Urethane resin powder

Abstract

Provided is a urethane resin powder containing urethane resin particles containing a urethane resin, the urethane resin powder being characterized in that: the average circularity of the urethane resin particles contained in the urethane resin powder is 0.950 or more; the stress when the urethane resin particles are compressed by 10% of the particle diameter in an environment of 23°C and 50% RH is 0.25-0.50 mN; and the glass transition temperature of the urethane resin particles is 0°C or lower.

Description

urethane resin powder

[0001] The present invention relates to a urethane resin powder containing urethane resin particles that is blended into paints, cosmetics, surface modifiers for synthetic leather, and the like.

[0002] Urethane resin particles, which are primarily composed of polyurethane resin, have excellent hardness properties, such as flexibility and scratch resistance, in addition to solvent resistance and heat resistance, and are therefore widely used as surface modifiers for paints, adhesives, cosmetics, and synthetic leather, as well as fillers for plastic and rubber products. From the standpoint of the feel and flexibility of products using the urethane resin particles, it is important to appropriately control the hardness of the urethane resin particles, and urethane resin particles with various controlled hardnesses are disclosed in Patent Documents 1 and 2.

[0003] JP 2007-4142 A JP 2018-35249 A

[0004] One of the important requirements for urethane particles is that their performance not change significantly with the season or the environment in which they are used, i.e., that their hardness not be affected by the environment. However, to date, no urethane resin particles have been found that have both a moderate hardness and a low environmental dependency. The object of the present invention is to provide a urethane resin powder containing urethane resin particles that have a moderate hardness and a low environmental dependency.

[0005] A urethane resin powder containing urethane resin particles containing a urethane resin, characterized in that the urethane resin particles contained in the urethane resin powder have an average circularity of 0.950 or more, a stress of 0.25 mN or more and 0.50 mN or less when the urethane resin particles are compressed by 10% of their particle size in an environment of 23°C and 50% RH, and a glass transition temperature of the urethane resin particles is 0°C or less.

[0006] It is possible to provide a urethane resin powder containing urethane resin particles that has an appropriate hardness and is less dependent on the environment.

[0007] In the present disclosure, unless otherwise specified, the expressions "XX to YY" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined in any way.

[0008] The inventors have found that the above problem can be solved by controlling the stress of the urethane resin particles to 0.25 mN or more and 0.50 mN or less when compressed by 10% of their particle size in an environment of 23°C and 50% RH, and by controlling the glass transition temperature to 0°C or less.

[0009] The present disclosure relates to a urethane resin powder containing urethane resin particles containing a urethane resin, wherein the urethane resin particles contained in the urethane resin powder have an average circularity of 0.950 or more, a stress of 0.25 mN or more and 0.50 mN or less when compressed by 10% of their particle size in an environment of 23°C and 50% RH, and a glass transition temperature of the urethane resin particles is 0°C or less.

[0010] The present inventors believe that the mechanism by which the effects of the present invention are exhibited is as follows.

[0011] The urethane resin particles of the present invention have a glass transition temperature of 0°C or lower. That is, the urethane resin particles of the present invention are in a rubbery state in the temperature range used in practical applications. Ordinary resins are characterized by large changes in hardness in the transition region from a glassy state to a rubbery state and in the transition region from a rubbery state to a molten state. On the other hand, they are characterized by little change in hardness with temperature in the temperature range where they exist in a glassy or rubbery state without a state transition. The urethane resin particles of the present invention are in a rubbery state in the commonly used temperature range of 10°C to 40°C, and therefore little change in hardness with temperature. That is, they are less environmentally dependent.

[0012] The composition of the urethane resin is also appropriately controlled so that the stress when the urethane resin particles are compressed to 10% of their particle size in an environment of 23°C and 50% RH is 0.25 mN or more and 0.50 mN or less, thereby achieving the urethane resin particles of the present invention that have both appropriate hardness and low environmental dependency, and ultimately the urethane resin powder containing them.

[0013] The urethane resin powder according to the present invention will be described in more detail below.

[0014] The average circularity of the urethane resin particles of the present invention is preferably 0.950 or more. Circularity here refers to a value representing the particle shape calculated from a projected image of the particle. First, a particle image is captured, its contour is extracted, and the projected area S and perimeter L of the particle image are measured. Next, the area S and perimeter L are used to determine the equivalent circle diameter and circularity. The equivalent circle diameter is the diameter of a circle having the same area as the projected area of ​​the particle image, and circularity C is defined as the value obtained by dividing the perimeter of the circle calculated from the equivalent circle diameter by the perimeter of the projected particle image, and is calculated using the following formula: Circularity C = 2 x (π x S) １／２ / L

[0015] After calculating the circularity of each particle, the range of circularity from 0.200 to 1.000 is divided into 800 parts, and the arithmetic mean value of the obtained circularities is calculated, and this value is taken as the average circularity.

[0016] When the particle image is circular, the circularity is 1, and the greater the degree of irregularity on the periphery of the particle image, the smaller the circularity value. In other words, a circularity close to 1 means that the shape is close to a perfect sphere.

[0017] The average circularity is preferably 0.950 or more. When the average circularity is 0.950 or more, variations in performance due to particle shape can be suppressed. The average circularity can be controlled by changing the type of monomer used or the production conditions.

[0018] The urethane resin particles of the present invention have a stress of 0.25 mN or more and 0.50 mN or less, preferably 0.26 mN or more and 0.38 mN or less, when compressed by 10% of their particle size in an environment of 23°C and 50% RH. In other words, this hardness range is the appropriate hardness that is the object of the present invention. The tactile area of ​​the human skin has a hardness of 10 to 10 ３ μN, unevenness resolution is 10 －２ ~10 ２ The appropriate hardness, which is the objective of the present invention, is within this range. In other words, when the urethane resin particles of the present invention are used, for example, as a surface modifier for synthetic leather, they can be endowed with the function of "minimal change in feel depending on the usage environment." The stress when compressed to 10% of the particle size can be adjusted by adjusting the type, molecular weight, and functionality of the monomers used in producing the urethane resin particles, the composition ratio of each monomer, the type of catalyst, the amount of solvent used, and the like.

[0019] The glass transition temperature (Tg) of the urethane resin particles of the present invention is 0°C or lower. If the Tg is greater than 0°C and less than 40°C, a transition between the glassy state and the rubbery state occurs within the practical temperature range, resulting in increased environmental dependency and preventing the achievement of the object of the present invention. Even when the Tg is controlled to a temperature higher than 40°C, the glassy state transition does not occur throughout the practical temperature range, thereby reducing environmental dependency. However, this method tends to result in a hardness that is higher than the hardness range of the present invention, which is undesirable.

[0020] The Tg of the urethane resin particles can be adjusted by the type, molecular weight, functionality, and composition ratio of each monomer used in producing the urethane resin particles, the type of catalyst, the amount of solvent used, and the like.

[0021] Among these, it is preferable to control Tg by using a compound having the formula (1) which will be described in detail later.

[0022] The Tg of the urethane resin particles is more preferably −20° C. or lower.

[0023] The urethane resin particles of the present invention are characterized in that, in pulse NMR measurement of the urethane resin powder at a measurement temperature of 23° C., hydrogen nuclei １ The spin-spin relaxation time T ２ Measurement is performed by a solid echo method to obtain an echo intensity curve A of the urethane resin powder. The echo intensity curve A is decomposed into three components by the least squares method, and the component with the shortest relaxation time among the three components is designated as component T. ２ｓ The component T in the urethane resin particles was designated as A. ２ｓ The component fraction of A is F ｓ When A [%] is used, F ｓ It is preferable that A is 15 or more and 90 or less.

[0024] The component T ２ｓ A is generally called "hard segment at 23°C", and components near the crosslinking points in the urethane resin that forms the urethane resin particles and components in which part of the molecular chain is oriented and stacked are included in component T. ２ｓ It is detected as A.

[0025] Ingredient T ２ｓ A component fraction F ｓ By controlling the component fraction F [%] within the above range, urethane resin particles with less environmental dependency can be obtained. ｓ A [%] is more preferably 25 or more and 60 or less, and further preferably 30 or more and 45 or less.

[0026] Component fraction F ｓ A [%] can be adjusted by the type, molecular weight, and functionality of the monomer used in producing the urethane resin particles. Specifically, F can be adjusted by using a monomer whose molecular chains are easily oriented and stacked, or by adding a polyfunctional monomer component. ｓ A [%] can be increased.

[0027] The urethane resin particles of the present invention have the following characteristics: (1) In pulse NMR measurement of the urethane resin powder at a measurement temperature of 10° C., hydrogen nuclei １ The spin-spin relaxation time T ２Measurement is performed by a solid echo method, an echo intensity curve B of the urethane resin powder is obtained, the echo intensity curve B is decomposed into three components by the least squares method, and the component with the shortest relaxation time among the three components is designated as component T ２ｓ B, and the component T in the urethane resin powder ２ｓ The component fraction of B is F ｓ B [%], and (2) in pulse NMR measurement of the urethane resin powder at a measurement temperature of 40°C, the hydrogen nuclei １ The spin-spin relaxation time T ２ Measurement is performed by a solid echo method, an echo intensity curve C of the urethane resin powder is obtained, the echo intensity curve C is decomposed into three components by the least squares method, and the component with the shortest relaxation time among the three components is designated as component T ２ｓ C, and the component T in the urethane resin powder ２ｓ The component fraction of C is F ｓ When C [%], F ｓ B / F ｓ C is preferably 1.0 or more and 1.5 or less.

[0028] The component T ２ｓ B is generally called a "hard segment at 10°C" and ２ｓ C is generally called "hard segment at 40°C." Component T in the urethane resin powder ２ｓ B, and component T ２ｓ C component fraction F ｓ B, and F ｓ Let C. Then, F ｓ F against C ｓ Ratio of B to F ｓ B / F ｓ The fact that C is small, between 1.0 and 1.5, means that the amount of components detected as hard segments does not change significantly depending on the temperature. Generally, hard segments due to molecular chain orientation and stacking tend to move easily due to heat. Therefore, F ｓ B / F ｓ The fact that C is small means that the component T detected as a hard segment ２ｓ B, and component T ２ｓIt is believed that most of C is a component near the crosslinking point.

[0029] F ｓ B / F ｓ C can be adjusted by the type, molecular weight, and functionality of the monomer used in producing the urethane resin particles. Among these, as described above, it is preferable to add a polyfunctional monomer in order to increase the components near the crosslinking points.

[0030] F ｓ B / F ｓ A more preferred range for C is less than 1.45, and even more preferably less than 1.40.

[0031] The urethane resin particles of the present invention contain the urethane resin as a main component.

[0032] The term "main component" as used herein means that the content is 50% or more by mass.

[0033] Within the scope of the present invention, materials other than urethane resin may be contained depending on various purposes, such as colorants such as dyes and pigments, ultraviolet absorbers, antioxidants, metal powders, and fragrances.

[0034] The urethane resin contained in the urethane resin particles of the present invention preferably has a partial structure represented by the following formula (1) in its molecular structure.

[0035]

[0036] By having such a structure, the orientation regularity of the urethane resin is significantly reduced, making it easier to control the glass transition temperature to 0° C. or less.

[0037] In order to incorporate the formula (1) into the molecular structure of the urethane resin, it is preferable to synthesize the urethane resin using an isocyanate component or polyol component having the structure of the formula (1) as a raw material. In particular, from the viewpoint of availability, it is preferable to use a polyol component having the structure of the formula (1).

[0038] Specific examples include polycarbonate polyols of 3-methyl-1,5-propanediol (MPD), polyester polyols of MPD and sebacic acid, polyester polyols of MPD and adipic acid, polyester polyols of MPD and terephthalic acid, and polyester polyols of MPD and isophthalic acid.

[0039] The method for synthesizing the urethane resin in the urethane resin particles of the present invention is not particularly limited as long as it is within the scope of the present invention, and the urethane resin can be prepared by known methods such as the following: A one-shot method in which a polyol component and a polyisocyanate component are mixed and reacted; A method in which an isocyanate-terminated prepolymer obtained by reacting a portion of a polyol with an isocyanate is reacted with a chain extender such as a low-molecular-weight polyol.

[0040] Examples of isocyanate components that can be used to prepare the urethane resin in the urethane resin particles of the present invention include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), phenylene diisocyanate (PPDI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), cyclohexane diisocyanate, and mixtures thereof. Copolymers, isocyanurates, TMP adducts, and biuret forms of these may also be used.

[0041] Examples of polyol components that can be used to prepare the urethane resin in the urethane resin particles of the present invention include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, acrylic polyols, and mixtures thereof. Among these, it is preferable to use a polyol component having the structure of formula (1) as described above. Specific examples include polycarbonate polyols of 3-methyl-1,5-propanediol (MPD), polyester polyols of MPD and sebacic acid, and polyester polyols of MPD and adipic acid.

[0042] Furthermore, examples of chain extenders that can be used in preparing the urethane resin in the urethane resin particles of the present invention include difunctional low-molecular-weight diols such as ethylene glycol and 1,4-butanediol, trifunctional low-molecular-weight triols such as trimethylolpropane, and mixtures thereof.

[0043] Alternatively, the above-mentioned various isocyanate compounds may be reacted in advance with various polyols in an excess state of isocyanate groups to prepare isocyanate-terminated prepolymers.These isocyanate compounds may also be materials in which the isocyanate groups have been blocked with various blocking agents such as MEK oxime.

[0044] The urethane resin contained in the urethane resin particles of the present invention is preferably a polymer of a composition containing a polyisocyanate having a nurate structure, a difunctional polyol, and a trifunctional or higher polyol.

[0045] By using a polyisocyanate having a nurate structure, the degree of crosslinking of the entire urethane resin particles can be increased, and the hardness and component fraction F of the urethane resin particles can be improved. ｓ This makes it easy to control A [%] within the above range.

[0046] As for the polyol component, it is preferable to use a bifunctional polyol and a trifunctional or higher polyol in combination.

[0047] By using a polyol having three or more functional groups in combination, the degree of crosslinking is further increased, making it easier to control the hardness within an appropriate range.

[0048] More preferably, the trifunctional or higher polyol is a tetrafunctional or higher polyol. By using a tetrafunctional or higher polyol, it is possible to locally form regions with a high degree of crosslinking within the molecular structure, i.e., hard segments. By locally arranging hard segments, even when the degree of crosslinking of the urethane resin particles is increased to suppress environmental dependency, the resin itself does not become too hard, making it easier to control the hardness of the urethane resin particles within the aforementioned range.

[0049] Among these, it is more preferable that the tetrafunctional or higher polyol is ethylenediamine modified with propylene oxide.

[0050] As mentioned above, a wide variety of commercially available polyols can be used as the bifunctional polyol, but among them, polycarbonate polyol is preferred for the purpose of improving the abrasion resistance of the urethane resin particles.

[0051] The molecular weight of the bifunctional polyol used is preferably 1,000 to 10,000. By having the molecular weight in this range, the distance between crosslinking points can be appropriately adjusted, and it is easy to prevent the urethane resin particles from becoming too hard or too soft. A molecular weight of 3,000 to 6,000 is more preferable.

[0052] The mixing ratio of the polyol component and the polyisocyanate component to be reacted is preferably such that the ratio of isocyanate groups to hydroxyl groups of the polyol is 1.0, in the range of 2.0 to 15.0.

[0053] It is more preferably 4.0 to 10.0, and even more preferably 5.0 to 7.5.

[0054] <Production Method> The method for producing the urethane resin particles of the present invention is not particularly limited, and any of the widely known methods for producing urethane resin particles can be used. Among these, production by a method of granulation in an aqueous medium, such as a suspension polymerization method or a dissolution suspension method, is preferred because it allows for easy control of the shape and particle size of the resulting urethane resin particles.

[0055] The suspension polymerization method, which is one of the preferred production methods, will be described below as an example.

[0056] <Preparation of Urethane Monomer Composition> In this step, the above-mentioned polyisocyanate, urethane resin monomers such as polyol, and other materials are mixed to prepare a urethane monomer composition. The mixing method is not particularly limited, and a uniformly dissolved and / or dispersed urethane monomer composition can be obtained using a commonly used stirrer, homogenizer, ultrasonic disperser, or the like.

[0057] It is also preferable to separately add a catalyst to the urethane monomer composition for the purpose of controlling the rate of urethane condensation and controlling the bond form. As the catalyst for urethane condensation, widely known catalysts can be used.

[0058] For example, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin thiocarboxylate, organotin compounds such as tin octenate; organolead compounds such as lead octenate; monoamines such as triethylamine and dimethylcyclohexylamine; diamines such as tetramethylethylenediamine, tetramethylpropanediamine, tetramethylhexanediamine; triamines such as pentamethyldiethylenetriamine, pentamethyldipropylenetriamine, tetramethylguanidine; cyclic amines such as triethylenediamine, dimethylpiperazine, methylethylpiperazine, methylmorpholine, dimethylaminoethylmorpholine, dimethylimidazole; alcohol amines such as dimethylaminoethanol, dimethylaminoethoxyethanol, trimethylaminoethylethanolamine, methylhydroxyethylpiperazine, hydroxyethylmorpholine; ether amines such as bis(dimethylaminoethyl)ether, ethylene glycol bis(dimethyl)aminopropyl ether, etc. These catalysts may be used alone or in combination of two or more. Among them, those generally called allophanation catalysts or nurate catalysts are preferred from the viewpoint of controlling the degree of crosslinking.

[0059] In addition, it is preferable to add an organic solvent to the urethane monomer composition for the purpose of adjusting the viscosity of the urethane monomer composition. The organic solvent is preferably one that can be uniformly mixed in the urethane monomer composition and does not inhibit the polymerization reaction.

[0060] For example, aromatic hydrocarbon solvents such as toluene, xylene, ethylbenzene, and tetralin; aliphatic or alicyclic hydrocarbon solvents such as n-hexane, n-heptane, mineral spirits, and cyclohexane; halogenated solvents such as methyl chloride, methyl bromide, methyl iodide, methylene dichloride, carbon tetrachloride, trichloroethylene, and perchloroethylene; ester or ester ether solvents such as ethyl acetate, butyl acetate, methoxybutyl acetate, methyl cellosolve acetate, and ethyl cellosolve acetate; diethyl ether, tetrahydrofuran, dioxane, ethyl cellosolve, butyl cellosolve, and proline. Examples of suitable solvents include ether-based solvents such as pyrene glycol monomethyl ether; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, di-n-butyl ketone, and cyclohexanone; alcohol-based solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, 2-ethylhexyl alcohol, and benzyl alcohol; amide-based solvents such as dimethylformamide and dimethylacetamide; sulfoxide-based solvents such as dimethyl sulfoxide; heterocyclic compound-based solvents such as N-methylpyrrolidone; and mixed solvents of two or more of these.

[0061] Increasing the amount of organic solvent added reduces the viscosity of the urethane monomer composition, which reduces the particle size of the dispersed droplets in the subsequent granulation step, and as a result, the average particle size of the resulting urethane resin particles tends to be smaller.

[0062] <Preparation of Aqueous Medium> In this step, an aqueous medium is prepared as a medium into which the urethane monomer composition is introduced and dispersed.

[0063] The aqueous medium may contain an inorganic or organic dispersion stabilizer.

[0064] As the dispersion stabilizer, known dispersion stabilizers can be used.

[0065] Examples of inorganic dispersion stabilizers include phosphates such as hydroxyapatite, tricalcium phosphate, dicalcium phosphate, magnesium phosphate, aluminum phosphate, and zinc phosphate; carbonates such as calcium carbonate and magnesium carbonate; metal hydroxides such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide; sulfates such as calcium sulfate and barium sulfate; calcium metasilicate; bentonite; silica; and alumina.

[0066] On the other hand, examples of organic dispersion stabilizers include polyvinyl alcohol, gelatin, methyl cellulose, methylhydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, polyacrylic acid and its salts, and starch.

[0067] When an inorganic compound is used as the dispersion stabilizer, a commercially available product may be used as is, but in order to obtain finer particles, the inorganic compound may be formed in an aqueous medium and then used.

[0068] For example, in the case of calcium phosphates such as hydroxyapatite and tricalcium phosphate, an aqueous solution of the phosphate salt and an aqueous solution of the calcium salt may be mixed under high agitation.

[0069] The aqueous medium may contain a surfactant. Known surfactants can be used as the surfactant. Examples of such surfactants include anionic surfactants such as sodium dodecylbenzene sulfate and sodium oleate; cationic surfactants; amphoteric surfactants; and nonionic surfactants.

[0070] The particle size of the resulting urethane resin particles can be controlled by controlling the amount of dispersant added. Increasing the amount of dispersant added tends to reduce the particle size of the dispersed droplets in the subsequent granulation step, resulting in a smaller average particle size of the resulting urethane resin particles.

[0071] <Granulation Step> In this step, the aqueous medium and the urethane monomer composition are supplied to a granulation device at a fixed ratio to prepare a granulation liquid in which droplets of the urethane monomer composition are dispersed in the aqueous medium. The method for supplying the aqueous dispersion medium and the urethane monomer composition is not particularly limited; they may be supplied separately. Alternatively, a premix of the aqueous dispersion medium and the urethane monomer composition may be supplied. The particle size of the urethane monomer composition droplets can be controlled by appropriately adjusting the shear force applied to the granulation liquid. The shear force can be controlled by the type of disperser used and operating conditions such as the rotation speed. Increasing the shear force applied to the granulation liquid tends to reduce the particle size of the dispersion droplets in the subsequent granulation step, resulting in a smaller average particle size of the resulting urethane resin particles.

[0072] The granulation process may be a batch process or a circulation process, and can be appropriately selected.

[0073] <Condensation / solvent removal step> In this step, the granulation liquid is heated to promote condensation of the urethane monomer composition, thereby preparing a dispersion in which urethane resin particles are dispersed. A general temperature-controllable stirring tank can be used for the condensation step in the present invention. The condensation temperature may be constant throughout, but may be increased in the latter half of the polymerization step in order to obtain the desired molecular weight distribution.

[0074] Furthermore, after the completion of the condensation, a part of the aqueous medium may be distilled off to remove impurities such as unreacted monomers and solvents. The distillation can be carried out under atmospheric pressure or reduced pressure.

[0075] (Separation and Purification Step) In this step, the urethane resin particles are separated and purified from a dispersion in which the urethane resin particles are dispersed to prepare the urethane resin particles of the present invention. The urethane resin particles are separated from the liquid phase by a general solid-liquid separation method. At this time, the urethane resin particle dispersion may be treated with an acid, alkali, or other treating agent in order to remove the dispersion stabilizer adhering to the surface of the urethane resin particles.

[0076] The resulting urethane resin particles are dried by a known drying means, if necessary.

[0077] The urethane resin particles of the present invention preferably have a volume average particle size of 5.0 μm or more and 50.0 μm or less, and more preferably 10.0 μm or more and 50.0 μm or less. A volume average particle size within this range makes them easy to handle as a powder and disperse, making it easier to uniformly impart functionality to products.

[0078] In order to control the volume average particle size within the above range, an additional operation may be performed, such as classifying the particles with an air classifier to remove particles that fall outside the desired particle size distribution as non-predetermined particles.

[0079] <Measurement Method> Next, the measurement method for each physical property according to the present disclosure will be described.

[0080] (Stress when the urethane resin particles are compressed by 10% of their particle size) The stress when the urethane resin particles are compressed by 10% of their particle size can be calculated from the load-deformation ratio curve obtained by an indentation test. Specifically, a microparticle crushing force measuring device "NS-A100" (manufactured by Nano Seeds Co., Ltd.) is used. The specific method for measuring the load-deformation ratio curve is as follows.

[0081] The measurement was carried out in a laboratory environment of 23°C and 50% RH, and the sample stage was kept at 23.0°C using an attached temperature control device.

[0082] After applying urethane resin particles to the sample stage, the sample stage is set to the aforementioned temperature and maintained for 10 minutes or more before measurement.

[0083] The measurement is carried out using a flat indenter with a force of 0.072 mN / μm attached to the device.

[0084] The indentation amount of the test is set to 40 μm, the indenter moving speed is set to 0.5 μm / s, and the number of indentation data is set to 3001.

[0085] The particles to be measured are selected to be urethane resin particles present alone on the measurement screen of the microscope attached to the device. However, to minimize errors in the amount of displacement, particles with a particle diameter (D) within ±0.5 μm of the volume average particle diameter (Dv) (Dv - 0.5 μm ≦ D ≦ Dv + 0.5 μm) are selected. The software attached to the device is used to measure the major and minor axes of the urethane resin particles, and the particle diameter D (μm) of the particles to be measured is calculated as [(major axis + minor axis) / 2]. The volume average particle diameter (Dv) is measured using a "CDA-1000X" (manufactured by Sysmex Corporation) using the method described below.

[0086] For the measurement, 100 urethane resin particles having a particle diameter D (μm) that satisfies the above condition are selected and measured.

[0087] The analysis is performed using the "A100 Strain Analysis Graph Creation Tool" that comes with the "NS-A100" microparticle crushing force measuring device. When the "Graph Creation" menu is selected and measurement data is selected, the load and deformation amount are output as analysis data. The deformation rate can be derived by dividing the obtained deformation amount by the particle diameter D (μm) before measurement, and a load-deformation rate curve can be obtained. On the obtained load-deformation rate curve, the load at the point where the deformation rate is 10% is read.

[0088] The above measurements and analyses were carried out on 100 urethane resin particles, and the arithmetic mean value was calculated as the stress when the urethane resin particles were compressed by 10% of their particle size in the present invention.

[0089] Similar measurements were carried out with the sample stage temperature controlled at 10.0° C. and 40.0° C., and the stress when the urethane resin particles were compressed by 10% of their particle size at each temperature was calculated.

[0090] (Glass Transition Temperature of the Urethane Resin Particles) The glass transition temperature (Tg) is measured in accordance with ASTM D3418-82 using a differential scanning calorimeter "Q2000" (manufactured by TA Instruments). The melting points of indium and zinc are used to correct the temperature of the detector, and the heat of fusion of indium is used to correct the heat quantity.

[0091] Specifically, approximately 3 mg of urethane resin powder is weighed out and placed in an aluminum pan. An empty aluminum pan is used as a reference, and measurements are made at a temperature rise rate of 10°C / min within a measurement temperature range of -80°C to 200°C. During the measurement, the temperature is first raised to 200°C, then lowered to -80°C, and then raised again. The intersection of the line midway between the baselines before and after the specific heat change that appears during this second temperature rise and the differential thermal curve is taken as the glass transition temperature of the urethane resin particles.

[0092] (F of the urethane resin particles ｓ A, F ｓ B, F ｓ Measurement of F of urethane resin particles ｓ A is a hydrogen nucleus as follows: １ The values ​​were calculated from the results of pulsed NMR measurements using H as the measurement nucleus.

[0093] 1 g of urethane resin powder was placed in a sample tube and subjected to pulse NMR measurement using the following equipment and conditions: Equipment: minispec mq20 (manufactured by Bruker) Measurement mode: Solid-Echo Scan: 64 Recycle Delay: 1 sec 90° Pulse Length: 2.78 μsec 180° Pulse Length: 5.46 μsec Acquisition scale: 1.5 to 4 msec (adjusted appropriately based on the measured relaxation curve) Measurement temperature: 23°C

[0094] The obtained echo intensity curve was subjected to three-component automatic fitting using standard software, TDNMR-A, and the component with the shortest relaxation time among the three components was designated as component T ２ｓ A is the component T in the urethane resin particles. ２ｓ The component fraction of A is F ｓ A [%].

[0095] If it is not possible to separate the three components, separate the two components, and similarly, separate the component with the shorter relaxation time into component T ２ｓ A, component fraction F ｓ A [%] was calculated.

[0096] Similarly, the echo intensity curve measured at a measurement temperature of 10°C is subjected to three-component automatic fitting using standard software TDNMR-A. Then, the component with the shortest relaxation time among the three components is designated as component T ２ｓ B, and the component T in the urethane resin particles ２ｓ The component fraction of B is F ｓ B [%].

[0097] Furthermore, the echo intensity curve measured at a measurement temperature of 40°C is subjected to three-component automatic fitting using standard software TDNMR-A. Then, the component with the shortest relaxation time among the three components is designated as component T ２ｓ C, and the component T in the urethane resin particles ２ｓ The component fraction of C is F ｓ C [%].

[0098] (Measurement of volume average particle diameter of the urethane resin powder) The volume average particle diameter (Dv) of the urethane resin particles is calculated as follows. As the measuring device, a particle counting analyzer "CDA-1000X" (manufactured by Sysmex Corporation) using a capillary electrical resistance method and equipped with a 100 μm aperture tube is used. The measurement conditions are set and the measurement data is analyzed using the accompanying dedicated software "CDA-1000X" (manufactured by Sysmex Corporation).

[0099] The aqueous electrolyte solution used for the measurement may be, for example, "Cell Pack" (manufactured by Sysmex Corporation).

[0100] Before carrying out the measurements and analysis, the dedicated software was set up as follows.

[0101] On the "measurement condition setting" screen of the dedicated software, set the total count number to 50,000, the number of repeated measurements to 1, and the measurement mode to total count (no limit).

[0102] The specific measurement method is as follows: (1) Approximately 150 ml of the electrolyte solution is placed in a dedicated glass round-bottom beaker, which is then placed on the sample stage. The stirring propeller is set to 500 rpm. Then, click "Blank Check Measurement" in the dedicated software to begin the measurement and confirm that the count is less than 500. If the count is 500 or more, repeatedly clean the beaker and aperture. (2) Approximately 30 ml of the electrolyte solution is placed in a 100 ml flat-bottom glass beaker. Approximately 0.3 ml of a solution prepared by diluting "Contaminon N" (a 10% by weight aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) approximately three times by weight with ion-exchanged water is added to the beaker. (3) An ultrasonic disperser "Ultrasonic Dispersion System Tetra 150" (manufactured by Nikkaki Bios Co., Ltd.) with an electrical output of 120 W and two built-in oscillators with an oscillation frequency of 50 kHz and a phase difference of 180 degrees was prepared. Approximately 3.3 L of ion-exchanged water was placed in the ultrasonic disperser's water tank, and approximately 2 mL of Contaminon N was added to the water tank. (4) The beaker from (2) was placed in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser was operated. The height of the beaker was then adjusted so that the resonance state of the electrolyte solution in the beaker was maximized. (5) While ultrasonic waves were irradiated to the electrolyte solution in the beaker from (4), approximately 10 mg of urethane resin particles were added in small amounts and dispersed. The ultrasonic dispersion process was then continued for another 60 seconds. During ultrasonic dispersion, the water temperature in the water tank was appropriately adjusted to be between 10°C and 40°C. (6) Using a pipette, the electrolyte aqueous solution (5) containing dispersed urethane resin particles is dropped into the round-bottom beaker (1) placed in the sample stand, and the measurement concentration is adjusted to approximately 6%. Measurements are then continued until the number of particles measured reaches 50,000. (7) The measurement data is analyzed using dedicated software provided with the device, and the volume average particle size (Dv) is calculated.

[0103] (Measurement of Average Circularity of Urethane Resin Powder) The average circularity of the urethane resin powder is measured using a flow particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) under the measurement and analysis conditions during calibration.

[0104] The specific measurement method is as follows. First, approximately 20 ml of ion-exchanged water, from which impurities such as solids have been removed, is placed in a glass container. Approximately 0.2 ml of a dilution prepared by diluting "Contaminon N" (a 10% by weight aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) approximately three times by weight with ion-exchanged water is added to the container. Approximately 0.02 g of the measurement sample is then added, and the mixture is dispersed for two minutes using an ultrasonic disperser to obtain a dispersion for measurement. The dispersion is then appropriately cooled so that its temperature is between 10°C and 40°C. A tabletop ultrasonic cleaner disperser with an oscillation frequency of 50 kHz and an electrical output of 150 W (e.g., "VS-150" manufactured by Vervoclear) is used as the ultrasonic disperser. A predetermined amount of ion-exchanged water is placed in the water tank, and approximately 2 ml of the Contaminon N is added to the water tank.

[0105] For the measurements, the flow particle image analyzer described above equipped with an "UPlanApro" objective lens (magnification 10x, numerical aperture 0.40) was used, and a particle sheath "PSE-900A" (manufactured by Sysmex Corporation) was used as the sheath liquid. The dispersion prepared according to the above procedure was introduced into the flow particle image analyzer, and 3,000 urethane resin particles were measured in HPF measurement mode and total count mode. The binarization threshold for particle analysis was set to 85%, and the analyzed particle diameters were limited to a circle-equivalent diameter of 1.985 μm or more and less than 39.69 μm, and the average circularity of the urethane resin particles was determined.

[0106] Before starting the measurement, automatic focus adjustment is performed using standard latex particles (for example, "RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5200A" manufactured by Duke Scientific diluted with ion-exchanged water). Thereafter, it is preferable to perform focus adjustment every two hours from the start of the measurement.

[0107] If the volume average particle size exceeds 40 μm and the average circularity cannot be calculated by the above method, the urethane resin powder is observed with a scanning electron microscope, and the projected area S, perimeter L, etc. of the urethane resin particles are measured from the observed image using the image processing software "ImageJ."

[0108] The circularity of each urethane resin particle was calculated from the obtained area S and perimeter L using the following formula: Circularity C = 2 × (π × S) １／２ / L

[0109] The same procedure is carried out for 100 urethane resin particles, and the average value is taken as the average circularity.

[0110] (Molecular Structure Analysis of the Urethane Resin) The molecular structure of the urethane resin in the urethane resin particles was analyzed by pyrolysis GC / MS, ATR-IR, １ H-NMR, １３ This is done by C-NMR. If the structure cannot be identified by each analysis alone, structural analysis is performed by combining multiple analyses. Representative measurement methods are shown below.

[0111] [Pyrolysis GC / MS] ・Pyrolysis device: JPS-700 (Nippon Analytical Industry) ・Decomposition temperature: 590°C ・GC / MS device: Focus GC / ISQ (Thermo Fisher) ・Column: HP-5MS Length 60m, inner diameter 0.25mm, film thickness 0.25μm ・Inlet temperature: 200°C・Flow pressure: 100kPa ・Split: 50mL / min ・MS ionization: EI ・Ion source temperature: 200℃ Mass Range 45-650

[0112] The types of constituent compounds are identified by analyzing the mass spectrum of the components of the resin decomposition products that are produced when the resin is thermally decomposed under the above conditions.

[0113] [ATR-IR] A Fourier transform infrared spectrometer (Spectrum One, manufactured by PerkinElmer) equipped with a universal ATR measurement accessory (Universal ATR Sampling Accessory) was used to perform measurements and structural analysis under the following conditions: Infrared light (λ = 5 μm) incident angle: 45° ATR crystal: Ge ATR crystal (refractive index = 4.0) Range Start: 4000 cm －１ End: 650cm －１ (Ge ATR crystal) Duration Scan number: 16 Resolution: 4.00 cm －１ Advanced: CO2 / H2O correction

[0114] [ １ H-NMR] Measurement equipment: FT NMR equipment JNM-EX400 (manufactured by JEOL Ltd.) Measurement frequency: 400 MHz Pulse condition: 5.0 μs Frequency range: 10,500 Hz Number of accumulations: 64 Measurement temperature: 30°C Sample: 50 mg of the urethane resin powder was placed in a sample tube with an inner diameter of 5 mm, and deuterated chloroform (CDCl) was used as a solvent. ３ ) is added and dissolved in a thermostatic bath at 40°C to prepare the solution.

[0115] obtained １ The H-NMR chart is analyzed to perform structural analysis of the urethane resin.

[0116] Similarly, the measured nuclei are １３ C, and the measurement was performed in single pulse mode. １３ The structure of the urethane resin may be analyzed by analyzing a C-NMR chart.

[0117] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples without departing from the gist of the present invention. In the following description of the examples, "parts" are by mass unless otherwise specified.

[0118] <<Preparation of Urethane Resin Powder 1>> <Preparation of Aqueous Medium 1> A dispersant, Metolose 65SH-50 (a cellulose derivative manufactured by Shin-Etsu Chemical Co., Ltd.), was dissolved in ion-exchanged water to a concentration of 4.0 mass % to obtain aqueous medium 1.

[0119] <Preparation of Urethane Monomer Composition 1> The following materials were placed in a plastic container compatible with a planetary centrifugal mixer (ARV-310P manufactured by THINKY Corporation): Kuraray Polyol C-3090 (poly[(3-methyl-1,5-pentanediol:1,6-hexanediol) carbonate] polycarbonate polyol manufactured by Kuraray Co., Ltd., molecular weight 3000, OHV=20): 54.1 parts by mass; Sannix NP-300 (propylene oxide-modified ethylenediamine manufactured by Sanyo Chemical Industries, Ltd., OHV=151): 2.9 parts by mass; and methyl ethyl ketone (MEK): 33.3 parts by mass.

[0120] The mixture was mixed using a planetary centrifugal mixer at 2000 rpm for 60 seconds.

[0121] Next, the following materials were quickly weighed into the same container: Duranate TKA100 (a polyisocyanate (nurate) of hexamethylene diisocyanate, manufactured by Asahi Kasei Corporation, NCO%=21.8): 43.0 parts by mass; TOYO-CAT RX-5 (a tertiary amine catalyst, manufactured by Tosoh Corporation): 2000 ppm (based on the total amount of isocyanate and polyol).

[0122] Again, the mixture was mixed using the planetary centrifugal mixer at 2000 rpm and 0.2 kPa for 90 seconds to obtain urethane monomer composition 1.

[0123] Since the reaction of urethane monomer composition 1 proceeds even at room temperature, the preparation was carried out so as to shorten the time until the start of the next granulation step as much as possible.

[0124] <Granulation Step> 266.7 parts by mass of aqueous medium 1 was weighed into a reaction vessel equipped with a stirrer, and the temperature was adjusted to 30°C.

[0125] While the reaction vessel was continuously stirred at 1000 rpm with a stirrer, 133.3 parts by mass of the urethane monomer composition was added, and stirring was continued for 60 minutes, thereby obtaining granulation liquid 1.

[0126] <Condensation / solvent removal step> After the granulation step was completed, the vessel containing the granulation liquid 1 was heated to 70°C while stirring at 200 rpm, and a condensation step was carried out for 5 hours. The vessel was further heated to 100°C while stirring at 200 rpm, and a solvent removal step was carried out for 5 hours, to obtain dispersion liquid 1.

[0127] <Separation and purification step> After the solvent removal step was completed, the solid content was filtered out from the dispersion liquid 1, thoroughly washed with ion-exchanged water, and then vacuum dried at 30°C for 24 hours to obtain a urethane resin powder 1 containing urethane resin particles.

[0128] The physical properties and compositional analysis results of the obtained urethane resin powder 1 are shown in Table 3.

[0129] <<Preparation of Urethane Resin Powders 2 to 10>> Urethane resin powders 2 to 10 were obtained in the same manner as in the production method of urethane resin powder 1, except that the various materials and production conditions were changed as shown in Tables 1 and 2. The physical properties and composition analysis results of the obtained urethane resin powders 2 to 10 are shown in Table 3.

[0130]

[0131] The symbols in Table 1 represent the following: TPA100: Duranate TPA100 (manufactured by Asahi Kasei Corporation, polyisocyanate (nurate) of hexamethylene diisocyanate, NCO%=23.1) TMA100: Duranate TMA100 (manufactured by Asahi Kasei Corporation, polyisocyanate (nurate) of hexamethylene diisocyanate, NCO%=23.2) C-1090: Kuraray Polyol C-1090 (poly[(3-methyl-1,5-pentanediol:1,6-hexanediol) carbonate], Kuraray Co., Ltd., polycarbonate polyol, molecular weight 1000, OHV=112.0) P-6010: Kuraray Polyol P-6010 (poly((3-methyl-1,5-pentanediol)-alt-(adipic acid)) Polyester polyol (molecular weight 6000, OHV = 19.7) manufactured by Kuraray Co., Ltd. TMP: Trimethylolpropane

[0132]

[0133] The symbols in Table 2 represent the following: 90SH-100: Metrose 90SH-100 (cellulose derivative manufactured by Shin-Etsu Chemical Co., Ltd.)

[0134] <Urethane Resin Powder 11> Art Pearl C300T manufactured by Negami Chemical Industrial Co., Ltd. was used as the urethane resin particles 11.

[0135] The physical properties of the urethane resin powder 11 are shown in Table 3.

[0136] <Urethane Resin Powder 12> Art Pearl U600T manufactured by Negami Chemical Industrial Co., Ltd. was used as the urethane resin particles 12.

[0137] The physical properties of the urethane resin powder 12 are shown in Table 3.

[0138] <Urethane Resin Powder 13> Art Pearl CE400T manufactured by Negami Chemical Industrial Co., Ltd. was used as urethane resin particles 13.

[0139] The physical properties of the urethane resin powder 13 are shown in Table 3.

[0140] <Urethane resin powder 14> The following materials were weighed into a 1000 mL jacketed four-neck separable flask: 17.5 g of thermoplastic polyurethane elastomer ("Elastollan" 1180A10, manufactured by BASF Japan Ltd., weight average molecular weight 130,000, soft segment component amount 88%); 35.0 g of polyvinyl alcohol ("GOHSENOL" GL-05, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., weight average molecular weight 11,000); and 297.5 g of N-methyl-2-pyrrolidone as an organic solvent.

[0141] The separable flask was heated to 80 ° C. and stirred at 450 rpm for 2 hours with a helical ribbon-type stirring blade to form an emulsion. Then, 350 g of ion-exchanged water as a poor solvent was added dropwise via a liquid pump at a speed of 2.91 g / min. After the entire amount of ion-exchanged water was added, the temperature was lowered while stirring to obtain a white dispersion 20. The obtained dispersion 20 was centrifuged at 7500 G for 15 minutes to separate the solid and liquid. 250 g of ion-exchanged water was then added and the mixture was reslurried at 80 ° C. for 30 minutes. Subsequently, vacuum filtration was performed, and the reslurry washing and vacuum filtration were repeated again. 300 g of ion-exchanged water was added to obtain a slurry 14. The obtained slurry 14 was freeze-dried to obtain a urethane resin powder 14.

[0142] The physical properties of the obtained urethane resin powder 14 are shown in Table 3.

[0143]

[0144] The symbols in Table 3 represent the following: PC: Polycarbonate backbone PES: Polyester backbone

[0145] Furthermore, items marked with a circle represent items for which the corresponding structure was detected as a result of composition analysis, items marked with a - represent items for which the corresponding structure was not detected as a result of composition analysis, and items marked with a diagonal line represent items for which neither physical property measurement nor composition analysis was performed.

[0146] <Examples 1 to 8 and Comparative Examples 1 to 6> Evaluation samples were prepared using the obtained urethane resin powders 1 to 14 as follows, and evaluated from the viewpoints of environmental dependency and abrasion resistance. These were designated as Examples 1 to 8 and Comparative Examples 1 to 6.

[0147] The evaluation results are shown in Table 4.

[0148] (Preparation of Paint) Urethane resin 100 parts by mass (Crisbon NY-373, manufactured by Dainippon Ink and Chemicals, Inc.) Each urethane resin powder 100 parts by mass High molecular weight silicone oil 2 parts by mass (silicone oil, KP340, manufactured by Shin-Etsu Silicones Co., Ltd.) Fine particle silica 12 parts by mass (Nipsil E220, manufactured by Nippon Silica Industry Co., Ltd., average particle size: 1.5 μm) Solvent 1000 parts by mass (IPA / DMF / ethyl acetate mixture)

[0149] The above materials were thoroughly mixed to prepare a paint.

[0150] (Preparation of Evaluation Sample) An olefin-based thermoplastic elastomer (a mixture of PP / PE / EPDM blended at a mixing ratio of 36 / 28 / 36) was molded into a sheet having a thickness of 800 μm to serve as a substrate. The above coating material was applied to the surface of the substrate in a dry mass of 20 g / m. ２ After coating in the amount of coating, the coating was dried in a hot air drying oven at 100° C. for 3 minutes to prepare an evaluation sample.

[0151] <Tactile Evaluation> The obtained evaluation samples were left for 24 hours in an environment of 15°C and 10% RH, an environment of 23°C and 50% RH, and an environment of 30°C and 80% RH, and then the tactile feel was evaluated to evaluate environmental dependency. A: The difference in hardness between 10°C and 40°C was 0.20 or less, and there was almost no difference in the tactile feel depending on the environment. B: The difference in hardness between 10°C and 40°C was more than 0.20 and less than 0.24, and there was a slight difference in the tactile feel depending on the environment. C: The difference in hardness between 10°C and 40°C was 0.25 or more and less than 0.30, and there was a difference in the tactile feel depending on the environment. D: The difference in hardness between 10°C and 40°C was 0.30 or more, and there was a significant difference in the tactile feel depending on the environment.

[0152] <Stress when compressed 10% in an environment of 23°C and 50% RH> The stress measured when compressed 10% in an environment of 23°C and 50% RH was evaluated according to the following evaluation criteria: A: 0.26 mN or more and 0.38 mN or less B: 0.25 mN or more and less than 0.26 mN, or more than 0.38 mN and 0.50 mN or less C: Less than 0.25 mN, or more than 0.50 mN

[0153] <Friction Resistance> Five layers of gauze (Japanese Pharmacopoeia) were placed in close contact with the obtained evaluation sample under a constant load, and the sample was rubbed back and forth a specified number of times with a stroke of 100 mm. The state of the particles after rubbing was observed using an SEM, and the degree of particle deterioration was evaluated according to the following criteria. A: The particle size and aspect ratio changed by less than 3.0%. B: The particle size and aspect ratio changed by 3.0% or more but less than 5.0%. C: The particle size and aspect ratio changed by 5.0% or more.

[0154]

[0155] The present disclosure relates to the following configurations.

[0156] (Configuration 1) A urethane resin powder containing urethane resin particles, wherein the urethane resin particles contain a urethane resin; the urethane resin particles contained in the urethane resin powder have an average circularity of 0.950 or more; the stress when the urethane resin particles are compressed by 10% of their particle size in an environment of 23°C and 50% RH is 0.25 mN or more and 0.50 mN or less; and the glass transition temperature of the urethane resin particles is 0°C or less.

[0157] (Configuration 2) In pulse NMR measurement of the urethane resin particles at a measurement temperature of 23°C, hydrogen nuclei １ The spin-spin relaxation time T with H as the measurement nucleus ２ Measurement is performed by a solid echo method to obtain an echo intensity curve A of the urethane resin particles, and the echo intensity curve A is decomposed into three components by the least squares method. The component with the shortest relaxation time among the three components is designated as component T. ２ｓ A is the component T in the urethane resin particles. ２ｓ The component fraction of A is F ｓ When A [%], the component fraction F ｓ 2. The urethane resin powder according to claim 1, wherein A is 15 or more and 90 or less.

[0158] (Configuration 3) In pulse NMR measurement of the urethane resin particles at a measurement temperature of 10°C, hydrogen nuclei １ The spin-spin relaxation time T with H as the measurement nucleus ２ Measurement is performed by a solid echo method to obtain an echo intensity curve B of the urethane resin particles, and the echo intensity curve B is decomposed into three components by the least squares method. The component with the shortest relaxation time among the three components is designated as component T. ２ｓ B, and the component T in the urethane resin particles ２ｓ The component fraction of B is F ｓB [%], and in pulse NMR measurement of the urethane resin particles at a measurement temperature of 40°C, １ The spin-spin relaxation time T with H as the measurement nucleus ２ Measurement is performed by a solid echo method to obtain an echo intensity curve C of the urethane resin particles, and the echo intensity curve C is decomposed into three components by the least squares method. The component with the shortest relaxation time among the three components is designated as component T. ２ｓ C, and the component T in the urethane resin particles ２ｓ The component fraction of C is F ｓ When C [%] is used, F ｓ B / F ｓ 3. The urethane resin powder according to claim 1, wherein C is 1.0 or more and 1.5 or less.

[0159] (Configuration 4) The urethane resin powder according to any one of Configurations 1 to 3, wherein the urethane resin particles have a volume average particle size of 10.0 μm or more and 50.0 μm or less.

[0160] (Configuration 5) The urethane resin powder according to any one of Configurations 1 to 4, wherein the urethane resin particles have an average circularity of 0.950 or more.

[0161] (Configuration 6) The urethane resin has a partial structure represented by the following formula (1):

[0162]

[0163] 6. The urethane resin powder according to any one of configurations 1 to 5, having:

[0164] (Configuration 7) The urethane resin particles according to any one of Configurations 1 to 6, wherein the urethane resin is a polymer of a composition containing a polyisocyanate having a nurate structure, a bifunctional polyol, and a trifunctional or higher polyol.

[0165] (Configuration 8) The urethane resin particles according to Configuration 7, wherein the bifunctional polyol is a polycarbonate polyol.

[0166] (Configuration 9) The urethane resin particles according to Configuration 7 or 8, wherein the tri- or higher functional polyol is a tetra- or higher functional polyol.

[0167] (Configuration 10) The urethane resin particles according to Configuration 9, wherein the tetrafunctional or higher polyol is ethylenediamine modified with propylene oxide.

[0168] (Configuration 11) The urethane resin powder according to any one of Configurations 1 to 10, wherein the stress when the urethane resin particles are compressed by 10% of their particle size in an environment of 23°C and 50% RH is 0.26 mN or more and 0.38 mN or less.

[0169] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0170] This application claims priority based on Japanese Patent Application No. 2024-069696 filed on April 23, 2024 and Japanese Patent Application No. 2024-158662 filed on September 12, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A urethane resin powder containing urethane resin particles, characterized in that the urethane resin particles contain a urethane resin, and when compressed by 10% of their particle size in an environment of 23°C and 50% RH, the stress is 0.25 mN or more and 0.50 mN or less, and the glass transition temperature of the urethane resin particles is 0°C or less.

2. In pulse NMR measurement of the urethane resin particles at a measurement temperature of 23°C, hydrogen nuclei １ The spin-spin relaxation time T with H as the measurement nucleus ２ Measurement is performed by a solid echo method to obtain an echo intensity curve A of the urethane resin particles, and the echo intensity curve A is decomposed into three components by the least squares method. The component with the shortest relaxation time among the three components is designated as component T. ２ｓ A is the component T in the urethane resin particles. ２ｓ The component fraction of A is F ｓ When A [%], the component fraction F ｓ 2. The urethane resin powder according to claim 1, wherein A is 15 or more and 90 or less.

3. In pulse NMR measurement of the urethane resin particles at a measurement temperature of 10°C, hydrogen nuclei １ The spin-spin relaxation time T with H as the measurement nucleus ２ Measurement is performed by a solid echo method to obtain an echo intensity curve B of the urethane resin particles, and the echo intensity curve B is decomposed into three components by the least squares method. The component with the shortest relaxation time among the three components is designated as component T. ２ｓ B, and the component T in the urethane resin particles ２ｓ The component fraction of B is F ｓ B [%], and in pulse NMR measurement of the urethane resin particles at a measurement temperature of 40°C, １ The spin-spin relaxation time T with H as the measurement nucleus ２ Measurement is performed by a solid echo method to obtain an echo intensity curve C of the urethane resin particles, and the echo intensity curve C is decomposed into three components by the least squares method. The component with the shortest relaxation time among the three components is designated as component T. ２ｓ C, and the component T in the urethane resin particles ２ｓ The component fraction of C is F ｓ When C [%] is used, F ｓ B / F ｓ 2. The urethane resin powder according to claim 1, wherein C is 1.0 or more and 1.5 or less.

4. The urethane resin powder according to any one of claims 1 to 3, wherein the volume average particle size of the urethane resin particles is 10.0 μm or more and 50.0 μm or less.

5. The urethane resin powder according to any one of claims 1 to 3, wherein the urethane resin particles have an average circularity of 0.950 or more.

6. The urethane resin has a partial structure represented by the following formula (1): The urethane resin powder according to any one of claims 1 to 3, having 7. The urethane resin particles according to claim 1, wherein the urethane resin is a polymer of a composition containing a polyisocyanate having a nurate structure, a difunctional polyol, and a trifunctional or higher polyol.

8. The urethane resin particles according to claim 7, wherein the bifunctional polyol is a polycarbonate polyol.

9. The urethane resin particles according to claim 7 or 8, wherein the tri- or higher functional polyol is a tetra- or higher functional polyol.

10. The urethane resin particles according to claim 9, wherein the polyol having four or more functional groups is ethylenediamine modified with propylene oxide.

11. The urethane resin powder according to claim 1, wherein the stress when the urethane resin particles are compressed by 10% of their particle size in an environment of 23°C and 50% RH is 0.26 mN or more and 0.38 mN or less.

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