JP6055362B2 - Method for producing porous spherical metal oxide - Google Patents

Description

  The present invention relates to a method for producing a porous spherical metal oxide.

  Porous spherical metal oxides are useful as additives for cosmetics such as foundations because they have a high oil absorption and good slipperiness. Moreover, as an application added to resin, it is useful as an antiblocking agent, a matting agent, or the like.

  As a method for producing a porous spherical metal oxide, a surfactant is used, a W phase composed of a metal oxide sol is dispersed in an organic solvent phase, a W / O emulsion is formed, and then the spherical W phase is gelled. The method of making it known is known. The spherical metal oxide obtained by this method has a high degree of circularity, and the pore diameter, specific surface area, and pore volume can be changed by controlling various production conditions. (Patent Documents 1 and 2)

JP 2000-143228 A Japanese Patent No. 4960534

  When a porous spherical metal oxide is used for applications such as cosmetics that come into contact with the skin, irritation to the skin and toxicity to the living body pose problems due to impurities contained therein. Moreover, in the use added to resin etc., the problem of deteriorating the transparency of resin arises because the impurity contained in a porous metal oxide elutes.

  In the production of the porous spherical metal oxide, in order to form a W / O emulsion, it is necessary to add a surfactant as described above. Some surfactants may have adverse effects on the skin, and others may deteriorate the transparency of the resin, and these may remain as impurities in the porous metal oxide. It may become.

  Therefore, the present invention does not adsorb the surfactant used to form the W / O emulsion in the spherical metal oxide produced via the W / O emulsion, so that it can be applied to cosmetics and resins. The object is to provide a spherical metal oxide useful as an additive.

  Further, in order to form the O phase, an organic solvent and a surfactant are required, and the procurement cost and disposal cost are considerable. A secondary object of the present invention is to reduce the cost.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have formed a W / O emulsion, gelled the W phase, and then added a hydrophilic solvent and water to demilke the milk. In addition, by heating and mixing in a state where the O phase and the W phase are separated into two phases, the surfactant adsorbed in the gel can be extracted into the O phase, whereby the above-described problems can be solved. As a result, the present invention has been completed.

That is, the present invention provides a W phase comprising a metal oxide aqueous sol and / or a metal oxoacid alkali metal salt aqueous solution in the presence of a surfactant having an HLB of 20 or less, and an O phase mainly comprising a hydrophobic organic solvent. consisting W / O emulsion is formed, after gelation of the W-phase, the phases separated into a W phase and O phase by adding a water-soluble organic solvent and water, divided into W phase and O phase and two-phase according In this state, at least the W phase is heated to 50 ° C. or higher, and then the O phase is separated and removed to recover the W phase.

The second invention, the separated O phase, is a manufacturing method of claim 1 to be reused as a hydrophobic organic solvent and a surfactant for W / O emulsion in the manufacture of the spherical metal oxide.

  According to the production method of the present invention, a spherical porous metal oxide not adsorbing a surfactant can be easily produced. When such a spherical porous metal oxide is used as an additive to cosmetics etc., there is no problem of irritation and toxicity to the skin, and when used as an additive to resins, etc. Can be used very effectively because it does not affect the transparency and the like.

By reusing the further recovered O phase, it is possible to measure also reduces the amount of the hydrophobic organic solvent and a surfactant.

  The following forms are examples of the present invention, and the present invention is not limited to these forms. Unless otherwise specified, the notation “A to B” in the numerical range means “A to B”. In this notation, when a unit is attached to only the numerical value B, the unit is also applied to the numerical value A. Hereinafter, the manufacturing method of the present invention will be described for each step.

(Metal oxide aqueous sol production process)
First, the case where the W phase is an aqueous metal oxide sol will be described. The manufacturing method of the said metal oxide sol is not specifically limited, It can carry out by a well-known method. As raw materials for producing the metal oxide sol, metal alkoxides; metal oxo acid alkali metal salts such as alkali metal silicates; various water-soluble metal salts such as water-soluble salts of inorganic acids or organic acids; Can be used.

  Specific examples of metal alkoxides that can be preferably used in the production of the spherical metal oxide of the present invention include tetramethoxysilane, tetraethoxysilane, triethoxyaluminum, triisopropoxyaluminum, tetraisopropoxytitanium, tetrabutoxytitanium, tetra Examples include propoxyzirconium and tetrabutoxyzirconium.

  Examples of the metal oxoacid alkali metal salts that can be preferably used in the production of the spherical metal oxide of the present invention include alkali metal silicates such as potassium silicate and sodium silicate, and the chemical formula is represented by the following formula ( 2).

m (M ₂ O) · n (SiO ₂ ) (2)
[In Formula (2), m and n each independently represent a positive integer, and M represents an alkali metal atom. ]
As other metal oxo acid alkali metal salts that can be used in the production of the spherical metal oxide of the present invention, alkali metal salts of metal oxo acids such as aluminate, vanadic acid, titanic acid, tungstic acid, preferably sodium salts, And potassium salts.

  Examples of water-soluble metal salts of inorganic or organic acids that can be preferably used in the production of the spherical metal oxide of the present invention include iron (III) chloride, zinc chloride, tin chloride (II or IV), magnesium chloride, and copper chloride. (II), magnesium nitrate, zinc nitrate, calcium nitrate, barium nitrate, strontium nitrate, iron (III) nitrate, copper (II) nitrate, magnesium acetate, calcium acetate, vanadium chloride (IV) and the like.

  Among the raw materials for producing the metal oxide sol, an alkali metal silicate can be preferably used from the viewpoint of inexpensiveness, and sodium silicate which is easily available is preferable. In the following, sodium silicate is used as a raw material for preparing a metal oxide sol, and a mode of producing silica as a metal oxide will be described as a representative example, but even when other metal sources are used, the aqueous sol is prepared by a known method. Creation and gelation can be performed.

When obtaining an aqueous metal oxide sol using an alkali metal silicate such as sodium silicate, an aqueous solution of the alkali metal silicate (note: also commercially available) is used with a mineral acid such as hydrochloric acid or sulfuric acid. Alkali metal silicate by a method using a cation exchange resin in which the counter ion is a hydrogen ion (H ⁺ ) (hereinafter sometimes referred to as “acid type cation exchange resin”) A silica sol can be prepared by replacing an alkali metal atom in an aqueous solution with a hydrogen atom.

  As a method for preparing silica sol by neutralizing with the above acid, an aqueous solution of an alkali metal silicate salt is added to an aqueous acid solution while stirring the aqueous solution, or an aqueous acid solution and an alkali silicate solution. There is a method in which a metal salt aqueous solution is collided and mixed in a pipe (for example, see Japanese Patent Publication No. 4-54619). The amount of acid used is preferably 1.05 to 1.2 as the molar ratio of hydrogen ions to the alkali metal content of the alkali metal silicate. When the amount of the acid is within this range, the pH of the prepared silica sol is about 1 to 3.

  The method for preparing the silica sol using the acid type cation exchange resin can be performed by a known method. For example, a method in which an aqueous solution of an alkali metal silicate having an appropriate concentration is passed through a packed bed filled with an acid type cation exchange resin, or an acid type cation exchange resin is added to an aqueous solution of an alkali metal silicate salt and A method of separating the acid-type cation exchange resin by mixing, chemically adsorbing alkali metal ions to the cation exchange resin and removing the alkali metal ions from the solution and then filtering off, etc. can be mentioned. At that time, the amount of the acid type cation exchange resin to be used needs to be equal to or more than the amount capable of exchanging the alkali metal contained in the solution.

  As said acid type cation exchange resin, a well-known thing can be especially used without a restriction | limiting. For example, an ion exchange resin such as a styrene type, an acrylic type, or a methacryl type that has a sulfonic acid group or a carboxyl group as an ion exchange group can be used. Among these, a so-called strong acid type cation exchange resin having a sulfonic acid group can be suitably used.

  In addition, after using said acid type cation exchange resin for replacement | exchange of an alkali metal, it can regenerate | regenerate by making it contact with a well-known method, for example, a sulfuric acid or hydrochloric acid. The amount of acid used for regeneration is usually 2 to 10 times the exchange capacity of the ion exchange resin.

The concentration of the silica sol prepared by the above method is such that the gelation is completed in a relatively short time, and in order to sufficiently form the skeleton structure of the silica particles and suppress shrinkage during drying, The concentration (SiO ₂ equivalent concentration) is preferably 50 g / L or more. On the other hand, in order to relatively reduce the density of silica particles and increase the pore volume per unit weight, it is preferably 160 g / L or less, and more preferably 100 g / L or less. .

(Alkali metal salt metal oxo acid solution)
When the W phase is a metal oxoacid alkali metal salt, the same metal oxoacid alkali metal salt as described above may be dissolved in water to form an aqueous solution. The same applies to the concentration. If there is a commercial product such as sodium silicate, it may be used as it is or after dilution.

  In this method, W phase solification and gelation are continuously performed after the W / O emulsion formation step described below.

(W / O emulsion formation process)
The production method of the present invention includes a step of forming a W / O emulsion. That is, an emulsion is formed using the above-described metal oxide sol or alkali metal metal oxoacid as a dispersoid and a hydrophobic solvent as a dispersion medium. By forming such a W / O emulsion, the dispersoid becomes spherical due to surface tension or the like, and thus a spherical gelled body can be obtained by gelling in the spherical shape. Thus, it becomes possible to manufacture a porous spherical metal oxide having a high degree of circularity through the emulsion forming step of forming a W / O emulsion.

  In the production method of the present invention, as the W phase of the W / O emulsion, the aqueous metal oxide sol and / or the metal oxoacid alkali metal salt described above are used.

  In the production of the spherical metal oxide of the present invention, the hydrophobic solvent used for the O phase of the W / O emulsion is hydrophobic enough to form an emulsion with an aqueous metal oxide sol and / or an alkali metal oxo acid alkali metal salt solution. Any solvent may be used. As such a solvent, for example, organic solvents such as hydrocarbons and halogenated hydrocarbons can be used. More specifically, hexane, heptane, octane, nonane, decane, dichloromethane, chloroform, carbon tetrachloride, dichloropropane and the like can be mentioned. Among these, hexane and heptane having an appropriate viscosity can be particularly preferably used. If necessary, a plurality of solvents may be mixed and used. In addition, a hydrophilic solvent such as lower alcohols can be used together (used as a mixed solvent) as long as it can form an aqueous silica sol and a W / O emulsion.

  The amount of the hydrophobic solvent to be used is not particularly limited as long as the emulsion is an amount that is W / O type. However, generally, the amount of the hydrophobic solvent is about 1 to 10 parts by volume with respect to 1 part by volume of the W phase.

  In the production method of the present invention, a surfactant is added when the above W / O emulsion is formed. As the surfactant to be used, any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant can be used. Among these, nonionic surfactants are preferable because they can easily form a W / O emulsion.

  In the production method of the present invention, since the metal oxide sol and the metal oxoacid alkali metal salt solution are aqueous, those having an HLB value of 20 or less indicating the degree of hydrophilicity and hydrophobicity of the surfactant. Is used. When the HLB value exceeds this range, the surfactant becomes hydrophilic, so that it becomes difficult to perform extraction when the surfactant is extracted and removed by heating to a hydrophobic solvent, which will be described later. It becomes impossible to obtain a spherical metal oxide not adsorbing the surfactant. In order to suitably prepare the W / O emulsion, a surfactant having an HLB value of 3 or more and 5 or less can be used.

  In the present invention, the “HLB value” means an HLB value according to the Griffin method. As described above, in the present invention, the shape of the metal oxide particles is substantially determined by the shape of the droplets of the W / O emulsion. By using a surfactant having an HLB value within the above preferred range, it becomes easy to make the W / O emulsion stably present. Specific examples of the surfactant that can be suitably used include sorbitan monooleate (HLB: 4.3), sorbitan monostearate (HLB: 4.7), sorbitan monosesquiolate (HLB: 3.7), and the like. Of sorbitan fatty acid esters.

  The amount of the surfactant having an HLB of 20 or less is not different from the general amount when forming a W / O emulsion. Specifically, a range of 0.05 g or more and 10 g or less can be suitably employed with respect to 100 ml of the aqueous silica sol. If the amount of the surfactant used is large, the droplets of the W / O emulsion are likely to become finer. Conversely, if the amount of the surfactant used is small, the droplets of the W / O emulsion are likely to be larger. Therefore, it is possible to adjust the average particle diameter of the spherical metal oxide by increasing or decreasing the amount of the surfactant used.

  As a method of dispersing the metal oxide sol or the metal oxoacid alkali metal salt or the like in the hydrophobic solvent when forming the W / O emulsion, a known method for forming the W / O emulsion can be employed. . From the viewpoint of ease of industrial production and the like, emulsion formation by mechanical emulsification is preferred, and specific examples include a method using a mixer, a homogenizer, and the like. Preferably, a homogenizer can be used. Since the particle size of the dispersed metal oxide sol droplet is related to the particle size of the spherical metal oxide, it is preferable to adjust the liquid particle size of the sol so as to be the target particle size.

(Gelification process)
In the production method of the present invention, the W phase is gelled after the formation of the W / O emulsion. The gelation can be performed by a known method.

  When an aqueous sol of metal oxide is used as the W phase of the W / O emulsion, for example, a method of heating to a high temperature, or the pH of the metal oxide sol is 2 to 9, preferably 4 to 8, more preferably The method of adding a base is mentioned so that it may become 5-6. It is preferable to cause gelation by pH adjustment in that gelation can be performed quickly and at low energy costs.

  Specific examples of the base include ammonia; tetraalkylammonium hydroxides such as tetramethylammonium hydroxide (TMAH); amines such as trimethylamine; alkali hydroxides such as sodium hydroxide; sodium carbonate, sodium hydrogencarbonate, etc. Alkali metal carbonates; and alkali metal silicates. When adjusting the pH with an alkali metal silicate, the concentration of the silica component is the total concentration of the silica source used for the preparation of the aqueous silica sol and the silica component derived from the alkali metal silicate used for the pH adjustment. Means.

  Among these bases, ammonia, tetraalkylammonium hydroxides, or amines are preferably used, and ammonia is particularly preferable in that no metal element is mixed in and no water washing operation is required. When ammonia is used, it may be blown into the W / O emulsion as a gas, or may be added as aqueous ammonia. However, it is more preferable to add as ammonia water in terms of easy pH fine adjustment.

  Further, the method of adjusting pH using a metal oxoacid alkali metal salt requires a separate facility for alkali when the same metal oxoacid alkali metal salt is used when preparing the metal oxide sol. Has the advantage of not.

  When an aqueous metal oxo acid alkali metal salt solution is used as the W phase of the W / O emulsion, the pH of the aqueous solution containing the metal oxo acid alkali metal salt is 2 to 9, preferably 4 to 8, more preferably 5 to 6. It can be performed by adding an acid.

  Specific examples of using the acid used for pH adjustment during the gelation include mineral acids such as hydrochloric acid and sulfuric acid; organic acids such as formic acid, acetic acid, citric acid and oxalic acid; carbon dioxide gas and the like.

  Such pH adjustment can be easily performed by adding a base or an acid to the emulsion while stirring with a mixer or the like to maintain the W / O emulsion formation state. The strength of the stirring may be as strong as mixing of the W / O emulsion and the base or acid occurs.

  In addition, it is preferable to measure the amount of the base or acid that reaches the target pH in advance and add the amount of the base or acid to the W / O emulsion. Measurement of the amount of base or acid that achieves the target pH is obtained by taking a certain amount of a metal oxide sol or metal oxo acid alkali metal salt aqueous solution used in the W / O emulsion and measuring the pH with a pH meter. It can be carried out by adding a base or an acid used for gelation and measuring the amount of the base or acid that achieves the target pH.

The time required for the above gelation depends on the type and temperature of the W phase, but when silica sol is used for the W phase, the pH is 5, the silica concentration in the silica sol (in terms of SiO ₂ ) is 80 g / L, and the temperature is 50 ° C. In some cases, gelation occurs after a few minutes.

  Further, since the dispersoid changes from a liquid state to a solid state after gelation, the system is not a W / O emulsion but a dispersion (suspension) in which a solid (gelled body) is dispersed in a hydrophobic solvent.

(WO phase separation process)
In the production method of the present invention, WO phase separation is performed following gelation. The WO phase separation is an operation that separates the dispersion solvent into an O phase and a W phase, and is generally referred to as milking. Here, the gelled body obtained by the gelation step is present on the separated W phase side. In the present invention, the WO phase separation is performed by adding a certain amount of water and a water-soluble organic solvent to the emulsion.

  Examples of the water-soluble organic solvent include acetone, methanol, ethanol, isopropyl alcohol and the like. Of these, isopropyl alcohol can be suitably used because it is effective in increasing the efficiency of the treatment even in the silylation treatment described later.

  The amount of the water-soluble organic solvent added is preferably adjusted according to the type and amount of the surfactant having an HLB of 20 or less used during the formation of the emulsion. For example, when sorbitan monooleate is used as the surfactant, the addition of a water-soluble organic solvent having a mass of about 1/6 to 1/2 times the total amount of the O phase makes it easy to demilk. It can be carried out. In addition, when the surfactant described later is extracted following the separation of the W phase, the amount of the water-soluble organic solvent affects the efficiency when the surfactant is extracted. It is preferable to adjust the addition amount so that the surfactant can be extracted. In order to perform the extraction efficiently, it is preferable to add a water-soluble organic solvent about 1/6 to 1/4 times the total amount of the O phase.

  Further, the amount of water added simultaneously with the water-soluble organic solvent needs to be added to such an extent that the fluidity of the gel contained on the W phase side is maintained, and is 1/4 to 2 times the volume of the gel. It is preferable to add a degree.

(Warming (surfactant extraction and removal) process)
In the method for producing a spherical metal oxide of the present invention, subsequent to the separation of the W phase, the surfactant is extracted and removed to the O phase by heating. The surfactant used in the present invention has an HLB of 20 or less and is more easily dissolved in a hydrophobic solvent forming the O phase than the W phase. It is adsorbed on the surface.

  Therefore, if this extraction and removal step is not performed, the resulting spherical metal oxide will contain the surfactant used. Therefore, a spherical metal oxide not adsorbing the surfactant can be obtained by performing an extraction and removal operation of the surfactant. In the extraction and removal of the surfactant, at least the W phase is heated to 50 ° C. or higher in the state where the W phase and the O phase are separated into two phases by the above-mentioned milking. In order to increase the efficiency, stirring with a mixer or the like is also preferable.

  As a temperature range for heating, at least the W phase needs to be 50 ° C. or more, preferably about 50 to 80 ° C., more preferably about 60 to 70 ° C. Of course, the O phase may be heated together. A feature of the present invention is that such a high temperature is applied. At about room temperature, for example, even if the solvent is changed a plurality of times, the surfactant cannot be easily removed.

When stirring with a mixer or the like, the stirring power is 0.1 to 3.0 kW / m ³ , preferably 0.5 to 1.5 kW / m ³ , and the stirring time is 0.5 to 24 hours, preferably It is about 1 to 5 hours.

  In addition, the above-described heating operation simultaneously proceeds with aging (aging) performed for the purpose of increasing the strength of the particles constituting the spherical metal oxide of the present invention. Further aging of the gelation reaction (dehydration condensation reaction) by this aging is preferable in obtaining a spherical metal oxide having a large amount of pores. In addition, you may age | cure | ripen as a separate operation from extraction by heating in the state which does not stir. The ripening as the separate operation can be performed before and / or after the extraction of the surfactant.

  As a means for confirming whether or not the extraction of the surfactant has been sufficiently performed, a method of measuring the amount of the surfactant contained in the O phase side by NMR, gas chromatography, liquid chromatography or the like can be mentioned.

(W phase recovery process)
In the method for producing a spherical metal oxide according to the present invention, the W phase containing the gelled body is recovered after the surfactant extraction and removal step. Specifically, the O phase can be separated and removed by decantation or the like.

  Further, the surfactant is recovered in the separated O phase, and can be reused as a hydrophobic organic solvent and a surfactant for preparing a W / O emulsion. Hydrophobic organic solvents include several percent of hydrophilic organic solvents added for WO phase separation, but this is usually not a problem for the formation of W / O emulsions. If the amount of the hydrophilic organic solvent added during the WO phase separation is reduced to such an extent that the WO phase separation occurs, a W / O emulsion can be easily formed even when reused. Moreover, what is necessary is just to perform operation of isolate | separating a hydrophilic organic solvent and a hydrophobic organic solvent by operation, such as distillation. Rinsing with water is also possible.

  Moreover, although the hydrophobic organic solvent may volatilize, it is preferable to adjust the amount by adding it in a timely manner.

(Gelified body recovery step-1)
The gel contained in the W phase is recovered by filtration, and if necessary, by removing salts such as sulfates and carbonates by washing with water and drying, a spherical metal oxide can be obtained. .

(Hydrophobicization process)
In addition, after performing the extraction and removal of the surfactant and the aging operation (heating step), a treatment with a hydrophobizing agent can be performed before the gelled body recovery step. When the treatment with the hydrophobizing agent is performed, it is possible to suppress shrinkage that occurs during drying, so that a spherical metal oxide having a larger pore volume can be obtained. Further, since the produced spherical metal oxide becomes hydrophobic, it has little moisture adsorption that causes deterioration over time, and is well-familiar with hydrophobic resins and the like.

  When the treatment with the hydrophobizing agent is performed, the treatment with the hydrophobizing agent can be efficiently performed by collecting the W phase (removing the O phase) prior to the treatment. Here, the W phase and the O phase do not need to be separated by 100%, but the amount of the O phase remaining after the removal is preferably 30 wt% or less, more preferably 20 wt% or less.

In the production method of the present invention, as the hydrophobizing agent used for the hydrophobizing treatment, what is generally called a silylating agent can be suitably used. The silylating agent is a hydroxy group present on the surface of the metal oxide:
M-OH (1)
[In formula (1), M represents a metal atom. In formula (1), the remaining valence of M is omitted. ]
React with, this _{(M-O-) (4-} n) SiR n (2)
[In Formula (2), n is an integer of 1-3, R is a hydrocarbon group, and when n is 2 or more, a plurality of R may be the same or different from each other. ]
An example is a silylating agent that can be converted to. By performing silylation treatment using such a silylating agent, the hydroxy group on the surface of the metal oxide is endcapped with a hydrophobic silyl group and inactivated, so dehydration between the surface hydroxy groups The condensation reaction can be suppressed. Therefore, since drying shrinkage can be suppressed, it becomes possible to obtain spherical metal oxidation having a large BJH pore volume.

  As the silylating agent, compounds represented by the following general formulas (3) to (5) are known.

R _n SiX _(4-n) (3)
[In formula (3), n represents an integer of 1 to 3; R represents a hydrophobic group such as a hydrocarbon group; X represents a molecule in which a bond with a Si atom is cleaved in a reaction with a compound having a hydroxy group. Represents a group (leaving group) that can be removed from the group. When n is 2 or more, a plurality of R may be the same or different. When n is 2 or less, the plurality of Xs may be the same or different. ]

[In Formula (4), R ¹ represents an alkylene group; R ² and R ³ each independently represent a hydrocarbon group; R ⁴ and R ⁵ each independently represent a hydrogen atom or a hydrocarbon group. ]

[In Formula (5), R ⁶ and R ⁷ each independently represent a hydrocarbon group, and m represents an integer of 3 to 6. A plurality of R ⁶ may be the same or different. A plurality of R ⁷ may be the same or different. ]
In the above formula (3), R is a hydrocarbon group, preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrocarbon group having 1 to 4 carbon atoms, and particularly preferably a methyl group. is there.

The leaving group represented by X includes a halogen atom such as chlorine or bromine; an alkoxy group such as methoxy group or ethoxy group; a group represented by —NH—SiR ₃ (wherein R represents R in formula (2)) And the like).

  Specific examples of the silylating agent represented by the above formula (3) include chlorotrimethylsilane, dichlorodimethylsilane, trichloromethylsilane, monomethyltrimethoxysilane, monomethyltriethoxysilane, hexamethyldisilazane and the like. From the viewpoint of good reactivity, chlorotrimethylsilane, dichlorodimethylsilane, trichloromethylsilane and / or hexamethyldisilazane are particularly preferable.

Depending on the number of leaving groups X (4-n), the number of bonds with hydroxy groups on the metal oxide skeleton varies. For example, if n is 2, then:
(MO) ₂ SiR ₂ (6)
This results in a bond. If n is 3, then:
M-O-SiR ₃ (7)
This results in a bond. Thus, a silylation process is made | formed by a hydroxyl group being silylated.

In the above formula (4), R ¹ is an alkylene group, preferably an alkylene group having 2 to 8 carbon atoms, and particularly preferably an alkylene group having 2 to 3 carbon atoms.

In the formula (4), R ² and R ³ are each independently a hydrocarbon group, and preferred groups include the same groups as R in the formula (2). R ⁴ represents a hydrogen atom or a hydrocarbon group, and when it is a hydrocarbon group, preferred groups include the same groups as R in formula (2). When the gelated product is treated with the compound represented by the formula (4) (cyclic silazane), the Si—N bond is cleaved by reaction with the hydroxy group, so that the metal oxide (here, the gelled product) It is silica.) On the surface of the skeleton, (MO) ₂ SiR ² R ³ (8)
This results in a bond. Thus, also by the cyclic silazanes of the above formula (4), the hydroxy group is silylated and subjected to silylation treatment.

  Specific examples of the cyclic silazanes represented by the above formula (4) include hexamethylcyclotrisilazane and octamethylcyclotetrasilazane.

In the formula (5), R ⁶ and R ⁷ are each independently a hydrocarbon group, and preferred groups include the same groups as R in the formula (2). m shows the integer of 3-6. When the gelled body is treated with the compound represented by the formula (5) (cyclic siloxane), on the surface of the metal oxide skeleton in the gelled body,
(MO) ₂ SiR ⁶ R ⁷ (9)
This results in a bond. Thus, also by the cyclic siloxanes of the above formula (5), the hydroxy group is silylated and subjected to silylation treatment.

  Specific examples of the cyclic siloxanes represented by the above formula (5) include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane and the like.

  The amount of the treating agent used in the above silylation treatment depends on the kind of the treating agent. For example, when the metal oxide is silica and dimethyldichlorosilane is used as the treating agent, the metal oxide (Silica) 30 to 150 parts by weight is suitable for 100 parts by weight.

  The conditions for the above-described hydrophobizing treatment can be performed by adding a hydrophobizing agent to the separated W phase and reacting for a predetermined time. For example, when the metal oxide is silica, dimethyldichlorosilane is used as the silylation treatment agent, and the treatment temperature is 50 ° C., it can be carried out by holding for about 4 to 12 hours or more. Octamethylcyclotetrasiloxane When the processing temperature is 70 ° C., it can be carried out by holding for about 6 to 12 hours or more.

  Moreover, when using cyclic siloxanes, such as octamethyl siloxane tetrasiloxane, as a silylation processing agent, pH of a solution shall be 0.3-1.0 by adding hydrochloric acid, and the efficiency of reaction improves. Preferred above.

  In the silylation treatment step, it is preferable to add a water-soluble organic solvent for the purpose of increasing the solubility of the treatment agent in the W phase and increasing the reaction efficiency. Examples of the water-soluble organic solvent include acetone, methanol, ethanol, isopropyl alcohol and the like. Of these, isopropyl alcohol can be preferably used.

  The water-soluble organic solvent is preferably added so that the concentration in the W phase is about 20 to 80 wt%. If a water-soluble organic solvent is added during the previous W phase separation step, it can be used as it is in the hydrophobization process, and further added with a water-soluble organic solvent to a suitable concentration. You can also

(Gelified body extraction process)
In the production method of the present invention, when the hydrophobization treatment is performed by the above method, the spherical metal oxide is in a state dispersed in an aqueous solvent. In order to recover the spherical metal oxide from this dispersion, it may be filtered as it is, but preferably the gelled product is once extracted into a hydrophobic organic solvent and then filtered. Thus, once extracted into a hydrophobic organic solvent, it becomes possible to obtain a spherical metal oxide having a larger pore volume.

  As the hydrophobic organic solvent used for the gelled body extraction, those having a small surface tension are preferable in order to prevent drying shrinkage during the subsequent drying step. Specifically, hexane, heptane, dichloromethane, methyl ethyl ketone, toluene and the like can be used, and preferably hexane, heptane and toluene can be used.

  Specifically, the hydrophobic organic solvent is added to the aqueous dispersion of the gelated hydrogel and the gelled hydrogel is extracted on the hydrophobic organic solvent side by stirring. . The amount of the hydrophobic organic solvent to be used is only required to be separated again into two layers of the O phase and the W phase, but is generally about 100 to 200 parts by volume with respect to 100 parts by volume of the aqueous dispersion. .

  After the extraction into the hydrophobic organic solvent, the organic solvent is removed with water or an aqueous solution of alcohol in order to remove the salt contained in the gelated product, the sulfate contained in the hydrophobic organic solvent, or the like. It is preferable to perform washing. This washing operation can be performed by a known method. In order to increase the cleaning efficiency, it is preferable to use an aqueous solution of about several tens wt% of isopropyl alcohol. Further, it is preferable to increase the temperature within a range not exceeding the boiling point of the hydrophobic organic solvent in order to increase the cleaning efficiency. Usually, it can carry out in the range of 50-70 degreeC.

(Gelified body recovery step-2)
In the production method of the present invention, when the gelled body extraction step is performed, the gelled body recovery step can be subsequently performed. That is, the gel dispersed in the hydrophobic organic solvent is filtered off, and the hydrophobic organic solvent is removed (dried). The drying temperature is preferably not less than the boiling point of the solvent and not more than the decomposition temperature of the surface treatment agent, and the pressure is preferably carried out under normal pressure or reduced pressure.

  In the above description of the present invention, the method for producing a spherical metal oxide in which the metal oxide is mainly silica is mainly exemplified, but the present invention is not limited to this form.

  For example, when a silica-titania composite oxide is to be obtained by the method using the metal alkoxide described above as a raw material, an alkoxysilane such as tetraethoxysilane and an alkoxytitanium such as tetrabutoxytitanium are mixed at a desired molar ratio. It can be hydrolyzed under acidic conditions to obtain an aqueous sol, which can be produced as a W phase by the same procedure as described above.

  In the above-described metal oxide sol preparation step, for example, a mixed sol is prepared by allowing an acid to act on a mixture of sodium silicate and sodium aluminate, or by allowing an acid to act on sodium silicate. After the procedure of preparing the mixed sol by mixing the silica sol and the alumina sol obtained by hydrolysis of aluminum triethoxide, the mixed sol is subjected to the steps after the emulsion formation step, whereby the metal oxide is obtained. It is also possible to produce a spherical metal oxide in the form of a silica-alumina composite oxide.

  Further, in the form in which the metal oxide is a composite metal oxide other than the silica-alumina composite oxide, for example, a plurality of metal hydroxide sols individually prepared by the above-described known methods are mixed at an appropriate mixing ratio. Can be produced by preparing a mixed sol having a desired metal composition ratio and subjecting the mixed sol to the steps after the emulsion forming step.

  According to the production method of the present invention described above, the obtained metal oxide does not contain a surfactant. Whether or not the surfactant is adsorbed can be confirmed by measuring the spherical metal oxide to be measured by solid-state NMR and checking whether or not the peak of the surfactant exists in the obtained spectrum. it can.

  The solid-state NMR conditions are described in detail. A substance whose chemical shift does not overlap with the surfactant as an internal standard is added to the silica to be measured, and the surfactant is determined according to the peak ratio between the internal standard and the surfactant. Measure the amount of At this time, a calibration curve is prepared in advance using a sample whose adsorption amount of the surfactant is known. The nucleus to be measured is C13, and a CP / MAS (Cross Polarization / Magic Angling Spinning) method is used. As the internal standard, adamantane, glycine, hexamethylbenzene or the like can be suitably used.

  The spherical metal oxide obtained by the production method of the present invention is powdery after the drying. The individual individual particles (secondary particles) constituting the powder usually have an average circularity of 0.8 or more. More preferably, it is 0.85 or more. The “average circularity” refers to an SEM image observed with secondary electron detection, low acceleration voltage (1 kV to 3 kV), and magnification 1000 times using a scanning electron microscope (SEM). A value C (circularity) defined by Equation (10) is obtained (image analysis), and this circularity C is a value obtained as an arithmetic average value for 2000 or more particles (image analysis method). At this time, the particle group forming one aggregated particle is counted as one particle.

C = 4πS / L ² (10)
[In Formula (10), S represents the area (projection area) which the said particle occupies in an image. L represents the length (peripheral length) of the outer periphery of the particle in the image. ]
As the average circularity is larger than 0.8 and approaches 1, the individual particles constituting the spherical metal oxide have a shape close to a true sphere, and the aggregated particles also decrease. Therefore, if the average circularity is high, for example, when used as a cosmetic additive, the rolling property is improved and an excellent tactile sensation is obtained.

The ratio surface area by the BET method (BET specific surface area) is usually 400 to 1000 m ² / g, which is often 400~850m ² / g. It shows that the particle diameter of the primary particle which comprises the porous structure (network structure) of the independent particle | grains (secondary particle) of spherical metal oxide is so small that a specific surface area is large. Therefore, the larger the BET specific surface area, the higher the thickening effect when used as a cosmetic additive. This makes it possible to prevent dripping when cosmetics are applied to the skin or hair. However, it is difficult to obtain a large product exceeding 1000 m ² / g even by the method of the present invention.

  Usually, the pore volume by the BJH method is 2 to 8 mL / g, and the median diameter in the particle size distribution by laser diffraction measurement is in the range of 1 to 50 μm.

  Hereinafter, examples will be shown to specifically describe the present invention. However, the present invention is not limited only to these examples.

<Evaluation method>
The spherical metal oxide manufactured in Examples 1 to 4 and Comparative Examples 1 and 2 was tested for the following items.

(Measurement of surfactant adsorption)
The adsorption amount of the surfactant was measured by solid-state NMR (AVANCE II 500 manufactured by Bruker Biospin). A 4 mm cell was used, the MAS rotation speed was 7000 Hz, and 5% glycine was added as an internal standard substance. The number of integrations was 8192 times.

(Average circularity and median diameter measurement by image analysis)
SEM images of 2000 or more spherical metal oxides observed at a magnification of 1000 using SEM (S-5500, Hitachi High-Technologies S-5500, acceleration voltage 3.0 kV, secondary electron detection) are analyzed, and the average circularity, And the median diameter was calculated. The average circularity was calculated according to the following formula.

C = 4πS / L ²
[In the above formula, S represents the area (projected area) occupied by the particles in the image. L represents the length (peripheral length) of the outer periphery of the particle in the image. ]
(Measurement of particle size distribution and median diameter by laser diffraction)
0.1 g of the spherical metal oxide was added to 40 ml of isopropyl alcohol and dispersed for 6 minutes at an output of 100 w using UT-105S manufactured by Sharp Manufacturing Co., Ltd. The particle size distribution of the dispersion was measured using Microtrac MT3000 manufactured by JGC apparatus Co., Ltd. The refractive index of the solvent was 1.38, and the refractive index of the particles was 1.46. The median diameter with respect to the volume distribution was evaluated from the obtained particle size distribution.

(Measurement of other physical properties)
The BET specific surface area, the BJH pore volume, and the pore radius peak were measured by BELSORP-mini manufactured by Nippon Bell Co., Ltd. As a pretreatment for measurement, a sample to be measured was dried at 200 ° C. for 3 hours or more under a vacuum of 1 kPa or less. Thereafter, an adsorption isotherm only on the nitrogen adsorption side at the liquid nitrogen temperature was obtained. Then, it analyzed by BET method and BJH method. The peak of the pore radius is a value of the pore radius at which the cumulative pore volume (volume distribution curve) based on the logarithm of the pore radius takes the maximum peak value.

<Example 1>
(Metal oxide sol production process)
A solution of No. 3 sodium silicate was diluted and adjusted to a concentration of SiO ₂ : 150 g / L and Na ₂ O: 51 g / L. In addition, sulfuric acid having a concentration adjusted to 103 g / L was prepared. A silica sol was prepared by adding sodium silicate to 100 ml of sulfuric acid while stirring until the pH reached 3.

(W / O emulsion formation process)
By separating 100 mL of silica sol, adding 241 ml of heptane in which 2.4 g of sorbitan monooleate was dissolved, and using a homogenizer (manufactured by IKA, T25BS1), the mixture was stirred for 5 minutes under the condition of 11000 rotations / minute. A / O emulsion was obtained.

(Gelification process)
To the obtained W / O emulsion, SiO ₂ : 150 g / L, Na ₂ O: 51 g / L sodium silicate was added to adjust the pH to 5.

(WO phase separation process)
Isopropyl alcohol (38 mL) and water (50 mL) were added, and the O phase and W phase were separated while stirring with a stirring blade.

(Surfactant extraction process)
Surfactant extraction and gel ripening by using a 4-paddle blade with a blade diameter of 60 mm, a blade width of 20 mm, and an inclination angle of 45 degrees and stirring in a water bath at 60 ° C. for 3 hours while stirring at 300 rpm. Went. The amount of polyoxyethylene sorbitan monooleate contained in the heptane phase was analyzed, and it was confirmed that the total amount added was extracted into the heptane phase.

(W phase recovery process)
The O phase and the W phase were separated by decantation, and only the W phase was recovered.

(Gelified body recovery step-1)
After decanting the W phase and discarding the supernatant, the operation of adding water and stirring was repeated until the water conductivity of the supernatant was 100 μS / cm or less to remove the salt contained in the gel. The gelled body was recovered by suction filtration of the W phase, and dried by a vacuum dryer at 150 ° C. for 12 hours. The physical properties of the spherical metal oxide thus obtained are shown in Table 1.

<Example 2>
Subsequent to the W phase recovery step of Example 1, the following hydrophobization treatment step, gelled body extraction step, gelled body recovery, and drying step were performed.

(Hydrophobicization process)
Hydrophobic treatment was performed by adding 108 ml of isopropyl alcohol, 10 g of 35% hydrochloric acid, and 4 g of octamethylcyclotetrasiloxane, and maintaining in a water bath at 70 ° C. for 24 hours while stirring.

(Gelified body extraction process)
After the treatment, 100 mL of toluene was added while stirring with a stirring blade to extract the gelled product, and the toluene phase was washed with 100 mL of ion-exchanged water three times.

(Gelified body recovery step-2)
The obtained gelled product after the hydrophobization treatment was separated by a suction filter. The gelled body was dried with a vacuum dryer at 150 ° C. for 12 hours. The physical properties of the spherical metal oxide thus obtained are shown in Table 1.

<Example 3>
In the gelation step, the same operation as in Example 2 was performed except that the pH to be adjusted was changed from 5 to 6. Table 1 shows the physical properties of the obtained spherical metal oxide.

<Example 4>
In the W / O emulsion formation step, the same operation as in Example 3 was performed except that the amount of sorbitan monooleate added was 1.2 g and the stirring speed with a homogenizer was 3400 revolutions. Table 1 shows the physical properties of the obtained spherical metal oxide.

<Example 5>
As the O phase and the surfactant in forming the W / O emulsion, those recovered during the WO phase separation step of Example 2 were used. The composition of the recovered O phase was 155 g (227 ml) of heptane, 6 g (8 ml) of isopropyl alcohol, and 2.4 g of sorbitan monooleate. 10 g (15 ml) of heptane was added to the recovered O phase and used as the O phase in the W / O emulsion formation of this example. About other than that, it operated similarly to Example 2. FIG. Table 1 shows the physical properties of the obtained spherical metal oxide.

<Comparative Example 1>
The operation was performed in the same manner as in Example 1 except that the surfactant extraction step was not performed. Table 1 shows the physical properties of the obtained spherical metal oxide.

<Comparative example 2>
Before carrying out the gel ripening step, the W phase recovery step is carried out, and then the gel ripening step is carried out by holding in a water bath at 60 ° C. for 3 hours while stirring, that is, the surfactant is not extracted. The operation was performed in the same manner as in Example 3 except that. Table 1 shows the physical properties of the obtained spherical metal oxide.

<Comparative Example 3>
A spherical metal oxide was produced according to the method described in Japanese Patent No. 4960534.

That is, the solution of No. 3 sodium silicate was diluted and adjusted to a concentration of SiO ₂ : 150 g / L and Na ₂ O: 51 g / L. In addition, sulfuric acid having a concentration adjusted to 103 g / L was prepared. Silica sol was prepared by impact-mixing in a pipe under the conditions of a sodium silicate solution of 1.08 L / min and sulfuric acid of 0.99 L / min. The obtained silica sol had a pH of 2.9.

  To this silica sol, 600 mL of hexane was added, 1.6 g of sorbitan monooleate was added, and the mixture was stirred for 4 minutes under the condition of 11000 rotation using a homogenizer (manufactured by IKA, T25BS1) to form a W / O emulsion. While stirring with a mixer, 5% aqueous ammonia was added to the emulsion to adjust the pH in the sol to 6. After stirring for 5 minutes, 400 ml of water was added, the aqueous layer was separated, and a gel was obtained.

  The gel was placed in a column and washed with 2 L of ion exchange water. Finally, the electrical conductivity of the wash water discharged from the column was 42 μS / cm. Thereafter, the solvent was replaced with 2 L of ethanol, and then the solvent was replaced with 1.2 L of hexane. By adding hexane to the gel, the total volume was made 800 ml, and 40 g of trimethylchlorosilane was added. Then, it hold | maintained at 50 degreeC for 24 hours.

  The hydrophobized gel was separated by suction filtration and washed with 800 ml of hexane. The gel was dried under normal pressure while flowing nitrogen. The drying temperature and time were 40 ° C. for 3 hours, 50 ° C. for 2 hours, and 150 ° C. for 12 hours.

The spherical metal oxide thus obtained contained 1 wt% of a surfactant. Other physical properties include a specific surface area of 710 m ² / g, a pore volume of 5.6 ml / g, a pore radius peak of 22 nm, a median diameter of particle size distribution by laser diffraction of 15 μm, and a median diameter by image analysis. Was 8 μm. The average circularity was 0.90.

Claims (2)

W / O emulsion comprising a W phase comprising a metal oxide aqueous sol and / or a metal oxoacid alkali metal salt aqueous solution and an O phase mainly comprising a hydrophobic organic solvent in the presence of a surfactant having an HLB of 20 or less. After the W phase is gelled, a water-soluble organic solvent and water are added to cause phase separation into the W phase and the O phase, and at least the W phase and the O phase are separated into two phases. A method for producing a spherical metal oxide, comprising a step of heating the phase to 50 ° C. or higher and then separating and removing the O phase to recover the W phase. The separated O phase method according to claim 1 to be reused as a hydrophobic organic solvent and a surfactant for W / O emulsion in the manufacture of the spherical metal oxide.