Glass powder

Abstract

The present invention provides a glass powder in which D50 is 1-15 μm and D50 / 2 is not less than 8%. The present invention provides a glass powder that exhibits a hardness A of not less than 1.5 as measured when the glass powder is formed into a cylindrical press-formed body having a height of 5 mm. D50 / 2 is the proportion of the cumulative volume up to a particle size that is 1 / 2 of D50, of the cumulative volume of the particle size distribution measured with a laser diffraction / scattering method. The press-formed body is obtained by applying a pressure of 4 MPa. The hardness A is measured using a type-A durometer stipulated in JISK 6253-2012.

Description

Glass powder

[0001] The present invention relates to glass powders, and more particularly to glass powders suitable for use in, for example, cosmetics.

[0002] Cosmetics may contain powders to improve slipperiness, impart a light scattering effect, and the like. Powders are often used in makeup cosmetics, typified by foundations. Examples of organic powders that have been used include silicone, cellulose, and nylon. Examples of inorganic powders that have been used include silica and glass. Patent Document 1 discloses a transparent solid composition that contains spherical powders with an average particle size of 3 to 30 μm as a cosmetic.

[0003] Japanese Patent Application Laid-Open No. 2005-213145

[0004] Unlike organic powders, inorganic powders such as glass powder do not generate microplastics after disposal. However, inorganic powders can cause dryness and roughness on the skin. Furthermore, inorganic powders can also impair the formability of pressed powder-type cosmetics. Therefore, an object of the present invention is to provide a glass powder suitable for use in cosmetics.

[0005] In a first aspect, the present invention provides a glass powder having a D50 of 1 μm or more and 15 μm or less, and a D50 / 2 of 8% or more, where D50 is the particle size at which the cumulative volume from the smaller particle size side in a particle size distribution measured by a laser diffraction / scattering method is 50%, and D50 / 2 is the ratio of the cumulative volume from the smaller particle size side in the particle size distribution to a particle size that is 1 / 2 of the D50.

[0006] In a second aspect, the present invention provides a glass powder having a hardness A of 1.5 or more, measured when the glass powder is pressed into a cylindrical press-molded body having a height of 5 mm, wherein the press-molded body is obtained by using a mold having a cylindrical cavity therein to fill the glass powder therein and applying a pressure of 4 MPa along the height direction of the cylinder, and the hardness A is measured using a Type A durometer specified in Japanese Industrial Standards (JIS) K 6253-2012.

[0007] According to the present invention, a glass powder suitable for use in cosmetics is provided. In at least preferred embodiments, the present invention can achieve at least one effect selected from the following i) and ii): i) It is likely to impart a moist feeling to the skin. ii) It is unlikely to inhibit the formability of pressed powder-type cosmetics.

[0008] FIG. 1 is a diagram showing the results of observing a glass powder according to an example of the present invention with a scanning electron microscope (SEM).

[0009] The following describes embodiments of the present invention, but the following description is not intended to limit the present invention to a specific embodiment. In this specification, "major component" refers to the component with the highest content by mass. "Spherical" refers to a shape in which the ratio R2 / R1 of the diameter R2 perpendicular to the longest diameter R1 to the longest diameter R1 of the particle is 0.8 or greater. "True spherical" refers to a shape in which the ratio R2 / R1 of the diameter R2 perpendicular to the longest diameter R1 to the longest diameter R1 of the particle is 0.9 or greater. The determination of whether a shape corresponds to "spherical" or "true spherical" can be made based on an image observed using an SEM. The phrase "substantially composed of glass particles" means that 90% or more, and even 95% or more of the glass particles constituting the glass powder by number correspond to the specified glass particles. However, the ratio by number can be determined based on 50 arbitrarily selected particles. The upper and lower limits of the numerical values ​​described below are not specified individually, but can be any combination of ranges.

[0010] (Particle size distribution) The D50 of the glass powder of this embodiment may be 1 μm or more, 2 μm or more, 3 μm or more, or even 4 μm or more. If the D50 is too small, the dispersibility of the glass powder in cosmetics may be reduced. The D50 may be 15 μm or less, 13 μm or less, 11 μm or less, or even 10.5 μm or less. If the D50 is too large, a good feel on the skin may not be maintained. The D50 / 2 may be 8% or more, 10% or more, 12% or more, 14% or more, or even 16% or more, and in some cases may be 18% or more. The D50 / 2 is an index indicating the proportion of particles with relatively small particle sizes. The upper limit of D50 / 2 is not particularly limited, but may be 40% or less, 35% or less, or even 30% or less.

[0011] Glass powders with a D50 / 2 that is not too small tend to provide a moist feeling to the skin. This is thought to be because small particles are sufficiently interposed between relatively large particles when they come into contact with the skin. Glass powders are relatively hard compared to organic powders, and are inherently disadvantageous in providing a moist feeling. The ability to provide a moist feeling by controlling the particle size distribution is useful in mass production, for example, because it can eliminate the need for surface modification of inorganic powders.

[0012] Glass powders with a D50 / 2 that is not too small are also excellent in that they are less likely to impair the moldability of cosmetics. The degree of influence on the moldability of cosmetics can be evaluated based on the moldability of the glass powder itself. The moldability of glass powders can be evaluated based on the hardness of press-molded bodies of the glass powder.

[0013] The lower limit of D10 of the glass powder is not particularly limited, but may be 0.3 μm or more, 0.7 μm or more, or even 1 μm or more. The upper limit of D10 is also not particularly limited, but may be 8 μm or less, 5 μm or less, or even 3 μm or less. The lower limit of D90 of the glass powder is also not particularly limited, but may be 1 μm or more, 5 μm or more, or even 7 μm or more. The upper limit of D90 is also not particularly limited, but may be 50 μm or less, 40 μm or less, or even 25 μm or less. Note that D10 and D90 can be determined by replacing "50%" of D50 with "10%" or "90%, respectively.

[0014] The ratio of D90 to D10, D90 / D10, is an index showing the spread of the particle size distribution. D90 / D10 is not particularly limited, but may be 4 or more, 5 or more, or even 6 or more. D90 / D10 is not particularly limited, but may be 50 or less, 30 or less, 15 or less, 12 or less, or even 10 or less, or in some cases 9 or less. A D90 / D10 in an appropriate range, particularly a D90 / D10 in a range of 4 or more to 20 or less, 5 or more to 10 or less, or even 5 or more to 9 or less, is appropriate for mitigating the degree of influence on the formability of a cosmetic.

[0015] (Hardness of Press-Molded Product) The hardness A of the press-molded product of the glass powder of this embodiment may be 1.5 or more, 2 or more, or even 2.2 or more, and in some cases 2.5 or more, particularly 3 or more. A high hardness of the press-molded product of the glass powder serves as an indicator of mitigating the influence on the moldability of a cosmetic containing the glass powder. The upper limit of the hardness A of the press-molded product of the glass powder is not particularly limited, but is, for example, 20 or less, and even 10 or less. However, the hardness A is based on the hardness measured using a Type A durometer. Described based on the hardness F measured using an Asker rubber hardness tester, the hardness (hardness F) of the press-molded product of the glass powder of this embodiment may be 60 or more, 70 or more, 80 or more, 90 or more, or even 95 or more. Details of the method for preparing the press-molded product as a test specimen and the method for evaluating the hardness A and F are described in the Examples section. It is assumed that glass powders with high press-molded hardness have a sufficient number of relatively small particles interposed between relatively large particles.

[0016] (Composition of Glass Powder) The composition of the glass powder is not particularly limited and may be any of various compositions containing an oxide, for example, silicon oxide, as a main component. The glass composition containing silicon oxide as a main component may be any of various compositions known as soda-lime glass, borosilicate glass, aluminosilicate glass, etc. The glass composition may be represented by the INCI (International Nomenclature of Cosmetic Ingredients) name, and may correspond to at least one composition selected from the group consisting of borosilicate (Al / Ca / copper / Na), borosilicate (Ca / Al), borosilicate (Ca / Na), and borosilicate (Ca / titanium). The glass composition may be represented by the INCI name, and may correspond to at least one composition selected from the group consisting of borosilicate (Ca / Al), borosilicate (Ca / Na), and borosilicate (Ca / titanium). The glass composition may be represented by the INCI name as at least one composition selected from the group consisting of borosilicate (Ca / Al) and borosilicate (Ca / Na). In the above-mentioned composition names containing "borosilicate" in the INCI name, the boron oxide content may be 0 to 13% by mass. In other words, even a glass composition that does not contain boron oxide may be classified as a composition containing "borosilicate" in the INCI name. The glass powder composition may have a higher calcium oxide content than ordinary soda-lime glass, specifically, a calcium oxide content of 16% or more, or even 18% or more, by mass. The glass powder composition may have a higher aluminum oxide content than ordinary soda-lime glass, specifically, an aluminum oxide content of 5% or more, or even 8% or more, by mass. The glass powder composition may have a lower sodium oxide content than ordinary soda-lime glass, specifically, an aluminum oxide content of 10% or less, or even 7% or less, by mass. Furthermore, glass compositions having a softening point higher than that of soda-lime glass, specifically glass compositions having a softening point of 780° C. or higher, 800° C. or higher, or even 830° C. or higher, are suitable for the glass powder of this embodiment. 7.6 This is the temperature at which the viscosity becomes dPa·s.

[0017] (Shape of particles constituting glass powder, etc.) The shape of the particles constituting the glass powder is not particularly limited, and may be spherical or truly spherical. The glass powder may be substantially composed of spherical glass particles. The glass powder may be substantially composed of truly spherical glass particles. However, the glass powder of this embodiment may have various shapes. Furthermore, the glass powder may be substantially composed of solid glass particles. Solid glass particles are more suitable for providing a sufficient moist feeling than hollow glass particles.

[0018] (Method for manufacturing glass powder) In this embodiment, the glass powder can be obtained, for example, by a manufacturing method including pulverizing a raw glass powder. The pulverization step is not particularly limited, and can be performed using, for example, various known mills. The raw glass powder is also not particularly limited, and raw powders having various shapes such as pellets, flakes, and spheres can be used.

[0019] The grinding conditions for adjusting the particle size vary depending on the grinding method. For example, in the case of a ball mill, the well-known conditions include grinding time, rotation speed, ball filling rate, ball diameter, etc. After grinding, glass powder having a diameter exceeding or less than a predetermined diameter may be removed, for example, using a sieve or filter. The adjustment of the particle size distribution itself can be carried out by applying a known technique.

[0020] The method for producing glass powder may further include spheronizing the glass powder obtained by pulverization. The spheronization step can be performed, for example, by heating the glass powder. The heating temperature can be determined taking into consideration the composition, particle size distribution, etc. of the glass powder. If the heating temperature is too high, glass powder with a small particle size may foam. Furthermore, a moderately low heating temperature is suitable for maintaining the proportion of relatively small particles constituting the glass powder. According to the inventor's research, the heating temperature that has been conventionally applied and is preferable for improving production efficiency reduces the proportion of relatively small particles that can be represented by D50 / 2.

[0021] (Cosmetics) The cosmetics to be blended with the glass powder of this embodiment are not particularly limited, but suitable examples include makeup cosmetics such as foundation, face powder, etc. There are also no particular limitations on the shape of the cosmetics, but the glass powder of this embodiment is suitable for blending in solid cosmetics.

[0022] The content of the glass powder of this embodiment in the cosmetic may be, for example, 0.1% or more, 5% or more, or even 10% or more by mass. The upper limit of this content is not particularly limited, but may be 90% or less, or even 50% or less.

[0023] As described above, the present embodiment provides the following techniques.

[0024] The first technology is a glass powder having a D50 of 1 μm or more and 15 μm or less, and a D50 / 2 of 8% or more, where D50 is the particle size at which the cumulative volume from the smaller particle size side in the particle size distribution measured by a laser diffraction / scattering method is 50%, and D50 / 2 is the ratio of the cumulative volume from the smaller particle size side in the particle size distribution to a particle size half of the D50.

[0025] The second technology is the glass powder according to the first technology, which has a hardness A of 1.5 or more when measured after being molded into a cylindrical press-molded body having a height of 5 mm, wherein the press-molded body is obtained by using a mold having a cylindrical void therein to fill the glass powder therein and applying a pressure of 4 MPa along the height direction of the cylinder, and the hardness A is measured using a Type A durometer specified in Japanese Industrial Standards (JIS) K 6253-2012.

[0026] The third technology is a glass powder having a hardness A of 1.5 or more measured when molded into a cylindrical press-molded body having a height of 5 mm, where the press-molded body is obtained by using a mold having a cylindrical cavity therein to fill the glass powder therein and applying a pressure of 4 MPa along the height direction of the cylinder, and the hardness A is measured using a Type A durometer specified in Japanese Industrial Standards (JIS) K 6253-2012.

[0027] A fourth technology is the glass powder according to any one of the first to third technologies, which is substantially composed of spherical glass particles, where the spherical shape is a shape in which, in an image of the particles observed using a scanning electron microscope, the ratio R2 / R1 of the longest diameter R1 to the diameter R2 perpendicular to the longest diameter R1 is 0.8 or more.

[0028] A fifth technology is the glass powder according to any one of the first to fourth technologies, wherein the ratio of D90 to D10, D90 / D10, is 4.0 or more, where D10 is the particle size at which the cumulative volume from the smaller particle size side in a particle size distribution measured by a laser diffraction / scattering method is 10%, and D90 is the particle size at which the cumulative volume from the smaller particle size side in the particle size distribution is 90%.

[0029] A sixth technology is the glass powder according to any one of the first to fifth technologies, which has a glass composition having a softening point of 780° C. or higher.

[0030] The seventh technology is the glass powder according to the first technology, which has a hardness F of 60 or more when measured after being pressed into a cylindrical press-molded body having a height of 5 mm. The press-molded body is obtained by using a mold having a cylindrical cavity inside to fill the glass powder inside the mold and applying a pressure of 4 MPa along the height direction of the cylinder, and the hardness F is measured using an Asker rubber hardness tester, type F.

[0031] An eighth technology is a cosmetic comprising the glass powder according to any one of the first to seventh technologies.

[0032] The present embodiment also provides the following ninth technique. The ninth technique is a glass powder that has a hardness F of 60 or more when it is pressed into a cylindrical press-molded body having a height of 5 mm. The press-molded body is obtained by using a mold having a cylindrical cavity inside to fill the glass powder inside the molded body and applying a pressure of 4 MPa along the height direction of the cylinder, and the hardness F is measured using an Asker rubber hardness tester, type F.

[0033] The present invention will now be described in more detail with reference to examples. First, specific evaluation methods will be described.

[0034] (Particle size distribution) The particle size distribution of the glass powder was measured using a laser diffraction / scattering method. A particle size distribution measuring device ("MT3300EXII" manufactured by Microtrac) was used for the measurement. The particle sizes corresponding to 10%, 50%, and 90% of the total volume from the smallest particle size were measured as D10, D50, and D90, respectively. The ratio of the total volume of particles from the smallest particle size to half the particle size of D50 was obtained as D50 / 2. Furthermore, D90 / D10 was calculated.

[0035] (Sensory evaluation) A small amount of glass powder was taken on a finger and applied to the back of the hand, and the feel and dryness of the powder were evaluated. The feel was evaluated as either moist or smooth. The dryness was evaluated on a three-point scale: G: not dry, F: slightly dry, and NG: very dry.

[0036] (Shape Retention and Hardness of Press-Molded Articles) - Molding of Press-Molded Articles Glass powder was compression-molded using a mold to obtain a cylindrical press-molded article. The press-molded article had a circular bottom with a diameter of 58 mm and a height of 5 mm. Compression molding was performed by applying a pressure of 4 MPa along the height direction of the cylinder. - Shape Retention A pressure of 10 kPa was applied to a circular region within a range of 10 mm from the center of the bottom surface of the press-molded article, and the change in shape of the press-molded article was observed. The results were evaluated on a two-level scale: G: not easily crumbled, and NG: easily crumbled. - Hardness The hardness A and F of the bottom surface of the press-molded article were measured using a Type A durometer specified in JIS K 6253-2012 and an Asker Rubber Hardness Tester Type F manufactured by Kobunshi Keiki Co., Ltd. The measurement time was 1 second, i.e., the reading within 1 second after the durometer or the like was brought into contact with the press-molded article was taken as the hardness.

[0037] Example 1 Glass particles having a glass composition corresponding to borosilicate (Ca / Al) were pulverized in a ball mill to obtain glass powder. The glass composition of the borosilicate (Ca / Al) used is shown in Table 1. However, since this glass composition also corresponds to borosilicate (Ca / Na) and borosilicate (Ca / titanium), it can be expressed as any of the three types including borosilicate (Ca / Al). The softening point of this glass composition was 876°C. The ball milling conditions were adjusted so that the glass powder had a D50 of 6 μm. The glass powder after pulverization had a shape that did not correspond to a spherical shape. Next, the obtained glass powder was spheroidized using a flame-type spheroidizer (Taiyo Nippon Sanso Corporation, "CERAMELT"). The burner combustion temperature of the spheroidizer was adjusted to a range of 2000 to 2400°C. The glass powder was supplied at a rate of 10 kg / h using a raw material feeder. The supplied glass powder was heated and spheroidized. The spheroidized glass particles were collected using a cyclone. Meanwhile, fine powder of several hundred nanometers or less was collected using a bag filter and separated from the glass particles.

[0038]

[0039] Example 2 Glass granules were obtained in the same manner as in Example 1, except that the grinding conditions were changed, specifically, the size of the balls charged into the ball mill was increased.

[0040] Comparative Example 1 Glass granules were obtained in the same manner as in Example 2, except that the spheroidizing conditions were changed. The burner combustion temperature of the spheroidizing apparatus was adjusted to the range of 2400 to 2700°C.

[0041] Comparative Example 2 Glass granules were obtained in the same manner as in Example 1, except that commercially available soda-lime glass particles were used and the grinding conditions were changed, specifically, the ball size was made larger than in Example 2. The softening point of the soda-lime glass used was about 730°C.

[0042] Comparative Examples 3 and 4 In Comparative Example 3, spherical silica (AGC Si-Tech Co., Ltd. "L-51") was used instead of glass particles, and in Comparative Example 4, spherical silicone (Shin-Etsu Chemical Co., Ltd. "KSP-100") was used instead of glass particles, and measurements were carried out.

[0043] The measurement results are summarized in Table 2.

[0044]

[0045] In Comparative Examples 3 and 4, the press-molded body broke during hardness measurement, so hardness measurements could not be obtained. Furthermore, when observed using an SEM, the glass powders obtained in Examples 1 and 2 were substantially composed of spherical, solid particles. The glass powders obtained in Comparative Examples 1 and 2 were also spherical. Similarly, an SEM photograph of the glass powder of Example 1 is shown in FIG. 1 .

[0046] Next, foundations were prepared and evaluated using the powders obtained in Example 1 and Comparative Examples 1 and 3. The evaluation methods were as described above. The formulations of the foundations and the evaluation results are shown in Table 3.

[0047]

Claims

1. A glass powder having a D50 of 1 μm or more and 15 μm or less, and a D50 / 2 of 8% or more, where D50 is the particle size at which the cumulative volume from the small particle size side in the particle size distribution measured by a laser diffraction / scattering method is 50%, and D50 / 2 is the ratio of the cumulative volume from the small particle size side in the particle size distribution to a particle size that is 1 / 2 of the D50.

2. The glass powder according to claim 1, which has a hardness A of 1.5 or more when it is pressed into a cylindrical press molded body having a height of 5 mm, wherein the press molded body is obtained by applying a pressure of 4 MPa along the height direction of the cylinder to the glass powder filled in a die having a cylindrical cavity therein, and the hardness A is a hardness measured using a type A durometer specified in Japanese Industrial Standards (JIS) K 6253-2012.

3. A glass powder having a hardness A of 1.5 or more, measured after being molded into a cylindrical press molded body having a height of 5 mm, wherein the press molded body is obtained by applying a pressure of 4 MPa along the height direction of the cylinder to the glass powder filled in a mold having a cylindrical cavity therein, and the hardness A is measured using a type A durometer specified in Japanese Industrial Standards (JIS) K 6253-2012.

4. The glass powder according to claim 1 or 3, which is substantially composed of spherical glass particles, wherein the spherical shape is such that in an image of the particles observed using a scanning electron microscope, the ratio R2 / R1 of the longest diameter R1 to the diameter R2 perpendicular to said diameter R1 is 0.8 or more.

5. The glass powder according to claim 1 or 3, wherein the ratio of D90 to D10, D90 / D10, is 4.0 or more, where D10 is the particle size at which the cumulative volume from the smaller particle size side in a particle size distribution measured by a laser diffraction / scattering method is 10%, and D90 is the particle size at which the cumulative volume from the smaller particle size side in the particle size distribution is 90%.

6. The glass powder according to claim 1 or 3, which has a glass composition having a softening point of 780° C. or higher.

7. The glass powder according to claim 1 or 3, which is formed into a cylindrical press-molded body having a height of 5 mm and has a hardness F of 60 or more when measured, provided that the press-molded body is obtained by applying a pressure of 4 MPa along the height direction of the cylinder to the glass powder filled in a die having a cylindrical cavity therein, and the hardness F is a hardness measured using an Asker rubber hardness tester type F.

8. A cosmetic comprising the glass powder according to claim 1 or 3.

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