JPH0687609A - Silicon dioxide fine powder for resin filler - Google Patents

Abstract

PURPOSE:To prevent a silicon dioxide fine powder from becoming cloudy at the time of mixing with a resin and to obtain a low torque value by giving hydrophobic treatment to silicon dioxide fine powder obtained by flame hydrolysis of halogenated silane by an organic silicon compound before mechanically crushing. CONSTITUTION:Gaseous silicon tetrachloride is passed through the flame of oxygen and hydrogen and given hydrolysis under high temperatures to obtain fine powder is silicon dioxide. An organic silicon compound for hydrophobic treatment is that which is combined with hydroxide groups of the surface of the silicon dioxide fine powder to block them and in itself has hydrophobic groups. For example, it is hexamethyldisilazane. Its used quantity is 0.5-40wt.% of the raw material, silicon dioxide fine powder. Reaction conditions of the hydrophobic treatment are not specially limited, but both the compounds are mixed in an atmosphere of inert gas and kept at 60-350 deg.C for 10min to 4hr before the mixture is dried to remove unreacted substances and by-products. After hydrophobic treatment, the product is pulverized by a ball mill, etc., to obtain powder of 80-180m<2>/g specific surface area, 80-300g/l bulk density and <=10kg.cm torque reference after resin filling.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a hydrophobized silicon dioxide fine powder which, when added to various resin compositions, does not impair the transparency of the resin and can maintain a low torque value before curing. Regarding

In various resin compositions used as room temperature curable elastomers, adhesives, high temperature vulcanizing silicone rubbers, etc., fillers are often added to the resin in order to impart high strength properties after curing, and it is conventional. , Silicon dioxide powder is used as a filler. On the other hand, these resin compositions are required to have a torque value before curing as low as possible, specifically 10 kg / cm or less, from the viewpoints of molding time, handling ease during molding, and the like. However, in general, the larger the amount of filler added, the higher the torque value of the resin.
Under the condition that about 0 parts by weight is added to achieve the required strength,
It is difficult to obtain a torque value of 10 kg / cm or less.

[0003] Therefore, conventionally, a specific surface area of the silicon dioxide powder 80m ² / g~180m ² / g, bulk density 80 g / l to 300 g /
Attempts have been made to obtain a low torque value by making it finer to l and making it hydrophobic, but since the above-mentioned conventional silicon dioxide powder contains many agglomerates, filling this with a resin will make the resin transparent. There is a damaging problem. As an example, the torque value when adding 40 parts by weight of the conventional fine powder of silicon dioxide powder to 100 parts by weight of silicone oil is 8 kg · cm, but the resin is clouded and transparent because it contains a lot of aggregates. Is damaged. The agglomerates are white coarse particles having a particle size of about 1 mm, which are generated by agglomeration of silicon dioxide fine particles,
It does not disperse even if it is added to the resin and mechanically mixed by stirring.

[0004]

DISCLOSURE OF THE INVENTION The present invention is to solve the above-mentioned problems of the prior art, and when added to a resin, does not impair the transparency of the resin, and further imparts a low torque value to the hydrophobized silicon dioxide. An object is to provide a method for producing fine powder.

Conventionally, the specific surface area is 80 m ² / g to 180 m ² /
g, hydrophobized silicon dioxide fine powder having a bulk specific gravity of 80 g / l to 300 g / l is obtained by mechanically grinding silicon dioxide obtained by flame hydrolysis of halogenated silane together with a hydrophobizing agent of an organosilicon compound, or It is manufactured by mechanically grinding the silicon dioxide and then hydrophobizing it. We have
Aggregates contained in conventional silicon dioxide powder are generated when the powder is mechanically pulverized into fine particles, and are caused by excessive mechanical pulverization force applied to the powder having poor fluidity. The present inventors have found that it is possible to obtain fine particles of silicon dioxide with less agglomerates by pulverizing the silicon dioxide powder after hydrophobizing it.

[0006]

According to the present invention, a silicon dioxide fine powder obtained by flame hydrolysis of a halogenated silane is hydrophobized with an organic silicon compound and then mechanically pulverized. A method for producing silicon dioxide fine powder is provided.

The silicon dioxide powder produced by flame hydrolysis of the halogenated silane used in the present invention means, for example, the silicon dioxide powder produced by the method disclosed in Japanese Patent Publication No. 47-46274. This production method is a method in which silicon tetrachloride gas is passed through a flame of oxygen and hydrogen to cause hydrolysis at high temperature, and fine particles of silicon dioxide are obtained.

The hydrophobizing treatment of silicon dioxide can be carried out by a conventional hydrophobizing method of this kind, and the organosilicon compound to be used may be one generally used as a hydrophobizing agent. A commonly used hydrophobizing agent is a compound that binds in some form and blocks the hydroxyl group on the surface of silicon dioxide powder, and has a hydrophobic group by itself. A silane coupling agent, a silylating agent, or the like, and specifically, for example, an organosiloxane such as hexamethyldisilazane, hexamethyldisiloxane, trimethylsilanol, trimethylsilaneethoxide, trimethylsilanemethoxide, or an organopolysiloxane. Are preferably used.

The amount of the above-mentioned organosilicon compound used as a hydrophobizing agent is not particularly limited, but in practice, it is preferably 0.5 to 40% by weight based on the raw material silicon dioxide fine powder. When the amount used is less than 0.5% by weight, the effect of hydrophobizing is low, and even when the amount used exceeds 40% by weight, there is no great difference in the effect of hydrophobicizing. Further, the reaction conditions for the hydrophobizing treatment are not particularly limited, but preferably 6 under an inert gas atmosphere.
A method may be used in which the organosilicon compound is mixed with the silicon dioxide powder in a temperature range of 0 ° C. to 350 ° C., and the mixture is held for 10 minutes to 4 hours and then dried to remove unreacted substances and by-products. Oxidation of the hydrophobizing agent is prevented by carrying out the hydrophobizing reaction in an inert gas atmosphere. Reaction temperature is 60 ℃
If it is lower than this, the hydrophobic reaction does not proceed sufficiently,
If the temperature is higher than ° C, the hydrophobizing agent is thermally decomposed, which is not preferable.

[0010] The silicon dioxide powder of the raw material after the hydrophobic treatment, a specific surface area of 80m ² / g~180m ² / g, bulk density 80 g /
Grind mechanically until l-300 g / l. As the mechanical crushing means, a usual crusher such as a ball mill, a conical mill or a tower mill can be used. Further, it may be crushed by utilizing the grinding force like a stone mill. Grinding conditions are also not particularly limited. As an example, when pulverizing with a normal ball mill, the number of revolutions should be 5 to 5 at a rotation speed of 10 to 200 rpm.
It suffices to stir for minutes to 8 hours. When the specific surface area and bulk specific gravity are out of the above ranges, when the silicon dioxide powder is added to the resin, the torque value before curing the resin is 10 kg.
More than cm.

By finely grinding the raw material silicon dioxide powder after hydrophobizing it, fine powder of silicon dioxide containing few agglomerates can be obtained. When the mechanical pulverization treatment is carried out simultaneously with the hydrophobizing treatment, the degree of cloudiness of the resin when added to the resin is less than that of the method of performing the hydrophobizing treatment after the mechanical pulverization, but in that the transparency is maintained. Still not enough. This is because the silicon dioxide powder is mechanically pulverized at a stage where the hydrophobization treatment is not sufficiently performed, so that the agglomerates are still generated, and the agglomerates are contained in an amount that affects the transparency. it is conceivable that.

[0012]

The silicon dioxide fine powder obtained by the production method of the present invention does not cause clouding when mixed with resin, and a low torque value can be obtained. As an example, by mixing 40 parts by weight of the silicon dioxide fine powder with 100 parts by weight of silicone oil, a transparent resin composition having a torque value of 8 kg · cm can be obtained.

[0013]

EXAMPLES AND COMPARATIVE EXAMPLES The present invention will be specifically described below based on examples, but the following examples do not limit the present invention.

Example 1 Silicon dioxide powder obtained by hydrolyzing silicon tetrachloride in an oxyhydrogen flame (manufactured by Nippon Aerosil Co., Ltd .: trade name Aerosil 200) 200
After 13 g of hexamethyldisilazane was added to and mixed with g, heat treatment was carried out at 150 ° C. to obtain 211 g of hydrophobized silicon dioxide powder. This silicon dioxide powder has an internal volume of 4
It was charged into a 00 liter ball mill and pulverized for 2 hours to obtain a fine powder having a specific surface area of 160 m ² / g and a bulk specific gravity of 240 g / l. 40 parts of this silicon dioxide powder and 100 parts of transparent silicone oil (trade name KF96: 10000CS) were put in a rotor mixer and mixed (60 rpm, 30 ° C, 15 minutes), and a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) was used. The torque value of the silicone oil was measured. The torque value was 8 kg · cm. The silicone oil mixed with the silicon dioxide powder was transparent without clouding.

Example 2 Instead of the dioxide powder of Example 1, another hydrophobized silicon dioxide powder (manufactured by Nippon Aerosil Co., Ltd .: trade name RY200)
Was pulverized in the same manner as in Example 1 to obtain a specific surface area of 105
A silicon dioxide powder having a m ² / g and a bulk specific gravity of 148 g / l was obtained. This powder was added to silicone oil under the same conditions as in Example 1 and the torque value was measured and found to be 5 kg · cm.
The silicone oil mixed with the silicon dioxide powder was transparent without clouding.

Example 3 Silicon dioxide powder obtained by hydrolyzing silicon tetrachloride in an oxyhydrogen flame (manufactured by Nippon Aerosil Co., Ltd .: trade name Aerosil 200) 200
After adding and mixing 4 kg of trimethylethoxysilane to g, heat treatment was performed at 150 ° C. to obtain a hydrophobized silicon dioxide powder. This silicon dioxide powder was charged into a ball mill having an internal volume of 400 liters and pulverized for 2 hours to give a specific surface area of 15
A fine powder having a volume specific gravity of 1 m ² / g and a bulk specific gravity of 86 g / l was obtained. The silicon dioxide powder was added to silicone oil under the same conditions as in Example 1 and the torque value was measured and found to be 9 kg · cm. The silicone oil mixed with the silicon dioxide powder was transparent without clouding.

Comparative Example 1 In the treatment step of Example 3, except that the raw material silicon dioxide powder was pulverized to a bulk specific gravity of 135 g / l prior to the hydrophobic treatment, and then the hydrophobic treatment was carried out at a temperature of 180 ° C. Was treated in the same manner as in Example 3 to obtain a silicon dioxide powder having a specific surface area of 140 m ² / g and a bulk specific gravity of 150 g / l. When this powder was added to silicone oil under the same conditions as in Example 1 and the torque value was measured, the torque value was 9 kg · cm.
The silicone oil was cloudy.

Comparative Example 2 20 kg of silicon dioxide powder obtained by hydrolyzing silicon tetrachloride in an oxyhydrogen flame (product name Aerosil200, manufactured by Nippon Aerosil Co., Ltd.)
And 4 kg of trimethylethoxysilane were placed in a ball mill with an internal volume of 400 liters, kept at 70 ° C, and then 2 at 60 rpm.
After rotating for an hour, the contents were heated to 200 ° C in a nitrogen stream,
It was kept for 2 hours to volatilize and remove unreacted materials and by-products.
The specific surface area of the obtained hydrophobized silicon dioxide powder is 15
The specific gravity was 8 m ² / g and the bulk specific gravity was 214 g / l. When this powder was added to silicone oil under the same conditions as in Example 1 and the torque value was measured, the torque value was 8 kg · cm.
The silicone oil was cloudy.

[Procedure amendment]

[Submission date] August 26, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

[Title of Invention] Silicon dioxide fine powder for resin filler

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-filled silicon dioxide fine powder which, when added to various resin compositions, can maintain a low torque value before curing without impairing the transparency of the resin.

In various resin compositions used as room temperature curable elastomers, adhesives, high temperature vulcanizing silicone rubbers, etc., fillers are often added to the resin in order to impart high strength characteristics after curing, , Silicon dioxide powder is used as a filler. On the other hand, these resin compositions are required to have a torque value before curing as low as possible, specifically, 10 Kg · cm or less, from the viewpoints of molding time and handling during molding. However, generally, when the amount of the filler added is increased, the torque value of the resin is increased, and when the usual silicon dioxide powder is used, it is added under the condition that about 40 parts by weight of this is added to achieve the required strength. -It is difficult to obtain a torque value of cm or less.

[0003] Therefore, conventionally, a specific surface area of the silicon dioxide powder ^{80m 2} / ^g~180m 2 / g, bulk density 80~300g
Attempts have been made to obtain a low torque value by hydrophobizing to 1 / l and consolidating. However, since the above-mentioned conventional silicon dioxide powder contains a lot of agglomerates, filling this with a resin will make the resin transparent. There is a damaging problem. As an example, the torque value when adding 40 parts by weight of the conventional fine powder of silicon dioxide powder to 100 parts by weight of silicone oil is 8 kg · cm, but the resin is clouded and transparent because it contains a lot of aggregates. Is damaged. The agglomerates are white coarse particles having a particle diameter of about 1 mm generated by agglomeration of fine particles of silicon dioxide, and do not disperse even if they are added to a resin and mechanically stirred and mixed.

[0004]

DISCLOSURE OF THE INVENTION The present invention is to solve the above-mentioned problems of the prior art, and when added to a resin, it does not impair the transparency of the resin, and yet it has a low torque value and is filled with a hydrophobic resin. The object is to provide a silicon dioxide fine powder for use.

Conventionally, a hydrophobized silicon dioxide fine powder having a specific surface area of 80 to 180 m ² / g and a bulk specific gravity of 80 to 300 g / l is obtained by subjecting silicon dioxide obtained by flame hydrolysis of a halogenated silane to a hydrophobized organosilicon compound. It is manufactured by mechanically grinding with an agent or by mechanically grinding the silicon dioxide and then hydrophobizing it. The present inventors have found that the agglomerates contained in the conventional silicon dioxide powder are generated when the powder is mechanically pulverized into fine particles, and excessive mechanical pulverization force is applied to the powder having poor fluidity. It was found that this was caused by the fact that the silicon dioxide powder was subjected to a hydrophobizing treatment and then pulverized to obtain fine particles of silicon dioxide with few agglomerates. This impairs the transparency of the resin when it is filled in the resin. No
Moreover, we have obtained the knowledge that a low torque value can be given. The present invention has solved the above-mentioned conventional problems based on such findings.

[0006]

According to the present invention, the following silicon dioxide fine powder for resin filling is provided. (1) A silicon dioxide fine powder for a resin filler, which has a reference torque value of 10 Kg · cm or less after filling the resin,
Silicon dioxide fine powder that maintains the transparency of the resin. (2) Specific surface area 80 to 180 m ² / g, bulk specific gravity 80 to
The silicon dioxide fine powder of (1) above, which has a reference torque value of 10 kg / cm or less after filling the resin with 300 g / l and maintains the transparency of the resin.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The silicon dioxide powder used in the present invention is obtained by flame hydrolysis of a halogenated silane, and is produced, for example, by the method disclosed in JP-B-47-46274. This production method is a method in which silicon tetrachloride gas is passed through a flame of oxygen and hydrogen to cause hydrolysis at high temperature, and fine particles of silicon dioxide are obtained.

The silicon dioxide powder of the present invention is hydrophobized with an organic silicon compound. The method of hydrophobizing treatment can be carried out by a conventionally used method, and the organosilicon compound used may be one generally used as a hydrophobizing agent. A commonly used hydrophobizing agent is a compound that binds in some form and blocks the hydroxyl group on the surface of silicon dioxide powder, and has a hydrophobic group by itself. A silane coupling agent, a silylating agent, or the like, and specifically, for example, an organosiloxane such as hexamethyldisilazane, hexamethyldisiloxane, trimethylsilanol, trimethylsilaneethoxide, trimethylsilanemethoxide, or an organopolysiloxane. Are preferably used.

The amount of the above-mentioned organosilicon compound used as a hydrophobizing agent is not particularly limited, but in practice, it is preferably 0.5 to 40% by weight based on the raw material silicon dioxide fine powder. When the amount used is less than 0.5% by weight, the effect of hydrophobizing is low, and even when the amount used exceeds 40% by weight, there is no great difference in the effect of hydrophobicizing. Further, the reaction conditions for the hydrophobizing treatment are not particularly limited, but preferably 6 under an inert gas atmosphere.
A method may be used in which the organosilicon compound is mixed with the silicon dioxide powder in a temperature range of 0 ° C. to 350 ° C., and the mixture is held for 10 minutes to 4 hours and then dried to remove unreacted substances and by-products. Oxidation of the hydrophobizing agent is prevented by carrying out the hydrophobizing reaction in an inert gas atmosphere. Reaction humidity is 60 ° C
If it is lower than this, the hydrophobic reaction does not proceed sufficiently,
If the temperature is higher than ° C, the hydrophobizing agent is thermally decomposed, which is not preferable.

After hydrophobizing the raw material silicon dioxide powder, it has a specific surface area of 80 to 180 m ² / g and a bulk specific gravity of 80 to 30.
Grind mechanically to 0 g / l. As the mechanical crushing means, a usual crusher such as a ball mill, a conical mill or a tower mill can be used. Further, it may be crushed by utilizing the grinding force like a stone mill. Grinding conditions are also not particularly limited. As an example, in the case of crushing using a normal ball mill, the number of rotations is 10 to 200 rpm and 5 minutes to
Stir for 8 hours. When the specific surface area and the bulk specific gravity are out of the above ranges, when the silicon dioxide powder is added to the resin, the torque value before curing the resin is 10 Kg · c.
m or more.

By finely grinding silicon dioxide powder as a raw material and then mechanically pulverizing it, a fine powder of silicon dioxide containing few agglomerates can be obtained. When the mechanical pulverization treatment is carried out simultaneously with the hydrophobizing treatment, the degree of cloudiness of the resin when added to the resin is less than that of the method of performing the hydrophobizing treatment after the mechanical pulverization, but in that the transparency is maintained. Still not enough. This is because the silicon dioxide powder is mechanically pulverized at a stage where the hydrophobization treatment is not sufficiently performed, so that the agglomerates are still generated, and the agglomerates are contained in an amount that affects the transparency. it is conceivable that.

[0012]

Industrial Applicability The silicon dioxide fine powder of the present invention obtained as described above does not cause clouding when mixed with a resin, and a low torque value can be obtained. As an example, by mixing 40 parts by weight of the silicon dioxide fine powder with 100 parts by weight of silicone oil, a transparent resin composition having a torque value of 8 kg · cm can be obtained. In this specification, for convenience of description, a torque value when 40 parts by weight of silicon dioxide fine powder is mixed with 100 parts by weight of silicone oil is used as a reference torque value.

[0013]

EXAMPLES AND COMPARATIVE EXAMPLES The present invention will be specifically described below based on examples, but the following examples do not limit the present invention.

Example 1 Silicon dioxide powder obtained by hydrolyzing silicon tetrachloride in an oxyhydrogen flame (product name Aerosil 20 manufactured by Nippon Aerosil Co., Ltd.)
0) 13 g of hexamethyldisilazane was added to 200 g and mixed, and then heat treated at 150 ° C. to obtain 211 g of hydrophobized silicon dioxide powder. This silicon dioxide powder was charged into a ball mill having an internal volume of 4 liters and pulverized for 2 hours to obtain a fine powder having a specific surface area of 160 m ² / g and a bulk specific gravity of 240 g / l. 40 parts of this silicon dioxide powder and 100 of transparent silicone oil (trade name KF96: 10000CS)
Part into a rotor mixer and mix (60 rpm, 30
℃, 15 minutes), Labo Plastomill (Toyo Seiki Co., Ltd.)
When the standard torque value of the silicone oil was measured using, it was 8 Kg · cm. The silicone oil mixed with the silicon dioxide powder was transparent without clouding.

Example 2 Instead of the dioxide powder of Example 1, another hydrophobized silicon dioxide powder (manufactured by Nippon Aerosil Co., Ltd .: trade name RY20) is used.
0) and pulverized in the same manner as in Example 1 to give a specific surface area of 1
05m ² / g, to obtain a silicon dioxide powder of bulk density 148 g / l. This powder was added to silicone oil under the same conditions as in Example 1 to measure the reference torque value.
・ It was cm. The silicone oil mixed with the silicon dioxide powder was transparent without clouding.

Example 3 Silicon dioxide powder obtained by hydrolyzing silicon tetrachloride in an oxyhydrogen flame (product name Aerosil 20 manufactured by Nippon Aerosil Co., Ltd.)
0) 40 g of trimethylethoxysilane was added to 200 g and mixed, and then heat treated at 150 ° C. to obtain a hydrophobized silicon dioxide powder. This silicon dioxide powder was charged into a ball mill having an internal volume of 4 liters and pulverized for 2 hours to obtain a fine powder having a specific surface area of 151 m ² / g and a bulk specific gravity of 86 g / l. When this silicon dioxide powder was added to silicone oil under the same conditions as in Example 1 and the reference torque value was measured, it was 9 Kg · cm. The silicone oil mixed with the silicon dioxide powder was transparent without clouding.

Comparative Example 1 In the treatment step of Example 3, the raw material silicon dioxide powder was pulverized to a bulk specific gravity of 135 g / l prior to the hydrophobic treatment, and then the hydrophobic treatment was carried out at a temperature of 180 ° C. Was treated in the same manner as in Example 3 to give a specific surface area of 140 m ² / g,
A silicon dioxide powder having a bulk specific gravity of 150 g / l was obtained. When this powder was added to silicone oil under the same conditions as in Example 1 and the reference torque value was measured, it was 9 Kg · cm, but the silicone oil was cloudy.

Comparative Example 2 Silicon dioxide powder obtained by hydrolyzing silicon tetrachloride in an oxyhydrogen flame (product name Aerosil 20 manufactured by Nippon Aerosil Co., Ltd.)
0) 20 kg and 4 kg of trimethylethoxysilane were placed in a ball mill having an internal volume of 400 liters, kept at 70 ° C. and rotated at 60 rpm for 2 hours, and then the contents were kept at 200 ° C. for 2 hours in a nitrogen stream to react unreacted. The substances and by-products were removed by volatilization. The hydrophobized silicon dioxide powder obtained had a specific surface area of 158 m ² / g and a bulk specific gravity of 214 g / l. This powder was added to silicone oil under the same conditions as in Example 1 to measure the reference torque value.
It was g · cm, but the silicone oil was cloudy.

Claims (2)

[Claims] 1. A method for producing fine silicon dioxide powder, which comprises subjecting fine silicon dioxide powder obtained by flame hydrolysis of halogenated silane to hydrophobic treatment with an organosilicon compound and then mechanically pulverizing the fine powder. Wherein the silicon dioxide fine powder obtained by flame hydrolysis of halogenated silane after hydrophobic treatment with an organic silicon compound, a specific surface area of 80m ² / g~180m ² / g,
The method according to claim 1, wherein the bulk specific gravity is mechanically crushed to 80 g / l to 300 g / l.