JPH07216096A - Method for producing ultraviolet light-absorbing polymethyl silylsesquioxane powder - Google Patents

Abstract

PURPOSE:To obtain the subject powder excellent in free flowability, absorbing ultraviolet light and simultaneously permitting the penetration of visible light by reacting a polymethyl silsesquioxane powder having silanol groups on the surface thereof with a titanate ester and subsequently hydrolyzing and drying the product. CONSTITUTION:Polymethyl silsesquioxane powder having silanol groups on the surface thereof and having an average particle diameter of 0.1-30mum, preferably 1-10mum, is reacted with a titanate ester of the formula: Ti(OR)4 (R is a 1-8C alkyl) (e.g. tetraethyl titanate) in an organic solvent (e.g. methanol). The reactional product is hydrolyzed and subsequently dt'ied to obtain the objective powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite powder having a surface layer, and more specifically to a composite polymethylsilsesquioxy compound which has excellent free-flowing properties and absorbs ultraviolet rays while transmitting visible light. The present invention relates to a method for producing sun powder.

[0002]

2. Description of the Related Art Silicone resin powders composed of trifunctional silsesquioxane units such as polymethylsilsesquioxane are known (JP-A-54-72300 and JP-A-60-13813). Gazette). This fine powder is an insoluble and infusible resin having a dense three-dimensional network-like molecular skeleton, excellent free-flowing properties, and gloss, and is used as a raw material for makeup cosmetics. Sho 6
0-13813 and JP-A-61-194009.
Issue). A method for producing such a polyorganosilsesquioxane in a spherical shape and controlling a narrow particle size distribution has been found (Japanese Patent Laid-Open No. 63-77940), and such a spherical silicone resin is Especially, since the lubricity is excellent, the cosmetics containing the same are excellent in smoothness and elongation (Japanese Patent Laid-Open No. 63-297313).

On the other hand, in recent years, the influence of ultraviolet rays on the skin has come to be regarded as a problem, and along with this, cosmetics containing an ultraviolet shielding agent are becoming mainstream.

However, among the silicone resin powders containing the silsesquioxane unit, those having an aromatic group such as a phenyl group as an organic group show absorption in the ultraviolet region, but have absorption strength and absorption region. Both cases are not suitable for use as cosmetics. In addition, polymethylsilsesquioxane, which is particularly easy to obtain a powder having a true spherical shape and a narrow particle size distribution, has essentially no absorption in the ultraviolet region. Therefore, a powder having an ultraviolet shielding property such as titanium oxide or zinc oxide is used in combination with this polymethylsilsesquioxane powder. However, according to this method, the obtained cosmetics have problems that the smoothness and elongation are reduced and whitish is exhibited as compared with the case where the polymethylsilsesquioxane powder is simply used.

[0005]

An object of the present invention is to provide a method for obtaining a composite polymethylsilsesquioxane powder having a titanium oxide layer as a surface layer. Another object of the present invention is to allow the polymethylsilsesquioxane powder to transmit visible light while maintaining its free flowing property, which provides excellent smoothness and elongation when used as a cosmetic raw material. , And to provide a method of imparting the ability to absorb ultraviolet rays without exhibiting whitishness.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has made a titanate ester react with the surface of polymethylsilsesquioxane powder and then hydrolyzes it. The present invention has been completed by finding that by drying and forming a titanium oxide layer on the surface of the powder, remarkable light absorption can be imparted only to ultraviolet without impairing the free flowing property and shape of the powder. Came to do.

That is, the present invention provides (1) (A) a polymethylsilsesquioxane powder having an average particle size of 0.1 to 30 μm and having a silanol group on the surface, and (B) a general formula: Ti ( OR) ₄ (where R is 1 carbon atom)
(Representing an alkyl group of ~ 8) is reacted in an organic solvent (C); (2) the reaction product is hydrolyzed; (3) the obtained hydrolysis product is dried. The present invention also relates to a method for producing an ultraviolet-absorbing polymethylsilsesquioxane powder.

The polymethylsilsesquioxane powder of (A) used in the present invention is obtained by, for example, methyltrialkoxysilane such as methyltrimethoxysilane or methyltriethoxysilane or a partial hydrolysis-condensation product thereof.
Obtained by hydrolysis and condensation in an aqueous solution of ammonia or amines, the surface of which has a silanol group and an alkoxy group such as methoxy or ethoxy bonded to a silicon atom corresponding to the methyltrialkoxysilane used. However, excess water can be present during the synthesis to form only silanol groups on the surface. In the present invention, any polymethylsilsesquioxane powder described above can be used as long as silanol groups are present on the surface.

The particle size of the polymethylsilsesquioxane powder is selected from the range of 0.1 to 30 μm, preferably 1
10 to 10 μm. If the average particle size is less than 0.1 μm or, conversely, exceeds 30 μm, the smoothness and elongation when blended in a cosmetic composition is impaired, which is not preferable. Further, since the cosmetics are excellent in smoothness and elongation, those having a narrow particle size distribution in the above range are preferable, and those having a true spherical shape are more preferable.

The titanate ester of (B) used in the present invention is represented by Ti (OR) ₄ . As mentioned above, R is an alkyl group having 1 to 8 carbon atoms, and examples thereof include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl, which may be linear or branched. Typical examples of such titanate ester include tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetrahexyl titanate and tetra (2-ethylhexyl) titanate. It is preferable that R is an alkyl group having 2 to 6 carbon atoms, since it has an appropriate hydrolyzability, it is easy to handle, good reactivity is obtained, and the yield of titanium oxide is good.

The amount of the component (B) used is not particularly limited, but is 0.01 per 100 parts by weight of the component (A).
-30 parts by weight is preferable, and 0.1-10 parts by weight is more preferable. If the amount of the component (B) is less than 0.01 part by weight, a sufficient ultraviolet absorbing effect cannot be obtained, and conversely, if it is more than 30 parts by weight, a certain effect cannot be obtained, and agglomeration of powder particles is not achieved. Is likely to occur and absorption also occurs in the visible part, which is not preferable.

The organic solvent (C) used in the present invention is
Although not particularly limited, a solvent capable of dissolving a certain amount of water is preferable because it is easy to effectively use the water added in the hydrolysis step. Examples of the solvent include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, and tert-butanol; ethyl ether, dichloroethyl ether, isopropyl ether, ethylene glycol diethyl. Ethers such as ether, dioxane, furan, tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, methyl isobutyl ketone; methyl acetate, ethyl acetate, n-propyl acetate, Isopropyl acetate, acetic acid-n-
Esters such as butyl, isobutyl acetate, acetic acid-sec-butyl; ethylene glycol monomethyl ether,
Examples thereof include polyhydric alcohol derivatives such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, and diethylene glycol monomethyl ether.

The amount of the component (C) used is not particularly limited and depends on the particle size of the component (A) to be treated, but the dispersion of the component (C) in which the component (A) is dispersed is Since it shows good workability and fluidity,
It is preferably 50 parts by weight or more based on 100 parts by weight of the component (A). Although the upper limit is not limited in the same manner, it is preferably 1,000 parts by weight or less with respect to 100 parts by weight of the component (A) in terms of work efficiency.

In the method for producing the composite powder of the present invention, the polymethylsilsesquioxane powder of (A) is reacted with the titanic acid ester of (B) in the organic solvent of (C), and then hydrolyzed. , By drying. As a concrete procedure,
The reaction of the component (A) and the component (B), which is the first step of the production method of the present invention, can be carried out by any of the following. The component (A) is added to a solution obtained by dissolving the components (a) and (B) in the component (C) and dispersed by stirring or shaking to obtain a dispersion. (B) The component (B) is added to the dispersion obtained by dispersing the component (A) in the component (C), and the mixture is stirred or shaken.

In this step, a condensation reaction proceeds between the silanol group existing on the surface of the component (A) and the alkoxy group of the titanate ester, and the powder surface is formed by the reaction with the titanate ester. Covered with a surface layer having a Si—O—Ti bond.

At this stage, the powder may be separated and collected by a method such as sedimentation or centrifugation and dried, but water is added to the dispersion before separation and collection,
By hydrolyzing the titanic acid ester, it is possible to obtain a surface layer exhibiting stronger ultraviolet absorption. The amount of water added at this time is not particularly limited, but is preferably 1 to 5 mol per 1 mol of the alkoxy group of the component (B) used. By this hydrolysis reaction, the alkoxy group of the surface layer bonded to the titanium atom derived from the component (B) and the alkoxy group remaining bonded to the silicon atom in the component (A) are hydrolyzed to form a titanol group, respectively. And silanol groups. Some may be further condensed to form a titanoxane bond, a titanosiloxane bond or a siloxane bond.

The reaction of the above components (A) and (B),
In addition, both of the hydrolysis reactions proceed sufficiently quickly even at room temperature, but the reaction may be promoted by heating to the reflux temperature of the solvent.

After the hydrolysis step is completed, the powder is separated and collected by a method such as sedimentation separation or centrifugation. After separation and collection, a solvent, preferably an organic solvent in the range of the component (C), is washed to remove the residual titanate ester and its partial hydrolyzed condensate to obtain a powder. It is possible to prevent agglomeration of the bodies and mixing of foreign matters due to the hydrolyzate of the titanate ester. Examples of the method for washing the powder include a method in which the powder is added to a solvent, stirred or shaken, and then separated and collected by sedimentation separation, centrifugation, or the like. This washing step may be repeated multiple times.

In the next drying step, the organic solvent existing in the powder-containing system is removed, and the alkoxy group remaining in the surface layer is converted into water remaining in the system and / or water existing in the atmosphere. It is carried out in order to complete the formation of the titanium oxide layer by hydrolyzing with and forming a titanoxane bond by a condensation reaction. The drying temperature may be room temperature, but it is preferably heated to a temperature of 50 to 250 ° C. At that time, a powder stirring device such as a fluidized stirring tank may be used.

The composite powder obtained according to the present invention has excellent free-flowing property, but further polyorganohydrogensiloxanes such as polymethylhydrogensiloxane; or organosilazanes such as hexamethyldisilazane. By surface treatment using
It is possible to impart further excellent fluidity and hydrophobicity to the powder.

[0021]

The polymethylsilsesquioxane powder having a surface layer obtained by the present invention absorbs ultraviolet rays and transmits visible light, and has excellent fluidity and smooth feel. Therefore, when added to a cosmetic, it imparts an excellent UV-shielding effect to the cosmetic and also provides good smoothness and spreadability, while not making the cosmetic whitish. Therefore, the composite powder obtained by the present invention is used as a component of various cosmetics including those for preventing ultraviolet rays.

Further, the composite powder obtained according to the present invention can be blended with various plastics to provide slipperiness and anti-blocking effect, and improve weather resistance.

[0023]

EXAMPLES The present invention will be described in detail below with reference to examples. In these examples, parts represent parts by weight. The invention is not limited by these examples.

Example 1 100 parts of spherical polymethylsilsesquioxane powder having an average particle diameter of 4.5 μm and a true specific gravity of 1.32 was dispersed in 300 parts of isopropyl alcohol to prepare tetrabutyl titanate 5 parts.
Parts were added and stirred at reflux temperature for 2 hours. Then, 0.4 part of water was added, and the mixture was stirred at reflux temperature for 2 hours. Next, the powder was separated and collected using a centrifuge. To the collected powder, 300 parts of isopropyl alcohol was added, and after mixing for 5 minutes using a shaker, the powder was centrifuged to wash the powder. After repeating this washing twice, the powder was dried in a dryer at 150 ° C. for 3 hours to obtain a free-flowing white powder.

Observation of a micrograph of this powder revealed that
It had the same spherical shape as that before the treatment. In addition, this powder was added to dimethyl silicone oil with a viscosity of 1,000 cSt at a concentration of 0.5.
%, And the light absorption was observed by a spectrophotometer. As a result, remarkable absorption was observed in the ultraviolet region of a wavelength of 400 nm or less. On the other hand, in the visible light range,
Absorption was slightly recognized in the region of 500 nm or less, but 5
In the region exceeding 00 nm, almost no absorption was observed. In addition, in the same observation of the powder before treatment, 300 to
No absorption was observed in the entire region of 750 nm.

Table 1 shows the appearance of the powder before and after the treatment (observation with a microscope) and the measurement results of the absorbance at 300 to 700 nm. The results of light absorption measurement after the treatment and before the treatment are shown in FIGS. 1 and 2, respectively.

[0027]

[Table 1]

Example 2 100 parts of a spherical polymethylsilsesquioxane powder having an average particle diameter of 1.8 μm and a true specific gravity of 1.32 was dispersed in 500 parts of acetone, and 10 parts by weight of tetrabutyl titanate was added. , Stirred at reflux temperature for 4 hours. Then, 1 part of water was added, and the mixture was stirred at reflux temperature for 4 hours. Next, the powder was separated and collected using a centrifuge. Acetone 50 on the collected powder
After adding 0 part and mixing for 5 minutes using a shaker, the powder was centrifuged to wash the powder. After repeating this washing twice, the powder was dried in a dryer at 150 ° C. for 2 hours to obtain a free-flowing white powder.

Observation of a micrograph of this powder revealed that
It had the same spherical shape as that before the treatment. In addition, this powder was added to dimethyl silicone oil with a viscosity of 1,000 cSt at a concentration of 0.5.
%, And light absorption was observed in the same manner as in Example 1. As a result, remarkable absorption was observed only in the ultraviolet region. In the same observation of the powder before treatment, no absorption was observed in the same range as in Example 1. The results are shown in Table 2.

[0030]

[Table 2]

Example 3 100 parts of a true spherical polymethylsilsesquioxane powder having an average particle diameter of 5.2 μm and a true specific gravity of 1.32 was dispersed in 200 parts of tetrahydrofuran, and 2 parts of tetrabutyl titanate was added, Stir at reflux temperature for 3 hours. Then water 0.3
Parts were added, and the mixture was stirred at reflux temperature for 3 hours. Next, the powder was separated and collected using a centrifuge. Tetrahydrofuran (200 parts) was added to the collected powder, the mixture was mixed for 5 minutes using a shaker, and then the powder was centrifuged to wash the powder. After repeating this washing twice, the powder was dried in a dryer at 150 ° C. for 2 hours to obtain a free-flowing white powder.

Observation of a micrograph of this powder revealed that
It had the same spherical shape as that before the treatment. In addition, this powder was added to dimethyl silicone oil with a viscosity of 1,000 cSt at a concentration of 0.5.
%, And light absorption was observed in the same manner as in Example 1. As a result, remarkable absorption was observed only in the ultraviolet region. In the same observation of the powder before treatment, no absorption was observed in the same range as in Example 1. The results are shown in Table 3.

[0033]

[Table 3]

[Brief description of drawings]

FIG. 1 is an absorbance-wavelength curve of polymethylsilsesquioxane of Example 1 having a surface layer formed by the production method of the present invention.

FIG. 2 is an absorbance-wavelength curve of polymethylsilsesquioxane before treatment.

Claims (1)

[Claims] (1) (A) The average particle size is 0.1 to 30 μm.
The polymethylsilsesquioxane powder of m having a silanol group on the surface is represented by (B) general formula: Ti (OR) ₄ (wherein R represents an alkyl group having 1 to 8 carbon atoms). (C) reacting titanic acid ester in an organic solvent; (2) hydrolyzing a reaction product; (3) drying the obtained hydrolysis product; Method for producing sesquioxane powder.