WO2022137786A1

WO2022137786A1 - Zinc oxide dispersion, titanium oxide dispersion, and cosmetic composition

Info

Publication number: WO2022137786A1
Application number: PCT/JP2021/039486
Authority: WO
Inventors: 聡一郎森川; 園子相良
Original assignee: 株式会社Ｓｃｒｅｅｎホールディングス
Priority date: 2020-12-24
Filing date: 2021-10-26
Publication date: 2022-06-30
Also published as: JP2022100722A

Abstract

Provided are a zinc oxide dispersion, a titanium oxide dispersion and a cosmetic composition, each of which has excellent dispersibility and each of which does not undergo the formation of coarse particles due to the reaggregation of excessively dispersed particles of zinc oxide particles or titanium oxide particles while maintaining excellent biological detrimental properties. The zinc oxide dispersion of the present invention comprises zinc oxide particles, sodium polyacrylate having a mass average molecular weight of less than 10,000, and a dispersion medium only composed of water, propylene glycol and/or glycerin, in which the blend ratio of propylene glycol to the dispersion medium is 0.3/1 to 0.9/1, and the blend ratio of glycerin to the dispersion medium is 0.1/1 to 0.8/1; and the titanium oxide dispersion comprises titanium oxide particles, the sodium polyacrylate, and a dispersion medium only composed of water, 1,3-butylene glycol and/or glycerin, in which the blend ratio of 1,3-butylene glycol to the dispersion medium is 0.1/1 to 0.9/1 and the blend ratio of glycerin to the dispersion medium is 0.1/1 to 0.9/1.

Description

Zinc oxide dispersion, titanium oxide dispersion and cosmetic composition

The present invention relates to a zinc oxide dispersion, a titanium oxide dispersion and a cosmetic composition. More specifically, the present invention maintains good biotoxicity and suppresses the formation of coarse particles due to reaggregation of overdispersed particles. The present invention relates to a dispersion, a titanium oxide dispersion and a cosmetic composition.

Zinc oxide particles or titanium oxide particles (hereinafter referred to as "zinc oxide particles, etc.") are dispersed in a nanometer-sized average dispersed particle size, and the zinc oxide particles and titanium oxide particles function as an ultraviolet shielding agent. Therefore, it is used in cosmetic compositions such as sunscreens. Further, the dispersion in which zinc oxide particles and the like are dispersed makes it possible to simplify the manufacturing process of the cosmetic composition and improve the quality.

On the other hand, in recent years, there has been an increasing demand for dispersions that can be blended with sunscreens of O / W (oil-in-water) type emulsions and have low biotoxicity. Therefore, the demand for dispersions such as zinc oxide particles is increasing, but in the case of sunscreens using the dispersions, the dispersed particle diameters of the dispersed zinc oxide particles and the like are not sufficiently small. Therefore, when this is applied on the skin, there is a problem that a white film remains on the skin at the time of application and after application, that is, so-called whitening occurs. Further, when the cosmetic composition containing a dispersion of zinc oxide particles or the like is allowed to stand for a certain period of time, there is also a problem that the zinc oxide particles or the like settle.

To solve this problem, for example, in Patent Document 1, a pigment composition using sodium polyacrylate having a mass average molecular weight of 10,000 or less as a dispersant and zinc oxide particles having a surface texture compatible with the dispersant as a pigment. The thing is listed. According to Patent Document 1, the average dispersed particle size D50 of the zinc oxide particles dispersed in the pigment composition can be suppressed to a sufficiently small value, and as a result, the pigment composition is used as an aqueous ink composition for inkjet. In addition, it is described that it can be applied to cosmetic compositions.

However, even with the pigment composition described in Patent Document 1, the suppression of overdispersion in which dispersed zinc oxide particles reaggregate is not sufficient. Therefore, in the pigment composition described in Patent Document 1, there is a problem that the value of the dispersed particle size D99 (the particle size of 99% in the integrated particle size distribution in the volume integrated particle size distribution) of the zinc oxide particles may be large.

Japanese Unexamined Patent Publication No. 2018-188518

The present invention has been made in view of the above problems, and an object thereof is to suppress the formation of coarse particles due to reaggregation of zinc oxide particles or overdispersed particles of titanium oxide particles while maintaining excellent biotoxicity. Further, it is an object of the present invention to provide a zinc oxide dispersion, a titanium oxide dispersion and a cosmetic composition having excellent dispersibility.

In order to solve the above-mentioned problems, the zinc oxide dispersion according to the present invention comprises zinc oxide particles, a dispersant of the zinc oxide particles composed of sodium polyacrylate having a mass average molecular weight of less than 10,000, and the zinc oxide particles. The dispersion medium comprises only water and propylene glycol and / or glycerin, and the compounding ratio of the propylene glycol to the dispersion medium (propylene glycol / dispersion medium) is 0 on a mass basis. It is in the range of .3 / 1 to 0.9 / 1, and the compounding ratio of the glycerin to the dispersion medium (glycerin / dispersion medium) is in the range of 0.1 / 1 to 0.8 / 1 on a mass basis. It is characterized by being.

According to the above configuration, sodium polyacrylate having a mass average molecular weight of 10,000 or less is used as a dispersant for zinc oxide particles, and only water, propylene glycol and / or glycerin are used as a dispersion medium for dispersing zinc oxide particles. Use things. With such a configuration, it is possible to suppress the formation of coarse particles due to the reaggregation of overdispersed zinc oxide particles. As a result, it is possible to provide a zinc oxide dispersion in which the value of the average dispersed particle size D99 (the particle size of 99% in the integrated particle size distribution in the volume integrated particle size distribution) is significantly reduced as compared with the conventional case. Further, the dispersion medium of the present invention is a mixed solvent in which water is mixed with propylene glycol and / or glycerin, and even when only water is used as the dispersion medium, good biotoxicity can be maintained. Be done.

Further, in the above configuration, the compounding ratio of propylene glycol to the dispersion medium is in the range of 0.3 / 1 to 0.9 / 1 on a mass basis, and the compounding ratio of glycerin to the dispersion medium is 0.1 / 1 on a mass basis. It shall be within the range of ~ 0.8 / 1. By setting the blending ratio of propylene glycol to 0.3 / 1 or more and the blending ratio of glycerin to 0.1 / 1 or more, the wettability of sodium polyacrylate adsorbed on the surface of zinc oxide particles to the dispersion medium is improved. Can be made to. As a result, the zinc oxide particles on which sodium polyacrylate is adsorbed are wetted on the surface, and the decrease in the cohesive force is promoted. As a result, reaggregation due to overdispersion of the zinc oxide particles can be suppressed or reduced, and the value of the dispersed particle diameter D99 of the zinc oxide particles can be prevented from increasing. Further, by setting the blending ratio of propylene glycol to 0.9 / 1 or less and the blending ratio of glycerin to 0.8 / 1 or less, it is possible to prevent the viscosity of the zinc oxide dispersion from becoming too high.

Further, in the above configuration, the zinc oxide particles are preferably zinc oxide particles that have not been surface-treated. As a result, it is possible to suppress the increase in the average dispersed particle size of the dispersed zinc oxide particles and bring the zinc oxide particles closer to the average primary particle size. In addition, it is possible to prevent a decrease in storage stability.

Further, in the above configuration, it is preferable that the content ratio of the zinc oxide particles and the sodium polyacrylate is in the range of 1: 0.01 to 1: 0.5 on a mass basis. By setting the content ratio to 1: 0.01 or more, it is possible to prevent a decrease in the dispersibility of the zinc oxide particles. On the other hand, by setting the content ratio to 1: 0.5 or less, it is possible to prevent a decrease in the dispersion stability of the zinc oxide particles.

Further, in the above configuration, it is preferable that the average dispersed particle diameter D99 of the dispersed zinc oxide particles is 350 nm or less. As a result, the separation, sedimentation and aggregation of zinc oxide particles can be prevented, and the storage stability of the zinc oxide dispersion can be maintained.

In order to solve the above-mentioned problems, the titanium oxide dispersion according to the present invention comprises titanium oxide particles, a dispersant of the titanium oxide particles composed of sodium polyacrylate having a mass average molecular weight of less than 10,000, and the titanium oxide particles. The dispersion medium comprises only water and 1,3-butylene glycol and / or glycerin, and the compounding ratio of the 1,3-butylene glycol to the dispersion medium (1,3-butylene glycol). Butylene glycol / dispersion medium) is in the range of 0.1 / 1 to 0.9 / 1 on a mass basis, and the compounding ratio of the glycerin to the dispersion medium (glycerin / dispersion medium) is 0. It is characterized in that it is in the range of 1/1 to 0.9 / 1.

According to the above configuration, sodium polyacrylate having a mass average molecular weight of 10,000 or less is used as a dispersant for titanium oxide particles, and water and 1,3-butylene glycol and / or glycerin are used as a dispersion medium for dispersing titanium oxide particles. Use only those consisting of and. Thereby, in the above configuration, it is possible to suppress the formation of coarse particles due to the reaggregation of the overdispersed titanium oxide particles. As a result, with the above configuration, it is possible to provide a titanium oxide dispersion in which the value of the average dispersed particle size D99 (particle size of 99% in the integrated particle size distribution in the volume integrated particle size distribution) is significantly reduced as compared with the conventional case. Further, the dispersion medium of the present invention is a mixed solvent in which water and 1,3-butylene glycol and / or glycerin are mixed, and the skin irritation is reduced as compared with the case where propylene glycol is used as the dispersion medium, for example. can do. Further, the titanium oxide dispersion of the present invention can maintain good biotoxicity as compared with the case of using a dispersion medium consisting only of water.

Further, in the above configuration, the compounding ratio of 1,3-butylene glycol to the dispersion medium is in the range of 0.1 / 1 to 0.9 / 1 on the mass basis, and the compounding ratio of glycerin to the dispersion medium is 0 on the mass basis. It shall be in the range of 1/1 to 0.9 / 1. By setting the blending ratio of 1,3-butylene glycol to 0.1 / 1 or more and the blending ratio of glycerin to 0.1 / 1 or more, the dispersion medium of sodium polyacrylate adsorbed on the surface of the titanium oxide particles is used. Wetness can be improved. As a result, the titanium oxide particles on which sodium polyacrylate is adsorbed are wetted, and the decrease in cohesive force is promoted. As a result, reaggregation due to overdispersion of the titanium oxide particles can be suppressed or reduced, and the value of the dispersed particle diameter D99 of the titanium oxide particles can be prevented from increasing. Further, by setting the blending ratio of 1,3-butylene glycol to 0.9 / 1 or less and the blending ratio of glycerin to 0.9 / 1 or less, it is possible to prevent the viscosity of the titanium oxide dispersion from becoming too high. be able to.

Further, in the above configuration, the titanium oxide particles are preferably titanium oxide particles that have not been surface-treated. This suppresses the increase in the average dispersed particle size of the dispersed titanium oxide particles and makes it possible to approach the average primary particle size. In addition, it is possible to prevent a decrease in storage stability.

Further, in the above configuration, the content ratio of the titanium oxide particles to the sodium polyacrylate is preferably in the range of 1: 0.01 to 1: 0.5 on a mass basis. By setting the content ratio to 1: 0.01 or more, it is possible to prevent a decrease in the dispersibility of the titanium oxide particles. On the other hand, by setting the content ratio to 1: 0.5 or less, it is possible to prevent a decrease in the dispersion stability of the titanium oxide particles.

Further, in the above configuration, it is preferable that the average dispersed particle diameter D99 of the dispersed titanium oxide particles is 350 nm or less. As a result, the separation, sedimentation and aggregation of the titanium oxide particles can be prevented, and the storage stability of the titanium oxide dispersion can be maintained.

The cosmetic composition according to the present invention is characterized by containing the zinc oxide dispersion or the titanium oxide dispersion in order to solve the above-mentioned problems.

The zinc oxide dispersion and the titanium oxide dispersion in the above configuration are dispersions in which the values of the average dispersed particle diameter D99 of the zinc oxide particles and the titanium oxide particles to be dispersed are significantly reduced as compared with the conventional dispersion. be. Therefore, the cosmetic composition of the present invention containing these dispersions reduces or prevents the occurrence of so-called whitening, in which a white film remains on the skin during and after application, as compared with the conventional cosmetic composition. Can be done.

According to the present invention, sodium polyacrylate having a mass average molecular weight of 10,000 or less is used as a dispersant for zinc oxide particles, and a mixed solvent consisting only of water and propylene glycol and / or glycerin as a dispersion medium for dispersing zinc oxide particles. Is used. As a result, it is possible to suppress the reaggregation of the overdispersed zinc oxide particles to form coarse particles, and reduce the value of the average dispersed particle diameter D99 of the zinc oxide particles. Propylene glycol and glycerin used as dispersion media are compounds having safety to the human body. Therefore, according to the present invention, it is possible to provide a zinc oxide dispersion having excellent dispersibility while maintaining good biotoxicity. Further, according to the present invention, it is possible to provide a cosmetic composition in which the occurrence of whitening is reduced or prevented by containing the zinc oxide dispersion.

Further, according to the present invention, sodium polyacrylate having a mass average molecular weight of 10,000 or less is used as a dispersant for titanium oxide particles, and water and 1,3-butylene glycol and / or glycerin are used as a dispersion medium for dispersing titanium oxide particles. A mixed solvent consisting only of and is used. As a result, it is possible to suppress the reaggregation of the overdispersed titanium oxide particles to form coarse particles, and reduce the value of the average dispersed particle diameter D99 of the titanium oxide particles. Further, 1,3-butylene glycol and glycerin used as a dispersion medium are compounds having safety to the human body. In particular, 1,3-butylene glycol can reduce the skin irritation of the titanium oxide dispersion as compared with the case of using propylene glycol, for example. Therefore, according to the present invention, it is possible to provide a titanium oxide dispersion having excellent dispersibility while maintaining good biotoxicity. Further, according to the present invention, it is possible to provide a cosmetic composition capable of reducing or preventing the occurrence of whitening and reducing skin irritation by containing the titanium oxide dispersion.

(Zinc oxide dispersion and its manufacturing method)
The zinc oxide dispersion according to the present embodiment contains at least zinc oxide (ZnO) particles as a dispersant, sodium polyacrylate as a dispersant for zinc oxide particles, and a dispersion medium.

Examples of the zinc oxide particles include zinc oxide particles surface-treated with a compound such as silicon dioxide hydrate (hydrous silica), hydrogen dimethicone, triethoxycaprylylsilane, and aluminum hydroxide, and the surface treatment thereof. Examples include zinc oxide particles that have not been treated. Of these zinc oxide particles, it is preferable to use zinc oxide particles that have not been surface-treated in the present embodiment. When the zinc oxide particles are not surface-treated, the average dispersed particle size of the zinc oxide particles can be further reduced as compared with the surface-treated zinc oxide particles, and good storage stability is maintained. be able to. Further, the average dispersed particle size of the dispersed zinc oxide particles can be brought close to the average primary particle size of the zinc oxide particles. In the present invention, the zinc oxide particles mean crystalline zinc oxide particles unless otherwise specified.

Commercially available products can also be used as the zinc oxide particles, and such commercially available products include, for example, NANOFINE-50LP, FINEX-33W, FINEX-52W-LP2, FINEX-33W-LP2, and FINEX-50S-LP2. , FINEX-30S-LPT, FINEX-50-OTS, FINEX-50, FINEX-30, FINEX-25 (all trade names, manufactured by Sakai Chemical Industry Co., Ltd.) and the like. Among these commercially available products, in the present embodiment, FINEX-50, FINEX-30 and FINEX-25 which have not been surface-treated are preferable.

The average primary particle diameter (volume average particle diameter) of the zinc oxide particles is preferably 20 nm to 400 nm, more preferably 30 nm to 200 nm, and particularly preferably 40 nm to 100 nm. By setting the average primary particle diameter to 20 nm or more, transparency can be improved and sufficient concealment can be ensured. On the other hand, by setting the average primary particle diameter to 400 nm or less, coarse particles can be reduced and zinc oxide particles can be prevented from settling.

In the present specification, the "average primary particle size" means the average particle size of the primary particles, and the primary particles generally refer to the smallest particles constituting the powder, and are single crystals or close to them. It means that it includes particles formed by aggregating crystallites.

The average primary particle diameter is an arithmetic average diameter obtained by observing zinc oxide particles with an electron microscope. In the present embodiment, zinc oxide particles having a monodisperse particle size distribution are used, but the present invention is not limited to this, and zinc oxide particles having a polydisperse particle size distribution may be used. Further, two or more kinds of zinc oxide particles having a monodisperse particle size distribution may be mixed and used.

The shape of the zinc oxide particles is not particularly limited, and any shape such as spherical, rod-shaped, needle-shaped, spindle-shaped, and plate-shaped can be used. In this embodiment, zinc oxide particles having the same shape may be used, or two or more different shapes may be mixed and used. The average primary particle diameter in the case of rod-shaped, needle-shaped, or spindle-shaped particles is defined by a geometric mean value of the length (or height) of the major axis and the length (or width) of the minor axis.

Since the content of zinc oxide particles directly affects the concentration of the zinc oxide dispersion and affects the storage stability, viscosity, pH, etc. of the cosmetic composition described later, these points should be taken into consideration. It may be set appropriately. Usually, it is preferably in the range of 10% by mass to 70% by mass, more preferably in the range of 20% by mass to 50% by mass, and in the range of 30% by mass to 40% by mass with respect to the total mass of the zinc oxide dispersion. More preferred. By setting the content of zinc oxide particles to 10% by mass or more, it is possible to suppress a decrease in concentration. On the other hand, by setting the content of the zinc oxide particles to 70% by mass or less, it is possible to prevent the dispersibility of the zinc oxide particles from being lowered and the handleability from being deteriorated due to the increase in viscosity.

In the zinc oxide dispersion, sodium polyacrylate functions as a dispersant for zinc oxide particles. By blending sodium polyacrylate, the dispersibility of zinc oxide particles can be improved. In addition, sodium polyacrylate conforms to the standards stipulated by the Pharmaceutical Affairs Law and the like. Therefore, by using sodium polyacrylate as a dispersant, the biotoxicity of the zinc oxide dispersion can be reduced.

The mass average molecular weight of sodium polyacrylate is 10,000 or less, preferably 1500 to 10000, and more preferably 2000 to 8000. By setting the mass average molecular weight of sodium polyacrylate to 10,000 or less, it is possible to prevent the molecular chain of sodium polyacrylate adhering to the surface of the zinc oxide particles from becoming excessively long. As a result, it is possible to reduce the possibility that the zinc oxide particles are crosslinked and aggregated. By setting the mass average molecular weight of sodium polyacrylate to 1500 or more, it is possible for sodium polyacrylate adsorbed on the surface of zinc oxide particles to sufficiently exert a repulsive force due to steric damage or the like. As a result, it is possible to prevent the zinc oxide particles from reaggregating with each other. The mass average molecular weight of sodium polyacrylate is, for example, a value obtained by the measuring method described in Examples described later.

The content ratio of the zinc oxide particles of the present embodiment to sodium polyacrylate is preferably 1: 0.01 to 1: 0.5 on a mass basis, and 1: 0.02 to 1: 0.2. Is more preferable. By setting the content ratio to 1: 0.01 or more, it is possible to prevent a decrease in the dispersibility of the zinc oxide particles. On the other hand, by setting the content ratio to 1: 0.5 or less, it is possible to prevent a decrease in the dispersion stability of the zinc oxide particles.

Note that sodium polyacrylate is relatively less likely to generate bubbles when added to a dispersion medium described later, for example, as compared with other conventional dispersants. Therefore, in the zinc oxide dispersion of the present embodiment, the addition of the defoaming agent can be omitted.

The zinc oxide dispersion according to the present embodiment contains a dispersion medium for dispersing zinc oxide particles, and the dispersion medium includes a mixed solvent consisting only of water and propylene glycol and / or glycerin. Used.

Examples of water include pure water such as ion-exchanged water, ultrafiltration water, reverse osmosis water, and distilled water, or water from which ionic impurities such as ultrapure water have been removed. In particular, water sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide is suitable because it can prevent the growth of mold and bacteria for a long period of time.

The compounding ratio of propylene glycol to the dispersion medium (propylene glycol / dispersion medium) is in the range of 0.3 / 1 to 0.9 / 1 on a mass basis, and is preferably 0.4 / 1 to 0.8 / 1. , More preferably 0.5 / 1 to 0.7 / 1. The compounding ratio of glycerin to the dispersion medium (glycerin / dispersion medium) is in the range of 0.1 / 1 to 0.8 / 1 on a mass basis, preferably 0.1 / 1 to 0.7 / 1. , More preferably 0.1 / 1 to 0.6 / 1. Dispersion of sodium polyacrylate adsorbed on the surface of zinc oxide particles by setting the blending ratio of propylene glycol to the dispersion medium of 0.3 / 1 or more and the blending ratio of glycerin to the dispersion medium of 0.1 / 1 or more. The wettability to the medium can be improved. As a result, the zinc oxide particles on which sodium polyacrylate is adsorbed are wetted on the surface, and the decrease in the cohesive force is promoted. As a result, reaggregation due to overdispersion of zinc oxide particles can be suppressed or reduced, and the value of the average dispersed particle size D99 of zinc oxide particles (99% of the integrated particle size in the volume integrated particle size distribution) becomes large. Can be prevented. On the other hand, by setting the blending ratio of propylene glycol to the dispersion medium to 0.9 / 1 or less and the blending ratio of glycerin to the dispersion medium to 0.8 / 1 or less, the viscosity of the zinc oxide dispersion becomes too large. Can be prevented.

The content of the dispersion medium is preferably in the range of 29% by mass to 89% by mass, more preferably in the range of 50% by mass to 80% by mass, and 60% by mass to 70% by mass with respect to the total mass of the zinc oxide dispersion. The range of% is particularly preferable.

The average dispersed particle size D10 of the dispersed zinc oxide particles (particle size of 10% in the integrated particle size distribution in the volume-based integrated particle size distribution) is preferably in the range of 5 nm to 100 nm, more preferably in the range of 10 nm to 60 nm. preferable. The average dispersed particle size D50 of the zinc oxide particles (particle size of 50% in the integrated particle size distribution in the volume-based integrated particle size distribution) is preferably in the range of 20 nm to 500 nm, and more preferably in the range of 40 nm to 100 nm. Further, the dispersed particle size D99 of the zinc oxide particles (the particle size of 99% in the integrated particle size distribution in the volume integrated particle size distribution) is preferably 350 nm or less, more preferably 30 nm to 300 nm, and particularly preferably 50 nm to 200 nm. By setting D10 to 5 nm or more or D50 to 20 nm or more, deterioration of the storage stability of the zinc oxide dispersion can be prevented. On the other hand, by setting D10 to 100 nm or less, D50 to 500 nm or less, or D99 to 350 nm or less, separation, sedimentation and aggregation of zinc oxide particles can be prevented, and the storage stability of the zinc oxide dispersion can be maintained. The average dispersed particle diameters D10, D50 and D99 of the zinc oxide particles are values measured by a dynamic light scattering method using Microtrac UPA-EX150 (trade name, manufactured by Nikkiso Co., Ltd.).

In the method for producing a zinc oxide dispersion of the present embodiment, the mixing method and the order of addition of zinc oxide particles, sodium polyacrylate, a dispersion medium and other additives to be blended as necessary are not particularly limited. For example, a mixed solvent consisting only of zinc oxide particles, sodium polyacrylate and water as a dispersion medium and propylene glycol and / or glycerin is mixed at a time, and the mixed solution is subjected to dispersion treatment using a normal disperser. May be.

Here, the term "dispersion treatment" as used herein means that a mixture containing zinc oxide particles, sodium polyacrylate, a dispersion medium and other additives to be blended as necessary is finely pulverized by a wet dispersion method. It means distributed processing. The disperser used for the dispersion treatment is not particularly limited, and examples thereof include a ball mill, a roll mill, a sand mill, a bead mill, a paint shaker, and a nanomizer.

The dispersion time in the dispersion processing is not particularly limited, and may be appropriately set so that at least one of D10, D50, and D99 has a target value.

In the present embodiment, by using sodium polyacrylate as a dispersant for zinc oxide particles, it is possible to suppress the generation of bubbles in the zinc oxide dispersion. Therefore, the defoaming step for reducing or eliminating the bubbles can be omitted, and the manufacturing efficiency can be further improved. Further, since the inclusion of the defoaming agent can be omitted, the production of the zinc oxide dispersion becomes easier.

The zinc oxide dispersion of the present embodiment includes not only the form of the final product cosmetic composition (details will be described later) but also the form of the dispersion liquid for preparing the cosmetic composition.

(Titanium oxide dispersion and its manufacturing method)
The titanium oxide dispersion according to the present embodiment contains at least titanium oxide (TiO ₂ ) particles as a dispersant, sodium polyacrylate as a dispersant for the titanium oxide particles, and a dispersion medium.

The titanium oxide particles are used as a white pigment, have an ultraviolet shielding function, have a small specific gravity and a large refractive index as compared with other known white pigments. Titanium oxide particles are also chemically and physically stable. Therefore, the titanium oxide particles are excellent in hiding and coloring properties, and are also excellent in durability against acids, alkalis, and other environments.

In the present embodiment, the titanium oxide particles having a crystal structure of anatase type (tetragonal crystal), rutile type (tetragonal crystal) or blue kite type (orthorhombic crystal) can be used. However, when the titanium oxide dispersion of the present embodiment is applied to a cosmetic composition, titanium oxide having a rutile-type crystal structure is preferable from the viewpoint of improving concealment. Further, titanium oxide having a rutile-type crystal structure has a high refractive index of visible light (wavelength range 360 nm to 830 nm), so that color development can be improved. On the other hand, since titanium oxide having an anatase-type crystal structure has a function as a photocatalyst, when this is used for the titanium oxide dispersion of the present embodiment, the function of a photocatalyst can be added. In the present invention, the titanium oxide particles mean crystalline titanium oxide particles unless otherwise specified.

Examples of the titanium oxide particles include titanium oxide particles surface-treated with a compound such as silicon dioxide hydrate (hydrous silica), hydrogen dimethicone, triethoxycaprylylsilane, aluminum hydroxide, and stearic acid. Examples thereof include titanium oxide particles that have not been surface-treated. Of these titanium oxide particles, it is preferable to use titanium oxide particles that have not been surface-treated in the present embodiment. Hydroxyl groups are usually present on the surface of unsurface-treated titanium oxide particles. Therefore, the surface of the titanium oxide particles is hydrophilic. Therefore, by using the titanium oxide particles that have not been surface-treated, it is possible to bring the average dispersed particle size of the dispersed titanium oxide particles closer to the average primary particle size of the titanium oxide particles. In the present invention, "hydrophilic" means that a functional group or the like having an affinity for water is present on the surface of the titanium oxide particles.

Commercially available products can be used as the titanium oxide particles, and such commercially available products include, for example, STR-100A-LP, STR-100C-LP, STR-100W-LP, STR-100C-LF, and STR. -100W-OTS, STR-100W (G), STR-40-OTS, STR-40N, STR-100N (trade names, all manufactured by Sakai Chemical Industry Co., Ltd.) and the like can be mentioned. Among these commercially available products, in the present embodiment, STR-40N and STR-100N which have not been surface-treated are preferable.

The average primary particle diameter (volume average particle diameter) of the titanium oxide particles is preferably 20 nm to 400 nm, more preferably 30 nm to 200 nm, and particularly preferably 40 nm to 100 nm. By setting the average primary particle size to 20 nm or more, transparency can be improved. In addition, sufficient concealment can be ensured. On the other hand, by setting the average primary particle diameter to 400 nm or less, coarse particles can be reduced and precipitation of titanium oxide particles can be prevented.

The average primary particle diameter is an arithmetic average diameter obtained by observing titanium oxide particles with an electron microscope. In the present embodiment, titanium oxide particles having a monodisperse particle size distribution are used, but the present invention is not limited to this, and titanium oxide particles having a polydisperse particle size distribution may be used. Further, two or more kinds of pigments having a monodisperse particle size distribution may be mixed and used.

The shape of the titanium oxide particles is not particularly limited, and any shape such as a spherical shape, a rod shape, a needle shape, a spindle shape, and a plate shape can be used. In the present embodiment, titanium oxide particles having the same shape may be used, or two or more different shapes may be mixed and used. The average primary particle diameter in the case of rod-shaped, needle-shaped, or spindle-shaped particles is defined by a geometric mean value of the length (or height) of the major axis and the length (or width) of the minor axis.

Since the content of the titanium oxide particles directly affects the concentration of the titanium oxide dispersion and affects the storage stability, viscosity, pH, etc. of the cosmetic composition described later, these points are taken into consideration. And set as appropriate. Usually, it is preferably in the range of 10% by mass to 70% by mass, more preferably in the range of 20% by mass to 50% by mass, and in the range of 30% by mass to 40% by mass with respect to the total mass of the titanium oxide dispersion. More preferred. By setting the content of the titanium oxide dispersion to 20% by mass or more, the ultraviolet shielding function of the titanium oxide particles can be satisfactorily maintained. On the other hand, by setting the content of the titanium oxide particles to 50% by mass or less, it is possible to prevent the titanium oxide particles from settling.

In the titanium oxide dispersion, sodium polyacrylate functions as a dispersant for titanium oxide particles. By blending sodium polyacrylate, the dispersibility of titanium oxide particles can be improved. In addition, sodium polyacrylate conforms to the standards stipulated by the Pharmaceutical Affairs Law and the like. Therefore, by using sodium polyacrylate as a dispersant, the biotoxicity of the titanium oxide dispersion can be reduced.

The content ratio of the titanium oxide particles of the present embodiment to sodium polyacrylate is preferably 1: 0.01 to 1: 0.5 on a mass basis, and 1: 0.02 to 1: 0.2. Is more preferable. By setting the content ratio to 1: 0.01 or more, it is possible to prevent a decrease in the dispersibility of the titanium oxide particles. On the other hand, by setting the content ratio to 1: 0.5 or less, it is possible to prevent a decrease in the dispersion stability of the titanium oxide particles.

Note that sodium polyacrylate is relatively less likely to generate bubbles when added to a dispersion medium described later, for example, as compared with other conventional dispersants. Therefore, in the titanium oxide dispersion of the present embodiment, the addition of the defoaming agent can be omitted.

Other matters of sodium polyacrylate are the same as those described when explaining the zinc oxide dispersion. Therefore, the detailed description thereof will be omitted.

The titanium oxide dispersion according to the present embodiment contains a dispersion medium for dispersing titanium oxide particles, and the dispersion medium is composed only of water and 1,3-butylene glycol and / or glycerin. A mixed solvent is used.

As the water, the same water as that used in the zinc oxide dispersion can be used. Therefore, the detailed description thereof will be omitted.

The compounding ratio of 1,3-butylene glycol to the dispersion medium (1,3-butylene glycol / dispersion medium) is in the range of 0.1 / 1 to 0.9 / 1 on a mass basis, and is preferably 0.2. It is 1/1 to 0.9 / 1, more preferably 0.4 / 1 to 0.9 / 1. The compounding ratio of glycerin to the dispersion medium (glycerin / dispersion medium) is in the range of 0.1 / 1 to 0.9 / 1 on a mass basis, and is preferably 0.2 / 1 to 0.9 / 1. , More preferably 0.3 / 1 to 0.9 / 1. Polyacrylic acid adsorbed on the surface of titanium oxide particles by setting the blending ratio of 1,3-butylene glycol to the dispersion medium to 0.1 / 1 or more and the blending ratio of glycerin to the dispersion medium of 0.1 / 1 or more. The wettability of sodium acid to a dispersion medium can be improved. As a result, the titanium oxide particles on which sodium polyacrylate is adsorbed are wetted, and the decrease in cohesive force is promoted. As a result, reaggregation due to overdispersion of the titanium oxide particles can be suppressed or reduced, and the value of the dispersed particle diameter D99 of the titanium oxide particles can be prevented from increasing. On the other hand, the viscosity of the titanium oxide dispersion is increased by setting the blending ratio of 1,3-butylene glycol to the dispersion medium to 0.9 / 1 or less and the blending ratio of glycerin to the dispersion medium to 0.9 / 1 or less. It can be prevented from becoming too large.

The content of the dispersion medium is preferably in the range of 29% by mass to 89% by mass, more preferably in the range of 50% by mass to 80% by mass, and 60% by mass to 70% by mass with respect to the total mass of the titanium oxide dispersion. The range of% is particularly preferable.

The average dispersed particle size D10 of the dispersed titanium oxide particles is preferably in the range of 5 nm to 100 nm, and more preferably in the range of 10 nm to 60 nm. The average dispersed particle size D50 of the titanium oxide particles is preferably in the range of 20 nm to 500 nm, more preferably in the range of 40 nm to 100 nm. Further, the average dispersed particle size D99 of the titanium oxide particles is preferably 350 nm or less, more preferably 30 nm to 300 nm, and particularly preferably 50 nm to 200 nm. By setting D10 to 5 nm or more or D50 to 20 nm or more, deterioration of the storage stability of the titanium oxide dispersion can be prevented. On the other hand, by setting D10 to 100 nm or less, D50 to 500 nm or less, or D99 to 350 nm or less, separation, sedimentation and aggregation of titanium oxide particles can be prevented, and the storage stability of the titanium oxide dispersion can be maintained. The average dispersed particle diameters D10, D50 and D99 of the titanium oxide particles are values measured by a dynamic light scattering method using Microtrac UPA-EX150 (trade name, manufactured by Nikkiso Co., Ltd.).

The titanium oxide dispersion of the present embodiment can be produced by the same method as the zinc oxide dispersion. Therefore, the detailed description thereof will be omitted.

(Cosmetic composition)
The zinc oxide dispersion and the titanium oxide dispersion of the present embodiment can all be composed of components conforming to the standards of the Pharmaceutical Affairs Law and the like, and have low biotoxicity. Therefore, the zinc oxide dispersion or the titanium oxide dispersion of the present embodiment (hereinafter, referred to as “zinc oxide dispersion or the like”) can be contained in, for example, a cosmetic composition and used. Specifically, since the zinc oxide particles and the titanium oxide particles also function as an ultraviolet shielding agent, the zinc oxide dispersion or the like of the present embodiment is blended into a cosmetic composition having an O / W (Oil in Water) formulation. Can be done.

The cosmetic composition of the present embodiment may contain other additives as needed, in addition to the zinc oxide dispersion and the like. Other additives that can be incorporated into cosmetic compositions are not particularly limited, and examples thereof include moisturizers, plasticizers, silicones, mineral fillers, clays, preservatives, and fragrances. These additives may be used alone or in combination of two or more.

The content of the additive is not particularly limited and can be appropriately set as needed.

The cosmetic composition of the present embodiment can be applied to a sunscreen or the like. Further, in the cosmetic composition of the present embodiment, the values of the average dispersed particle diameters D10, D50 and D99 of the zinc oxide particles and the titanium oxide particles (hereinafter referred to as "zinc oxide particles and the like") are small, and the zinc oxide is zinc oxide. Since it has excellent dispersibility of particles and the like, even if the cosmetic composition is applied on the skin, it is possible to suppress or reduce the occurrence of the so-called whitening phenomenon in which a white film remains on the skin during and after application. can. Further, even when the cosmetic composition is allowed to stand for a certain period of time, the separation, sedimentation and aggregation of the zinc oxide particles and the like can be reduced or prevented.

Hereinafter, preferred embodiments of the present invention will be described in detail by way of example. However, the materials, contents, etc. described in the following examples are not limited to those of the present invention unless otherwise specified.

(Example 1-1)
First, a mixed solvent consisting of zinc oxide nanoparticles, sodium polyacrylate as a dispersant, pure water as a dispersion medium and propylene glycol ((propylene glycol / dispersion medium) = 0.63 / 1) was placed in a container. The blending ratio of these materials was as shown in Table 1. Zirconia beads were also put into the container, and zinc oxide nanoparticles were dispersed at room temperature using a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.). The dispersion time (shaking time by the disperser) was 72 hours. As a result, the zinc oxide dispersion according to this example was prepared.

Further, in the produced zinc oxide dispersion, the average dispersed particle diameters D10, D50 and D99 of the zinc oxide nanoparticles were measured, respectively. The results are shown in Table 1. Unless otherwise specified, the numerical values in Table 1 are expressed in mass% with respect to the total mass of the zinc oxide dispersion.

As the zinc oxide nanoparticles, FINEX-50 (trade name, average primary particle diameter of about 20 nm, no surface treatment) manufactured by Sakai Chemical Industry Co., Ltd. was used. As the dispersant sodium polyacrylate, TEGO Dispers 715W (mass average molecular weight 3000) manufactured by Evonik was used.

(Example 1-2)
In Example 1-2, a mixed solvent composed of pure water and glycerin ((glycerin / dispersion medium) = 0.63 / 1) was used as the dispersion medium. Other than that, as in Example 1-1, put each material in a container so that the blending ratio is as shown in Table 1, and use a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.) for 72 hours at room temperature. (Dispersion time) Dispersion processing was performed. As a result, the zinc oxide dispersion according to this example was prepared.

Further, in the same manner as in Example 1-1, the average dispersed particle diameters D10, D50 and D99 of the zinc oxide nanoparticles in the produced zinc oxide dispersion were measured, respectively. The results are shown in Table 1.

(Comparative Example 1-1)
In Comparative Example 1-1, only pure water was used as the dispersion medium. Other than that, as in Example 1, each material is placed in a container so that the blending ratio is as shown in Table 1, and a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.) is used at room temperature for 72 hours (dispersion). Time) Distributed processing was performed. As a result, the zinc oxide dispersion according to this comparative example was prepared.

(Comparative Example 1-2)
In Comparative Example 1-2, a mixed solvent composed of pure water and 1,3-butylene glycol ((1,3-butylene glycol / dispersion medium) = 0.63 / 1) was used as the dispersion medium. Other than that, as in Example 1-1, put each material in a container so that the blending ratio is as shown in Table 1, and use a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.) for 72 hours at room temperature. Dispersion processing of (dispersion time) was performed. However, the zinc oxide nanoparticles could not be dispersed in the mixed solvent. The results are shown in Table 1.

(Comparative Example 1-3)
In Comparative Example 1-3, a mixed solvent composed of pure water and dipropylene glycol ((dipropylene glycol / dispersion medium) = 0.63 / 1) was used as the dispersion medium. Other than that, as in Example 1-1, put each material in a container so that the blending ratio is as shown in Table 1, and use a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.) for 72 hours at room temperature. Dispersion processing of (dispersion time) was performed. However, the zinc oxide nanoparticles could not be dispersed in the mixed solvent. The results are shown in Table 1.

(Comparative Example 1-4)
In Comparative Example 1-4, a mixed solvent composed of pure water and polyethylene glycol 200 ((polyethylene glycol 200 / dispersion medium) = 0.63 / 1) was used as the dispersion medium. Other than that, as in Example 1-1, put each material in a container so that the blending ratio is as shown in Table 1, and use a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.) for 72 hours at room temperature. Dispersion processing of (dispersion time) was performed. However, the zinc oxide nanoparticles could not be dispersed in the mixed solvent. The results are shown in Table 1.

(Comparative Example 1-5)
In Comparative Example 1-5, a mixed solvent composed of pure water and ethanol ((ethanol / dispersion medium) = 0.63 / 1) was used as the dispersion medium. Other than that, as in Example 1-1, put each material in a container so that the blending ratio is as shown in Table 1, and use a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.) for 72 hours at room temperature. Dispersion processing of (dispersion time) was performed. However, the zinc oxide nanoparticles could not be dispersed in the mixed solvent. The results are shown in Table 1.

(Examples 1-3 to 1-6)
In Examples 1-3 to 1-6, the compounding ratio of propylene glycol and pure water (propylene glycol / dispersion medium) in the dispersion medium was changed as shown in Table 2, respectively. Other than that, the zinc oxide dispersion according to each example was prepared in the same manner as in Example 1-1.

Further, in the same manner as in Example 1-1, the average dispersed particle diameters D10, D50 and D99 of the zinc oxide nanoparticles in the produced zinc oxide dispersions of each example were measured. The results are shown in Table 2.

(Comparative Examples 1-6 to 1-8)
In Comparative Examples 1-6 to 1-8, the compounding ratio of propylene glycol and pure water (propylene glycol / dispersion medium) in the dispersion medium was changed as shown in Table 2. Other than that, the zinc oxide dispersion according to each Comparative Example was prepared in the same manner as in Example 1-1. However, in Comparative Example 1-8, the zinc oxide nanoparticles could not be dispersed in the mixed solvent.

Further, in the same manner as in Example 1-1, the average dispersed particle diameters D10, D50 and D99 of the zinc oxide nanoparticles in the prepared zinc oxide dispersions of Comparative Examples 1-6 and 1-7 were measured, respectively. The results are shown in Table 2.

(Examples 1-7 to 1-12)
In Examples 1-7 to 1-12, the compounding ratio of glycerin and pure water (glycerin / dispersion medium) in the dispersion medium was changed as shown in Table 3. Other than that, the zinc oxide dispersion according to each example was prepared in the same manner as in Example 1-2.

Further, in the same manner as in Example 1-2, the average dispersed particle diameters D10, D50 and D99 of the zinc oxide nanoparticles in the produced zinc oxide dispersions of each example were measured. The results are shown in Table 3.

(Comparative Example 1-9)
In Comparative Example 1-9, the compounding ratio of glycerin and pure water (glycerin / dispersion medium) in the dispersion medium was changed to 0.98 / 1. Other than that, the zinc oxide nanoparticles were dispersed in the same manner as in Example 1-2, but the zinc oxide nanoparticles could not be dispersed in the mixed solvent. The results are shown in Table 3.

(Example 2-1)
First, a mixed solvent consisting of titanium oxide nanoparticles, sodium polyacrylate as a dispersant, pure water as a dispersion medium, and glycerin ((glycerin / dispersion medium) = 0.63 / 1) was placed in a container. The blending ratios of these materials were as shown in Table 4. Zirconia beads were also put into the container, and the titanium oxide nanoparticles were dispersed at room temperature using a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.). The dispersion time (shaking time by the disperser) was 96 hours. As a result, the titanium oxide dispersion according to this example was prepared.

Further, in the produced titanium oxide dispersion, the average dispersed particle diameters D10, D50 and D99 of the titanium oxide nanoparticles were measured, respectively. The results are shown in Table 4. Unless otherwise specified, the numerical values in Table 4 are expressed in mass% with respect to the total mass of the titanium oxide dispersion.

As the titanium oxide nanoparticles, STR40N (trade name, average primary particle diameter of about 40 nm, no surface treatment) manufactured by Sakai Chemical Industry Co., Ltd. was used. As the dispersant sodium polyacrylate, TEGO Dispers 715W (mass average molecular weight 3000) manufactured by Evonik was used.

(Example 2-2)
In Example 2-2, a mixed solvent composed of pure water and 1,3-butylene glycol ((1,3-butylene glycol / dispersion medium) = 0.63 / 1) was used as the dispersion medium. Other than that, as in Example 2-1, put each material in a container so that the blending ratio is as shown in Table 4, and use a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.) for 96 hours at room temperature. (Dispersion time) Dispersion processing was performed. As a result, the titanium oxide dispersion according to this example was prepared.

Further, in the same manner as in Example 2-1 the average dispersed particle diameters D10, D50 and D99 of the titanium oxide nanoparticles in the produced titanium oxide dispersion were measured. The results are shown in Table 4.

(Comparative Example 2-1)
In Comparative Example 2-1 only pure water was used as the dispersion medium. Other than that, as in Example 2-1, put each material in a container so that the blending ratio is as shown in Table 4, and use a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.) for 96 hours at room temperature. (Dispersion time) Dispersion processing was performed. As a result, the titanium oxide dispersion according to this comparative example was prepared.

(Comparative Example 2-2)
In Comparative Example 2-2, a mixed solvent composed of pure water and dipropylene glycol ((dipropylene glycol / dispersion medium) = 0.63 / 1) was used as the dispersion medium. Other than that, as in Example 2-1, put each material in a container so that the blending ratio is as shown in Table 4, and use a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.) for 96 hours at room temperature. Dispersion processing of (dispersion time) was performed. However, the titanium oxide nanoparticles could not be dispersed in the mixed solvent. The results are shown in Table 4.

(Comparative Example 2-3)
In Comparative Example 2-3, a mixed solvent composed of pure water and polyethylene glycol 200 ((polyethylene glycol 200 / dispersion medium) = 0.63 / 1) was used as the dispersion medium. Other than that, as in Example 2-1, put each material in a container so that the blending ratio is as shown in Table 4, and use a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.) for 96 hours at room temperature. Dispersion processing of (dispersion time) was performed. However, the titanium oxide nanoparticles could not be dispersed in the mixed solvent. The results are shown in Table 4.

(Comparative Example 2-4)
In Comparative Example 2-4, a mixed solvent composed of pure water and ethanol ((ethanol / dispersion medium) = 0.63 / 1) was used as the dispersion medium. Other than that, as in Example 2-1, put each material in a container so that the blending ratio is as shown in Table 4, and use a disperser (paint shaker, manufactured by Asada Iron Works Co., Ltd.) for 96 hours at room temperature. Dispersion processing of (dispersion time) was performed. However, the titanium oxide nanoparticles could not be dispersed in the mixed solvent. The results are shown in Table 4.

(Examples 2-3 to 2-8)
In Examples 2-3 to 2-8, the compounding ratio of 1,3-butylene glycol and pure water (1,3-butylene glycol / dispersion medium) in the dispersion medium is as shown in Table 5, respectively. changed. Other than that, the titanium oxide dispersion according to each example was prepared in the same manner as in Example 2-1.

Further, in the same manner as in Example 2-1 the average dispersed particle diameters D10, D50 and D99 of the titanium oxide nanoparticles in the prepared titanium oxide dispersion of each example were measured. The results are shown in Table 5.

(Comparative Example 2-5)
In Comparative Example 2-5, the compounding ratio of 1,3-butylene glycol and pure water (1,3-butylene glycol / dispersion medium) in the dispersion medium was changed to 0.98 / 1. Other than that, the titanium oxide nanoparticles were dispersed in the same manner as in Example 2-1 but the titanium oxide nanoparticles could not be dispersed in the mixed solvent. The results are shown in Table 5.

(Examples 2-9 to 2-14)
In Examples 2-9 to 2-14, the compounding ratio of glycerin and pure water (glycerin / dispersion medium) in the dispersion medium was changed as shown in Table 6. Other than that, the titanium oxide dispersion according to each example was prepared in the same manner as in Example 2-2.

Further, in the same manner as in Example 2-2, the average dispersed particle diameters D10, D50 and D99 of the titanium oxide nanoparticles in the prepared titanium oxide dispersion of each example were measured. The results are shown in Table 6.

(Comparative Example 2-6)
In Comparative Example 2-6, the mixing ratio of glycerin and pure water (glycerin / dispersion medium) in the dispersion medium was changed as shown in Table 6. Other than that, the titanium oxide nanoparticles were dispersed in the same manner as in Example 2-2, but the titanium oxide nanoparticles could not be dispersed in the mixed solvent. The results are shown in Table 6.

(Measurement of mass average molecular weight of sodium polyacrylate)
The mass average molecular weight of sodium polyacrylate is a value obtained by gel permeation chromatography (GPC) using polyethylene oxide (PEO) / polyethylene glycol (PEG) as a standard product.

(Measurement of average primary particle size and average dispersed particle size of zinc oxide nanoparticles and titanium oxide nanoparticles)
The average primary particle diameters of the zinc oxide nanoparticles and the titanium oxide nanoparticles and the average dispersed particle diameters D10, D50 and D99 in each Example and Comparative Example are Microtrack UPA-EX150 (trade name, manufactured by Nikkiso Co., Ltd.). Was measured by the dynamic light scattering method.

Further, based on the measured average dispersed particle diameters D50 and D99 of the zinc oxide nanoparticles, the dispersibility was evaluated according to the following criteria. The results are shown in Tables 1 to 3.
⊚: D50 <60 nm and D99 <200 nm
○: When none of the conditions of ◎, △ and × is met Δ: D50> 100 nm or D99> 300 nm
×: Not dispersed

Furthermore, based on the measured average dispersed particle diameters D50 and D99 of the titanium oxide nanoparticles, the dispersibility was evaluated according to the following criteria. The results are shown in Tables 4 to 6.
⊚: D50 <80 nm and D99 <200 nm
○: When none of the conditions of ◎, △ and × is met Δ: D50> 100 nm or D99> 300 nm
×: Not dispersed

(result)
As can be seen from the experimental results of Examples 1-1 and 1-2 shown in Table 1, when a mixed solvent consisting only of pure water and propylene glycol or glycerin was used as the dispersion medium, the zinc oxide nanoparticles D10, D50 and All of the values of D99 could be satisfactorily reduced. In particular, it was found that the value of the zinc oxide nanoparticles D50 could be less than 60 nm and the value of D99 could be less than 200 nm, and that propylene glycol and glycerin contributed to the improvement of the dispersibility of the zinc oxide nanoparticles. On the other hand, when the dispersion medium is pure water as in Comparative Example 1-1, zinc oxide nanoparticles can be dispersed, but the value of D99 exceeds 300 nm. Further, in the case of Comparative Examples 1-2 to 1-5 in which a mixed solvent consisting only of pure water and an organic solvent other than propylene glycol and glycerin was used as the dispersion medium, the zinc oxide nanoparticles were dispersed in the mixed solvent. I couldn't get it.

Further, as can be seen from the experimental results of Examples 1-3 to 1-6 shown in Table 2, a mixed solvent consisting only of pure water and propylene glycol was used as the dispersion medium, and the blending ratio of propylene glycol was used as the dispersion medium. On the other hand, the value of D99 could be sufficiently reduced by setting it in the range of 0.13 / 1 to 0.89 / 1. As a result, it was confirmed that the zinc oxide dispersions of Examples 1-3 to 1-6 can effectively suppress the overdispersed zinc oxide nanoparticles from becoming coarse particles due to reaggregation.

Further, as can be seen from the experimental results of Examples 1-7 to 1-12 shown in Table 3, a mixed solvent consisting only of pure water and glycerin is used as the dispersion medium, and the blending ratio of glycerin is 0 with respect to the dispersion medium. Even when the value was within the range of .13/1 to 0.89/1, the value of D99 could be sufficiently reduced. As a result, it was confirmed that even in the zinc oxide dispersions of Examples 1-3 to 1-6, the overdispersed zinc oxide nanoparticles can be effectively suppressed from becoming coarse particles due to reaggregation.

As can be seen from the experimental results of Examples 2-1 and 2-2 shown in Table 4, when a mixed solvent consisting only of pure water and 1,3-butylene glycol or glycerin was used as the dispersion medium, D10 of titanium oxide nanoparticles was used. , D50 and D99 could all be satisfactorily reduced. In particular, it was found that the value of the titanium oxide nanoparticles D50 could be less than 80 nm and the value of D99 could be less than 200 nm, and that 1,3-butylene glycol and glycerin contributed to the improvement of the dispersibility of the titanium oxide nanoparticles. .. On the other hand, when the dispersion medium is pure water as in Comparative Example 2-1 the titanium oxide nanoparticles can be dispersed, but the value of D99 exceeds 300 nm. Further, in the case of Comparative Examples 2-2 to 2-4 in which a mixed solvent consisting only of pure water and an organic solvent other than 1,3-butylene glycol and glycerin was used as the dispersion medium, titanium oxide nanoparticles were mixed as the mixed solvent. Could not be dispersed inside.

Further, as can be seen from the experimental results of Examples 2-3 to 2-8 shown in Table 5, a mixed solvent consisting only of pure water and 1,3-butylene glycol was used as the dispersion medium, and 1,3-butylene was used. By setting the blending ratio of glycol in the range of 0.13 / 1 to 0.89 / 1 with respect to the dispersion medium, the value of D99 could be sufficiently reduced. As a result, it was confirmed that the titanium oxide dispersions of Examples 2-3 to 2-8 can effectively suppress the overdispersed titanium oxide nanoparticles from becoming coarse particles due to reaggregation.

Further, as can be seen from the experimental results of Examples 2-9 to 2-14 shown in Table 6, a mixed solvent consisting only of pure water and glycerin is used as the dispersion medium, and the blending ratio of glycerin is 0 with respect to the dispersion medium. Even when the value was within the range of .13/1 to 0.89/1, the value of D99 could be sufficiently reduced. As a result, it was confirmed that even in the titanium oxide dispersions of Examples 2-9 to 2-14, it was possible to effectively suppress the overdispersed titanium oxide nanoparticles from becoming coarse particles due to reaggregation.

Claims

With zinc oxide particles,
The dispersant of the zinc oxide particles made of sodium polyacrylate having a mass average molecular weight of less than 10,000, and the dispersant.
It contains a dispersion medium for dispersing the zinc oxide particles.
The dispersion medium consists only of water and propylene glycol and / or glycerin.
The compounding ratio of the propylene glycol to the dispersion medium (propylene glycol / dispersion medium) is in the range of 0.3 / 1 to 0.9 / 1 on a mass basis.
A zinc oxide dispersion in which the compounding ratio of the glycerin to the dispersion medium (glycerin / dispersion medium) is in the range of 0.1 / 1 to 0.8 / 1 on a mass basis.
The zinc oxide dispersion according to claim 1, wherein the zinc oxide particles are zinc oxide particles that have not been surface-treated.
The zinc oxide dispersion according to claim 1 or 2, wherein the content ratio of the zinc oxide particles to the sodium polyacrylate is in the range of 1: 0.01 to 1: 0.5 on a mass basis.
The zinc oxide dispersion according to any one of claims 1 to 3, wherein the dispersed zinc oxide particles have an average dispersed particle diameter D99 of 350 nm or less.
Titanium oxide particles and
The dispersant of the titanium oxide particles made of sodium polyacrylate having a mass average molecular weight of less than 10,000, and the dispersant.
A dispersion medium for dispersing the titanium oxide particles is included.
The dispersion medium consists only of water and 1,3-butylene glycol and / or glycerin.
The compounding ratio of the 1,3-butylene glycol to the dispersion medium (1,3-butylene glycol / dispersion medium) is in the range of 0.1 / 1 to 0.9 / 1 on a mass basis.
A titanium oxide dispersion in which the compounding ratio of the glycerin to the dispersion medium (glycerin / dispersion medium) is in the range of 0.1 / 1 to 0.9 / 1 on a mass basis.
The titanium oxide dispersion according to claim 5, wherein the titanium oxide particles are titanium oxide particles that have not been surface-treated.
The titanium oxide dispersion according to claim 5 or 6, wherein the content ratio of the titanium oxide particles to the sodium polyacrylate is in the range of 1: 0.01 to 1: 0.5 on a mass basis.
The titanium oxide dispersion according to any one of claims 5 to 7, wherein the dispersed average dispersed particle diameter D99 of the dispersed titanium oxide particles is 350 nm or less.
A cosmetic composition containing the zinc oxide dispersion according to any one of claims 1 to 4 or the titanium oxide dispersion according to any one of claims 5 to 8.