JP2009263152A - Particle and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a particle which makes silica into a core material, has a high negative charge amount and a markedly reduced hygroscopicity, and therefore is excellent in charge retaining performance and stability of charge characteristics, and its manufacturing method. <P>SOLUTION: The particle is composed of silica and a surface layer which is formed on the surface of silica and contains a fluorine-containing polymer, where the specific surface area ratio (Ss/Ss<SB>0</SB>) of the specific surface area Ss of silica to the theoretical surface area Ss<SB>0</SB>is 2 or less, the frictional charge polarity of the particle is negative and the absolute value of frictional charge amount is 50 μc/g or more. The particle is preferably manufactured by a method including a process for producing silica having a specific surface area ratio (Ss/Ss<SB>0</SB>) of 2 or less by calcining a silica particle obtained by a hydrolysis-condensation reaction of an alkoxysilane at 650-1,180°C and a process for forming a surface layer containing a fluorine-containing polymer on the surface of the silica. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention is suitable for use as a charge control agent such as an external additive for toners, has a form having a specific surface layer with a specific silica as a core material, and a method for producing the particle It is about.

Silica particles are used as fillers for semiconductor encapsulating resins and as external additives for toners for equipment such as copiers and printers. For example, when silica particles are used as an external additive for toner, it is required that the triboelectric charge amount is high and the charge holding performance is excellent.
In Patent Documents 1 to 3, silica particles produced by a dry method such as a flame method or silica particles produced by a wet method such as an alkoxide method are used as silica particles for an external additive for toner. Silica particles obtained by treatment are disclosed. For example, Patent Document 1 discloses that particles obtained by hydrolysis and condensation reaction of two types of alkoxysilanes are surface-treated with two types of silane coupling agents, so that the charge amount with a particle diameter of 0.01 to 5 μm is −100. ~ -300 μc / g silica particles are obtained, Patent Document 2 discloses silica fine powder hydrophobized with a silane coupling agent and / or silicone oil, and Patent Document 3 describes the amount of surface silanol groups. Silica particles hydrophobized by bringing fine silica below a predetermined value into contact with hexamethyldisilazane are disclosed. The silica particles obtained in these patent documents have a problem in that the charge retention performance is not sufficient, and the charging characteristics deteriorate due to moisture absorption during storage.
Further, Patent Document 4 and Patent Document 5 disclose silica particles obtained by calcining alkoxide-based silica at a high temperature. However, surface treatment is disclosed before or after the calcining treatment. The silica particles obtained were not sufficiently charged. Therefore, it is desired to realize silica particles having a high triboelectric charge amount, excellent charge holding performance, and no deterioration in charging characteristics.

JP-A-2005-15251 JP 2004-14532 A Japanese Patent Laid-Open No. 7-10524 JP 2003-165718 A JP 2006-325990 A

  In view of the above circumstances, the present invention provides particles that are excellent in charge retention performance and stability of charging characteristics because silica is a core material, the negative charge amount is high, and the hygroscopicity is remarkably reduced. Objective. The present invention also provides a method for producing particles having a high negative charge amount and a significantly reduced hygroscopic property while using silica as a core material, and having excellent charge retention performance and stability of charge characteristics. The purpose.

As a result of intensive studies on particles suitable as a charge control agent having a high negative charge amount and a suppressed hygroscopicity, the present inventors form a surface layer essentially comprising a predetermined polymer on the surface of silica. As a result, the present inventors have found that the above problems can be solved and completed the present invention.
That is, the particle according to the present invention is a particle composed of a surface layer containing silica and a fluorine-containing polymer formed on the surface thereof, and the theoretical surface area Ss of the specific surface area Ss of silica represented by the following formula (1). _The specific surface area ratio (Ss / Ss ₀ ) to ₀ is 2 or less, and the absolute value of the triboelectric charge amount of the particles is 50 μc / g or more.
Ss ₀ (m ² / g) = 6 / (ρ × d) (1)
ρ: True specific gravity of silica
d: Average primary particle diameter of silica (μm)
In the particles, the ratio of the surface layer is preferably 0.1 to 100 mg / m 2 per unit specific surface area of the particles, and the fluorine content in the surface layer is 100% by mass of the surface layer. The content is preferably 1 to 50% by mass. The fluorine-containing polymer preferably further has an alkyl group having 6 to 20 carbon atoms. The fluorine-containing polymer is preferably a fluorine-containing vinyl polymer. Moreover, it is preferable that the water content of the particles after standing for 24 hours in an atmosphere of 30 ° C. and 90% relative humidity is 0.3% or less. Particles having these conditions are particles having a further excellent triboelectric charge amount.
Moreover, the isolated silanol group content of the silica is preferably 0.01 to 5 mmol / g. The core silica is identified as having very few surface pores and having a predetermined isolated silanol group content, so that the hygroscopicity of the particles of the present invention is remarkably suppressed. And the adhesion of the surface layer containing the fluorine-containing polymer to silica is high.
Moreover, it is preferable that the said silica consists of a single particle. When the core is made of single-particle silica, the triboelectric charge amount of the particles is excellent. Moreover, it is preferable that the silica particle which a silica particle which consists of a hydrolysis-condensation product of an alkoxysilane baked at 650-1150 degreeC. The particles having silica as a core obtained by such a production method are suppressed in hygroscopicity.
In addition, in the particles of the present invention, it is preferable that the silica is surface-treated with a polymerizable silane compound because the friction charging characteristics are further improved.

The present invention also provides a suitable method for producing the particles of the present invention described above. That is, the production method includes a step of producing a silica satisfying a specific surface area ratio (S / Ss ₀ ) of a specific surface area Ss to a theoretical surface area Ss ₀ represented by the following formula (2) of 2 or less; And a step of forming a surface layer containing the containing polymer.
Ss ₀ (m ² / g) = 6 / (ρ × d) (2)
ρ: True specific gravity of silica d: Average primary particle diameter of silica (μm)
Furthermore, the step of producing the silica includes the step (1) of producing silica particles by hydrolyzing and condensing alkoxysilane, and producing the silica by firing the silica particles in a temperature range of 650 to 1180 ° C. It is preferable that the process (2) to include is included.

  Since the particle | grains which concern on this invention are particles which consist of a surface layer containing the specific silica and the fluorine-containing polymer formed in the surface, it has the characteristics that moisture absorption is suppressed and the triboelectric charge amount is high.

(particle)
The particle | grains which concern on this invention are particles which consist of a surface layer containing the specific silica and the fluorine-containing polymer formed in the surface.
The particles of the present invention are characterized in that the silica as the core material satisfies a specific surface area ratio (S / Ss ₀ ) of 2 or less with respect to the theoretical surface area Ss _{0 represented} by the following formula (1).
Ss ₀ (m ² / g) = 6 / (ρ × d) (1)
ρ: True specific gravity of silica d: Average primary particle diameter of silica (μm)
In addition, the particle of the present invention is characterized in that the surface is formed by forming a surface layer containing a fluorine-containing polymer on the surface of the silica. Furthermore, the particle of the present invention has the first and second characteristics, and the third characteristic is that the absolute value of the triboelectric charge amount of the particle is 50 μc / g or more.

The first feature means that the silica according to the present invention has substantially no pores on the surface, or even a small amount, so that moisture is extremely difficult to condense, Saturated hygroscopicity is extremely suppressed. As a result, the adhesion between the silica and the surface layer containing the fluorine-containing polymer provided on the surface thereof is excellent, and the hygroscopicity of the particles of the present invention is suppressed. It is high and has excellent charge holding performance. Further, as a result of the first feature, the surface of the silica is excellent in smoothness, so that the surface layer containing the fluorine-containing polymer is uniformly formed, and therefore the charging characteristics are excellent. It is also possible.
It is preferable that the particles of the present invention have a very small amount even if there are no pores on the surface, and are substantially nonporous. Specifically, the specific surface area (Sp) of the particles of the present invention is such that the specific surface area ratio (Sp / Sp ₀ ) with respect to the theoretical surface area Sp _{0 represented} by the following formula (3) satisfies 2 or less. preferable. More preferably, the specific surface area ratio (Sp / Sp ₀ ) satisfies 1.5 or less, more preferably 1.3 or less, and particularly preferably 1.2 or less. The specific surface area ratio (Sp / Sp ₀ ) preferably satisfies 0.6 or more, and more preferably 0.8 or more. When the specific surface area ratio (Sp / Sp ₀ ) of the particles of the present invention is in the above range, hygroscopicity is particularly suppressed. Specific surface area (Sp) E. T.A. The value measured by the method can be preferably adopted.

Sp ₀ (m ² / g) = 6 / (ρ × d) (3)
ρ: True specific gravity of particles d: Average primary particle diameter of particles (μm)
The particles of the present invention preferably have a water content of 0.3% or less after being left for 24 hours in an atmosphere having a temperature of 30 ° C. and a relative humidity of 90%. This means that the saturated moisture absorption of the particles of the present invention is 0.3% or less. The water content is more preferably 0.2% or less, and particularly preferably 0.1% or less. The smaller the water content, the higher the negative charge amount and the better the charge retention performance. The water content of the particles can be measured by the Karl Fischer method.

  The particles of the present invention are preferably particles that are negatively charged by friction. Further, the absolute value of the triboelectric charge amount is 50 μc / g or more. The absolute value of the charge amount is preferably 60 μc / g or more, more preferably 80 μc / g or more, and further preferably 100 μc / g or more as a charge control agent. The upper limit of the absolute value is preferably 200 μc / g. The triboelectric charge amount can be measured using a blow-off charge measuring machine (TB-200 / manufactured by Kyocera Chemical Co.).

  The particles of the present invention are preferably excellent in hydrophobicity because of excellent triboelectric chargeability. The particles of the present invention are excellent in hydrophobicity because a surface layer containing a fluorine-containing polymer is formed on the surface. The degree of hydrophobicity as a measure of hydrophobicity is preferably 60 to 100, more preferably 70 to 95. Especially preferably, it is 70-80. The degree of hydrophobicity is determined by gradually introducing methanol into the water after the particles float on the surface of 50 cc of water until the particles sink. That is, the percentage (%) of the methanol introduction capacity in the total volume of water and the volume of methanol introduced before the particles sink is the degree of hydrophobicity.

  The core constituting the particles of the present invention is preferably made of a single granular silica. That is, the silica as the core material is preferably in the form of primary particles and the surface is coated with a surface layer containing a fluorine-containing polymer. When silica is a secondary aggregate of primary particles or a fusion of primary particles, the particles of the present invention on which a surface layer containing a fluorine-containing polymer is formed may not exhibit a sufficient triboelectric charge amount. is there. In the particles of the present invention, whether or not the core is made of a single silica can be confirmed by directly observing the particles or by observing the cut surface of the particles with a transmission electron microscope.

Moreover, it is preferable that the particles of the present invention are dispersed as primary particles without secondary aggregation or sticking. If they are aggregated, when used as an external additive or a charging material for toner, fluidity may be insufficient, or a sufficient triboelectric charge may not be obtained. In the particles of the present invention, whether the particles are dispersed or aggregated with the primary particles can be confirmed by observing the particles with a transmission electron microscope or a scanning electron microscope.
The lower limit of the average primary particle diameter of the particles of the present invention is preferably 0.01 μm, more preferably 0.1 μm, and even more preferably 0.15 μm. The upper limit is preferably 3 μm, more preferably 2 μm, more preferably 1 μm, and particularly preferably 0.4 μm. Further, the coefficient of variation of the primary particle diameter of the particles is preferably 20% or less, more preferably 10% or less, and particularly preferably 5% or less.
The average value of the primary particle diameter of the particles can be determined by measuring the diameter of, for example, 50 to 100 particles from the electron microscope image and calculating the arithmetic average value based on the number. The variation coefficient of the primary particle diameter of the particles is calculated by the following formula. In addition, the standard deviation of a particle diameter means the arithmetic standard deviation of the particle size distribution of the number reference | standard obtained by measuring the diameter of 50-100 particles from an electron microscope image, for example.

Coefficient of variation (%) = (standard deviation of primary particle size / average value of primary particle size) × 100
The shape of the particles of the present invention is preferably substantially spherical. The ratio of the longest diameter to the shortest diameter of the particles is preferably 0.90 or more, more preferably 0.92 or more, more preferably 0.95 or more, and particularly preferably 0.98 or more. If there is an angular portion, the charged charge is liable to leak and the charge holding performance may be reduced. The shape of the particles can be confirmed by observing with a scanning electron microscope or a transmission electron microscope.
The dispersion average particle size of the particles of the present invention is not particularly limited, but the ratio of the dispersion average particle size to the primary particle size average value is preferably close to 1. Specifically, it is preferably 10 or less, more preferably 5 or less, more preferably 2 or less, and particularly preferably 1.5 or less. The lower limit of the dispersion average particle diameter of the particles of the present invention is preferably 0.01 μm, more preferably 0.05 μm, and even more preferably 0.15 μm. The upper limit is preferably 5 μm, more preferably 2 μm, more preferably 1 μm, and particularly preferably 0.4 μm. The dispersion average particle size of the particles means an arithmetic average value of a volume-based particle size distribution obtained by measurement with a laser diffraction / scattering particle size distribution measuring device (LA-920 manufactured by Horiba, Ltd.).

  The coefficient of variation of the particle diameter of the particles of the present invention is not particularly limited, but is preferably 50% or less, more preferably 30% or less, and particularly preferably 20% or less. The variation coefficient of the particle diameter of the particles is calculated by the following formula. In addition, the standard deviation of a particle diameter means the arithmetic standard deviation of the volume reference | standard particle size distribution obtained by measuring with the laser diffraction / scattering type particle size distribution measuring apparatus (LA-920 by Horiba, Ltd.).

Coefficient of variation (%) = standard deviation of particle diameter / dispersion average particle diameter * 100
In the particles of the present invention, the silica is coated with a surface layer containing a fluorine-containing polymer. The content of the fluorine-containing polymer in the surface layer is preferably 60% by mass or more, more preferably 80% by mass or more, more preferably 95% by mass or more, and particularly preferably, the surface layer is composed only of the fluorine-containing polymer. It is a form. If the content of the fluorine-containing polymer is less than 60% by mass, the effect of introducing the fluorine-containing polymer on the surface, that is, the charge amount may not be sufficient.
The charging characteristics of the particles are also affected by the ratio of the surface layer and the film thickness.
The content of the surface layer is preferably from 0.1 to 100 mg / m 2 per unit surface area of the particles in view of a high absolute value of the charge amount. More preferably, it is 0.5-80 mg / m2, More preferably, it is 1-20 g / m2, Especially 1-10 mg / m2. The surface layer is preferably a thin film having a thickness of 200 nm or less. By controlling the amount of the surface layer in the above extremely low range and the thin film thickness, surprisingly, particles having a particularly high negative charge amount can be obtained.
Moreover, although the fluorine content in the said surface layer is not specifically limited, It is preferable that it is 0.02-20 mass% with respect to 100 mass% of surface layers. More preferably, it is 0.1-10 mass%, More preferably, it is 0.25-5 mass%, Most preferably, it is 0.5-2.0 mass%. If the fluorine content in the surface layer is less than 0.02% by mass, the frictional charge holding performance may not be sufficient, and if it exceeds 20% by mass, it may be difficult to handle.
The silica that is the core in the particles of the present invention may or may not contain fluorine, and the same applies to the surface treatment agent described later. Therefore, the fluorine content in the particles of the present invention is influenced by the average particle diameter, the fluorine content in the surface layer, and the content in the surface layer particles. And in the range of 0.1 to 5% by mass.
The composition of the fluorine-containing polymer according to the present invention is not particularly limited, but the fluorine content in the fluorine-containing polymer is preferably 1 to 50% by mass with respect to 100% by mass of the polymer. More preferably, it is 5-40 mass%, Most preferably, it is 10-30 mass%. Further, if the fluorine content in the surface layer is less than 1% by mass, the frictional charge holding performance may not be sufficient, and if it exceeds 50% by mass, handling may be difficult.
The form in which fluorine is present is not particularly limited, but the form formed by covalent bonding to the carbon atoms constituting the polymer is preferable in that the triboelectric charge characteristics of the particles having the surface layer containing the fluorine-containing polymer are excellent. A form in which a fluorine atom is bonded to a carbon atom constituting an alkyl group, an aryl group, an aralkyl group or an alkylene group is further preferred. The form of a fluoroalkyl group is more preferred.
The fluorine-containing polymer preferably further has an alkyl group having 6 to 20 carbon atoms, an aryl group, or an aralkyl group (hereinafter referred to as a hydrophobic hydrocarbon group). Among them, an alkyl group having 6 to 20 carbon atoms is preferable, and a cycloalkyl group is particularly preferable.
Examples of the aryl group include a phenyl group, a tolyl group, and a 0-xylyl group. Examples of the aralkyl group include a benzyl group, a methylbenzyl group, a phenethyl group, a methylphenethyl group, a phenylbenzyl group, and a naphthylmethyl group. Examples of the alkyl group having 6 to 20 carbon atoms include linear or branched alkyl groups such as 1-hexyl group, 1-octyl group, 2-ethylexyl group, lauryl group, myristyl group and stearyl group; cycloalkyl such as cyclohexyl group The group is preferably exemplified.
The structure of the fluorine-containing polymer is not particularly limited, but a polymer having a C—C bond as a main chain is preferable, and a fluorine-containing vinyl polymer is more preferable. The fluorine-containing vinyl polymer is preferably a fluorine-containing vinyl polymer obtained by radical polymerization of a vinyl monomer essentially containing a fluorine-containing vinyl monomer. Among these, those obtained by copolymerizing a vinyl monomer essentially comprising a fluorine-containing vinyl monomer and the vinyl monomer having a hydrophobic hydrocarbon group are preferable.
Examples of the fluorine-containing vinyl monomer include 1H, 1H, 2H, 2H-heptadecafluorodecyl methacrylate, 1H, 1H, 5H-octafluoropentyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2,2,2-trifluoroethyl methacrylate, 1H, 1H, 2H, 2H-heptadecafluorodecyl acrylate, 1H, 1H, 5H-octafluoropentyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 2 , 2,2-trifluoroethyl acrylate, perfluorooctylethyl methacrylate, perfluorooctylethyl acrylate and other fluorine-containing (meth) acrylic monomers, and perfluorooctylethyl methacrylate is preferred.
Examples of the vinyl monomer having a hydrophobic hydrocarbon group include hexyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, stearyl acrylate, cyclohexyl acrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, and methacrylic acid. Hydrophobic hydrocarbon group-containing (meth) acrylic monomers such as acid dodecyl, stearyl methacrylate, cyclohexyl methacrylate; styrene, o-methylstyrene, p-tertiarybutylstyrene, p-phenylstyrene, o-chloro And hydrophobic hydrocarbon group-containing styrenic monomers such as aromatic divinyl compounds such as styrene, divinylbenzene, divinylnaphthalene and derivatives thereof. Of these, a hydrophobic hydrocarbon group-containing (meth) acrylic monomer is preferred.
Other monomers that can be copolymerized with the above preferred monomers are not particularly limited, but include acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, pentyl acrylate, methacrylic acid. Examples include acid, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, pentyl methacrylate and the like.
In order to improve the adhesion to silica, it is also preferable to use a polymerizable silane compound having an alkoxysilyl group as a monomer component. Examples of the polymerizable silane compound having an alkoxysilyl group include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane. Vinyltrimethoxysilane, vinyltriethoxysilane and the like.
The fluorine-containing vinyl polymer is usually obtained by copolymerizing a monomer component essentially containing a fluorine-containing vinyl monomer in the presence of a polymerization initiator. For example, in addition to solution polymerization in which polymerization is performed by heating in an organic solvent capable of dissolving a monomer such as toluene in the presence of a conventionally known peroxide-based initiator or azo-based initiator, dispersion polymerization, suspension, It can be prepared by a conventionally known polymerization method such as turbid polymerization.

The ratio of the fluorine-containing vinyl monomer in the fluorine-containing vinyl polymer is not particularly limited,
The ratio of the fluorine-containing vinyl monomer to the total monomer amount of 100% by mass is preferably in the range of 10 to 80% by mass, more preferably in the range of 20 to 70% by mass, particularly preferably 30 to 60%. It is the range of mass%.

The average molecular weight of the fluorine-containing vinyl polymer is not particularly limited, but the weight average molecular weight is 1,000.
-500,000 are preferable, More preferably, it is 5,000-200,000. If the weight average molecular weight is less than 1,000, the adhesion to the core silica may be insufficient, and if the weight average molecular weight exceeds 500,000, the amount introduced into the silica may be difficult to control. .

As the fluorine-containing polymer, fluorine-containing polymers other than the above-mentioned fluorine-containing vinyl polymers can also be used. In that case, regarding the fluorine-containing polymer other than the fluorine-containing vinyl polymer, preferred average molecular weight and the like are the same as those of the fluorine-containing vinyl polymer.
As mentioned above, although the preferable form in a fluorine-containing polymer was explained in full detail, the particle | grains which have the surface layer which satisfy | fill these suitable conditions are negatively charged when triboelectrically charged, and also the particle | grains with a high absolute value of this triboelectric charge amount Become.
The silica that is the core material of the particles of the present invention will be described.
As described above, the silica is characterized in that the specific surface area ratio (S / Ss ₀ ) to the theoretical surface area Ss _{0 represented} by the following formula (1) satisfies 2 or less.
Ss ₀ (m ² / g) = 6 / (ρ × d) (1)
ρ: True specific gravity of silica d: Average primary particle diameter of silica (μm)
When the specific surface area ratio (Ss / Ss ₀ ) of silica exceeds 2, the hygroscopicity of silica becomes high, the adhesion with the surface layer containing the fluorine-containing polymer becomes insufficient, and the hygroscopicity of the particles of the present invention Increases nature.
In view of the high adhesion of the surface layer containing the fluorine-containing polymer to silica, silica is further excellent in ineffectiveness and non-hygroscopic, and the amount of isolated silanol is preferably within a predetermined range.
Silica preferably has a nonporous surface. Specifically, the specific surface area ratio (Ss / Ss ₀ ) preferably satisfies 1.5 or less, more preferably 1.3 or less, and further preferably 1.2 or less. The specific surface area ratio (Ss / Ss ₀ ) preferably satisfies 0.8 or more, and more preferably satisfies 1.0 or more. The specific surface area (Ss) E. T.A. Values measured by the method can be used.
The content of isolated silanol groups in silica is preferably 0.01 to 5 mmol / g. The content of the isolated silanol group can be measured by, for example, the lithium aluminum hydride method or the FT-IR method.

Since the silica which is the core material according to the present invention has the above-described preferable characteristics, the hygroscopicity of the silica is low. Specifically, the moisture content measured by the Karl Fischer method after being left for 24 hours in an atmosphere of a temperature of 30 ° C. and a relative humidity of 90% is 1% by mass or less. More preferably, it is 0.5% or less, more preferably 0.2% or less, and particularly preferably 0.1% or less.
Silica, which is the core material, usually shows negative charge when frictionally charged, and the absolute value of the frictional charge amount is 10 μc / g or more. Preferably, it is 10-50 μc / g.
The silica which is the core material according to the present invention is also preferably amorphous in terms of X-ray diffraction. It is excellent in adhesiveness with the surface layer containing a fluorine-containing polymer if it is amorphous. Whether the silica is amorphous or crystalline can be confirmed by powder X-ray diffraction measurement.
The shape of the silica is preferably substantially spherical. The ratio of the longest diameter to the shortest diameter of the particles is preferably 0.90 or more, more preferably 0.92 or more, more preferably 0.95 or more, and particularly preferably 0.98 or more.
Silica is preferably in the form of primary particles whose surface is coated with a surface layer containing a fluorine-containing polymer. When silica is a secondary aggregate of primary particles or a fusion of primary particles, the particles of the present invention on which a surface layer containing a fluorine-containing polymer is formed may not exhibit a sufficient triboelectric charge amount. is there.
Whether the silica is a secondary agglomerate or fused product or is composed of primary particles can be confirmed by observing the silica with a scanning electron microscope or a transmission electron microscope.
The lower limit of the average primary particle diameter of silica is preferably 0.01 μm, more preferably 0.1 μm, and even more preferably 0.15 μm. The upper limit is preferably 3 μm, more preferably 2 μm, more preferably 1 μm, and particularly preferably 0.4 μm. Moreover, the average value of the primary particle diameter of particle | grains can be calculated | required by measuring the diameter of 50-100 particle | grains from said electron microscope image, and calculating the average (number average).

  Further, the coefficient of variation of the primary particle diameter of the particles is preferably 20% or less, more preferably 10% or less, and particularly preferably 5% or less. The variation coefficient of the primary particle diameter of the particles is calculated by the following formula. In addition, the standard deviation of a particle diameter means the arithmetic standard deviation of the particle size distribution of the number reference | standard obtained by measuring the diameter of 50-100 particles from an electron microscope image, for example.

Coefficient of variation (%) = (standard deviation of primary particle size / average value of primary particle size) × 100
The dispersion average particle diameter of silica is not particularly limited, but the ratio of the dispersion average particle diameter to the average primary particle diameter is preferably close to 1. Specifically, it is preferably 5 or less, more preferably 2 or less, and particularly preferably 1.5 or less. The lower limit of the dispersion average particle diameter is preferably 0.01 μm, more preferably 0.05 μm, and even more preferably 0.15 μm. The upper limit is preferably 5 μm, more preferably 2 μm, more preferably 1 μm, and particularly preferably 0.4 μm. The dispersion average particle diameter of the silica means an arithmetic average value of a volume-based particle size distribution obtained by measurement using a laser diffraction / scattering particle size distribution measuring device (LA-920 manufactured by Horiba, Ltd.).

  The coefficient of variation of the dispersed particle diameter of silica is not particularly limited, but is preferably 50% or less, more preferably 30% or less, and particularly preferably 20% or less. The variation coefficient of the dispersed particle size is usually 2% or more. The variation coefficient of the dispersed particle diameter of silica is calculated by the following formula. The standard deviation of the dispersed particle size means the arithmetic standard deviation of the volume-based particle size distribution obtained by measuring with a laser diffraction / scattering particle size distribution measuring device (LA-920 manufactured by Horiba, Ltd.).

Coefficient of variation (%) = (standard deviation of dispersed particle size / dispersed average particle size) × 100
As described above, silica with suppressed hygroscopicity and a uniform particle size distribution can be preferably produced by firing silica particles made of a hydrolysis condensate of alkoxysilane at 650 to 1180 ° C.

Further, the silica according to the present invention may have a surface introduced with an organic group such as a polymerizable group. The introduction method is not particularly limited, but a method of surface-treating silica as a core material with a silane compound (I) or a silazane compound represented by the following formula (4), or by hydrolytic condensation reaction of alkoxysilane, Examples include a method of introducing the silane compound (I) by cohydrolysis condensation with alkoxysilane in the reaction step of preparing silica particles as a silica raw material. In order to reliably obtain the effect of introducing an organic group such as a polymerizable group, a surface treatment method is preferred.
R _m SiX _(4-m) (4)
(In the formula, R may have a substituent and represents at least one group selected from the group consisting of an alkyl group, an aryl group, an aralkyl group, and an unsaturated aliphatic residue, and X is a hydroxyl group. , Represents at least one group selected from the group consisting of an alkoxy group and an acyloxy group, and m is an integer from 1 to 3.)
Among the silane compounds (I), those in which R is an unsaturated aliphatic residue are preferable, and those in which a radical polymerizable group is particularly preferable. As the radical polymerizable group, those represented by the following formulas (5), (6) and (7) are preferable.
^{CH2 = C (-R a) -COOR} b - ····· (5)
(In the formula, R ^a represents a hydrogen atom or a methyl group, and R ^b represents a C 1-20 divalent organic group which may have a substituent.)
CH2 = C (−R ^c ) − (6)
(In the formula, R ^c represents a hydrogen atom or a methyl group.)
^{CH2 = C (-R d) -R} e - ······ (7)
(In the formula, R ^d represents a hydrogen atom or a methyl group, and R ^e represents an optionally substituted divalent organic group having 1 to 20 carbon atoms.)
Examples of the radical polymerizable group represented by the formula (5) include an acryloxy group and a methacryloxy group. Examples of the radical polymerizable group represented by the formula (6) include a vinyl group and an isopropenyl group. Examples of the radical polymerizable group represented by the formula (7) include a vinylphenyl group (styryl group) and an isopropenylphenyl group.
Examples of the silane compound (I) having a radical polymerizable group of the above formulas (5) to (7) include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyl Triethoxysilane, styryltrimethoxysilane, 1-hexenyltrimethoxysilane, 1-hexenyltriethoxysilane, and the like are preferable because of excellent industrial availability.
Further, compounds in which R is an aryl group such as naphthyltrimethoxysilane and diphenyldimethoxysilane; compounds in which R is an aralkyl group such as benzyltrimethoxysilane; methyltrimethoxysilane, butyltrimethoxysilane, hexyltrimethoxysilane, decyl Compounds having an alkyl group such as trimethoxysilane, stearyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, triethylethoxysilane, and trimethylsilanol can be preferably used as the silane compound (I).
(Method for producing particles)
Although the manufacturing method of the particle | grains of this invention is not specifically limited, A preferable manufacturing method is demonstrated. A preferred method for producing the particles of the present invention is a step of producing silica having a specific surface area ratio (Ss / Ss ₀ ) to a theoretical surface area (Ss ₀ ) represented by the following formula (2) of 2 or less. (Silica production step) and a step of forming a surface layer containing a fluorine-containing polymer on the silica (surface layer formation step).
Ss ₀ (m2 / g) = 6 / (ρ × d) (2)
ρ: True specific gravity of silica d: Average particle diameter of silica (μm)
(Silica production process)
The silica production process is not particularly limited, but the process (1) of producing silica particles by hydrolyzing and condensing alkoxysilane, and producing silica as a core material by firing the silica particles at 650 to 1180 ° C. It is preferable that the process (2) to include is included.
A process (1) for producing silica particles (hereinafter also referred to as a silica particle production process) will be described.
This step is preferably a step of producing silica particles by hydrolyzing and condensing alkoxysilane in an organic solvent in the presence of a basic catalyst and water.

The alkoxysilane includes a composition formula R ′ _n SiX _4-n (wherein R is at least one selected from the group consisting of an optionally substituted alkyl group, aryl group, and unsaturated fatty acid residue). An organic group, X represents an alkoxy group, n represents an integer of 0 to 3, and R ′ and X may be the same or different from each other) Since it is easily available and inexpensive, it is preferably used. However, when a silicon compound in which the integer represented by n in the composition formula is 2 or 3 and / or its derivative is used as a raw material, the integer represented by n in the composition formula is 0 or 1 It is preferable to use together a silicon compound and / or a derivative thereof.

  Examples of the alkoxysilane include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, and trimethylethoxy. Silane, dimethoxydiethoxysilane, 3-chloropropylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, 3-glycidoxypropyl Trimethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3- (2-aminoethyl) Amino) propyl trimethoxysilane, 3-glycidoxypropyl methyl dimethoxysilane, 3-glycidoxypropyl methyl diethoxy silane and the like. These alkoxysilanes may be used alone or in combination of two or more. Among the alkoxysilanes exemplified above, tetraalkoxysilane in which n is 0 is preferable, and tetramethoxysilane and tetraethoxysilane are more preferable.

  The method for adding / mixing alkoxysilane, basic catalyst, water, and organic solvent is not particularly limited. For example, a method in which alkoxysilane is added to an organic solvent containing basic catalyst and water and stirred, Various methods such as a method of adding an alkoxysilane in several portions while stirring an organic solvent containing a basic catalyst and water, a method of adding an alkoxysilane continuously while stirring an organic solvent containing a basic catalyst and water, etc. This method can be adopted. Alternatively, a solution in which alkoxysilane is dissolved in an organic solvent can be prepared in advance, and the solution can be added to an organic solvent containing a basic catalyst and water by employing the various methods described above. Accordingly, the timing of adding and mixing the alkoxysilane, basic catalyst, water, and organic solvent should be appropriately devised.

Examples of the basic catalyst include ammonia; ammonia generators such as urea capable of generating ammonia by heating; aliphatic amines such as methylamine, ethylamine, propylamine, n-butylamine, dimethylamine, dibutylamine, trimethylamine, and tributylamine. Alicyclic amines such as cyclohexylamine; aromatic amines such as benzylamine (hereinafter, aliphatic amine, alicyclic amine and aromatic amine are collectively referred to as “amines”); tetramethylammonium hydroxide, etc. Examples include quaternary ammonium hydroxides; quaternary ammonium salts such as tetramethylammonium chloride; alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine.
Among these, ammonia, amines, and alkanolamines are preferable in that silica particles with a controlled particle diameter can be easily obtained. Moreover, ammonia and a C1-C4 aliphatic amine are preferable at the point which has a low boiling point and is easy to reduce the residual amount to the obtained silica particle or silica particle dispersion. Furthermore, ammonia is particularly preferable because it has a high effect of promoting the hydrolysis reaction between alkoxysilane and water, and the amount remaining in the resulting silica particles or silica particle dispersion can be easily reduced.

  The organic solvent only needs to be a compound that dissolves the alkoxysilane, dissolves the basic catalyst and water, or can uniformly disperse in a state where the basic catalyst and water are associated (in micellar form). . Examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, t-butyl alcohol, pentyl alcohol, ethylene glycol, propylene glycol, and 1,4-butanediol; acetone, methyl ethyl ketone Ketones such as ethyl acetate; (cyclo) paraffins such as isooctane and cyclohexane; (cyclic) ethers such as dioxane and diethyl ether; aromatic hydrocarbons such as benzene and toluene; . These organic solvents may be used alone or in combination of two or more. Of the organic solvents exemplified above, alcohols are particularly preferable. In addition, although a basic catalyst and an organic solvent incompatible with water can be used, in this case, a surfactant may be added to uniformly disperse the basic catalyst and water.

  The concentration of alkoxysilane contained in the organic solvent is preferably 0.05 mol / L or more, and more preferably 3.0 mol / L or less. The concentration of water is preferably 0.1 mol / L or more, and more preferably 2 mol / L or more. The concentration of water is preferably 50 mol / L or less, and more preferably 25 mol / L or less. The concentration of the basic catalyst is preferably more than 0.1 mol / L, and more preferably 0.8 mol / L or more. Further, the concentration of the basic catalyst is preferably 10 mol / L or less, and more preferably 9.4 mol / L or less.

The reaction temperature when hydrolyzing and condensing alkoxysilane is preferably 0 ° C or higher, more preferably 10 ° C or higher, and further preferably 20 ° C or higher. The reaction temperature is preferably 100 ° C. or lower, more preferably 70 ° C. or lower, and further preferably 50 ° C. or lower. If reaction temperature is 0 degreeC or more, a hydrolysis and a condensation reaction will advance rapidly, and if it is 100 degrees C or less, control of a hydrolysis and a condensation reaction will become easy. The reaction temperature means the temperature of the reaction solution.
The reaction time for hydrolyzing and condensing the alkoxysilane is preferably 30 minutes or more, more preferably 1 hour or more, and further preferably 2 hours or more. The reaction time is preferably 100 hours or less, more preferably 20 hours or less, and even more preferably 10 hours or less. If the said reaction time is 30 minutes or more, a hydrolysis and condensation reaction will fully advance, and if it is 100 hours or less, the energy required for heat processing can be restrained low and productivity will improve.

  Therefore, the most preferable reaction conditions for hydrolysis and condensation are that the concentration of alkoxysilane contained in the organic solvent is in the range of 0.05 mol / L to 3.0 mol / L, and the concentration of water is 2 mol / L to 25 mol. / L, the concentration of the basic catalyst A is in the range of 0.8 mol / L to 9.4 mol / L, the reaction temperature is in the range of 20 ° C. to 50 ° C., and the reaction time Is in the range of 2 to 10 hours. Hydrolysis and condensation of alkoxysilane in an organic solvent containing a basic catalyst and water makes it easier to obtain a dispersion containing silica particles having a spherical shape and a uniform particle size.

Since the concentration of alkoxysilane, the concentration of basic catalyst, the concentration of water, and the reaction temperature in the organic solvent may affect the particle size of silica particles, etc., depending on the desired average particle size and particle size distribution It is preferable to adjust appropriately.
Due to the hydrolytic condensation reaction in the above silica particle production process, silica particles having a substantially spherical average particle diameter of 0.01 to 5 μm, a particle diameter variation coefficient of 50% or less, and excellent dispersibility have a silica particle concentration of 1. It is obtained as a dispersion dispersed in an organic solvent at a ratio of about ˜15% by mass.

  The dispersion may contain coarse particles or agglomerated particles produced during the hydrolytic condensation reaction. In such a case, the dispersion is passed through a filter having a pore size that is 1 μm or more larger than the average particle size of the silica particles. It is also possible to remove coarse particles, aggregates, and the like. The filter may be a mesh having a suitably set gap or gap diameter.

In order to subject the silica particles to the step (2) for producing silica by firing (hereinafter also referred to as a firing step), preferably, the silica particles are isolated from the dispersion containing the silica particles, Preferably, the isolated silica particles are dried.
The isolation method is not particularly limited. For example, conventionally known separation methods such as filtration and centrifugation can be employed. Alternatively, separation and drying can be simultaneously performed by an evaporation method in which the dispersion is heated to evaporate the solvent. Or you may combine said method.
When the silica particles are separated from the dispersion containing the silica particles and the dried silica particle powder is prepared, it is preferable to be able to suppress aggregation and fixation of the silica particles. From such a viewpoint, it is preferable to adopt an air flow drying method or a spray drying method as a preferable method for preparing the silica particle powder. The dispersion of silica particles obtained by the hydrolysis-condensation reaction of alkoxysilane can be used as it is for the above drying method. However, by performing a concentration operation in which the dispersion is heated to evaporate and remove a part of the solvent. It is preferable to prepare a silica particle concentrated dispersion and use the concentrated dispersion as a raw material from the viewpoint of obtaining a powder in which aggregation, adhesion and the like are suppressed.
When the airflow drying method is employed, the silica particles are prevented from aggregating due to the airflow and / or the collision with the inner wall of the drying apparatus. As a method for heating the dispersion in this method, either a direct heating method or an indirect heating method may be selected. In the case of the direct heating method, the solvent of the dispersion liquid can be evaporated by bringing the hot air generated by a hot air generator or the like into contact with the concentrated dispersion liquid, and also generated by the hot air stream as the solvent evaporates. The disintegration of the aggregate of the silica particles can be promoted. In the case of the indirect heating method, the solvent of the dispersion can be evaporated by heating the concentrated dispersion through the heat conductive material, and the air flow introduced from the outside or the air circulating inside is used. The dispersion of the dispersion and the crushing of the aggregates of the silica particles can be promoted.
When a spray drying method is employed as the drying method, the dispersion of the dispersion and the crushing of the aggregates of the silica particles can be promoted by spraying the concentrated dispersion. In order to suppress the agglomeration of silica particles accompanying the evaporation of the solvent of the dispersion, the spray drying method instantaneously heats the solvent of the dispersion to a high temperature and maintains the pressure in the drying system at a low pressure. A vacuum instantaneous drying method in which the solvent is evaporated by evacuation is preferable. Further, in order to sufficiently disintegrate the silica particle aggregate, a tube composed of a straight portion where the solvent is evaporated and a bent portion is provided and evacuated from the outlet side (bent portion side) of the tube. However, a device that can supply the dispersion from the inlet side (straight line side) of the tube is used. If such an apparatus is used, even if silica particles agglomerate due to solvent evaporation, the agglomerates are crushed by colliding the agglomerates with the walls of the bent portions.
In addition, even if it uses the said drying system selected, depending on conditions, the aggregate may be produced | generated or remain | survived in silica particle powder. In this case, you may perform a crushing process separately.
As described above, silica particles having a substantially spherical average particle diameter of 0.01 to 5 μm, a particle diameter variation coefficient of 50% or less, and excellent dispersibility are obtained in a powder state by the silica particle production process.
Usually, the silica particles have an alkoxy group derived from the alkoxysilane used as a raw material for the hydrolysis condensation reaction or an alkoxy group derived from the alcohol used when an alcohol is used as the organic solvent. Bonded to a silicon atom.
The silica particles obtained in the silica particle production process usually have high hygroscopicity and are not suitable for silica as the core material of the particles of the present invention. As described above, the silica preferably has a specific surface area ratio and is suppressed in hygroscopicity, and the isolated silanol group content is preferably in the predetermined range.
A baking process is a process implemented in order to make a silica particle the silica which has the said characteristic.
As for the calcination temperature in this process, 650-1180 degreeC is preferable. More preferably, it is 800-1150 degreeC. If the firing temperature is less than 650 ° C., the specific surface area ratio may be greater than 2, and the hygroscopicity may not be sufficiently low. If the firing temperature exceeds 1180 ° C., the silica particles may be fused. Even if a surface layer containing a fluorine-containing polymer is formed, it is difficult to achieve a triboelectric charge amount of 50 μc / g or more in absolute value.
The atmosphere at the time of firing is not particularly limited, but any of an oxidizing atmosphere such as air, nitrogen-oxygen mixed gas, and an inert gas atmosphere such as nitrogen gas, argon gas, helium gas can be adopted.
An oxidizing atmosphere is preferred. This is because the alkoxy groups bonded to the silica particles are efficiently burned and removed, and the condensation reaction between the silanols generated by the elimination of the alkoxy groups is easily promoted.

  When firing, the silica particles are heated from around normal temperature in the heating path and heated at the firing temperature for a predetermined time. At this time, the rate of temperature rise is not particularly limited, but is preferably 0.5 to 10 ° C./min because it is difficult to generate an alkoxy group combustion residue. More preferably, it is 1-5 degreeC / min. The heating and holding time at the firing temperature is not particularly limited, but is preferably 0.5 to 24 hours, more preferably 1 to 12 hours, and particularly preferably 2 to 8 hours.

  It is preferable to cool after holding at the firing temperature for a predetermined time. The cooling rate during cooling is preferably 0.5 to 10 ° C./min, more preferably 1 to 5 ° C./min.

By firing under the above-mentioned preferred conditions, the above-described preferred form of silica can be obtained.
Before forming the surface layer containing the fluorine-containing polymer, the silica as the core material is surface-treated with the silane compound (I) or silazane compound represented by the following formula (4) as necessary. Is preferred.
The preferable form of silane compound (I) is as above-mentioned, and the silane compound which has a polymeric group of above-described Formula (5)-(7) is used especially suitably.
R _m SiX _(4-m) (4)
(In the formula, R may have a substituent and represents at least one group selected from the group consisting of an alkyl group, an aryl group, an aralkyl group, and an unsaturated aliphatic residue, and X is a hydroxyl group. , Represents at least one group selected from the group consisting of an alkoxy group and an acyloxy group, and m is an integer from 1 to 3.)
The surface treatment method is not particularly limited. For example, the silane compound (I) or the silazane compound (hereinafter also referred to as a surface treatment agent) may be sprayed onto the silica while stirring the silica in a known mixer such as a Henschel mixer. During spraying, silica is provided in an atmosphere such as nitrogen. It is preferable to heat the silica after spraying the surface treatment agent. The heating temperature is preferably 100 ° C. or higher and 250 ° C. or lower, more preferably 120 ° C. or higher and 230 ° C. or lower, and more preferably 150 ° C. or higher and 200 ° C. or lower. The heating time is preferably 1 hour or more and 10 hours or less, more preferably 2 hours or more and 8 hours or less, and more preferably 3 hours or more and 6 hours or less.

It is preferable that the usage-amount of a surface treating agent is 0.1-30 mass% with respect to 100 mass% of silica. More preferably, it is 1-20 mass%, More preferably, it is 5-15 mass%.
(Surface layer forming step)
A step of forming a surface layer containing a fluorine-containing polymer on the surface of silica (surface layer forming step) will be described. The same applies to the surface-treated silica.
The method for forming the surface layer is not particularly limited.

For example, the fluorine-containing polymer is mixed in a state where silica as a core material is dispersed in an organic solvent. After the fluorine-containing polymer is uniformly dissolved, the solvent is removed and the method is dried. Depending on the solvent removal / drying method, particles in which a surface layer containing a fluorine-containing polymer is formed on the silica can be obtained in an agglomerated state or in an agglomerated state.
For example, specific examples of the solvent removal / drying method include the method using the airflow drying method, the method using the heating spray method, and the method of simply distilling off the solvent while heating. When it is obtained in the state of aggregates, if some aggregates are contained, the aggregates are crushed and classified. A conventionally known method may be used as the crushing classification method.

The organic solvent is not particularly limited, but aromatic hydrocarbons, aliphatic (chain, cyclic) hydrocarbons, ketones, esters, alcohols, alkylene glycol derivatives (ethers, esters), etc. are preferably used. Can do. In order to form a surface layer uniformly on the surface of the silica, it is important that the silica is dispersed without agglomeration and that the fluorine-containing polymer is in contact with the silica in a uniformly dissolved state. Therefore, it is preferable to select an organic solvent as appropriate in consideration of these factors. Examples of the solvent in which silica is easily dispersed include ketones, alcohols, and hydrocarbons, and it is preferable to select a solvent having high solubility in the fluorine-containing polymer from these.
As another method for forming the surface layer, the same method as described in the surface treatment with the silane compound (I) or the silazane compound, that is, while stirring the silica in a known mixer such as a Henschel mixer, A method of spraying a fluorine-containing polymer can also be employed. In addition, when processing with the fluorine-containing polymer mentioned above, you may form the surface layer which consists of a polymer component other than a fluorine-containing polymer, etc. coexisted, and consists of a mixture of a fluorine-containing polymer and polymers other than this polymer.
The above is a method in which a fluorine-containing polymer is prepared in advance and a surface layer is formed on the silica surface as the core material. The surface layer containing the fluorine-containing polymer while directly forming the fluorine-containing polymer on the silica surface A method of forming can also be employed. For example, silica prepared by surface treatment with a silane compound having a polymerizable group represented by the above formulas (5) to (7) is prepared, and a fluorine-containing vinyl monomer is essential on the silica surface. The method of graft-polymerizing a vinyl monomer is mentioned. Specifically, a vinyl-based resin in which a fluorine-containing vinyl monomer is essential in the presence of a polymerization initiator in a dispersion obtained by dispersing silica, which is surface-treated with a silane compound having a polymerizable group, in an organic solvent. A method in which the monomer is heated and radically polymerized while being supplied is preferably employed. By following the production method described above, the particles of the present invention are obtained.
(Use of particles)
Since the particles of the present invention are suppressed in hygroscopicity and excellent in triboelectric charging characteristics, such as external additives for toner, industrial fields where excellent charging characteristics due to friction are required, and industrial fields for the purpose of charge control. It can be preferably used.

When the particles of the present invention are used as an external additive for toner, the toner usually has a colorant and a binder resin. As the colorant, dyes and pigments such as carbon black, cyan color, magenta color, yellow color and extender pigments can be used. The binder resin includes monoolefins such as styrene, propylene, butylene and isobutylene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; methyl acrylate, ethyl acrylate, butyl acrylate, Esters of α-methylene aliphatic monocarboxylic acids such as dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, phenyl acrylate; vinyl methyl ether, vinyl ethyl Vinyl ethers such as ether and vinyl butyl ether; homopolymers or copolymers of vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropyl ketone;
Further, the toner may contain, as additives, a magnetic substance such as ferrite, a charge control agent, a conductivity regulator, a reinforcing filler such as a fibrous substance, an antioxidant, and a release agent.
When the particles of the present invention are used as an external additive for the toner, the content of the particles is appropriately set depending on the type of toner. When the toner is non-magnetic, the amount of particles used is preferably 0.1% by mass or more, more preferably 0.1 to 10% by mass, and more preferably 100% by mass of the toner. 0.5 to 5% by mass. If the amount of particles used is less than 0.1 parts by mass, the chargeability of the toner may not be controlled. Further, when the toner is a magnetic toner, the amount of particles used may be set similarly for 100% by mass of the toner excluding the magnetic material. In order to mix the toner and the particles of the present invention, a known mixing means and a known mixing apparatus can be applied. Examples of the apparatus include a Henschel mixer, a Nauter mixer, a ball mill, a V-type mixer, a tumbler mixer, and a paint shaker.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples, and the present invention is implemented with appropriate modifications within a range that can be adapted to the spirit described above. All of which are within the scope of the present invention.

In each Example and Comparative Example, primary particle diameter average value, dispersion average particle diameter, coefficient of variation of dispersion particle diameter, specific surface area, water content / hygroscopicity, fluorine content (unit ratio in particle surface layer) for silica and particles The fluorine content per surface area), the polymer content, the carbon content, the degree of hydrophobicity, the triboelectric charge amount, and the alcohol bond amount in silica were evaluated as follows.
<Method for measuring silica, dispersion average particle size of particles, standard deviation of dispersed particle size>
Particles were mixed in a 10% sodium dodecylbenzenesulfonate solution so as to have a concentration of 2% by mass, and the particles were dispersed for 10 minutes or more by an ultrasonic disperser to obtain a measurement sample. This sample was measured using a laser diffraction / scattering particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.). The arithmetic average value of the obtained volume-based particle size distribution was used as the average particle size, and the arithmetic standard deviation value of the volume-based particle size distribution was used as the standard deviation of the particle size. It measured similarly about the silica.
<Calculation method of coefficient of variation of silica and particle diameter>
The variation coefficient of the particle diameter was calculated as follows from the average particle diameter and standard deviation obtained by measurement with a laser diffraction / scattering particle size distribution measuring apparatus (LA-920 manufactured by Horiba, Ltd.).
Coefficient of variation (%) = (standard deviation of particle diameter / average particle diameter) × 100
<Silica, specific surface area of particles>
The specific surface area is B.I. E. T.A. Measured by the method.

The measuring device used was Macsorb 1201 manufactured by Mountec.
Further, the ratio of specific surface area value obtained by measurement to the theoretical surface area: specific surface area ratio (S / S ₀ ) was calculated. In the table, the specific surface area ratio expressed by rank is based on the determination based on the following criteria.
0.6 ≦ (S / S ₀ ) ≦ 1.5: Rank A
1.5 <(S / S ₀ ) ≦ 2: Rank B
0.6> (S / S ₀ ) and 2 <(S / S ₀ ): Rank C
The theoretical surface area S ₀ was determined according to the following formula.
S ₀ (m ² / g) = 6 / (ρ · d)
ρ: True specific gravity of silica (or particles) d: Average particle diameter (μm) of silica (or particles)
<Water content of silica and particles>
Place 5 g of silica on a watch glass with a diameter of 10 cm and spread it thinly. Thereafter, it is left for 24 hours in an atmosphere of a temperature of 30 ° C. and a relative humidity of 90%. The water content of the silica after standing was measured by the Karl Fischer method, and this was used as the water content.

The water content of the particles was measured in the same manner.
<Average value of primary particle diameter of particles and silica>
Using SEM (Hitachi, Ltd., scanning electron microscope “S-3500N”), 5 samples can be randomly observed at about 10,000 magnifications for about 50 to 100 samples (particles, silica). Images were taken, and the diameters of the primary particles of the sample that could be confirmed from all the photographed images were randomly measured. From this measured value, an average value was calculated and used as an average primary particle diameter value. Further, the primary particle diameter average value and the standard deviation of the particle diameter were applied to the following equation to obtain the coefficient of variation of the primary particle diameter.
Coefficient of variation (%) = (standard deviation of particle diameter / average value of primary particle diameter) × 100
<Fluorine content per unit surface area in particle surface layer>
The fluorine content (g / m ² ) per unit surface area is calculated from the measured value obtained by measuring the fluorine content (% by mass) in the particles and the measured specific surface area (m ² / g). did. As a precaution, the silica content of the core material is analyzed by the same method, and when fluorine is detected, the corrected value obtained by subtracting the analysis value from the fluorine content in the particles is expressed in units. Used to calculate the fluorine content per surface area. Therefore, the fluorine content per unit surface area referred to here is the content per unit particle specific surface area of fluorine contained in the surface layer.
The fluorine content in the particles and silica was measured by anion chromatography. The sample preparation method in the anion chromatography method is as follows.

Sample preparation method: In the same manner as the oxygen combustion flask method of JIS6233-1 (S determination), put 10 ml of water into a 300 ml flask, weigh 3 mg of the sample, wrap it in filter paper, put it in a platinum coil, and put it in the flask. The sample was completely burned. The flask was immersed in cold water for 30 minutes and shaken 200 times. Thereafter, the wall surface of the flask was washed with 20 ml of water to dissolve F ions with water. The sample was measured with the following measuring machine. Anion chromatography analysis used DX-320 manufactured by Dionex.
<Polymer content in particles>
Using TG-DTA, the weight reduction rate was measured when the temperature was increased from room temperature to 500 ° C. at a temperature increase rate of 10 ° C./min in an air atmosphere, and this was defined as the fluorine-containing polymer content (% by mass) in the particles. .
In addition, when the alcohol was couple | bonded with the silica used for the polymer coating raw material, what subtracted the alcohol coupling | bonding amount mentioned later from the value of the said weight reduction rate was made into fluorine-containing polymer content.
<Fluorine-containing polymer amount per unit surface area of particle>
From the fluorine-containing polymer content and the specific surface area value (m ² / g) of the particles based on the measurement method described above, the fluorine-containing polymer amount per unit specific surface area of the particles was calculated.
<Carbon content of silica and particles>
Elemental analysis Measured with a CHNO coder (MT-5 manufactured by J-Science).
<Hydrophobicity of silica and particles>
50 cc of ion-exchanged water was put into a 200 cc glass beaker with a stirrer placed at the bottom, and 0.2 g of silica was placed on the water surface, and then the sales spreader was gently rotated. Thereafter, the tip of the burette was inserted into the water in the beaker, and methanol was gradually introduced into the water from this burette. This introduction was performed until it was confirmed visually that the silica on the water surface had completely sunk. Then, the degree of hydrophobicity was determined based on the following formula.

Hydrophobicity (%) = {methanol introduction amount (cc)} × 100 / {water amount (cc) + methanol introduction amount (cc)}
Here, the amount of methanol introduced is the amount of methanol introduced when it was confirmed that the silica was completely sunk. Regarding the particles, the same evaluation method was used except that the particles were used instead of silica.
<Abrasive charge of silica and particles>
A mixture of 0.5 part by mass of silica and 100 parts by mass of iron powder having an average particle diameter of 100 μm as carrier particles was ground and mixed in an agate mortar for 5 minutes. Using the ground mixture as a sample, the blow-off charge amount was measured using a blow-off charge amount measuring device (“TB-200” manufactured by Kyocera Chemical Co., Ltd.). The measurement conditions here were a mesh of 400 mesh, a blow pressure of 0.02 MPa, and a blow time of 20 seconds. Regarding the particles, the same evaluation method was used except that the particles were used instead of silica.
<Alcohol bond amount in silica>
About 1 g of silica was precisely weighed, placed in 50 mL of 0.05N aqueous sodium hydroxide solution, and stirred at room temperature for 10 hours to obtain a suspension. The suspension was centrifuged with a centrifugal force at a centrifugal force of 100,000 G or more for 60 minutes, and the supernatant was collected. The supernatant was analyzed by gas chromatography to determine the amount of alcohol bound. As a detector of the gas chromatograph, a flame ionization detector (FID) was used. Gas chromatographic analysis was in accordance with JIS K 0114.
[Example 1]
(Polymer synthesis)
A 1 L flask equipped with a stirrer, two dripping tanks (one for the monomer and one for the catalyst), a thermometer, and a condenser was prepared. Fluorine-containing acrylate monomer (Kyoeisha Chemical Light Ester FM-108): 90 g, cyclohexyl methacrylate (Mitsubishi Rayon acrylic ester CH) 90 g, 3-methacryloxypropyltrimethoxysilane (Shin-Etsu Chemical KBM-503) A mixture in which 20 g was uniformly mixed was charged. The catalyst dropping tank was charged with a mixture in which 10 g of an azo polymerization initiator (V-59 manufactured by WAKO) and 40 g of toluene were uniformly mixed.
Into the flask (bottom) was charged 150 g of toluene, and the temperature was raised to 110 ° C., and then dropped from a monomer dropping tank and a catalyst dropping tank over 4 hours from separate dropping ports while maintaining the temperature at 110 ° C. After completion of the dropping, the mixture was aged at 110 ° C. for 2 hours, and then an initiator solution in which 1 g of V-59 and 10 g of toluene were uniformly mixed was added as a booster. Thereafter, the solution was further heated for 2 hours and then cooled to obtain a solution containing the fluorine-containing polymer (1).
(Preparation of silica particles)
A 200 L reactor equipped with a stirrer, a dropping device, a thermometer, and a condenser was charged with 67.54 kg of methyl alcohol and 26.33 kg of 28% by mass ammonia water (water and catalyst), and the liquid temperature was 33 ± 0 while stirring. Adjusted to 5 ° C. On the other hand, a solution prepared by dissolving 13.45 kg of tetramethoxysilane and 5.59 kg of methyl alcohol was charged into a dropping device. Dispersion containing silica particles by hydrolyzing and condensing tetramethoxysilane by stirring while maintaining the liquid temperature in the reactor at 33 ± 0.5 ° C. while maintaining the temperature from the dropping device. Got. Thereafter, the dispersion was heated under reduced pressure to perform concentration so that the silica particle concentration was 30%.
Using the obtained concentrated dispersion as a raw material, dried silica particles were obtained by air-flow drying with an instantaneous vacuum evaporator. As an instantaneous vacuum evaporator, a CRAX system 8B type (manufactured by Hosokawa Micron) was used. As drying conditions, a heating tube temperature of 175 ° C. and a degree of vacuum of 200 torr (27 kPa) were employed. The instantaneous vacuum evaporator includes a stainless steel pipe having an inner diameter of 8 mm and a length of 9 m covered with a jacket to which heated steam is supplied, a supply section for supplying a dispersion containing silica particles to one end of the steel pipe, and the other end of the steel pipe A powder collecting chamber in a decompressed state provided with a bag filter for separating the powder and vapor connected to each other. In the steel pipe, the silica particle-containing dispersion liquid supplied from the supply section is indirectly heated to evaporate the solvent, and the powder collection side is depressurized, and the silica particle-containing dispersion liquid dispersion and silica Crushing of the particle aggregate is promoted. The silica particle powder is transferred through the steel pipe by an air flow created by reducing the pressure on the powder collecting side, and is collected by a bag filter. After passing through the bag filter, the vapor is condensed and then discharged out of the apparatus.
(Preparation of silica by firing silica particles)
The obtained silica particle powder is put in a crucible, heated in an air atmosphere at a heating rate of 4 ° C./min from an ordinary temperature in an air atmosphere, reached 1050 ° C., and further heated at 1050 ° C. for 1 hour. After holding, it was cooled. After cooling, the obtained silica was taken out and pulverized using a pulverizer to obtain about 0.13 kg of silica. The firing temperature is a value obtained by measuring the atmospheric temperature in the electric furnace.
The obtained silica has an average particle size of 0.26 μm, a particle variation coefficient of 14%, a specific surface area of 12 m 2 / g, a water content of 0.09%, a carbon content of 0%, and an isolated silanol group content of 0.2%. 3 mmol / g, the degree of hydrophobicity was 0%, and the triboelectric charge amount was −35 μc / g. Further, no binding of alcohol was observed.
(Polymer treatment)
0.3 kg of the obtained silica and 0.5 kg of methyl ethyl ketone were charged into a 1 L beaker and irradiated with an ultrasonic disperser for 1 hr to obtain a monodispersed silica MEK dispersion. 30 g of the fluorine-containing polymer (1) -containing solution as the polymer was added to the silica MEK dispersion, and the mixture was stirred for 1 hour. Next, the mixture was transferred to a 1 L eggplant-shaped flask, set in an evaporator, and started to distill at an atmospheric pressure of 150 ° C. in an oil bath. When the bottom slurry became cake-like, the operating pressure was set to 200 torr. It was dried under reduced pressure for 2 hours. Then, it cooled and the polymer processing silica was taken out.
By subjecting the polymer-treated silica to pulverization and classification with a jet pulverizer classifier (manufactured by Hosokawa Micron / Counterjet 100 type) having a pulverization pressure of 6 kg / cm 2, a surface layer containing silica and a fluorine-containing polymer (1) on the surface thereof To obtain particles (1).
[Example 2]
In Example 1, the surface layer containing the fluorine-containing polymer (1) on the surface of silica and the surface thereof was obtained by carrying out in the same manner as in Example 1 except that the temperature when firing the silica particle powder was 800 ° C. The formed particles (2) were obtained.
[Example 3]
Silica particles were synthesized in the same manner as in Example 1, and silica was prepared under the same firing conditions. 0.3 kg of the obtained silica was charged into a mixer (manufactured by Kawata, Supermixer Piccolo) and stirred. On the other hand, a homogeneous solution consisting of 15 g of vinyltrimethoxysilane (KBM-1003, manufactured by Shin-Etsu Chemical Co., Ltd.), which is a silane compound having a polymerizable group, in a 100 cc beaker and sprayed with 15 g of methanol was sprayed on the silica in 10 minutes. Then, the mixture of a silica and a silane compound was obtained by stirring for 1 hour. The resulting mixture was transferred to a SUS bat, heated from room temperature to 120 ° C. in a shelf dryer in 1 hour, dried at 120 ° C. for 3 hours, and then cooled to obtain a surface-treated silica powder. Got. The surface-treated silica was further pulverized with a jet pulverizer.
0.3 kg of the obtained surface-treated silica and 0.5 kg of methyl ethyl ketone were charged into a 1 L beaker and irradiated with an ultrasonic disperser for 1 hr to obtain a monodispersed silica MEK dispersion. 30 g of the fluorine-containing polymer (1) was added to the silica MEK dispersion and mixed uniformly, then transferred to a 1 L eggplant-shaped flask, set in an evaporator, and started distillation under an oil bath at 150 ° C. and normal pressure. When the bottom slurry became a cake, the operating pressure was set at 200 torr and dried under reduced pressure for 2 hours. Thereafter, the polymer-treated silica was taken out by cooling.
The obtained polymer-treated silica is subjected to pulverization and classification with a jet pulverizer classifier (manufactured by Hosokawa Micron / Counterjet 100 type) having a pulverization pressure of 6 kg / cm2, thereby containing the fluorine-containing polymer (1) on the surface thereof. Particles (3) having a surface layer formed were obtained.
[Example 4]
In Example 3, it was performed in the same manner as in Example 3 except that the firing temperature of the silica particles was 800 ° C.,
Particles (4) obtained by forming a surface layer containing silica and a fluorine-containing polymer (1) on the surface thereof were obtained.
[Example 5]
In the same manner as in Example 1, particles (5a) in which a surface layer containing silica and a fluorine-containing polymer (1) on the surface thereof were formed were obtained. 10 g of the particles (5a) were dissolved in 50 g of MEK, irradiated with an ultrasonic disperser for 1 hour, further dispersed at room temperature for 8 hours, then transferred to a centrifugal sedimentation tube, centrifuged at 10 G for 30 minutes, and solid-liquid separated. The supernatant was discarded, the solid content was taken out, 50 g of MEK was further added, and dispersion and solid-liquid separation were repeated twice by the same method as described above to obtain a precipitated cake. The obtained precipitated cake was heated at 120 ° C. and 50 torr for 1 hour to prepare polymer-treated particles. By crushing in the same manner as in Example 1, the fluorine-containing polymer (1) was added to the silica and the surface thereof. Particles (5) obtained by forming a surface layer containing them were obtained.
[Example 6]
In Example 5, a washing operation was performed in the same manner as in Example 5 except that the particles (3) obtained in Example 3 were used in place of the particles (5a), and silica and fluorine-containing surfaces were contained. Particles (6) obtained by forming a surface layer containing polymer (1) were obtained.
[Comparative Example 1]
In Example 1, particles (c1) in which a surface layer containing silica and a fluorine-containing polymer (1) was formed on the surface thereof were obtained in the same manner as Example 1 except that the silica particles were not baked. . In addition, the alcohol bond amount in silica was 9.0 mass%.
[Comparative Example 2]
In Example 3, particles (c2) are formed by forming a surface layer containing silica and a fluorine-containing polymer (1) on the surface in the same manner as in Example 3 except that the firing temperature of the silica particles is set to 1200 ° C. )

Table 1 shows various evaluation results regarding the particles and silica obtained in each of the examples and comparative examples.
From Table 1, the following can be confirmed.
(1) Even if the particles have a surface layer containing a fluorine-containing polymer, the particles (c1) shown in Comparative Example 1 having silica particles that do not satisfy the specific surface area ratio (S / S ₀ ) ≦ 2 as the core The amount of water is as high as 4.8%.
Therefore, it is considered that moisture is easily absorbed during storage, and charging is likely to attenuate after charging.
(2) Even if the particles have a surface layer containing a fluorine-containing polymer, the particle (c2) shown in Comparative Example 2 does not satisfy the firing temperature of 1200 ° C. and 1180 ° C. or less during the production of silica as a core. The triboelectric charge amount is −31 μc / g and an absolute value smaller than −50 μc / g, and is an agglomerated and fixed particle, which is difficult to use as an external additive for toner.
(3) The particles obtained in Examples 1 to 6 all satisfy the specific surface area ratio (S / S ₀ ) ≦ 2, the water content is extremely low at 0.1% or less, and the triboelectric charge amount is also an absolute value. Is 50 μc / g or more. In particular, in the particles obtained in Examples 5 and 6, although the ratio of the surface layer containing the fluorine-containing polymer was as small as about 1/3 of the other examples, the triboelectric charge amount was 100 μc / in absolute value. The amount of charge was not less than g and about twice the charge amount of the other examples.

Claims (12)

A particle comprising a surface layer containing silica and a fluorine-containing polymer formed on the surface thereof, wherein the specific surface area Ss of the silica is a specific surface area ratio (Ss /) to a theoretical surface area Ss _{0 represented} by the following formula (1): Ss ₀ ) is 2 or less, and the absolute value of the triboelectric charge amount of the particle is 50 μc / g or more.
Ss ₀ (m ² / g) = 6 / (ρ × d) (1)
ρ: True specific gravity of silica d: Average primary particle diameter of silica (μm)   The particle | grains of Claim 1 whose ratio of the said surface layer is 0.1-100 mg / m <2> per unit specific surface area of particle | grains.   The particle | grains of Claim 1 or 2 whose fluorine content in the said surface layer is 1-50 mass% with respect to 100 mass% of surface layers. The particle according to any one of claims 1 to 3, wherein the fluorine-containing polymer further has an alkyl group having 6 to 20 carbon atoms. The particle according to any one of claims 1 to 4, wherein the fluorine-containing polymer is a fluorine-containing vinyl polymer. The particle | grains of any one of Claims 1-5 whose water content is 0.3% or less when it is left for 24 hours in the atmosphere of 30 degreeC and 90% of relative humidity of the said particle | grain. The particle | grains of any one of Claims 1-6 whose isolated silanol group content of the said silica is 0.01-5 mmol / g.   The particle | grains of any one of Claims 1-7 whose said silica consists of single particle | grains. The particles according to any one of claims 1 to 8, wherein the silica is obtained by firing silica particles comprising a hydrolysis condensate of alkoxysilane at 650 to 1180 ° C.   The particle according to any one of claims 1 to 9, wherein the silica is surface-treated with a polymerizable silane compound. A step of producing silica having a specific surface area ratio (Ss / Ss ₀ ) of a specific surface area Ss to a theoretical surface area Ss _{0 represented} by the following formula (2), and forming a surface layer containing a fluorine-containing polymer on the silica The method for producing particles according to any one of claims 1 to 10, wherein the method comprises the step of:
Ss ₀ (m ² / g) = 6 / (ρ × d) (2)
ρ: True specific gravity of silica d: Average primary particle diameter of silica (μm) The step of producing the silica includes the step (1) of producing silica particles by hydrolyzing and condensing alkoxysilane, and the step of producing the silica by firing the silica particles in a temperature range of 650 to 1180 ° C. The method for producing particles according to claim 11, comprising (2).