JP2007051188A - Low smell alkylsilylated powder, method for producing the same, silicone oil slurry dispersed with the low smell alkylsilylated powder, and cosmetic mixed with the low smell alkylsilylated powder or the silicone oil slurry - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alkylsilylated powder which is modified so as not to produce an unpleasant smell when mixed with cosmetics and by which a silicone oil slurry can be easily prepared. <P>SOLUTION: The low smell alkylsilylated powder is obtained by mixing metal oxide particles having an average primary particle size of 1 nm to 100 μm with an alkylalkoxysilane having at least one 1-20C alkyl group and at least one alkoxy group in a lower alcohol, adding 5-10 times by mass of water based on the alkylalkoxysilane at a temperature of 1-100°C to hydrolyze the alkylalkoxysilane, and heating and evaporating the lower alcohol and water to coat the surface of the metal oxide particles with an alkylsilane having at least one 1-20C alkyl group in an amount of 1-30 mass% based on the metal oxide particles. The low smell alkylsilylated powder is dispersed in a silicone oil to prepare the silicone oil slurry. Cosmetics are obtained by mixing the powder or the slurry. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes a low-odor alkylsilylation-treated powder, a production method thereof, a silicone oil slurry in which the low-odor alkylsilylation-treated powder is dispersed, and the low-odor alkylsilylation-treated powder or the silicone oil slurry. Related to cosmetics.

  Metal oxide particles such as titanium dioxide, zinc oxide, cerium oxide, zirconium oxide, and iron oxide have excellent ultraviolet shielding ability, and are therefore incorporated in many cosmetics including sunscreen cosmetics. When blending, various inorganic substances and organic substances are blended at the same time or surface treatment is performed to improve dispersibility.

  However, since the metal oxide particles have a large specific gravity, it is difficult to disperse them stably. For this reason, it has been proposed to improve dispersibility by coating the surface with an organic substance. Particularly recently, the main medium of cosmetics is a silicone compound, and it has been proposed to treat the surface of metal oxide particles with a silane compound for the purpose of improving the dispersibility in those mediums. The treated powder, so-called alkylsilylated powder, is reported to have excellent water resistance, good stability over time, and excellent pigment redispersibility when blended in cosmetics (patent) Reference 1).

  However, the alkylsilylation-treated powder has a unique unpleasant odor that is considered to be derived from the alkylsilane compound, and particularly when treated with a large amount of the alkylsilane compound for the purpose of improving the characteristics, the unpleasant odor is reduced. For this reason, there is a problem that the quality of the cosmetic is lowered.

  That is, the alkylsilylation treatment of metal oxide particles is generally performed by using alkylalkoxysilane as a treating agent and forming a film of alkylsilane on the surface of the metal oxide particles using hydrolysis of alkylalkoxysilane. Has been done.

  Specifically, an alkylalkoxysilane aqueous solution or a mixed solution of an alkylalkoxysilane, water, and a lower alcohol is prepared, and metal oxide particles are added and mixed to form a slurry. Is hydrolyzed, and then the liquid components are separated and dried. Hydrolysis of alkylalkoxysilanes by this method proceeds in the presence of water, but dehydration condensation reaction between silanol groups generated by hydrolysis of alkylalkoxysilanes and hydroxyl groups present on the surface of metal oxide particles. Occurs, the surface treatment is performed, whereby the metal oxide particle surface is coated with alkylsilane. However, since the silanol group generated in the liquid is highly reactive, a siloxane polymer insoluble in water is formed before reacting with the hydroxyl group on the particle surface of the metal oxide, and the formed siloxane polymer is a metal oxide. A compound containing an alkyl alkoxysilane that is not decomposed (unhydrolyzed) when the siloxane polymer is formed because it does not contribute to the surface treatment of the particles and thus does not contribute to the improvement of the surface characteristics of the metal oxide particles. And undecomposed alkylalkoxysilane or the like remains in the metal oxide after the surface treatment to generate an unpleasant odor.

  In order to solve the problem of generating the unpleasant odor, a method of making the pH weakly acidic by adding acetic acid or the like may be employed. As a result, the hydrolyzability of the alkylalkoxysilane can be increased and the stability of the silanol group can be improved, so that the production of the siloxane polymer can be delayed. However, this method has a problem that the hydrolysis rate of the alkylalkoxysilane becomes too fast, making it difficult to uniformly treat the surface of the metal oxide particles, and the problem that the acetic acid odor tends to remain. there were.

  Furthermore, a method has also been proposed in which metal oxide particles are introduced into a mixer or blender, and alkylalkoxysilane or a solution thereof is sprayed onto the metal oxide while stirring or grinding. However, this method also has the same problem as the treatment performed in the liquid system described above, that is, the problem that an unpleasant odor derived from the alkylalkoxysilane odor occurs, and the problem that the surface treatment becomes uneven. .

JP 2000-264824 A

  The present invention solves the problems related to the alkylsilylation-treated powder as described above, and is a low-brominated alkylsilylation-treated powder that does not cause an unpleasant odor when blended in cosmetics, its production method, It is an object of the present invention to provide a cosmetic material free from an unpleasant odor by blending a silicone oil slurry in which an odor alkylsilylation-treated powder is dispersed in a high concentration and the alkylsilylation-treated powder or the silicone oil slurry.

  The first gist of the present invention is that the surface of metal oxide particles having an average primary particle diameter of 1 nm to 100 μm is coated with an alkylsilane having at least one alkyl group having 1 to 20 carbon atoms. Low odor alkylsilylated powder characterized in that the coating amount is 1 to 30% by mass with respect to the metal oxide particles (1 to 30 parts by mass of alkylsilane with respect to 100 parts by mass of metal oxide particles). It is about.

  The metal oxide in the low odor alkylsilylated powder is preferably at least one selected from the group consisting of titanium dioxide, zinc oxide, cerium oxide, zirconium oxide and iron oxide, and the average primary of the metal oxide particles The particle diameter is preferably 5 nm to 100 nm, the coating amount of the alkylsilane is preferably 10 to 20% by mass with respect to the metal oxide particles, and the alkyl group of the alkylsilane has 6 to 15 carbon atoms. Preferably, the metal oxide particles have a surface treated beforehand with at least one selected from the group consisting of Si, Al, Ti, Zr hydroxides or oxides. May be.

  The second gist of the present invention is to provide a metal oxide particle having an average primary particle diameter of 1 nm to 100 μm and an alkylalkoxysilane having at least one alkyl group having 1 to 20 carbon atoms and at least one alkoxy group. Mixing in alcohol, adding 5 to 10 times the mass of water to the alkylalkoxysilane at a temperature of 1 to 100 ° C. to hydrolyze the alkylalkoxysilane, and then distilling off the lower alcohol and water by heating. A low odor alkylsilylation characterized in that the metal oxide particles are coated with 1 to 30% by mass of alkylsilane having at least one alkyl group having 1 to 20 carbon atoms on the surface of the metal oxide particles. The present invention relates to a method for producing a treated powder.

  In the production of the low odor alkylsilylation-treated powder, the addition time of water added to the reaction system is preferably 30 to 180 minutes in total. The metal oxide used in the production of the alkylsilylated powder is preferably at least one selected from the group consisting of titanium dioxide, zinc oxide, cerium oxide, zirconium oxide and iron oxide. The primary particle diameter is preferably 5 nm to 100 nm, and the coating amount of the alkylsilane compound is preferably 10 to 20% by mass with respect to the metal oxide particles of the alkylsilane, the alkylalkoxysilane or the alkylsilane. Preferably, the alkyl group has 6 to 15 carbon atoms, and the metal oxide particles are Because, the surface Si, Al, Ti, or may be treated with at least one member selected from the group consisting of hydroxides or oxides of Zr.

  The third gist of the present invention relates to a silicone oil slurry characterized in that the low-odor alkylsilylated powder is dispersed in silicone oil, and the low-odor alkylsilyl in the silicone oil slurry The dispersion amount of the chemical treatment powder is preferably 30 to 70% by mass.

  The fourth gist of the present invention relates to a cosmetic comprising the low odor alkylsilylated powder or the silicone oil slurry.

  The low odor alkylsilylation-treated powder of the present invention has excellent dispersibility due to the coating with metal silane on the surface of metal oxide particles, and is more alkylsilane than conventional alkylsilylation-treated powder. There are few unpleasant odors derived from compounds.

  In addition, the low odor alkyl silylation-treated powder of the present invention has excellent dispersibility due to the coating of metal oxide particles on the surface with alkyl silane. A silicone oil slurry dispersed in oil at a high concentration can be prepared, thereby making it easier to handle in preparing cosmetics and the like.

  Furthermore, the low odor alkylsilylated powder of the present invention is excellent in dispersibility by coating the surface of the metal oxide particles with alkylsilane as described above, and has less unpleasant odor derived from alkylalkoxysilane. Therefore, a cosmetic without an unpleasant odor can be prepared. Moreover, if the above-mentioned silicone oil slurry is used, a cosmetic without an unpleasant odor can be more easily prepared.

  The low odor alkylsilylation-treated powder of the present invention has less unpleasant odor derived from alkylalkoxysilane because a specific amount of water is specified during hydrolysis of alkylalkoxysilane during surface treatment of metal oxide particles. Since it is added over time, a uniform coating of alkylsilane is formed on the surface of the resulting powder, and it does not contribute to residual unreacted substances, which are considered to be the main cause of unpleasant odors, and characteristics after surface treatment. This is considered to be due to the fact that both the formation of the siloxane polymer could be suppressed.

  In addition, in the surface treatment for metal oxide particles, when uniform treatment, that is, uniform film formation is performed, the viscosity in the case of using a silicone oil slurry is lower than in the case where it is not. Since the alkylsilylation-treated powder of the present invention has a lower viscosity when a silicone oil slurry is prepared than the conventional alkylsilylation-treated powder, the alkylsilylation-treated powder of the present invention is 30% by mass or more. A silicone oil slurry dispersed at a high concentration can be prepared.

  In the alkylsilylation-treated powder of the present invention, the base material is metal oxide particles having an average primary particle diameter of 1 nm to 100 μm. Examples of the metal oxide include titanium dioxide, zinc oxide, and cerium oxide. Zirconium oxide, iron oxide and the like are preferably used. These metal oxides are generally used as coloring agents, ultraviolet shielding agents, and infrared shielding agents in cosmetic applications. In the present invention, these metal oxides are used as base materials for alkylsilylated powders. As for the product particles, those having an average primary particle size of 1 nm to 100 μm are used. When the average primary particle size is smaller than 1 nm, the cohesive force between the particles becomes very strong, and the surface treatment is uniform on each particle. However, even if the base material becomes large, no particular problem will occur. However, as a compounding agent for cosmetics, those having an average primary particle size of up to about 100 μm are suitable for practical use. It is. And when the average primary particle diameter of the metal oxide particles of the substrate is 5 nm or more, the surface treatment becomes easier to perform, and those having an average primary particle diameter of 0.1 μm (100 nm) or less have an ultraviolet shielding effect. Since it is excellent, as a metal oxide particle of a base material, a thing with an average primary particle diameter of 5 nm-100 nm is preferable. In the present invention, the average primary particle diameter of the metal oxide particles used as the base material is obtained by photographing the metal oxide particles with a transmission electron microscope (the number of photographs is 1,000 or more, respectively) This is obtained by plotting the unidirectional diameter of each particle (the length of the horizontal line that bisects the particle area) and averaging them.

  The crystal form of the metal oxide serving as the base material is not particularly limited. For example, in the case of titanium dioxide, any of rutile, anatase, brookite, and amorphous forms may be used. The shape may be any of spherical, rod-like, spindle-like, needle-like, plate-like, and indefinite shape. Further, before the alkylsilylation treatment on the surface of these metal oxide particles, in order to impart light resistance, chemical resistance, etc., a hydroxide or oxide of Si, Al, Ti, Zr in advance. You may surface-treat with at least 1 sort.

  In the present invention, the alkylalkoxysilane used for the surface treatment on the metal oxide particles has at least one alkyl group having 1 to 20 carbon atoms and at least one alkoxy group. Those of formulas 6 to 15 are preferable, and this alkyl group may be not only one but also two or more. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a butoxy group. The number of alkoxy groups is not limited to one, and may be two or more. In the present invention, the alkyl group in the alkylalkoxysilane is particularly preferably an octyl group, the alkoxy group is particularly preferably an ethoxy group, and therefore the alkylalkoxysilane is preferably octylethoxysilane, particularly octyltriethoxysilane.

  In the present invention, the surface treatment of the metal oxide particles with the alkylalkoxysilane will be described in detail later, but the metal oxide particles and the alkylalkoxysilane are mixed in a lower alcohol to obtain a specific amount of water. Is added to hydrolyze the alkylalkoxysilane, and the surface of the metal oxide particles is coated with the alkylsilane. 1 to 30% by mass (as described above, the coating amount of the alkyl silane with respect to the metal oxide particles is 1 to 30% by mass with respect to the metal oxide particles. It means that it is 1 to 30 parts by mass of silane), preferably 10% by mass or more, and more preferably 20% by mass or less. It is preferred.

  When the coating amount of the alkyl silane on the metal oxide particles is less than 1% by mass, the surface coating effect by the alkyl silane is not sufficiently exhibited, and therefore the dispersibility is not sufficiently improved. Further, when the coating amount of the alkyl silane on the metal oxide particles is more than 30% by mass, the amount of the metal oxide is relatively decreased, and the ultraviolet shielding ability, which is the original function of the metal oxide, is sufficient. Cannot be demonstrated.

  In the present invention, the coating treatment of the metal oxide particle surface with the alkyl silane is carried out by mixing the metal oxide particles and the alkyl alkoxy silane in the lower alcohol. The lower alcohol is used because the lower alcohol is useful as a medium in which the alkylalkoxysilane is dissolved and the metal oxide particles are dispersed, and is easily removed from the system by distillation. The lower alcohol is preferably an alcohol having 4 or less carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, tertiary butyl alcohol and the like. Above all, Isopro Alcohol (IPA) is particularly preferred.

And, the outline of the process of passing through to obtain the low odor alkylsilylation-treated powder of the present invention, that is, the process of the surface treatment with the alkylalkoxysilane to the metal oxide particles is as follows, for example. .
(1) An alkylalkoxysilane having at least one alkyl group having 1 to 20 carbon atoms and at least one alkoxy group is introduced into a lower alcohol such as IPA at a ratio of 1 to 30% by mass based on the metal oxide. Then, metal oxide particles are added thereto, mixed and slurried.

  At this time, a dispersion process using a sand grinder mill or the like for the purpose of performing a uniform surface treatment for each metal oxide particle by making the mixing more dense and reducing the aggregation of the metal oxide particles May be added.

(2) While stirring the slurry, water of 5 to 10 times weight with respect to the alkylalkoxysilane is gradually added at a temperature of 1 to 100 ° C., preferably over 30 to 180 minutes. Silane is hydrolyzed. The silanol group produced by hydrolysis of the alkylalkoxysilane causes a dehydration condensation reaction with the hydroxyl group present on the surface of the metal oxide particle, forming a film of alkylsilane on the surface of the metal oxide particle, Thereby, the surface of the metal oxide particles is coated with alkylsilane.

  In the present invention, in the production of the low odor alkylsilylation-treated powder, the amount of water to be added is 5 to 10 times that of the alkylalkoxysilane. When the amount is small, undecomposed (unhydrolyzed) alkylalkoxysilane remains, which is likely to cause unpleasant odors. When the amount of water added is more than the above range, the distillation energy is reduced in the subsequent distillation step. Is excessively necessary, uneconomical and unpreferable. The amount of water added is preferably 6.5 times or more, and 8.5 times or less that of alkylalkoxysilane. .

  The temperature during the reaction is not particularly limited, and a wide temperature range of 1 to 100 ° C. can be adopted. In particular, 20 ° C. or higher is preferable, and 60 ° C. or lower is preferable.

  The total addition time of water to the reaction system is preferably 30 minutes to 180 minutes, for the following reason. That is, when the addition time of water is shorter than 30 minutes, that is, when the addition rate of water is too high, the hydrolysis reaction of the alkylalkoxysilane proceeds rapidly, and a siloxane polymer insoluble in water is generated in the system. Therefore, it is difficult to form a uniform alkylsilane coating on the surface of the metal oxide particles, and when the siloxane polymer is formed, undegraded (unhydrolyzed) alkylalkoxysilanes or unhydrolyzed This is because an unpleasant odor derived from the alkylalkoxysilane may be left in the alkylsilylated powder as a result of incorporating reaction components and the like, and when the addition time of water is longer than 180 minutes, that is, addition This is because if the speed is too slow, uniform surface treatment can be performed, but the productivity is greatly reduced. The total addition time of the water is more preferably 60 minutes or more, and more preferably 90 minutes or less.

(3) After adding water, the slurry is transferred to a heating vacuum still, and lower alcohol and water are distilled off by heating. That is, it is removed by heating and evaporation.

(4) After removal by evaporation of lower alcohol and water, the temperature of the still is raised as it is, or the treated product is once taken out of the still and placed in a drier and cured (baked). The curing temperature is preferably 120 ° C. or higher from the viewpoint of efficient removal of residual alcohol, and 180 ° C. or lower is preferable from the viewpoint of preventing alkylsilane alteration.

(5) The treated product is pulverized, and the low-odor alkylsilylated powder, that is, the metal oxide particles as a base material, and the surface of the metal oxide particles as the base material is formed with a specific alkylsilane. A coated powder with less unpleasant odor is obtained. In the pulverization process, a known general pulverizer such as an EX atomizer or a fluid energy mill can be used. In the thus obtained low odor alkylsilylation-treated powder, the surface of the metal oxide particles is coated with a specific alkylsilane, and the alkylsilane is changed from the alkylalkoxysilane used for the surface treatment. However, since the mass change accompanying the change from alkylalkoxysilane to alkylsilane in the above production process is very small, the amount of alkylalkoxysilane used in the surface treatment is the amount of alkylsilane in the low odor alkylsilylated powder. What is necessary is just to use about the same as the coating amount.

  The low-odor alkylsilylated powder of the present invention obtained as described above is excellent in dispersibility because it is uniformly coated with alkylsilane, and is blended in the preparation of cosmetics. However, when the oily cosmetic is prepared, the low-odor alkylsilylated powder of the present invention is preliminarily prepared in the cosmetic. If it is dispersed in silicone oil to form a silicone oil slurry, it becomes easier to blend into cosmetics.

  Since the low-odor alkylsilylated powder of the present invention has excellent dispersibility as described above, the dispersibility is excellent in preparing this silicone oil slurry, and the silicone can be used without using a dispersant. Although an oil slurry can be prepared, a silicone oil slurry can be more easily prepared by using a small amount of a dispersant. For example, PEG-10 dimethicone (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6017P) can be used as a dispersant. Can be used to prepare a high-concentration silicone oil slurry in which the dispersion amount of the low-odor alkylsilylation-treated powder is 30% by mass or more. It is possible to add a large amount of low-odor alkylsilylated powder to a cosmetic. The dispersion amount of the low odor alkylsilylated powder in the silicone oil slurry can be up to about 70% by mass, and if it is up to about 60% by mass, the silicone oil slurry can be easily prepared. It can be carried out.

  The silicone oil slurry of the low odor alkylsilylated powder of the present invention has a lower viscosity than the conventional silicone oil slurry in which the alkylsilylated powder is dispersed in silicone oil. The viscosity of a silicone oil slurry having a composition of 40% by mass of silylated powder, 55% by mass of decamethylcyclopentasiloxane as a silicone oil, and 5% by mass of PEG-10 dimethicone (supra) as a dispersant is The viscosity measured under the conditions of 25 ° C. and 60 rpm using a B-type viscometer is 5000 mPa · s or less. By the way, the viscosity of the silicone oil slurry having the same composition as above was used in place of the low odor alkylsilylated powder of the present invention, except that a conventional alkylsilylated powder was used. The viscosity measured under the same conditions as above is 10,000 mPa · s or more.

  The low odor alkylsilylated powder of the present invention can be blended in various cosmetics. For example, when blended in cosmetics such as sunscreen agents (sunscreen agents), makeup bases, foundations, etc., The ultraviolet shielding effect can be further improved as compared with the case of blending the alkylsilylated powder. This is based on the low odor alkylsilylation-treated powder of the present invention having good dispersibility.

  When the low odor alkylsilylation-treated powder of the present invention is blended in a cosmetic, the blending amount is preferably 0.5 to 30% by mass in the entire cosmetic. When the blend amount of the low odor alkylsilylation-treated powder of the present invention is less than 0.5% by mass, the ultraviolet shielding effect may not be sufficiently exhibited, and the low-odor alkylsilylation-treated powder of the present invention This is because even if the blending amount of the body is more than 30% by mass, there is no increase in the effect and the economic loss increases. Further, when blended into a cosmetic as a silicone oil slurry, the low-odor alkylsilylated powder of the present invention may be 0.5 to 30% by mass in the entire cosmetic as described above. preferable.

  The low odor alkylsilylation-treated powder of the present invention is intended for a metal oxide particle as a base material and the surface thereof is coated with a specific alkylsilane. The method can also be applied to those using a base material other than metal oxide particles. For example, dyes, lake dyes, polymer powders, inorganic pigments, extender pigments, pearl pigments, metal salt powders, etc. are used as base materials, and alkyl silane coatings are formed on the particle surfaces using alkyl alkoxy silane as a treatment agent. Thus, the present invention can also be applied to the case where the particle surface is coated with alkylsilane.

  Next, the present invention will be described more specifically with reference to examples. However, this invention is not limited only to those Examples.

Example 1
To 2500 g of IPA, 440 g of octyltriethoxysilane (Nihon Unicar Co., Ltd., A-137) was added and mixed well. To this was added 2500 g of hydrous silicic acid / aluminum hydroxide-treated fine particle titanium oxide (manufactured by Teika Co., Ltd., MT-05) having an average primary particle diameter of 10 nm, mixed and slurried. The obtained slurry was subjected to a dispersion treatment using a horizontal continuous sand grinder mill (manufactured by Willy et Bacco-fen, Dyno Mill). The residence time of the slurry in the mill was 5 minutes to sufficiently disperse the fine particle titanium oxide.

  The slurry after the dispersion treatment was put into a kneader having a vacuum distillation function and stirred. To this, 3000 g of water was added over 60 minutes to hydrolyze octyltriethoxysilane so that a dehydration condensation reaction occurred between the generated silanol groups and the hydroxyl groups present on the particle surfaces of the fine particle titanium oxide. . The water addition rate was 50 ml / min. Thereafter, heating under reduced pressure was performed to remove the solvent (IPA and water) by evaporation, and further curing was performed at 120 to 150 ° C. for 4 hours. The treated product is taken out from the kneader, pulverized with an ectomizer, and the surface of the octyl silylation-treated powder based on fine particle titanium oxide, that is, the hydrous silicic acid / aluminum hydroxide treated fine particle titanium oxide with octylsilane. A coated low odor alkylsilylated powder was obtained. The coating amount of octylsilane in this low-odor alkylsilylated powder was 17.6% by mass relative to the hydrous silicic acid / aluminum hydroxide-treated fine particle titanium oxide of the base material.

Example 2
In the same manner as in Example 1, 410 g of octyltriethoxysilane was added to 6000 g of IPA and mixed well. To this, 3000 g of fine particle zinc oxide having an average primary particle size of 25 nm (Taika Co., Ltd., MZ-500) was added, mixed and slurried. The obtained slurry was dispersed using a horizontal continuous sand grinder mill. The residence time of the slurry in the mill was 5 minutes to sufficiently disperse the fine zinc oxide.

  The slurry after the dispersion treatment was put into a kneader having a vacuum distillation function and stirred. To this, 3000 g of water was added over 100 minutes to hydrolyze the octyltriethoxysilane so that a dehydration condensation reaction occurred between the generated silanol group and the hydroxyl group on the particle surface of the fine zinc oxide. The water addition rate was 30 ml / min. Thereafter, heating under reduced pressure was performed to remove the solvent (IPA and water) by evaporation, and further curing was performed at 120 to 150 ° C. for 4 hours. The processed product is taken out from the kneader, pulverized with an ectomizer, and octyl silylation powder based on fine zinc oxide, that is, low odor alkyl silylation treatment with fine zinc oxide particles coated with octylsilane. A powder was obtained. The coating amount of octylsilane in this low-odor alkylsilylated powder was 13.7% by mass with respect to fine zinc oxide.

Comparative Example 1
The same treatment as in Example 1 was performed except that the water addition time in Example 1 was changed to 15 minutes. The addition rate of water in Comparative Example 1 was 200 ml / min.

Comparative Example 2
440 g of octyltriethoxysilane was added to 2500 g of IPA and mixed well. To this, 2500 g of hydrous silicic acid / aluminum hydroxide treated fine particle titanium oxide (manufactured by Teika Co., Ltd., MT-05) having an average primary particle size of 10 nm and 3000 g of water were added and mixed to form a slurry. The obtained slurry was dispersed using a horizontal continuous sand grinder mill. The residence time of the slurry in the mill was 5 minutes.

  The slurry after the dispersion treatment was put into a kneader having a vacuum distillation function and stirred. Thereafter, the mixture was evaporated and heated under reduced pressure to evaporate and remove the solvent (IPA and water), and further cured at 120 to 150 ° C. for 4 hours. The treated product was taken out from the kneader and pulverized with an ectomizer to obtain an octylsilylation-treated powder based on fine particle titanium oxide.

Comparative Example 3
410 g of octyltriethoxysilane was added to 500 g of IPA to prepare a mixed solution. To a Henschel mixer, 3000 g of fine particle zinc oxide (manufactured by Teika Co., Ltd., MZ-500) was charged, and the octyltriethoxysilane / IPA mixed solution prepared previously was sprayed there. The rotation speed of the Henschel mixer at this time was 500 rpm. After mixing for 10 minutes, the mixed powder was taken out, transferred to a dryer, and cured at 120 ° C. to 150 ° C. for 4 hours. The treated product was taken out from the dryer and pulverized with an ectomizer to obtain an octylsilylation treated powder based on fine zinc oxide.

Test example:
Surface treatment uniformity and odor confirmation test:
A low-concentration alkylsilylated powder obtained in Examples 1 and 2 and a high-concentration silicone oil slurry of the alkylsilylated powder obtained in Comparative Examples 1 to 3 were prepared. A sensory test on the viscosity and odor of was carried out. Thus, in the confirmation test of the uniformity and odor of the surface treatment, a high concentration silicone oil slurry was prepared, and the test was performed to detect the characteristic odor emitted from the alkylsilylated powder. In the case of using a high-concentration silicone oil slurry, if the odor strength can be determined more clearly and the surface treatment on the powder is more uniform, the slurry viscosity is relatively low. This is because the difference becomes clearer when the concentration is high.

  Specifically, the low-odor alkylsilylation-treated powders of Examples 1 and 2 and the alkylsilylation-treated powders of Comparative Examples 1 to 3 were each 3000 g and decamethylcyclopentasiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., KF). -995) 4125 g and 375 g of PEG-10 dimethicone (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6017P) were mixed with each other and passed through one pass with a dyno mill to obtain a slurry.

About each obtained high concentration silicone oil slurry, the measurement of a viscosity and the sensory test with respect to an odor were performed immediately after preparation and after storing for 30 days at room temperature (25 degreeC). The measurement or evaluation method is as follows.
viscosity:
Using a B-type viscometer [manufactured by BROOKFIELD, DIGITAL VISCOMETER MODEL DV-1 +], the viscosity of each slurry was measured under the conditions of 25 ° C. and 60 rpm. The results are shown in Table 1.

Odor (sensory evaluation):
Ten panelists were allowed to smell each of the slurries and evaluated their odor level. In other words, the evaluation was made according to the evaluations of “almost no smell”, “slightly smell”, “slightly smell”, and “strongly smell”. The results are shown in Table 1. In this case, the evaluation result with the largest number of people was displayed.

  In addition, as one of the evaluation items related to odor, the concentration of gas generated from each alkylsilylated powder under certain conditions was measured as follows. The results are also shown in Table 1.

Gas concentration measurement:
0.5 g of an object to be measured was placed in an odor bag with a capacity of 3 liters inflated with air, and was allowed to stand at 25 ° C. for 24 hours in a dark place. Then, the gas concentration was measured with a multi-gas monitor and a gas detection tube. The multi-gas monitor used for the measurement is a 1312 type acoustic gas monitor manufactured by INNOVA, and the temperature / humidity conditions at the time of measurement are room temperature 25-28 ° C./humidity 23-25%. The gas concentration measurement results are shown in Table 1 together with the viscosity measurement results and the odor sensory evaluation results of the high-concentration silicone oil slurry.

  As is clear from the results shown in Table 1, the low odor alkylsilylated powders of Examples 1 and 2 are evaluated as having almost no odor in the sensory test of odor, that is, having almost no unpleasant odor, Compared with the alkylsilylation-treated powders of Comparative Examples 1 to 3, the amount of gas released was small. In addition, the low-odor alkylsilylation-treated powders of Examples 1 and 2 have a lower slurry viscosity than the alkylsilylation-treated powders of Comparative Examples 1 to 3, and the surface treatment with alkylsilane is uniformly performed. It showed that. Furthermore, the low-odor alkylsilylation-treated powders of Examples 1 and 2 had little increase in gas concentration and slurry viscosity after 30 days.

Claims (16)

The surface of the metal oxide particles having an average primary particle diameter of 1 nm to 100 μm is coated with an alkylsilane having at least one alkyl group having 1 to 20 carbon atoms, and the coating amount of the alkylsilane is on the metal oxide particles. A low-odor alkylsilylated powder characterized by being 1 to 30% by mass. The low-odor alkylsilylated powder according to claim 1, wherein the metal oxide is at least one selected from the group consisting of titanium dioxide, zinc oxide, cerium oxide, zirconium oxide and iron oxide. The low odor alkylsilylation-treated powder according to claim 1 or 2, wherein the metal oxide particles have an average primary particle diameter of 5 nm to 100 nm. The metal oxide particles are obtained by previously treating the surface with at least one selected from the group consisting of hydroxides or oxides of Si, Al, Ti, and Zr. Low odor alkylsilylated powder. The low odor alkylsilylation-treated powder according to any one of claims 1 to 4, wherein the coating amount of the alkylsilane is 10 to 20 mass% with respect to the metal oxide. The low-odor alkylsilylated powder according to any one of claims 1 to 5, wherein the alkyl group has 6 to 15 carbon atoms. A metal oxide particle having an average primary particle diameter of 1 nm to 100 μm and an alkylalkoxysilane having at least one alkyl group having 1 to 20 carbon atoms and at least one alkoxy group are mixed in a lower alcohol, and the alkylalkoxysilane is mixed. 5 to 10 times the mass of water is added at a temperature of 1 to 100 ° C. to hydrolyze the alkylalkoxysilane, and then the lower alcohol and water are distilled off by heating to obtain the surface of the metal oxide particles. A method for producing a low-odor alkylsilylated powder, which comprises coating 1 to 30% by mass of at least one alkylsilane having 1 to 20 carbon atoms with respect to the metal oxide particles. The method for producing a low odor alkylsilylated powder according to claim 7, wherein the metal oxide is at least one selected from the group consisting of titanium dioxide, zinc oxide, cerium oxide, zirconium oxide and iron oxide. The method for producing a low-odor alkylsilylated powder according to claim 7 or 8, wherein the average primary particle diameter of the metal oxide particles is 5 nm to 100 nm. The metal oxide particles are obtained by previously treating the surface with at least one selected from the group consisting of hydroxides or oxides of Si, Al, Ti, and Zr. For producing low-odor alkylsilylation-treated powder. The method for producing a low-odor alkylsilylated powder according to any one of claims 7 to 10, wherein the alkyl group has 6 to 15 carbon atoms. The method for producing a low-odor alkylsilylated powder according to any one of claims 7 to 11, wherein the total addition time of water is 30 to 180 minutes. A silicone oil slurry, wherein the low odor alkylsilylated powder according to any one of claims 1 to 6 is dispersed in silicone oil. The silicone oil slurry according to claim 13, wherein the dispersion amount of the low odor alkylsilylated powder in the silicone oil slurry is 30 to 70 mass%. A cosmetic comprising the low-odor alkylsilylated powder according to any one of claims 1 to 6. A cosmetic comprising the silicone oil slurry according to claim 13 or 14.