JP2725857B2 - Method for producing hydrophobic organocolloidal silica - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a hydrophobic organocolloidal silica which is stably dispersed in a hydrophobic organic solvent. More specifically, the present invention is easy to operate during manufacturing,
In addition, the present invention relates to a method for inexpensively producing a stable hydrophobic organocolloidal silica having good compatibility and dispersibility with a hydrophobic organic solvent.

[Conventional technology and problems]

Conventionally, colloidal silica has been mixed with various industrial products using water or hydrophilic organic solvents such as methanol, ethanol, isopropanol, ethyl cellosolve, and butyl cellosolve as additives for improving the film formability of organic paints. , Has been used. In recent years, with the subdivision and high functionality of various industrial products, colloidal silica that can be used in hydrophobic organic solvents has been required,
As a method for producing such a hydrophobic colloidal silica, an attempt has been made to use a silane coupling agent.

For example, U.S. Pat. No. 4,027,073 describes a method of adding trialkoxysilane to aqueous colloidal silica.

U.S. Pat. No. 4,188,451 describes a method in which trialkoxysilane is added to a mixed system of hydrophilic organic solvent type colloidal silica and a small amount of water.

However, conventional methods using these silane coupling agents have poor gelation stability because self-condensation of the silane coupling agent occurs. In addition, it is necessary to use a large amount of an expensive silane coupling agent, and further, it requires careful attention to the operation, which is complicated and lacks the suitability for industrialization.

Therefore, an object of the present invention is that the operation at the time of production is simple, and the compatibility with the hydrophobic organic solvent, the dispersibility is good,
An object of the present invention is to provide a method for inexpensively producing a stable hydrophobic organocolloidal silica.

[Means for solving the problem]

That is, the present invention provides a method for producing a hydrophobic organocolloidal silica, comprising mixing a hydrophobic organic solvent and a cationic surfactant, adding an aqueous anionic colloidal silica thereto, and dehydrating the mixture. Things.

(Hydrophobic organic solvent) The hydrophobic organic solvent used in the present invention may be appropriately selected depending on the use of the hydrophobic organocolloidal silica.
Any desired hydrophobic organic solvent can be used, and is not particularly limited. Generally, a hydrophobic organic solvent having a solubility in water at 20 ° C. of 10 or less, preferably 3 or less [maximum amount of hydrophobic organic solvent (g) in 100 g of an aqueous solution (g)] is sufficiently applied to a hydrophobic product. can do. For example, toluene, benzene, xylene, methyl ethyl ketone, tetrahydrofuran and the like can be mentioned.

(Cationic Surfactant) The cationic surfactant that can be used in the present invention is not particularly limited, and for example, a “new surfactant”
(Horiguchi Hiroshi: Sankyo Publishing October 10, 1975) No. 493-5
Cationic surfactants described on page 74 and "List of Surfactants, etc., 1989 Edition" (Japan Surfactant Manufacturers Association) can be used.

Specifically, primary amine (salt) type, secondary amine (salt) type, tertiary amine (salt) type, quaternary ammonium (salt) type, amide type, imidazoline (derivative) type, polyamine (Salt) type, cationic starch type, polyalkylammonium (salt) type, polyoxyethylene type, cationic resin type, melamine resin type, dicyandiamide type, polyalkylenepolyamine (salt) type, special silicon type, diamide polyamine (salt) ) Type, amino-modified silicon type, lanolin derivative type, polyacrylic polymer type, fluororesin type, methylhydrogenpolysiloxane type, chiron type, polyurethane type, silicon zirconium type, special synthetic oil type,
Examples thereof include an aluminum derivative type, a chromium complex type, and a cocoamine acetic acid (salt) type. Preferably, primary amine and / or salt thereof, secondary amine and / or salt thereof, tertiary amine and / or salt thereof, imidazole and / or salt thereof, alkyl quaternary ammonium and / or salt thereof And quaternary ammoniums such as alkyl quaternary ammoniums having an element other than carbon and / or salts thereof, alkylbenzyl quaternary ammoniums and / or salts thereof, quaternary ammoniums having a nitrogen ring and / or salts thereof, and the like. And / or its salts, for example, (Wherein R ^{1 to} R ³ and R ^{8 to} R ¹⁸ are a linear, branched or cyclic alkyl group or alkenyl group having 1 to 30 carbon atoms, of which at least one in one molecule is carbon R ^{4 to} R ⁷ are linear or branched or cyclic alkyl or alkenyl groups having 1 to 25 carbon atoms, each having 5 to 30 atoms, preferably 8 to 25 atoms, which may be the same or different. Among them, at least one in one molecule has 5 to 25 carbon atoms, preferably 8 to 20 and may be the same or different, and R ¹⁹ has 7 to 25 carbon atoms, preferably A linear, branched or cyclic alkyl or alkenyl group of 9 to 20. A is a halogen, sulfate or nitrate, n is a number equal to the valence of A. X is -O-,
—S—, —NH—, an amide group or an ester group. ) And the corresponding surfactants such as amine, ammonium, imidazole and the like. The hydrophobic groups R ^{1 to} R ¹⁸ in the above formula may be any as long as the cationic surfactant can be easily dispersed or dissolved in a hydrophobic organic solvent at room temperature to a heated state. However, the present invention is not limited to this.

(Water-based anionic colloidal silica) The water-based anionic colloidal silica used in the present invention is not particularly limited as long as it is stable.
Any material can be used as long as it does not gel for at least one month under an atmosphere of ° C.

Examples of such aqueous colloidal silica include those synthesized by a deflocculation method and having an irregular particle shape as described in, for example, U.S. Pat.
Some of them are synthesized by an ion exchange method and have a spherical particle shape as described in No. 15022. The aqueous colloidal silica used in the present invention may be synthesized by either the peptization method or the ion exchange method, but is preferably synthesized by the ion exchange method for economic reasons.

The aqueous anionic colloidal silica of the present invention has a silica solid content of 5 to 50% by weight, preferably 10 to 40% by weight, a surface area of silica particles of 35 to 350 m ² / g, preferably 45 to 270 m ² / g, pH
Those having a pH of 2 to 9, preferably pH 2 to 7 are good.

If the silica solid content is less than the above amount, the economy tends to deteriorate, which is not preferable. If the silica solid content is more than the above amount, the ratio of gelation during the reaction tends to increase, which is not preferable.

If the surface area of the silica particles is smaller than the above amount, the stability of the hydrophobic organocolloidal silica tends to deteriorate, which is not preferable.If the surface area of the silica particles is larger than the above amount, the silica particles are easily precipitated, and the hydrophobic organocolloidal silica is Is liable to deteriorate in stability, which is not preferable.

If the pH is less than 2, the gelation stability of the hydrophobic organocolloidal silica tends to deteriorate, which is not preferable.
If the pH exceeds the above range, the hydrophobization reaction tends to hardly proceed, which is not preferable.

(Mixing of Hydrophobic Organic Solvent and Cationic Surfactant) In the method of the present invention, first, the hydrophobic organic solvent and the cationic surfactant are mixed.

The amount of the cationic surfactant is 1 to 50% by weight, preferably 3 to 20% by weight, based on the hydrophobic organic solvent.

If the amount of the cationic surfactant exceeds the above-mentioned amount, the unreacted cationic surfactant gels the hydrophobic organocolloidal silica and tends to deteriorate the stability, which is not preferable.

On the other hand, if the amount of the cationic surfactant is less than the above amount, the hydrophobizing reaction may be insufficient, which is not preferable.

In the present invention, at the time of mixing the hydrophobic organic solvent and the cationic surfactant, it is preferable to disperse or dissolve the cationic surfactant in the hydrophobic organic solvent. Or dissolution can be promoted.

In this case, the heating is performed at a temperature of 150 ° C. or lower, preferably 100 ° C. or lower. If the temperature is higher than the above range, the silica solid content tends to gel, which is not preferable.

(Addition of water-based anionic colloidal silica) In the method of the present invention, water-based anionic colloidal silica is added to a liquid obtained by mixing the above-mentioned hydrophobic organic solvent and a cationic surfactant. The amount of the aqueous anionic colloidal silica added is 5 to 60% by weight based on the total amount of the silica solids and the hydrophobic organic solvent as silica solids,
Preferably, the content is 10 to 50% by weight.

If the amount of the aqueous anionic colloidal silica exceeds the above-mentioned amount, the hydrophobic organocolloidal silica gels and the stability tends to deteriorate, which is not preferable. Also,
If the amount of the aqueous anionic colloidal silica is less than the above amount, the economic efficiency tends to deteriorate, which is not preferable.

In the method of the present invention, the reaction between the aqueous anionic colloidal silica and the cationic surfactant proceeds promptly only by being added at room temperature, but preferably the hydrophobic organic solvent containing the cationic surfactant is stirred. It is preferable to add while adding.

(Removal of Water) In the method of the present invention, water is removed after the reaction of the aqueous anionic colloidal silica with the cationic surfactant is started.

The removal of water can be performed during and / or after the addition of the aqueous anionic colloidal silica, but is preferably performed during and after the addition.

The removal of water may be carried out as long as there is no substantially separated aqueous phase, but preferably depends on the hydrophobicity of the organic solvent used, but generally, when the aqueous anionic colloidal silica is added, the water content of the entire system is reduced. It is preferable to perform an operation that balances the amount of addition and the amount of water removal so that the amount of water is 10% by weight or less, more preferably 5% by weight or less.

Finally, the water content of the entire system may be 5% by weight or less, more preferably 3% by weight or less, and further preferably 1% by weight or less.

If the water content at the time of adding the aqueous anionic colloidal silica exceeds the above amount, the possibility that the silica particles will precipitate tends to increase, and if the final water content of the entire system exceeds the above amount, the hydrophobicity of the product becomes poor. The gelling stability of the hydrophobic organocolloidal silica tends to decrease, which is not preferable.

The method of removing water is not limited at all, and a desired method can be appropriately selected.For example, a method such as adsorption of water by molecular sieve or zeolite, or a method such as azeotropic dehydration in a heated reflux state, and these methods may be used. Examples of combined methods can be given, and the azeotropic dehydration method is industrially suitable from the viewpoint of simplicity.

 Hereinafter, the present invention will be described in more detail with reference to examples.

〔Example〕

Example 1 A reactor equipped with a condenser, a thermometer, a stirrer, and a dropping funnel was charged with 13.3 parts by weight of a primary amine salt (C ₁₇ H ₃₃ COOCH ₂ CH ₂ NH ₃ Cl) and 140 parts by weight of xylene, 96 ° C with stirring
To obtain a homogeneous solution.

To this solution, 300 parts by weight of aqueous anionic colloidal silica [Adelite AT-20Q manufactured by Asahi Denka Kogyo Co., Ltd .: silica solids content 20% by weight, silica particle surface area 230 m ^{2 /} g, pH 3.0] 8
It was dropped over time.

During the dropwise addition of the aqueous anionic colloidal silica, the temperature was 96
Maintained at 9898 ° C. and azeotroped xylene and water. The xylene-water distillate was continuously collected through a cooler, and the operation of collecting and returning the xylene to the reaction system was repeated to perform azeotropic dehydration. The water content in the aqueous system of the aqueous anionic colloidal silica was adjusted to 2%. ４4% by weight.

After dropping, the mixture was kept at 130 ° C. for 30 minutes to interrupt azeotropic dehydration, then cooled to room temperature, passed through a paper filter and passed through a hydrophobic organocolloidal silica (in xylene) 20
9 parts by weight were obtained.

This hydrophobic organocolloidal silica was a stable low-viscosity liquid having a silica solid content of 30.6% by weight and a water content of 0.1% by weight. Further, this hydrophobic organocolloidal silica could be arbitrarily dissolved in a toluene solvent.

Example 2 Secondary amine (C ₁₂ H ₂₅ NH) as a cationic surfactant
C ₁₂ H ₂₅ ) In the same manner as in Example 1 except that 13.0 parts by weight and 140 parts by weight of toluene as a hydrophobic organic solvent were used,
202 parts by weight of hydrophobic organocolloidal silicide (in toluene) were obtained.

This hydrophobic organocolloidal silica was a stable low-viscosity liquid having a silica solid content of 30.6% by weight and a water content of 0.08% by weight. The hydrophobic organocolloidal silica could be arbitrarily dissolved in a xylene solvent.

Example 3 Tertiary amine [C ₁₇ H ₃₅ CO 3
OCH ₂ CH ₂ N (CH ₂ CH ₂ OH) ₂ ] 14.9 parts by weight and benzene 140 parts by weight as a hydrophobic organic solvent were used, and the azeotropic temperature during the dropwise addition of the aqueous anionic colloidal silica was adjusted to 72 to 74 ° C. Otherwise in the same manner as in Example 1, 212 parts by weight of hydrophobic organocolloidal silica (in benzene) was obtained.

This hydrophobic organocolloidal silica was a stable low-viscosity liquid having a silica solid content of 30.2% by weight and a water content of 0.2% by weight. The hydrophobic organocolloidal silica could be arbitrarily dissolved in a benzene solvent.

Example 4 Imidazole salt as a cationic surfactant 216 parts by weight of hydrophobic organocolloidal silica (in xylene) was obtained in the same manner as in Example 1 except that 12.3 parts by weight was used.

This hydrophobic organocolloidal silica was a stable low-viscosity liquid having a silica solid content of 30.2% by weight and a water content of 0.16% by weight. The hydrophobic organocolloidal silica could be arbitrarily dissolved in a tetrahydrofuran solvent.

Example 5 Quaternary ammonium salt having a nitrogen ring as a cationic surfactant Except that 12.6 parts by weight were used, the same procedure as in Example 1 was carried out to obtain 206 parts by weight of a hydrophobic organocolloidal silica (in xylene).

This hydrophobic organocolloidal silica was a stable low-viscosity liquid having a silica solid content of 30.4% by weight and a water content of 0.15% by weight. The hydrophobic organocolloidal silica could be arbitrarily dissolved in a methyl ethyl ketone solvent.

Example 6 Quaternary ammonium salt as a cationic surfactant Except that 12.6 parts by weight were used, 201 parts by weight of hydrophobic organocolloidal silica (in xylene) was obtained in the same manner as in Example 1.

This hydrophobic organocolloidal silica was a stable low-viscosity liquid having a silica solid content of 30.2% by weight and a water content of 0.48% by weight. Further, this hydrophobic organocolloidal silica could be arbitrarily dissolved in a toluene solvent.

〔The invention's effect〕

An effect of the present invention is to provide a method for inexpensively producing a stable hydrophobic organocolloidal silica which is easy to operate at the time of production, and has good compatibility and dispersibility with a hydrophobic organic solvent and good stability.

Claims (1)

(57) [Claims] 1. A method for producing a hydrophobic organocolloidal silica, comprising mixing a hydrophobic organic solvent and a cationic surfactant, adding an aqueous anionic colloidal silica thereto, and dehydrating the mixture.