JP2608734B2 - Manufacturing method of modified alumina powder - Google Patents

Description

The present invention relates to a method for producing a modified alumina powder.

(Prior Art and Problems) Conventionally, inorganic fillers such as alumina (aluminum oxide) and silica (silicon dioxide) have been used as reinforcing fillers for plastics, rubber, paints and the like. Since inorganic powders are hydrophilic, they have poor dispersibility in the above-mentioned lipophilic materials, and have a disadvantage of insufficient performance as a reinforcing filler.

In order to remedy this drawback, a method of imparting lipophilicity by treating these inorganic particles in advance with a silane treating agent known as, for example, alkoxysilane, chlorosilane, silane coupling agent, silazane or the like is also available. Are known.

However, the target of these silane treatment agents is mainly silica or granules containing silica as a main component, and inorganic powders containing no silica, or inorganic powders containing a small amount of silica are silane-based. Even if treated with a treating agent,
Although some treatment effect is recognized, dispersibility is not sufficient, and the performance as a reinforcing filler is not sufficient.
In particular, since alumina has a hydrophilic surface structure, it has poor dispersibility in plastics, rubber, paints, and the like, and even when treated with the above-mentioned silane treatment agent, the performance of these materials as a reinforcing filler is reduced. It is difficult to demonstrate.

(Means for Solving the Problems) The present inventors have improved the dispersibility of alumina or alumina-containing granules in lipophilic plastics, rubbers, paints, and the like, and used a reinforcing filler for these materials. As a result of repeated investigations for the purpose of increasing the performance as a result of the present invention, the gist of the present invention is to bond silica to alumina or powder containing alumina and then treat with a silane treatment agent The present invention resides in a method for producing a modified alumina powder.

 Hereinafter, the present invention will be described in detail.

Examples of the alumina or the alumina-containing powder in the present invention include alumina alone or a compositionally alumina-containing compound or a mixture thereof. For example, a granular material comprising one or a mixture of two or more of clay, talc, kaolin, bentonite, diatomaceous earth, mica (including sericite) and the like is used. As for the size of the powder, for example, the average particle diameter is several tens of microns (mμ).
Any of ultrafine particles to coarse particles of several hundred microns (μ) can be used.

In the present invention, silica is first bonded to the above alumina or a powder containing alumina (hereinafter, these are referred to as alumina powder). That is, the surface of the alumina powder is firmly covered entirely or partially with silica.

As a method of bonding silica to alumina powder,
For example, (1) A water or alcohol dispersion (silica sol) of silica is added to an alumina powder or a water suspension or a wet cake containing the powder, and the temperature is from room temperature to about 100 ° C. or less. After uniformly mixing, if necessary, filtering and drying.

(2) An aqueous solution of an alkali silicate (sodium salt, potassium salt, lithium salt, ammonium salt, etc.) or an alcohol solution of a silicate ester is added to the alumina powder or a water suspension or a wet cake containing the powder. And room temperature
A method of uniformly mixing at a temperature of about 100 ° C. or less, followed by filtration and drying if necessary. (3) While stirring the alumina powder with a suitable stirrer,
A method of spraying a dispersion or solution containing the above silica or alkali silicate at a temperature of room temperature to about 100 ° C. or lower to thereby uniformly mix the mixture and then drying the mixture is employed.

The amount of silica used is preferably in the range of 0.1 to 30 parts by weight in terms of SiO ₂ with respect to 100 parts by weight of alumina or a granular material containing alumina, and the effect of modifying alumina particles is less than 0.1 part by weight. If it is not sufficient, and if it exceeds 30 parts by weight, the cost is high and the amount of secondary particles generated increases, which adversely affects the reforming effect.

In the method of the present invention, after the silica is bonded to the alumina powder by the above-mentioned method, it is further treated with a silane treating agent.

As the silane treatment agent used in the present invention, for example,
The following silane compounds described in the catalog TSB-10 “silane compound” of Toshiba Silicone Co., Ltd. are exemplified.

(1) alkoxysilane compound: for example, tetramethoxysilane, methyltrimethoxysilane, dimethyldiethoxysilane, tetramethoxysilane, etc. (2) chlorosilane compound: for example, methyltrichlorosilane, dimethyldichlorosilane, etc. (3) silane coupling agent: for example Vinyltriethoxysilane, γ-aminopropyltriethoxysilane, N
-(Β-aminoethyl) -γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, etc. (4) Silazane compound: for example, hexamethyldisilazane, dimethyltrimethylsilylamine, etc. Treatment with these silane treating agents Is sprayed with a diluent of a silane treatment agent at a temperature of room temperature to about 120 ° C. or less while stirring the alumina powder to which the silica is bonded by the above-described method with a suitable stirrer. Then, a method of drying, or dispersing alumina powder particles bonded with silica in water to form a slurry, adding a diluent of the silane treatment agent thereto under stirring, and uniformly mixing at the above temperature Thereafter, a method of drying and the like are employed.

(Effect of the Invention) In the modified alumina powder obtained by the method of the present invention, all or at least a part of the surface of the alumina powder is firmly covered with a silane treatment agent via a silica layer, and the lipophilic property is improved. Since a layer is formed, when it is used as a reinforcing filler for lipophilic plastics, rubber, paints, etc., it has good dispersibility in these materials and exhibits an excellent reinforcing effect. Can be.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist.

Example 1 100 parts by weight of alumina having an average particle size of 2 mμ was stirred at a high speed (1500 rpm) in a Henschel mixer while the solid content was 30%.
% Silica sol (Snowtex 30, Nissan Chemical Co., Ltd.) 10
Parts by weight were added, mixed for about 5 minutes, and dried at 110 ° C. Next, a solution obtained by diluting 1 part by weight of γ-aminopropyltriethoxysilane (KBE903, manufactured by Shin-Etsu Chemical Co., Ltd.) with 10 parts by weight of methanol was sprayed on the same while stirring it in a Henschel mixer as described above, Then, drying was performed to obtain a modified alumina powder.

Example 2 In place of the methanol solution of γ-aminopropyltriethoxysilane used in Example 1, 1 part by weight of γ-glycidoxypropyltrimethoxysilane (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) was added with 10 parts by weight of methanol. Except for using the diluted solution, the same treatment as in Example 1 was performed to obtain modified alumina powder.

Comparative Example 1 While 100 parts by weight of alumina having an average particle size of 2 mμ was stirred at high speed in a Henschel mixer, 1 part by weight of γ-
A solution obtained by diluting aminopropyltriethoxysilane with 10 parts by weight of methanol was sprayed and then dried to obtain alumina powder.

Comparative Example 2 In place of the methanol solution of γ-aminopropyltriethoxysilane used in Comparative Example 1, 1 part by weight of γ-glycidoxypropyltrimethoxysilane was added to methanol.
Except that the solution diluted with 10 parts by weight was used, the same treatment as in Comparative Example 1 was performed to obtain alumina powder.

Example 3 Sericite having an average particle size of 2 mμ (manufactured by Sanshin Mining Co., Ltd.)
While stirring at a high speed in a Henschel mixer, 10 parts by weight of silica sol having a solid content of 30% was added as in Example 1, mixed for about 5 minutes, and dried at 110 ° C. Then, while stirring this in a Henschel mixer, 1 part by weight of γ-aminopropyltriethoxysilane was added to methanol 10
The solution diluted in parts by weight was sprayed and then dried to obtain a modified alumina powder.

Example 4 In place of the methanol solution of γ-aminopropyltriethoxysilane used in Example 3, 1 part by weight of γ-glycidoxypropyltrimethoxysilane (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) was added with 10 parts by weight of methanol. Except for using the diluted solution, the same treatment as in Example 3 was performed to obtain modified alumina powder.

Comparative Example 3 While 100 parts by weight of sericite having an average particle diameter of 2 mμ was stirred at high speed in a Henschel mixer, 1 part by weight of γ was added thereto.
A solution obtained by diluting -aminopropyltriethoxysilane with 10 parts by weight of methanol was sprayed and then dried to obtain alumina powder.

Comparative Example 4 In place of the methanol solution of γ-aminopropyltriethoxysilane used in Comparative Example 3, 1 part by weight of γ-glycidoxypropyltrimethoxysilane was replaced with methanol.
Except for using the solution diluted with 10 parts by weight, the same treatment as in Comparative Example 3 was performed to obtain an alumina powder.

Test Example 1 The lipophilicity of the alumina powder samples obtained in Examples 1 and 2 and Comparative Examples 1 and 2 was measured by the following methods (a) and (b). Table 1 shows the results.

Similarly, the lipophilicity of the alumina powder samples obtained in Examples 3 and 4 and Comparative Examples 3 and 4 was measured by the methods (A) and (B). Table 2 shows the results.

(A) Affinity for hydrophobic solvent: 5 g of each sample was added to a 100 ml beaker containing 50 g of toluene and n-hexane, and the mixture was sufficiently stirred at 20 ° C, and then 10 g of water was added and stirred vigorously again. After that, the sample was allowed to stand and the degree of movement of the sample to the oil layer and the aqueous layer was observed.
Discrimination is made in the order of → 相 対 → ▲ → × (relative value).

(B) Fluctuation in viscosity of liquid paraffin dispersion: Each sample was mixed with 10 times (weight) of liquid paraffin, and the viscosity of the resulting dispersion was measured with a B-type viscometer (No. 1, 60 rpm). , 60 seconds).

The viscosity of the liquid paraffin dispersion indicates the degree of decrease in viscosity, where the viscosity of untreated alumina is 10.

The viscosity of the liquid paraffin dispersion indicates the degree of decrease in viscosity, where the viscosity of untreated sericite is 10.

Test Example 2 Untreated alumina powder, Examples 1-2 and Comparative Example 1
40 parts by weight and 100 parts by weight of the polypropylene resin obtained in the above steps 2 to 2 were pelletized by using an extruder, and then compression-molded at 175 ° C. Table 3 shows the results of measuring the tensile strength and bending strength of the molded product.

Similarly, untreated sericite granules, 40 parts by weight of the alumina granules obtained in Examples 3 to 4 and Comparative Examples 3 to 4
Each of 0 parts by weight of the polypropylene resin was pelletized using an extruder, and then compression-molded at 175 ° C. Table 4 shows the results of measuring the tensile strength and bending strength of the molded product.

The tensile strength of the molded product in Tables 3 and 4 is as follows:
The tensile strength of untreated alumina and sericite is shown as a relative value with 100, and the bending strength of the molded product is
The relative values are shown with the bending strength of untreated alumina and sericite being 200.

Claims (1)

(57) [Claims] 1. A method for producing a modified alumina powder, comprising bonding silica to alumina or a powder containing alumina, followed by treating with a silane treating agent.