a number from 0 to 1, preferably 1/3, and H ₂ O is interlayer water, and has a 2: 1 type layered structure. Hydrous aluminum silicate clay minerals are more preferred. Examples of the clay mineral represented by the formula (A) include natural clay minerals such as montmorillonite, sabonite, hectorite, vermiculite and beidellite. In the present invention, this montmorillonite is used from the viewpoint of obtaining good chargeability. Bentonite as the main component is preferred. Further, in the present invention, synthetic clay minerals having the same structure as these may be used, and those in which the (OH) ₂ moiety in the formula (A) is substituted with a halogen atom such as F, tetrasilicon mica, Synthetic mica such as Deniolite may be used.

  The average particle size of the clay mineral is preferably from 0.1 to 2 μm, more preferably from 0.2 to 1 μm, from the viewpoint of preventing embedding and liberation and from the viewpoint of setting the charge amount to an appropriate level. Note that there is no substantial change in the particle size of the clay mineral before and after intercalation. Therefore, like the clay mineral, the average particle size of the intercalation compound is preferably 0.1 to 2 μm, more preferably 0.2 to 1 μm, from the viewpoint of preventing desorption and making the charge amount an appropriate level. The average particle diameter of the external additive in the present specification including the intercalation compound means the average particle diameter of the primary particles, and is measured by the method described in Examples described later.

  Examples of the ionic organic component in the present invention include quaternary ammonium salts and amine salts. Among these, quaternary ammonium salts are preferable from the viewpoint of obtaining good chargeability.

As the quaternary ammonium salt, the formula (I):

(In the formula, R ^{1 to} R ⁴ may be the same or different, and an alkyl group having 1 to 30 carbon atoms, an alkylphenyl group having 7 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms, X ⁻ is An anion is shown, and R ^{1 to} R ⁴ may have a substituent such as a hydroxyl group or a halogen atom, but are preferably unsubstituted.

In the present invention, at least one of R ^{1 to} R ⁴ , preferably 2 is an alkyl group having 10 to 20 carbon atoms, and the remaining groups are further selected from the viewpoint that the charging characteristics can be further stabilized. More preferably, it is an alkyl group having 1 to 3 carbon atoms, preferably an alkyl group having 1 carbon atom (methyl group). X ⁻ includes halogen ions such as chlorine ion and bromine ion, aromatic sulfonate ions such as toluene sulfonate ion and hydroxy naphthalene sulfonate ion, aromatic carboxylate ion, molybdate ion, tungstate ion and hydroxy ion. The anion is preferably a halogen ion, a halogen aromatic sulfonate ion, an aromatic carboxylate ion and a molybdate ion, more preferably a halogen ion. Examples of commercially available products containing the compound represented by the formula (I) include “Coutamin 24P” (manufactured by Kao Corporation), Kotamin 86P Conch (manufactured by Kao Corporation), Cotamin D86P (manufactured by Kao Corporation), and the like.

  The intercalation compound in the present invention is, for example, a mixture of a clay mineral diluted to an appropriate concentration with water or the like and an ionic organic component adjusted to an appropriate viscosity by dilution with water or heating. It is obtained by stirring or kneading.

  Intercalation of ionic organic components results in exchange of cations between the clay mineral layers and cations in the ionic organic components. Intercalation refers to the infiltration of molecules, ions, etc. into the interlayer region of clay minerals by contact with alkali metal ions or alkaline earth metal ions, etc. on the surface and layer of clay. This refers to causing an ion exchange reaction. The chargeability of the intercalation compound can be adjusted by the type of ionic organic component used for intercalation and the amount of ionic organic component.

  More specific methods include, for example, a method in which an ionic organic component is added and reacted with a clay mineral suspension in which clay mineral is dispersed in water. The solid (clay mineral) dispersion concentration in the suspension is not particularly limited as long as the clay mineral can be dispersed, but is preferably about 1 to 5% by weight. At this time, a clay mineral freeze-dried in advance may be used.

  The mixing ratio of the clay mineral and the ionic organic component (clay mineral / ionic organic component) is preferably 50/50 to 90/10, more preferably 60/40 to 80/20 in terms of solid content.

  Stirring of the clay mineral and the ionic organic component can be performed by a usual method using a disper or the like.

  The reaction temperature between the clay mineral and the ionic organic component is preferably below the decomposition point of the ionic organic component.

  After the reaction, the solid-liquid is separated, and the produced intercalation compound is washed with water or hot water to remove the by-produced electrolyte, then dried, and pulverized as necessary to obtain the intercalation compound.

  The generation of intercalation compounds is a method utilizing chemical analysis, X-ray diffraction, NMR, infrared absorption spectrum, thermobalance, differential thermal analysis, rheology of highly polar solvent systems, swelling power in high polar organic solvents, color tone, etc. It can be confirmed by selecting according to the purpose and combining them appropriately.

For example, in the method using X-ray diffraction, the formation of an intercalation compound can be easily confirmed by measuring the magnitude of 001 bottom reflection. The raw clay mineral is 10Å in the dehydrated state and has a bottom spacing of 12 to 16Å under normal temperature and humidity, but the intercalation compound in the present invention has a bottom spacing of about 18Å.

  The content of the intercalation compound is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, and still more preferably 0.1 to 1 part by weight with respect to 100 parts by weight of the toner base particles.

  The content of the intercalation compound in the external additive is preferably 10 to 50% by weight, more preferably 20 to 30% by weight, from the viewpoint of desorption prevention and environmental stability. Examples of the external additive other than the interlayer compound include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide. Among these, silica having a low specific gravity is preferable from the viewpoint of preventing embedding.

From the viewpoint of environmental stability, the silica is preferably hydrophobic silica that has been subjected to a hydrophobic treatment. The hydrophobizing method is not particularly limited, and examples of the hydrophobizing agent include hexamethyldisilazane (HMDS), dimethyldichlorosilane, silicone oil, methyltriethoxysilane, and the like. Among these, hexamethyldisilazane is included. Is preferred. The treatment amount of the hydrophobizing agent is preferably 1 to 7 mg / m ² per surface area of the inorganic fine particles.

  The average particle size of the inorganic fine particles is preferably from 3 to 300 nm, more preferably from 5 to 100 nm, from the viewpoint of chargeability and prevention of scratches on the photoreceptor.

  The content of the inorganic fine particles is preferably 0.01 to 10 parts by weight and more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner base particles.

  In the present invention, the toner base particles contain at least a binder resin, a charge control agent, and a colorant.

  Examples of the binder resin in the present invention include vinyl resins such as polyester and styrene-acrylic resins, epoxy resins, polycarbonates, polyurethanes, hybrid resins having two or more resin components, and the like. When the toner has a carboxyl group as a charge control agent, polyester is preferable. The synergistic action of the carboxyl group of the polyester and the carboxyl group of the charge control agent further makes the charge on the toner surface more uniform, so that the effect of the present invention can be exhibited more remarkably. The polyester content is preferably 50 to 100% by weight in the binder resin, more preferably 70 to 100% by weight, and still more preferably 100% by weight.

  The polyester is obtained by polycondensing a known alcohol component and a known carboxylic acid component such as a carboxylic acid, a carboxylic acid anhydride, or a carboxylic acid ester as raw material monomers.

  Examples of the alcohol component include alkylenes of bisphenol A such as polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane. (Carbon number 2 to 3) Oxide (average added mole number 1 to 16) adduct, ethylene glycol, propylene glycol, glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol A, sorbitol, or alkylene thereof (carbon number 2 -4) Oxide (average added mole number 1-16) adduct and the like.

  The carboxylic acid component includes dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid, adipic acid and succinic acid, alkyl groups having 1 to 20 carbon atoms such as dodecenyl succinic acid and octenyl succinic acid, or carbon. Trivalent or higher polyvalent carboxylic acids such as succinic acid, trimellitic acid and pyromellitic acid substituted with alkenyl groups having 2 to 20 carbon atoms, anhydrides of these acids and alkyls of these acids (1 to 3 carbon atoms) ) Esters and the like. The acids as described above, and anhydrides and alkyl esters of these acids are collectively referred to herein as carboxylic acid compounds.

  The polyester is obtained, for example, by subjecting an alcohol component and a carboxylic acid component to condensation polymerization at a temperature of 180 to 250 ° C. in an inert gas atmosphere, if necessary, in the presence of an esterification catalyst.

  From the viewpoint of durability and fixability, the softening point of the polyester is preferably 80 to 165 ° C, the glass transition point is preferably 50 to 85 ° C, and the acid value is preferably 0.5 to 60 mgKOH / g.

  As the colorant, dyes and pigments used as toner colorants can be used. Carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, solvent red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Disazo Yellow, etc., and these can be used alone or in admixture of two or more. The toner of the present invention is a black toner or a color toner. Either may be sufficient. The content of the colorant is preferably 1 to 40 parts by weight and more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  The charge control agent may be either a positively chargeable charge control agent or a negatively chargeable charge control agent, and these may be used in combination.

  Examples of the positively chargeable charge control agent include nigrosine dyes, quaternary ammonium salts, and the like, but quaternary ammonium salts are preferable from the viewpoint of little influence on the color tone of the toner.

  As quaternary ammonium salts of carboxylic acids, the formula (II):

(In the formula, R ^{5 to} R ⁸ may be the same or different, and may be substituted with a halogen atom, a lower alkyl group having 1 to 8 carbon atoms, an alkyl group or alkenyl group having 8 to 22 carbon atoms, or aryl group or aralkyl group having 6 to 20 carbon atoms, Y ^- represents a carboxylate ion)
The compound represented by these is preferable.

In the present invention, R ^{5 to} R ⁸ are each a lower alkyl group having 1 to 4 carbon atoms which may be substituted with a halogen atom, carbon number, since the charging characteristics are more stable and the fixability can be improved. 12-18 alkyl groups, phenyl groups and benzyl groups are preferred, and Y ⁻ is preferably an aromatic carboxylate ion or an aliphatic carboxylate ion, more preferably an aromatic carboxylate ion. Examples of the aromatic carboxylate ion include a carboxylate ion having a benzoic acid structure.

  Examples of the carboxylic acid having a benzoic acid structure include benzoic acid and dithiodibenzoic acid.

  Furthermore, as a more preferred quaternary ammonium salt of dithiodibenzoic acid, in the present invention, a compound of formula (IIa):

The compound represented by these is mentioned.

  As a commercial product containing the compound represented by the formula (IIa), “COPY CHARGE PSY” (manufactured by Clariant) and the like can be mentioned.

  Examples of the negatively chargeable charge control agent include metal-containing azo dyes, copper phthalocyanine dyes, metal complexes of salicylic acid compounds, nitroimidazole derivatives, and the like. Metal complexes are preferred.

  As a metal complex of a salicylic acid compound, the formula (III):

Wherein R ⁹ , R ¹⁰ and R ¹¹ are each independently a hydrogen atom, a linear or branched alkyl group or alkenyl group having 1 to 10 carbon atoms, M is zinc, zirconium, chromium, aluminum, Copper, nickel or cobalt, m is an integer of 2 or more, and n is an integer of 1 or more)
The metal complex of the salicylic acid compound represented by these is preferable.

In the formula (III), R ¹⁰ is preferably a hydrogen atom, and R ⁹ and R ¹¹ are preferably a branched alkyl group, more preferably a tert-butyl group.

  As M, zinc and chromium having high electronegativity and good charging effect are preferable, and chromium is more preferable.

Examples of commercially available chromium complexes of salicylic acid compounds in which R ¹⁰ is a hydrogen atom and R ⁹ and R ¹¹ are tert-butyl groups preferably used in the present invention include “Bontron E-81” (Orient Chemical Industries, Ltd.). As a commercial product of a zinc complex of a salicylic acid compound in which R ¹⁰ is a hydrogen atom and R ⁹ and R ¹¹ are tert-butyl groups, “Bontron E-84” (manufactured by Orient Chemical Co., Ltd.), etc. Is mentioned.

  The content of the charge control agent varies depending on the type and the like, but is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. For example, in the case of a quaternary ammonium salt, 0.1 to 5 parts by weight is preferable with respect to 100 parts by weight of the binder resin, and 0.3 to 3 parts by weight is more preferable. In the case of a metal complex of a salicylic acid compound, the content thereof is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 7 parts by weight with respect to 100 parts by weight of the binder resin. When a quaternary ammonium salt and a metal complex of a salicylic acid compound are used in combination, from the viewpoint of imparting proper chargeability to the toner base particles, when imparting positive chargeability to the toner base particles, a quaternary ammonium salt and The weight ratio of the metal complex of the salicylic acid compound (metal complex of the salicylic acid compound / quaternary ammonium salt) is preferably 1/10 to 1/3, and more preferably 1/8 to 1/5. From the same viewpoint, when the toner base particles are provided with negative chargeability, the weight ratio of the metal complex of the quaternary ammonium salt to the salicylic acid compound (quaternary ammonium salt / metal complex of the salicylic acid compound) is 1 / 8 to 1/2 is preferable, and 1/5 to 1/3 is more preferable.

  Furthermore, additives such as release agents, conductivity modifiers, extender pigments, reinforcing fillers such as fibrous substances, antioxidants, anti-aging agents, and magnetic materials are added as appropriate to the toner of the present invention. May be.

  The toner of the present invention is obtained through a step of surface-treating toner base particles containing a binder resin, a charge control agent and a colorant and, if necessary, various additives with an external additive. The toner base particles are preferably pulverized toner. For example, a binder resin, a colorant, and the like are mixed with a mixer such as a Henschel mixer or a ball mill, and then melt-kneaded with a hermetic kneader or a uniaxial or biaxial extruder. After cooling, coarsely pulverized using a hammer mill or the like, further pulverized by a fine pulverizer or mechanical pulverizer using a jet stream, and predetermined by a classifier using a swirling airflow or a classifier using the Coanda effect It is obtained by classifying to a particle size of

  The surface treatment step of the toner base particles with the external additive is preferably a dry mixing method in which the external additive and the toner base particles are mixed using a high-speed stirrer such as a Henschel mixer or a super mixer, a V-type blender or the like. The external additives may be mixed in advance and added to a high-speed stirrer or a V-type blender, or may be added separately.

The volume median particle size (D ₅₀ ) of the toner of the present invention is preferably 3 to 15 μm, preferably 4 to 15 μm, before adding an external additive such as an interlayer compound, from the viewpoint of ease of handling as a powder. 9 μm is more preferable. In the present specification, the volume-median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size.

  The electrophotographic toner of the present invention can be used as either a one-component developing method or a two-component developing method as it is as a one-component developing toner or as a two-component developing toner used by mixing with a carrier. The toner of the present invention can be suitably used as a toner for two-component development because printing stability is good and speed can be increased. Accordingly, the present invention further provides a two-component developer containing the toner of the present invention and a carrier.

In the present invention, from the viewpoint of image characteristics, it is preferable to use a carrier with low saturation magnetization that weakens the area around the magnetic brush. Saturation magnetization of the carrier is preferably ^{40~100Am 2 / kg, 50~90Am 2 /} kg is more preferable. The saturation magnetization is preferably 100 Am ² / kg or less from the viewpoint of adjusting the hardness of the magnetic brush and maintaining gradation reproducibility, and preferably 40 Am ² / kg or more from the viewpoint of preventing carrier adhesion and toner scattering. The saturation magnetization of the carrier is measured by the method described in Examples described later.

  As the core material of the carrier, those made of known materials can be used without particular limitation, for example, ferromagnetic metals such as iron, cobalt, nickel, magnetite, hematite, ferrite, copper-zinc-magnesium ferrite, Examples include alloys and compounds such as manganese ferrite and magnesium ferrite, and glass beads. Among these, iron powder, magnetite, ferrite, copper-zinc-magnesium ferrite, manganese ferrite, and magnesium ferrite are preferable from the viewpoint of chargeability. From the viewpoint of image quality, ferrite, copper-zinc-magnesium ferrite, manganese ferrite and magnesium ferrite are more preferable.

  The surface of the carrier is preferably coated with a resin from the viewpoint of reducing carrier contamination. The resin that coats the carrier surface varies depending on the toner material. For example, fluororesin such as polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin such as polydimethylsiloxane, polyester, styrenic resin, Acrylic resins, polyamides, polyvinyl butyral, amino acrylate resins, and the like can be used, and these can be used alone or in combination of two or more. However, if the toner is negatively charged, the chargeability and surface From the viewpoint of energy, a silicone resin is preferable. The method for coating the core material with the resin is not particularly limited, for example, a method in which a coating material such as a resin is dissolved or suspended in a solvent and applied to the core material, or a method of simply mixing with a powder.

  In the two-component developer of the present invention obtained by mixing the toner and the carrier, the toner to carrier weight ratio (toner / carrier) is preferably 1/99 to 10/90, and 5/95 to 7/93. More preferred.

  The toner and the two-component developer of the present invention are subject to great stress on the toner and are likely to cause embedding and release of external additives. The linear velocity is preferably 400 mm / sec or more, more preferably 800 to 2500 mm / sec. Even in continuous printing using an image forming apparatus, embedding and release of external additives can be prevented, and good chargeability and transferability can be maintained. Here, the linear speed refers to the process speed of the image forming apparatus, and is determined by the paper feed speed of the fixing unit.

[Softening point of resin]
Using a flow tester (Shimadzu Corporation, CFT-500D), a 1 g sample was heated at a heating rate of 6 ° C / min, and a load of 1.96 MPa was applied by a plunger and extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. . The amount of plunger drop of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

[Glass transition point of resin]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the temperature was raised to 200 ° C, and the sample was cooled to 0 ° C at a temperature drop rate of 10 ° C / min. The temperature at the intersection of the extended line of the baseline below the maximum peak temperature of endotherm and the tangent line indicating the maximum slope from the peak rising portion to the peak apex.

[Acid value of the resin]
Measured according to the method of JIS K0070. However, only the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K0070 to the mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Volume-median particle diameter of toner (D ₅₀ )]
Measuring machine: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 100μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter)
Electrolyte: Isoton II (Beckman Coulter, Inc.)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) is dissolved in the electrolytic solution to a concentration of 5% by weight to obtain a dispersion.
Dispersion conditions: 10 mg of a measurement sample is added to 5 ml of the dispersion, and dispersed for 1 minute with an ultrasonic disperser, then 25 ml of an electrolyte is added, and further dispersed for 1 minute with an ultrasonic disperser. Prepare a dispersion.
Measurement conditions: After adjusting the particle size of 30,000 particles to a concentration that can be measured in 20 seconds by adding the sample dispersion to 100 ml of the electrolyte solution, 30,000 particles are measured, Determine the volume median particle size (D ₅₀ ).

[Average particle size of primary particles of external additive]
Obtained from the following formula.
Average particle diameter (μm) = 6 / (ρ × specific surface area (m ² / g))
In the formula, ρ is the specific gravity of the external additive, the specific gravity of bentonite and an intercalation compound in which an ionic organic component is intercalated into bentonite is 2.5, and the specific gravity of silica is 2.2. The specific surface area is a BET specific surface area determined by a nitrogen adsorption method. In the case of a hydrophobized external additive, the specific surface area of the raw material before the hydrophobizing treatment is used.
The above formula is assumed to be a sphere having a particle diameter R,
Specific surface area = S x (1 / m)
m (weight of particle) = 4/3 x π x (R / 2) ³ x specific gravity
S (surface area) = 4π (R / 2) ²
Is an expression obtained from

[Carrier saturation magnetization]
(1) Fill a plastic case with a lid of 7 mm outer diameter (6 mm inner diameter) and 5 mm height while tapping the carrier, and calculate the mass of the carrier from the difference between the weight of the plastic case and the weight of the plastic case filled with the carrier. .
(2) Set the plastic case filled with carrier in the sample holder of the magnetic property measuring device “BHV-50H” (VSMAGNETOMETER) of RIKEN ELECTRONICS CO., LTD., While vibrating the plastic case using the vibration function, Saturation magnetization is measured by applying a magnetic field of 79.6 kA / m. The obtained value is converted into saturation magnetization per unit mass in consideration of the mass of the filled carrier.

Resin production example 1
1,040 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 10 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 199 g of terephthalic acid and dibutyltin oxide Put 4g into a 5-liter four-necked flask equipped with a nitrogen inlet tube, dehydration tube, stirrer, and thermocouple, react at 230 ° C under normal pressure for 5 hours, and then react at 8.3kPa for 2 hours. I let you. The reaction solution is cooled to 210 ° C., 209 g of fumaric acid and 1 g of hydroquinone are added, reacted for 5 hours, and further reacted at 8.3 kPa until a predetermined softening point is reached to obtain resin A (polyester). It was. The obtained resin A had a softening point of 109.5 ° C., a glass transition point of 64.4 ° C., and an acid value of 21.3 mgKOH / g.

Production Example 1 of Intercalation Compound
A solution in which 150 g of bentonite was dispersed in 5000 g of water and a solution in which 80 g of distearyldimethylammonium chloride was dissolved in 5000 g of water were mixed and reacted at room temperature for 2 hours with stirring. Next, the precipitate was taken out by filtration, washed and dried to obtain an intercalation compound A having an average primary particle size of 300 nm in terms of BET.

  When the obtained intercalation compound A was measured by X-ray diffraction, the bottom face distance calculated from its 001 reflection was 18.0 mm.

Examples 1-2 and Comparative Examples 1-4
Resin A 100 parts by weight, quinacridone pigment “Fastogen Super Magenta R” (Dainippon Ink and Chemicals) 5 parts by weight, salicylic acid compound chromium complex “Bontron E-81” (Orient Chemicals) 3.5 parts by weight, and 1 part by weight of quaternary ammonium salt of carboxylic acid “COPY CHARGE PSY” (manufactured by Clariant) and 1 part by weight of polypropylene wax “NP-105” (manufactured by Mitsui Chemicals) are mixed with a Henschel mixer and then mixed with a twin screw extruder. After melt-kneading and cooling, it was coarsely pulverized to about 1 mm using a hammer mill. The resulting coarsely pulverized product was finely pulverized by an air jet pulverizer and classified to obtain toner mother particles having a volume-median particle size (D ₅₀ ) of 8.5 μm.

  The toner base particles obtained and 0.9 parts by weight of hydrophobic silica “R972” (manufactured by Nippon Aerosil Co., Ltd.) hydrophobized with dimethyldichlorosilane were mixed for 3 minutes with a Henschel mixer. A toner subjected to external addition treatment was obtained.

6 parts by weight of the obtained toner and 94 parts by weight of ferrite carrier (average particle diameter: 60 μm, saturation magnetization: 68 Am ² / kg) were mixed to obtain a two-component developer.

Test example 1
A two-component developer is mounted on a non-magnetic two-component development type image forming apparatus "Vario stream 9000" (Oce Printing Systems), and after adjusting the toner concentration to 6%, the printing rate is 9% and the linear speed is 1000mm. 30,000 copies were printed at / sec. Solid images were printed at the time of printing 1000 sheets (initial printing) and at the time of printing 30,000 sheets (after printing), and the image density and image unevenness were evaluated by the following methods. The results are shown in Table 1.

[Image density]
The image density of the printed part was measured at 5 points with a color meter “GretagMacbeth Spectroeye” (manufactured by Gretag), the average value was calculated as the image density (ID), and the image density was evaluated according to the following evaluation criteria.

◎: Image density is 1.2 or more ○: Image density is 1.1 or more, less than 1.2 △: Image density is 1.0 or more, less than 1.1 ×: Image density is less than 1.0

[Image unevenness]
The presence or absence of unevenness in the solid image was visually observed and evaluated according to the following evaluation criteria.

A: There is no unevenness.
○: There is almost no unevenness.
Δ: There is a little unevenness.
X: There is unevenness.

  Based on the above results, the toners of Examples 1 and 2 to which an intercalation compound intercalated with an ionic organic component was externally added were compared with the toners of Comparative Examples 1 to 4, and were continuously printed on a high-speed image forming apparatus. Also, it can be seen that a stable image without image unevenness is obtained without reducing the image density.

  The electrophotographic toner of the present invention is used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

Claims (7)

  An electrophotographic toner comprising toner base particles containing a binder resin, a charge control agent and a colorant and an external additive, wherein the external additive is ionic between layers of a clay mineral having a layered structure. An electrophotographic toner comprising an intercalation compound in which an organic component is intercalated.   2. The toner for electrophotography according to claim 1, wherein the clay mineral is a silicate clay mineral. The ionic organic component is of formula (I):

(In the formula, R ^{1 to} R ⁴ may be the same or different, and an alkyl group having 1 to 30 carbon atoms, an alkylphenyl group having 7 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms, X ⁻ is Anion)
The toner for electrophotography according to claim 1, which is a quaternary ammonium salt represented by the formula:   The toner for electrophotography according to any one of claims 1 to 3, wherein an average particle size of the intercalation compound is 0.1 to 2 µm.   The electrophotographic toner according to claim 1, wherein the binder resin contains polyester.   The electrophotographic toner according to claim 1, which is used in an image forming apparatus having a linear velocity of 400 mm / sec or more.   A two-component developer comprising the electrophotographic toner according to claim 1 and a carrier.