JPH11124464A - Hydrophobic metal oxide fine powder and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject fine powder having high hydrophobic property, capable of arbitrarily controlling electron charge amount according to treating conditions by treating metal oxide fine powder with a specific surface treating agent. SOLUTION: This fine powder is obtained by treating (A) metal oxide fine powder (preferably silica, titania or alumina, preferably having 10-400 m<2> /g specific surface area) with (B) an epoxy group-containing silane (e.g. θ- glycidoxypropyltrimethoxysilane), (C) an amino group-containing organic compound (preferably monoamine, diamine or the like) and (D) both terminal reactive groups-blocked type organopolysiloxane, preferably represented by the formula [R is methyl or ethyl; X is a halogen or the like; (n) is an integer of 15-500]. Furthermore, total amount of components B to D used is preferably 2-100 wt.% based on the component A to be treated. As a result, the fine powder hardly causes change in electron charge and it can be expected that the powder keeps excellent performance over a long period.

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. Improvement of powder flowability, prevention of caking,
The present invention relates to a surface-modified metal fine powder added for the purpose of charge adjustment and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Metal oxide powders such as silica used as an organic liquid thickener and a reinforcing filler are usually treated with an alkylsilane or an organopolysiloxane to make the surface hydrophobic. I have. For example, JP
No. -14900 describes that an oxide fine powder is treated with an alkyl halide silane.
No. 2641 discloses that an oxide fine powder is treated with an organopolysiloxane. In the powder system, fine silica, surface-treated metal oxide powder obtained by treating the surface of metal oxide powder such as titania and alumina with an organic substance is used in electrophotography such as copying machines, laser printers, and plain paper facsimile machines. Widely used as a toner fluidity improver.

[0003] In such applications, triboelectric charging of iron or iron oxide as a carrier is one of the important powder characteristics. Generally, a negatively charged toner uses a negatively charged external additive, and a positively charged toner often uses a positively charged external additive. Metal oxide powder is used as a positively charged toner fluidity improver. Is generally used. As such a metal oxide powder, a powder having an amino group on its surface is known. For example, JP-A-62-52561 discloses that silica produced by a gas phase method is treated with an epoxy group-containing silane and then treated with an amine. JP-A-6-83099 describes that a metal oxide powder is heat-treated with an epoxy-containing modified silicone oil and further treated with an amino-containing organic compound.

[0004]

In recent years, toners having a size of 10 μm have been developed.
As the particle size is reduced from m to 7 μm, there is a problem that the fluidity of the toner decreases. To improve this, the amount of the toner external additive added is larger than in the past. Additives have come to greatly affect the chargeability of toner. In particular, charging fluctuation due to the environment has become a problem, and in order to prevent this, a highly hydrophobic toner external additive has been demanded. However, the above-mentioned conventional metal oxide powder having an amino group on the surface has a high affinity for water, and therefore, there is a problem that charge fluctuations due to environmental fluctuations and the like and aggregation easily occur.

In other words, simply treating a metal oxide fine powder with an epoxy group-containing silane or an amino group-containing organic compound as in the prior art is insufficient in hydrophobicity, causing charge fluctuation due to long-term use or moisture absorption. However, the fluidity also decreases. Also, when the metal oxide fine powder is treated with an epoxy group-containing modified silicone or an amino group-containing organic compound, the hydrophobicity is still insufficient, and charge fluctuation occurs due to long-term use or moisture absorption, and the fluidity decreases. .

The present invention has been made to solve the above-mentioned problems in the conventional metal oxide powder, and provides a surface-modified metal oxide fine powder having high hydrophobicity and controlled chargeability, and a method for producing the same. With the goal.

[0007]

That is, the present invention relates to a metal oxide fine powder having the following constitution. (1) A hydrophobic metal oxide fine powder obtained by treating a metal oxide fine powder with an epoxy group-containing silane, an amino group-containing organic compound, and an organopolysiloxane having a terminal-reactive group.

[0008] The metal oxide fine powder of the present invention includes the following aspects. (2) A hydrophobic metal oxide fine powder having a hydrophobicity of 70% or more as measured by a transmittance method. (3) A hydrophobic metal oxide fine powder having a specific surface area of 10 to 400 m ² / g. (4) A hydrophobic metal oxide fine powder in which the metal oxide fine powder is silica, titania or alumina. (5) Both ends of the reactive group-blocked organopolysiloxane are represented by the following general formula: (Wherein, R is an alkyl group comprising a methyl group or an ethyl group, and may be partially substituted with an alkyl group containing any one of a functional group containing a vinyl group, a phenyl group, and an amino group; Is a halogen atom, a hydroxyl group or an alkoxy group, and n is an integer of 15 to 500), and the hydrophobic metal oxide fine powder according to any one of claims 1 to 4. (6) Hydrophobic metal oxide fine powder treated with 1 to 50% by weight of a metal oxide fine powder of an organopolysiloxane having a terminal-reactive group.

The present invention also relates to the following method for producing a hydrophobic metal oxide fine powder. (7) A metal oxide fine powder having a specific surface area of 10 to 400 m ² / g is mixed with an epoxy group-containing silane, an amino group-containing organic compound and an organopolysiloxane blocked at both ends with a reactive group, followed by heat treatment. Of producing a fine hydrophobic metal oxide powder.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. The hydrophobic metal oxide fine powder of the present invention is obtained by treating a metal oxide fine powder with an epoxy group-containing silane, an amino group-containing organic compound, and an organopolysiloxane having a capped terminal-reactive group. That is, according to the present invention, by such treatment, an epoxy group is opened, an amino group is introduced therein, and an organopolysiloxane having a functional group reactive with a hydroxyl group generated by ring opening or a hydroxyl group of a metal oxide. This is a metal oxide fine powder having high hydrophobicity and controlled chargeability by reacting siloxane.

The type of the metal oxide fine powder according to the present invention is not limited. Generally, silica, titania, alumina and the like are preferably used. These metal oxide fine powders include trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylalkoxysilane, dimethyldialkoxysilane, methyltrialkoxysilane, hexamethyldisilazane, various silicone oils and various silane coupling agents. May have been subjected to a hydrophobic treatment in advance.

The metal oxide fine powder of the present invention preferably has a specific surface area of generally 10 to 400 m ² / g when used as various additives and fillers. A metal oxide fine powder having the above specific surface area can be obtained by, for example, a gas phase high temperature thermal decomposition method of a metal halide compound.

In the present invention, an epoxy group-containing silane, an amino group-containing organic compound and an organopolysiloxane blocked at both ends are used as a surface treating agent for the metal oxide fine powder. Among them, the epoxy group-containing silane is, for example, a trialkoxysilane or dialkoxysilane having an epoxy group such as a glycidyl group or an epoxycyclohexyl group, and specific examples thereof are as follows. That is, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane,
γ-glycidoxypropylmethyldimethoxysilane, γ
-Glycidoxypropylmethyldiethoxysilane, β-
(3,4 epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4 epoxycyclohexyl) ethyltriethoxysilane and the like can be mentioned.

Further, as the amino group-containing organic compound,
Monoamines, diamines, triamines or tetramines are preferred. Specific examples include dimethylamine, diethylamine, dibutylamine, dimethylaminopropylamine, diethylaminopropylamine, dibutylaminopropylamine, diethylenetriamine, and triethylenetetramine.

As the organopolysiloxane having a reactive functional group at both ends (referred to as an organopolysiloxane having both ends reactive group-blocked), those represented by the following general formula (1) are preferably used. In the formula, R is an alkyl group composed of a methyl group or an ethyl group, and may be partially substituted with an alkyl group containing any one of a vinyl group, a phenyl group, and a functional group containing an amino group; A halogen atom, a hydroxyl group or an alkoxy group,
n is the degree of polymerization of the siloxane bond.

The organopolysilixane of the above general formula has a halogen atom, a hydroxyl group or an alkoxy group at both ends of a siloxane bond, and both ends are blocked by these reactive groups. Therefore, the organopolysiloxane terminal reacts with the hydroxyl group generated by ring opening of the epoxy group and the hydroxyl group of the metal oxide via this reactive group to form a stable hydrophobic surface treatment layer, and the metal oxide fine powder is formed. Hydrophobic.

Preferred organopolysiloxanes have a siloxane bond polymerization degree n of 15 to 50 in the above general formula.
0. If the degree of polymerization n is less than 15, the siloxane has a small molecular weight and thus is easily volatilized, making it difficult to increase the degree of hydrophobicity. On the other hand, if the degree of polymerization n exceeds 500, the agglomeration of the powders becomes large, and the properties as a fine powder are lost, which is not preferable.

The amount of the epoxy group-containing silane, amino group-containing organic compound and organopolysiloxane having a terminal-reactive group blocked is 2 to 100% by weight based on the metal oxide fine powder to be treated. Is preferable. Here, the addition amount of the amino group-containing organic compound is suitably equal to or less than the addition amount of the epoxy group-containing silane. If it is longer than that, an amino group-containing organic compound which does not react with the epoxy group is released, which is not preferable. Also,
The amount of the organopolysiloxane blocked at both ends reactive groups is preferably 1 to 50% by weight based on the metal oxide fine powder to be treated. If the amount is less than 1% by weight, the effect of the treatment is not clear, and if it exceeds 50% by weight, the effect is saturated.

The above-mentioned metal oxide fine powder, preferably a metal oxide fine powder having a specific surface area of 10 to 400 m ² / g, is mixed with the above-mentioned predetermined amount of an epoxy group-containing silane, an amino group-containing organic compound and an organo-blocked organo-terminal-blocking type. The desired hydrophobic metal oxide fine powder can be obtained by mixing with polysiloxane and subjecting to heat treatment. In the present invention, a known method can be used for the mixing and heating treatment method. That is, 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, stirred under a nitrogen atmosphere, and an epoxy group-containing silane, an amino group-containing organic compound, After dropping or spraying a predetermined amount of the blocked organopolysiloxane to the above-mentioned metal oxide fine powder together with a solvent, if necessary, and sufficiently dispersing the same, a temperature of 50 ° C. or more, preferably 150 ° C. or more, is used. 5 hours,
Preferably, stirring and surface treatment are carried out for 1 to 2 hours, and solvent and by-products are removed by evaporation, followed by cooling to obtain a uniform surface-modified metal oxide fine powder.

The surface-modified metal oxide of the present invention obtained by the above-mentioned surface treatment has high hydrophobicity, and the charge amount can be arbitrarily adjusted depending on the treatment conditions. That is, negative charging property, zero charging property, and positive charging property can be selected, and the strength can be freely changed. Specifically, for example, a charge amount of −700 to +700 μC / g with respect to the iron powder carrier is exhibited, and the hydrophobicity according to the transmittance method can be increased to 70% or more.

Since the surface-modified metal oxide of the present invention can have a hydrophobicity of 70% or more, it hardly adsorbs water, and therefore has very little fluctuation in charging due to the environment, and exhibits excellent performance over a long period of time. By the way, if the hydrophobicity is smaller than 70%, a fluctuation in electrification due to moisture adsorption occurs, which causes inconvenience in long-term use.

[0022]

As described above, the hydrophobic metal oxide fine powder of the present invention has high hydrophobicity and is controlled in charge, so that the charge fluctuation is small. In addition, it is chemically stable with little change with time. Therefore, when the hydrophobic metal oxide fine powder of the present invention is used for an electrophotographic toner, fluidity, chargeability and durability can be improved, and stability over time can be improved. Further, when used for a liquid resin, since it has a functional group on its surface, it has excellent compatibility with a filler and can improve mechanical strength and viscosity.

[0023]

Examples and Comparative Examples Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In each example, the charge amount and the hydrophobicity of the surface-modified metal oxide were measured by the following methods. (1) Charge amount Put 50 g of iron powder carrier and 0.1 g of surface-modified metal oxide powder in a glass container (75 ml), cover and shake for 5 minutes with a turbula mixer. 0.1 g of an iron powder carrier in which powder is mixed is collected, and the value after nitrogen blowing for 1 minute with a blow-off charge amount measuring device (TB-200, manufactured by Toshiba Chemical Corporation) is defined as the charge amount. (2) 1 g of a hydrophobic sample was weighed into a separating funnel (200 ml), 100 ml of pure water was added thereto, stoppered, and 10 g was added with a turbuler mixer.
After shaking for 10 minutes, let stand for 10 minutes. After standing still, the lower layer 2
After withdrawing 0 to 30 ml from the funnel, the lower mixed solution is dispensed into a quartz cell (10 mm) and subjected to colorimetry using pure water as a blank, and the transmittance at 500 nm is defined as the hydrophobicity.

Example 1 100 parts by weight of fumed silica (specific surface area: 200 m ² / g, manufactured by Nippon Aerosil Co., Ltd .: Aerosil 200) was put into a mixer, and the mixture was stirred under an atmosphere of nitrogen while stirring with an epoxy group-containing silane (available from Shin-Etsu Chemical Co., Ltd.) : KBM403), 1.6 parts by weight of diethylaminopropylamine, 20 parts by weight of α, ω-dihydroxydimethylpolysiloxane (40cs) and a mixture of 50 parts by weight of normal hexane were added dropwise. ° C
For 1 hour, and the mixture was further cooled by removing the solvent to obtain a surface-modified silica powder. This silica powder had a triboelectric charge of +300 μC / g with an iron powder carrier, a hydrophobicity of 95% by a transmittance method, a BET specific surface area of 100 m ² / g, and a carbon content of 7.0% by weight. This silica powder is
The amount of triboelectric charge after leaving for 48 hours at low temperature and low humidity (LL) of 20 ° C. and 20% is +340 μC / g;
After being left under high temperature and high humidity (HH) for 48 hours, the triboelectric charge amount was +250 μC / g, and the charging ratio (HH / LL) depending on the environment was 0.74. Further, 0.5% by weight of this silica powder was added to a 7 μm positively chargeable toner, and printing was performed on 20,000 or more sheets using a commercial copying machine. The image characteristics were good without fogging. Further, 5% by weight of this fine powder was added to an epoxy resin (trade name: Ejicoat 828), kneaded with three rolls, and the viscosity was measured with an E-type viscometer.
(2.5 rpm), 41 Pas (20 rpm), thixotropic index (TI)
Was 2.2. To this, triethylenetetramine was added as a curing agent, and the adhesive strength measured according to JIS K 6850 was 70 kgf / cm ² . All of these evaluation results showed a significant improvement compared to Comparative Example 1.

Comparative Example 1 A surface-modified silica powder was prepared in the same manner as in Example 1 except that α, ω-dihydroxydimethylpolysiloxane (organopolysiloxane having both terminal reactive groups blocked) was not used. I got This silica powder had a triboelectric charge of +50 μC / g with an iron powder carrier, a hydrophobicity of 10% by a transmittance method, a BET specific surface area of 170 m ² / g, and a carbon content of 1.8% by weight. This silica powder is
The amount of triboelectric charge after standing for 48 hours under L conditions is +100
μC / g, the triboelectric charge after leaving for 48 hours under the HH condition shows +20 μC / g, and the charge ratio (HH / LL) is 0.2.
20. When 0.5% by weight of this silica powder was added to a 7 μm positively chargeable toner, and a commercial copying machine was used to print 1,000 sheets, image characteristics fogged. Further, 5% by weight of this fine powder was added to an epoxy resin (trade name: Ehjicoat 828) and kneaded with three rolls, and the viscosity was measured with an E-type viscometer. 31Pa ・ s (20rp
m), the thixotropic index (TI) was 1.0. Triethylenetetramine is added as a curing agent to this, and JIS K
Adhesive strength measured according to 6850 is 60 kgf / cm ²
Met.

Example 2 100 parts by weight of fumed silica (specific surface area: 50 m ² / g, manufactured by Nippon Aerosil Co., Ltd .: Aerosil 50) was put into a mixer, and the mixture was stirred under a nitrogen atmosphere while stirring to obtain an epoxy group-containing silane (Shin-Etsu Chemical Co., Ltd.). : KBM403), 0.7 part by weight of dibutylaminopropylamine, 10 parts by weight of α, ω-dihydroxydimethylpolysiloxane (40cs) and diluting with 20 parts by weight of normal hexane are added dropwise. Then, the mixture was heated and stirred at 200 ° C. for 1 hour, and the solvent was further removed and cooled to obtain a surface-modified silica powder. The silica powder had a triboelectric charge of -200 μC / g with an iron powder carrier, a hydrophobicity of 97% by a transmittance method, a BET specific surface area of 30 m ² / g, and a carbon amount of 3.3% by weight. In addition, this silica powder is
The amount of triboelectric charge after standing for 48 hours under the L condition was -250.
It was μC / g, the triboelectric charge after being left for 48 hours under HH conditions showed −170 μC / g, and the charging ratio (HH / LL) was 0.68. Further, 0.5% by weight of this silica powder was added to a 7 μm negatively chargeable toner, and printing was performed on 20,000 or more sheets using a commercially available copying machine. The image characteristics were good without fogging. Further, 5% by weight of this fine powder was added to an epoxy resin (trade name: Ehjicoat 828), kneaded with a three-roll mill, and the viscosity was measured with an E-type viscometer.
(2.5 rpm), 39 Pas (20 rpm), thixotropic index (TI)
Was 1.8. To this, triethylenetetramine was added as a curing agent, and the adhesive strength measured according to JIS K 6850 was 55 kgf / cm ² . All of these evaluation results showed a significant improvement compared to Comparative Example 2.

Comparative Example 2 A surface-modified silica powder was prepared in the same manner as in Example 2 except that α, ω-dihydroxydimethylpolysiloxane (organopolysiloxane having both terminal reactive groups blocked) was not used. I got This silica powder had a triboelectric charge amount of −100 μC / g with an iron powder carrier, a hydrophobicity measured by a transmittance method of 10%, a BET specific surface area of 42 m ² / g, and a carbon amount of 0.4% by weight. This silica powder is
The amount of triboelectric charge after standing for 48 hours under the L condition was -150.
μC / g, the triboelectric charge after standing for 48 hours under HH conditions is −70 μC / g, and the charge ratio (HH / LL) is 0.3.
47. When 0.5% by weight of this silica powder was added to a 7 μm negatively chargeable toner and 700 sheets were printed using a commercially available copying machine, fogging occurred in image characteristics. Also,
This fine powder was added to an epoxy resin (trade name: Echicoat 828) in an amount of 5% by weight, kneaded with a three-roll mill, and the viscosity was measured with an E-type viscometer. The viscosity was 28 Pa · s (2.5 rpm), 27 Pa · s (20r
pm), the thixotropic index (TI) was 1.0. Triethylenetetramine is added as a curing agent to this, and JIS K
Adhesive strength measured according to 6850 is 50 kgf / cm ²
Met.

Example 3 100 parts by weight of fumed silica (specific surface area: 110 m ² / g, manufactured by Nippon Aerosil Co., Ltd .: Aerosil R972) was put into a mixer, and the mixture was stirred under a nitrogen atmosphere while stirring, under a nitrogen atmosphere. : KBM403), 5 parts by weight of dibutylaminopropylamine, 3.9 parts by weight of α, ω-dihydroxydimethylpolysiloxane (40cs) mixed with 10 parts by weight, and diluted with 30 parts by weight of normal hexane were added dropwise. The mixture was heated and stirred at 200 ° C. for 1 hour, and the solvent was further removed and cooled to obtain a surface-modified silica powder. This silica powder had a triboelectric charge of +430 μC / g with an iron powder carrier, a hydrophobicity of 95% by a transmittance method, a BET specific surface area of 80 m ² / g, and a carbon content of 6.0% by weight. In addition, this silica powder is
The amount of triboelectric charge after standing for 48 hours under the L condition is +450
μC / g, the triboelectric charge after standing under HH conditions for 48 hours was +395 μC / g, and the charge ratio (HH / LL) was 0.88. Further, 0.5% by weight of this silica powder was added to a 7 μm positively chargeable toner, and printing was performed on 20,000 or more sheets using a commercial copying machine. The image characteristics were good without fogging. Further, 5% by weight of this fine powder was added to an epoxy resin (trade name: Ejicoat 828), kneaded with three rolls, and the viscosity was measured with an E-type viscometer.
(2.5 rpm), 39 Pas (20 rpm), thixotropic index (TI)
Was 2.8. To this, triethylenetetramine was added as a curing agent, and the adhesive strength measured according to JIS K 6850 was 67 kgf / cm ² . All of these evaluation results showed a significant improvement compared to Comparative Example 3.

Comparative Example 3 In Example 3, epoxy group-containing silane and α, ω
-In place of dihydroxydimethylpolysiloxane (both terminal reactive group-blocked organopolysiloxane), epoxy-modified organopolysiloxane (FZ3745, manufactured by Nippon Unica Ltd.)
A surface-modified silica powder was obtained by performing the same treatments as in Example 3 except for using. This silica powder had a triboelectric charge of +400 μC / g with an iron powder carrier, a hydrophobicity of 65% by a transmittance method, a BET specific surface area of 85 m ² / g, and a carbon content of 5.0% by weight. The triboelectric charge after leaving the silica powder for 48 hours under LL conditions is +430 μC / g.
After left for 48 hours under HH conditions, the triboelectric charge amount was +300 μC / g, and the charge ratio (HH / LL) was 0.70. When 0.5% by weight of this silica powder was added to a 7 μm positively chargeable toner and 1000 sheets were printed using a commercially available copying machine, fogging occurred in the image characteristics. Further, 5% by weight of this fine powder was added to an epoxy resin (trade name: Ehjicoat 828) and kneaded with three rolls, and the viscosity was measured with an E-type viscometer. 39 Pas (20 rpm),
The thixotropy index (TI) was 2.0. To this, triethylenetetramine was added as a curing agent, and JIS K 6850
Was 60 kgf / cm ² .

Example 4 100 parts by weight of ultrafine titanium oxide (specific surface area: 50 m ² / g, manufactured by Nippon Aerosil Co., Ltd .: titanium oxide P25) was placed in a mixer, and the mixture was stirred under a nitrogen atmosphere while stirring with an epoxy group-containing silane (Shin-Etsu Chemical Co., Ltd.). Company: KBM403) (2 parts by weight), dibutylaminopropylamine (1.5 parts by weight), α, ω-dihydroxydimethylpolysiloxane (40cs) (10 parts by weight) mixed, diluted with normal hexane (30 parts by weight), and dropped. Then, the mixture was heated and stirred at 200 ° C. for 1 hour, and the solvent was further removed and cooled to obtain a surface-modified titanium powder. This titanium powder had a triboelectric charge of +150 μC / g with the iron powder carrier, a hydrophobicity of 80% by a transmittance method, a BET specific surface area of 30 m ² / g, and a carbon content of 4.3% by weight. In addition, this titanium powder is
The triboelectric charge after leaving for 48 hours under the L condition is +200.
It was μC / g, the triboelectric charge after standing for 48 hours under HH conditions showed +130 μC / g, and the charging ratio (HH / LL) was 0.65. Further, 0.5% by weight of this titanium powder was added to a 7 μm positively chargeable toner, and printing was performed on 20,000 or more sheets using a commercially available copying machine. The image characteristics were good without fogging. Further, 5% by weight of this fine powder was added to an epoxy resin (trade name: Ehjicoat 828) and kneaded with three rolls, and the viscosity was measured with an E-type viscometer.
(2.5 rpm), 40 Pas (20 rpm), thixotropic index (TI)
Was 1.5. To this, triethylenetetramine was added as a curing agent, and the adhesive strength measured according to JIS K 6850 was 50 kgf / cm ² . All of these evaluation results showed a significant improvement compared to Comparative Example 4.

Comparative Example 4 In Example 4, the epoxy group-containing silane and α, ω
-Instead of dihydroxydimethylpolysiloxane (both terminal reactive group-blocked organopolysiloxane), an epoxy-modified organopolysiloxane (FZ3745, manufactured by Nippon Yunika)
A surface-modified titanium powder was obtained by performing the same treatment as in Example 4 except for using. This titanium powder had a triboelectric charge of +100 μC / g with an iron powder carrier, a hydrophobicity of 65% by a transmittance method, a BET specific surface area of 30 m ² / g, and a carbon content of 3.5% by weight. The triboelectric charge after leaving this titanium powder for 48 hours under LL conditions is +125 μC / g.
The triboelectric charge after standing for 48 hours under HH conditions showed +50 μC / g, and the charge ratio (HH / LL) was 0.40. This titanium powder was added to a 7 μm positively-chargeable toner in an amount of 0.
When 5% by weight was added and 1000 sheets were printed using a commercially available copying machine, fogging occurred in image characteristics. Further, 5% by weight of this fine powder was added to an epoxy resin (trade name: Ehjicoat 828) and kneaded with a three-roll mill, and the viscosity was measured with an E-type viscometer. The viscosity was 40 Pa · s (20 rpm) and the thixotropic index (TI) was 1.3. To this, triethylenetetramine was added as a curing agent, and the adhesive strength measured according to JIS K 6850 was 45 kgf / cm ² .

Example 5 100 parts by weight of ultrafine aluminum oxide (specific surface area: 100 m ² / g, manufactured by Degussa: aluminum oxide @C) were put into a mixer, and the mixture was stirred under a nitrogen atmosphere while stirring to obtain an epoxy group-containing silane (Shin-Etsu Chemical Co., Ltd.). (KBM403), 0.7 part by weight of dibutylaminopropylamine, 15 parts by weight of α, ω-dihydroxymethylphenylpolysiloxane (100 cs), and a mixture diluted with 40 parts by weight of normal hexane is dropped. And 2
The mixture was heated and stirred at 00 ° C. for 1 hour, and after further removing the solvent and cooling, a surface-modified alumina powder was obtained. This alumina powder has a triboelectric charge amount of −100 μC / g with an iron powder carrier,
85% hydrophobicity and 60% BET specific surface area by transmittance method
m ² / g, and the amount of carbon was 6.0% by weight. The triboelectric charge after leaving this alumina powder for 48 hours under LL conditions was -130 μC / g,
The amount of triboelectric charge after standing for a time shows -70 μC / g,
The charge ratio (HH / LL) was 0.54. Further, 0.5% by weight of this alumina powder was added to a 7 μm negatively chargeable toner, and printing was performed on 20,000 or more sheets using a commercial copying machine. The image characteristics were good without fogging. Also, 5% by weight of this fine powder was added to an epoxy resin (trade name: Ehjicoat 828) and kneaded with a three-roll mill, and the viscosity was measured with an E-type viscometer. 47 Pa · s (20 rpm) and thixotropic index (TI) were 1.5. To this, triethylenetetramine was added as a curing agent, and the adhesive strength measured according to JIS K 6850 was 55 kgf / cm ² .
All of these evaluation results showed a significant improvement compared to Comparative Example 5.

Comparative Example 5 In Example 5, instead of α, ω-dihydroxydimethylpolysiloxane (both terminal reactive group-blocked organopolysiloxane), methylphenylpolysiloxane blocked by trimethylsilyl at both terminals (KF50- manufactured by Shin-Etsu Co., Ltd.) A surface-modified alumina powder was obtained by performing the same treatment as in Example 5 except that 100) was used. This alumina powder has a triboelectric charge of −80 μC / g with an iron powder carrier, and a hydrophobicity of 2 according to a transmittance method.
0%, BET specific surface area 70 m ² / g, carbon amount 6.
It was 5% by weight. This alumina powder was dried under LL conditions for 4 hours.
The triboelectric charge after leaving for 8 hours is −100 μC / g, and the triboelectric charge after leaving for 48 hours under HH conditions is −
The charge ratio (HH / LL) was 0.30. This alumina powder is added to a 7 μm negatively chargeable toner by 0.5.
When 5,000 sheets were printed using a commercial copying machine, fog occurred in the image characteristics. Further, 5% by weight of this fine powder was added to an epoxy resin (trade name: Ehjicoat 828) and kneaded with a three-roll mill, and the viscosity was measured with an E-type viscometer to find that the viscosity was 60 Pa · s (2.5 rpm). 45 Pa · s (20 rpm) and thixotropic index (TI) were 1.3. To this, triethylenetetramine was added as a curing agent, and the adhesive strength measured according to JIS K 6850 was 48 kgf / cm ² .

Claims (7)

[Claims] 1. A hydrophobic metal oxide fine powder obtained by treating a metal oxide fine powder with an epoxy group-containing silane, an amino group-containing organic compound and an organopolysiloxane having a terminal-reactive group. 2. The hydrophobic metal oxide fine powder according to claim 1, which has a hydrophobicity of 70% or more as measured by a transmittance method. 3. The metal oxide fine powder has a specific surface area of 10 to 400.
hydrophobic metal oxide fine powder according to claim 1 or 2 is m ² / g. 4. The hydrophobic metal oxide fine powder according to claim 1, 2 or 3, wherein the metal oxide fine powder is silica, titania or alumina. 5. An organopolysiloxane having a terminal-reactive-group-blocking type, represented by the following general formula: (Wherein, R is an alkyl group comprising a methyl group or an ethyl group, and may be partially substituted with an alkyl group containing any one of a functional group containing a vinyl group, a phenyl group, and an amino group; Is a halogen atom, a hydroxyl group or an alkoxy group, and n is an integer of 15 to 500), and the hydrophobic metal oxide fine powder according to any one of claims 1 to 4. 6. The hydrophobic metal oxide fine particle according to claim 1, wherein the organopolysiloxane having both terminal reactive groups blocked is treated with 1 to 50% by weight of the metal oxide fine powder. Powder. 7. A method comprising mixing a metal oxide fine powder having a specific surface area of 10 to 400 m ² / g with an epoxy group-containing silane, an amino group-containing organic compound and an organopolysiloxane having a terminal-reactive group-blocked organopolysiloxane, followed by heat treatment. Process for producing finely divided hydrophobic metal oxide powder