Urethane resin powder

Abstract

To provide a urethane resin powder containing urethane resin particles having moderate hardness and low environmental dependency.SOLUTION: A urethane resin powder contains urethane resin particles containing a urethane resin. An average circularity of the urethane resin particles contained in the urethane resin powder is 0.950 or more, a 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 mN to 0.50 mN, and a glass transition temperature of the urethane resin particles is 0°C or lower.SELECTED DRAWING: None

Description

[Technical Field]

[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. [Background technology]

[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 perspective of the feel and flexibility of products that use 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. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-4142 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-35249 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the important functions required of urethane particles is that their performance does not change much depending on the season or the environment in which they are used, i.e., their hardness has little dependency on the environment. However, to date, no urethane resin particles have been found that have both an appropriate hardness and a low dependency on the environment. That is, an object of the present invention is to provide a urethane resin powder containing urethane resin particles that have an appropriate hardness and a low dependency on the environment. [Means for solving the problem]

[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. [Effects of the Invention]

[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. DETAILED DESCRIPTION OF THE INVENTION

[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 discovered 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 to 10% of their particle size in a 23°C, 50% RH environment, and by controlling the glass transition temperature to 0°C or less.

[0009] The present disclosure provides a urethane resin powder containing urethane resin particles containing 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 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; The urethane resin powder is characterized in that the glass transition temperature of the urethane resin particles is 0°C or lower.

[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, in the temperature range where they exist in a glassy or rubbery state without a state transition, they are characterized by little change in hardness with temperature. 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 change little in hardness with temperature. That is, they are little dependent on the environment.

[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 perimeter of the circle calculated from the equivalent circle diameter divided by the perimeter of the projected particle image, and is calculated using the following formula: Circularity C=2×(π×S) 1 / 2 / L

[0015] After calculating the circularity of each particle, the range of circularity of 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 defined 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, the variation in performance due to the particle shape can be suppressed. The average circularity can be controlled by changing the type of monomer used or the manufacturing 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 to 10% of their particle size in a 23°C, 50% RH environment. 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 imparted 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 other factors.

[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 chemical 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., the hydrogen nuclei 1 The spin-spin relaxation time T2 measurement using H as the measurement nucleus is performed by the solid echo method, and the echo intensity curve A of the urethane resin powder is obtained. 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] Said 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 where part of the molecular chain is oriented and stacked are included in component T.2s It is detected as A.

[0025] Ingredient T 2s component fraction F of A s By controlling A [%] within the above range, it is possible to obtain urethane resin particles that are less dependent on the environment. 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 manufacturing 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 multifunctional monomer component. s A[%] can be increased.

[0027] The urethane resin particles of the present invention are (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 T2 was measured using the solid echo method with H as the measurement nucleus. The echo intensity curve B of the urethane resin powder is obtained, 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 powder 2s The component fraction of B is F s B [%], (2) In pulse NMR measurement of the urethane resin powder at a measurement temperature of 40°C, hydrogen nuclei 1 The spin-spin relaxation time T2 was measured using the solid echo method with H as the measurement nucleus. The echo intensity curve C of the urethane resin powder is obtained, 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 Let C, The component T in the urethane resin powder2s The component fraction of C is F s When C[%] is used, F s B / F s It is preferable that C is 1.0 or more and 1.5 or less.

[0028] Said 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 component fraction F of C s B, and F s Let C. Then, F s F against C s B ratio 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 small value of C means that the component T detected as a hard segment 2s B, and component T 2s It 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. As mentioned above, it is preferable to add a polyfunctional monomer to increase the amount of 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 component is contained in an amount of 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] [ka]

[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 easy 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 falls within the scope of the present invention, and the urethane resin can be prepared by any of the following known methods. One-shot method in which polyol and polyisocyanate components are mixed and reacted A method in which an isocyanate-terminated prepolymer obtained by reacting a part 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 biurets 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 polyisocyanate with a nurate structure, the degree of cross-linking 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 It becomes 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 with three or more functionalities 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. Use of a tetrafunctional or higher polyol allows for the local formation of highly crosslinked regions, i.e., hard segments, within the molecular structure. By locally disposing the hard segments, even when the crosslinking degree of the urethane resin particles is increased to reduce 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 these, polycarbonate polyols are 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, making it easier 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, within 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] <Manufacturing 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 urethane resin monomers, such as the polyisocyanate and 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, organic tin compounds such as dibutyltin dilaurate, dibutyltin diacetate, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin thiocarboxylate, and tin octenoate; organic lead compounds such as lead octenoate; monoamines such as triethylamine and dimethylcyclohexylamine; diamines such as tetramethylethylenediamine, tetramethylpropanediamine, and tetramethylhexanediamine; triamines such as pentamethyldiethylenetriamine, pentamethyldipropylenetriamine, and tetramethylguanidine; cyclic amines such as triethylenediamine, dimethylpiperazine, methylethylpiperazine, methylmorpholine, dimethylaminoethylmorpholine, and dimethylimidazole; alcohol amines such as dimethylaminoethanol, dimethylaminoethoxyethanol, trimethylaminoethylethanolamine, methylhydroxyethylpiperazine, and hydroxyethylmorpholine; and ether amines such as bis(dimethylaminoethyl)ether and ethylene glycol bis(dimethyl)aminopropyl ether. 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 for adding and dispersing the urethane monomer composition.

[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 process> In this step, the aqueous medium and the urethane monomer composition are supplied to a granulator 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 and desolvation process> 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 kept 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 process) 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 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 methods for measuring the various physical properties according to the present disclosure will be described.

[0080] (Stress when the urethane resin particles are compressed to 10% of their particle size) The stress when 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 measurements were carried out in a laboratory with an 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] Measurement is performed using a flat indenter with a strength of 0.072 mN / μm that is attached to the device.

[0084] The test is performed with a 40 μm indentation depth and a 0.5 μm / s indenter movement speed. 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 long and short diameters of the urethane resin particles, and the particle diameter D (μm) of the particles to be measured is calculated as [(long diameter + short diameter) / 2]. The volume average particle diameter (Dv) is measured using a "CDA-1000X" (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 carried out 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% can be 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 using a differential scanning calorimeter "Q2000" (manufactured by TA Instruments) in accordance with ASTM D3418-82. 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 performed at a temperature range of -80°C to 200°C at a heating rate of 10°C / min. During the measurement, the sample is heated to 200°C once, then cooled to -80°C, and then heated again. The glass transition temperature of the urethane resin particles is determined by the intersection of the line midway between the baselines before and after the specific heat change that appears during this second heating process and the differential thermal curve.

[0092] (F of the urethane resin particles s A, F s B, F s C measurement) Urethane resin particles F s A is a hydrogen nucleus as follows: 1 It was calculated from the results of pulsed NMR measurement using H as the measurement nucleus.

[0093] 1 g of urethane resin powder was placed in a sample tube and pulsed NMR measurement was performed 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: 2.78μsec 180°Pulse Length: 5.46μsec Acquisition scale: 1.5 to 4 msec (adjusted based on actual measured relaxation curve) ·Measurement temperature: 23℃

[0094] The obtained echo intensity curve was subjected to three-component automatic fitting using the 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 three-component separation is not possible, separate two components and similarly separate the component with the shorter relaxation time as component T 2s A is the component fraction F s A [%] was calculated.

[0096] Similarly, the echo intensity curve measured at a measurement temperature of 10°C is automatically fitted to three components using the 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 the 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 size of the urethane resin powder) The volume average particle size (Dv) of the urethane resin particles is calculated as follows. The measurement device used is a particle counting and analysis device "CDA-1000X" (manufactured by Sysmex Corporation) equipped with a 100 μm aperture tube and employing the pore electrical resistance method. 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.

[0103] (1) Pour approximately 150 ml of the electrolyte solution into a dedicated glass round-bottom beaker, set it on the sample stage, and stir with the stirring propeller at 500 rpm. Then, click "Blank Check Measurement" in the dedicated software to start the measurement and confirm that the count is less than 500. If the count is 500 or more, repeatedly clean the beaker and aperture.

[0104] (2) Approximately 30 ml of the above-mentioned aqueous electrolyte solution is placed in a 100 ml flat-bottom glass beaker, and approximately 0.3 ml of a dilution of Contaminon N (a 10% 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.) diluted approximately three times by mass with ion-exchanged water is added as a dispersant.

[0105] (3) Prepare an ultrasonic disperser "Ultrasonic Dispension System Tetra150" (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. Place approximately 3.3 L of ion-exchanged water in the ultrasonic disperser's water tank and add approximately 2 mL of Contaminon N to this water tank.

[0106] (4) Set the beaker (2) in the beaker fixing hole of the ultrasonic disperser, operate the ultrasonic disperser, and adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic solution in the beaker is maximized.

[0107] (5) While ultrasonic waves are irradiated into the electrolyte solution in the beaker from (4), approximately 10 mg of urethane resin particles are added little by little and dispersed. The ultrasonic dispersion process is then continued for another 60 seconds. During the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be between 10°C and 40°C.

[0108] (6) Using a pipette, add dropwise the electrolyte solution (5) containing dispersed urethane resin particles to the round-bottom beaker (1) placed in the sample stand, adjusting the measurement concentration to approximately 6%. Then, measurements are continued until the number of particles measured reaches 50,000.

[0109] (7) The measurement data is analyzed using the dedicated software provided with the device to calculate the volume average particle size (Dv).

[0110] (Measurement of the average circularity of the 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 used during calibration work.

[0111] 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 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, 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. 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 cooled appropriately 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.

[0112] For the measurements, the flow particle image analyzer described above equipped with an "UPlanApro" objective lens (10x magnification, 0.40 numerical aperture) was used, and the sheath liquid was a particle sheath "PSE-900A" (manufactured by Sysmex Corporation). 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.

[0113] Before starting the measurement, automatic focus adjustment is performed using standard latex particles (for example, Duke Scientific's "RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5200A" diluted with ion-exchanged water). After that, it is preferable to perform focus adjustment every two hours from the start of the measurement.

[0114] If the volume average particle size exceeds 40 μm and the average circularity cannot be calculated using the above method, observe the urethane resin powder with a scanning electron microscope and use the image processing software "ImageJ" to measure the projected area S, perimeter L, etc. of the urethane resin particles.

[0115] 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

[0116] The same procedure is carried out for 100 urethane resin particles, and the average value is taken as the average circularity.

[0117] (Analysis of the molecular structure of the urethane resin) The molecular structure of the urethane resin in the urethane resin particles was analyzed using 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.

[0118] [Pyrolysis GC / MS] ·Pyrolysis device: JPS-700 (Japan Analysis Industry) ·Decomposition temperature: 590℃ GC / MS equipment: Focus GC / ISQ (Thermo Fisher) Column: HP-5MS, length 60 m, inner diameter 0.25 mm, film thickness 0.25 μm ·Inlet temperature: 200℃ Flow pressure: 100kPa Split: 50mL / min MS ionization: EI Ion source temperature: 200℃ Mass Range 45-650

[0119] 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.

[0120] [ATR-IR] A Fourier transform infrared spectrometer (Spectrum One, manufactured by PerkinElmer) equipped with a universal ATR sampling accessory is used to measure and analyze the structure under the following conditions. ·Infrared light (λ=5μm) incident angle: 45° ATR crystal: Ge ATR crystal (refractive index = 4.0) Range Start: 4000cm -1 End: 650cm -1 (Ge ATR crystal) Duration Scan number: 16 Resolution: 4.00cm -1 Advanced: CO2 / H2O correction

[0121] [ 1 H-NMR] ·Measurement device: FT NMR device JNM-EX400 (manufactured by JEOL Ltd.) Measurement frequency: 400MHz Pulse condition: 5.0μs Frequency range: 10500Hz Number of times accumulated: 64 ·Measurement temperature: 30℃ Sample: 50 mg of the urethane resin powder is placed in a sample tube with an inner diameter of 5 mm, deuterated chloroform (CDCl3) is added as a solvent, and the mixture is dissolved in a thermostatic bath at 40°C.

[0122] obtained 1 The H-NMR chart is analyzed to perform structural analysis of the urethane resin.

[0123] 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. [Example]

[0124] 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.

[0125] <<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% by mass, to obtain an aqueous medium 1.

[0126] <Preparation of Urethane Monomer Composition 1> The following materials were placed in a plastic container compatible with a planetary centrifugal mixer (THINKY ARV-310P): 54.1 parts by mass of Kuraray Polyol C-3090 (poly[(3-methyl-1,5-pentanediol:1,6-hexanediol) carbonate], a polycarbonate polyol manufactured by Kuraray Co., Ltd., with a molecular weight of 3000 and an OHV of 20). Sannix NP-300 (Sanyo Chemical Industries, Ltd., propylene oxide-modified ethylenediamine OHV=151): 2.9 parts by weight Methyl ethyl ketone (MEK): 33.3 parts by weight

[0127] The mixture was mixed using a planetary centrifugal mixer at 2000 rpm for 60 seconds.

[0128] Next, the following materials were quickly weighed into the same container: Duranate TKA100 (Asahi Kasei Corporation, hexamethylene diisocyanate polyisocyanate (nurate) NCO% = 21.8): 43.0 parts by mass TOYO-CAT RX-5 (Tertiary amine catalyst manufactured by Tosoh Corporation): 2000 ppm (total amount of isocyanate and polyol)

[0129] Again, the mixture was mixed using a planetary centrifugal mixer at 2000 rpm and 0.2 kPa for 90 seconds to obtain urethane monomer composition 1.

[0130] 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.

[0131] <Granulation process> 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.

[0132] 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.

[0133] <Condensation and desolvation process> 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.

[0134] <Separation and purification process> After the solvent removal step was completed, the solid content was filtered off from the dispersion liquid 1, thoroughly washed with ion-exchanged water, and then vacuum dried at 30° C. for 24 hours to obtain urethane resin powder 1 containing urethane resin particles.

[0135] The physical properties and composition analysis results of the obtained urethane resin powder 1 are shown in Table 3.

[0136] <<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 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.

[0137] [Table 1]

[0138] 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] manufactured by 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)) manufactured by Kuraray Co., Ltd., polyester polyol, molecular weight 6000, OHV=19.7) TMP: Trimethylolpropane

[0139] [Table 2]

[0140] The symbols in Table 2 represent the following: 90SH-100: Metrose 90SH-100 (cellulose derivative manufactured by Shin-Etsu Chemical Co., Ltd.)

[0141] <Urethane resin powder 11> Art Pearl C300T manufactured by Negami Chemical Industrial Co., Ltd. was used as the urethane resin particles 11.

[0142] The physical properties of the urethane resin powder 11 are shown in Table 3.

[0143] <Urethane resin powder 12> Art Pearl U600T manufactured by Negami Chemical Industrial Co., Ltd. was used as the urethane resin particles 12.

[0144] The physical properties of the urethane resin powder 12 are shown in Table 3.

[0145] <Urethane resin powder 13> Art Pearl CE400T manufactured by Negami Chemical Industrial Co., Ltd. was used as the urethane resin particles 13.

[0146] The physical properties of the urethane resin powder 13 are shown in Table 3.

[0147] <Urethane resin powder 14> The following materials were weighed into a 1000 mL jacketed four-neck separable flask. Thermoplastic polyurethane elastomer (BASF Japan Ltd. "Elastollan" 1180A10, weight average molecular weight 130,000, soft segment content 88%) 17.5g 35.0 g of polyvinyl alcohol (Gohsenol GL-05, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., weight-average molecular weight 11,000) 297.5g of N-methyl-2-pyrrolidone as organic solvent

[0148] The separable flask was heated to 80°C and stirred at 450 rpm for 2 hours using a helical ribbon impeller 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, and a white dispersion 20 was obtained. The resulting 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. 300 g of ion-exchanged water was added to obtain a slurry 14. The resulting slurry 14 was freeze-dried to obtain a urethane resin powder 14.

[0149] The physical properties of the obtained urethane resin powder 14 are shown in Table 3.

[0150] [Table 3]

[0151] The symbols in Table 3 represent the following: PC: Polycarbonate skeleton PES: Polyester skeleton

[0152] 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 no physical property measurements or composition analysis were performed.

[0153] <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.

[0154] The evaluation results are shown in Table 4.

[0155] (Paint preparation) Urethane resin 100 parts by weight (Dainippon Ink and Chemicals, Inc., CRISBON NY-373) 100 parts by weight of each urethane resin powder High molecular weight silicone oil: 2 parts by mass (silicone oil, Shin-Etsu Silicone Co., Ltd. KP340) Fine particle silica 12 parts by weight (Nipsil E220, manufactured by Nippon Silica Kogyo Co., Ltd., average particle size: 1.5 μm) Solvent 1000 parts by weight (IPA / DMF / ethyl acetate mixture)

[0156] The above materials were thoroughly mixed to prepare a paint.

[0157] (Preparation of evaluation samples) The substrate was an olefin-based thermoplastic elastomer (a mixture of PP / PE / EPDM blended in a mixing ratio of 36 / 28 / 36) molded into a sheet with a thickness of 800 μm. The above paint was applied to the surface of the substrate so that the mass after drying was 20 g / m.2 After coating in the amount shown, the coating was dried in a hot air drying oven at 100°C for 3 minutes to prepare an evaluation sample.

[0158] <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 feel to the touch was evaluated to evaluate the environmental dependency. A: The difference in hardness between 10℃ and 40℃ is less than 0.20, and there is almost no difference in feel depending on the environment. B: The difference in hardness between 10°C and 40°C is more than 0.20 but less than 0.24, and there is a slight difference in feel depending on the environment. C: The difference in hardness between 10°C and 40°C is 0.25 or more but less than 0.30, and the feel varies depending on the environment. D: The difference in hardness between 10℃ and 40℃ is 0.30 or more, and the feel varies greatly depending on the environment.

[0159] <Stress when compressed 10% in an environment of 23°C and 50% RH> The stress measured when compressed by 10% in an environment of 23°C and 50% RH was evaluated according to the following evaluation criteria. A: 0.26mN or more and 0.38mN or less B: 0.25mN or more but less than 0.26mN, or 0.38mN or more but less than 0.50mN C: Less than 0.25 mN or greater than 0.50 mN

[0160] <Abrasion resistance> Five layers of gauze (Japanese Pharmacopoeia) were placed on the obtained evaluation sample under a certain load and 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 change in particle size and aspect ratio was less than 3.0%. B: The change in particle size and aspect ratio was 3.0% or more and less than 5.0%. C: The change in particle size and aspect ratio was 5.0% or more.

[0161] [Table 4]

[0162] The present disclosure relates to the following configurations.

[0163] (Configuration 1) A urethane resin powder containing urethane resin particles, 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 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; The glass transition temperature of the urethane resin particles is 0°C or lower. 1. A urethane resin powder characterized by:

[0164] (Configuration 2) In pulse NMR measurement of the urethane resin particles at a measurement temperature of 23°C, hydrogen nucleus 1 The spin-spin relaxation time T2 is measured by a solid echo method using H as the measurement nucleus, and an echo intensity curve A of the urethane resin particles is obtained. 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 called component T 2s A, The component T in the urethane resin particles 2s The component fraction of A is F s When A[%] is used, The component fraction F s 2. The urethane resin powder according to claim 1, wherein A is 15 or more and 90 or less.

[0165] (Configuration 3) In pulse NMR measurement of the urethane resin particles at a measurement temperature of 10°C, hydrogen nucleus 1The spin-spin relaxation time T2 is measured by a solid echo method using H as the measurement nucleus, and an echo intensity curve B of the urethane resin particles is obtained. 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 component T 2s Let B be The component T in the urethane resin particles 2s The component fraction of B is F s B [%], In pulse NMR measurement of the urethane resin particles at a measurement temperature of 40°C, hydrogen nucleus 1 The spin-spin relaxation time T2 is measured by a solid echo method using H as the measurement nucleus, and an echo intensity curve C of the urethane resin particles is obtained. 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 component T 2s Let C, 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 aspect 1 or 2, wherein C is 1.0 or more and 1.5 or less.

[0166] (Configuration 4) 4. The urethane resin powder according to any one of aspects 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.

[0167] (Configuration 5) 5. The urethane resin powder according to any one of aspects 1 to 4, wherein the urethane resin particles have an average circularity of 0.950 or more.

[0168] (Configuration 6) The urethane resin has a partial structure represented by the following formula (1):

[0169] [ka]

[0170] 6. The urethane resin powder according to any one of aspects 1 to 5, wherein

[0171] (Configuration 7) 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 difunctional polyol, and a trifunctional or higher polyol.

[0172] (Configuration 8) 8. The urethane resin particles according to claim 7, wherein the bifunctional polyol is a polycarbonate polyol.

[0173] (Configuration 9) 9. The urethane resin particles according to aspect 7 or 8, wherein the tri- or higher functional polyol is a tetra- or higher functional polyol.

[0174] (Configuration 10) 10. The urethane resin particles according to claim 9, wherein the tetrafunctional or higher polyol is ethylenediamine modified with propylene oxide.

[0175] (Configuration 11) 11. The urethane resin powder according to any one of aspects 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.

Claims

1. A urethane resin powder containing urethane resin particles, The urethane resin particles contain a urethane resin, 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; the glass transition temperature of the urethane resin particles is 0°C or lower; 1. A urethane resin powder characterized by:

2. In pulse NMR measurement of the urethane resin particles at a measurement temperature of 23°C, hydrogen nucleus １ The spin-spin relaxation time T with H as the measurement nucleus ２ Measurement is carried out by a solid echo method to obtain an echo intensity curve A of the urethane resin particles. 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 called component T ２ｓ Let A be The component T in the urethane resin particles ２ｓ The component fraction of A is F ｓ When A [%] is used, 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 nucleus １ The spin-spin relaxation time T with H as the measurement nucleus ２ Measurement is carried out by a solid echo method to obtain an echo intensity curve B of the urethane resin particles, 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 component T ２ｓ Let B be The component T in the urethane resin particles ２ｓ The component fraction of B is F ｓ B [%], In pulse NMR measurement of the urethane resin particles at a measurement temperature of 40°C, hydrogen nucleus １ The spin-spin relaxation time T with H as the measurement nucleus ２ Measurement is carried out by a solid echo method to obtain an echo intensity curve C of the urethane resin particles, 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 component T ２ｓ Let C, 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. 4. The urethane resin powder according to claim 1, 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): 【Chemistry 1】 The urethane resin powder according to any one of claims 1 to 3, having

7. 2. 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 tetrafunctional or higher polyol is ethylenediamine modified with propylene oxide.

11. 2. 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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