JPH11322329A - Hydrophobic metal oxide particle and its production, and toner composition for electrophotography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide inexpensive metal oxide particles having sufficient hydrophobicity and controlled antistaticity, to provide a method for producing the same, and to provide an electrophotographic toner containing the hydrophobic metal oxide particles and having stable antistaticity and excellent flowability. SOLUTION: The hydrophobic metal oxide particles are obtained by treating the surfaces of metal oxide particles with an epoxy compound and an alkylsilazane. The rings of the epoxy groups on the surfaces of the produced hydrophobic metal oxide particles are thus opened with the decomposition product of the alkylsilazane to introduce amino groups and alkylsilyl groups. The toner composition for electrophotography contains the hydrophobic metal oxide particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a liquid-based resin and a rubber, which are used for thickening agents, reinforcing fillers, and to improve adhesion. Hydrophobic metal fine powder added for the purpose of improving the fluidity of the powder, preventing caking, adjusting charge, and the like, and a method for producing the same. The present invention relates to an electrophotographic toner composition having significantly improved stability, image characteristics, and cleaning properties (including not only electrophotography but also toners for developing various electrostatic images in electrostatic recording, electrostatic printing, and the like). .

[0002]

2. Description of the Related Art A metal oxide powder such as silica used as a thickener or a reinforcing filler for an organic liquid is usually treated with an alkylsilane or an organopolysiloxane to make the surface hydrophobic. . For example, JP-A-51-149
Japanese Patent Publication No. 00 discloses that the oxide fine powder is treated with an alkyl halide silane, and Japanese Patent Publication No. 57-2641 discloses that the oxide fine powder is treated with an organopolysiloxane.

In the powder system, a so-called surface-treated metal oxide powder obtained by treating the surface of a fine metal oxide powder such as silica, titania or alumina with an organic substance includes a copying machine, a laser printer, a plain paper facsimile and the like. In electrophotography, it is widely used as a toner external additive for the purpose of improving fluidity and controlling charging. In such applications, the flowability when the surface-treated metal oxide powder is mixed with the toner and the triboelectric charging property to iron or iron oxide as a carrier are important factors.

In this case, a negatively chargeable external additive is generally used for a negatively chargeable toner, and a positively chargeable external additive is used for a positively chargeable toner. A metal oxide as a positively chargeable toner fluidity improver generally has an amino group on its surface, and thus has a high affinity for water, and thus is liable to cause charging fluctuations due to environmental fluctuations, aggregation, etc. Is also likely to occur.

Various proposals have been made for such metal oxide powders into which amino groups have been introduced. For example, in Japanese Patent Application Laid-Open No. 62-52561, fumed silica is treated with an epoxy group-containing silane coupling agent. And then treating with amines. Further, Japanese Patent Application Laid-Open No. 58-1
No. 85405 discloses treating with an amino group-containing silane coupling agent and a hydrophobizing agent. JP-A-63-155155 discloses that a metal oxide powder is heated with an epoxy-containing modified silicone oil to be treated with an amino group-containing organic compound.

[0006]

In recent years, higher image quality of electrophotography has been required. As the particle size of toner has been reduced from 9 μm to 6 μm, the fluidity of the toner has deteriorated, and the fluidity has been improved. For the purpose, the addition amount of the toner external additive has been increased more than before, so that the toner external additive has greatly affected the chargeability of the toner. In particular, charging fluctuation due to the environment has become a problem, and a measure of hydrophobicity has also been emphasized.

[0007] On the other hand, a conventional metal oxide fine powder treated with an epoxy group-containing silane coupling agent or an amino group-containing organic compound has insufficient hydrophobicity, and is not suitable for long-term use or moisture absorption. This causes problems in terms of charging fluctuation and fluidity.

In the treatment with an amino group-containing silane coupling agent and a hydrophobizing agent, the amount of the amino group-containing silane coupling agent to be treated becomes zero or positively charged. However, it is not sufficiently hydrophobized, and disadvantages arise in terms of charge fluctuation and fluidity due to long-term use and moisture absorption. Also, there is a disadvantage that the amino group-containing silane coupling agent is expensive.

Further, even when a metal oxide fine powder is treated with an epoxy group-containing modified silicone or an amino group-containing organic compound, the hydrophobicity is not sufficient, and the charge fluctuation and the fluidity due to long-term use or moisture absorption are reduced. It is an obstacle.

An object of the present invention is to solve the above-mentioned conventional problems and to provide an inexpensive metal oxide fine powder having sufficient hydrophobicity and controlled charging properties, and a method for producing the same.

Another object of the present invention is to provide an electrophotographic toner which contains such a hydrophobic metal oxide fine powder, has stable charging properties, and is excellent in fluidity.

[0012]

Means for Solving the Problems The hydrophobic metal oxide fine powder of the present invention is obtained by subjecting the metal oxide fine powder to a surface treatment with an epoxy compound and an alkylsilazane, so that the epoxy groups on the surface of the metal oxide fine powder can be treated. It is characterized by introducing an amino group and an alkylsilyl group.

That is, the present inventors can control the charge amount by opening the ring of the epoxy group on the surface of the metal oxide fine powder with the decomposition product of alkylsilazane and introducing an amino group. Have found that by reacting a hydroxyl group generated by ring opening or a hydroxyl group of a metal oxide with an alkylsilyl group, the hydrophobicity can be increased and the charge control can be further performed, thereby completing the present invention.

In the present invention, the metal oxide fine powder is preferably silica, titania or alumina.

The epoxy compound includes a silane coupling agent having one or more epoxy groups in a molecule and / or an organopolysiloxane.

As the alkylsilazane, those represented by the following general formula (I) or (II) are preferable.

R ₃ Si (NHSiR ₂ ) _n NHSiR ₃ (I)

[0018]

Embedded image

(In the general formulas (I) and (II), R represents 1 carbon atom.)
Represents an alkyl group of 3 to 3, some of the substituents may be a hydrogen atom or another substituent such as a vinyl group;
m shows the integer of 3-6. The hydrophobic metal oxide fine powder of the present invention preferably has a hydrophobicity of at least 60% as measured by a transmittance method,
The triboelectric charge amount to iron powder is -400 to +400 µC / g
It is.

The hydrophobic metal oxide fine powder of the present invention is obtained by subjecting a metal oxide fine powder to a surface treatment with an epoxy compound and an alkylsilazane, so that an epoxy group on the surface of the metal oxide fine powder has an amino group and an alkylsilyl group. It is easily produced by the method for producing a hydrophobic metal oxide fine powder of the present invention into which a group is introduced.

The electrophotographic toner composition of the present invention is characterized by containing such a hydrophobic metal oxide fine powder of the present invention, and has good hydrophobicity and controlled chargeability. By containing the hydrophobic metal oxide fine powder, it has a stable chargeability and is extremely excellent in fluidity.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

As the metal oxide fine powder to be used as a raw material in the present invention, silica, titania, alumina, zirconia alone or a composite oxide thereof are preferably used, and two or more of these may be used in combination. In addition, these metal oxide fine powders are prepared in advance using trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylalkoxysilane, dimethyldialkoxysilane, methyltrialkoxysilane, hexamethyldisilazane, various silicone oils and various silane coupling agents. Hydrophobizing treatment may be performed.

The surface treatment in the present invention can be carried out by a conventionally known method. For example, a metal oxide fine powder produced by a gas phase high-temperature thermal decomposition method of a metal halide compound is put into a mixer under a nitrogen atmosphere. After stirring and dropping or spraying a predetermined amount of the epoxy compound and the alkylsilazane together with a solvent, if necessary, and sufficiently dispersing the mixture, 50 ° C or higher, preferably 100 ° C or higher, particularly preferably 100 to 100 ° C.
By stirring and heating at 200 ° C. for 0.1 to 5 hours, preferably 1 to 2 hours, and then cooling, a uniform surface-modified metal oxide fine powder can be obtained. In the surface treatment, the treatment of the epoxy compound and the alkylsilazane may be either simultaneous or two-step treatment.

In the present invention, as the epoxy compound as a surface treatment agent, a silane coupling agent having one or more epoxy groups such as a glycidyl group and / or an alicyclic epoxy group in a molecule, an organopolysiloxane and the like are used. Is done.

The organopolysiloxane having an epoxy group has a structure having a glycidyl group and an alicyclic epoxy group at a terminal and / or a side chain of a dimethylpolysiloxane skeleton. The viscosity of the preferred epoxy group-containing organopolysiloxane is not more than 500 cSt at 25 ° C. If the viscosity exceeds 500 cSt, the aggregation of the metal oxide fine powder becomes conspicuous at the time of processing, and it becomes difficult to uniformly treat the metal oxide fine powder.

Specific examples of the epoxy compound used in the present invention are as follows.

As the silane coupling agent, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane , Β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3
4-epoxycyclohexyl) ethyltriethoxysilane and the like.

Further, as the organopolysiloxane,
Shin-Etsu Chemical KF-101, KF-102, KF
-103, KF-105, X-22-163A, X-2
2-163B, X-22-169AS, X-22-16
9B, etc .; SF manufactured by Dow Corning Toray Silicone Co., Ltd.
8411, SF8413, SF8421, etc .; TSF4730, TSF4731, TSL9 manufactured by Toshiba Silicone Co., Ltd.
946, TSL9986, TSL9906 and the like.

On the other hand, as the alkylsilazane, those represented by the general formula (I) or (II) are preferably used. In the general formulas (I) and (II), R is particularly preferably An alkyl group having 1 or 2 carbon atoms is preferable, and specific examples of the compound represented by the general formula (I) include hexamethyldisilazane and the like, wherein R is partially substituted with a hydrogen atom. Examples thereof include tetramethyldisilazane and the like, and those substituted with a vinyl group include divinyltetramethyldisilazane. Examples of the compound represented by the general formula (II) include hexamethylcyclotrisilazane, octamethylcyclotetrasilazane, and the like.

The amount of the epoxy compound and the alkylsilazane to be added to the metal oxide fine powder is usually 0.1 to 100 parts by weight of the metal oxide fine powder.
1 to 50 parts by weight, preferably 1 to 20 parts by weight, and 0.1 to 100 parts by weight, preferably 1 to 100 parts by weight of alkylsilazane.
５０50 parts by weight.

As described above, when the surface treatment with the epoxy compound is carried out, the epoxy group on the surface of the metal oxide fine powder is ring-opened with the decomposition product of the alkylsilazane by using the alkylsilazane in combination to form the amino group and the alkylsilyl group. Groups can be introduced.

Of these, the amount of amino groups introduced is 30 to 3000 ppm in terms of the N amount of the obtained hydrophobic metal oxide fine powder.
It is preferred that it is about. When the N amount is less than 30 ppm, the effect of the present invention by introducing an amino group cannot be obtained. Further, it is technically difficult to introduce a large amount of amino group such that the N amount exceeds 3000 ppm.

The ratio of the alkylsilyl group to be introduced into the epoxy group is 0.1 to the amount of the epoxy group of the epoxy compound introduced into the obtained hydrophobic metal oxide fine powder.
It is preferably one or more. When the introduction ratio is less than 0.1, the improvement effect of the present invention by introducing an alkylsilyl group cannot be obtained.

With respect to the physical properties of the hydrophobic metal oxide fine powder of the present invention produced as described above, the charge amount to the iron powder carrier is -400 to +400 μC / g, and the charge amount can be freely controlled. , Negative charge, zero charge,
Positive chargeability can be selected, and its strength can be freely changed.

The hydrophobicity measured by the transmittance method is at least 60%, preferably at least 70%. By having a hydrophobicity of 60% or more, moisture adsorption is prevented, the fluctuation of charging due to the environment is small, and excellent performance is exhibited even for long-term use. If the hydrophobicity is less than 60%, moisture adsorption occurs, fluctuations in charging occur, and inconvenience is caused by long-term use.

The charge amount and hydrophobicity of the hydrophobic metal oxide fine powder are measured by the following methods.

[Measurement Method of Charge Amount] In a 75 mL glass container, 50 g of iron powder carrier and 0.1 fine powder of hydrophobic metal oxide were added.
g of the powdered metal, covered with the lid, and shaken for 5 minutes with a turbula mixer. Then, 0.1 g of the iron powder carrier mixed with the hydrophobic metal oxide fine powder was collected, and a blow-off charge amount measuring device (TB, manufactured by Toshiba Chemical Co., Ltd.) -200 type), and the value after nitrogen blowing for 1 minute is defined as the charge amount.

[Method of Measuring Hydrophobicity] 1 g of a sample is 200 mL
, And 100 mL of pure water is added thereto, stoppered, and shaken with a Turbula mixer for 10 minutes. After shaking, let stand for 10 minutes. After standing, the lower 20-30m
After extracting L from the funnel, the mixed solution of the lower layer was
The sample is taken out into an m quartz cell and subjected to a colorimeter using pure water as a blank, and the transmittance at 500 nm is defined as the hydrophobicity.

The electrophotographic toner composition of the present invention contains such a hydrophobic metal oxide fine powder of the present invention, and the content thereof is such that the obtained developer exhibits the above-mentioned property improvement. The amount is not particularly limited, but is preferably 0.01 to 5.0% by weight, and can be added to the toner by a known method.

When the content of the hydrophobic metal oxide fine powder in the electrophotographic toner composition is less than 0.01% by weight, the effect of adding the hydrophobic metal oxide fine powder to improve the fluidity and the charge can be improved. The effect of stabilizing sex cannot be obtained sufficiently. On the other hand, if the content of the hydrophobic metal oxide fine powder exceeds 5.0% by weight, the behavior of the hydrophobic metal oxide fine powder alone increases, which causes a problem in image and cleaning properties.

The toner generally contains a small amount of a pigment, a charge controlling agent, and an external additive in addition to a thermoplastic resin. In the present invention, as long as the above-mentioned hydrophobic metal oxide fine powder is blended, the other components may be the same as those in the related art, and may be either a magnetic or non-magnetic one-component toner or a two-component toner. Also,
The toner may be either a negatively chargeable toner or a positively chargeable toner, and may be either monochrome or color.

In the electrophotographic toner composition of the present invention, the hydrophobic metal oxide fine powder as an external additive is not limited to being used alone, but may be used in combination with another metal oxide fine powder. May be. For example, using the hydrophobic metal oxide fine powder in combination with other surface-modified dry silica fine powder, surface-modified dry titanium oxide fine powder, surface-modified wet titanium oxide fine powder, or the like. Can be.

[0044]

The present invention will be described more specifically below with reference to examples and comparative examples.

In the following, the methods for measuring the charge amount and the hydrophobicity of the hydrophobic metal oxide fine powder are as described above. However, the fluidity of the electrophotographic toner composition, the environmental stability of the charge amount, and The evaluation method of the image characteristics is as follows.

[Evaluation Method of Fluidity] An electrophotographic toner composition obtained by stirring and mixing 0.4 g of a hydrophobic metal oxide fine powder and 40 g of a positive or negatively chargeable 7 μm toner with a mixer was mixed with a powder tester (PT-N type). Hosokawa Micron Corporation)
At 150 μm, 75 μm and 45 μm while vibrating the screen, sequentially sieving, 150 μm,
The ratio of passing through all the 75 μm and 45 μm screens was defined as the 45 μm screen passage ratio, and a value of 80% or more was regarded as good fluidity.

[Evaluation Method of Environmental Stability of Charge Amount]
2 g of an electrophotographic toner composition in which 0.4 g of a hydrophobic metal oxide fine powder and 40 g of a positively or negatively chargeable 7 μm toner were stirred and mixed in a glass container of L with a mixer, and an iron powder carrier 4
Add 8 g and leave under HH and LL environment for 24 hours. Here, under the HH environment, an atmosphere of 40 ° C. and 85% is defined as LL.
The environment means an atmosphere of 10 ° C. and 20%.
The mixture of the electrophotographic toner composition and the iron powder carrier left for 24 hours in the HH and LL environments was shaken with a turbula mixer for 5 minutes, and then the iron powder carrier mixed with the electrophotographic toner composition was added to 0.1%. 2 g was collected and measured with a blow-off charge amount measuring device (TB-200, manufactured by Toshiba Chemical Corporation).
The value after the nitrogen blow for 5 minutes is defined as the charge amount of the electrophotographic toner composition, and the difference between the charge amounts of the electrophotographic toner composition left for 24 hours in an HH and LL environment was determined.
Those having a value of μC / g or less were determined to be stable without being affected by environmental differences.

[Evaluation Method of Image Characteristics] After printing 50,000 sheets or more using a commercially available copying machine, image characteristics (fogging, image density, etc.) were observed.

Example 1 100 parts by weight of fumed silica (trade name “Aerosil 200”, specific surface area 200 m ² / g, manufactured by Nippon Aerosil Co., Ltd.) was placed in a mixer, and the mixture was stirred under a nitrogen atmosphere with stirring. Sidoxypropyltrimethoxysilane 3 parts by weight, hexamethyldisilazane 2
0 parts by weight was added dropwise, and the mixture was heated and stirred at 150 ° C. for 1 hour, and then cooled.

The obtained fine powder has a triboelectric charge of -300 μC / g with an iron powder carrier and a hydrophobicity of 95 according to a transmittance method.
%, The BET specific surface area was 140 m ² / g, the carbon amount was 2.9% by weight, the N amount was 300 ppm, and the introduction ratio of the alkylsilyl group to the introduced epoxy group was 0.27.

The triboelectric charge after leaving the fine powder for 24 hours under LL conditions is −320 μC / g, and the triboelectric charge after leaving for 24 hours under HH conditions is +270 μC / g.
g, and HH / LL was 0.84, resulting in a small difference depending on the environment.

When the fluidity of a toner composition obtained by mixing this fine powder with a negatively-chargeable 7 μm toner was measured, a good fluidity was obtained with a transmittance of 92% through a 45 μ screen. Further, the toner composition and the iron powder carrier were mixed for 24 hours.
When left under L and HH conditions and triboelectrically charged,
The difference in charge amount between LL and HH was as small as 2 μC / g, and the charge amount was excellent in environmental stability.

When printing was carried out on 50,000 sheets or more using a commercially available copying machine, the image characteristics were good.

Example 2 100 parts by weight of fumed silica (trade name "Aerosil 200", specific surface area 200 m ² / g, manufactured by Nippon Aerosil Co., Ltd.) was put into a mixer, and β- ( 10 parts by weight of 3,4-epoxycyclohexyl) ethyltrimethoxysilane and 20 parts by weight of hexamethylcyclotrisilazane were added dropwise.
The mixture was heated and stirred at 50 ° C. for 1 hour, and then cooled.

The obtained fine powder had a triboelectric charge of +200 μC / g with an iron powder carrier and a hydrophobicity of 8 by a transmittance method.
8%, BET specific surface area 130 m ² / g, carbon content 5.5 wt%, N content 1900 ppm, introduction ratio of alkylsilyl group to epoxy group introduced 0.42
showed that.

The triboelectric charge after leaving the fine powder for 24 hours under LL conditions is +220 μC / g, and the triboelectric charge after leaving for 24 hours under HH conditions is +170 μC / g.
g, and HH / LL was 0.77, which was a small difference depending on the environment.

When the fluidity of a toner composition in which this fine powder was mixed with a positively chargeable 7 μm toner was measured, a good fluidity was obtained with a passage rate of 87% through a 45 μ screen. Further, the toner composition and the iron powder carrier were mixed for 24 hours.
When left under L and HH conditions and triboelectrically charged,
The difference in charge amount between LL and HH was as small as 4 μC / g, and the charge amount was excellent in environmental stability.

Further, when printing was carried out on 50,000 or more sheets using a commercially available copying machine, the image characteristics were good.

Example 3 100 parts by weight of ultrafine particle titania (trade name “titanium oxide P25”, specific surface area: 50 m ² / g, manufactured by Nippon Aerosil Co., Ltd.) was placed in a mixer, and both ends were stirred under a nitrogen atmosphere while stirring. Glycidyl-modified organopolysiloxane (trade name “KF105” Shin-Etsu Chemical Co., Ltd.)
5 parts by weight, 10 parts by weight of hexamethyldisilazane, n
20 parts by weight of hexane was added dropwise, and the mixture was heated and stirred at 200 ° C. for 1 hour, and the solvent was further removed.

The obtained fine powder has a triboelectric charge of +50 μC / g with an iron powder carrier and a hydrophobicity of 75 by a transmittance method.
%, The BET specific surface area is 35 m ² / g, and the carbon amount is 2.
8% by weight, N content was 350 ppm, and the introduction ratio of the alkylsilyl group to the introduced epoxy group was 0.25.

The triboelectric charge after leaving the fine powder for 24 hours under LL conditions shows +57 C / g, the triboelectric charge after leaving for 24 hours under HH conditions shows +44 μC / g, and HH / LL Was 0.77, and the difference between the environments was small.

When the fluidity of a toner composition obtained by mixing this fine powder with a positively-chargeable 7 μm toner was measured, a good fluidity was obtained with a passage rate of 45% through a 45 μ screen. Further, the toner composition and the iron powder carrier were subjected to LL for 24 hours.
And under HH conditions and triboelectrically charged, L
The difference between the charge amounts of L and HH was as small as 5 μC / g, and the charge amount was excellent in environmental stability.

Further, when printing was carried out on 50,000 or more sheets using a commercially available copying machine, the image characteristics were good.

Example 4 100 parts by weight of ultrafine alumina particles (trade name “Aluminum oxide C”, specific surface area: 100 m ² / g, manufactured by Degussa Co., Ltd.) were put into a mixer, and the mixture was stirred under a nitrogen atmosphere with glycidyl-modified organo at both ends. Polysiloxane (trade name “KF105” manufactured by Shin-Etsu Chemical Co., Ltd.) 3
Parts by weight, 20 parts by weight of hexamethyldisilazane, and 20 parts by weight of n-hexane were added dropwise, and the mixture was heated and stirred at 200 ° C. for 1 hour, and the solvent was further removed.

The obtained fine powder had a triboelectric charge of −25 μC / g with an iron powder carrier and a hydrophobicity of 85 by a transmittance method.
%, The BET specific surface area is 75 m ² / g, and the carbon amount is 4.
The content of N was 150 ppm, the content of N was 150 ppm, and the introduction ratio of the alkylsilyl group to the introduced epoxy group was 0.22.

The triboelectric charge after leaving the fine powder for 24 hours under LL conditions showed -29 μC / g, and the triboelectric charge after leaving for 24 hours under HH conditions showed -21 μC / g. / LL was 0.72, which was a small difference depending on the environment.

When the fluidity of a toner composition obtained by mixing this fine powder with a negatively-chargeable 7 μm toner was measured, a good fluidity was obtained with a transmittance of 45% through a 45 μ screen. Further, the toner composition and the iron powder carrier were mixed for 24 hours.
When left under L and HH conditions and triboelectrically charged,
The difference in charge amount between LL and HH was as small as 4 μC / g, and the charge amount was excellent in environmental stability.

When printing was carried out on 50,000 sheets or more using a commercially available copying machine, the image characteristics were good.

Comparative Example 1 100 parts by weight of fumed silica (trade name “Aerosil 200”, specific surface area: 200 m ² / g, manufactured by Nippon Aerosil Co., Ltd.) was placed in a mixer, and the mixture was stirred under a nitrogen atmosphere with γ-grid. 3 parts by weight of sidoxypropyltrimethoxysilane and 1.5 parts by weight of 1,3-diaminopropane were added dropwise, and the mixture was heated and stirred at 150 ° C. for 1 hour,
Then it was cooled.

The obtained fine powder has a triboelectric charge of -150 μC / g with an iron powder carrier and a hydrophobicity of 0 according to the transmittance method.
%, The BET specific surface area was 165 m ² / g, and the carbon amount was 1.5% by weight.

The triboelectric charge after leaving the fine powder for 24 hours under LL conditions is -200 μC / g, and the triboelectric charge after being left for 24 hours under HH conditions is -70 μC / g.
And HH / LL was 0.35, which resulted in a large influence of the environment.

When the fluidity of a toner composition in which this fine powder was mixed with a negatively-chargeable 7 μm toner was measured, the passing rate through a 45 μ screen was 68%, indicating that good fluidity could not be obtained. Further, when the toner composition and the iron powder carrier were allowed to stand under LL and HH conditions for 24 hours and triboelectrically charged, the difference in charge amount between LL and HH was as large as 12 μC / g, and the hydrophobicity was low. Due to the effect of the adsorbed moisture, the difference due to the environmental difference was large.

Further, when 1,000 sheets were printed using a commercially available copying machine, fog occurred in the image characteristics.

Comparative Example 2 100 parts by weight of fumed silica (trade name “Aerosil 200”, specific surface area 200 m ² / g, manufactured by Nippon Aerosil Co., Ltd.) was placed in a mixer, and γ-amino was stirred under a nitrogen atmosphere while stirring. 10 parts by weight of propyltriethoxysilane and 15 parts by weight of hexamethyldisilazane were added dropwise, heated and stirred at 150 ° C. for 1 hour, and then cooled.

The obtained fine powder has a triboelectric charge of +500 μC / g with an iron powder carrier and a hydrophobicity of 2 according to the transmittance method.
0%, the BET specific surface area was 140 m ² / g, and the carbon amount was 2.8% by weight.

The triboelectric charge after leaving this fine powder for 24 hours under LL conditions is +520 μC / g, and the triboelectric charge after leaving for 24 hours under HH conditions is +280 μC / g.
g, and HH / LL was 0.54, which was a result largely influenced by the environment.

When the fluidity of a toner composition in which this fine powder was mixed with a positively-chargeable 7 μm toner was measured, good fluidity was not obtained because the passage rate through a 45 μ screen was 73%. Further, when the toner composition and the iron powder carrier were allowed to stand under LL and HH conditions for 24 hours and were subjected to frictional charging, the difference in charge amount between LL and HH was as large as 9 μC / g and the hydrophobicity was low. Therefore, the difference due to the environmental difference was large due to the influence of the adsorbed moisture.

Further, when 10,000 sheets were printed using a commercially available copying machine, the image characteristics became lighter in image density.

Comparative Example 3 100 parts by weight of ultrafine titania (trade name “titanium oxide P25”, specific surface area: 50 m ² / g, manufactured by Nippon Aerosil Co., Ltd.) was put into a mixer, and both ends were stirred under a nitrogen atmosphere while stirring. Glycidyl-modified organopolysiloxane (trade name “KF105” Shin-Etsu Chemical Co., Ltd.)
5 parts by weight, 1,3-diaminopropane 2 parts by weight, n
20 parts by weight of hexane was added dropwise, and the mixture was stirred with heating at 200 ° C. for 1 hour, the solvent was further removed, and then the mixture was cooled.

The obtained fine powder had a triboelectric charge of +30 μC / g with an iron powder carrier and a hydrophobicity of 30 by a transmittance method.
%, The BET specific surface area is 35 m ² / g, and the carbon amount is 2.
3% by weight.

The triboelectric charge after leaving the fine powder for 24 hours under the LL condition shows +37 μC / g, the triboelectric charge after leaving for 24 hours under the HH condition shows +18 μC / g, and HH / LL Shows 0.48, which is a result largely influenced by the environment.

When the fluidity of a toner composition in which this fine powder was mixed with a positively-chargeable 7 μm toner was measured, a good fluidity was not obtained because the passage rate through a 45 μ screen was 61%. Further, when the toner composition and the iron powder carrier were allowed to stand under LL and HH conditions for 24 hours and triboelectrically charged, the difference in charge amount between LL and HH was as large as 13 μC / g and the hydrophobicity was low. Due to the effect of the adsorbed moisture, the difference due to the environmental difference was large.

Further, when 1,000 sheets were printed using a commercially available copying machine, fogging occurred in the image characteristics.

Comparative Example 4 100 parts by weight of ultrafine alumina (trade name “Aluminum oxide C”, specific surface area: 100 m ² / g, manufactured by Degussa Co., Ltd.) was placed in a mixer, and the mixture was stirred under a nitrogen atmosphere with glycidyl-modified organo at both ends. Polysiloxane (trade name “KF105” manufactured by Shin-Etsu Chemical Co., Ltd.) 3
Parts by weight, 1 part by weight of dibutylaminopropanediamine, n
20 parts by weight of hexane was added dropwise, and the mixture was heated and stirred at 200 ° C. for 1 hour, and the solvent was further removed.

The obtained fine powder had a triboelectric charge of −40 μC / g with an iron powder carrier and a hydrophobicity of 15 by a transmittance method.
%, The BET specific surface area is 85 m ² / g, and the carbon amount is 1.
9% by weight.

The triboelectric charge after leaving this fine powder for 24 hours under LL conditions showed -53 μC / g, and the triboelectric charge after leaving for 24 hours under HH conditions showed -29 μC / g. / LL was 0.55, which resulted in a large influence of the environment.

When the fluidity of a toner composition in which this fine powder was mixed with a negatively-chargeable 7 μm toner was measured, a good fluidity was not obtained because the passage rate through a 45 μ screen was 65%. When the toner composition and the iron powder carrier were allowed to stand for 24 hours under LL and HH conditions and subjected to frictional charging, the difference in charge amount between LL and HH was as large as 11 μC / g and the hydrophobicity was low. Therefore, the difference due to the environmental difference was large due to the influence of the adsorbed moisture.

Further, when 3000 sheets were printed using a commercially available copying machine, fogging occurred in the image characteristics.

[0089]

As described in detail above, the hydrophobic metal oxide fine powder of the present invention is hydrophobic, has a controlled charge, and has little charge fluctuation. In addition, it is chemically stable with little change with time.

Therefore, the hydrophobic metal oxide fine powder of the present invention is excellent in fluidity, chargeability and durability in electrophotographic toner, can improve the stability over time, and can be used as a liquid resin. When used, since it has a functional group on its surface, it has excellent compatibility with the filler and can improve mechanical strength and viscosity.

The toner composition for electrophotography of the present invention is blended with the hydrophobic metal oxide fine powder of the present invention which has such high hydrophobicity and whose charge is controlled. Therefore, the toner exhibits high charge stability and high fluidity over a long period of time as an electrophotographic toner. For this reason, there is no problem of a decrease in image density, the image characteristics are excellent, and good cleaning properties are exhibited.

Continued on the front page (72) Inventor Hiroshu Jino 3 Mitacho, Yokkaichi-shi, Mie Prefecture Inside Yokkaichi Plant of Aerosil Japan Co., Ltd.

Claims (9)

[Claims] 1. A hydrophobic property, wherein an amino group and an alkylsilyl group are introduced into an epoxy group on the surface of the metal oxide fine powder by subjecting the metal oxide fine powder to a surface treatment with an epoxy compound and an alkylsilazane. Metal oxide fine powder. 2. The hydrophobic metal oxide fine powder according to claim 1, wherein the metal oxide fine powder is silica, titania or alumina. 3. The hydrophobic metal oxide fine particle according to claim 1, wherein the epoxy compound is a silane coupling agent having one or more epoxy groups in a molecule and / or an organopolysiloxane. Powder. 4. An alkylsilazane represented by the following general formula (I):
The hydrophobic metal oxide fine powder according to any one of claims 1 to 3, characterized in that: R ₃ Si (NHSiR ₂ ) _n NHSiR ₃ (I) (In the general formula (I), R represents an alkyl group having 1 to 3 carbon atoms, and some of the substituents are other atoms such as a hydrogen atom or a vinyl group. It may be a substituent, and n represents an integer of 0 to 8.) 5. An alkylsilazane represented by the following general formula (II)
The hydrophobic metal oxide fine powder according to any one of claims 1 to 3, characterized in that: Embedded image (In the general formula (II), R represents an alkyl group having 1 to 3 carbon atoms, some of the substituents may be a hydrogen atom or another substituent such as a vinyl group, and m represents 3 to 6 Indicates an integer.) 6. The method according to claim 1, wherein the hydrophobicity is determined by a transmittance method.
A value of 0% or more is shown.
The hydrophobic metal oxide fine powder according to any one of the above. 7. The amount of triboelectric charge on iron powder is -400 to +
The hydrophobic metal oxide fine powder according to any one of claims 1 to 6, wherein the fine powder is 400 µC / g. 8. A hydrophobic method characterized in that an amino group and an alkylsilyl group are introduced into an epoxy group on the surface of the metal oxide fine powder by subjecting the metal oxide fine powder to a surface treatment with an epoxy compound and an alkylsilazane. Production method of functional metal oxide fine powder. 9. A toner composition for electrophotography, comprising the hydrophobic metal oxide fine powder according to claim 1. Description: