Hydrophobic silica particles and their uses, and method for producing hydrophobic silica particles

Abstract

The present invention provides a novel particulate material which is composed of particles that are configured from naturally derived starting materials, and which is able to be stably dispersed in an oil phase. Hydrophobic silica particles according to the present invention are obtained by having silica particles support a higher alcohol that has 19 or more carbon atoms; and the degree of bonding of the higher alcohol to the silica particles is 70% or more, said degree of bonding being expressed by the ratio of the carbon content in the hydrophobic silica particles after cleaning to the carbon content in the hydrophobic silica particles before cleaning if a filtration residue, which is obtained by dispersing 1 g of the hydrophobic silica particles in 10 mL of tetrahydrofuran and subsequently filtering the dispersion after maintaining the dispersed state for 5 minutes, is cleaned with 20 mL of tetrahydrofuran and 20 mL of hexane, and is dried thereafter.

Description

[Technical Field]

[0001] This invention relates to hydrophobic silica particles, their uses, and a method for producing hydrophobic silica particles. [Background technology]

[0002] Particulate materials are used as fillers and other materials in various fields. For example, in the cosmetics field, spherical fine particle powders are incorporated into cosmetics to improve the slipperiness and feel of cosmetics on the skin, to cover skin blemishes, freckles, acne, etc., and to improve skin tone and makeup effects.

[0003] Fine particle powders made from synthetic resins such as urethane, silicone, nylon, acrylic, polystyrene, and polyethylene have a good feel and are therefore widely used in powder cosmetics such as foundations and body powders. On the other hand, microplastic beads, which are made by micronizing synthetic resins, are lightweight, difficult to decompose, and hydrophobic. As a result, they are easily released into the environment without being adequately removed in sewage treatment facilities, are easily ingested by marine organisms, and are prone to bioaccumulation. Furthermore, because they readily adsorb hydrophobic harmful substances, they facilitate the introduction of harmful substances into the food chain. In recent years, concerns have been raised about the impact of such microplastic beads on the natural environment, and efforts are being made worldwide to reduce the amount of microplastics generated.

[0004] Therefore, fine particle powders made from inorganic materials such as talc, mica, kaolin, silica, calcium carbonate, and aluminum oxide are attracting attention. Because fine particle powders made from inorganic materials have an inferior feel to fine particle powders made from synthetic resins when they come into contact with the skin, efforts are made to improve the feel by modifying the surface of the fine particles. For example, inorganic materials are coated with silicone or silylation agents.

[0005] However, due to the recent trend towards natural products, there is a demand for naturally derived particles that do not contain silicones, and various studies are being conducted. For example, Patent Document 1 describes adding a higher alcohol to a solvent phase in which porous silica particles are dispersed, drying it under vacuum, and modifying the surface of the porous silica particles to be hydrophobic through a condensation reaction between the hydrophilic groups of the porous silica particles and the higher alcohol. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2018 / 182107 [Overview of the project] [Problems that the invention aims to solve]

[0007] The hydrophobic porous silica particles described in Patent Document 1 are said to have more than 90% of their surface modified to be hydrophobic, and to have excellent water repellency and oil absorption properties. However, the hydrophobic porous silica particles described in Patent Document 1 have a weak binding force to higher alcohols, and the higher alcohols tend to detach easily in oil, making it difficult to maintain hydrophobicity.

[0008] The present invention has been made in view of the above problems, and aims to provide a new particulate material which is composed of naturally derived raw materials, has high hydrophobicity, and can be stably dispersed in an oil phase. [Means for solving the problem]

[0009] As a result of diligent research, the inventors of the present invention discovered that the above problem can be solved by hydrophobic silica particles in which a higher alcohol having 19 or more carbon atoms is supported, and in which the degree of bonding of the higher alcohol is 70% or higher as measured by bonding degree measurement, thus completing the present invention.

[0010] The present invention relates to the following <1> ~ <10> This concerns... <1>Silica particles are loaded with a higher alcohol having 19 or more carbon atoms, and the degree of binding of the higher alcohol to the silica particles measured by the following measurement method is 70% or more. Measurement method: 1 g of hydrophobic silica particles is dispersed in 10 mL of tetrahydrofuran, and after maintaining the dispersed state for 5 minutes, the residue obtained by filtration is washed with 20 mL of tetrahydrofuran and 20 mL of hexane and dried. The ratio of the carbon content of the hydrophobic silica particles after washing to the carbon content of the hydrophobic silica particles before washing represented by the following formula (1) is defined as the degree of binding. Degree of binding (%) = Carbon content (%) of hydrophobic silica particles after washing / Carbon content (%) of hydrophobic silica particles before washing × 100 ··· (1) <2>The loading amount of the higher alcohol is 1.0 μmol / m 2 or more, the hydrophobic silica particles according to <1> above. <3>The roundness is 0.95 or more, the hydrophobic silica particles according to <1> or <2> above. <4>The average particle diameter of the hydrophobic silica particles is 1 to 500 μm, the hydrophobic silica particles according to any one of <1> to <3> above. <5>The specific surface area of the silica particles as the base material is 5 to 1000 m 2 / g, the hydrophobic silica particles according to any one of <1> to <4> above. <6>The oil absorption amount is 20 mL / 100 g or more, the hydrophobic silica particles according to any one of <1> to <5> above. <7>The degree of binding is 80% or more, the hydrophobic silica particles according to any one of <1> to <6> above. <8>A cosmetic containing the hydrophobic silica particles according to any one of <1> to <7> above. <9>A method for producing hydrophobic silica particles, comprising heating silica particles to which a higher alcohol having 14 or more carbon atoms is attached at 160 °C or higher. <10>A method for producing the hydrophobic silica particles according to <9> above, comprising heating and mixing a higher alcohol having 14 or more carbon atoms and silica particles without substantially using a solvent to obtain silica particles to which the higher alcohol having 14 or more carbon atoms is attached.

Effect of the Invention

[0011] Since the hydrophobic silica particles of the present invention have a high binding force for higher alcohols, hydrophobicity is maintained and stability in oil is improved. Therefore, stable water repellency can be maintained. In addition, since the hydrophobic silica particles of the present invention are composed of naturally derived raw materials, they have the effect of being friendly to the environment and the human body. Moreover, when applied to the skin, they can impart a smooth and slippery feeling (powdery feeling). Therefore, they can be suitably used in skin compositions such as cosmetics, oral compositions, adsorbent compositions, pharmaceutical compositions, and the like.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described, but the present invention is not limited by the examples in the following description. In the present invention, "supported" means a state in which a higher alcohol is bonded to the surface and / or the inner surface of pores of silica particles. Also, in this specification, "mass" is synonymous with "weight".

[0013] (Hydrophobic silica particles) The hydrophobic silica particles of the present invention are those in which a higher alcohol having 19 or more carbon atoms is supported on silica particles, and the degree of binding of the higher alcohol to the silica particles measured by the following measurement method is 70% or more. Measurement method: 1 g of hydrophobic silica particles is dispersed in 10 mL of tetrahydrofuran, and after maintaining the dispersed state for 5 minutes, the residue obtained by filtration is washed with 20 mL of tetrahydrofuran and 20 mL of hexane and dried. The ratio of the carbon content of the hydrophobic silica particles after washing to the carbon content of the hydrophobic silica particles before washing represented by the following formula (1) is defined as the degree of binding. Degree of binding (%) = Carbon content (%) of hydrophobic silica particles after washing / Carbon content (%) of hydrophobic silica particles before washing × 100 ··· (1) That is, the "degree of binding" indicates the remaining amount of the higher alcohol having 19 or more carbon atoms remaining in the hydrophobic silica particles after washing when the hydrophobic silica particles are washed by the above method.

[0014] Here, the carbon content of hydrophobic silica particles can be measured using an elemental analyzer (for example, PerkinElmer's "CHN-2400").

[0015] When the degree of bonding of higher alcohols with 19 or more carbon atoms to silica particles, which serve as the base material, is 70% or higher, the stability of the hydrophobic silica particles in oil is improved, and the dispersed state can be maintained. The degree of bonding is 70% or more, preferably 75% or more, more preferably 80% or more, even more preferably 85% or more, and particularly preferably 90% or more. There is no particular upper limit to the degree of bonding, but 100% is most preferred.

[0016] Examples of higher alcohols with 19 or more carbon atoms that can be supported on silica particles include chimyl alcohol, arachidyl alcohol, octyldodecanol, ethylene glycol monostearate, monoethanolamide stearate, glycerol monostearate, cerakyl alcohol, batyl alcohol, behenyl alcohol, decyltetradecanol, and carnavir alcohol.

[0017] Higher alcohols with 19 or more carbon atoms are readily available industrially, and from the viewpoint of imparting sufficient water repellency to hydrophobic silica particles, higher alcohols with 19 to 36 carbon atoms are preferred. The carbon number of the higher alcohol is more preferably 30 or less, even more preferably 28 or less, and particularly preferably 24 or less.

[0018] Higher alcohols with 19 or more carbon atoms may be straight-chain or branched-chain, and may be saturated or unsaturated. For higher alcohols with 19 or more carbon atoms, the number of hydroxyl groups should be one or more. Practically speaking, five or fewer hydroxyl groups are preferable, and three or fewer are more preferable. In addition, the higher alcohol having 19 or more carbon atoms may have an unsaturated long-chain alkyl group and a hydroxyl group, provided that a linking group may be present between the unsaturated long-chain alkyl group (which may be unsaturated) and the hydroxyl group. Examples of the linking group include an ester bond, an ether oxygen atom, an amide bond, and the like.

[0019] The higher alcohol having 19 or more carbon atoms is more preferably at least one selected from the group consisting of chimyl alcohol, arachidyl alcohol, octyldodecanol, ethylene glycol monostearate, monoethanolamide stearate, glycerol monostearate, ceralkyl alcohol, batyl alcohol, behenyl alcohol, and decyltetradecanol.

[0020] In addition, the fact that the higher alcohol having 19 or more carbon atoms is supported on the surface of the silica particles can be confirmed from the chemical shift obtained by solid-state nuclear magnetic resonance measurement ( 13 C-NMR, CP / MAS method) of the hydrophobic silica particles, or from the mass chromatogram obtained by GC-MS measurement of the higher alcohol solution obtained by decomposing the hydrophobic silica particles with an alkaline aqueous solution or the like and performing solvent extraction.

[0021] In the hydrophobic silica particles of the present invention, the loading amount (loading density) of the higher alcohol having 19 or more carbon atoms is preferably 1.0 μmol / m 2 or more. When the loading amount of the higher alcohol having 19 or more carbon atoms is 1.0 μmol / m 2 or more, 20% or more of the surface silanols of the silica particles are covered with the higher alcohol, and the water repellency of the hydrophobic silica particles is improved. The loading amount of the higher alcohol having 19 or more carbon atoms is more preferably 1.2 μmol / m 2 or more, even more preferably 1.3 μmol / m 2 or more, and particularly preferably 1.5 μmol / m 2 or more. The upper limit is not particularly limited, but since the maximum density of the silanol groups present on the surface of the amorphous silica particles capable of binding to the higher alcohol is 6 μmol / m 2 Therefore, 6 μmol / m2 Preferably, it is 5 μmol / m² 2 The following is more preferable: 4.5 μmol / m² 2 The following are even more preferable.

[0022] Furthermore, the amount (density) of higher alcohols with 19 or more carbon atoms that can be supported can be calculated using the following formula, based on the carbon content measured by an elemental analyzer, the molecular weight of the higher alcohol, and the specific surface area of ​​the raw silica particles.

[0023]

number

[0024] The shape of the hydrophobic silica particles of the present invention is not particularly limited. The circularity of the hydrophobic silica particles is preferably 0.85 or higher, and more preferably 0.88 or higher. When the circularity is 0.85 or higher, the filling efficiency is improved when used as various fillers. Furthermore, when used in cosmetics, the shape is preferably a perfect sphere or nearly perfect sphere from the viewpoint of improving the feel when it comes into contact with the skin. When used in cosmetics, the circularity of the hydrophobic silica particles is preferably 0.95 or higher, more preferably 0.97 or higher, even more preferably 0.98 or higher, and particularly preferably 0.99 or higher from the viewpoint of improving the feel. When the circularity of the hydrophobic silica particles is 0.95 or higher, the feel when applied to the skin becomes smooth, making them suitable for use in cosmetics. There is no particular upper limit to the circularity, but it is most preferably 1.

[0025] The circularity of hydrophobic silica particles can be measured by scanning electron microscopy (SEM) observation. Using a scanning electron microscope (for example, the JSM-6701F field emission scanning electron microscope manufactured by JEOL Ltd.), the maximum diameter in the X-axis direction and the maximum diameter in the Y-axis direction of the particles are determined at 10,000x magnification. The diameter in the direction with the larger value is defined as the major axis, and the diameter in the direction with the smaller value is defined as the minor axis. Based on these values, the circularity can be calculated using the following formula. Circularity = short axis (μm) / long axis (μm)

[0026] The average particle size of the hydrophobic silica particles of the present invention is preferably 1 to 500 μm. If the average particle size is 1 μm or more, aggregation is suppressed and sufficient dispersibility in the composition is easily ensured, and if it is 500 μm or less, the feel when incorporated into the composition is improved. The average particle size is more preferably 2 μm or more, even more preferably 3 μm or more, even more preferably 300 μm or less, even more preferably 100 μm or less, and particularly preferably 25 μm or less.

[0027] The average particle size of hydrophobic silica particles can be measured by observation with a scanning electron microscope (for example, the JSM-6701F field emission scanning electron microscope manufactured by JEOL Ltd.). Hydrophobic silica particles are fixed to carbon tape and then coated with platinum (Pt), and images are taken using an acceleration voltage of 1 kV and an emission current of 10 μA. Thirty particles are randomly selected from the SEM images taken at 1000x magnification, and the average value of the X-axis constant direction diameter (Crumbein diameter) is taken as the average particle size.

[0028] The hydrophobic silica particles of the present invention may be porous or non-porous, but from the viewpoint of having a large oil absorption capacity and being able to absorb excess sebum when applied to the skin, they are preferably porous.

[0029] The porosity of hydrophobic silica particles depends on the specific surface area of ​​the raw silica particles used as the base material, and can be confirmed by measuring the specific surface area of ​​the raw silica particles.

[0030] The hydrophobic silica particles of the present invention preferably have an oil absorption capacity of 20 mL / 100 g or more. An oil absorption capacity of 20 mL / 100 g or more allows for easy absorption of sebum when applied to the skin, making them suitable for use in cosmetics. The oil absorption capacity of the hydrophobic silica particles is more preferably 22 mL / 100 g or more, even more preferably 25 mL / 100 g or more. While there is no particular upper limit, from the viewpoint of maintaining particle strength, it is preferably 500 mL / 100 g or less, more preferably 450 mL / 100 g or less, and even more preferably 400 mL / 100 g or less.

[0031] The amount of oil absorbed can be measured in accordance with JIS K 5101-13-1 (2004).

[0032] The hydrophobic silica particles of the present invention preferably have a dynamic friction coefficient of 0.75 or less. When the dynamic friction coefficient is 0.75 or less, the particles slide with low resistance, improving the feel when in contact with the skin, and thus providing a smooth, slippery sensation. The dynamic friction coefficient is more preferably 0.60 or less, even more preferably 0.50 or less, and particularly preferably 0.40 or less. The lower limit of the dynamic friction coefficient is not particularly limited, but it is preferably 0.05 or more, more preferably 0.10 or more, and even more preferably 0.15 or more.

[0033] Furthermore, the static friction coefficient of the hydrophobic silica particles of the present invention is preferably 0.75 or less. When the static friction coefficient is 0.75 or less, the particles begin to slide with low resistance, improving the feel when in contact with the skin. The static friction coefficient is more preferably 0.70 or less, even more preferably 0.65 or less, particularly preferably 0.60 or less, and most preferably 0.55 or less. The lower limit of the static friction coefficient is not particularly limited, but it is more preferably 0.01 or more, even more preferably 0.05 or more, and particularly preferably 0.10 or more.

[0034] The coefficient of dynamic friction can be measured using a static / dynamic friction measuring instrument (for example, "TL201Tt" (product name) manufactured by Trinity Labs). Specifically, a urethane artificial finger is used as the contact element, and artificial leather is used as the coating substrate. The amount of coating adhering to the artificial leather is 0.8 μL / cm³ per unit area. 2 Hydrophobic silica particles are coated in such a manner, and the friction coefficient is measured while operating with a load of 30 gf and a scanning distance of 40 mm. The average value in the range of 1,000 msec to 4,000 msec is taken as the dynamic friction coefficient. The static friction coefficient is determined by measuring the friction coefficient in the same manner as described above, and the maximum value in the range from 0 msec to 1,000 msec is taken as the static friction coefficient.

[0035] (Method for producing hydrophobic silica particles) The present invention also provides a method for producing hydrophobic silica particles. The hydrophobic silica particles of the present invention are obtained by heating silica particles to which a higher alcohol having 14 or more carbon atoms is attached at 160°C or higher. Through the above process, the silanol groups on the surface of the silica particles and the hydroxyl groups of higher alcohols with 14 or more carbon atoms undergo dehydration condensation to form covalent bonds, thereby strengthening the bond between the particle surface of the silica particles and the higher alcohols with 14 or more carbon atoms.

[0036] Silica particles to which higher alcohols with 14 or more carbon atoms are attached are obtained by mixing silica particles as a base material with higher alcohols with 14 or more carbon atoms. Here, "adhesion" can refer to chemical bonding, but primarily means physical bonding, such as adhesive bonding. Whether silica particles and higher alcohols with 14 or more carbon atoms are uniformly attached to and mixed with each other can be determined by comparing the circularity of the particles before and after mixing using a scanning electron microscope or similar device.

[0037] The silica particles used as raw materials may be porous or non-porous. Porous silica particles are secondary particles in which primary silicon dioxide particles aggregate to form a continuous network of fine pores.

[0038] The shape of the silica particles is not particularly limited. The circularity of the silica particles is preferably 0.85 or higher, and more preferably 0.88 or higher. When the circularity is 0.85 or higher, the filling efficiency is improved when the hydrophobic silica particles of the present invention are used as various fillers. Furthermore, when used in cosmetics, the shape is preferably a perfect sphere or nearly perfect sphere from the viewpoint of improving the feel when it comes into contact with the skin. When used in cosmetics, the circularity of the silica particles is preferably 0.95 or higher, more preferably 0.97 or higher, even more preferably 0.98 or higher, and particularly preferably 0.99 or higher. When the circularity of the silica particles is 0.95 or higher, it is easier to obtain hydrophobic silica particles with a circularity of 0.95 or higher. There is no particular upper limit to the circularity, but it is most preferably 1.

[0039] The method for measuring circularity is as described above.

[0040] The average particle size of the silica particles used as raw material is preferably 1 to 500 μm. If the average particle size is 1 μm or more, aggregation is suppressed and sufficient dispersibility in the composition is easily ensured, and if it is 500 μm or less, the feel when incorporated into the composition is improved. The average particle size is more preferably 2 μm or more, even more preferably 3 μm or more, even more preferably 300 μm or less, even more preferably 100 μm or less, and particularly preferably 25 μm or less.

[0041] The average particle diameter can be calculated by determining the average value of the diameter in a specific direction using SEM observation, similar to the measurement of the average particle diameter of hydrophobic silica particles described above.

[0042] The specific surface area of ​​the raw silica particles is 5 to 1000 m². 2 It is preferable that the specific surface area of ​​the silica particles is 5 m². 2 A specific surface area of ​​1000 m² or more indicates that there are sufficient silanol groups to bond higher alcohols with 14 or more carbon atoms. While a larger specific surface area of ​​silica particles allows for greater support of higher alcohols, excessively large specific surface areas increase the amount of higher alcohol used, leading to excessively high manufacturing costs. Therefore, a specific surface area of ​​1000 m² is considered ideal. 2 It is preferable that the amount is less than or equal to / g. The specific surface area is 5m². 2 It is preferable that it is 10m or more per gram. 2 More preferably 15m / g or more, 2 More preferably 800m 2 It is more preferable that it be less than / g, and 600m 2 A value of less than or equal to / g is particularly preferred.

[0043] The specific surface area can be calculated using the BET method by nitrogen adsorption.

[0044] The pore volume of the silica particles used as raw material is preferably 0 to 2.5 mL / g. A pore volume of 0 mL / g or more allows for the desired oil absorption, while a pore volume of 2.5 mL / g or less maintains the particle strength. A pore volume of 0.1 mL / g or more is more preferable, 0.15 mL / g or more is even more preferable, 0.2 mL / g or more is particularly preferable, and 2.5 mL / g or less is even more preferable, 2.2 mL / g or less is even more preferable, and 2.0 mL / g or less is particularly preferable.

[0045] Furthermore, the pore volume can be calculated using the BJH method by nitrogen adsorption.

[0046] Furthermore, the silica particles used as raw materials preferably have an oil absorption capacity of 20 mL / 100 g. If the oil absorption capacity is 20 mL / 100 g or more, it can absorb sebum when applied to the skin, making it suitable for use in cosmetics. The oil absorption capacity is more preferably 22 mL / 100 g or more, even more preferably 25 mL / 100 g or more, and although there is no particular upper limit, it is preferably 500 mL / 100 g or less, more preferably 450 mL / 100 g or less, and even more preferably 400 mL / 100 g or less.

[0047] The amount of oil absorbed can be measured in accordance with JIS K 5101-13-1 (2004).

[0048] Commercially available silica particles can be used, such as "Sunsphere NP-30," "Sunsphere L-51," "Sunsphere L-52," and "FB-82" manufactured by AGC SI-TEC Co., Ltd.

[0049] Examples of higher alcohols with 14 or more carbon atoms include myristyl alcohol, cetyl alcohol (cetanol), 2-hexyldecanol, stearyl alcohol, cetostearyl alcohol, oleyl alcohol, linoleyl alcohol, linolenyl alcohol, isostearyl alcohol, chymyl alcohol, arachidyl alcohol, octyldodecanol, ethylene glycol monostearate, monoethanolamide stearate, glycerol monostearate, cerakyl alcohol, batyl alcohol, behenyl alcohol, decyltetradecanol, and carnavir alcohol.

[0050] Higher alcohols with 14 or more carbon atoms are readily available industrially, and from the viewpoint of imparting water repellency to the silica particle surface, higher alcohols with 14 to 36 carbon atoms are preferred. The carbon number of the higher alcohol is more preferably 16 or more, even more preferably 18 or more, particularly preferably 19 or more, most preferably 20 or more, more preferably 30 or less, even more preferably 28 or less, and particularly preferably 24 or less.

[0051] The aforementioned higher alcohol may be in the form of a straight chain or a branched chain, and may be saturated or unsaturated. For higher alcohols with 14 or more carbon atoms, the number of hydroxyl groups should be one or more. Practically, five or fewer hydroxyl groups are preferable, and three or fewer are more preferable. Furthermore, higher alcohols having 14 or more carbon atoms may have an unsaturated long-chain alkyl group and a hydroxyl group. However, they may also have a linking group between the unsaturated long-chain alkyl group and the hydroxyl group. Examples of linking groups include ester bonds, etheric oxygen atoms, and amide bonds.

[0052] The higher alcohol having 14 or more carbon atoms is more preferably one or more selected from the group consisting of chymyl alcohol, arachidyl alcohol, octyldodecanol, ethylene glycol monostearate, monoethanolamide stearate, glycerol monostearate, cerakyl alcohol, batyl alcohol, behenyl alcohol, and decyltetradecanol.

[0053] In this invention, first, silica particles are mixed with a higher alcohol having 14 or more carbon atoms, and the higher alcohol having 14 or more carbon atoms is deposited on the surface of the silica particles (mixing step). Since higher alcohols with 14 or more carbon atoms are solid or viscous liquids at room temperature, it is preferable to dissolve or reduce the viscosity of the higher alcohols with 14 or more carbon atoms by heating them and then mix them with silica particles.

[0054] The reaction temperature and reaction time in the mixing process can be set as appropriate, as long as the higher alcohol with 14 or more carbon atoms melts and adheres to the silica particles.

[0055] The mixing ratio of silica particles to higher alcohols with 14 or more carbon atoms is such that the amount of higher alcohol with 14 or more carbon atoms loaded per unit area of ​​silica particles is 1 to 6 μmol / m². 2 It is preferable to mix them in such a way that the amount of higher alcohols with 14 or more carbon atoms is 1 μmol / m³. 2 If the above conditions are met, hydrophobic silica particles with sufficient hydrophobicity can be obtained. If too much higher alcohol with 14 or more carbon atoms is used, a large amount will remain without adhering to the silica particles, so the concentration should be 6 μmol / m². 2 The following is preferable: For higher alcohols with 14 or more carbon atoms, the supported amount per unit area of ​​silica particles is 1.2 mol / m². 2 It is more preferable to mix them to the above result, 1.5 μmol / m². 2 The above is even more preferable, and also 5 μmol / m² 2 It is more preferable that the following conditions apply: 4 μmol / m³ 2 The following are even more preferable.

[0056] In the present invention, it is preferable to attach higher alcohols having 14 or more carbon atoms to silica particles substantially without the use of a solvent. "Substantially without the use of a solvent" means that no solvent is intentionally added during the mixing process, and excludes cases where solvent contamination is unavoidable. Examples of solvents include water, methanol, ethanol, and propanol. The solvent is preferably present in an amount of 10% by mass or less, more preferably 5% by mass or less, and most preferably not present at all, relative to 100% by mass of the higher alcohol with 14 or more carbon atoms used as a raw material.

[0057] After a mixing process in which higher alcohols with 14 or more carbon atoms are attached to the surface of silica particles, the particles are heat-treated at a temperature of 160°C or higher to bond the higher alcohols with 14 or more carbon atoms to the surface of the silica particles (bonding process).

[0058] The bonding process may be carried out by continuing to heat the mixture to 160°C or higher without lowering the temperature after the mixing process is complete, or by using silica particles to which higher alcohols with 14 or more carbon atoms have been attached, after they have been allowed to return to room temperature.

[0059] The reaction temperature in the bonding step is 160°C or higher, more preferably 165°C or higher, and even more preferably 170°C or higher. Furthermore, there is no particular upper limit, but from the viewpoint of suppressing the thermal decomposition of the raw material, higher alcohols with 14 or more carbon atoms, it is preferably 300°C or lower, and more preferably 250°C or lower. Heating to over 160°C causes the silanol groups on the surface of silica particles to undergo dehydration condensation with the hydroxyl groups of higher alcohols with 14 or more carbon atoms, forming a covalent bond, thus increasing the degree of bonding between them.

[0060] The heating method can be any conventionally known method, such as heating using a heating device, including examples such as a Henschel mixer, double cone dryer, Nauter mixer, and vibrating dryer. The heating treatment is preferably carried out under an inert gas atmosphere or under reduced pressure.

[0061] The reaction time in the bonding process is preferably 2 to 8 hours. If the reaction time is 2 hours or more, the condensation reaction between silica particles and higher alcohols with 14 or more carbon atoms proceeds appropriately, and if it is 8 hours or less, production can be carried out with high productivity. The reaction time is preferably 2 hours or more, more preferably 3 hours or more, preferably 8 hours or less, and more preferably 7 hours or less.

[0062] After heating, allowing it to cool yields hydrophobic silica particles on which higher alcohols with 14 or more carbon atoms are supported.

[0063] (Applications of hydrophobic silica particles) The hydrophobic silica particles of the present invention are suitably used in, for example, skin compositions, oral compositions, adsorbent compositions, pharmaceutical compositions, and the like. Examples of skin compositions include cosmetics such as foundation, body powder, and lipstick; shampoos and conditioners; facial cleansers; and lotions. Specifically, using the hydrophobic silica particles of the present invention in cosmetics such as foundation, face color, loose powder, and concealer can impart softness and a moist feel. Furthermore, using them in lipstick, liquid foundation, cream, lotion, and lotion can prevent stickiness, improve dispersibility in oil-based formulations, and enhance storage stability. In shampoos and conditioners, they exhibit an adsorption and removal effect on oily dirt. Examples of oral compositions include powder toothpaste and toothpaste. Specifically, adding the hydrophobic silica particles of the present invention to these can provide a milder polishing effect. [Examples]

[0064] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the following description, common components are the same. Unless otherwise specified, "%" represents "mass%". Examples 1 to 22 are examples, and Examples 23 to 25 are comparative examples.

[0065] <Evaluation Method> The evaluations performed on the hydrophobic silica particles and the raw silica particles used to produce the hydrophobic silica particles in Examples 1-25 are shown below.

[0066] (Specific surface area and pore volume) The specific surface area and pore volume of the raw silica particles were determined using the BET method and BJH method based on nitrogen adsorption, with the specific surface area and pore distribution analyzer "BELSORP-miniII" (product name, manufactured by Microtrac-Bel Co., Ltd.).

[0067] (Average particle size) The average particle size of the raw silica particles and the average particle size of the hydrophobic silica particles were measured using a scanning electron microscope (a field emission scanning electron microscope "JSM-6701F" manufactured by JEOL Ltd.). The particles used were fixed to carbon tape and then coated with platinum (Pt). Images were taken with an acceleration voltage of 1 kV and an emission current of 10 μA. Thirty particles were randomly selected from the SEM images taken at 1000x magnification, and the average value of the X-axis constant diameter (Crumbein diameter) was calculated.

[0068] (Circularity) The circularity was calculated by determining the maximum diameter in the X-axis and Y-axis directions of a particle photographed at 10,000x magnification using a scanning electron microscope (JEOL Ltd.'s field emission scanning electron microscope "JSM-6701F"). The diameter in the direction with the larger value was defined as the major axis, and the diameter in the direction with the smaller value was defined as the minor axis. The circularity was then calculated using the following formula based on these values. Circularity = short axis (μm) / long axis (μm)

[0069] (Oil absorption amount) Oil absorption was measured according to JIS K 5101-13-1 (2004).

[0070] (Carbon content) The carbon content of hydrophobic silica particles was measured using an elemental analyzer (PerkinElmer CHN-2400). The sample amount was 10 mg, and the combustion conditions were 925°C for 60 seconds. The carbon content was measured from the generated carbon dioxide using frontal chromatography.

[0071] (Load density) The loading density of higher alcohols in hydrophobic silica particles was calculated using the following formula based on the value obtained from the measurement of "carbon content" described above.

[0072]

number

[0073] (degree of coupling) 1 g of hydrophobic silica particles were weighed into a beaker, 10 mL of tetrahydrofuran was added, and the mixture was dispersed in an ultrasonic cleaner for 5 minutes. The resulting slurry was filtered, washed with 20 mL of tetrahydrofuran and 20 mL of hexane, and dried at 70°C. The carbon content of hydrophobic silica particles after washing was measured using an elemental analyzer (PerkinElmer CHN-2400). The carbon content of hydrophobic silica particles before washing was also measured in the same manner, and the degree of bonding was calculated from the obtained values ​​using the following formula (1). Degree of bonding (%) = Carbon content of hydrophobic silica particles after washing (%) / Carbon content of hydrophobic silica particles before washing (%) × 100 ... (1)

[0074] (Coefficient of kinetic friction and coefficient of static friction) The coefficient of friction was determined using the static / dynamic friction measuring instrument "TL201Tt" (product name, manufactured by Trinity Lab Co., Ltd.). The contact was a urethane artificial finger, the load was 30 gf, the scanning distance was 40 mm, the scanning speed was 10 mm / sec, the coated substrate was artificial leather Supplele (manufactured by Ideatex Japan Co., Ltd.), and the coating amount of hydrophobic silica particles in each example was 0.8 μL / cm² as bulk volume per unit area. 2The coefficient of friction was measured. Of the obtained coefficients of friction, the average value in the range of 1,000 msec to 4,000 msec was used as the coefficient of kinetic friction. Furthermore, the static friction coefficient was determined from the maximum value in the range of 0 msec to 1,000 msec.

[0075] (water repellency) 0.05 g of hydrophobic silica particles were gently added to a 10 mL beaker containing 8 g of water. The water surface was then tapped 20 times to thoroughly spread the hydrophobic silica particles, and the mixture was left to stand at room temperature. The solution was visually observed daily, and the state of suspended and settled particles was evaluated. The evaluation criteria were as follows, and a rating of A is preferable in practical terms. The observation was carried out for 7 days. [Evaluation Criteria] A (Good): No particles were suspended or settled even after 7 days of standing. B (Slightly Good): After standing for 2-6 days, the particles were suspended or settled. C (Poor): After standing for 1 day, the particles were suspended or settled.

[0076] (Stability in oil) 4 mL of water and 4 mL of liquid paraffin were measured into the same container (a 13.5 mL transparent bottle with a lid). 0.05 g of hydrophobic silica particles were added to this two-layer solution and shaken 20 times. The mixture was then allowed to stand at room temperature. The solution was visually observed daily to assess the presence or absence of particles settling in the aqueous phase. The evaluation criteria were as follows, and a rating of A is preferable in practical terms. The observation was carried out for 7 days. [Evaluation Criteria] A (Good): Even after 7 days of standing, the particles had not settled in the aqueous phase. B (Slightly Good): After standing for 2-6 days, the particles had settled in the aqueous phase. C (Poor): After standing for 1 day, the particles had settled in the aqueous phase.

[0077] (Example 1) Hydrophobic silica particles supported with behenyl alcohol were obtained under the conditions shown in Table 1. Silica particles ("Sunsphere NP-30" manufactured by AGC SI-TEC Inc., average particle diameter 4.4 μm, specific surface area 48 m²) 2 30g of the mixture (38mL / 100g oil absorption capacity) and 0.9g of behenyl alcohol (Kao Corporation's "Calcol 220-80") were weighed into a sealed container and placed in a water bath set to 95°C, where they were heated and mixed for 2 hours. Next, 10 g of the mixture was weighed out and heated under reduced pressure at 180°C for 4 hours. After cooling, it was collected to obtain 9.9 g of hydrophobic silica particles.

[0078] (Example 2) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that the amount of behenyl alcohol used was 0.75 g.

[0079] (Example 3) Silica particles are manufactured by AGC SI-TEC Inc. as "Sunsphere L-51" (average particle size 6.2 μm, specific surface area 301 m²). 2 Hydrophobic silica particles were prepared in the same manner as in Example 1, except that the oil absorption capacity was changed to 168 mL / g and 15 g of silica particles and 3.75 g of behenyl alcohol were used.

[0080] (Example 4) Hydrophobic silica particles were prepared in the same manner as in Example 3, except that the amount of behenyl alcohol used was 3.0 g.

[0081] (Example 5) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that the heating temperature of the mixture was set to 160°C.

[0082] (Example 6) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that arachidyl alcohol (High-Nol 20SS, manufactured by Higher Alcohol Industry Co., Ltd.) was used instead of behenyl alcohol.

[0083] (Example 7) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that decyltetradecanol (Lisonol 24SP, manufactured by Higher Alcohols Co., Ltd.) was used instead of behenyl alcohol.

[0084] (Example 8) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that octyldodecanol (Lisonol 20SP, manufactured by Higher Alcohol Industry Co., Ltd.) was used instead of behenyl alcohol.

[0085] (Example 9) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that glycerol monostearate (NIKKOL MGS-F20V, manufactured by Nikko Chemicals Co., Ltd.) was used instead of behenyl alcohol, and 20 g of silica particles and 0.8 g of glycerol monostearate were used.

[0086] (Example 10) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that ethylene glycol monostearate (NIKKOL EGMS-70V, manufactured by Nikko Chemicals Co., Ltd.) was used instead of behenyl alcohol, and 20 g of silica particles and 0.8 g of ethylene glycol monostearate were used.

[0087] (Example 11) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that stearic acid monoethanolamide (Amizol SME, manufactured by Kawaken Fine Chemicals Co., Ltd.) was used instead of behenyl alcohol, and 20 g of silica particles and 0.8 g of stearic acid monoethanolamide were used.

[0088] (Example 12) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that Cerakyl alcohol (NIKKOL Cerakyl Alcohol V, manufactured by Nikko Chemicals Co., Ltd.) was used instead of behenyl alcohol, and 20 g of silica particles and 0.8 g of Cerakyl alcohol were used.

[0089] (Example 13) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that batyl alcohol (NIKKOL Batyl Alcohol 100, manufactured by Nikko Chemicals Co., Ltd.) was used instead of behenyl alcohol, and 20 g of silica particles and 0.8 g of batyl alcohol were used.

[0090] (Example 14) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that chimyl alcohol (NIKKOL Chimyl Alcohol 100, manufactured by Nikko Chemicals Co., Ltd.) was used instead of behenyl alcohol, and 20 g of silica particles and 0.8 g of chimyl alcohol were used.

[0091] (Example 15) Silica particles are manufactured by AGC SI-TEC Inc. as "Sunsphere L-51" (average particle size 6.2 μm, specific surface area 301 m²). 2 Hydrophobic silica particles were prepared in the same manner as in Example 1, except that the ratio was changed to (168 mL / g, oil absorption capacity 168 mL / 100 g), and Cerakil alcohol (NIKKOL Cerakil Alcohol V, manufactured by Nikko Chemicals Co., Ltd.) was used instead of behenyl alcohol, and 20 g of silica particles and 5.0 g of Cerakil alcohol were used.

[0092] (Example 16) Silica particles are manufactured by AGC SI-TEC Co., Ltd. as "FB-82" (average particle size 7.2 μm, specific surface area 142 m²). 2 Hydrophobic silica particles were prepared in the same manner as in Example 1, except that the oil absorption capacity was changed to 275 mL / g and 100 g, and 10 g of silica particles and 1.75 g of behenyl alcohol were used.

[0093] (Example 17) Hydrophobic silica particles were prepared in the same manner as in Example 16, except that the amount of behenyl alcohol used was 1.5 g.

[0094] (Example 18) Hydrophobic silica particles were prepared in the same manner as in Example 16, except that the amount of behenyl alcohol used was 1.25 g.

[0095] (Example 19) Hydrophobic silica particles were prepared in the same manner as in Example 16, except that the amount of behenyl alcohol used was 1.0 g.

[0096] (Example 20) Silica particles are manufactured by AGC SI-TEC Inc. as "Sunsphere L-52" (average particle size 5.2 μm, specific surface area 216 m²). 2 Hydrophobic silica particles were prepared in the same manner as in Example 1, except that the oil absorption capacity was changed to 292 mL / g and 100 g, and 10 g of silica particles and 2.5 g of behenyl alcohol were used.

[0097] (Example 21) Hydrophobic silica particles were prepared in the same manner as in Example 20, except that the amount of behenyl alcohol used was 2.25 g.

[0098] (Example 22) Hydrophobic silica particles were prepared in the same manner as in Example 20, except that the amount of behenyl alcohol used was 2.0 g.

[0099] (Example 23) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that the heating temperature of the mixture was set to 120°C.

[0100] (Example 24) Hydrophobic silica particles were prepared in the same manner as in Example 1, except that the heating temperature of the mixture was set to 140°C.

[0101] (Example 25) Hydrophobic silica particles were prepared in the same manner as in Example 3, except that the heating temperature of the mixture was set to 120°C.

[0102] For hydrophobic silica particles from Examples 1 to 25, circularity, average particle diameter, specific surface area, oil absorption, carbon content, higher alcohol loading density, degree of bonding, dynamic friction coefficient, and static friction coefficient were measured to evaluate water repellency and stability in oil. The results are shown in Table 2. Note that the number of days for water repellency and oil stability in Table 2 indicates the number of days elapsed since the suspension or precipitation of particles was confirmed.

[0103] [Table 1]

[0104] [Table 2]

[0105] The results in Table 2 show that the hydrophobic silica particles in Examples 1-22 had significantly higher bonding strength with higher alcohols compared to Examples 23-25, as measured by bonding strength testing. The hydrophobic silica particles in Examples 1-22 maintained their hydrophobicity well and also exhibited excellent water repellency and oil stability. Furthermore, from the comparison of Examples 1, 5, 23 and 24, and 4 and 25, it was found that a higher degree of bonding of the higher alcohol to the raw material silica particles results in superior water repellency and oil stability, and from Example 10, it was found that a bonding degree of 70% or more yields practically desirable water repellency and oil stability.

[0106] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2020-217209 filed on 25 December 2020 and Japanese Patent Application No. 2021-081180 filed on 12 May 2021, the contents of which are incorporated herein by reference.

Claims

1. A higher alcohol with 19 or more carbon atoms is supported on silica particles. The average particle size is 2 to 25 μm. The oil absorption capacity is 20-400 mL / 100 g. The amount of the higher alcohol supported is 1.0 μmol / m² or more. Hydrophobic silica particles having a degree of bonding of the higher alcohol to the silica particles of 70% or more, as measured by the following measurement method. Measurement method: 1 g of hydrophobic silica particles is dispersed in 10 mL of tetrahydrofuran, the dispersion is maintained for 5 minutes, and the filtered residue is washed with 20 mL of tetrahydrofuran and 20 mL of hexane and dried. The degree of bonding is defined as the ratio of the carbon content of the hydrophobic silica particles after washing to the carbon content of the hydrophobic silica particles before washing, as shown in formula (1) below. Degree of bonding (%) = Carbon content of hydrophobic silica particles after washing (%) / Carbon content of hydrophobic silica particles before washing (%) × 100 ... (1)

2. The hydrophobic silica particles according to claim 1, wherein the circularity is 0.95 or greater.

3. The specific surface area of ​​the silica particles, which are the base material, is 5 to 1000 m². ２ Hydrophobic silica particles according to claim 1 or 2, wherein the particle size is / g.

4. The hydrophobic silica particles according to any one of claims 1 to 3, wherein the degree of bonding is 80% or more.

5. A cosmetic composition containing hydrophobic silica particles as described in any one of claims 1 to 4.

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