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JP-7857323-B2 - Biodegradable spherical particles and method for producing the same

JP7857323B2JP 7857323 B2JP7857323 B2JP 7857323B2JP-7857323-B2

Inventors

  • 大村 雅也
  • 上野 瑞貴

Assignees

  • 株式会社ダイセル

Dates

Publication Date
20260512
Application Date
20240112

Claims (13)

  1. It contains biodegradable polymers as its main component, and in a biodegradation test in accordance with OECD TG301F, the degree of biodegradation on day 5, calculated by the following formula, is 40% or less. The biodegradable polymer is selected from the group consisting of polysaccharides (excluding polysaccharide esters) , polysaccharide esters, and aliphatic polyesters. Here, the total degree of substitution of the polysaccharide ester is greater than 0 and less than 0.7, The ratio BD5/BD28 of the biodegradation level BD5 on day 5 to the biodegradation level BD28 on day 28, as measured by a biodegradation test in accordance with OECD TG301F, is 0.60 or less. The average particle diameter is 0.08 μm or more and 40 μm or less . The sphericity is 0.9 or higher. The surface smoothness is 80% or higher. Biodegradable spherical particles. Biodegradability (%) = (BOD-B)/TOD x 100 (In the formula, BOD is the biochemical oxygen consumption by the test substance (mg), B is the biochemical oxygen consumption of the blank (mg), and TOD is the theoretical oxygen consumption by the test substance (mg).)
  2. The biodegradable spherical particles according to claim 1, wherein the coefficient of variation (CV) of particle size of the biodegradable spherical particles is 40% or less.
  3. The biodegradable spherical particles according to claim 1, wherein the biodegradation degree BD5 on day 5 and the biodegradation degree BD28 on day 28, as measured by a biodegradation test in accordance with OECD TG301F, satisfy the following formula. (BD28-BD5)/BD5 ≧ 0.50
  4. The biodegradable spherical particles according to claim 1, wherein, when observed using a scanning electron microscope at a magnification of 5000x over a 0.5 mm x 0.5 mm field of view, substantially no particles with micron-sized depressions are observed on their surface.
  5. The biodegradable spherical particles according to claim 1, wherein, when observed using a scanning electron microscope at a magnification of 5000x in a 0.5 mm × 0.5 mm field of view, there are substantially no particles exhibiting micron-sized protrusions extending from a virtual circle drawn along the arc of the spherical particle.
  6. The biodegradable spherical particles according to claim 1, wherein the polysaccharide (excluding polysaccharide esters) is one or two selected from cellulose and starch.
  7. The biodegradable spherical particles according to claim 1, wherein the aliphatic polyester is a polyhydroxyalkanoic acid, or a polymer of an aliphatic dicarboxylic acid and an aliphatic diol.
  8. The biodegradable spherical particles according to claim 1, wherein the aliphatic polyester is one or more selected from the group consisting of polycaprolactone, polyhydroxybutyric acid, and polylactic acid.
  9. A cosmetic composition comprising the biodegradable spherical particles described in claim 1.
  10. A mixture is obtained by mixing a biodegradable polymer, a plasticizer, and a water-soluble polymer. The mixture is melted and kneaded at a temperature of 200°C to 280°C to obtain a kneaded product. A method for producing biodegradable spherical particles according to claim 1, comprising removing the water-soluble polymer from the kneaded mixture.
  11. The method for producing biodegradable spherical particles according to claim 10, wherein, in the step of removing the water-soluble polymer from the kneaded product, the kneaded product is further mixed with a solvent containing one or more metal compounds selected from alkali metal compounds and alkaline earth metal compounds to hydrolyze the polysaccharide ester .
  12. The method for producing biodegradable spherical particles according to claim 11 , wherein the solvent is an aqueous solution of the metal compound.
  13. The method for producing biodegradable spherical particles according to claim 11 , wherein the metal compound is a hydroxide of an alkali metal or an alkaline earth metal.

Description

This disclosure relates to biodegradable spherical particles and methods for producing the same. More specifically, this disclosure relates to biodegradable spherical particles for use in cosmetic compositions and methods for producing the same. Traditionally, cosmetics have incorporated various polymer microparticles for purposes such as improving spreadability, altering texture, providing wrinkle-blurring effects, and enhancing the smoothness of foundations and other products. Microparticles with particularly high sphericity offer superior texture, and their physical properties and shape can produce a light-scattering (soft-focus) effect. When such microparticles are used in foundations and other products, they can fill in skin irregularities, smooth the skin, and scatter light in various directions, making wrinkles and other imperfections less noticeable (soft-focus effect). For use in such cosmetics, microparticles made from synthetic polymers such as polyamide, polymethyl methacrylate (PMMA), polystyrene, polypropylene, and polyethylene have traditionally been used. However, in recent years, due to environmental concerns, there has been a demand for microparticles made from biodegradable materials that possess the necessary properties while having a low environmental impact, as an alternative to these synthetic polymers. Patent Document 1 (Japanese Patent No. 6872068) discloses resin beads mainly composed of cellulose, wherein the cumulative 50% particle size by volume is 50 μm or less, the sphericity is 0.7 to 1.0, the surface smoothness is 70 to 100%, the solidity is 50 to 100%, the 5-day biodegradation rate measured in accordance with JIS K6950 is 20% or more, and the cellulose content in the resin is 90 to 100% by mass. Patent Document 2 discloses a spherical cellulose powder having an average primary particle diameter of 5 μm or less, with the primary particle diameter of 90% or more of the total particles in the range of 2 to 7 μm, a ratio of the longest diameter to the shortest diameter of the sphere (longest diameter/shortest diameter) in the range of 1.0 to 2.5, a haze value of 70% or more for 20% by mass of silicone oil paste, and a total light transmittance of 95% or more. Patent Document 3 describes a method for preparing a dispersion by kneading a resin component (A), such as a thermoplastic resin, with a water-soluble additive component (B). The additive component (B) is then eluted from this dispersion to produce a molded article (e.g., a porous body, spherical particles) composed of the resin component (A). The document also describes cellulose derivatives, polylactic acid, and the like as examples of the resin component (A). Patent No. 6872068Japanese Patent Publication No. 2013-221000Japanese Patent Publication No. 2004-051942 Figure 1 shows a scanning electron microscope (SEM) image (magnification: 800x) of the particles of Example A-1.Figure 2 shows a scanning electron microscope (SEM) image (magnification: 5000x or higher) of the particles of Example A-1.Figure 3 shows a scanning electron microscope (SEM) image (magnification: 800x) of the particles of Comparative Example A-2.Figure 4 shows a scanning electron microscope (SEM) image (magnification: 5000x or higher) of the particles of Comparative Example A-2.Figure 5 shows a scanning electron microscope (SEM) image (magnification: 800x) of the particles of Example A-1 after the decomposition treatment.Figure 6 shows a scanning electron microscope (SEM) image (magnification: 15,000x) of the particles of Example A-1 after the decomposition treatment.Figure 7 shows a scanning electron microscope (SEM) image (magnification: 800x) of the particles of Comparative Example A-2 after decomposition treatment.Figure 8 shows a scanning electron microscope (SEM) image (magnification: 5000x) of the particles of Comparative Example A-2 after decomposition treatment. The present disclosure will be described in detail below based on preferred embodiments. Each configuration and combination thereof in each embodiment is an example, and additions, omissions, substitutions, and other modifications are possible as appropriate, without departing from the spirit of the present disclosure. This disclosure is not limited by the embodiments, but only by the scope of the claims. Furthermore, each aspect disclosed herein can be combined with any other features disclosed herein. In this specification, the range "X to Y" means "X or greater and Y or less," "ppm" means "ppm by weight," and unless otherwise noted, all test temperatures are room temperature (20°C ± 5°C). [Biodegradable spherical particles] The biodegradable spherical particles of this disclosure (hereinafter sometimes referred to as "spherical particles") are particles whose main component is a biodegradable polymer. Here, "main component" means that the most abundant component among the constituent components of the particle is a biodegradable polymer, and that its content is at least 50% by weig