WO2015064632A1 - Hydrophobized spherical silica micropowder and use thereof - Google Patents

Hydrophobized spherical silica micropowder and use thereof Download PDF

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Publication number
WO2015064632A1
WO2015064632A1 PCT/JP2014/078741 JP2014078741W WO2015064632A1 WO 2015064632 A1 WO2015064632 A1 WO 2015064632A1 JP 2014078741 W JP2014078741 W JP 2014078741W WO 2015064632 A1 WO2015064632 A1 WO 2015064632A1
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Prior art keywords
spherical silica
silica fine
fine powder
less
hydrophobized
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PCT/JP2014/078741
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French (fr)
Japanese (ja)
Inventor
修治 佐々木
貴久 水本
慧 平田
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電気化学工業株式会社
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Priority to JP2015545264A priority Critical patent/JP6429791B2/en
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/097—Plasticisers; Charge controlling agents
    • G03G9/09708—Inorganic compounds
    • G03G9/09725—Silicon-oxides; Silicates
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions
    • C01P2004/32—Spheres
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/11—Powder tap density

Definitions

  • the present invention relates to a hydrophobized spherical silica fine powder, a production method thereof and use thereof.
  • silica fine powder has been used as an external additive to improve fluidity and stabilize charging characteristics. ing.
  • the characteristics required for this silica fine powder are that it has high hydrophobicity in order to reduce the change in charge amount due to humidity, and that the toner surface can be uniformly coated and that there is little aggregation and high dispersion.
  • the specific surface area of the silica fine powder an ultrafine powder of about 200 to 500 m 2 / g is used, but as the image is repeatedly formed, the silica ultrafine powder is embedded in the toner particle surface, and the toner It has been confirmed that the fluidity, triboelectric charge amount, transferability, and the like of the toner deteriorate and cause image defects.
  • Patent Document 1 Patent Document 2
  • Patent Document 2 Patent Document 2
  • inorganic fine powder having a specific surface area of less than 80 m 2 / g and a relatively large particle diameter is used in combination.
  • An inorganic fine powder having a relatively large particle size exhibits a spacer effect that reduces stress caused by direct contact between toners. In this way, a method of suppressing the burying of the ultrafine silica powder and extending the life of the toner is taken.
  • Patent Document 3 In the fluidity of the toner, if the amount of the inorganic fine powder having a relatively large particle size is increased, the fluidity is deteriorated.
  • Patent Document 3 a method in which 20 to 100 m 2 / g of fumed silica is surface-treated in the presence of an amine catalyst using an alkylalkoxysilane having a hexyl group or less.
  • externally added charge control particles obtained by applying a charge control agent to hydrophobic spherical silica fine particles of 20 to 500 nm obtained by hydrophobizing hydrophilic spherical silica fine particles obtained by the sol-gel method have a triboelectric charge amount.
  • Patent Document 4 It has been proposed (Patent Document 4) as a method of keeping a certain range.
  • Patent Document 1 the inorganic fine powder having a relatively large particle size tends to have a smaller charge amount than the ultrafine powder, and the external addition amount is increased in order to improve the spacer effect. As a result, the charge amount decreases.
  • Patent Document 3 if the amount of external addition is increased due to the shape of fumed silica and aggregation due to alkylsilane, the fluidity may be deteriorated.
  • Patent Document 4 it cannot be said that the spacer effect for reducing the stress caused by direct contact between toners is sufficient, and the charge amount may decrease due to the removal of the charge control agent due to repeated use.
  • An object of the present invention is to provide a hydrophobized spherical silica fine powder suitable for producing a toner external additive excellent in charge stability, fluidity, spacer effect and charge amount.
  • the present inventor has intensively studied to achieve the above object, and has succeeded in controlling the powder resistance, the water content, and the tap density, and has found a hydrophobized spherical silica fine powder that achieves this.
  • the present invention is based on such knowledge, and the present invention employs the following means (1) in order to solve the above-mentioned problems.
  • the powder resistance is 1.0 ⁇ 10 13 ⁇ ⁇ cm or more and 3.0 ⁇ 10 14 ⁇ ⁇ cm or less
  • the water content is 0.5 wt% or less
  • the tap density is 0.10 g / cm 3.
  • a hydrophobized spherical silica fine powder characterized by being 0.40 g / cm 3 or more.
  • the following means are employed.
  • the average particle size of the hydrophobized spherical silica fine powder measured by a laser diffraction / scattering particle size distribution analyzer is 0.080 ⁇ m or more and 0.200 ⁇ m or less, and the maximum particle size of the hydrophobized spherical silica fine powder
  • the spherical silica fine powder has a water content of 0.4 wt% or less, an average particle size measured by a laser diffraction / scattering particle size distribution analyzer of 0.070 ⁇ m to 0.170 ⁇ m, and the maximum
  • a toner external additive for developing an electrostatic charge image comprising the hydrophobized spherical silica fine powder described in any one of (1) to (3) above.
  • a hydrophobic spherical silica fine powder suitable for producing a toner external additive excellent in charge stability, fluidity, spacer effect, and charge amount is provided.
  • the hydrophobized spherical silica fine powder needs to have a powder resistance of 1.0 ⁇ 10 13 ⁇ ⁇ cm or more and 3.0 ⁇ 10 14 ⁇ ⁇ cm or less.
  • the powder resistance is less than 1.0 ⁇ 10 13 ⁇ ⁇ cm, the charge amount becomes small, and there is a problem that the toner charge amount decreases when used as an external toner additive.
  • Preferable powder resistance is 1.5 ⁇ 10 13 ⁇ ⁇ cm or more and 2.5 ⁇ 10 14 ⁇ ⁇ cm or less, and more preferably 2.0 ⁇ 10 13 ⁇ ⁇ cm or more and 2.0 ⁇ 10 14 ⁇ ⁇ cm or less. It is.
  • the powder resistance is, for example, 1.5 ⁇ 10 13 , 1.6 ⁇ 10 13 , 2.0 ⁇ 10 13 , 5.0 ⁇ 10 13 , 1.0 ⁇ 10 14 , 1.9 ⁇ 10 14 , 2.0 ⁇ 10 14 , 2.1 ⁇ 10 14 , 2.5 It may be ⁇ 10 14 , 2.9 ⁇ 10 14 , or 3.0 ⁇ 10 14 ⁇ ⁇ cm, and may be within the range of any two of them.
  • the powder resistance of the hydrophobized spherical silica fine powder can be measured using “Powder Resistance Measurement System MCP-PD51, 4-probe probe” manufactured by Mitsubishi Chemical Analytech. After 2.0 g of hydrophobized spherical silica powder was allowed to stand for 24 hours under conditions of a temperature of 25 ° C. and a relative humidity of 55%, it was filled in a measurement mold of ⁇ 20 mm and measured under a pressure of 38.2 MPa. The applied voltage was 1000 V and the voltage application time was 20 seconds.
  • the hydrophobized spherical silica fine powder needs to have a water content of 0.5 wt% or less.
  • the amount of moisture affects the magnitude of the charge amount and the environmental difference (difference in charge amount between high temperature and high humidity and low temperature and low humidity).
  • a preferable water content is 0.4 wt% or less, more preferably 0.3 wt% or less.
  • the amount of water may be, for example, 0.5, 0.4, 0.3, 0.2, 0.1, 0.05, or 0.01 wt% or less, or may be in the range of any two values thereof.
  • the water content of the hydrophobized spherical silica fine powder can be measured using the Karl Fischer method.
  • Karl Fischer measurement a moisture vaporizer VA-122 manufactured by Mitsubishi Chemical Corporation and a moisture analyzer CA-100 manufactured by Mitsubishi Chemical Corporation are used.
  • Aquamicron AX manufactured by Mitsubishi Chemical Corporation
  • catholyte is used as the anolyte of the moisture analyzer.
  • Aquamicron CXU Mitsubishi Chemical Corporation was used.
  • the background value was fixed at 0.20 ( ⁇ g / sec), and the measurement was continued until the detected water content fell below the background value.
  • the hydrophobized spherical silica fine powder is not exposed to the outside air, and the moisture generated from the moisture vaporizer is introduced into the Karl Fischer device along with 300 ml / min of high-purity argon. The amount was measured.
  • the hydrophobized spherical silica fine powder is allowed to stand for 24 hours at a temperature of 25 ° C. and a relative humidity of 55%, and then charged into the device until the heating temperature of the electric heater of the moisture vaporizer reaches 200 ° C.
  • the amount of water generated was defined as the amount of water.
  • the hydrophobized spherical silica fine powder needs to have a tap density of 0.10 g / cm 3 or more and 0.40 g / cm 3 or less.
  • the tap density is less than 0.10 g / cm 3
  • the tap density exceeds 0.40 g / cm 3
  • Preferred tap density is at 0.13 g / cm 3 or more 0.35 g / cm 3 or less, more preferably 0.15 g / cm 3 or more 0.30 g / cm 3 or less.
  • the tap density may be, for example, 0.10, 0.11, 0.15, 0.19, 0.20, 0.21, 0.25, 0.29, 0.30, 0.31, 0.35, 0.39, or 0.40 g / cm 3 , and any two values thereof It may be within the range.
  • the tap density of the hydrophobized spherical silica fine powder can be measured using a powder tester.
  • a powder tester As a measuring device, “PT-E type” manufactured by Hosokawa Micron Corporation was used. Hydrophobized spherical silica fine powder that was allowed to stand for 24 hours under conditions of a temperature of 25 ° C. and a relative humidity of 55% was placed in a 100 ml cup, and the apparent density was measured after tapping 180 times at a rate of once per second.
  • the hydrophobized spherical silica fine powder preferably has an average particle size of 0.080 ⁇ m or more and 0.200 ⁇ m or less as measured by a laser diffraction / scattering particle size distribution analyzer, and has a maximum particle size of It is preferable that it is 0.800 micrometer or less.
  • the average particle size is less than 0.080 ⁇ m, when used as an external toner additive, the spacer effect may be gradually lowered due to burying in the toner with time.
  • the average particle diameter exceeds 0.200 ⁇ m and / or the maximum particle diameter exceeds 0.800 ⁇ m, the fluidity of the toner external additive may be lowered due to the influence of the large diameter particles.
  • the average particle size is more preferably 0.085 ⁇ m or more and 0.180 ⁇ m or less, and most preferably 0.090 ⁇ m or more and 0.160 ⁇ m or less.
  • the maximum particle diameter is more preferably 0.700 ⁇ m or less, and most preferably 0.600 ⁇ m or less.
  • the particle size distribution of the hydrophobized spherical silica fine powder can be measured using “LS-230” manufactured by Beckman Coulter.
  • ethanol was used as a solvent, and dispersion treatment was performed with an output of 200 W using “Ultrasonic Generator UD-200 (with ultra-trace chip TP-040)” manufactured by Tommy Seiko Co., Ltd. for 3 minutes as a pretreatment.
  • concentration of PIDS Polygonalization Intensity Differential Scattering
  • the refractive index of ethanol was 1.36
  • the refractive index of hydrophobized spherical silica fine powder was 1.50.
  • particles having a cumulative mass of 50% are the average particle size
  • a particle size having a cumulative mass of 100% is the maximum particle size.
  • the hydrophobized spherical silica fine powder has particles having a projected area equivalent circle diameter of 0.100 ⁇ m or more measured by microscopy having an average sphericity of 0.88 or more, and a projected area equivalent circle diameter measured by microscopy of 0.
  • the number ratio of particles having a sphericity of 0.85 or less is 20% or less
  • the total number of particles having a projected area equivalent circle diameter of 0.100 ⁇ m or more by microscopy is 100%.
  • the number ratio of the particles of 0.80 or less is preferably 10% or less.
  • Particles with low sphericity often have a structure structure or form aggregates, and the tendency becomes more pronounced as the sphericity decreases.
  • particles having a projected area equivalent circle diameter of 0.100 ⁇ m or more measured by a microscopic method have an average sphericity of 0.88 or more and the total number of particles projected by a microscope projected area equivalent diameter of 0.100 ⁇ m or more is 100%, If the number ratio of particles having a sphericity of 0.85 or less is 20% or less and the number ratio of particles having a sphericity of 0.80 or less is 10% or less, there are few structure structure particles and aggregates, and the toner is used as an external toner additive. Better charging stability can be achieved.
  • the average sphericity of particles having a projected area equivalent circle diameter of 0.100 ⁇ m or more measured by microscopy is more preferably 0.90 or more, and most preferably 0.92 or more. Further, when the total number of particles having a projected area equivalent circle diameter of 0.100 ⁇ m or more measured by microscopy is 100%, the number ratio of particles having a sphericity of 0.85 or less is 15% or less and the sphericity is 0.80 or less. The number ratio is more preferably 8% or less, the number ratio of particles having a sphericity of 0.85 or less is most preferably 10%, and the number ratio of particles having a sphericity of 0.80 or less is most preferably 6% or less.
  • the sphericity of the hydrophobized spherical silica fine powder can be measured by the following method. After fixing the hydrophobized spherical silica powder to the sample stage with carbon paste, osmium coating was performed, and an image taken with a scanning electron microscope “JSM-6301F type” manufactured by JEOL Ltd. with a magnification of 50000 times and a resolution of 2048 ⁇ 1356 pixels I imported it into my computer. This image was taken into an image analysis apparatus “MacView Ver. 4” manufactured by Mountec Co., Ltd., and the sphericity was measured from the projected area (A) and the perimeter (PM) of the particles.
  • JSM-6301F type manufactured by JEOL Ltd.
  • the sphericity of 200 particles having an arbitrary projected area equivalent circle diameter of 0.100 ⁇ m or more thus obtained was determined, and the average value was taken as the average sphericity. Further, the ratio of the number of each particle was calculated from the number of particles having a sphericity of 0.85 or less, or 0.80 or less in these 200 particles.
  • the method for hydrophobizing spherical silica fine powder in one embodiment of the present invention will be described.
  • the inventor Prior to hydrophobizing with hexamethyldisilazane, the inventor activated silanol groups by preliminarily adsorbing moisture on the surface of the spherical silica fine powder, and highly reacted hexamethyldisilazane on the surface of the spherical silica fine powder. It has been found that the charging stability of the hydrophobized spherical silica fine powder can be improved.
  • the present inventors further adsorbed hexamethyldisilazane into spherical silica by adsorbing moisture in the state of water vapor and under specific temperature and humidity conditions, rather than simply spraying and adsorbing water when adsorbing moisture. It was found that the surface of the fine powder could be bonded very uniformly with a high reaction rate, and the charging stability of the hydrophobized spherical silica fine powder could be further improved. In addition, it has been found that the occurrence of aggregation due to the influence of moisture can be remarkably reduced, and is effective in improving fluidity.
  • the hydrophobized spherical silica fine powder is produced by a method of hydrophobizing with hexamethyldisilazane at a temperature of 35 ° C. to 55 ° C. and an absolute humidity of 40 g / m 3 to 100 g / m 3. It is preferable to use fine spherical silica powder that has been allowed to stand for 24 hours or more under the following conditions. Before hydrophobizing with hexamethyldisilazane, the spherical silica fine powder is allowed to stand for 24 hours or more under conditions of a temperature of 35 ° C. or more and 55 ° C.
  • the amount of water present on the surface of the spherical silica fine powder is reduced, so that the uniform hydrophobicity when the hydrophobic treatment is performed with hexamethyldisilazane Therefore, when used as an external toner additive, the charging stability due to changes over time cannot be sufficiently improved.
  • the standing time is less than 24 hours, which is not preferable because the amount of water present on the surface of the spherical silica fine powder is reduced.
  • the temperature is higher than 55 ° C.
  • the spherical silica fine powder is agglomerated by the action of liquid crosslinking acting between the spherical silica fine powders. For this reason, when the hydrophobization treatment is performed with hexamethyldisilazane, the hydrophobicity inside the aggregate of the spherical silica fine powder is lowered, and as a result, the charging stability due to the change with time cannot be sufficiently improved.
  • the temperature is more preferably 37 ° C. or more and 53 ° C. or less, and most preferably 40 ° C. or more and 50 ° C. or less. Further, more preferably absolute humidity 45 g / m 3 or more 90 g / m 3 or less, 50 g / m 3 or more 80 g / m 3 or less is most preferred.
  • the spherical silica fine powder 1 m 2 per, 4.0 ⁇ 10 - It is preferable to spray 6 mol or more and 1.5 ⁇ 10 ⁇ 5 mol or less of hexamethyldisilazane.
  • the spray amount of hexamethyldisilazane is less than 4.0 ⁇ 10 ⁇ 6 mol per 1 m 2 of the spherical silica fine powder, the uniform hydrophobicity becomes insufficient and changes over time when used as an external toner additive. The charging stability due to cannot be sufficiently improved.
  • the spray amount of hexamethyldisilazane is more preferably 5.5 ⁇ 10 ⁇ 6 mol or more and 1.4 ⁇ 10 ⁇ 5 mol or less, and 7.0 ⁇ 10 ⁇ 6 mol or more per 1 m 2 of spherical silica fine powder. Most preferred is 3 ⁇ 10 ⁇ 5 mol or less.
  • the hexamethyldisilazane spraying method is, for example, a method of spraying the stock solution in a state where the spherical silica fine powder raw material is suspended, or a method of spraying hexamethyldisilazane and then gasifying and contacting the spherical silica fine powder. There is.
  • hexamethyldisilazane may be treated alone with respect to the spherical silica fine powder raw material, or treated with two or more kinds of surface treatment agents. You may do it.
  • the aminosilane coupling agent is used in combination with an aminosilane coupling agent for imparting positive chargeability, first, the aminosilane treatment is performed on the spherical silica fine powder, and then the hydrophobization treatment method in one embodiment of the present invention may be performed.
  • the hydrophobized spherical silica fine powder in one embodiment of the present invention preferably has a hydrophobization degree of 50% or more. If the degree of hydrophobicity is less than 50%, the charging characteristics of the toner in a high-humidity environment are deteriorated, or the toner particles are aggregated to decrease the fluidity. More preferably 55% or more, and most preferably 60% or more.
  • the degree of hydrophobicity can be measured by the following method. That is, 50 ml of ion-exchanged water and 0.2 g of a sample are put in a beaker, and methanol is dropped from a burette while stirring with a magnetic stirrer.
  • the powder gradually settles, and the volume% of methanol in the mixed solution of methanol and ion-exchanged water at the end point when the total amount of the powder is settled is defined as the degree of hydrophobicity (%).
  • the spherical silica fine powder used in the method for producing a hydrophobized spherical silica fine powder in one embodiment of the present invention is obtained by oxidizing metal silicon in order to realize the hydrophobized spherical silica fine powder having the water content and sphericity of the present invention. It is preferable to use the spherical silica fine powder obtained in (1).
  • a method for producing spherical silica fine powder a method in which metal silicon is spheroidized while being subjected to an oxidation reaction by being applied to a high temperature field formed by a chemical flame or an electric furnace (for example, Japanese Patent No. 1568168), metal silicon Examples thereof include a method in which a particle slurry is sprayed into a flame and spheroidized while undergoing an oxidation reaction (for example, JP-A-2000-247626).
  • the spherical silica fine powder used in the method for producing a hydrophobized spherical silica fine powder in one embodiment of the present invention has a water content of 0.4 wt% or less, and an average particle measured by a laser diffraction scattering type particle size distribution analyzer. It is preferable to use a fine spherical silica powder having a diameter of 0.070 ⁇ m or more and 0.170 ⁇ m or less and a maximum particle diameter of 0.300 ⁇ m or less.
  • the water content of the spherical silica fine powder is 0.4 wt% or less, the average particle size is 0.070 ⁇ m or more and 0.170 ⁇ m or less, and the maximum particle size is 0.300 ⁇ m or less, thereby making the hydrophobic spherical shape in one embodiment of the present invention. It becomes easy to realize a water content of silica fine powder of 0.5 wt% or less, an average particle size of 0.080 ⁇ m to 0.200 ⁇ m, and a maximum particle size of 0.800 ⁇ m or less.
  • the amount of the hydrophobized spherical silica fine powder blended in the toner according to an embodiment of the present invention is usually preferably 0.1 to 6 parts by mass, more preferably 0.3 to 4 parts by mass with respect to 100 parts by mass of the toner. Part. If the blending amount is too small, the adhesion amount to the toner is small and a sufficient spacer effect cannot be obtained. If the blending amount is too large, the hydrophobic spherical silica fine powder may be detached from the toner surface.
  • the silica powder of the toner external additive containing the hydrophobized spherical silica fine powder in one embodiment of the present invention is not limited to the use of the hydrophobized spherical silica fine powder in one embodiment of the present invention alone.
  • it can be used in combination with ultrafine powder silica of about 200 to 500 m 2 / g, which has a high fluidity-imparting effect.
  • the electrostatic image developing toner to which the toner external additive containing the spherical silica fine powder in one embodiment of the present invention is added a known toner composed mainly of a binder resin and a colorant can be used. . Moreover, the charge control agent may be added as needed.
  • the toner for developing an electrostatic image to which an external toner additive containing a hydrophobic spherical silica fine powder according to an embodiment of the present invention is added can be used as a one-component developer, and can be mixed with a carrier to form a two-component developer. It can also be used as a component developer.
  • the toner external additive may not be added to the toner particles in advance, but may be added when the toner and the carrier are mixed to coat the surface of the toner.
  • the carrier iron powder or the like, or a known one whose surface is resin-coated is used.
  • Examples 1 to 14 Comparative Examples 1 to 10 Spherical silica fine powder is manufactured using a device in which an LPG-oxygen mixed burner with a double pipe structure capable of forming an inner flame and an outer flame is installed at the top of the combustion furnace, and a collection system line is directly connected to the lower part. did. A two-fluid nozzle for slurry spraying is further installed at the center of the burner, and a slurry (metal silicon concentration: 10 to 70% by mass) composed of metal silicon powder (average particle size 10.5 ⁇ m) and water is formed from the center.
  • Table 1 shows the water content, average particle size, and maximum particle size of the fine spherical silica powder.
  • the obtained spherical silica fine powders were respectively placed in a constant temperature and humidity chamber (“EC-45MHP” manufactured by Hitachi Appliances) and left in the bath under various conditions.
  • Tables 1, 2, and 3 show the temperature, absolute humidity, and time when left in the tank.
  • each spherical silica fine powder taken out from the constant temperature and humidity chamber was immediately charged into a fluidized bed (Chuo Kakoki Co., Ltd. “vibrating fluidized bed apparatus VUA-15 type”) and fluidized with N 2 gas.
  • Silazane (“SZ-31” manufactured by Shin-Etsu Chemical Co., Ltd.) was sprayed in various spray amounts and fluidly mixed for 20 minutes. After fluid mixing, the temperature was raised to 130 ° C., and ammonia formed while removing nitrogen gas was removed to obtain hydrophobized spherical silica fine powders A to W.
  • hydrophobization treatment was performed in the same manner as above to obtain hydrophobized spherical silica fine powder X.
  • the spray amounts of hexamethyldisilazane are shown in Table 1, Table 2, and Table 3.
  • Compressibility (Fixed apparent specific gravity-Loose apparent specific gravity) / Fixed apparent specific gravity x 100 (%)
  • the loose apparent specific gravity is a specific gravity measured with a pseudo-toner placed in a 100 ml cup and without tapping.
  • the solid apparent specific gravity is a pseudo-toner put into a 100 ml cup at a rate of once per second.
  • the apparent specific gravity measured after tapping 180 times.
  • the compression time was measured by changing the mixing time of the Henschel mixer from 3 minutes to 30 minutes, and the compression ratio change ratio was calculated from the following equation.
  • Compressibility change ratio compression degree when mixing time is 30 minutes / compression degree when mixing time is 3 minutes
  • the compressibility change ratio is closer to 1, that is, the smaller the change in the compression degree, the better the spacer effect is Represents.
  • a simulated toner that was allowed to stand for 24 hours under the conditions of a temperature of 25 ° C. and a relative humidity of 55% was placed on a sieve having a mesh opening of 710 ⁇ m and deposited on a circular measuring table having a diameter of 8 cm through a funnel while applying vibration.
  • the angle of the line of the deposited powder with respect to the horizontal plane was defined as the angle of repose using a protractor. It shows that fluidity
  • the suction time was 3 minutes, the suction pressure was 4.0 kPa, and a screen of 32 ⁇ m mesh was used for the screen used for separating the simulated toner and the carrier.
  • Charge retention ratio Blow-off charge amount after 120 minutes of shaking / Blow-off charge amount after 5 minutes of shaking The value of this charge holding ratio is closer to 1, that is, the smaller the change in the charge amount, the more stable the charge is with time. Represents good.
  • External additive coverage per pseudo toner (total projected area of spherical silica fine powder adhering to the surface of one crosslinked styrene resin powder / projected area of one crosslinked styrene resin powder) ⁇ 100 (%) The external additive coverage was calculated for 20 pseudo toners, and the average value was taken as the average external additive coverage.
  • the hydrophobized spherical silica fine powder of the present invention is used as an external additive for electrophotographic toners used in copying machines, laser printers and the like.

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  • Inorganic Chemistry (AREA)
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Abstract

Provided is a hydrophobized spherical silica micropowder suitable for producing an external additive for a toner that excels in charge stability, flowability, spacer effect, and electrostatic properties. The hyrdophobized spherical silica micropowder is characterized in that powder resistance is 1.0×1013 Ω•cm to 3.0×1014 Ω•cm; moisture content is no more than 0.5wt%; and tap density is 0.10g/cm3 to 0.40g/cm3.

Description

疎水化球状シリカ微粉末及びその用途Hydrophobized spherical silica fine powder and use thereof
　本発明は、疎水化球状シリカ微粉末及びその製造方法とその用途に関する。 The present invention relates to a hydrophobized spherical silica fine powder, a production method thereof and use thereof.
　従来、デジタル複写機やレーザープリンター等に使用される静電荷像現像用トナーにおいて、その流動性改善や帯電特性の安定化のために、表面処理されたシリカ微粉体がトナー外添剤として用いられている。このシリカ微粉体に要求される特性は、湿度による帯電量の変化を少なくするため高い疎水性を有し、しかもトナー表面を均一に被覆できるように、凝集が少なく高分散であることである。シリカ微粉体の比表面積については、２００～５００ｍ２／ｇ程度の超微紛末が使用されるが、繰り返しの画像形成を行っていくうちにトナー粒子表面にシリカ超微粉末が埋没し、トナーの流動性、摩擦帯電量、転写性等が低下して画像不良を引き起こすことが確認されている。 Conventionally, in electrostatic toner image developing toners used in digital copying machines, laser printers, etc., surface-treated silica fine powder has been used as an external additive to improve fluidity and stabilize charging characteristics. ing. The characteristics required for this silica fine powder are that it has high hydrophobicity in order to reduce the change in charge amount due to humidity, and that the toner surface can be uniformly coated and that there is little aggregation and high dispersion. As for the specific surface area of the silica fine powder, an ultrafine powder of about 200 to 500 m 2 / g is used, but as the image is repeatedly formed, the silica ultrafine powder is embedded in the toner particle surface, and the toner It has been confirmed that the fluidity, triboelectric charge amount, transferability, and the like of the toner deteriorate and cause image defects.
　このシリカ超微粉末の埋没を低減させるため、比表面積８０ｍ２／ｇ未満の比較的粒子径の大きな無機微粉末を併用する方法（特許文献１、特許文献２）がある。比較的粒子径の大きな無機微粉末はトナー同士が直接接して生じるストレスを低減させるスペーサー効果を発現する。これにより、シリカ超微粉末の埋没を抑え、トナーの長寿命化を図る方法などがとられている。 In order to reduce the burying of the silica ultrafine powder, there is a method (Patent Document 1, Patent Document 2) in which inorganic fine powder having a specific surface area of less than 80 m 2 / g and a relatively large particle diameter is used in combination. An inorganic fine powder having a relatively large particle size exhibits a spacer effect that reduces stress caused by direct contact between toners. In this way, a method of suppressing the burying of the ultrafine silica powder and extending the life of the toner is taken.
　トナーの流動性において、比較的粒径の大きな無機微粉末の外添量を増加させると、流動性が悪化する問題がある。この問題の解決を狙い、２０～１００ｍ２／ｇのフュームドシリカをヘキシル基以下のアルキルアルコキシシランを用い、アミン系触媒の存在下で表面処理する方法（特許文献３）が提案されている。
　また、ゾルゲル法によって得られる親水性球状シリカ微粒子を疎水化処理して得られる２０～５００ｎｍの疎水性球状シリカ微粒子に電荷制御剤を被着せしめた外添用電荷制御粒子が、摩擦帯電量を一定範囲に保つ方法として提案（特許文献４）されている。 In the fluidity of the toner, if the amount of the inorganic fine powder having a relatively large particle size is increased, the fluidity is deteriorated. In order to solve this problem, there has been proposed a method (Patent Document 3) in which 20 to 100 m 2 / g of fumed silica is surface-treated in the presence of an amine catalyst using an alkylalkoxysilane having a hexyl group or less.
Further, externally added charge control particles obtained by applying a charge control agent to hydrophobic spherical silica fine particles of 20 to 500 nm obtained by hydrophobizing hydrophilic spherical silica fine particles obtained by the sol-gel method have a triboelectric charge amount. It has been proposed (Patent Document 4) as a method of keeping a certain range.
特開平５－３４６６８２号公報JP-A-5-346682 特開２０００－８１７２３号公報JP 2000-81723 A 特開２００４－２３１４９８号公報JP 2004-231498 A 特開２０１１－１８５９９８号公報JP 2011-185998 A
　しかしながら、特許文献１および特許文献２の方法において、比較的粒径の大きな無機微粉末は、超微粉末に比べて帯電量が小さい傾向があり、スペーサー効果向上を狙って外添量を増加させると帯電量の低下を招く。
　特許文献３では、フュームドシリカの形状、及びアルキルシランによる凝集により、外添量を増加させると流動性が悪化する恐れがある。
　特許文献４では、トナー同士が直接接して生じるストレスを低減させるスペーサー効果についてはまだ十分とは言えず、繰り返し使用による電荷制御剤の脱落により帯電量の低下を招く恐れがある。その為、比較的粒径の大きな微粉末の帯電特性、流動特性に対する更なる改善が求められている。
　本発明の目的は、帯電安定性、流動性、スペーサー効果、帯電量に優れたトナー外添剤を生産するために好適な疎水化球状シリカ微粉末を提供することである。 However, in the methods of Patent Document 1 and Patent Document 2, the inorganic fine powder having a relatively large particle size tends to have a smaller charge amount than the ultrafine powder, and the external addition amount is increased in order to improve the spacer effect. As a result, the charge amount decreases.
In Patent Document 3, if the amount of external addition is increased due to the shape of fumed silica and aggregation due to alkylsilane, the fluidity may be deteriorated.
In Patent Document 4, it cannot be said that the spacer effect for reducing the stress caused by direct contact between toners is sufficient, and the charge amount may decrease due to the removal of the charge control agent due to repeated use. For this reason, there is a need for further improvements to the charging characteristics and flow characteristics of fine powder having a relatively large particle size.
An object of the present invention is to provide a hydrophobized spherical silica fine powder suitable for producing a toner external additive excellent in charge stability, fluidity, spacer effect and charge amount.
　本発明者は、上記の目的を達成するべく鋭意研究を進めたところ、粉体抵抗、水分量、タップ密度を制御することに成功し、これを達成する疎水化球状シリカ微粉末を見いだした。本発明はかかる知見に基づくものであり、本発明は上記の課題を解決するために、下記（１）の手段を採用する。
　（１）粉体抵抗が１．０×１０１３Ω・ｃｍ以上３．０×１０１４Ω・ｃｍ以下であり、水分量が０．５ｗｔ％以下であり、タップ密度が０．１０ｇ／ｃｍ３以上０．４０ｇ／ｃｍ３以下であることを特徴とする疎水化球状シリカ微粉末。
　また、好ましくは、以下の手段を採用する。
　（２）前記疎水化球状シリカ微粉末のレーザー回折散乱式粒度分布測定機にて測定された平均粒子径が０．０８０μｍ以上０．２００μｍ以下であり、前記疎水化球状シリカ微粉末の最大粒子径が０．８００μｍ以下であることを特徴とする前記（１）に記載の疎水化球状シリカ微粉末。
　（３）前記疎水化球状シリカ微粉末において顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子は、平均球形度０．８８以上であり、
　前記顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子の総数を１００%とした場合、球形度０．８５以下の粒子個数割合が２０％以下であり、
　前記顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子の総数を１００%とした場合、球形度０．８０以下の粒子個数割合が１０％以下であることを特徴とする前記（１）又は（２）に記載の疎水化球状シリカ微粉末。
　（４）温度３５℃以上５５℃以下、絶対湿度４０ｇ／ｍ３以上１００ｇ／ｍ３以下の条件下で２４時間以上放置した球状シリカ微粉末に、前記球状シリカ微粉末１ｍ２当たり、４．０×１０－６ｍｏｌ以上１．５×１０－５ｍｏｌ以下のヘキサメチルジシラザンを噴霧することを特徴とする前記（１）から（３）のいずれか１項に記載の疎水化球状シリカ微粉末の製造方法。
　（５）前記球状シリカ微粉末は、水分量が０．４ｗｔ％以下であり、レーザー回折散乱式粒度分布測定機にて測定された平均粒子径が０．０７０μｍ以上０．１７０μｍ以下であり、最大粒子径が０．３００μｍ以下であることを特徴とする前記（１）に記載の疎水化球状シリカ微粉末の製造方法。
　（６）前記（１）から（３）のいずれか１項に記載の疎水化球状シリカ微粉末を含有することを特徴とする静電荷像現像用トナー外添剤。 The present inventor has intensively studied to achieve the above object, and has succeeded in controlling the powder resistance, the water content, and the tap density, and has found a hydrophobized spherical silica fine powder that achieves this. The present invention is based on such knowledge, and the present invention employs the following means (1) in order to solve the above-mentioned problems.
(1) The powder resistance is 1.0 × 10 13 Ω · cm or more and 3.0 × 10 14 Ω · cm or less, the water content is 0.5 wt% or less, and the tap density is 0.10 g / cm 3. A hydrophobized spherical silica fine powder characterized by being 0.40 g / cm 3 or more.
Preferably, the following means are employed.
(2) The average particle size of the hydrophobized spherical silica fine powder measured by a laser diffraction / scattering particle size distribution analyzer is 0.080 μm or more and 0.200 μm or less, and the maximum particle size of the hydrophobized spherical silica fine powder The hydrophobized spherical silica fine powder as described in (1) above, wherein the hydrophobized spherical silica fine powder is 0.800 μm or less.
(3) Particles having a projected area equivalent circle diameter of 0.100 μm or more in the hydrophobized spherical silica fine powder have an average sphericity of 0.88 or more,
When the total number of particles having a projected area equivalent circle diameter of 0.100 μm or more by the microscopic method is 100%, the ratio of the number of particles having a sphericity of 0.85 or less is 20% or less,
(1) or (1), wherein the ratio of the number of particles having a sphericity of 0.80 or less is 10% or less, assuming that the total number of particles having an equivalent circle diameter of 0.100 μm or more by the microscopic method is 100% The hydrophobized spherical silica fine powder according to (2).
(4) 4.0 g / m 2 of the spherical silica fine powder was added to the spherical silica fine powder left for 24 hours or more under the conditions of a temperature of 35 ° C. to 55 ° C. and an absolute humidity of 40 g / m 3 to 100 g / m 3. 4. Hydrophobized spherical silica fine powder according to any one of (1) to (3), characterized in that hexamethyldisilazane is sprayed in a range of × 10 −6 mol to 1.5 × 10 −5 mol. Manufacturing method.
(5) The spherical silica fine powder has a water content of 0.4 wt% or less, an average particle size measured by a laser diffraction / scattering particle size distribution analyzer of 0.070 μm to 0.170 μm, and the maximum The method for producing a hydrophobized spherical silica fine powder as described in (1) above, wherein the particle diameter is 0.300 μm or less.
(6) A toner external additive for developing an electrostatic charge image, comprising the hydrophobized spherical silica fine powder described in any one of (1) to (3) above.
　本発明によれば、帯電安定性、流動性、スペーサー効果、帯電量に優れたトナー外添剤を生産するために好適な疎水化球状シリカ微粉末が提供される。 According to the present invention, a hydrophobic spherical silica fine powder suitable for producing a toner external additive excellent in charge stability, fluidity, spacer effect, and charge amount is provided.
　以下、本発明の実施形態を詳細に説明する。
　本発明の一実施形態において疎水化球状シリカ微粉末は、粉体抵抗が１．０×１０１３Ω・ｃｍ以上３．０×１０１４Ω・ｃｍ以下であることが必要である。粉体抵抗が１．０×１０１３Ω・ｃｍ未満であると、帯電量が小さくなり、トナー外添剤に使用した際に、トナー帯電量が低下する問題が発生する。一方、粉体抵抗が３．０×１０１４Ω・ｃｍを超えると、初期の帯電量は大きくなるものの、経時変化による帯電劣化が大きくなり、トナー外添剤として使用した際に、印字特性の経時安定性が悪化する問題が発生する。好ましい粉体抵抗は１．５×１０１３Ω・ｃｍ以上２．５×１０１４Ω・ｃｍ以下、より好ましくは、２．０×１０１３Ω・ｃｍ以上２．０×１０１４Ω・ｃｍ以下である。また、粉体抵抗は、例えば、1.5×1013、1.6×1013、2.0×1013、5.0×1013、1.0×1014、1.9×1014、2.0×1014、2.1×1014、2.5×1014、2.9×1014、又は3.0×1014Ω・ｃｍであってもよく、それらいずれか2つの値の範囲内であっても良い。 Hereinafter, embodiments of the present invention will be described in detail.
In one embodiment of the present invention, the hydrophobized spherical silica fine powder needs to have a powder resistance of 1.0 × 10 13 Ω · cm or more and 3.0 × 10 14 Ω · cm or less. When the powder resistance is less than 1.0 × 10 13 Ω · cm, the charge amount becomes small, and there is a problem that the toner charge amount decreases when used as an external toner additive. On the other hand, if the powder resistance exceeds 3.0 × 10 14 Ω · cm, the initial charge amount increases, but the charge deterioration due to aging increases, and when used as a toner external additive, There arises a problem that the stability over time deteriorates. Preferable powder resistance is 1.5 × 10 13 Ω · cm or more and 2.5 × 10 14 Ω · cm or less, and more preferably 2.0 × 10 13 Ω · cm or more and 2.0 × 10 14 Ω · cm or less. It is. The powder resistance is, for example, 1.5 × 10 13 , 1.6 × 10 13 , 2.0 × 10 13 , 5.0 × 10 13 , 1.0 × 10 14 , 1.9 × 10 14 , 2.0 × 10 14 , 2.1 × 10 14 , 2.5 It may be × 10 14 , 2.9 × 10 14 , or 3.0 × 10 14 Ω · cm, and may be within the range of any two of them.
　本発明の一実施形態において疎水化球状シリカ微粉末の粉体抵抗は、三菱化学アナリテック社製「粉体抵抗測定システムＭＣＰ‐ＰＤ５１、４探針プローブ」を用いて測定することが出来る。疎水化球状シリカ粉末２．０ｇを、温度２５℃、相対湿度５５％の条件下で２４Ｈｒ静置した後、φ２０ｍｍの測定用金型に充填し、３８．２ＭＰａの加圧下で測定を行った。また、印加電圧は１０００Ｖ、電圧印加時間は２０秒とした。 In one embodiment of the present invention, the powder resistance of the hydrophobized spherical silica fine powder can be measured using “Powder Resistance Measurement System MCP-PD51, 4-probe probe” manufactured by Mitsubishi Chemical Analytech. After 2.0 g of hydrophobized spherical silica powder was allowed to stand for 24 hours under conditions of a temperature of 25 ° C. and a relative humidity of 55%, it was filled in a measurement mold of φ20 mm and measured under a pressure of 38.2 MPa. The applied voltage was 1000 V and the voltage application time was 20 seconds.
　本発明の一実施形態において疎水化球状シリカ微粉末は、水分量が０．５ｗｔ％以下であることが必要である。水分量は、トナー外添剤に使用した際に、帯電量の大きさと環境差（高温高湿下と低温低湿化での帯電量の差）に影響を及ぼす。水分量が多くなり、０．５ｗｔ％を超えると、帯電量が低下し、環境差の悪化も招く。好ましい水分量は０．４ｗｔ％以下であり、より好ましくは０．３ｗｔ％以下である。また、水分量は、例えば、0.5、0.4、0.3、0.2、0.1、0.05又は0.01ｗｔ％以下であってもよく、それらいずれか2つの値の範囲内であっても良い。 In one embodiment of the present invention, the hydrophobized spherical silica fine powder needs to have a water content of 0.5 wt% or less. When used as an external toner additive, the amount of moisture affects the magnitude of the charge amount and the environmental difference (difference in charge amount between high temperature and high humidity and low temperature and low humidity). When the amount of water increases and exceeds 0.5 wt%, the amount of charge decreases and the environmental difference is worsened. A preferable water content is 0.4 wt% or less, more preferably 0.3 wt% or less. Further, the amount of water may be, for example, 0.5, 0.4, 0.3, 0.2, 0.1, 0.05, or 0.01 wt% or less, or may be in the range of any two values thereof.
　本発明の一実施形態において疎水化球状シリカ微粉末の水分量は、カールフィッシャー法を用いて測定することが出来る。カールフィッシャー測定には三菱化学社製水分気化装置ＶＡ－１２２と三菱化学社製水分測定装置ＣＡ－１００を使用し、水分測定装置の陽極液にはアクアミクロンＡＸ（三菱化学社製）、陰極液にはアクアミクロンＣＸＵ（三菱化学社製）を使用した。カールフィッシャー測定に際してはバックグラウンド値を０．２０（μｇ／ｓｅｃ）に固定し、検出される水分がバックグラウンド値を下回るまで継続して測定を行った。水分気化装置の電気ヒーターによる加熱処理時は疎水化球状シリカ微粉末が外気にさらさないようにし、水分気化装置から発生した水分を高純度アルゴン３００ｍｌ／ｍｉｎに同伴させカールフィッシャー装置に導入し、水分量を測定した。本発明においては、疎水化球状シリカ微粉末を、温度２５℃、相対湿度５５％の条件下で２４Ｈｒ静置させた後に装置に仕込み、水分気化装置の電気ヒーターの加熱温度が２００℃となるまでに発生した水分を水分量とした。 In one embodiment of the present invention, the water content of the hydrophobized spherical silica fine powder can be measured using the Karl Fischer method. For Karl Fischer measurement, a moisture vaporizer VA-122 manufactured by Mitsubishi Chemical Corporation and a moisture analyzer CA-100 manufactured by Mitsubishi Chemical Corporation are used. Aquamicron AX (manufactured by Mitsubishi Chemical Corporation), catholyte is used as the anolyte of the moisture analyzer. Aquamicron CXU (Mitsubishi Chemical Corporation) was used. In the Karl Fischer measurement, the background value was fixed at 0.20 (μg / sec), and the measurement was continued until the detected water content fell below the background value. During the heat treatment with the electric heater of the moisture vaporizer, the hydrophobized spherical silica fine powder is not exposed to the outside air, and the moisture generated from the moisture vaporizer is introduced into the Karl Fischer device along with 300 ml / min of high-purity argon. The amount was measured. In the present invention, the hydrophobized spherical silica fine powder is allowed to stand for 24 hours at a temperature of 25 ° C. and a relative humidity of 55%, and then charged into the device until the heating temperature of the electric heater of the moisture vaporizer reaches 200 ° C. The amount of water generated was defined as the amount of water.
　本発明の一実施形態において疎水化球状シリカ微粉末は、タップ密度が０．１０ｇ／ｃｍ３以上０．４０ｇ／ｃｍ３以下であることが必要である。タップ密度が０．１０ｇ／ｃｍ３未満であると、トナー外添剤として使用した際に、トナー樹脂表面の疎水化球状シリカ微粉末被覆率が低くなりやすく、スペーサー効果が低下する問題がある。一方、タップ密度が０．４０ｇ／ｃｍ３を超えると、疎水化表面処理を行う際に均一処理を行うことが困難となり、経時変化による帯電劣化が大きくなる問題がある。好ましいタップ密度は０．１３ｇ／ｃｍ３以上０．３５ｇ／ｃｍ３以下であり、より好ましくは０．１５ｇ／ｃｍ３以上０．３０ｇ／ｃｍ３以下である。また、タップ密度は、例えば、0.10、0.11、0.15、0.19、0.20、0.21、0.25、0.29、0.30、0.31、0.35、0.39、又は0.40ｇ／ｃｍ３であってもよく、それらいずれか2つの値の範囲内であっても良い。 In one embodiment of the present invention, the hydrophobized spherical silica fine powder needs to have a tap density of 0.10 g / cm 3 or more and 0.40 g / cm 3 or less. When the tap density is less than 0.10 g / cm 3 , when used as an external toner additive, there is a problem in that the coverage of the hydrophobic spherical silica fine powder on the surface of the toner resin tends to be low, and the spacer effect is lowered. On the other hand, when the tap density exceeds 0.40 g / cm 3 , it is difficult to perform uniform treatment when performing the hydrophobized surface treatment, and there is a problem that charging deterioration due to change with time increases. Preferred tap density is at 0.13 g / cm 3 or more 0.35 g / cm 3 or less, more preferably 0.15 g / cm 3 or more 0.30 g / cm 3 or less. The tap density may be, for example, 0.10, 0.11, 0.15, 0.19, 0.20, 0.21, 0.25, 0.29, 0.30, 0.31, 0.35, 0.39, or 0.40 g / cm 3 , and any two values thereof It may be within the range.
　本発明の一実施形態において疎水化球状シリカ微粉末のタップ密度はパウダテスターを用いて測定することが出来る。測定装置には、ホソカワミクロン社製「ＰＴ－Ｅ型」を使用した。温度２５℃、相対湿度５５％の条件下で２４Ｈｒ静置させた疎水化球状シリカ微粉末を１００ｍｌのカップに入れ、１秒に１回の速さで１８０回タッピング後に見掛け密度を測定した。 In one embodiment of the present invention, the tap density of the hydrophobized spherical silica fine powder can be measured using a powder tester. As a measuring device, “PT-E type” manufactured by Hosokawa Micron Corporation was used. Hydrophobized spherical silica fine powder that was allowed to stand for 24 hours under conditions of a temperature of 25 ° C. and a relative humidity of 55% was placed in a 100 ml cup, and the apparent density was measured after tapping 180 times at a rate of once per second.
　本発明の一実施形態において疎水化球状シリカ微粉末は、レーザー回折散乱式粒度分布測定機にて測定された平均粒子径が０．０８０μｍ以上０．２００μｍ以下であることが好ましく、最大粒子径が０．８００μｍ以下であることが好ましい。平均粒子径が０．０８０μｍ未満であると、トナー外添剤に使用した際に、経時変化に伴いトナーへの埋没が起こってスペーサー効果が徐々に低下する可能性がある。一方、平均粒子径が０．２００μｍを超、及び／又は最大粒子径が０．８００μｍを超えると、大径粒子の影響で、トナー外添剤の流動性が低下する可能性がある。平均粒子径は０．０８５μｍ以上０．１８０μｍ以下が更に好ましく、０．０９０μｍ以上０．１６０μｍ以下は最も好ましい。また、最大粒子径は０．７００μｍ以下が更に好ましく、０．６００μｍ以下が最も好ましい。 In one embodiment of the present invention, the hydrophobized spherical silica fine powder preferably has an average particle size of 0.080 μm or more and 0.200 μm or less as measured by a laser diffraction / scattering particle size distribution analyzer, and has a maximum particle size of It is preferable that it is 0.800 micrometer or less. When the average particle size is less than 0.080 μm, when used as an external toner additive, the spacer effect may be gradually lowered due to burying in the toner with time. On the other hand, if the average particle diameter exceeds 0.200 μm and / or the maximum particle diameter exceeds 0.800 μm, the fluidity of the toner external additive may be lowered due to the influence of the large diameter particles. The average particle size is more preferably 0.085 μm or more and 0.180 μm or less, and most preferably 0.090 μm or more and 0.160 μm or less. The maximum particle diameter is more preferably 0.700 μm or less, and most preferably 0.600 μm or less.
　本発明の一実施形態において疎水化球状シリカ微粉末のレーザー回折散乱式粒度分布は、ベックマンコールター社製「ＬＳ－２３０」を用いて測定することができる。測定に際しては、溶媒にはエタノールを用い、前処理として３分間、トミー精工社製「超音波発生器ＵＤ－２００（超微量チップＴＰ－０４０装着）」を用いて２００Ｗの出力をかけて分散処理する。また、ＰＩＤＳ（Ｐｏｌａｒｉｚａｔｉｏｎ　Ｉｎｔｅｎｓｉｔｙ　Ｄｉｆｆｅｒｅｎｔｉａｌ　Ｓｃａｔｔｅｒｉｎｇ）濃度を４５～５５質量％に調整する。粒度分布の解析は０．０４～２０００μｍの範囲を粒子径チャンネルがｌｏｇ（μｍ）＝０．０４の幅で１１６分割にして行った。エタノールの屈折率には１．３６を用い、疎水化球状シリカ微粉末の屈折率には１．５０を用いた。
　なお、本発明では測定した粒度分布において、累積質量が５０％となる粒子が平均粒子径、累積質量が１００％となる粒子径が最大粒子径である。 In one embodiment of the present invention, the particle size distribution of the hydrophobized spherical silica fine powder can be measured using “LS-230” manufactured by Beckman Coulter. In the measurement, ethanol was used as a solvent, and dispersion treatment was performed with an output of 200 W using “Ultrasonic Generator UD-200 (with ultra-trace chip TP-040)” manufactured by Tommy Seiko Co., Ltd. for 3 minutes as a pretreatment. To do. In addition, the concentration of PIDS (Polarization Intensity Differential Scattering) is adjusted to 45 to 55% by mass. The analysis of the particle size distribution was performed by dividing the range of 0.04 to 2000 μm into 116 divisions with the width of the particle diameter channel being log (μm) = 0.04. The refractive index of ethanol was 1.36, and the refractive index of hydrophobized spherical silica fine powder was 1.50.
In the present invention, in the measured particle size distribution, particles having a cumulative mass of 50% are the average particle size, and a particle size having a cumulative mass of 100% is the maximum particle size.
　本発明の一実施形態において疎水化球状シリカ微粉末は、顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子が、平均球形度０．８８以上であり、顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子の総数を１００%とした場合、球形度０．８５以下の粒子の個数割合が２０％以下、顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子の総数を１００%とした場合、０．８０以下の粒子の個数割合が１０％以下であることが好ましい。
　球形度が低い粒子は、ストラクチャー構造を有している場合や凝集体を形成している場合が多く、球形度が低くなるほどその傾向は顕著になる。顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子が、平均球形度０．８８以上であって、顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子の総数を１００%とした場合、球形度０．８５以下の粒子の個数割合が２０％以下、球形度０．８０以下の粒子の個数割合が１０％以下であれば、ストラクチャー構造粒子や凝集体が少なく、トナー外添剤として用いた際に、より優れた帯電安定性を発揮することが出来る。顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子の平均球形度は０．９０以上が更に好ましく、０．９２以上が最も好ましい。また、顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子の総数を１００%とした場合、球形度０．８５以下の粒子の個数割合が１５％以下、球形度０．８０以下の粒子の個数割合が８％以下が更に好ましく、球形度０．８５以下の粒子の個数割合が１０％以下、球形度０．８０以下の粒子の個数割合が６％以下が最も好ましい。 In one embodiment of the present invention, the hydrophobized spherical silica fine powder has particles having a projected area equivalent circle diameter of 0.100 μm or more measured by microscopy having an average sphericity of 0.88 or more, and a projected area equivalent circle diameter measured by microscopy of 0. When the total number of particles having a diameter of 100 μm or more is 100%, the number ratio of particles having a sphericity of 0.85 or less is 20% or less, and the total number of particles having a projected area equivalent circle diameter of 0.100 μm or more by microscopy is 100%. In this case, the number ratio of the particles of 0.80 or less is preferably 10% or less.
Particles with low sphericity often have a structure structure or form aggregates, and the tendency becomes more pronounced as the sphericity decreases. When particles having a projected area equivalent circle diameter of 0.100 μm or more measured by a microscopic method have an average sphericity of 0.88 or more and the total number of particles projected by a microscope projected area equivalent diameter of 0.100 μm or more is 100%, If the number ratio of particles having a sphericity of 0.85 or less is 20% or less and the number ratio of particles having a sphericity of 0.80 or less is 10% or less, there are few structure structure particles and aggregates, and the toner is used as an external toner additive. Better charging stability can be achieved. The average sphericity of particles having a projected area equivalent circle diameter of 0.100 μm or more measured by microscopy is more preferably 0.90 or more, and most preferably 0.92 or more. Further, when the total number of particles having a projected area equivalent circle diameter of 0.100 μm or more measured by microscopy is 100%, the number ratio of particles having a sphericity of 0.85 or less is 15% or less and the sphericity is 0.80 or less. The number ratio is more preferably 8% or less, the number ratio of particles having a sphericity of 0.85 or less is most preferably 10%, and the number ratio of particles having a sphericity of 0.80 or less is most preferably 6% or less.
　本発明の一実施形態において疎水化球状シリカ微粉末の球形度は、下記方法で測定することができる。疎水化球状シリカ微粉末をカーボンペーストで試料台に固定後、オスミウムコーティングを行い、日本電子社製走査型電子顕微鏡「ＪＳＭ－６３０１Ｆ型」で撮影した倍率５００００倍、解像度２０４８×１３５６ピクセルの画像をパソコンに取り込んだ。この画像を、マウンテック社製画像解析装置「ＭａｃＶｉｅｗ　Ｖｅｒ．４」に取り込み、粒子の投影面積（Ａ）と周囲長（ＰＭ）から球形度を測定した。周囲長（ＰＭ）に対応する真円の面積を（Ｂ）とすると、その粒子の球形度はＡ／Ｂとなるので、試料の周囲長（ＰＭ）と同一の周囲長を持つ真円を想定すると、ＰＭ＝２πｒ、Ｂ＝πｒ２であるから、Ｂ＝π×（ＰＭ／２π）２となり、個々の粒子の球形度は、球形度＝Ａ／Ｂ＝Ａ×４π／（ＰＭ）２となる。このようにして得られた任意の投影面積円相当径０．１００μｍ以上の粒子２００個の球形度を求め、その平均値を平均球形度とした。また、これらの粒子２００個中の球形度０．８５以下、あるいは０．８０以下の粒子個数からそれぞれの粒子個数割合を計算した。 In one embodiment of the present invention, the sphericity of the hydrophobized spherical silica fine powder can be measured by the following method. After fixing the hydrophobized spherical silica powder to the sample stage with carbon paste, osmium coating was performed, and an image taken with a scanning electron microscope “JSM-6301F type” manufactured by JEOL Ltd. with a magnification of 50000 times and a resolution of 2048 × 1356 pixels I imported it into my computer. This image was taken into an image analysis apparatus “MacView Ver. 4” manufactured by Mountec Co., Ltd., and the sphericity was measured from the projected area (A) and the perimeter (PM) of the particles. If the area of a perfect circle corresponding to the perimeter (PM) is (B), the sphericity of the particle is A / B, so a perfect circle having the same perimeter as the perimeter (PM) of the sample is assumed. Then, since PM = 2πr and B = πr 2 , B = π × (PM / 2π) 2 , and the sphericity of each particle is sphericity = A / B = A × 4π / (PM) 2 . Become. The sphericity of 200 particles having an arbitrary projected area equivalent circle diameter of 0.100 μm or more thus obtained was determined, and the average value was taken as the average sphericity. Further, the ratio of the number of each particle was calculated from the number of particles having a sphericity of 0.85 or less, or 0.80 or less in these 200 particles.
　本発明の一実施形態における球状シリカ微粉末の疎水化処理法について説明する。本発明者は、ヘキサメチルジシラザンで疎水化処理を行う前に、球状シリカ微粉末表面に予め水分を吸着させることでシラノール基が活性化し、ヘキサメチルジシラザンを球状シリカ微粉末表面に高反応率で結合させることが可能となり、疎水化球状シリカ微粉末の帯電安定性を向上させることが出来ることを見出した。本発明者は、さらに水分を吸着させる際、単に水を噴霧して吸着させるよりも、水蒸気の状態で、かつ特定の温度及び湿度条件で水分を吸着させることで、ヘキサメチルジシラザンを球状シリカ微粉末表面に高反応率で非常に均一に結合させることが可能となり、疎水化球状シリカ微粉末の帯電安定性を一層向上させることが出来ることが分かった。また、水分の影響による凝集の発生も著しく低下させることが可能となり、流動性向上に対しても効果的であることが分かった。 The method for hydrophobizing spherical silica fine powder in one embodiment of the present invention will be described. Prior to hydrophobizing with hexamethyldisilazane, the inventor activated silanol groups by preliminarily adsorbing moisture on the surface of the spherical silica fine powder, and highly reacted hexamethyldisilazane on the surface of the spherical silica fine powder. It has been found that the charging stability of the hydrophobized spherical silica fine powder can be improved. The present inventors further adsorbed hexamethyldisilazane into spherical silica by adsorbing moisture in the state of water vapor and under specific temperature and humidity conditions, rather than simply spraying and adsorbing water when adsorbing moisture. It was found that the surface of the fine powder could be bonded very uniformly with a high reaction rate, and the charging stability of the hydrophobized spherical silica fine powder could be further improved. In addition, it has been found that the occurrence of aggregation due to the influence of moisture can be remarkably reduced, and is effective in improving fluidity.
　本発明の一実施形態における疎水化球状シリカ微粉末の製造方法は、ヘキサメチルジシラザンで疎水化処理を行う前に、温度３５℃以上５５℃以下、絶対湿度４０ｇ／ｍ３以上１００ｇ／ｍ３以下の条件下で２４時間以上放置した球状シリカ微粉末を用いることが好ましい。ヘキサメチルジシラザンで疎水化処理する前に、球状シリカ微粉末を温度３５℃以上５５℃以下、絶対湿度４０ｇ／ｍ３以上１００ｇ／ｍ３以下の条件下で２４時間以上放置することで、球状シリカ微粉末表面に非常に均一に水分を存在させることが出来る。これにより、ヘキサメチルジシラザンを噴霧した際に、均一疎水化処理を行うことが可能となり、トナー外添剤として使用した際に、経時変化による帯電安定性を向上させることが出来る。温度３５℃未満、及び／又は絶対湿度４０ｇ／ｍ３未満であると、球状シリカ微粉末の表面に存在する水分量が少なくなるため、ヘキサメチルジシラザンで疎水化処理を行った際の均一疎水性が不十分となり、トナー外添剤として使用した際に、経時変化による帯電安定性を十分に向上させることが出来ない。放置時間が２４時間未満の場合も同様で、球状シリカ微粉末の表面に存在する水分量が少なくなるため好ましくない。一方、温度５５℃超、及び／又は絶対湿度１００ｇ／ｍ３超であると、球状シリカ微粉末同士に働く液架橋の作用により、球状シリカ微粉末が凝集してしまう。そのため、ヘキサメチルジシラザンで疎水化処理を行った際に、球状シリカ微粉末の凝集内部の疎水性が低下し、結果として経時変化による帯電安定性を十分に向上させることが出来ない。温度３７℃以上５３℃以下が更に好ましく、４０℃以上５０℃以下が最も好ましい。また、絶対湿度４５ｇ／ｍ３以上９０ｇ／ｍ３以下が更に好ましく、５０ｇ／ｍ３以上８０ｇ／ｍ３以下が最も好ましい。 In one embodiment of the present invention, the hydrophobized spherical silica fine powder is produced by a method of hydrophobizing with hexamethyldisilazane at a temperature of 35 ° C. to 55 ° C. and an absolute humidity of 40 g / m 3 to 100 g / m 3. It is preferable to use fine spherical silica powder that has been allowed to stand for 24 hours or more under the following conditions. Before hydrophobizing with hexamethyldisilazane, the spherical silica fine powder is allowed to stand for 24 hours or more under conditions of a temperature of 35 ° C. or more and 55 ° C. or less and an absolute humidity of 40 g / m 3 or more and 100 g / m 3 or less. Moisture can be present evenly on the surface of the silica fine powder. This makes it possible to perform a uniform hydrophobic treatment when spraying hexamethyldisilazane, and to improve the charging stability due to changes over time when used as an external toner additive. When the temperature is less than 35 ° C. and / or the absolute humidity is less than 40 g / m 3 , the amount of water present on the surface of the spherical silica fine powder is reduced, so that the uniform hydrophobicity when the hydrophobic treatment is performed with hexamethyldisilazane Therefore, when used as an external toner additive, the charging stability due to changes over time cannot be sufficiently improved. The same applies to the case where the standing time is less than 24 hours, which is not preferable because the amount of water present on the surface of the spherical silica fine powder is reduced. On the other hand, when the temperature is higher than 55 ° C. and / or the absolute humidity is higher than 100 g / m 3 , the spherical silica fine powder is agglomerated by the action of liquid crosslinking acting between the spherical silica fine powders. For this reason, when the hydrophobization treatment is performed with hexamethyldisilazane, the hydrophobicity inside the aggregate of the spherical silica fine powder is lowered, and as a result, the charging stability due to the change with time cannot be sufficiently improved. The temperature is more preferably 37 ° C. or more and 53 ° C. or less, and most preferably 40 ° C. or more and 50 ° C. or less. Further, more preferably absolute humidity 45 g / m 3 or more 90 g / m 3 or less, 50 g / m 3 or more 80 g / m 3 or less is most preferred.
　本発明の一実施形態における疎水化球状シリカ微粉末の製造方法は、上述の条件で水分を球状シリカ微粉末に均一に存在させた後に、球状シリカ微粉末１ｍ２当たり、４．０×１０－６ｍｏｌ以上１．５×１０－５ｍｏｌ以下のヘキサメチルジシラザンを噴霧することが好ましい。ヘキサメチルジシラザンの噴霧量が、球状シリカ微粉末１ｍ２当たり、４．０×１０－６ｍｏｌ未満であると、均一疎水性が不十分となり、トナー外添剤として使用した際に、経時変化による帯電安定性を十分に向上させることが出来ない。一方、１．５×１０－５ｍｏｌを超えると、疎水化球状シリカ微粉末が凝集してしまう結果、トナー樹脂表面の疎水化球状シリカ微粉末被覆率が低くなり、スペーサー効果が低下する問題がある。ヘキサメチルジシラザンの噴霧量は、球状シリカ微粉末１ｍ２当たり、５．５×１０－６ｍｏｌ以上１．４×１０－５ｍｏｌ以下が更に好ましく、７．０×１０－６ｍｏｌ以上１．３×１０－５ｍｏｌ以下が最も好ましい。 Method for producing a powder hydrophobic spherical silica fine powder in an embodiment of the present invention, after the water was evenly present in the powder spherical silica fine powder under the conditions described above, the spherical silica fine powder 1 m 2 per, 4.0 × 10 - It is preferable to spray 6 mol or more and 1.5 × 10 −5 mol or less of hexamethyldisilazane. When the spray amount of hexamethyldisilazane is less than 4.0 × 10 −6 mol per 1 m 2 of the spherical silica fine powder, the uniform hydrophobicity becomes insufficient and changes over time when used as an external toner additive. The charging stability due to cannot be sufficiently improved. On the other hand, when it exceeds 1.5 × 10 −5 mol, the hydrophobic spherical silica fine powder aggregates, resulting in a problem that the hydrophobic spherical silica fine powder coverage on the toner resin surface is lowered and the spacer effect is lowered. is there. The spray amount of hexamethyldisilazane is more preferably 5.5 × 10 −6 mol or more and 1.4 × 10 −5 mol or less, and 7.0 × 10 −6 mol or more per 1 m 2 of spherical silica fine powder. Most preferred is 3 × 10 −5 mol or less.
　ヘキサメチルジシラザンの噴霧法は、例えば、球状シリカ微粉末原料を浮遊させた状態で原液を噴霧する方法、又はヘキサメチルジシラザンを噴霧させた後にガス化させ球状シリカ微粉末に接触させる方法などがある。 The hexamethyldisilazane spraying method is, for example, a method of spraying the stock solution in a state where the spherical silica fine powder raw material is suspended, or a method of spraying hexamethyldisilazane and then gasifying and contacting the spherical silica fine powder. There is.
　本発明の一実施形態における疎水化球状シリカ微粉末の製造方法においては、球状シリカ微粉末原料に対してヘキサメチルジシラザンを単独で処理しても良いし、２種類以上の表面処理剤で処理しても良い。例えば、正帯電性付与の為、アミノシランカップリング剤と併用する場合は、まず、球状シリカ微粉末にアミノシラン処理を行った後に、本発明の一実施形態における疎水化処理方法を実施すれば良い。 In the method for producing hydrophobized spherical silica fine powder according to one embodiment of the present invention, hexamethyldisilazane may be treated alone with respect to the spherical silica fine powder raw material, or treated with two or more kinds of surface treatment agents. You may do it. For example, when the aminosilane coupling agent is used in combination with an aminosilane coupling agent for imparting positive chargeability, first, the aminosilane treatment is performed on the spherical silica fine powder, and then the hydrophobization treatment method in one embodiment of the present invention may be performed.
　本発明の一実施形態における疎水化球状シリカ微粉末は、疎水化度が５０％以上であることが好ましい。疎水化度が５０％未満では、高湿度環境下におけるトナーの帯電特性が悪化したり、トナー粒子同士が凝集して流動性が低下したりする。５５％以上が更に好ましく、６０％以上が最も好ましい。疎水化度は以下の方法により測定することができる。すなわち、イオン交換水５０ｍｌ、試料０．２ｇをビーカーに入れ、マグネティックスターラーで攪拌しながらビュレットからメタノールを滴下する。ビーカー内のメタノール濃度が増加するにつれ粉体は徐々に沈降していき、その全量が沈んだ終点におけるメタノールとイオン交換水の混合溶液中のメタノールの容量％を疎水化度（％）とする。 The hydrophobized spherical silica fine powder in one embodiment of the present invention preferably has a hydrophobization degree of 50% or more. If the degree of hydrophobicity is less than 50%, the charging characteristics of the toner in a high-humidity environment are deteriorated, or the toner particles are aggregated to decrease the fluidity. More preferably 55% or more, and most preferably 60% or more. The degree of hydrophobicity can be measured by the following method. That is, 50 ml of ion-exchanged water and 0.2 g of a sample are put in a beaker, and methanol is dropped from a burette while stirring with a magnetic stirrer. As the methanol concentration in the beaker increases, the powder gradually settles, and the volume% of methanol in the mixed solution of methanol and ion-exchanged water at the end point when the total amount of the powder is settled is defined as the degree of hydrophobicity (%).
　本発明の一実施形態における疎水化球状シリカ微粉末の製造方法に用いる球状シリカ微粉末は、本発明の水分量、球形度の疎水化球状シリカ微粉末を実現するために、金属シリコンの酸化反応で得られた球状シリカ微粉末を用いることが好ましい。
　球状シリカ微粉末の製造方法を例示すれば、金属シリコンを化学炎や電気炉等で形成された高温場に投じて酸化反応させながら球状化する方法（例えば特許第１５６８１６８号明細書）、金属シリコン粒子スラリーを火炎中に噴霧して酸化反応させながら球状化する方法（例えば特開２０００－２４７６２６号公報）などが挙げられる。 The spherical silica fine powder used in the method for producing a hydrophobized spherical silica fine powder in one embodiment of the present invention is obtained by oxidizing metal silicon in order to realize the hydrophobized spherical silica fine powder having the water content and sphericity of the present invention. It is preferable to use the spherical silica fine powder obtained in (1).
As an example of a method for producing spherical silica fine powder, a method in which metal silicon is spheroidized while being subjected to an oxidation reaction by being applied to a high temperature field formed by a chemical flame or an electric furnace (for example, Japanese Patent No. 1568168), metal silicon Examples thereof include a method in which a particle slurry is sprayed into a flame and spheroidized while undergoing an oxidation reaction (for example, JP-A-2000-247626).
　本発明の一実施形態における疎水化球状シリカ微粉末の製造方法に用いる球状シリカ微粉末は、水分量が０．４ｗｔ％以下であり、レーザー回折散乱式粒度分布測定機にて測定された平均粒子径が０．０７０μｍ以上０．１７０μｍ以下、最大粒子径が０．３００μｍ以下である球状シリカ微粉末を用いることが好ましい。球状シリカ微粉末の水分量を０．４ｗｔ％以下、平均粒子径を０．０７０μｍ以上０．１７０μｍ以下、最大粒子径を０．３００μｍ以下とすることで、本発明の一実施形態における疎水化球状シリカ微粉末の水分量０．５ｗｔ％以下、平均粒子径０．０８０μｍ以上０．２００μｍ以下、最大粒子径０．８００μｍ以下の実現が容易となる。 The spherical silica fine powder used in the method for producing a hydrophobized spherical silica fine powder in one embodiment of the present invention has a water content of 0.4 wt% or less, and an average particle measured by a laser diffraction scattering type particle size distribution analyzer. It is preferable to use a fine spherical silica powder having a diameter of 0.070 μm or more and 0.170 μm or less and a maximum particle diameter of 0.300 μm or less. The water content of the spherical silica fine powder is 0.4 wt% or less, the average particle size is 0.070 μm or more and 0.170 μm or less, and the maximum particle size is 0.300 μm or less, thereby making the hydrophobic spherical shape in one embodiment of the present invention. It becomes easy to realize a water content of silica fine powder of 0.5 wt% or less, an average particle size of 0.080 μm to 0.200 μm, and a maximum particle size of 0.800 μm or less.
　本発明の一実施形態における疎水化球状シリカ微粉末のトナーへの配合量は、通常、トナー１００質量部に対して、０．１～６質量部が好ましく、さらに好ましくは０．３～４質量部である。配合量が少なすぎると、トナーへの付着量が少なく十分なスペーサー効果が得られず、多すぎるとトナー表面から疎水化球状シリカ微粉末が脱離するおそれがある。 The amount of the hydrophobized spherical silica fine powder blended in the toner according to an embodiment of the present invention is usually preferably 0.1 to 6 parts by mass, more preferably 0.3 to 4 parts by mass with respect to 100 parts by mass of the toner. Part. If the blending amount is too small, the adhesion amount to the toner is small and a sufficient spacer effect cannot be obtained. If the blending amount is too large, the hydrophobic spherical silica fine powder may be detached from the toner surface.
　本発明の一実施形態における疎水化球状シリカ微粉末を含有するトナー外添剤のシリカ粉末には、本発明の一実施形態における疎水化球状シリカ微粉末が単独で使用されるものとは限らず、例えば、流動性付与効果の高い２００～５００ｍ２／ｇ程度の超微粉末シリカと併用して使用することもできる。 The silica powder of the toner external additive containing the hydrophobized spherical silica fine powder in one embodiment of the present invention is not limited to the use of the hydrophobized spherical silica fine powder in one embodiment of the present invention alone. For example, it can be used in combination with ultrafine powder silica of about 200 to 500 m 2 / g, which has a high fluidity-imparting effect.
　本発明の一実施形態における球状シリカ微粉末を含有するトナー外添剤が添加される静電荷像現像用トナーとしては、結着樹脂と着色剤を主成分として構成される公知のものが使用できる。また、必要に応じて帯電制御剤が添加されていてもよい。 As the electrostatic image developing toner to which the toner external additive containing the spherical silica fine powder in one embodiment of the present invention is added, a known toner composed mainly of a binder resin and a colorant can be used. . Moreover, the charge control agent may be added as needed.
　本発明の一実施形態における疎水化球状シリカ微粉末を含有するトナー外添剤が添加された静電荷像現像用トナーは、一成分現像剤として使用でき、また、それをキャリアと混合して二成分現像剤として使用することもできる。二成分現像剤として使用する場合においては、上記トナー外添剤は予めトナー粒子に添加せず、トナーとキャリアの混合時に添加してトナーの表面被覆を行ってもよい。キャリアとしては、鉄粉等、あるいはそれらの表面に樹脂コーティングされた公知のものが使用される。 The toner for developing an electrostatic image to which an external toner additive containing a hydrophobic spherical silica fine powder according to an embodiment of the present invention is added can be used as a one-component developer, and can be mixed with a carrier to form a two-component developer. It can also be used as a component developer. When used as a two-component developer, the toner external additive may not be added to the toner particles in advance, but may be added when the toner and the carrier are mixed to coat the surface of the toner. As the carrier, iron powder or the like, or a known one whose surface is resin-coated is used.
　以下、本発明について、実施例及び比較例により、更に詳細に説明する。なお、本発明はこれらに限定されるものではない。
　実施例１～１４　比較例１～１０
　球状シリカ微粉末は、燃焼炉の頂部に内炎と外炎が形成できる二重管構造のＬＰＧ－酸素混合型バーナーが設置され、下部に捕集系ラインが直結されてなる装置を用いて製造した。上記バーナーの中心部には更にスラリー噴霧用の二流体ノズルが設置され、その中心部から、金属シリコン粉末（平均粒径１０．５μｍ）と水からなるスラリー（金属シリコン濃度：１０～７０質量％）を２～３０Ｌ／Ｈｒのフィード量で噴射した。周囲からは酸素を供給した。火炎の形成は二重管バーナーの出口に数十個の細孔を設け、そこからＬＰＧと酸素の混合ガスを噴射することによって行った。また、球状シリカ微粉末の水分量を調整するために、炉体中部側面に１流体ノズルを取り付け、０～１０Ｌ／Ｈｒのフィード量で水を噴霧した。二流体ノズルから噴射され火炎を通過して生成した球状シリカ微粉末は、ブロワによって捕集ラインを空気輸送させ、バグフィルターで捕集した。なお、球状シリカ微粉末の粒子径及び球形度の調整を、スラリー濃度及びスラリーフィード量の調整により行った。また、水分量の調整を、水噴霧用のフィード量の調整により行った。 Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. The present invention is not limited to these.
Examples 1 to 14 Comparative Examples 1 to 10
Spherical silica fine powder is manufactured using a device in which an LPG-oxygen mixed burner with a double pipe structure capable of forming an inner flame and an outer flame is installed at the top of the combustion furnace, and a collection system line is directly connected to the lower part. did. A two-fluid nozzle for slurry spraying is further installed at the center of the burner, and a slurry (metal silicon concentration: 10 to 70% by mass) composed of metal silicon powder (average particle size 10.5 μm) and water is formed from the center. ) Was injected at a feed amount of 2 to 30 L / Hr. Oxygen was supplied from the surroundings. The formation of the flame was performed by providing several tens of pores at the outlet of the double tube burner and injecting a mixed gas of LPG and oxygen therefrom. In order to adjust the water content of the spherical silica fine powder, a one-fluid nozzle was attached to the side surface of the middle part of the furnace body, and water was sprayed at a feed amount of 0 to 10 L / Hr. Spherical silica fine powder generated from a two-fluid nozzle and passing through a flame was pneumatically transported through a collection line by a blower and collected by a bag filter. The particle diameter and sphericity of the spherical silica fine powder were adjusted by adjusting the slurry concentration and the slurry feed amount. The amount of water was adjusted by adjusting the amount of feed for water spray.
　それらを適宜配合し、各種の球状シリカ微粉末を得た。球状シリカ微粉末の水分量、平均粒子径、及び最大粒子径を表１に示す。得られた球状シリカ微粉末を、それぞれ恒温恒湿槽（日立アプライアンス社製「ＥＣ－４５ＭＨＨＰ」）に入れ、種々の条件で、槽内に放置した。槽内に放置した際の、温度、絶対湿度、時間を表１、表２、表３に示す。 These were blended appropriately to obtain various spherical silica fine powders. Table 1 shows the water content, average particle size, and maximum particle size of the fine spherical silica powder. The obtained spherical silica fine powders were respectively placed in a constant temperature and humidity chamber (“EC-45MHP” manufactured by Hitachi Appliances) and left in the bath under various conditions. Tables 1, 2, and 3 show the temperature, absolute humidity, and time when left in the tank.
　恒温恒湿槽から取り出したそれぞれの球状シリカ微粉末１００ｇを直ぐに流動層（中央化工機社製「振動流動層装置ＶＵＡ－１５型」）に仕込み、Ｎ２ガスで流動させたところにヘキサメチルジシラザン（信越化学工業社製「ＳＺ－３１」）を、種々の噴霧量で噴霧し、２０分間流動混合した。流動混合後、１３０℃に昇温し、窒素ガスを通気しながら生成したアンモニアを除去し、疎水化球状シリカ微粉末Ａ～Ｗを得た。また、単純に水噴霧を行って水分吸着をさせた後に、上記と同様の方法で疎水化処理を行い、疎水化球状シリカ微粉末Ｘを得た。ヘキサメチルジシラザンの噴霧量を表１、表２、表３に示す。また、疎水化球状シリカ微粉末Ａ～Ｗの粉体抵抗、水分量、タップ密度、レーザー回折散乱式粒度分布測定機にて測定された平均粒子径、最大粒子径、顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子の平均球形度、球形度０．８８以下の粒子個数割合、０．８５以下の粒子個数割合を表１、表２、表３に示す。なお、得られた疎水化球状シリカ微粉末の疎水化度はいずれも６５％以上であった。 100 g of each spherical silica fine powder taken out from the constant temperature and humidity chamber was immediately charged into a fluidized bed (Chuo Kakoki Co., Ltd. “vibrating fluidized bed apparatus VUA-15 type”) and fluidized with N 2 gas. Silazane (“SZ-31” manufactured by Shin-Etsu Chemical Co., Ltd.) was sprayed in various spray amounts and fluidly mixed for 20 minutes. After fluid mixing, the temperature was raised to 130 ° C., and ammonia formed while removing nitrogen gas was removed to obtain hydrophobized spherical silica fine powders A to W. In addition, after water was simply sprayed to adsorb moisture, hydrophobization treatment was performed in the same manner as above to obtain hydrophobized spherical silica fine powder X. The spray amounts of hexamethyldisilazane are shown in Table 1, Table 2, and Table 3. Also, powder resistance, water content, tap density, average particle diameter measured by laser diffraction / scattering particle size distribution analyzer, maximum particle diameter, and projected area circle by microscope method of hydrophobized spherical silica fine powders A to W Tables 1, 2 and 3 show the average sphericity of particles having a diameter of 0.100 μm or more, the number ratio of particles having a sphericity of 0.88 or less, and the number ratio of particles having a diameter of 0.85 or less. The hydrophobicity of the resulting hydrophobized spherical silica fine powder was 65% or more.
　疎水化球状シリカ微粉末Ａ～Ｗの、トナー外添剤としての特性を評価するために、圧縮度変化比率、安息角、帯電量、帯電保持比率、外添剤被覆率を以下の方法に従って測定した。それらの結果を表１、表２、表３に示す。 In order to evaluate the properties of hydrophobic spherical silica fine powders A to W as toner external additives, the compression ratio change ratio, angle of repose, charge amount, charge retention ratio, and external additive coverage were measured according to the following methods. did. The results are shown in Table 1, Table 2, and Table 3.
（１）圧縮度変化比率
　疎水化球状シリカ微粉末Ａ～Ｘ５ｇと、平均粒子径５μｍの架橋スチレン樹脂粉（綜研化学社製商品名「ＳＸ－５００Ｈ」）４９０ｇ、流動性付与のため市販のフュームドシリカ２００ｍ２／ｇ品５ｇをヘンシェルミキサー（三井三池化工機社製「ＦＭ－１０Ｂ型」）に入れ、１０００ｒｐｍで１分間混合し疑似トナーを作製した。この模擬トナーを、温度２５℃、相対湿度５５％の条件下で２４Ｈｒ静置後、パウダテスター（ホソカワミクロン社製「ＰＴ－Ｅ型」）を用いて圧縮度を評価した。圧縮度は下記式によって算出される。
　圧縮度＝（固め見掛け比重－ゆるみ見掛け比重）／固め見掛け比重×１００（％）
なお、ゆるみ見掛け比重は、１００ｍｌのカップに疑似トナーを入れ、タッピングをしない状態で測定した比重であり、固め見掛け比重は、１００ｍｌのカップに疑似トナーを入れ、１秒に１回の速さで１８０回タッピング後に測定した見掛け比重である。
　次に、ヘンシェルミキサーの混合時間を３分から３０分に変更して圧縮度測定を行い、圧縮度変化比率を下記式から算出した。
　圧縮度変化比率＝混合時間３０分の時の圧縮度／混合時間３分の時の圧縮度
　この圧縮度変化比率が１に近い、すなわち圧縮度の変化が小さいほど、スペーサー効果が良好であることを表す。 (1) Compressibility change ratio Hydrophobized spherical silica fine powder A to X 5 g, cross-linked styrene resin powder having an average particle size of 5 μm (trade name “SX-500H” manufactured by Soken Chemical Co., Ltd.), commercially available fume for imparting fluidity A silica toner of 200 m 2 / g 5 g was put into a Henschel mixer (“FM-10B type” manufactured by Mitsui Miike Chemical Co., Ltd.) and mixed at 1000 rpm for 1 minute to prepare a pseudo toner. The simulated toner was allowed to stand for 24 hours under conditions of a temperature of 25 ° C. and a relative humidity of 55%, and the degree of compression was evaluated using a powder tester (“PT-E type” manufactured by Hosokawa Micron). The degree of compression is calculated by the following formula.
Compressibility = (Fixed apparent specific gravity-Loose apparent specific gravity) / Fixed apparent specific gravity x 100 (%)
The loose apparent specific gravity is a specific gravity measured with a pseudo-toner placed in a 100 ml cup and without tapping. The solid apparent specific gravity is a pseudo-toner put into a 100 ml cup at a rate of once per second. The apparent specific gravity measured after tapping 180 times.
Next, the compression time was measured by changing the mixing time of the Henschel mixer from 3 minutes to 30 minutes, and the compression ratio change ratio was calculated from the following equation.
Compressibility change ratio = compression degree when mixing time is 30 minutes / compression degree when mixing time is 3 minutes The compressibility change ratio is closer to 1, that is, the smaller the change in the compression degree, the better the spacer effect is Represents.
（２）安息角
　疎水化球状シリカ微粉末Ａ～Ｘ１０ｇと、平均粒子径５μｍの架橋スチレン樹脂粉（綜研化学社製商品名「ＳＸ－５００Ｈ」）４９０ｇをヘンシェルミキサー（三井三池化工機社製「ＦＭ－１０Ｂ型」）に入れ、１０００ｒｐｍで１分間混合し疑似トナーを作製した。この模擬トナーを、温度２５℃、相対湿度５５％の条件下で２４Ｈｒ静置後、パウダテスター（ホソカワミクロン社製「ＰＴ－Ｅ型」）を用いて安息角を評価した。温度２５℃、相対湿度５５％の条件下で２４Ｈｒ静置させた模擬トナーを目開き７１０μｍの篩に乗せ、振動を与えながら、漏斗を通して直径８ｃｍの円形測定用テーブルに堆積させた。円錐状に形成される堆積状態が一定になるまで堆積させた後、分度器を用いて水平面に対する堆積粉の陵線の角度を安息角とした。この安息角の値が小さいほど、流動性が良好であることを示す。 (2) Angle of repose Hydrophobized spherical silica fine powders A to X10 g and 490 g of a crosslinked styrene resin powder having an average particle size of 5 μm (trade name “SX-500H” manufactured by Soken Chemical Co., Ltd.) were added to a Henschel mixer (Mitsui Miike Chemical Co., Ltd. “ FM-10B type ") and mixed at 1000 rpm for 1 minute to prepare a pseudo toner. The simulated toner was allowed to stand for 24 hours at a temperature of 25 ° C. and a relative humidity of 55%, and then the angle of repose was evaluated using a powder tester (“PT-E type” manufactured by Hosokawa Micron). A simulated toner that was allowed to stand for 24 hours under the conditions of a temperature of 25 ° C. and a relative humidity of 55% was placed on a sieve having a mesh opening of 710 μm and deposited on a circular measuring table having a diameter of 8 cm through a funnel while applying vibration. After deposition until the deposition state formed in a conical shape became constant, the angle of the line of the deposited powder with respect to the horizontal plane was defined as the angle of repose using a protractor. It shows that fluidity | liquidity is so favorable that the value of this angle of repose is small.
（３）帯電量
　疎水化球状シリカ微粉末Ａ～Ｘ１５ｇと、平均粒子径５μｍの架橋スチレン樹脂粉（綜研化学社製商品名「ＳＸ－５００Ｈ」）４８５ｇをヘンシェルミキサー（三井三池化工機社製「ＦＭ－１０Ｂ型」）に入れ、１０００ｒｐｍで１分間混合し疑似トナーを作製した。この疑似トナーを、温度２５℃、相対湿度５５％の条件下で２４Ｈｒ静置した後、ブローオフ帯電量を以下の手法で測定した。模擬トナー０．２０ｇと、キャリアとして負帯電極性トナー用標準キャリア（日本画像学会より頒布「Ｎ－０１」）３．８０ｇを１００ｍｌポリエチレン製容器に入れ、アサヒ理化製作所社製小型ボール回転架台「ＡＶ－１型」を用い、１秒間に１回転の速度で回転振とうさせた。振とう５分後、この模擬トナーとキャリアの混合物０．３０ｇを用いて吸引分離式帯電量測定器（三協パイオテク社製「セパソフトＳＴＣ－１」）により、ブローオフ帯電量を測定した。吸引時間は３分間、吸引圧力は４．０ｋＰａとし、模擬トナーとキャリアの分離に用いるスクリーンには目開き３２μｍの金網を使用した。
　このブローオフ帯電量のマイナスの値が大きいほど帯電量が大きいことを表す。 (3) Charge amount Hydrophobized spherical silica fine powders A to X 15 g and 485 g of a crosslinked styrene resin powder having an average particle size of 5 μm (trade name “SX-500H” manufactured by Soken Chemical Co., Ltd.) were added to a Henschel mixer (manufactured by Mitsui Miike Chemical Co., Ltd.). FM-10B type ") and mixed at 1000 rpm for 1 minute to prepare a pseudo toner. The pseudo toner was allowed to stand for 24 hours under conditions of a temperature of 25 ° C. and a relative humidity of 55%, and then the blow-off charge amount was measured by the following method. 0.20 g of the simulated toner and 3.80 g of a standard carrier for negatively charged polarity toner (distributed by the Imaging Society of Japan “N-01”) as a carrier are placed in a 100 ml polyethylene container, and a small ball rotating base “AV” manufactured by Asahi Rika Seisakusho -1 type "was used and shaken at a speed of 1 revolution per second. After 5 minutes of shaking, the blow-off charge amount was measured with 0.30 g of the mixture of the simulated toner and carrier using a suction separation type charge amount measuring device (“Sepasoft STC-1” manufactured by Sankyo Piotech Co., Ltd.). The suction time was 3 minutes, the suction pressure was 4.0 kPa, and a screen of 32 μm mesh was used for the screen used for separating the simulated toner and the carrier.
The larger the negative value of the blow-off charge amount, the larger the charge amount.
（４）帯電保持比率
　ボールミル回転架台での回転振とう時間を５分から１２０分に変更して、ブローオフ帯電量測定を行い、下記式から帯電保持比率を算出した。
　帯電保持比率＝振とう１２０分後のブローオフ帯電量／振とう５分後のブローオフ帯電量
この帯電保持比率の値が１に近い、すなわち、帯電量の変化が少ないほど、帯電の経時安定性が良好であることを表す。 (4) Charge retention ratio The rotation shaking time on the ball mill rotary mount was changed from 5 minutes to 120 minutes, the blow-off charge amount was measured, and the charge retention ratio was calculated from the following formula.
Charge holding ratio = Blow-off charge amount after 120 minutes of shaking / Blow-off charge amount after 5 minutes of shaking The value of this charge holding ratio is closer to 1, that is, the smaller the change in the charge amount, the more stable the charge is with time. Represents good.
　（５）外添剤被覆率
　帯電保持比率を測定する際に調製した模擬トナーをカーボンペーストで試料台に固定後、オスミウムコーティングを行い、電子顕微鏡（日本電子社製「ＪＳＭ－６３０１型」）観察を行った。倍率１５０００倍の画像をパソコンに取り込み、画像解析装置（マウンテック社製「ＭａｃＶｉｅｗ」）を用いて架橋スチレン樹脂粉の投影面積と球状シリカ微粉末の投影面積を測定し、下記式から疑似トナー１個当たりの外添剤被覆率を求めた。
　疑似トナー１個当たりの外添剤被覆率＝（１個の架橋スチレン樹脂粉表面に付着する球状シリカ微粉末の合計投影面積／１個の架橋スチレン樹脂粉の投影面積）×１００（％）
　疑似トナー２０個について外添剤被覆率を計算し、その平均値を平均外添剤被覆率とした。 (5) External additive coverage The simulated toner prepared when measuring the charge retention ratio was fixed to the sample stage with carbon paste, then coated with osmium, and observed with an electron microscope (“JSM-6301” manufactured by JEOL Ltd.) Went. An image with a magnification of 15000 is taken into a personal computer, and the projected area of the crosslinked styrene resin powder and the spherical silica fine powder are measured using an image analyzer (“MacView” manufactured by Mountec Co., Ltd.). The external additive coverage per unit was determined.
External additive coverage per pseudo toner = (total projected area of spherical silica fine powder adhering to the surface of one crosslinked styrene resin powder / projected area of one crosslinked styrene resin powder) × 100 (%)
The external additive coverage was calculated for 20 pseudo toners, and the average value was taken as the average external additive coverage.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
　
Figure JPOXMLDOC01-appb-T000003
　
　実施例と比較例の対比から明らかなように、本発明によれば、帯電安定性、流動性、スペーサー効果、帯電量に優れたトナー外添剤を提供することができる。また、前記トナー外添剤に好適な疎水化球状シリカ微粉末を提供することができる。 As is clear from the comparison between the examples and the comparative examples, according to the present invention, it is possible to provide an external toner additive excellent in charging stability, fluidity, spacer effect, and charge amount. In addition, a hydrophobic spherical silica fine powder suitable for the toner external additive can be provided.
　本発明の疎水化球状シリカ微粉末は、複写機やレーザープリンター等に使用される電子写真用トナーの外添剤として利用される。

　 The hydrophobized spherical silica fine powder of the present invention is used as an external additive for electrophotographic toners used in copying machines, laser printers and the like.

Claims (6)

  1. 　粉体抵抗が１．０×１０１３Ω・ｃｍ以上３．０×１０１４Ω・ｃｍ以下であり、水分量が０．５ｗｔ％以下であり、タップ密度が０．１０ｇ／ｃｍ３以上０．４０ｇ／ｃｍ３以下であることを特徴とする疎水化球状シリカ微粉末。 The powder resistance is 1.0 × 10 13 Ω · cm or more and 3.0 × 10 14 Ω · cm or less, the water content is 0.5 wt% or less, and the tap density is 0.10 g / cm 3 or more. Hydrophobized spherical silica fine powder characterized by being 40 g / cm 3 or less.
  2. 　前記疎水化球状シリカ微粉末のレーザー回折散乱式粒度分布測定機にて測定された平均粒子径が０．０８０μｍ以上０．２００μｍ以下であり、前記疎水化球状シリカ微粉末の最大粒子径が０．８００μｍ以下であることを特徴とする請求項１に記載の疎水化球状シリカ微粉末。 The average particle diameter of the hydrophobized spherical silica fine powder measured by a laser diffraction / scattering particle size distribution analyzer is 0.080 μm or more and 0.200 μm or less, and the maximum particle diameter of the hydrophobized spherical silica fine powder is 0.00. The hydrophobized spherical silica fine powder according to claim 1, which is 800 μm or less.
  3. 　前記疎水化球状シリカ微粉末において顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子は、平均球形度０．８８以上であり、
    　前記顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子の総数を１００%とした場合、球形度０．８５以下の粒子の個数割合が２０％以下であり、
    　前記顕微鏡法による投影面積円相当径０．１００μｍ以上の粒子の総数を１００%とした場合、球形度０．８０以下の粒子の個数割合が１０％以下であることを特徴とする請求項１又は２に記載の疎水化球状シリカ微粉末。     Particles having a projected area equivalent circle diameter of 0.100 μm or more in the hydrophobized spherical silica fine powder have an average sphericity of 0.88 or more,
    When the total number of particles having a projected area equivalent circle diameter of 0.100 μm or more by the microscopic method is 100%, the number ratio of particles having a sphericity of 0.85 or less is 20% or less,
    The number ratio of particles having a sphericity of 0.80 or less is 10% or less when the total number of particles having a projected area equivalent circle diameter of 0.100 μm or more by the microscopy is 100%. 2. Hydrophobized spherical silica fine powder according to 2.
  4. 　温度３５℃以上５５℃以下、絶対湿度４０ｇ／ｍ３以上１００ｇ／ｍ３以下の条件下で２４時間以上放置した球状シリカ微粉末に、前記球状シリカ粉末１ｍ２当たり、４．０×１０－６ｍｏｌ以上１．５×１０－５ｍｏｌ以下のヘキサメチルジシラザンを噴霧することを特徴とする請求項１から３のいずれか１項に記載の疎水化球状シリカ微粉末の製造方法。 A spherical silica fine powder left at a temperature of 35 ° C. to 55 ° C. and an absolute humidity of 40 g / m 3 to 100 g / m 3 for 24 hours or more is applied to 4.0 × 10 −6 per 1 m 2 of the spherical silica powder. The method for producing a hydrophobized spherical silica fine powder according to any one of claims 1 to 3, wherein hexamethyldisilazane is sprayed in an amount of not less than mol and not more than 1.5 × 10 -5 mol.
  5. 　前記球状シリカ微粉末は、水分量が０．４ｗｔ％以下であり、レーザー回折散乱式粒度分布測定機にて測定された平均粒子径が０．０７０μｍ以上０．１７０μｍ以下であり、最大粒子径が０．３００μｍ以下であることを特徴とする請求項４に記載の疎水化球状シリカ微粉末の製造方法。 The spherical silica fine powder has a water content of 0.4 wt% or less, an average particle size of 0.070 μm or more and 0.170 μm or less measured by a laser diffraction / scattering particle size distribution analyzer, and a maximum particle size of It is 0.300 micrometer or less, The manufacturing method of the hydrophobic spherical silica fine powder of Claim 4 characterized by the above-mentioned.
  6. 　請求項１から３のいずれか１項に記載の疎水化球状シリカ微粉末を含有することを特徴とする静電荷像現像用トナー外添剤。 A toner external additive for developing an electrostatic charge image, comprising the hydrophobized spherical silica fine powder according to any one of claims 1 to 3.
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