JP2018115098A - Surface treated zinc oxide powder and usage thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide surface treated zinc oxide powder, which can give dispersion having high dispersibility to an organic solvent, small particle diameter, and low viscosity, and also dispersion and cosmetics which uses this surface treated zinc oxide powder.SOLUTION: Surface treated zinc oxide powder including no aluminum element, surface of which has been treated with N-acyl amino acid salt and which has ratio of A/B of within a range of 0.60 to 1.20, where A is a maximum peak strength in a range from 2895 to 2953 cm, and B is a maximum peak strength in a range from 870 to 886 cmwhen the powder is undergoes infrared spectroscopy.SELECTED DRAWING: None

Description

The present invention relates to a surface-treated zinc oxide powder and use thereof. More specifically, the present invention relates to a surface-treated zinc oxide powder, a dispersion using the same, and a cosmetic.

Zinc oxide is also called zinc white. For example, nano-sized fine zinc oxide is widely used in various applications such as cosmetics, paints, plastics, etc. due to its UV shielding effect and visible light transparency. . Zinc oxide is often surface-treated for the purpose of improving compatibility with other compounding materials, and silicone treatment is often applied for cosmetic applications (see, for example, Patent Document 1). It has also been proposed to perform amino acid treatment other than silicone (see, for example, Patent Documents 2 and 3). In addition, since the fine zinc oxide is nano-sized and has a strong cohesive force between particles, it is generally dispersed in a liquid dispersion medium by a bead mill or the like before blending.

JP 2003-95655 A Japanese Patent Publication No. 1-50202 JP-A-3-200909

As mentioned above, zinc oxide is often subjected to silicone treatment, but since silicone treatment gives strong water repellency, there is a problem that it is difficult to remove with soap or the like after use. On the other hand, amino acid treatment has good adhesion to the skin and is relatively easy to clean. However, as the inventors of the present invention intensively studied, zinc oxide subjected to conventional amino acid treatment has a high viscosity and cannot be dispersed in an organic solvent in a liquid state, or even when a dispersion is obtained, It has been found that the viscosity is increased and the particles are aggregated, resulting in an increase in particle size. Aggregation of particles increases the risk that the finish when the cosmetic is applied to the skin, for example, when the dispersion is used as a raw material for cosmetics, may become unexpectedly white or feel worse. There was a problem in the point.

In view of the above situation, an object of the present invention is to provide a surface-treated zinc oxide powder that has a high dispersibility in an organic solvent and can provide a dispersion having a fine particle size and a low viscosity. Another object of the present invention is to provide a dispersion and a cosmetic using the surface-treated zinc oxide powder.

As described above, the inventors of the present invention have repeatedly studied the surface treatment of zinc oxide, and if the surface is made of zinc oxide powder treated with an N-acylated amino acid salt, the feel is good and high water repellency is obtained. Although I thought, even if the N-acylated amino acid salt was surface-treated by a usual method, it could not be dispersed in an organic solvent such as silicone oil, and a dispersion could not be obtained, or a low-viscosity dispersion was obtained. However, it has been found that there are many cases where the particle size becomes large and is not suitable for practical use. Therefore, as the investigation proceeds further, if the intensity ratio between the predetermined peaks by the infrared spectroscopy of the surface-treated zinc oxide powder is within a predetermined range, that is, specifically, the maximum peak at 2895 to 2953 cm ^−1. If the ratio (A / B) between the strength A and the maximum peak strength B at 870 to 886 cm ⁻¹ is in the range of 0.60 to 1.20, the dispersibility in an organic solvent such as silicone oil can be improved. It has been found that it is dramatically improved and gives a dispersion with a fine particle size and a low viscosity. However, even if this strength ratio is within this range, dispersibility in an organic solvent is reduced if an aluminum element is contained, such as zinc oxide powder coated with aluminum oxide often used as a surface treatment agent. It has also been found that the particle size and viscosity are remarkably increased when a dispersion is formed, and that this problem can be solved by using a surface-treated zinc oxide powder containing no aluminum element. In addition, the cosmetics using the surface-treated zinc oxide powder have been found to have a good feel without causing the finish to be white, and to be a highly water-repellent cosmetic that is resistant to sweat and water. I came up with a solution. In this way, the present invention has been completed.

That is, the present invention, the surface is treated with N- acylated amino acid salt, when measured by infrared spectroscopy, and strength A of the maximum peak at 2895～2953Cm ^-1, in 870～886Cm ^-1 The ratio of the maximum peak intensity B (A / B) is in the range of 0.60 to 1.20, and the surface-treated zinc oxide powder does not contain an aluminum element.

The average primary particle size of the powder is preferably 10 to 100 nm.
The N-acylated amino acid salt is preferably cocoyl glutamate.

The present invention is also a dispersion containing the surface-treated zinc oxide powder and an organic solvent, wherein the dispersion has a D90 in a particle size distribution of 1000 nm or less and a powder concentration of 40% by mass or more. It is also a dispersion.

The organic solvent preferably contains silicone oil.

The present invention is also a cosmetic containing the dispersion.

The surface-treated zinc oxide powder of the present invention has high dispersibility in an organic solvent, and can give a dispersion having a fine particle size and a low viscosity. Such a dispersion is particularly useful as a cosmetic raw material because it has a good feel when applied to the skin and can provide a highly water-repellent cosmetic material that is resistant to sweat and water. Moreover, the surface-treated zinc oxide powder of the present invention and a dispersion using the same are useful not only for cosmetics but also as raw materials for inks and paints.

Hereinafter, an example of the present invention will be specifically described. However, the present invention is not limited to the following description, and can be applied with appropriate modifications within a range not changing the gist of the present invention.

1. Surface-treated zinc oxide powder The surface-treated zinc oxide powder of the present invention is a zinc oxide powder whose surface is treated with an N-acylated amino acid salt. That is, a part or all of the surface of the zinc oxide powder is obtained by treatment with an N-acylated amino acid salt.

The N-acylated amino acid constituting the N-acylated amino acid salt is composed of an amino acid part and a fatty acid part. Examples of amino acids in the amino acid part include glycine, α-alanine, valine, leucine, isoleucine, serine, threonine, lysine, arginine, aspartic acid, glutamic acid, asparagine, glutamine, cysteine, cystine, methionine, phenylalanine, tyrosine, proline, hydroxy Examples include proline, tryptophan, histidine, β-alanine, ε-aminocaproic acid, sarcosine, DL-pyroglutamic acid and the like. Examples of the fatty acid in the fatty acid part include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, and coconut oil fatty acid.

Specific examples of the N-acylated amino acid include lauroyl glutamic acid, myristoyl glutamic acid, coconut oil fatty acid glutamic acid (also referred to as cocoyl glutamic acid), stearoyl glutamic acid, lauroyl aspartic acid, lauroyl sarcosine, myristoyl sarcosine, coconut oil fatty acid sarcosine, N-lauryl. -N-methyl-β-alanine, cocoylalanine, N-myristoyl-N-methyl-β-alanine, N-coconut oil fatty acid-N-methyl-β-alanine, cocoylglycine and the like. Among these, cocoyl glutamic acid is preferable. That is, the N-acylated amino acid salt of the present invention is preferably cocoyl glutamate.

The N-acylated amino acid salt is not particularly limited, and for example, metal salts, ammonium salts, and organic amine salts of N-acylated amino acids are preferable. Examples of metal atoms constituting the metal salt include monovalent metals such as sodium, lithium, potassium, rubidium and cesium; divalent metals such as zinc, magnesium, calcium, strontium and barium; trivalent metals such as aluminum; iron And other metals such as titanium; and the like. Examples of the organic amine group constituting the organic amine salt include alkanolamine groups such as monoethanolamine group, diethanolamine group and triethanolamine group; alkylamine groups such as monoethylamine group, diethylamine group and triethylamine group; ethylenediamine group, And polyamine groups such as a triethylenediamine group. Among the above salts, ammonium salts, sodium salts, and potassium salts are preferable, and sodium salts are more preferable.

In the surface treatment with the N-acylated amino acid salt, the surface treatment is preferably performed at a ratio of 0.1 to 10% by mass in the total amount of the zinc oxide powder after the treatment (surface-treated zinc oxide powder). is there. When the content is 0.1% by mass or more, water repellency and water resistance are further improved. In addition, even if it exceeds 10 mass%, the effect of surface treatment reaches a peak. More preferably, it is 0.2-9 mass%, More preferably, it is 0.5-8 mass%.

Surface treated zinc oxide powder, when measured by infrared spectroscopy, the ratio of the intensity A of the maximum peak at 2895～2953M ^-1, the intensity B of the maximum peak at 870~886cm ^-1 (A / B) is in the range of 0.60 to 1.20. If the intensity ratio (also referred to as IR ratio) is outside the range of 0.60 to 1.20, it cannot be dispersed in an organic solvent and a dispersion cannot be obtained, or a low viscosity dispersion can be obtained. However, the particle size becomes large and may not be suitable for practical use. The IR ratio is preferably 0.65 to 1.50, more preferably 0.70 to 1.20.
In addition, each peak intensity can be calculated | required according to the method described in the Example mentioned later.

Here, it is unclear what the change in the IR ratio specifically indicates, but the maximum peak at 2895 to 2953 cm ⁻¹ is due to molecular movement of the amino acid C—H at 870 to 886 cm ⁻¹ . Since the maximum peak of is attributed to the molecular motion of Zn—O, it is expected to be derived from the chemical interaction between zinc oxide and the surface N-acylated amino acid salt. As shown in the examples described later, the surface treatment amount calculated by subtracting the loss on drying from the loss on ignition is almost the same between the example and the comparative example, so that the N-acylated amino acid salt and zinc oxide are simply different. It is clear that the weight ratio cannot be explained. From this point, it can be estimated as follows.
That is, when the IR ratio (A / B) is in the range of 0.60 to 1.20, the amino acid C—H is not easily stretched and contracted due to steric hindrance. That is, C—H is dense, and therefore the surface treatment with the N-acylated amino acid salt may be uniform.
On the other hand, when the IR ratio is higher than 1.20, the amino acid C—H is likely to undergo stretching vibration. It is considered that there are few steric hindrances, and since many amino acids are separated from each other, it is expected that the treatment with the N-acylated amino acid salt is uneven. Further, when the IR ratio is lower than 0.60, the amount of C—H is originally reduced, so that it is expected that the zinc oxide as the core is exposed and the surface treatment is uneven.
The IR ratio can be controlled by adjusting surface treatment conditions, for example.

The surface-treated zinc oxide powder also does not contain an aluminum element.
“No aluminum element” (also referred to as “non-aluminum”) means that the content of aluminum element in the total mass of the surface-treated zinc oxide powder is 0.1% or less, that is, 0.1% by mass or less. It means that. For example, in a surface-treated inorganic powder, the surface of the inorganic powder is previously coated with aluminum hydroxide or alumina, and then the surface is often treated with another surface treatment agent. Is within the above range, the dispersibility in an organic solvent is lowered, and the particle size and viscosity are remarkably increased when a dispersion is obtained. The reason for this is not clear, but it is probably due to the inhibition of the chemical interaction between zinc oxide and the surface N-acylated amino acid salt.
The content of the aluminum element can be determined by a general elemental analysis method such as using an atomic absorption photometer or an ICP elemental analyzer after being dissolved in a suitable acid such as hydrochloric acid.

The surface-treated zinc oxide powder preferably has an average primary particle size of 1 to 100 nm. Thereby, the ultraviolet shielding property and the visible light transparency can be improved, so that it is more suitable for cosmetic use. More preferably, it is 10-100 nm, More preferably, it is 10-50 nm.
The average primary particle size is a value measured by a method of measuring the primary particle size of 200 particles randomly selected in a scanning electron micrograph (SEM photo) and calculating the average of the primary particle sizes. Means. The diameter of the smallest circumscribed circle is used to calculate the individual primary particle size.

The surface-treated zinc oxide powder preferably has a specific surface area (meaning a BET specific surface area) of 10 to 80 m ² / g. As a result, the strength becomes more satisfactory and the feel becomes better. More preferably, it is 20-70 m < ² > / g, More preferably, it is 25-65 m < ² > / g.
In addition, the said specific surface area can be calculated | required according to the method described in the Example mentioned later.

The shape of the surface-treated zinc oxide powder is not particularly limited, and examples thereof include a spherical shape (including a substantially spherical shape), a rod shape, a needle shape, a spindle shape, a plate shape, a hexagonal plate shape, an acicular aggregate, and an amorphous shape. It is done. Of these, spherical (including substantially spherical) is preferable. The shape can be observed with a scanning electron microscope or the like.

2. Method for producing surface-treated zinc oxide powder In the present invention, the method for treating the surface of zinc oxide powder with an N-acylated amino acid salt (that is, the method for producing the surface-treated zinc oxide powder of the present invention) ratio for the intensity ratio between a given peak by infrared spectroscopy treated zinc oxide powder, and the intensity a of the maximum peak at 2895～2953Cm ^-1, and the intensity of the maximum peak at 870~886cm ^-1 B ( If A / B) is in the range of 0.60 to 1.20, it is not particularly limited, and generally known processing methods are used. Specifically, for example, a method in which an N-acylated amino acid salt is directly mixed with zinc oxide powder (dry treatment method, mechanochemical method), an N-acylated amino acid salt is dispersed in a dispersion medium, and then zinc oxide powder is mixed. Examples thereof include a method of mixing with a body (semi-dry method), a method of mixing a zinc oxide powder in a dispersion medium to prepare a slurry (wet method), and the like.

The raw material zinc oxide powder is not particularly limited, but the average particle size is preferably 1 to 100 nm. More preferably, it is 10-100 nm, More preferably, it is 10-50 nm.
In addition, when measuring the average primary particle diameter of zinc oxide in the slurry, the slurry is filtered, washed with water, and then dried at 105 ° C. for 2 hours using a constant temperature dryer (manufactured by ASONE, SONW-450). Use the particles produced.

The amount of each component used for the surface treatment is preferably set as appropriate so as to satisfy the surface treatment amount described above. Depending on the surface treatment method, loss of the surface treatment agent may occur during or after the treatment. For example, 0.1 to 15 parts by mass of an N-acylated amino acid salt with respect to 100 parts by mass of the zinc oxide powder. It is preferable that More preferably, it is 0.2-12 mass parts, More preferably, it is 0.5-10 mass parts.

In the surface treatment, it is preferable to sufficiently stir so that the raw materials are uniformly mixed. When using a mixer by the dry method or semi-dry method, it is preferable to increase the number of rotations and stir. Although depending on the stirring time, it is preferable to set the number of rotations to, for example, 1000 rpm or more. More preferably, it is 2000 rpm or more. If the rotational speed is 500 rpm or less, the surface treatment may not be successful. The surface treatment temperature is not particularly limited, but for example, from the work surface, it is preferably performed at 5 to 150 ° C, more preferably 60 to 150 ° C.

Although it does not specifically limit as a dispersion medium used with the said semi-dry method and a wet method, For example, water, an organic solvent, or these mixtures etc. are mentioned. Examples of the organic solvent include alcohol, acetone, dimethyl sulfoxide, dimethylformamide, tetrahydrofuran, dioxane and the like. Examples of the alcohol include monovalent water-soluble alcohols such as methanol, ethanol and propanol; bivalent or more such as ethylene glycol and glycerin. Of water-soluble alcohols. The dispersion medium is preferably water, and more preferably ion-exchanged water.

In the above wet method, it is preferable to ripen the slurry at 80 ° C. or higher after preparing the slurry. Thereby, More preferably, it is 85 degreeC or more, More preferably, it is 90 degreeC or more. The upper limit of the aging temperature is preferably 200 ° C. or lower in order to suppress the degradation of amino acids. More preferably, it is 150 degrees C or less, More preferably, it is 130 degrees C or less. It is preferable to age the slurry while stirring.

The aging time is not particularly limited, but is preferably 1 minute or longer. More preferably, it is 5 minutes or more, More preferably, it is 10 minutes or more. The upper limit of the aging time is not particularly limited, but is preferably 10 hours or less from the viewpoint of improving production efficiency, for example. More preferably, it is 5 hours or less, More preferably, it is 2 hours or less.
In the present specification, the aging temperature means the maximum temperature during aging. The aging time means a holding time of the maximum temperature (aging temperature) at the time of aging, and does not include a temperature raising time until the maximum temperature is reached. The temperature raising time is not particularly limited, but is preferably as short as possible.

In the wet method, it is preferable to remove the dispersion medium after aging the slurry. Moreover, you may further perform other processes performed by surface treatment etc. of normal particle | grains other than neutralization, washing | cleaning, grinding | pulverization, etc. as needed.

It is also preferable to perform drying after removing the dispersion medium. Drying includes vacuum drying, heat drying, and the like. When heat drying is performed, it is preferably performed at a temperature of 35 ° C. to 200 ° C. for 5 minutes to 72 hours. By performing the drying, it is expected that the dispersibility of the zinc oxide particles surface-treated with the N-acylated amino acid salt (that is, the surface-treated zinc oxide powder of the present invention) is further improved.

3. Dispersion The dispersion of the present invention contains the above-described surface-treated zinc oxide powder of the present invention and an organic solvent. As described above, since the surface-treated zinc oxide powder has good dispersibility in an organic solvent, the dispersion of the present invention has a state in which the surface-treated zinc oxide powder is uniformly and stably dispersed in the organic solvent. Become. Therefore, a low viscosity can be realized even when a surface-treated zinc oxide powder having a fine particle size is dispersed at a high concentration, which is useful for various uses such as cosmetics. In addition, you may contain another component as needed, and each containing component can use 1 type (s) or 2 or more types, respectively.

The dispersion has a powder concentration of 40% by mass or more. That is, the content (powder concentration) of the surface-treated zinc oxide powder of the present invention is 40% or more of the total mass of the dispersion. Thereby, when a dispersion is used as a raw material in various applications, a sufficient effect can be exhibited with a small amount, which is preferable. From the viewpoint of dispersion stability, it is preferably 40 to 80% by mass, more preferably 50 to 70% by mass.

In the above dispersion, the organic solvent is not particularly limited, and examples thereof include ester oils such as ethylhexyl palmitate and triisodecyl isononanoate; alcohols; liquid paraffins such as hydrogenated polyisobutene; silicone oils such as cyclopentasiloxane and decamethylcyclopentasiloxane. And the like. Among these, silicone oil is preferable, and this makes the dispersion more useful for cosmetic use. The concentration of the organic solvent is 60% by mass or less. That is, it may be 60% or less of the total mass of the dispersion. Preferably it is 10-60 mass%, More preferably, it is 20-60 mass%, More preferably, it is 30-50 mass%.

The dispersion can also contain a dispersant. Since the dispersion can be expected to stabilize the viscosity of the dispersion, suppress the change in the particle size distribution, refine the dispersed particle size, and the like, it is preferably contained.

The type of the dispersant is not particularly limited, and examples thereof include polycarboxylic acid or a salt thereof, alkylsulfonic acid or a salt thereof, alkylbenzenesulfonic acid or a salt thereof, naphthalenesulfonic acid or a salt thereof, polyether alkylsulfonic acid or a salt thereof, Alkyl betaines, polyhydrostearic acids, polyethers or derivatives thereof, polyether alkyl ethers, polyoxyalkylene alkenyl phenyl ethers, sorbitan fatty acid esters, polyether sorbitan fatty acid esters, polyether fatty acid esters, glycerin fatty acid esters, polyether-cured castor Examples thereof include oil, polyether alkylamine, polyether-modified silicone, polyglycerin-modified silicone, polyhydric alcohols, and alkyl-modified polyhydric alcohol. Any of anionic, cationic, and nonionic types may be used, but nonionic type is preferable to prevent chemical reaction with zinc oxide particles, and polyether-modified silicone is more preferable.

The dispersion may further contain other components as necessary. Although it does not specifically limit as another component, For example, antibacterial preservative, an antibacterial agent, etc. are mentioned. These contents are not particularly limited, and are, for example, 20% by mass or less. That is, it is preferably 20% or less of the total mass of the dispersion. More preferably, it is 10 mass% or less.

The dispersion has a D90 in the particle size distribution of 1000 nm or less. Thus, when the dispersion is fine in particle size, for example, when used for cosmetics, the finish when applied to the skin does not become white, and the touch becomes favorable. Preferably it is 950 nm or less, More preferably, it is 930 nm or less.
Note that D90 means a particle size in which the volume cumulative value from the small particle side is 90% of the total particle volume in the particle size distribution. A method for measuring the particle size distribution will be described later in Examples.

The dispersion preferably has a viscosity at 25 ° C. of 500 mPa · s or less. Thereby, it becomes more suitable for various uses, such as cosmetic raw materials. More preferably, it is 400 mPa * s or less, More preferably, it is 300 mPa * s or less.
In addition, a dispersion viscosity can be calculated | required according to the method described in the Example mentioned later.

It does not specifically limit as a manufacturing method for obtaining the said dispersion, What is necessary is just to produce by mixing the component mentioned above. The mixing method is not limited, and a normal method that can be uniformly dispersed may be employed. For example, a disperser / apparatus such as a bead mill or a high-pressure homogenizer may be used.

Since the above-mentioned dispersion has a fine particle size and low viscosity, for example, when used for cosmetics, the finish does not become white, the feel is good, and the water repellency is strong against sweat and water. High cosmetics can be realized. Thus, the cosmetic raw material which consists of a dispersion of this invention is one of this invention. Various compositions containing the dispersion of the present invention (for example, coating compositions and ink compositions in addition to cosmetics) are also invented by the present inventors. Of these, the cosmetic will be described below.

4. Cosmetics The cosmetic of the present invention contains the dispersion of the present invention described above. The manufacturing method of such cosmetics is not specifically limited, What is necessary is just to follow the manufacturing method of normal cosmetics.

The cosmetic is not particularly limited, and examples thereof include skin care products, hair products, makeup products, and UV protection products. Among them, it can be suitably used as a foundation, a sunscreen agent, a makeup base and the like. Also, the shape is not particularly limited, and can be applied to, for example, liquid, emulsion, cream, solid, paste, gel, multilayer, mousse, and spray.

The cosmetic of the present invention is preferably applied to any of water-based cosmetics, O / W type cosmetics (oil-in-water cosmetics), and W / O type cosmetics (water-in-oil cosmetics). Can do. Among them, it is particularly suitable as an oil-in-water cosmetic, and in this case, the surface-treated zinc oxide powder of the present invention can be stably present mainly in the water phase. Therefore, it is preferable because a good feeling of use, water repellency, ultraviolet ray blocking effect, visible light transparency and the like can be stably exhibited.

If necessary, the cosmetic may contain one or more arbitrary aqueous components and oily components that are usually used in the cosmetic field. Although it does not specifically limit as an aqueous component and an oil component, For example, oil agent, surfactant, thickener, antiseptic antibacterial agent, antibacterial agent, preservative, polyhydric alcohol, ultraviolet absorber, ultraviolet shielding agent, antioxidant , Moisturizers, sequestering agents, various extracts, drug components, colorants (dyes, pigments, etc.), pigments, thickeners, pH adjusters, fragrances, cooling agents, antiperspirants, fungicides, skin activation Agents, various powders and the like.

It is not particularly limited as an oil agent, for example, avocado oil, camellia oil, turtle oil, macadamia nut oil, corn oil, mink oil, olive oil, rapeseed oil, egg yolk oil, sesame oil, persic oil, wheat germ oil, Southern oil, castor oil , Linseed oil, safflower oil, cottonseed oil, eno oil, soybean oil, peanut oil, tea seed oil, kaya oil, rice bran oil, Japanese kiri oil, jojoba oil, germ oil, triglycerin, trioctanoic acid glycerin, triisopalmitic acid Glycerin, cacao butter, palm oil, horse oil, palm oil, beef tallow, sheep fat, hardened beef tallow, palm kernel oil, pork tallow, beef bone fat, hardened oil, beef leg fat, owl, hardened castor oil, beeswax, candelilla wax, Cotton wax, Carnauba wax, Bayberry wax, Ibotaro, Whale wax, Montan wax, Nukarou, Lanolin, Kapok wax, Lanolin acetate, Liquid Norin, sugar cane wax, lanolin fatty acid isopropyl, hexyl laurate, reduced lanolin, hard lanolin, shellac wax, POE lanolin alcohol ether, POE lanolin alcohol acetate, POE cholesterol ether, lanolin fatty acid polyethylene glycol, POE hydrogenated lanolin alcohol ether, liquid paraffin, Examples include ozokerite, pristane, paraffin, ceresin, squalene, petrolatum, and microcrystalline wax.

Surfactants include anionic, cationic, nonionic and amphoteric surfactants, but are not particularly limited, and any surfactant that is usually used in cosmetics can be used. Also good.

For example, as the nonionic surfactant, (poly) glycerin fatty acid ester, polyoxyalkylene glycerin fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene sorbit fatty acid ester, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan fatty acid ester , Polyoxyalkylene castor oil, polyoxyalkylene hydrogenated castor oil, polyoxyalkylene sorbitol tetra fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, polyoxyalkylene sterol, polyoxyalkylene alkyl ether, polyoxyalkylene alkyl ether phosphoric acid, etc. In addition, polyoxyalkylene group-containing organopolysiloxane, polyglycerin group-containing organopolysiloxane , Organopolysiloxane of nonionic surfactants sugar chain-containing organopolysiloxane and the like are also mentioned.

The thickening agent is not particularly limited. For example, gum arabic, arabinogalactan, arugeocolloid, carrageenan, caraya gum, agar, guar gum, quince seed (quince), sclerotium gum, starch (rice, corn, potato, wheat) ), Plant polymers such as pectin, tragacanth gum, locust bean gum (carob gum); microbial polymers such as xanthan gum, dextran, succinoglucan and pullulan; animal polymers such as collagen, casein, albumin and gelatin; carboxy Starch polymers such as methyl starch and methylhydroxypropyl starch; methylcellulose, ethylcellulose, methylhydroxypropylcellulose, carboxymethylcellulose, hydroxymethylcellulose, hydroxy Cellulose polymers such as propyl cellulose, sodium cellulose sulfate, sodium carboxymethyl cellulose, crystalline cellulose, cellulose produced by microorganisms, cellulose powder; alginic acid polymers such as sodium alginate and propylene glycol alginate; polyvinyl methyl ether, carboxyvinyl polymer, etc. Vinyl polymers; polyoxyethylene polymers; polyoxyethylene polyoxypropylene copolymer polymers; polyacrylates, copolymers of acrylic acid and alkyl (meth) acrylates and cross polymers, polyacrylamides, alkyl acrylates And acrylic polymers such as acrylamide and acryloyl dimethyl taurate copolymers; other synthetic polymers such as polyethyleneimine and cationic polymers; Semisynthetic polymers such as Ruran; and the like; bentonite, aluminum magnesium silicate, montmorillonite, beidellite, nontronite, laponite, hectorite, inorganic polymers such as anhydrous silicic acid.

The antiseptic antibacterial agent and antibacterial agent are not particularly limited. For example, paraoxybenzoic acid alkyl ester, benzoic acid, sodium benzoate, sorbic acid, potassium sorbate, phenoxyethanol, salicylic acid, coalic acid, sorbic acid, parachlorometacresol, hexachloro Examples include phen, benzalkonium chloride, chlorhexidine chloride, photosensitizer, and phenoxyethanol.

In order to describe the present invention in detail, examples are given below, but the present invention is not limited to these examples. Unless otherwise specified, “%” means “mass% (weight%)” and “part” means “part by mass (weight part)”.
Various physical properties were evaluated as follows.

1. Physical properties of powder (1) Loss on drying (%)
2 g of the powder was precisely weighed to 3 digits after the decimal point, dried at 120 ° C. for 2 hours, and calculated from the weight difference before and after drying.

(2) Loss on ignition (%)
2 g of powder was precisely weighed to 3 digits after the decimal point, ignited at 500 ° C. for 1 hour, and calculated from the weight difference before and after ignition.

(3) Specific surface area (m ² / g)
Measurement was performed at 130 ° C. for 5 minutes using a fully automatic specific surface area measuring device (Macsorb HM model-1220) manufactured by Mountec.

(4) IR ratio (A / B)
Largest in using, ATR method at (diamond prism), and the intensity A of the maximum peak at ^{2895~2953cm -1, 870~886cm -1: FT-} IR ( Thermo Fisher made Scientific Nicolet iS 10) The peak intensity B was measured.

(5) Average particle diameter (average primary particle diameter)
The average primary particle size was determined according to the method described above.

2, 50 g of dispersion physical powder, 6 g of PEG-9 polydimethylsiloxyethyl dimethicone (Shin-Etsu Chemical Co., Ltd., KF-6028P), 44 g of decamethylcyclobentasiloxane were blended in a mayonnaise bottle, and 100 g of zirconia beads having a diameter of 0.5 mm were mixed. And a dispersion was prepared by dispersing for 60 minutes in a paint shaker. For this dispersion, the viscosity and particle size (distribution) were determined as follows.

(1) Viscosity (mPa · s)
It was measured with a B-type viscometer (manufactured by Eiko Seiki Co., Ltd., rotor No. 3, rotation speed 12 rpm). The measurement temperature was 25 ° C.

(2) Particle size (distribution)
The particle size distribution was measured with a laser diffraction particle size distribution analyzer (LA-750: manufactured by Horiba, Ltd.). D10, D50, and D90 in the table mean 10% integrated diameter, 50% integrated diameter (also referred to as median diameter), and 90% integrated diameter on a volume basis, respectively.

Example 1
100 g of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., FINEX-50, average primary particle size 20 nm) is put in a mixer (Powder Lab, manufactured by Nippon Coke Industries, Ltd.), 50 g of an aqueous solution in which 6 g of sodium cocoyl glutamate is dissolved is added, and 10 g at 2000 rpm. Mixed for minutes. Thereafter, the number of revolutions was changed to a predetermined number X, the inside of the tank was raised to a predetermined temperature Y while stirring, and further a negative pressure was removed with a vacuum pump to remove volatile components such as water to obtain a powder. The physical properties of the obtained powder were evaluated. X and Y are shown in Table 1, and the evaluation results are shown in Table 2. Moreover, the dispersion was prepared using the powder as described above, and the physical properties were evaluated. The results are also shown in Table 2.

Examples 2 and 3, Comparative Examples 1 and 2
Each powder was obtained in the same manner as in Example 1 except that X and Y were changed as shown in Table 1. The evaluation results of the physical properties of the powder and dispersion are shown in Table 2.

Comparative Example 3
Zinc oxide (FINEX-50, average primary particle size 20 nm, manufactured by Sakai Chemical Industry Co., Ltd.) was used as the powder of Comparative Example 3. The evaluation results of the physical properties of this powder and dispersion are shown in Table 2.

Comparative Example 4
100 g of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., FINEX-50, average primary particle size 20 nm) was repulped into 500 ml of pure water and stirred for 30 minutes. This is called zinc oxide repulp liquid.
A solution obtained by diluting 22 mL of an aqueous sodium aluminate solution (added 244.1 g / L as Al ₂ O ₃ concentration, 5.26 g in terms of Al ₂ O ₃ and 8.0 g in terms of Al (OH) ₃ ) with 500 ml of water (dilution) Two dilutions were prepared: liquid A) and a liquid obtained by diluting 40 ml of sulfuric acid with 500 ml of water (referred to as dilution B).
While the diluent A was added dropwise to the zinc oxide repulp solution at 8 ml / min, at the same time, the diluent B was added dropwise at room temperature while adjusting the dropping rate so that the pH of the entire zinc oxide repulp solution was maintained at 8-9. When the addition of the diluent A was completed, the addition of the diluent B was completed, and the mixture was aged with stirring for 30 minutes. The reaction solution was filtered, and the obtained cake was washed with water until the electric conductivity became 100 μS / cm or less, and dried at 130 ° C. for 12 hours.
A powder (surface-treated product with sodium cocoyl glutamate) was obtained in the same manner as in Example 1 except that the dried product thus obtained was used instead of zinc oxide. The evaluation results of the physical properties of this powder and dispersion are shown in Table 2.
The composition ratio of this powder was zinc oxide / Al (OH) ₃ / sodium cocoyl glutamate = 87/7/6 (mass%).

In Table 2, “Ignition-drying” marked with * 1 is the difference between loss on ignition and loss on drying. This corresponds to the surface treatment amount of the powder.

From Table 2, the following was confirmed.
The powder obtained in Examples 1 to 3 has a surface treated with an N-acylated amino acid salt, and has an IR ratio (A / B) of 0.60 to 1 when measured by infrared spectroscopy. This corresponds to the surface-treated zinc oxide powder having the constitution of the present invention which is within the range of 20 and does not contain an aluminum element. In contrast, the powders obtained in Comparative Examples 1 and 2 are examples in which the IR ratio exceeds 1.20. In this case, it can be seen that the particle size contained in the dispersion is remarkably increased. On the other hand, the powder of Comparative Example 3 is an example having an IR ratio of less than 0.60. However, such a powder could not be dispersed in a solvent, that is, the dispersion could not be finished. Comparative Example 4 is a powder containing an aluminum element. In this case, the dispersion had a high viscosity, and the particle size of the contained powder was remarkably large. Therefore, it has been found that the dispersibility in an organic solvent is improved only when the surface-treated zinc oxide powder has the above-described configuration of the present invention, and furthermore, a dispersion having a fine particle size and a low viscosity can be provided.
Furthermore, in order to adjust to the IR ratio, it has been found that adjustment by the number of rotation of the mixer blades when mixing with a mixer is necessary. Although the cause is unknown, it is presumed that optimum conditions exist depending on the treatment method in order to stably treat the N-acylated amino acid salt.

Claims (6)

The surface is treated with an N-acylated amino acid salt;
When measured by infrared spectroscopy, and strength A of the maximum peak at 2895～2953Cm ^-1, the ratio between the intensity B of the maximum peak at 870~886cm ^-1 (A / B) is 0.60 to 1 .20, and
A surface-treated zinc oxide powder characterized by not containing an aluminum element. 2. The surface-treated zinc oxide powder according to claim 1, wherein an average primary particle size of the powder is 10 to 100 nm. The surface-treated zinc oxide powder according to claim 1 or 2, wherein the N-acylated amino acid salt is cocoyl glutamate. A dispersion comprising the surface-treated zinc oxide powder according to any one of claims 1 to 3 and an organic solvent,
The dispersion is
D90 in the particle size distribution is 1000 nm or less,
A dispersion having a powder concentration of 40% by mass or more. The dispersion according to claim 4, wherein the organic solvent contains silicone oil. A cosmetic comprising the dispersion according to claim 4 or 5.