Resin particles and use thereof

Abstract

The purpose of the present invention is to provide resin particles that can easily be washed away even if adhered to equipment.　These resin particles contain a polyester resin, and have an average circularity of 0.9 or less and a loose bulk density of 0.1 to 0.5 g / cm3. The concealment rate is preferably 50% or less. The linseed oil absorption amount is preferably 150 to 500 ml / 100 g. The apparent specific gravity is preferably 2.0 or less. The relative density indicated by formula (1) is preferably 0.6 g / cm3 or less. (1): Relative density (g / cm3) = loose bulk density (g / cm3) ÷ apparent specific gravity

Description

Resin particles and their uses

[0001] The present invention relates to resin particles and uses thereof.

[0002] Particles are widely used in cosmetics, paints, optical applications, resins, building materials, and more. Required particle functions include light diffusion, opacity, coatability, and tactile sensation. Particle materials include particles made from a variety of materials, including organic and inorganic substances. Organic particles have a softer feel than inorganic particles, making them preferred for tactile sensation in cosmetics and paints. Furthermore, the optical properties of particles have been explored for applications such as soft-focus effects that reduce the appearance of pores and wrinkles, and for improving brightness in cosmetics. Examples of organic particles include acrylic, styrene, urethane, and silicone polymer particles. In recent years, growing environmental concerns have led to a demand for particles with low environmental impact, with biodegradable particles receiving particular attention. For example, Patent Document 1 describes a method for producing polylactic acid-based resin microparticles made from polylactic acid derived from non-petroleum sources, and polylactic acid-based resin microparticles as environmentally friendly particles. Patent Document 2 also describes porous resin microparticles made from biodegradable polyester-based thermoplastic resins. However, these particles are porous particles obtained by dissolving the resin component in an organic solvent, so cavities tend to form inside the particles. When these particles are incorporated into cosmetics, paints, etc., the whiteness increases and the transparency of the coating film cannot be maintained. Patent Document 3 also describes approximately spherical resin microparticles with a sphericity of 0.90 to 1.00 and a light scattering index of 0.5 to 1.0. However, because these are solid particles with high sphericity, they have low oil absorption and require the incorporation of a large amount to achieve a certain level of effect. Furthermore, conventional particles have a problem of high loss during the manufacturing process, resulting in low yield rates.

[0003] International Publication No. WO2012 / 105140 International Publication No. WO2017 / 056908 Japanese Patent Application Laid-Open No. 2016-222897

[0004] An investigation into the causes of this yield rate decline revealed that the adhesion of resin particles to manufacturing equipment had a significant impact. Roughly spherical particles have particularly high agglomeration properties, so they adhere firmly to equipment, resulting in a significant decline in yield. Furthermore, firmly adhered resin particles need to be removed because they may cause foreign matter to be mixed into other product numbers. However, this can require strong external force and long cleaning times, or require labor-intensive work such as disassembling and cleaning the equipment. These processes are labor-intensive and time-consuming, hindering manufacturing efficiency. Therefore, the present invention aims to provide resin particles that can be easily washed away even if adhesion occurs. The resin particles of the present invention not only improve the efficiency of the manufacturing process, but also contribute to reducing equipment maintenance costs.

[0005] As a result of extensive research to achieve the above object, the present inventors have found that resin particles containing a polyester resin and having an average circularity and loose bulk density within specific ranges can be easily washed away, and have arrived at the present invention. That is, the present invention includes the following aspects <1> to <8>. <1> A resin particle containing a polyester resin, having an average circularity of 0.9 or less and a loose bulk density of 0.1 to 0.5 g / cm ３ <2> The resin particles according to <1>, which have a hiding power of 50% or less. <3> The resin particles according to <1> or <2>, which have a linseed oil absorption of 150 to 500 ml / 100 g. <4> The resin particles according to any one of <1> to <3>, which have an apparent specific gravity of 2.0 or less. <5> The resin particles according to any one of <1> to <3>, which have a relative density of 0.6 g / cm as defined by the following formula (1): ３ <4> Resin particles according to any one of <1> to <4>, which have a relative density (g / cm ３ ) = loose bulk density (g / cm ３ ) ÷ apparent specific gravity (1) <6> A composition comprising the resin particles according to any one of <1> to <5>. <7> A cosmetic comprising the resin particles according to any one of <1> to <5>. <8> A coating composition comprising the resin particles according to any one of <1> to <5>.

[0006] The resin particles of the present invention can be easily washed away.

[0007] Electron microscope photograph of resin particles 1 of Example 1

[0008] The resin particles of the present invention contain a polyester resin, have an average circularity of 0.9 or less, and a loose bulk density of 0.1 to 0.5 g / cm ３ The reason why the resin particles of the present invention can be easily washed off even after adhesion is not particularly limited, but when the average circularity is 0.9 or less, the particle shape becomes non-uniform and the contact area increases compared to spherical particles, so that when washed off with water or the like, the water quickly penetrates the resin particle surface, making it easy for the resin particles to loosen from each other, and the loose bulk density is 0.1 to 0.5 g / cm ３ It is believed that this is because the number of voids between the resin particles increases, and flow paths for water, etc. are efficiently formed. The resin particles of the present invention (hereinafter, sometimes simply referred to as particles) will be described below.

[0009] [Resin Particles] The average circularity of the particles of the present invention is 0.9 or less. When the circularity is 0.9 or less, the particle shape becomes non-uniform, resulting in excellent permeability. The lower limit of the circularity is preferably 0.20, more preferably 0.25, even more preferably 0.30, and particularly preferably 0.35. The upper limit of the circularity is preferably 0.85, more preferably 0.80, and even more preferably 0.75. For example, 0.20 to 0.85 is preferred, and 0.40 to 0.75 is even more preferred. Furthermore, in order to make the particles flat and more likely to satisfy the loose bulk density of the present invention, the circularity is preferably 0.8 or less, more preferably 0.7 or less, and particularly preferably 0.6 or less. The circularity of the particles described in the present invention is determined by the method described in the Examples.

[0010] The loose bulk density of the particles of the present invention is 0.1 to 0.5 g / cm ３ When the loose bulk density is within this range, flow paths for water and the like are efficiently formed, resulting in excellent cleaning properties. The lower limit of the loose bulk density is preferably 0.12 g / cm ３ , more preferably 0.14 g / cm ３ , more preferably 0.16 g / cm ３ , particularly preferably 0.18 g / cm ３On the other hand, the upper limit of the loose bulk density is preferably 0.45 g / cm ３ , more preferably 0.40 g / cm ３ , more preferably 0.35 g / cm ３ In addition, for example, 0.12 to 0.45 g / cm ３ is preferably 0.18 to 0.35 g / cm ３ The loose bulk density of the particles described in the present invention is determined by the method described in the Examples.

[0011] The apparent specific gravity of the particles of the present invention is preferably 2.0 or less, since this slows the settling rate of the particles. The lower limit of the apparent specific gravity is more preferably 0.85, even more preferably 0.90, and particularly preferably 0.95. On the other hand, the upper limit of the apparent specific gravity is more preferably 1.8, even more preferably 1.6, and particularly preferably 1.4. Furthermore, for example, the apparent specific gravity is more preferably 0.85 to 1.8, and even more preferably 0.95 to 1.4. The apparent specific gravity of the particles described in the present invention is determined by the method described in the Examples.

[0012] The relative density of the particles of the present invention is 0.6 g / cm because the particles have high fluidity. ３ The lower limit of the relative density is preferably 0.05 g / cm or less. ３ More preferably, 0.10 g / cm ３ is more preferably 0.15 g / cm ３ On the other hand, the upper limit of the relative density is 0.55 g / cm ３ More preferably, 0.50 g / cm ３ is more preferably 0.45 g / cm ３ is particularly preferable. Furthermore, for example, 0.05 to 0.55 g / cm ３ More preferably, 0.10 to 0.45 g / cm ３ The relative density of the particles described in the present invention is the relative density (g / cm ) represented by the following formula (1): ３ ) = loose bulk density (g / cm ３ ) ÷ apparent specific gravity... (1)

[0013] The hiding ratio of the particles of the present invention is preferably 50% or less in terms of transparency when incorporated into a coating film. The upper limit of the hiding ratio is 30%, more preferably 20%, and particularly preferably 10%. On the other hand, the lower limit of the hiding ratio is preferably 0%, more preferably 1%. Also, for example, 40% to 0% is preferred, and 20% to 0% is more preferred. The hiding ratio of the particles described in the present invention is determined by the method described in the Examples.

[0014] The volume average particle diameter of the resin particles of the present invention is preferably 1 to 50 μm in terms of fluidity and transparency when incorporated into a coating film. The lower limit of the particle diameter is more preferably 1.5 μm, even more preferably 2.0 μm, and particularly preferably 2.5 μm. Meanwhile, the upper limit of the particle diameter is more preferably 40 μm, even more preferably 35 μm, and particularly preferably 30 μm. Also, for example, 1 to 40 μm is preferred, more preferably 1.5 to 30 μm, and particularly preferably 2 to 20 μm. The volume average particle diameter of the resin particles is measured by the method described in the Examples.

[0015] The coefficient of variation CV of the particle size distribution of the resin particles of the present invention is not particularly limited, but is preferably 2 to 70% in that it is easier to satisfy the loose bulk density of the present invention. The upper limit of the coefficient of variation CV is preferably 65% ​​or less, more preferably 60% or less, even more preferably 55% or less, and particularly preferably 50% or less. The lower limit of the coefficient of variation CV is preferably 3%, more preferably 5%, and particularly preferably 7%. Furthermore, for example, 3 to 65% is more preferable, and 5 to 60% is even more preferable. The coefficient of variation CV refers to a value calculated using the following calculation formulas (2) and (3).

[0016] (where s is the standard deviation of particle diameter, <x> is the average particle diameter, x ｉ is the diameter of the i-th particle, and n is the number of particles.)

[0017] The linseed oil absorption of the resin particles of the present invention is preferably 150 to 500 mL / 100 g in order to achieve high fluidity and good handleability. The lower limit of the oil absorption is preferably (1) 160 mL / 100 g, (2) 170 mL / 100 g, (3) 180 mL / 100 g, and (4) 190 mL / 100 g (the larger the number in parentheses, the more preferable it is). Meanwhile, the upper limit of the oil absorption is preferably (1) 480 mL / 100 g, (2) 460 mL / 100 g, (3) 440 mL / 100 g, (4) 420 mL / 100 g, (5) 400 mL / 100 g, (6) 380 mL / 100 g, and (7) 360 mL / 100 g (the larger the number in parentheses, the more preferable it is). For example, the linseed oil absorption of the particles is more preferably 160 to 480 mL / 100 g, and even more preferably 180 to 440 mL / 100 g. The linseed oil absorption of the particles is measured by the method described in the Examples.

[0018] [Polyester Resin] The resin particles of the present invention contain a polyester resin. The polyester resin is not particularly limited, but is preferably one having excellent biodegradability and a relative density of 0.6 g / cm ３ In terms of ease of adjustment, the resin is preferably at least one selected from aliphatic polyester resins and aliphatic-aromatic polyester resins, with aliphatic polyester resins being particularly preferred.

[0019] The aliphatic polyester resin is not particularly limited as long as the polyhydric alcohol, polycarboxylic acid, and hydroxycarboxylic acid, which are the constituent components of the polyester resin, are aliphatic polyhydric alcohol, aliphatic polycarboxylic acid, and aliphatic hydroxycarboxylic acid, respectively. However, aliphatic polyesters obtained from constituent components containing a polyhydric alcohol and a polycarboxylic acid are preferred in that the effects of the present application can be more easily obtained. Examples of aliphatic polyhydric alcohols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, propylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, neopentyl glycol (2,2-dimethylpropane-1,3-diol), 1,2-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,2-bis(4-hydroxycyclohexyl)propane, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, trimethylolpropane, glycerin, pentaerythritol, etc. These aliphatic polyhydric alcohols may be used alone or in combination of two or more.

[0020] Examples of aliphatic polycarboxylic acids include succinic acid, adipic acid, suberic acid, sebacic acid, azelaic acid, octyl succinic acid, fumaric acid, maleic acid, itaconic acid, decamethylene dicarboxylic acid, and anhydrides thereof. These aliphatic polycarboxylic acids may be used alone or in combination of two or more. Examples of aliphatic hydroxycarboxylic acids include lactic acid, glycolic acid, hydroxybutyric acid, hydroxycaproic acid, hydroxydimethylbutyric acid, and hydroxymethylbutyric acid. These aliphatic hydroxycarboxylic acids may be used alone or in combination of two or more.

[0021] Examples of aliphatic polyester resins include polycaprolactone butylene succinate, polybutylene succinate, polybutylene succinate adipate, polybutylene succinate carbonate, polybutylene adipate, polybutylene succinate lactate, polyethylene succinate, polyethylene adipate, polytetramethylene succinate, polyhydroxyalkanoate, polyhydroxybutyrate, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), polyhydroxybutyrate valerate, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyacyl), polyhydroxyacyl, and polylactic acid.

[0022] The aliphatic-aromatic polyester resin is not particularly limited as long as the polyhydric alcohol, polycarboxylic acid, and hydroxycarboxylic acid, which are the constituent components of the polyester resin, respectively contain the aliphatic polyhydric alcohol, aliphatic polycarboxylic acid, and aliphatic hydroxycarboxylic acid, and further contain an aromatic polycarboxylic acid or a derivative thereof. Examples of aromatic polycarboxylic acids include o-phthalic acid, terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, trimellitic acid, and pyromellitic acid. From the viewpoint of biodegradability, the proportion of aromatic polycarboxylic acid-derived components in the constituent components of the aliphatic-aromatic polyester resin is preferably 40 unit mol% or less. These aromatic polycarboxylic acids may be used alone or in combination of two or more.

[0023] Examples of the aliphatic-aromatic polyester resin include polybutylene succinate terephthalate, polybutylene adipate terephthalate, polytetramethylene adipate terephthalate, and polybutylene succinate adipate terephthalate.

[0024] The polyester resin preferably contains a biodegradable resin, and more preferably is a biodegradable resin, in that the polyester resin is an environmentally friendly material.

[0025] The proportion of polyester resin in the resin particles of the present invention is not particularly limited, but is preferably 30 to 100% by weight, as this facilitates achieving the loose bulk density of the present invention. The lower limit of this weight percentage is (1) 35% by weight, (2) 40% by weight, (3) 45% by weight, (4) 50% by weight, (5) 55% by weight, (6) 60% by weight, (7) 65% by weight, (8) 70% by weight, (9) 75% by weight, (10) 80% by weight, (11) 85% by weight, and (12) 90% by weight, in that order (the larger the value in parentheses, the more preferable it is). Furthermore, for example, 40 to 100% by weight is more preferable, 50 to 100% by weight is even more preferable, 80 to 100% by weight is particularly preferable, and 90 to 100% by weight is most preferable.

[0026] The polyester resin is not particularly limited, but may be a polyester resin having a weight average molecular weight of 5×10 ３ ~1 x 10 ９ The lower limit of the average molecular weight is (1) 1 × 10 ４ , (2) 2 × 10 ４ , (3) 3 × 10 ４ , (4) 5 × 10 ４ , (5) 1 × 10 ５ , (6) 2 × 10 ５ , (7) 3 × 10 ５ On the other hand, the upper limit of the average molecular weight is (1) 5 × 10 ８ (2) 3 x 10 ８ , (3) 1 × 10 ８ , (4) 5 × 10 ７ , (5) 3 × 10 ７ , (6) 1 × 10 ７ (The larger the value in parentheses, the more preferable it is.) Furthermore, for example, 2 × 10 ４ ~5 x 10 ８ is more preferable, and 3×10 ４ ~5 x 10 ８ is more preferable.

[0027] The resin particles of the present invention have a relative density of 0.6 g / cm ３In order to facilitate the preparation of the following, the composition may contain thermoplastic resins and thermosetting resins other than polyester resins (hereinafter sometimes referred to as "other resins"), organic polymers, surfactants, organic substances other than organic polymers, and inorganic substances, etc. Examples of other resins include thermoplastic resins such as polyvinyl resins, polyether resins, polyamide resins, thermoplastic polyurethane resins, cellulose resins, polyacrylic resins, polystyrene resins, and polyolefin resins; and thermosetting resins such as silicone resins, phenolic resins, unsaturated polyester resins, epoxy resins, melamine resins, and rubber, and one or more of these may be used in combination. Examples of organic polymers include paraffins, silicone oils, polyalkylene oxides, and water-soluble polymers, and examples thereof include paraffins such as liquid paraffin; silicone oils such as dimethyl silicone; polyalkylene oxides such as polyethylene oxide and polypropylene oxide; and water-soluble polymers such as sodium polyacrylate, polyvinylpyrrolidone, polyvinyl alcohol, dextrin, sodium alginate, potassium alginate, gum arabic, tamarind gum, pectin, pullulan, casein, xanthan gum, carrageenan, tragacanth gum, gelatin, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, carboxymethyl cellulose, and carboxyethyl cellulose, and these may be used alone or in combination of two or more.

[0028] Examples of surfactants include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, and silicone surfactants. Specific examples include anionic surfactants such as alkyl sulfates, alkyl ether carboxylates, alkyl ether sulfates, alkyl phosphates, polyoxyalkylene alkyl ether acetates, alkyl sulfonates, alkylbenzene sulfonates, polyoxyalkylene alkyl ether sulfates, polyoxyalkylene alkyl ether phosphates, higher fatty acid amide sulfonates, fatty acid alkali metal salts (e.g., potassium laurate, sodium myristate, sodium stearate), alkyl sulfosuccinates, and N-acylamino acid salts; cationic surfactants such as quaternary ammonium salts and alkylamine salts; and polyoxyalkylene oxide-adducted alkyl nonionic surfactants such as ethers, polyoxyalkylene styrenated phenyl ethers, ester compounds of polyhydric alcohols and monovalent fatty acids, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyalkylene castor oil, polyoxyalkylene hydrogenated castor oil, higher fatty acid PEG glyceryls, higher fatty acid sorbitans, polyoxyalkylene sorbitol fatty acid esters, polyglycerin fatty acid esters, alkyl glycerin ethers, polyoxyalkylene cholesteryl ethers, alkyl polyglucosides, sucrose fatty acid esters, and polysorbates; amphoteric surfactants such as amino acid-based surfactants, betaine-type surfactants, hydrogenated lecithin, and lecithin; and silicone-based surfactants such as modified silicones, and the like may be used alone or in combination of two or more thereof.

[0029] As organic substances other than organic polymers, the relative density is 0.6 g / cm ３Examples of waxes, oils, fatty acid metal salts, and amino acid compounds that are easy to adjust include waxes such as carnauba wax, candelilla wax, beeswax, and higher alcohols; oils such as almond oil, olive oil, rice bran oil, squalane, mineral oil, alkanes, and alkyl benzoates; fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, behenic acid, montanic acid, and cerotic acid; calcium laurate, zinc laurate, zinc myristic acid, zinc palmitate, magnesium stearate, zinc stearate, calcium stearate, aluminum stearate, calcium 12-hydroxystearate, and 12-hydroxystearic acid. fatty acid metal salts such as zinc hydroxystearate, magnesium 12-hydroxystearate, aluminum 12-hydroxystearate, calcium behenate, zinc behenate, magnesium behenate, calcium montanate, zinc montanate, magnesium montanate, and aluminum montanate; and amino acid compounds such as N-lauroyl-L-arginine, N-lauroyl-L-lysine, N-hexanoyl-L-lysine, N-oleyl-L-lysine, N-palmitoyl-L-lysine, N-stearanoyl-L-lysine, N-hexanoyl-L-lysine, N-myristonoyl-L-lysine, N-capryloyl-L-lysine, and N-decanoyl-L-lysine, and the like, and these may be used alone or in combination of two or more.

[0030] Examples of inorganic substances that can easily adjust the hiding power to 50% or less include wollastonite, sericite, kaolin, mica, clay, talc, bentonite, smectite, alumina silicate, pyrophyllite, montmorillonite, calcium silicate, calcium carbonate, magnesium carbonate, dolomite, calcium sulfate, calcium phosphate, boron nitride, silicon carbide, magnesium silicate, calcium silicate, magnesium aluminometasilicate, magnesium aluminosilicate, hydroxyapatite, titanium oxide, silica, alumina, titanium dioxide, zinc oxide, magnesium oxide, zinc oxide, hydrosaltite, and boron nitride, and these may be used alone or in combination of two or more.

[0031] The resin particles of the present invention are not particularly limited, but preferably have a biodegradability of 1% or more after 10 days as measured in accordance with JIS K6950: 2000. The lower limit of the biodegradability is more preferred in the following order (1) 3%, (2) 5%, (3) 10%, (4) 15%, (5) 20%, (6) 25%, and (7) 30% (the larger the number in parentheses, the more preferred it is).

[0032] [Method for producing resin particles] The resin particles of the present invention can be produced by a method including, for example, step 1 of mixing the above-mentioned polyester resin, a surfactant, a water-soluble polymer, and water to obtain a pre-mixed liquid, step 2 of heating and stirring the pre-mixed liquid obtained in step 1 to obtain a heated dispersion liquid, step 3 of cooling the heated dispersion liquid obtained in step 2, and step 4 of applying an external force to the obtained resin particle dispersion liquid to deform the particles.

[0033] Furthermore, in the resin particles of the present invention, it is preferable to produce them without using an organic solvent, since this allows for the production of resin particles with excellent transparency. If an organic solvent is used, pores tend to form in the resin particles when the organic solvent is removed from the resin particles, resulting in poor transparency of the resulting resin particles. Furthermore, by producing resin particles using water without using an organic solvent, it is believed that surfactants and water-soluble polymers are more likely to be present at the interface between the resin particles and water during resin particle formation, which contributes to the surface shape of the resin particles. Furthermore, it is believed that the lipophilic groups of the surfactant affect the resin structure, resulting in resin particles with excellent transparency. Furthermore, not using an organic solvent is environmentally friendly and preferable.

[0034] The surfactant is not particularly limited, but can be appropriately selected depending on the components constituting the resin particles so as to achieve the effects of the present invention. The surfactants described above can be used. The surfactant is not particularly limited, but using at least one selected from anionic surfactants and nonionic surfactants is preferred because it improves the stability of the polyester resin dispersion in water, and using a nonionic surfactant is more preferred because it makes it easier to adjust the hiding power to 50% or less. The nonionic surfactant is not particularly limited, but is preferably an ester compound of a polyhydric alcohol and a monovalent fatty acid, and more preferably at least one selected from glycerin fatty acid esters and higher fatty acid sorbitans. The surfactant is not particularly limited, but using a nonionic surfactant with an HLB value of 1 to 13 is preferred because it makes it easier to adjust the hiding power of the resin particles to 50% or less. Furthermore, using an ester or ester salt surfactant is preferred because it provides excellent particle transparency. The HLB value can be calculated, for example, using the following Griffin formula (4): HLB = 20 × (molecular weight of hydrophilic group / total molecular weight) (4)

[0035] The surfactant may be ultimately contained in the particles. The presence of the surfactant near the particle surface is thought to have a greater effect on the surface structure, and the increased compatibility with water makes it easier to wash off when it adheres to equipment. The weight ratio of the surfactant in the particles is not particularly limited, but is preferably 0.001 to 10 wt %, with the upper limit of the weight ratio being more preferably 7 wt %, and even more preferably 5 wt %. Meanwhile, the lower limit of the weight ratio is more preferably 0.005 wt %, and even more preferably 0.01 wt %. Furthermore, for example, 0.001 to 7 wt % is more preferable, and 0.001 to 5 wt % is even more preferable.

[0036] The water-soluble polymer can be any of those described above. From the viewpoint of stably obtaining resin particles containing the polyester resin of the present invention, a water-soluble polymer having a viscosity of 2 to 200,000 mPa·s in a 4% aqueous solution at 20°C is preferred. The water-soluble polymer is preferably at least one selected from polyvinylpyrrolidone, polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, and carboxymethyl cellulose, with polyvinyl alcohol being more preferred. The water-soluble polymer may be ultimately contained in the particles. The presence of the water-soluble polymer in the particles is considered preferable in that it enhances affinity with solvents such as water, making it easier to adjust the hiding power to 50% or less. The weight percentage of the water-soluble polymer in the particles is not particularly limited, but is preferably 0.001 to 10 wt%, with the upper weight percentage being more preferably 8 wt%, and even more preferably 5 wt%. Meanwhile, the lower weight percentage is more preferably 0.002 wt%, and even more preferably 0.005 wt%. Furthermore, for example, 0.001 to 8% by weight is more preferable, and 0.001 to 5% by weight is even more preferable.

[0037] The resin particles of the present invention preferably contain at least one surfactant and a water-soluble polymer, as this enhances their affinity with solvents such as water. The total weight percentage of the surfactant and water-soluble polymer in the particles is not particularly limited, but is preferably 0.001 to 10 wt%. The lower limit of this weight percentage is more preferred in the following order (1) 0.002 wt%, (2) 0.005 wt%, (3) 0.01 wt%, (4) 0.02 wt%, (5) 0.05 wt%, and (6) 0.1 wt% (the larger the value in parentheses, the more preferred it is). Meanwhile, the upper limit of this weight percentage is more preferred in the following order (1) 7 wt%, (2) 6 wt%, (3) 5 wt%, (4) 4 wt%, and (5) 3 wt% (the larger the value in parentheses, the more preferred it is). Furthermore, for example, 0.001 to 7 wt% is more preferred, and 0.001 to 5 wt% is even more preferred.

[0038] When the resin particles of the present invention are produced by mixing a surfactant and a water-soluble polymer, the water-soluble polymer improves the liquid viscosity during production, the surfactant improves the efficiency of particle homogenization, and the surfactant improves the dispersibility of the resin component, thereby resulting in stable resin particles. Therefore, it is even more preferable that the weight ratios of the surfactant and the water-soluble polymer are within the above-mentioned ranges.

[0039] (Step 1) Step 1 is a step of mixing a polyester resin, a surfactant, a water-soluble polymer, and water to obtain a preliminary mixed solution. When the resin particles contain components other than the polyester resin, the surfactant, and the water-soluble polymer, the other components may be added and mixed in this step.

[0040] In step 1, the mixing ratio of the polyester resin is not particularly limited, but is preferably 1 to 200 parts by weight per 100 parts by weight of water. A ratio within this range tends to produce resin particles with a more uniform shape, which is preferable because it makes it easier to satisfy the circularity requirement of the present invention and therefore makes it easier to obtain the particle size of the present invention. The lower limit of the mixing ratio is more preferably 3 parts by weight, even more preferably 5 parts by weight, and most preferably 10 parts by weight. Meanwhile, the upper limit of the mixing ratio is more preferably 180 parts by weight, even more preferably 160 parts by weight, and most preferably 150 parts by weight. Furthermore, for example, 5 to 200 parts by weight is more preferable, and 10 to 180 parts by weight is even more preferable.

[0041] In step 1, the mixing ratio of the surfactant is not particularly limited, but is preferably 0.001 to 10 parts by weight per 100 parts by weight of the polyester resin, as this facilitates obtaining the particle diameter of the present invention. A ratio within this range tends to improve the transparency of the resulting resin particles, which is preferable in that it is easy to adjust the hiding ratio to 50% or less. The lower limit of the mixing ratio is preferably 0.01 parts by weight, more preferably 0.05 parts by weight, and particularly preferably 0.1 parts by weight. The upper limit of the mixing ratio is more preferably 7 parts by weight, even more preferably 5 parts by weight, and particularly preferably 3 parts by weight. Furthermore, for example, 0.001 to 7 parts by weight is more preferable, and 0.01 to 7 parts by weight is even more preferable.

[0042] In step 1, the mixing ratio of the water-soluble polymer to water is not particularly limited, but is preferably 0.1 to 100 parts by weight per 100 parts by weight of water, since this facilitates stable production of the polyester resin particles of the present invention. A ratio within this range tends to improve the dispersibility of the resulting resin particles, which is preferable since it facilitates satisfying the circularity requirement of the present invention. The lower limit of this ratio is more preferably 0.5 parts by weight, even more preferably 1 part by weight, and particularly preferably 2 parts by weight. Meanwhile, the upper limit of this ratio is more preferably 80 parts by weight, even more preferably 70 parts by weight, and particularly preferably 60 parts by weight. Furthermore, for example, a ratio of 0.5 to 100 parts by weight is more preferable, and 1 to 100 parts by weight is even more preferable.

[0043] (Step 2) Step 2 is a step in which the pre-mixed liquid obtained in Step 1 is heated and stirred to obtain a heated dispersion. The pressure during heating and stirring in Step 2 is not particularly limited, but is preferably 0.1 to 10 MPa. It is preferable that the pressure is equal to or greater than the saturated vapor pressure of water at the heating temperature. The heating temperature is not particularly limited, but is preferably 80 to 200°C. A temperature within the above range tends to result in more uniformly shaped resin particles, making it easier to stably obtain particle sizes within the target range of the present invention and satisfy the loose bulk density of the present invention. The temperature is preferably equal to or greater than the softening point or melting point of the polyester resin, more preferably at least 10°C higher than the softening point or melting point of the polyester resin, even more preferably at least 20°C higher, and particularly preferably at least 30°C higher. Furthermore, in Step 2, heating to a temperature equal to or greater than the softening point or melting point of the polyester resin and stirring under a pressure of 0.1 MPa or higher is preferable, as this makes it easier to satisfy the circularity requirement of the present invention.

[0044] The stirring method is not particularly limited, but it is sufficient that the mixture is stirred to the extent that it is mixed. The heating time is not particularly limited, but is preferably 1 to 30 hours. If the time is 1 hour or more, more uniform dispersion occurs, and the particle size of the present invention is easily obtained, which is preferable. If the time is 30 hours or less, production efficiency tends to improve. The lower limit of the time is more preferably 2 hours, even more preferably 3 hours, and most preferably 5 hours. The upper limit of the heating time is more preferably 25 hours, even more preferably 20 hours, and most preferably 15 hours.

[0045] (Step 3) Step 3 is a step of cooling the heated dispersion obtained in step 2. By cooling the heated dispersion of step 2, a dispersion of resin particles can be obtained. The cooling method is not particularly limited, but it is preferable to cool the heated dispersion obtained in step 2 to 5 to 50°C. The cooling rate is not particularly limited, but rapid cooling or natural cooling by air cooling or the like may be used. In step 3, stirring may be performed at the stirring speed of step 2, or stirring may be stopped. The dispersion after cooling is an aqueous dispersion containing resin particles.

[0046] (Step 4) Step 4 is a step of applying a mechanical external force to the resin particles obtained in step 3 to deform the resin particles. By applying a mechanical external force to the resin particles obtained in step 3, resin particles having the loose bulk density of the present invention can be efficiently obtained. The deformation method is not particularly limited, but a method of applying a physical force to the particles is preferable because it is easier to satisfy the circularity of the present invention. The method of applying the mechanical external force is not particularly limited, but examples include mixing and stirring with glass beads, a ball mill, a bead mill, and a vibration dryer. The form of the resin particles in step 4 may be a dispersion, a wet powder, or a dry powder.

[0047] The resin particles of the present invention may be used in the form of a dispersion, a wet powder, or a dry powder. The wet powder can be obtained by dehydrating the dispersion of Step 3 using, for example, a centrifuge, a pressure press, a vacuum dehydrator, or the like. The dispersion of Step 3 may be dehydrated after a measure to reduce the liquid viscosity has been taken. Methods for reducing the liquid viscosity include, but are not limited to, diluting the liquid by adding water, salting out the water-soluble components, and decomposing the water-soluble components with an oxidizing agent or enzyme. The liquid viscosity is not particularly limited as long as the dehydration treatment can be carried out. However, the viscosity is preferably 1,000 mPa·s or less, more preferably 500 mPa·s or less, and particularly preferably 100 mPa·s or less, from the viewpoints of suppressing aggregation of the resin particles in the subsequent drying step and easily adjusting the hiding power to 50% or less. The dry powder can be obtained by drying the wet powder using a tray dryer, an indirect heating dryer, a fluidized bed dryer, a vacuum dryer, a vibration dryer, a flash dryer, or the like. Alternatively, the dispersion obtained in step 3 may be dried using a spray dryer, fluidized bed dryer, or the like to obtain a dry powder. The dry powder may be classified by air classification, screen classification, or the like.

[0048] [Uses of Resin Particles] The resin particles of the present invention can be used in cosmetics, paints, optical applications, resins, building materials, etc. In particular, the resin particles of the present invention are excellent in transparency and can therefore be suitably used in cosmetics and coating compositions.

[0049] When the resin particles of the present invention are incorporated into cosmetics, the resulting cosmetics have a natural finish and can also provide a pleasant feel. When used in cosmetics, the resin particles can be used in combination with known cosmetic ingredients. Examples of cosmetic ingredients include oils, surfactants, alcohols, water, moisturizers, gelling agents, thickeners, powders other than the resin particles of the present invention, UV absorbers, preservatives, antibacterial agents, antioxidants, and functional ingredients. Cosmetics incorporating the resin particles of the present invention may be in the form of powder, solid, cream, gel, liquid, mousse, spray, or the like. The weight percentage of the resin particles relative to the total cosmetic is not particularly limited, but is preferably 0.1 to 50 wt %, more preferably 0.5 to 30 wt %, and even more preferably 1 to 20 wt %.

[0050] When the resin particles of the present invention are blended into a coating composition, transparency can be maintained. When used in a coating composition, they can be used in combination with known coating components. The weight ratio of the resin particles to the entire coating composition is not particularly limited, but is preferably 0.1 to 30 wt %, more preferably 0.5 to 20 wt %, and even more preferably 1 to 10 wt %.

[0051] Examples of the resin particles of the present invention will be specifically described below. However, the present invention is not limited to these examples. Furthermore, the particles shown in the examples and comparative examples were measured for physical properties and further evaluated in the following manner.

[0052] (Measurement of Volume Average Particle Diameter) Measurement was carried out using a laser diffraction scattering particle size distribution measuring device (Microtrac particle size distribution meter (model 9320-HRA), manufactured by Nikkiso Co., Ltd.) by irradiating with ultrasonic waves for 120 seconds by a wet measurement method. The volume average particle diameter was adopted as the value (D50) at which the cumulative frequency in the volume-based measurement was 50%.

[0053] (Measurement of Average Circularity) The average circularity was calculated using a dynamic particle image analyzer (Hydro Insight, manufactured by Spectris). Specifically, the measurement method involved adding 200 mg of a resin particle sample to a beaker containing 20 mL of ion-exchanged water and treating it in an ultrasonic bath for 1 minute to obtain a sample solution. Water was circulated at 2500 rpm in advance in the Hydro MV dispersion unit of the Mastersizer 3000 to which the Hydro Insight was connected, and the sample solution was added until a predetermined concentration was reached, and measurement was performed. (Measurement Conditions) Lens: Standard lens (particle size measurement range: 1 to 300 μm) Camera gain: 50 Dark threshold: 80 Min sharpness: 30 Number of particles measured: 10,000

[0054] (Measurement of Oil Absorption) Measurement was carried out using linseed oil according to the method for measuring linseed oil absorption specified in JIS-K5101-13-1.

[0055] (Measurement of apparent specific gravity) The weight a of a 100 mL volumetric flask was measured, and then 1 g of sample was added to the volumetric flask and weight b was measured. Isopropyl alcohol was added to this exactly up to the 100 mL mark, and the total weight c was measured. Separately, the empty weight x of the volumetric flask was measured, and isopropyl alcohol was added to this exactly up to the mark, and the total weight y was measured. From these measured values, the apparent specific gravity was calculated using the following formula (5). Apparent specific gravity = (b - a) × (y - x) / {100 × [(y - x) - (c - b)]} (5) Using this measurement method, the apparent specific gravity of the resin particles was measured.

[0056] (Measurement of Concealment Ratio) Based on the opacity test paper method described in JIS K 5600-4-1:1999, the concealment ratio was measured by the following procedure. The coating mixture used for evaluation was prepared as follows: Binder resin: 70 parts by weight of urethane water-based gloss paint for buildings (manufactured by Sunday Paint, model number Sunday-037902) Resin particles: 30 parts by weight The prepared coating mixture was applied to an opacity test paper (vertical black and white A type) so that the coating thickness after drying would be 100 μm to prepare a sample. The transparency of the measured sample was calculated using a color difference meter CR-400 manufactured by Konica Minolta Inc., using the whiteness of the black part (WIb) and the whiteness of the white part (WIw) before coating, and the whiteness of the black part (WI) after coating, using the following formula: Concealment ratio (%) = (WI - WIb) / (WIw - WIb) x 100

[0057] (Measurement of loose bulk density) The loose bulk density of the obtained resin particles was measured using a multi-function powder property measuring instrument (Multitester MT-1001K) manufactured by Seishin Enterprises. Specifically, in accordance with JIS K 6219-2 (2005), a stainless steel cup with an inner diameter of φ50 mm and an internal volume (V) of 100 cc was prepared, and its weight (Wb) was measured. Resin particles passed through a JIS 24 mesh sieve were uniformly added to the stainless steel cup from above (23 cm) and supplied to the upper edge of the stainless steel cup. The resin particles were then leveled off at the top of the stainless steel cup, and the weight (Wa) of the stainless steel cup containing the resin particles was measured. The loose bulk density (ρa) was calculated using the following formula: ρa = (Wa - Wb) / V

[0058] (Calculation of Relative Density) In this application, the relative density is the mass of resin particles contained in a unit volume compared with the apparent specific gravity, which is the theoretical specific gravity of the material. The relative density was calculated using the following formula: relative density (g / cm ３ ) = loose bulk density (g / cm ３ A higher relative density (apparent specific gravity) indicates that the resin particles are packed closer to the theoretical maximum density, and a lower relative density indicates that many voids exist between the resin particles.

[0059] (Evaluation of Cleanability) In this application, the evaluation of cleanability is an index showing the ease of cleaning resin particles adhering to equipment, etc. The evaluation of cleanability was performed under the following conditions. The better the cleanability, the better the cleanability of resin particles adhering to equipment. (1) Sample Preparation: 1 g of resin particles was dispersed in 10 g of water and placed in a 10 mL centrifuge tube. The centrifuge tube was then shaken up and down 30 times or more to obtain a uniform aqueous dispersion of resin particles. (2) Setting: The sample prepared in (1) was settling for 24 hours. During this setting, the resin particles naturally settled and aggregated at the bottom of the container. (3) Evaluation: After setting, the container was turned upside down 10 times once per second, and the state of the resin particles in the container was then confirmed. The ease of cleaning of the resin particles was evaluated. ⊚: The resin particles were quickly dispersed by vibrating the container, and the ease of cleaning was excellent. ◯: The resin particles are dispersed by vibrating the container, and cleaning is easy. △: Even when the container is vibrated, only some of the resin particles are dispersed, and cleaning is poor. ×: Even when the container is vibrated, the resin particles are not dispersed, and cleaning is significantly poor.

[0060] Example 1 300 parts by weight of water, 100 parts by weight of polybutylene succinate adipate, 0.5 parts by weight of sorbitan monolaurate, and 20 parts by weight of polyvinyl alcohol were mixed and placed in a 1 L pressure-resistant container and sealed. The internal temperature of the container was raised to 130 ° C., and the mixture was stirred at 250 rpm for 5 hours under a pressure of 0.4 MPa. The mixture was then cooled to 30 ° C. and an oxidizing agent was added to obtain an aqueous dispersion of approximately spherical resin particles (1). The obtained aqueous dispersion of approximately spherical resin particles (1) was transferred to a 1 L glass beaker, and 100 parts by weight of water and 1,000 parts by weight of glass beads with a diameter of 5 mm were added. The mixture was mixed at 30 ° C. and atmospheric pressure at a speed of 300 rpm for 12 hours using a Three-One motor equipped with an anchor blade (blade diameter 20 mm) to obtain an aqueous dispersion of flat resin particles (1). The obtained aqueous dispersion (1) was dehydrated by filtration, dried at 50°C, and classified to obtain flat resin particles 1. The evaluation results of the obtained resin particles 1 are shown in Table 1. An electron microscope photograph of resin particles 1 is shown in Figure 1. Resin particles 1 contained 98.8% by weight of polyester resin, 0.2% by weight of sorbitan monolaurate, and 1.0% by weight of polyvinyl alcohol.

[0061] [Example 2] Flat resin particles 2 were obtained in the same manner as in Example 1, except that the processing time for the step of deforming the resin particles was changed to 6 hours. The resin particles 2 contained 98.8% by weight of polyester resin, 0.3% by weight of sorbitan monostearate, and 0.9% by weight of polyvinyl alcohol.

[0062] [Example 3] Flat resin particles 3 were obtained in the same manner as in Example 1, except that the treatment time for the step of deforming the resin particles was changed to 18 hours. The polyester resin contained in particles 3 was 99.1% by weight, sorbitan monolaurate was 0.1% by weight, and polyvinyl alcohol was 0.8% by weight.

[0063] Example 4 An aqueous dispersion (4) of approximately spherical resin particles was obtained in the same manner as in Example 1, except that polybutylene succinate adipate was replaced with polybutylene succinate. The obtained aqueous dispersion (4) of approximately spherical resin particles was treated for 24 hours using a bead mill (Dyno Mill Multilab 0.6, manufactured by Shinmaru Enterprises) whose casing was filled with zirconia beads having a diameter of 0.3 mm, to obtain an aqueous dispersion (4) of flat resin particles. The obtained aqueous dispersion (4) was dehydrated by filtration, dried at 50°C, and classified to obtain flat resin particles 4. Furthermore, particles 4 contained 99.4 wt% polyester resin, 0.1 wt% sorbitan monolaurate, and 0.5 wt% polyvinyl alcohol.

[0064] Example 5 An aqueous dispersion (5) of roughly spherical resin particles was obtained in the same manner as in Example 1, except that polybutylene succinate adipate was replaced with polybutylene adipate terephthalate and 0.3 g of sorbitan monolaurate was used. The obtained aqueous dispersion (5) of roughly spherical resin particles was dehydrated by filtration, dried at 50°C, and classified to obtain roughly spherical resin particles (5). 50 parts by weight of the obtained roughly spherical resin particles (5) was added to a 500 mL stainless steel pot mill, to which 100 g of water and 500 parts by weight of glass beads with a diameter of 5 mm were added, and the mixture was mixed at 30°C and atmospheric pressure at 150 rpm using a benchtop ball mill (Model V-1, manufactured by Irie Shokai) for 6 hours to obtain a water dispersion (5) of flattened resin particles. The obtained aqueous dispersion (5) was dehydrated by filtration, dried at 50°C, and classified to obtain flattened resin particles 5. The content of polyester resin in particle 5 was 100% by weight, the content of sorbitan monolaurate was 0% by weight, and the content of polyvinyl alcohol was 0% by weight.

[0065] [Example 6] Flat resin particles 6 were obtained in the same manner as in Example 1, except that polybutylene succinate adipate was changed to polytetramethylene adipate terephthalate and the amount of sorbitan monolaurate was changed to 0.25 g. The polyester resin contained in particles 6 was 98.8 wt%, the sorbitan monolaurate was 0.3 wt%, and the polyvinyl alcohol was 0.9 wt%.

[0066] [Example 7] Flat resin particles 7 were obtained in the same manner as in Example 1, except that the amount of polybutylene succinate adipate was changed from 100 parts by weight to 70 parts by weight, and the amount of polyhydroxyalkanoate was changed to 30 parts by weight. Resin particles 7 contained 98.5% by weight of polyester resin, 0.4% by weight of sorbitan monolaurate, and 1.1% by weight of polyvinyl alcohol.

[0067] [Example 8] Flat resin particles 8 were obtained in the same manner as in Example 1, except that the amount of polybutylene succinate adipate was changed from 100 parts by weight to 20 parts by weight and the amount of low-density polyethylene was changed to 80 parts by weight. Resin particles 8 contained 19.7% by weight of polyester resin, 78.6% by weight of low-density polyethylene, 0.5% by weight of sorbitan monolaurate, and 1.2% by weight of polyvinyl alcohol.

[0068] [Example 9] Flat resin particles 9 were obtained in the same manner as in Example 1, except that the 100 parts by weight of polybutylene succinate adipate in Example 1 was changed to 90 parts by weight and the calcium carbonate was changed to 10 parts by weight. Resin particles 9 contained 88.9% by weight of polyester resin, 9.9% by weight of calcium carbonate, 0.2% by weight of sorbitan monolaurate, and 1.0% by weight of polyvinyl alcohol.

[0069] Comparative Example 1 Approximately spherical resin particles 10 were obtained in the same manner as in Example 1, except that the step of deforming the particles with glass beads was omitted.

[0070] Comparative Example 2 Matsumoto Microsphere MHB-R (manufactured by Matsumoto Yushi Seiyaku Co., Ltd., average particle size 11 μm), which is PMMA crosslinked hollow particles, was used as the resin particles.

[0071] Comparative Example 3 30 parts by weight of polybutylene succinate adipate and 970 parts by weight of 3-methoxy-3-methyl-1-butanol were mixed and placed in a 1 L pressure vessel, which was then sealed. The temperature inside the vessel was raised to 140°C, and the mixture was stirred at 400 rpm for 2.0 hours under a pressure of 0.1 MPa and then cooled to 25°C to obtain a dispersion of resin particles. The mixture was then dehydrated by filtration and dried at 50°C to obtain porous resin particles 3.

[0072] Comparative Example 4 Flat resin particles 11 were obtained in the same manner as in Example 1, except that the amount of polybutylene succinate adipate was changed from 100 parts by weight to 60 parts by weight and calcium carbonate was changed to 40 parts by weight.

[0073]

[0074] The particles of Examples 1 to 9 contain a polyester resin, have a circularity of 0.9 or less, and a loose bulk density of 0.1 to 0.5 g / cm ３ On the other hand, the particles of Comparative Examples 1 to 4 were not particles of the present invention, and therefore were difficult to wash off when they adhered to equipment, resulting in a decrease in the efficiency of the manufacturing process.

[0075] The resin particles of the present invention can be easily washed away, which increases production efficiency, reduces waste, and cuts facility maintenance costs.

Claims

1. Resin particles containing polyester resin, with an average circularity of 0.9 or less and a loose bulk density of 0.1 to 0.5 g / cm³. ３ Resin particles having a linseed oil absorption capacity of 150-500 ml / 100 g.

2. The resin particles according to claim 1, wherein the opacity rate is 50% or less.

3. The resin particle according to claim 1, wherein the average circularity is the average circularity measured by dynamic image analysis.

4. The resin particles according to claim 1, wherein the apparent specific gravity is 2.0 or less.

5. The relative density shown in the following formula (1) is 0.6 g / cm³. ３ The resin particles according to claim 1, which are as follows: Relative density (g / cm³) ３ ) = loose bulk density (g / cm³) ３ ) ÷ apparent specific gravity ... (1)

6. A composition comprising resin particles according to any one of claims 1 to 5.

7. A cosmetic composition comprising resin particles according to any one of claims 1 to 5.

8. A coating composition comprising resin particles according to any one of claims 1 to 5.