Polyurethane elastomer and polyurethane molded article

Abstract

Provided is a polyurethane elastomer having a matrix and a plurality of domains dispersed in the matrix, the polyurethane elastomer being characterized in that, in a specific molded body thereof, the number of domains contained is 10 to 77,000, the arithmetic mean value of the equivalent sphere diameter of the domains is 1.0 [mu] m to 30.0 [mu] m, the proportion of the total volume of the domains is 15% by volume to 45% by volume, and the number of domains contained in the specific molded body is 10 to 77,000. The relationship between the parameter A of the viscoelastic item of the indication domain and the parameter B of the viscoelastic item of the indication matrix is Alt; b, the micro rubber hardness and the strain after 5 seconds of deloading are both within specific ranges, and D / C is 1.0 to 5.0 if C (mass%) and D (mass%) are the respective ratios of the mass of the extract E1 to the mass of the extract E2.

Description

Technical Field

[0001] This disclosure relates to polyurethane elastomers and polyurethane molded articles. Background Technology

[0002] Polyurethane elastomers are used in a wide range of applications such as artificial and synthetic leather, coatings, paints, and adhesives. Typically, polyurethane elastomers consist of the reaction products of polyisocyanates and polyols, and are composed of hard segments derived from polyisocyanates and soft segments derived from polyols.

[0003] Based on differences in molecular chain structure, polyols used as raw materials for polyurethane elastomers are classified into polyether polyols, polyester polyols, and polycarbonate polyols, with the type of polyol selected based on desired performance. Polyurethane elastomers with a polycarbonate structure obtained from polycarbonate polyols exhibit excellent abrasion resistance. Furthermore, polyurethane elastomers are known to have superior heat resistance, weather resistance, and hydrolysis resistance compared to polyether or polyester elastomers.

[0004] Meanwhile, in polyurethane elastomers with a polycarbonate structure, strong intermolecular forces act between the polycarbonate structures, leading to a significant increase in the hardness of the polyurethane elastomer. Therefore, polyurethane elastomers with a polycarbonate structure are difficult to use in applications requiring low hardness.

[0005] Patent document 1 discloses a polyurethane elastomer comprising a matrix phase and a domain phase dispersed within the matrix phase, wherein the matrix phase comprises repeating structural units derived from polycarbonate diol, and the domain phase comprises repeating structural units derived from polyether.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2022-168829 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] The polyurethane elastomer disclosed in Patent Document 1 can achieve a combination of low hardness and abrasion resistance comparable to silicone elastomers, as well as a combination of low hardness and low compression set. However, the inventors have discovered that when the molded body containing the polyurethane elastomer is, for example, a component that is expected to be in long-term compressed contact with another component, such as a gripper in a robot chuck, substances that seep out from the molded body can adhere to the contact object.

[0011] At least one embodiment of the present disclosure relates to providing a polyurethane elastomer that provides a shaped body that is flexible but exhibits a small compressive strain and does not produce an exudate that adheres to other components even when crimped onto other components. At least one other embodiment of the present disclosure relates to providing a shaped body that is flexible but exhibits a small compressive permanent deformation and does not produce an exudate that adheres to other components even when crimped onto other components.

[0012] Solutions to problems

[0013] At least one embodiment of the present disclosure provides a polyurethane elastomer having a matrix and a plurality of domains dispersed within the matrix, wherein in a first shaped body composed of the polyurethane elastomer and having a cubic shape with one side measuring 100 μm, the number N of domains contained is 10 to 77,000; the arithmetic mean Da of the sphere equivalent diameter of the domains is 1.0 to 30.0 μm; the proportion V of the total volume of the domains in the first shaped body is 15 to 45% by volume; in a cross-section parallel to one surface of the first shaped body, as measured in a viscoelastic image taken with a scanning probe microscope, the relationship between the parameter A indicating the viscoelastic term of the domains and the parameter B indicating the viscoelastic term of the matrix is A < B; the micro rubber hardness of a second shaped body composed of the polyurethane elastomer at a temperature of 23°C is 20 to 50 degrees, and in an indentation test of the second shaped body using a nanoindenter at a temperature of 23°C, when a Vickers indenter is pressed into the second shaped body at a load rate of 10 mN / 30 seconds, a load of 10 mN is maintained for 60 seconds and then the load is released, the strain 5 seconds after releasing the load is 1.0 μm or less; when performing Soxhlet extraction for 4 hours on a third shaped body composed of the polyurethane elastomer at an extraction temperature of 80°C using acetone as an extraction solvent according to Japanese Industrial Standard (JIS) K6229:2015, and regarding the ratio of the mass of the resulting extract E1 to the mass of the third shaped body as C (mass%), and when performing Soxhlet extraction for 4 hours on the powder of the third shaped body having a mode diameter less than 1 μm at an extraction temperature of 80°C using acetone as an extraction solvent according to Japanese Industrial Standard (JIS) K6229:2015, and regarding the ratio of the mass of the resulting extract E2 to the mass of the powder as D (mass%), D / C is 1.0 to 5.0.

[0014] At least one embodiment of the present disclosure provides a polyurethane shaped body containing the polyurethane elastomer of the present disclosure.

[0015] Advantages of the invention

[0016] According to at least one embodiment of this disclosure, a polyurethane elastomer can be obtained that is flexible but exhibits small compressive strain and does not produce exudates adhering to other components even when pressed onto them. Furthermore, according to at least one embodiment of this disclosure, a molded body can be obtained that is flexible but exhibits small compression set and does not produce exudates adhering to other components even when pressed onto them. Attached Figure Description

[0017] Figure 1 This is an illustrative diagram showing the deformation of a urethane elastomer according to the present disclosure.

[0018] Figure 2 This is a schematic illustration of a method for manufacturing a urethane elastomer according to one embodiment of the present disclosure.

[0019] Figure 3 This is a schematic illustration of a method for manufacturing a urethane elastomer according to one embodiment of the present disclosure. Detailed Implementation

[0020] In this disclosure, unless otherwise stated, the symbols "from XX to YY" and "XX to YY" indicating a range of values ​​signify a range that includes the lower and upper limits of the range as endpoints. When a range of values ​​is described in segments, the upper and lower limits of the individual ranges can be arbitrarily combined. In this disclosure, for example, phrases such as "select at least one from the group consisting of XX, YY, and ZZ" include XX, YY, and ZZ; combinations of XX and YY; combinations of XX and ZZ; combinations of YY and ZZ; and combinations of XX, YY, and ZZ. When XX represents a group, multiple members can be selected from XX, and the same applies to YY and ZZ.

[0021] To evaluate the degree of exudation from the molded body of the polyurethane elastomer according to Patent Document 1, the inventors conducted a solvent extraction test on a polyurethane elastomer having a matrix and multiple domains dispersed within the matrix. Specifically, according to Japanese Industrial Standard (JIS) K6229:2015, a molded body made of the polyurethane elastomer according to Patent Document 1, measuring 25 mm in length, 10 mm in width, and 2 mm in thickness, was subjected to Soxhlet extraction for 4 hours at an extraction temperature of 80°C using acetone as the extraction solvent, and the ratio C of the mass of the obtained extract to the mass of the molded body (hereinafter also referred to as the solvent extraction rate) was evaluated. It is believed that a low solvent extraction rate C corresponds to low exudation from the molded body, and thus reduces adhesion to the contacting object. Therefore, the solvent extraction rate C of the polyurethane elastomer according to Patent Document 1 from the molded body is sufficiently low. However, as mentioned above, when the molded body of the polyurethane elastomer according to Patent Document 1 remains in contact with another object for a long time, exudation can produce substances that adhere to the other object.

[0022] Next, the inventors pulverized the molded polyurethane elastomer according to Patent Document 1 to obtain powder with a mode diameter of less than 1 μm. Solvent extraction tests were then performed on the powder in the same manner as described above, and the ratio of the mass of the extract to the mass of the powder (solvent extraction rate D) was evaluated. As a result, the solvent extraction rate D resulted in the extraction of approximately half the mass of the load component constituting the domain of the molded body. Based on this result, it was determined that the exudate observed from the molded polyurethane elastomer according to Patent Document 1 when held under compression for an extended period primarily originates from the domain. In this case, the domain imparts a hardness-reducing function to the polyurethane according to Patent Document 1 (paragraph 0018 of Patent Document 1).

[0023] Therefore, the inventors recognized that in order to solve the problem of suppressing leakage from the domain of the polyurethane molded body according to Patent Document 1 when it is compressed for a long time, it is crucial to reduce the ratio of solvent extraction rate D to solvent extraction rate C (hereinafter also referred to as "D / C") while maintaining the high flexibility and low compression set exhibited by the molded body of the polyurethane elastomer according to Patent Document 1.

[0024] Based on this understanding, the inventors conducted extensive research to reduce the D / C ratio without compromising compatibility with low hardness and abrasion resistance, as well as low hardness and low compression set. Therefore, it was discovered that polyurethane elastomers with the following structure contribute to achieving the above objectives.

[0025] That is, the polyurethane elastomer according to one embodiment of this disclosure has a matrix and a plurality of domains dispersed within the matrix. In a first molded body composed of the polyurethane elastomer and having a cubic shape with one side measuring 100 μm, the number N of the included domains is from 10 to 77,000. The arithmetic mean Da of the spherical equivalent diameters of the domains is from 1.0 μm to 30.0 μm, the proportion V of the total volume of the domains in the first molded body is from 15% to 45% by volume, and the relationship between parameter A, indicating the viscoelasticity of the domains, and parameter B, indicating the viscoelasticity of the matrix, as measured in a viscoelastic image taken with a scanning probe microscope, in a cross-section parallel to one surface of the first molded body, is A. <B。

[0026] Furthermore, the second molded body made of polyurethane elastomer has a micro rubber hardness of 20 to 50 degrees at a temperature of 23°C, and in the indentation test of the second molded body using a nano-indenter at a temperature of 23°C, when the Vickers indenter is pressed into the second molded body at a load rate of 10 mN / 30 seconds, the 10 mN load is maintained for 60 seconds and then the load is released, the strain after 5 seconds of load release is less than 1.0 μm.

[0027] Furthermore, when a third molded body made of polyurethane elastomer is subjected to Soxhlet extraction for 4 hours at an extraction temperature of 80°C using acetone as the extraction solvent, according to Japanese Industrial Standard (JIS) K6229:2015, and the ratio of the mass of the obtained extract E1 to the mass of the third molded body is considered as C (mass %), and when a powder with a modal diameter of less than 1 μm of the third molded body is subjected to Soxhlet extraction for 4 hours at an extraction temperature of 80°C using acetone as the extraction solvent, and the ratio of the mass of the obtained extract E2 to the mass of the powder is considered as D (mass %), the D / C ratio is 1.0 to 5.0.

[0028] The polyurethane elastomers and the like disclosed herein will be described in detail below with reference to preferred embodiments and by using the accompanying drawings. The embodiments described below are merely examples, and unless otherwise stated, this disclosure is not limited to these embodiments.

[0029] Polyurethane elastomers shall meet the following requirements (1-1) to (1-4).

[0030] Requirement (1-1): The polyurethane elastomer has a matrix and multiple domains dispersed within the matrix.

[0031] Requirement (1-2): In a cross-section parallel to one surface of a first molded body made of polyurethane elastomer and having a cubic shape with one side measured to be 100 μm, as measured in a viscoelastic image taken with a scanning probe microscope, the relationship between parameter A, indicating the viscoelastic term of the domain, and parameter B, indicating the viscoelastic term of the matrix, is A. <B。

[0032] In other words, the matrix-domain structure of the polyurethane elastomer is observed in a cross-section parallel to one surface of the molded body. The elastic modulus of the polyurethane elastomer matrix observed in the cross-section is greater than that of the domain.

[0033] Requirements (1-3): The micro rubber hardness of the second molded body made of polyurethane elastomer is 20 to 50 degrees at a temperature of 23°C.

[0034] Requirements (1-4): In the indentation test of the second molded body using a nano-indenter at a temperature of 23°C, when the Vickers indenter is pressed into the second molded body at a load rate of 10mN / 30 seconds, the load of 10mN is maintained for 60 seconds, and then the load is released. The strain after 5 seconds of load release is less than 1.0μm.

[0035] In polyurethane elastomers, the matrix is ​​endowed with the function of recovering from deformation. Furthermore, the domain is endowed with the function of reducing the hardness of the polyurethane elastomer. Such polyurethane elastomers exhibit both softness and rapid recovery from deformation.

[0036] Furthermore, typical polyurethane elastomers also exhibit a difference in elastic modulus between the so-called hard and soft segments. However, in typical urethane elastomers, the soft segments constitute the matrix, and the hard segments constitute the domains. It is believed that no polyurethane elastomer can maintain the flexibility associated with requirements (1-3) while simultaneously exhibiting the rapid recovery rate from deformation associated with the specifications of requirements (1-4).

[0037] Figure 1 A is a cross-sectional view of a polyurethane molded body 3 according to one embodiment of the present disclosure.

[0038] Figure 1 A schematic diagram shows a polyurethane elastomer matrix 31 and a plurality of domains 32 dispersed within the matrix 31, as observed in a cross section parallel to one surface of the molded body.

[0039] As described above, the polyurethane elastomer has a matrix 31 and domains 32 dispersed within the matrix. In other words, the urethane elastomer has a matrix-domain structure. The matrix exhibits higher elasticity than the domains.

[0040] Figure 1 A and Figure 1B is an illustrative diagram of the recovery from deformation of a polyurethane molded body 3 according to one embodiment of this disclosure. Figure 1 As shown in Figure A, multiple domains 32 are dispersed within the matrix 31. Because the domains 32 have lower elasticity than the matrix 31, when the polyurethane molded body 3 is compressed in the direction of arrow F, as... Figure 1 As shown in B, domain 32 deforms preferentially. Therefore, even though matrix 31 has high elasticity, the micro-rubber hardness of the polyurethane molded article can be reduced. Furthermore, when the polyurethane molded article is released from compression, the elasticity of matrix 31, as a continuous phase, allows the thickness of the molded article to quickly recover to its pre-compression thickness.

[0041] (Number of domains N)

[0042] In a first molded body composed of a polyurethane elastomer and having a cubic shape with one side measuring 100 μm, the number N of domains contained in the first molded body is from 10 to 77,000. The number N of domains can be from 100 to 77,000, or even 700 to 77,000. By keeping the number N of domains within these ranges, a flexible polyurethane elastomer exhibiting low compressive strain is obtained. Furthermore, the number N of domains can be adjusted by modifying the mixing conditions (shear force and time) during the preparation of the urethane prepolymer, or by adjusting the molecular weight and amount added of the polyol and polyisocyanate.

[0043] The number of domains N can be determined by three-dimensional measurement of the first molded body using FIB-SEM. Thermosetting polyurethane elastomers can be used directly as the first molded body, or thermosetting polyurethane elastomers processed into a predetermined shape using a slicing machine can be used as the first molded body.

[0044] FIB-SEM is a technique that uses a focused ion beam (FIB) device to process samples and then uses a scanning electron microscope (SEM) to observe the exposed cross-sections of the samples. To examine the three-dimensional structure, numerous photographs are taken through repeated processing and observation, and these SEM images are then used to perform 3D reconstruction using computer software. Reconstructing the sample structure into a three-dimensional image allows for examination of the three-dimensional structure.

[0045] The specific method used to measure the number of domains N is to acquire a three-dimensional image of the first shaped body at 60 nm intervals using a FIB-SEM (manufactured by FEI, Inc.). The number of domains N in the acquired image is then calculated using the 3D visualization and analysis software Avizo (registered trademark, manufactured by FEI, Inc.). A more detailed measurement method is described below.

[0046] (Da) is the arithmetic mean of the spherical equivalent diameter of the domain.

[0047] In a first molded body made of a polyurethane elastomer and having a cubic shape with one side measuring 100 μm, the arithmetic mean Da of the sphere equivalent diameters of the domains is from 1.0 μm to 30.0 μm. The arithmetic mean Da can be from 2.0 μm to 20.0 μm, or from 2.0 μm to 15.0 μm. By maintaining the arithmetic mean Da within these ranges, a flexible polyurethane elastomer that exhibits a small compressive strain is obtained. Further, the arithmetic mean Da can be adjusted by adjusting the mixing conditions (shearing force and time) during the preparation of the urethane prepolymer or the molecular weights and addition amounts of the polyol and the polyisocyanate.

[0048] The arithmetic mean Da can be determined by three-dimensional measurement of the first molded body using the above-described FIB-SEM. A specific measurement method is described below.

[0049] (Ratio V of the total volume of the domains in the first molded body)

[0050] In a first molded body made of a polyurethane elastomer and having a cubic shape with one side measuring 100 μm, the ratio V of the total volume of the domains in the first molded body is from 15 vol% to 45 vol%. Further, the ratio V of the total volume of the domains in the first molded body can be from 20 vol% to 45 vol%, from 25 vol% to 42 vol%, and preferably from 25 vol% to 41 vol%. By maintaining the ratio V of the total volume of the domains in the first molded body within the above ranges, a flexible polyurethane elastomer that exhibits a small compressive strain is obtained. Further, the ratio V of the total volume of the domains in the first molded body can be adjusted by adjusting the mixing conditions (shearing force and time) during the preparation of the urethane prepolymer or the molecular weights and addition amounts of the polyol and the polyisocyanate.

[0051] The ratio of the total volume of the domains in the first molded body can be determined by three-dimensional measurement of the first molded body using the above-described FIB-SEM. A specific measurement method is described below.

[0052] (Parameter indicating viscoelastic term)

[0053] In a first molded body made of a polyurethane elastomer and having a cubic shape with one side measuring 100 μm, in a cross section parallel to one surface of the first molded body, as measured in a viscoelastic image taken with a scanning probe microscope, the relationship between the parameter A indicating the viscoelastic term of the domains and the parameter B indicating the viscoelastic term of the matrix is A < B. In other words, the elastic modulus of the polyurethane elastomer matrix observed in the cross section is greater than the elastic modulus of the domains. This makes it easier to achieve both hardness and recovery from deformation.

[0054] The difference in relative elastic modulus between matrix 31 and domain 32 can be determined by cutting the first shaped body to obtain a thin section and measuring it using a scanning probe microscopy (SPM / AFM). An example of a scanning probe microscopy that can be used is the "S-Image" (product name) manufactured by Hitachi High-Tech Science Corporation. Furthermore, examples of means for sectioning include a sharp razor, a microtome, and focused ion beam (FIB) technology. In this disclosure, a microtome is used.

[0055] The location used for preparing the slices is a freely chosen cutting surface parallel to one surface of a cubic first-shaped body with one side measuring 100 μm. The observation area for the viscoelastic image on the cutting surface is a freely chosen 50 μm square region.

[0056] The measurement mode for viscoelastic imaging using SPM is the viscoelastic dynamic force mode (VE-DFM). Furthermore, a silicon microcantilever for DMF (“SI-DF3”, manufactured by Hitachi High-Tech Science Corporation, spring constant = 1.9 N / m) is used. The scanning frequency is 0.5 Hz. VE-DFM is one of the measurement modes of SPM (Scanning Probe Microscopy). Using VE-DFM, surface topography images can be obtained while controlling the distance between the probe and the sample being measured, so as to maintain constant cantilever vibration and amplitude under conditions of cantilever resonance.

[0057] After acquiring the viscoelastic images, parameters indicating the viscoelastic term were calculated for each observation region, with 10 points in the matrix and 10 points in the domain. Their arithmetic mean was used as parameter A, indicating the viscoelastic term of the domain, and parameter B, indicating the viscoelastic term of the matrix. Parameters A and B were measured in mV, with larger values ​​indicating higher elasticity.

[0058] The ratio of parameter A to parameter B (A / B) is preferably 0.65 or less, but can also be 0.50 or less, or 0.40 or less. A smaller A / B ratio results in a greater difference in viscoelasticity between the matrix and the domain, making it easier to achieve both stiffness and recovery from deformation. There is no particular lower limit for the A / B ratio, but a smaller ratio is better. Specifically, for example, a ratio of 0.10. For example, A / B is preferably 0.10 to 0.65, 0.10 to 0.50, or 0.10 to 0.40.

[0059] Parameters A and B can be adjusted, for example, by changing the elastic modulus of the domain and the matrix. The elastic modulus of the matrix can be adjusted by the molecular weight, bonding type, and amount of the polyol or polyisocyanate. The elastic modulus of the domain can be adjusted by the molecular weight, bonding type, and amount of the polyol or polyisocyanate, or by adding a chain extender such as a polyol.

[0060] The value of parameter A is not particularly limited, but can be, for example, 50mV to 120mV or 60mV to 110mV. Similarly, the value of parameter B is not particularly limited, but can be, for example, 190mV to 310mV or 210mV to 290mV.

[0061] (Micro rubber hardness of the molded body)

[0062] The second molded body, composed of polyurethane elastomer, has a microrubber hardness of 20 to 50 degrees at a temperature of 23°C. Here, the second molded body is a cubic molded body with one side measuring 2 mm. If the sample thickness is less than 2 mm, a cubic second molded body with one side measuring 2 mm is obtained by stacking in the thickness direction. A microrubber hardness below 50 degrees results in good flexibility and low hardness. A microrubber hardness above 20 degrees results in high mechanical strength and good wear resistance. The microrubber hardness is preferably 25 to 50 degrees, more preferably 30 to 50 degrees.

[0063] The hardness of microrubber can be adjusted by modifying the elastic modulus of the matrix and the matrix-domain ratio. Specifically, increasing the elastic modulus of the matrix increases the hardness of the microrubber.

[0064] The micro-rubber hardness was determined as follows. The measurement point was approximately at the center of a freely chosen surface of a cubic second-shaped body with one side measuring 2 mm. The micro-rubber hardness was measured using a micro-rubber hardness tester (product name: MD-1capa; manufactured by Kobunshi Keiki Co., Ltd.; indenter: type A (cylindrical, diameter 0.16 mm, height 0.5 mm, outer diameter 4 mm, inner diameter 1.5 mm); measurement mode: peak hold mode) at a temperature of 23°C. When the sample thickness was less than 2 mm, the measurement point was approximately at the center of one surface of the second-shaped body, where the micro-rubber hardness could be measured along the thickness direction of the second-shaped body sample.

[0065] In addition, the second molded body can be made directly from thermosetting polyurethane elastomer, or the thermosetting polyurethane elastomer can be cut into the desired shape using scissors to form the second molded body.

[0066] (From the restorative properties of deformation)

[0067] In an indentation test of the second molded body using a nano-indenter at 23°C, when the Vickers indenter is pressed into the second molded body at a load rate of 10 mN / 30 seconds, the 10 mN load is maintained for 60 seconds, and then the load is released. The strain 5 seconds after the load is released is less than 1.0 μm. The strain 5 seconds after the load is released is preferably less than 0.8 μm, more preferably less than 0.7 μm, and even more preferably less than 0.6 μm. There is no particular limitation on the lower limit of the strain 5 seconds after the load is released, but it is typically 0.0 μm, and can be 0.1 μm. Examples of preferred values ​​include 0.0 μm to 1.0 μm, 0.0 μm to 0.8 μm, 0.0 μm to 0.7 μm, and 0.1 μm to 0.6 μm.

[0068] By maintaining the strain within the aforementioned range 5 seconds after the load is released, the polyurethane elastomer exhibits a rapid recovery rate from deformation.

[0069] The strain 5 seconds after load release can be adjusted by changing the type of matrix resin, the number of domains, and the domain size.

[0070] The strain value after 5 seconds of load release was determined as follows. The measurement point was approximately at the center of a freely chosen surface of a cubic second-shaped body with a side measurement of 2 mm. An indentation test was performed at 23°C using a nano-indenter (product name: Fischerscope HM2000, manufactured by Fischer Instruments, a four-cornered pyramidal Vickers indenter with a 136° relative angle). The Vickers indenter was pressed into the second-shaped body at a load rate of 10 mN / 30 seconds and maintained at 10 mN for 60 seconds. The load was then released at 10 mN / 30 seconds, and the strain value was measured 5 seconds after load release.

[0071] In addition, the second molded body can be made directly from thermosetting polyurethane elastomer, or the thermosetting polyurethane elastomer can be cut into the desired shape using scissors to form the second molded body.

[0072] (Solvent extraction rate C and solvent extraction rate of powder D)

[0073] When a third molded body made of polyurethane elastomer is subjected to Soxhlet extraction for 4 hours at an extraction temperature of 80°C using acetone as the extraction solvent, according to Japanese Industrial Standard (JIS) K6229:2015, and the ratio of the mass of the obtained extract E1 to the mass of the third molded body is considered as C (mass %), and when a powder with a modal diameter of less than 1 μm of the third molded body is subjected to Soxhlet extraction for 4 hours at an extraction temperature of 80°C using acetone as the extraction solvent, and the ratio of the mass of the obtained extract E2 to the mass of the powder is considered as D (mass %), the D / C ratio is 1.0 to 5.0. Here, the length of the third molded body is 25 mm, the width is 10 mm, and the thickness is 2 mm. Furthermore, the D / C ratio is preferably 1.5 to 4.5, more preferably 1.5 to 3.0.

[0074] As described above, by ensuring the D / C ratio is within the aforementioned range, a polyurethane elastomer can be obtained that is flexible yet exhibits low compressive strain and does not produce exudates adhering to other components, even when pressed onto them. The D / C ratio can be adjusted by adjusting either the value of C or the value of D, as described below.

[0075] (Solvent extraction rate C)

[0076] The solvent extraction rate C of polyurethane elastomers was determined by Soxhlet extraction.

[0077] First, polyurethane elastomer was shaped into a molded body using a mold for producing 2mm thick sheets. Then, the molded body was cut into slices 25mm long, 10mm wide, and 2mm thick to obtain a third molded body. When the sample thickness was less than 2mm, sufficient samples were prepared to form a 2mm thick layer upon stacking, and the samples were stacked to form a 2mm thick layer. Then, according to Japanese Industrial Standard (JIS) K6229:2015, the third molded body was subjected to Soxhlet extraction at an extraction temperature of 80°C for 4 hours using acetone as the extraction solvent. The solvent extraction rate C (mass %) was calculated as the ratio of the mass of the obtained extract E1 to the mass of the third molded body.

[0078] The value of solvent extraction rate C is not particularly limited, but is preferably 2.2% to 4.5% by mass, more preferably 2.3% to 3.5% by mass, and even more preferably 2.3% to 3.0% by mass. Keeping this value within the above range makes it easier to achieve D / C values ​​within the above range.

[0079] The solvent extraction rate C can be adjusted by the type and amount of catalyst added, as well as the type of matrix resin.

[0080] (Solvent extraction rate D of the powder)

[0081] The solvent extraction rate D of the powder was determined by Soxhlet extraction.

[0082] First, a polyurethane elastomer is shaped into a molded body using a mold for producing 2mm thick sheets. Then, the molded body is cut into slices 25mm long, 10mm wide, and 2mm thick using scissors to obtain a third molded body. The third molded body is then pulverized while sandwiched between filter paper to obtain a powder, and the solvent extraction rate D of the powder is determined in the same manner as the solvent extraction rate C described above. Examples of pulverization methods include cryogenic pulverization and pulverization using a press; however, pulverization using a press with filter paper is preferred because it makes it easier to fix the viscous material.

[0083] As a specific pulverization method, the aforementioned third-shaped body was sandwiched between two Kiriyama funnel filter papers 5B, then sandwiched between two degreased aluminum sheets, and pressed at 10 MPa for 1 minute using a 50-ton press (product name: PEF 5041, manufactured by Kansai Roll Co., Ltd.) preheated to 130°C. After releasing the load, the aluminum sheets were removed, and the pulverized third-shaped body sandwiched between the two Kiriyama funnel filter papers was folded and placed in a Soxhlet cylindrical filter paper. The solvent extraction rate D of the powder was determined in the same manner as the solvent extraction rate C described above.

[0084] To determine the mode diameter of the powder, a laser diffraction / scattering particle size distribution analyzer was used because it is compatible with the drying method and allows for simple measurements.

[0085] Specifically, a laser diffraction / scattering particle size distribution analyzer (product name: Partica LA-960V2, manufactured by Horiba, Ltd.) equipped with a drying measurement unit is used to measure the particle size distribution and determine the particle size exhibiting the maximum peak (mode diameter). The mode diameter represents the size of the pulverized material.

[0086] The solvent extraction rate D of the powder is not particularly limited, but is preferably 3.0% to 20.0% by mass, more preferably 4.0% to 17.0% by mass, even more preferably 4.3% to 11.0% by mass, and particularly preferably 4.3% to 7.0% by mass. Keeping this value within the above range makes it easier to achieve D / C values ​​within the above range.

[0087] The solvent extraction rate D of the powder can be adjusted by changing the type and amount of chain extender (e.g., polyol) and catalyst.

[0088] The number-average molecular weight of extract E2 obtained by Soxhlet extraction of powder obtained in a manner similar to that used to determine the solvent extraction rate D of the powder is preferably 2,000 to 100,000, more preferably 2,500 to 100,000, and even more preferably 5,000 to 100,000. Within the above range, a flexible polyurethane elastomer exhibiting low compressive strain is obtained. Furthermore, the number-average molecular weight of extract E2 can be adjusted by changing the material constituting the domain. A method for measuring the number-average molecular weight of extract E2 is described below.

[0089] The number average molecular weight of extract E2 can be, for example, 2,000 to 50,000, or 2,500 to 30,000.

[0090] The viscosity of extract E2 obtained by Soxhlet extraction of the powder obtained in a manner similar to that used to determine the solvent extraction rate D of the powder is preferably below 10,000 mPa·s. There is no particular lower limit, but for example, a viscosity of 1000 mPa·s to 10,000 mPa·s is preferred, 1200 mPa·s to 10,000 mPa·s is more preferred, and 2000 mPa·s to 10,000 mPa·s is even more preferred. By maintaining the viscosity within these ranges, a flexible polyurethane elastomer with low compressive strain can be obtained. Furthermore, the viscosity of extract E2 can be adjusted by changing the material constituting the domain. A method for measuring the viscosity of extract E2 is described below.

[0091] (Abrasion resistance)

[0092] When a ball-on-disk abrasion test conforming to JIS R1613:2010 is performed on the surface of a sheet-shaped abrasion specimen made of polyurethane elastomer and measured to be 30 mm in length, 30 mm in width, and 2 mm in thickness, under the following conditions (1) to (6), the mass loss rate of the abrasion specimen is preferably 10.0% by mass or less, more preferably 5.0% by mass or less, even more preferably 2.0% by mass or less, still more preferably 1.0% by mass or less, and particularly preferably 0.5% by mass or less. Abrasion resistance is improved by satisfying the above range.

[0093] (1) Ball

[0094] Material: Stainless steel

[0095] Diameter: 10mm

[0096] (2) Load: 100g

[0097] (3) Environment: Temperature 23℃, 50%RH

[0098] (4) Time: 60 minutes

[0099] (5) Sliding circle diameter: 10mm

[0100] (6) Rotation speed of the disc on which the sample is placed: 300 rpm.

[0101] The abrasion test was conducted as follows. First, the mass of the abrasion specimen was measured. Next, the abrasion specimen was fixed with double-sided tape so that its center was approximately positioned at the center of the sliding disc of the ball-on-disk friction and wear tester (product name: HEIDON Type: 20, manufactured by Shinto Chemical Co., Ltd.). At this point, the surface of the abrasion specimen in the thickness direction was placed in contact with the sliding disc. Next, the indenter composed of the aforementioned balls was pressed onto the center of the abrasion specimen with a load of 100g, and the abrasion specimen was rotated and slid at a sliding circle diameter of 10mm and a rotation speed of 300rpm for 60 minutes. After 60 minutes, the test was stopped, the abrasion debris and double-sided tape were removed, and the mass of the specimen was measured. The mass loss rate (mass %) was calculated from the mass of the specimen before and after the abrasion test. Here, the surface in the thickness direction of the abrasion specimen refers to the 30mm square surface of the abrasion specimen, which is 30mm in length and 30mm in width.

[0102] The mass loss rate of the abrasion specimen can be adjusted by changing the type of matrix resin, the number of domains, and the domain size.

[0103] (Polyurethane elastomer material)

[0104] Polyurethane elastomer materials will now be described. As previously mentioned, the polyurethane elastomer has a matrix 31 and a plurality of domains 32 dispersed within the matrix. That is, the urethane elastomer has a matrix-domain structure.

[0105] Preferably, the matrix 31 has a structure that can increase the deformation recovery rate, and the domain 32 has a structure that helps to suppress the increase of micro-rubber hardness.

[0106] The matrix 31 of this type of polyurethane elastomer preferably has a first structure (polycarbonate structure) represented by formula (1). The matrix has at least one polycarbonate structure represented by formula (1), preferably multiple structures. When the matrix has multiple polycarbonate structures represented by formula (1), the polycarbonate structures can be repeating structural units. Furthermore, the first structure represented by formula (1) is composed of R 1 The alkylene groups representing 3 to 9 carbon atoms can have straight-chain or branched structures, but branched structures are preferred.

[0107] [Chemical Formula 1]

[0108]

[0109] (In equation (1), R) 1 (Refers to alkylene groups having 3 to 9 carbon atoms (preferably 6 to 9)).

[0110] Polyurethanes obtained by reacting polyols with polycarbonate structures (polycarbonate polyols) with polyisocyanates exhibit high elasticity due to the strong intermolecular forces between the carbonate groups. Therefore, such polyurethanes are a preferred component of matrix 31.

[0111] Furthermore, due to R 1 It is an alkylene group with 3 to 9 carbon atoms, thus ensuring incompatibility with domains containing a second structure (polyether structure) represented by formula (2) below, thereby allowing clear phase separation between the matrix and the domain. This more reliably ensures the dual functionality of the polyurethane elastomer: flexibility and rapid recovery from deformation.

[0112] Furthermore, when R 1 When the alkylene group has a branched structure with 3 to 9 carbon atoms, the intermolecular forces between the carbonate groups are appropriately suppressed to prevent the matrix from becoming overly elastic.

[0113] R 1 Examples include -(CH2). m -(m=3 to 9, preferably 6 to 9), -CH2C(CH3)2CH2-, -CH2CH(CH3)CH2-, and -(CH2)2CH(CH3)(CH2)2-. These can be used alone or in combination of at least two.

[0114] The number-average molecular weights of the polycarbonates and polyols described below can be calculated using the hydroxyl value (mg KOH / g) and valence using the following formula. For example, the number-average molecular weight of a polyether polyol with a hydroxyl value of 56.1 mg KOH / g and a valence of 2 can be calculated as 2000.

[0115] Number average molecular weight = 56.1 × 1000 × valence / hydroxyl value

[0116] The elastic modulus of the matrix can be adjusted, for example, by increasing the crosslinking density using polyisocyanate trimer compounds or polymer compounds. Typically, increasing the elastic modulus increases the microrubber hardness of the polyurethane elastomer. However, in this disclosure, multiple low-elasticity domains are dispersed within the matrix, thereby preventing excessive increases in hardness.

[0117] Domain 32 preferably includes a second structure (polyether structure) represented by formula (2). The domain has at least one polyether structure represented by formula (2), preferably multiple. When the domain has multiple polyether structures represented by formula (2), the polyether structure can be a repeating structural unit. Furthermore, the structural unit represented by formula (2) is composed of R... 2 The alkylene groups representing 3 to 6 carbon atoms can have straight-chain or branched structures, but branched structures are preferred.

[0118] [Chemical Formula 2]

[0119]

[0120] (In equation (2), R) 2 (Refers to alkylene groups having 3 to 6 carbon atoms (preferably 3 to 4)).

[0121] Polyethers exhibit low elastic modulus due to the weak intermolecular forces between ether groups. Therefore, polyethers are preferred as domain components.

[0122] Furthermore, when R 2 When the carbon atoms are 3 to 6 alkylene groups, incompatibility with a matrix having a polycarbonate structure represented by formula (1) is ensured, resulting in clear phase separation between the matrix and the domain, which is preferred.

[0123] R 2 Examples include -(CH2). m -(m=3 to 6), -CH2CH(CH3)-, -CH2C(CH3)2CH2-, -CH2CH(CH3)CH2-, and -(CH2)2CH(CH3)CH2-. These can be used alone or in combination of at least two.

[0124] The number-average molecular weight of the polyether structure represented by formula (2) is preferably from 1,000 to 50,000. More preferably, it is from 1,200 to 30,000. A number-average molecular weight of 1,000 or more is preferred because the incompatibility between the domain and the matrix comprising the polycarbonate structure represented by formula (1) is improved, resulting in clear phase separation between the matrix and the domain. Furthermore, a number-average molecular weight of 50,000 or less is preferred because it promotes domain formation and stabilizes the phase separation morphology.

[0125] The domain preferably has a third structure, and the third structure is preferably formed by the addition polymerization of glycerol and at least one selected from the group consisting of ethylene oxide and propylene oxide. That is, the third structure is preferably an addition polymer of glycerol and at least one selected from the group consisting of ethylene oxide and propylene oxide. When the domain has a third structure, the three-branched structure derived from glycerol forms a three-dimensional cross-linked structure, and even if the ends are unreacted, they will entangle with the cross-linked portions of the same matrix due to their three-dimensional expansion, thus preventing the leakage of components derived from the domain.

[0126] The chemical structure of the matrix and domains can be analyzed using spectrometers such as AFM infrared spectrometers, micro-infrared spectrometers, micro-Raman spectrometers, or mass spectrometers.

[0127] (Manufacturing method of polyurethane elastomer)

[0128] An example of the above-mentioned method for manufacturing polyurethane elastomers includes the steps (i) to (iii).

[0129] Step (i): reacting a first polyether having at least two isocyanate groups with a first polycarbonate polyol having at least two hydroxyl groups to obtain a urethane reactive emulsifier having at least two hydroxyl groups.

[0130] Step (ii): The step of obtaining a dispersion, wherein droplets containing at least a portion of a urethane reactive emulsifier are dispersed in a second polycarbonate polyol.

[0131] Step (iii): The step of preparing a mixture for forming a polyurethane elastomer, the mixture comprising the dispersion obtained in step (ii) and a polyisocyanate having at least two isocyanate groups, and then reacting the urethane reactive emulsifier, the second polycarbonate polyol and the polyisocyanate in the mixture for forming the polyurethane elastomer.

[0132] use Figure 2 Explain the steps of the manufacturing method described above.

[0133] In step (i), a first polyether 51 having at least two isocyanate groups is mixed with a first polycarbonate polyol 52 having at least two hydroxyl groups. The isocyanate groups and hydroxyl groups in the mixture are reacted in the presence of a catalyst to link them together via urethane bonds to obtain a urethane reactive emulsifier 53 having at least two hydroxyl groups. The urethane reactive emulsifier is a reactive emulsifier having urethane bonds.

[0134] In step (ii), the urethane reactive emulsifier 53 obtained in step (i) is dispersed in a second polycarbonate polyol 55. The segments derived from the first polyether 51 contained in the urethane reactive emulsifier 53 are incompatible with the second polycarbonate polyol 55 and form droplets 54. Simultaneously, in the second polycarbonate polyol 55, droplets 54 containing segments derived from the first polyether constituting part of the urethane reactive emulsifier are uniformly and stably dispersed by segments derived from the first polycarbonate polyol 52 contained in the urethane reactive emulsifier 53. Thus, a dispersion is obtained in which droplets 54 containing segments of the first polyether 51 derived from the urethane reactive emulsifier 53 are dispersed in the second polycarbonate polyol 55. For illustrative purposes, steps (i) and (ii) are described separately; however, these steps may also be implemented as a sequential series of steps.

[0135] In step (ii), the second polycarbonate polyol 55 to disperse droplets 54 can be the unreacted portion of the first polycarbonate polyol used in step (i) that has not yet reacted with the first polyether. That is, by using an excess of the first polycarbonate polyol relative to the first polyether in step (i), the dispersion described in step (ii) can be obtained, wherein the urethane reactive emulsifier 53 is dispersed in the excess first polycarbonate polyol, i.e., the second polycarbonate polyol 55. Even when an excess of the first polycarbonate polyol is used, additional polycarbonate polyol (the second polycarbonate polyol) can be added as a dispersion medium for the urethane reactive emulsifier. In this case, the additional polycarbonate polyol can have the same chemical composition as the first polycarbonate polyol used in step (i), or it can have a different chemical composition.

[0136] Simultaneously, if the first polycarbonate polyol and the first polyether react in equivalence in step (i) and the first polycarbonate polyol is completely consumed, a dispersion is prepared in step (ii) by using a new polycarbonate polyol as the second polycarbonate polyol. In this case, the polycarbonate polyol used as the second polycarbonate polyol may have the same chemical composition as the first polycarbonate polyol, or it may have a different chemical composition.

[0137] Finally, in step (iii), a polyurethane elastomer forming mixture is prepared, comprising the dispersion prepared in step (ii) and a polyisocyanate 56 having at least two isocyanate groups. Next, the terminal hydroxyl groups of the urethane reactive emulsifier 53, the hydroxyl groups of the second polycarbonate polyol 55, and the isocyanate groups of the polyisocyanate 56 in the polyurethane elastomer forming mixture are reacted. This forms a network structure via urethane bonds, thereby curing the polyurethane elastomer forming mixture to obtain a polyurethane elastomer. The resulting polyurethane elastomer 500 has a matrix-domain structure, comprising domains 32 of polyether derived from the first polyether 51 dispersed in a matrix 31 containing a urethane elastomer having polycarbonate derived from the first polycarbonate polyol 52 and the second polycarbonate polyol 55. Furthermore, the domains 32 are primarily composed of a polyether structure, and components with substantially no cross-linked structures (i.e., liquid components) can be present within the domains. This allows the domains in the polyurethane elastomer to have a low elastic modulus.

[0138] Furthermore, the domains are not simply liquid components encapsulated within the matrix; rather, the domains and the matrix are considered to be chemically bonded at their boundary portions via urethane bonds. Therefore, when the load applied to the polyurethane elastomer is released, the recovery of the domains from deformation can be synchronized with the recovery of the matrix from deformation.

[0139] As described above, the almost liquid domains are essentially devoid of internal cross-linking structures. Therefore, when a load is applied to a polyurethane elastomer, the deformed domains are unlikely to recover autonomously from deformation. However, in polyurethane elastomers, the domains are considered to be chemically bonded to the matrix at their boundary portions. This allows the domains to recover from deformation along with the matrix. Therefore, even when the polyurethane elastomer is repeatedly subjected to loading and unloading, stable deformation (deformation amount) and stable recovery from that deformation can be achieved.

[0140] In steps (i) and (ii) above, the polyether, which would otherwise be difficult to disperse stably and uniformly in the polyol due to low compatibility, is able to be dispersed stably. Specifically, the first polyether 51 is reacted with the first polycarbonate polyol 52 to produce a urethane reactive emulsifier 53. As a result, in this step, a dispersion is obtained in which the polyether segments derived from the first polyether 51 are stably and uniformly dispersed in the second polycarbonate polyol. This facilitates the manufacture of a polyurethane elastomer in which domains 32, having high roundness, micron-sized dimensions, and a relatively uniform size distribution, are dispersed within the matrix 31.

[0141] Another method for mixing materials with low compatibility is exemplified by using high shear forces to mix and disperse the materials. However, this method subjectes the polyether to high shear stress, resulting in distorted domain shapes and reduced roundness, and can also lead to non-uniform domain sizes. Furthermore, the dispersion is unstable, and domain aggregation occurs within a relatively short time. Moreover, incompatibility between the polyether and the polycarbonate polyol cannot be guaranteed. Consequently, phase separation between the matrix and domains of the resulting polyurethane elastomer is unclear. This makes it difficult to obtain the polyurethane elastomers disclosed herein that provide elastomers with flexibility and excellent recovery from deformation.

[0142] The first polyether has at least two isocyanate groups. Furthermore, the first polyether preferably has a second structure represented by formula (2). The first polyether can be obtained, for example, by reacting a polyether polyol having at least two hydroxyl groups and a second structure represented by formula (2) (corresponding to the “first polyol” in the examples) with a polyisocyanate having at least two isocyanate groups.

[0143] Examples of polyether polyols include polyether polyols containing alkylene structures, such as copolymers of polypropylene glycol, polytetramethylene glycol, tetrahydrofuran and neopentyl glycol, copolymers of tetrahydrofuran and 3-methyltetrahydrofuran, and random or block copolymers of these polyalkylene glycols. These can be used alone or in combination of at least two.

[0144] Here, a combination of difunctional and trifunctional polyether polyols is preferred as a polyether polyol having at least two hydroxyl groups and a second structure represented by formula (2), because it inhibits the exudation of domain-derived substances onto the surface of the molded polyurethane elastomer and makes it easier to adjust the D / C ratio to the range of 1.0 to 5.0. Figure 3 Explain the reasons.

[0145] When a polyether polyol having two hydroxyl groups, a polyether polyol having three hydroxyl groups, and a polyisocyanate having at least two isocyanate groups are combined as a polyether polyol, the reaction with the polyisocyanate having at least two isocyanate groups produces a first polyether 51 having two isocyanate groups at its end and a first polyether 57 having three isocyanate groups at its end.

[0146] In step (i), these first polyethers are reacted with a first polycarbonate polyol 52 having at least two hydroxyl groups to produce a urethane reactive emulsifier 53 having at least two hydroxyl groups. The resulting urethane reactive emulsifier 53 has a three-dimensional network structure. In the polyurethane elastomers obtained by using such urethane reactive emulsifiers in subsequent steps (ii) and (iii), the amount of polyol in the domains not bound to the matrix can be reduced. Therefore, the combined use of bifunctional and trifunctional polyether polyols as polyether polyols reduces the D value, thereby making it easier to adjust the D / C ratio in the range of 1.0 to 5.0.

[0147] Particularly suitable trifunctional polyether polyols are triol-type polypropylene glycol, triol-type polyethylene glycol, and copolymers of polyethylene oxide and polypropylene oxide, which are triol-type copolymers. Here, for example, triol-type polypropylene glycol refers to polypropylene glycol having three hydroxyl groups in its molecule.

[0148] Among polyether polyols, amorphous polyether polyols are preferred from the viewpoint of incompatibility with second polycarbonate polyols and the ability to achieve low hardness.

[0149] More preferably, the polyether polyol contains at least one selected from copolymers of polypropylene glycol, tetrahydrofuran and neopentyl glycol, and copolymers of tetrahydrofuran and 3-methyltetrahydrofuran.

[0150] The number average molecular weight of the polyether polyol is preferably from 1,000 to 50,000. More preferably, it is from 1,200 to 30,000. A number average molecular weight of 1,000 or higher is preferred because it ensures incompatibility with the polycarbonate polyol, resulting in clear phase separation between the matrix and domains in the obtained urethane elastomer. Furthermore, a number average molecular weight of 50,000 or lower is preferred because it promotes domain formation and stabilizes the phase separation morphology.

[0151] Examples of polyisocyanates that react with polyether polyols include pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, phenyl dimethyl diisocyanate, diphenylmethane diisocyanate, trimers (isocyanurates) or polymers of these polyisocyanates, urea-formyl polyisocyanates, biuret polyisocyanates, and water-dispersible polyisocyanates. These polyisocyanates can be used alone or in combination of at least two.

[0152] Among polyisocyanates, bifunctional isocyanates having two isocyanate groups are preferred because of their high compatibility with the first polyether and ease of adjustment of physical properties such as viscosity. More preferably, it includes at least one selected from hexamethylene diisocyanate, isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, xylene diisocyanate, and diphenylmethane diisocyanate. Among these, phenyl dimethyl diisocyanate is even more preferred.

[0153] In the reaction step of the polyether polyol with the polyisocyanate, the isocyanate index is preferably in the range of 1.2 to 5.0. Maintaining an isocyanate index within this range reduces the amount of component derived from the first polyether retained without forming a network structure, and also inhibits the leakage of liquid substances from the polyurethane elastomer. The isocyanate index refers to the ratio of the molar number of isocyanate groups in the isocyanate compound to the molar number of hydroxyl groups in the polyol compound ([NCO] / [OH]).

[0154] The first polyether obtained by reacting a polyether polyol with a polyisocyanate has a structure linked by urethane bonds formed by the reaction of hydroxyl groups with isocyanate groups. Its number-average molecular weight is preferably from 1,000 to 50,000, more preferably from 1,200 to 30,000.

[0155] The first polycarbonate polyol has at least two hydroxyl groups. It is also preferably a polycarbonate polyol having a first structure represented by formula (1). Examples of the first polycarbonate polyol include reaction products of polyols with phosgene and ring-opening polymerization products of cyclic carbonates (such as alkylene carbonates).

[0156] Examples of polyols include propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylene glycol, 1,3-tetramethylene glycol, 2-methyl-1,3-trimethylene glycol, 1,5-pentamethylene glycol, neopentyl glycol, 1,6-hexamethylene glycol, 3-methyl-1,5-pentamethylene glycol, 2,4-diethyl-1,5-pentamethylene glycol, glycerol, trimethylolpropane, trimethylolethane, cyclohexanediols (such as 1,4-cyclohexanediol), and sugar alcohols (such as xylitol and sorbitol).

[0157] Examples of alkylene carbonates include trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate.

[0158] The number-average molecular weight of the first polycarbonate polyol is preferably 500 to 10,000. More preferably, it is 700 to 8,000. A number-average molecular weight of 500 or more ensures incompatibility with the domains of the polyether containing the second structural unit represented by formula (2), resulting in clearer phase separation between the matrix and the domains. Furthermore, a number-average molecular weight of 10,000 or less can prevent excessive increase in viscosity in the first polycarbonate polyol.

[0159] The second polycarbonate polyol to be used in step (ii) can be any polycarbonate polyol listed above for the first polycarbonate polyol. As mentioned above, the first and second polycarbonate polyols can have the same chemical composition, or they can be different.

[0160] The polyisocyanate 56 having at least two isocyanate groups to be used in step (iii) may be the same as the polyisocyanate exemplified above as a raw material for the first polyether. These polyisocyanates may be used alone or in combination of at least two.

[0161] From the viewpoint of increasing the elastic modulus of the matrix, it is preferred that the polyisocyanate 56 includes polyisocyanates having at least three isocyanate groups among the polyisocyanates exemplified above, such as polyisocyanate trimer compounds (isocyanurates) or polymer compounds, urea-formate type polyisocyanates, or biuret type polyisocyanates.

[0162] More preferably, the polyisocyanate 56 includes at least one selected from the group consisting of pentamethylene diisocyanate trimer (isocyanurate), hexamethylene diisocyanate trimer (isocyanurate), diphenylmethane diisocyanate polymer, and polymeric MDI.

[0163] In the above, polymeric MDI is preferred. Polymeric MDI is a mixture of monomeric MDI and a high molecular weight polyisocyanate, and is represented by the following formula (A). Preferably, n in formula (A) is 0 to 4.

[0164] Commercially available polymeric MDIs can be used, examples of which include the Millionate MR series (manufactured by Tosoh Corporation) such as Millionate MR200 (trade name).

[0165] [Chemical Formula 3]

[0166]

[0167] As a polyisocyanate 56 having at least two isocyanate groups, it is preferred to use a polyisocyanate having at least three isocyanate groups, such as polymeric MDI, in combination with a difunctional isocyanate having two isocyanate groups. This combination allows for adjustment of the crosslinking density of the matrix, making it preferred from the viewpoint of achieving both low hardness and low compression set.

[0168] The catalyst can be a conventionally known urethane catalyst or an isocyanurate catalyst (isocyanate trimer catalyst). These can be used alone or in combination.

[0169] Examples of urethane catalysts include tin-based urethane catalysts such as dibutyltin dilaurate and stannous octanoate, and amine-based urethane catalysts such as triethylenediamine, tetramethylguanidine, pentamethyldiethylenetriamine, diethylimidazole, tetramethylpropylenediamine, N,N,N'-trimethylaminoethylethanolamine, 1,4-diazabicyclo[2.2.2]octane-2-methanol, and N,N-dimethylaminohexanol. These can be used alone or in combination. N,N-dimethylaminohexanol is particularly preferred for obtaining the polyurethane elastomers disclosed herein. Specifically, 1,4-diazabicyclo[2.2.2]octane-2-methanol and N,N-dimethylaminohexanol have hydroxyl groups that can react with isocyanates to reduce amine emissions. It is believed that the urethane catalytic activity of the amine segment decreases when the hydroxyl group reacts with isocyanate. In other words, it is believed that the higher the reactivity of the hydroxyl group with isocyanate, the lower its activity as a urethane catalyst. Furthermore, N,N-dimethylaminohexanol has lower reactivity of hydroxyl groups with isocyanates compared to 1,4-diazabicyclo[2.2.2]octane-2-methanol, and is considered less susceptible to the relatively reduced catalytic activity of urethanes when used in urethane reactions. Therefore, in step (i), the first polyether 51 having at least two isocyanate groups can react more effectively with the first polycarbonate polyol 52 having at least two hydroxyl groups. Therefore, in the polyurethane elastomer obtained in step (iii), the number of urethane bonds at the boundary portion between the domain and the matrix can be increased compared to when 1,4-diazabicyclo[2.2.2]octane-2-methanol is used as a catalyst. Therefore, using N,N-dimethylaminohexanol as a catalyst can further prevent domain components from penetrating to the surface of the polyurethane elastomer molded body, and is extremely effective in setting the D / C ratio in the range of 1.0 to 5.0.

[0170] In this disclosure, as described above, in order to reduce the amount D of exudate on the surface of the polyurethane elastomer molded body and adjust the D / C ratio to a range of 1.0 to 5.0, it is effective to employ at least one means selected from the group consisting of:

[0171] A combination of polyether polyols having two hydroxyl groups and polyether polyols having three hydroxyl groups is used as the raw material for the first polyether.

[0172] And N,N-dimethylaminohexanol was used as a catalyst.

[0173] Examples of isocyanurate catalysts include metal oxides such as Li₂O and (Bu₃Sn)₂O; hydrides such as NaBH₄; alkoxides such as NaOCH₃, KO-(t-Bu), and borates; amines such as N(C₂H₅)₃, N(CH₃)₂CH₂C₂H₅, and 1,4-ethylenepiperazine (DABCO); basic carboxylates such as HCOONa, Na₂CO₃, PhCOONa / DMF, CH₃COOK, (CH₃COO)₂Ca, basic soaps, and naphthenates; basic formates; and quaternary ammonium compounds such as ((R)₃-NR'OH)-OCOR". Here, Bu represents butyl, Ph represents phenyl, and R, R', and R" represent any alkyl group.

[0174] Furthermore, examples of catalyst combinations (co-catalysts) that can be used as isocyanurate catalysts include amine / epoxide, amine / carboxylic acid, and amine / alkylimide. These isocyanurate catalysts and catalyst combinations can be used alone or in combination.

[0175] In the manufacturing process of polyurethane elastomers, chain extenders (multifunctional low molecular weight polyols) may be used as needed. Examples of chain extenders include glycols with a number average molecular weight of less than 1000. Examples of such glycols include ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), dipropylene glycol (DPG), 1,4-butanediol (1,4-BD), 1,6-hexanediol (1,6-HD), 1,4-cyclohexanediol, 1,4-cyclohexanediol, terephthalic acid diol (terephthalic acid), and triethylene glycol.

[0176] In addition to diols, examples of chain extenders include polyols with a oxidation state of three or higher. Examples of polyols with a oxidation state of three or higher include trimethylolpropane, glycerol, pentaerythritol, and sorbitol. These can be used alone or in combination.

[0177] Additives can also be used as needed, such as foaming agents, microspheres, pigments, plasticizers, waterproofing agents, antioxidants, conductive agents, UV absorbers, and light stabilizers.

[0178] Polyurethane molded parts include polyurethane elastomers. For example, thermosetting polyurethane elastomers can be used directly as polyurethane molded parts.

[0179] Polyurethane molded articles can have foamed structures obtained by mechanical froth method or by foaming with chemical foaming agents or by adding microspheres.

[0180] Polyurethane molded parts can also be used in applications such as artificial muscles, artificial skin, synthetic leather, robot chucks, shoe soles, insoles, CMP polishing pads, stretchable electronics, flexible electronics, pressure sensors, elastic sensors, soft actuators, power generation components, speakers, and small pumps.

[0181] Example

[0182] The following examples further illustrate one embodiment of this disclosure. However, this disclosure is not limited to the following examples.

[0183] <Materials Used>

[0184] The materials used in the embodiments and comparative examples are listed below.

[0185] [Polyols]

[0186] [Table 1]

[0187]

[0188] In this table, Kuraray Polyol C-2090 (manufactured by Kuraray Co., Ltd.) is a polycarbonate polyol with a number-average molecular weight of 2000, a hydroxyl value of 56.3 mg KOH / g, and having structures corresponding to 1,6-hexanediol and 3-methyl-1,5-pentanediol. In other words, regarding the number of carbon atoms in the polycarbonate diol and polycarbonate polyol, for example, "6 (straight chain) + 6 (branched chain)" indicates R... 1 It contains both a straight-chain structure with 6 carbon atoms and a branched structure with 6 carbon atoms. Furthermore, Kuraray Polyol P-2050 is a polyester polyol having structures corresponding to adipic acid and 3-methyl-1,5-pentanediol. PREMINOL S3011, Actcol EP-950N, and PREMINOL 7012 are all triol-type polypropylene glycols.

[0189] [Polyisocyanates]

[0190] B-1: Phthalic dimethyl diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0191] B-2: Polymer MDI (Product Name: Millionate MR-200, manufactured by Tosoh Corporation)

[0192] [Cure catalyst]

[0193] C-1: N,N-Dimethylaminohexanol (Product name: Kaolizer No. 25, manufactured by Kao Corporation)

[0194] C-2: 1,4-diazabicyclo[2.2.2]octane-2-methanol (Product name: RZETA, manufactured by Tosoh Corporation)

[0195] <Evaluation>

[0196] The evaluation methods for the embodiments and comparative examples are described below.

[0197] [Evaluation 1: Confirmation of matrix-domain structure and component analysis]

[0198] Slices were prepared from the polyurethane elastomer using a slicer to obtain a first-formed cubic body with a side measurement of 100 μm. Mapping measurements were then performed using a three-dimensional micro-laser Raman spectrometer (product name: Nanofinder 30, manufactured by Tokyo Instruments Inc.). The measurement mode was EM (electron multiplication), and measurements were taken at 60 × 60 points at 500 nm intervals, obtaining data from 0 cm⁻¹. -1 Up to 400cm -1 The integral image obtained confirmed the presence of a matrix and multiple domains dispersed within the matrix in the elastic layer. Furthermore, the matrix and domains were clearly phase-separated.

[0199] Next, Raman spectra of the matrix and domain portions were measured from the integrated image. Measurements were performed using an Nd:YVO4 light source (wavelength 532 nm), a laser intensity of 240 μW, a 100x objective lens, a 300 gr / mm diffraction grating, a 100 μm pinhole diameter, a 30-second exposure time, and a single integration. The obtained Raman spectra confirmed that the matrix contained structures derived from polycarbonate urethane, and the domain contained structures derived from polypropylene glycol.

[0200] [Evaluation 2: Number of domains, sphere equivalent diameter, and overall volume ratio]

[0201] First, a cubic first-shaped body with one side measuring 100 μm was obtained in the same manner as Evaluation 1. Three-dimensional images of the first-shaped body were acquired using FIB-SEM (manufactured by FEI Inc.) at 60 nm intervals. The acquired images were then analyzed using the 3D visualization and analysis software Avizo (registered trademark, manufactured by FEI., Inc.) to calculate the number of domains N, the arithmetic mean of the spherical equivalent diameters of the domains Da, and the proportion V of the total volume of the domains in the first-shaped body.

[0202] [Evaluation 3: Measurement of parameters indicating viscoelasticity]

[0203] First, a cubic first-formed body with a side measurement of 100 μm was obtained as described in Evaluation 1. Sections were prepared from the first-formed body using a slicer. Then, viscoelastic images were measured using a scanning probe microscope (product name: S-Image, manufactured by SIINanotechnology, Inc.). The measurement mode for the viscoelastic images was VE-DFM. The cantilever used was "SI-DF3" (product name, manufactured by Hitachi High-Tech Science Corporation, spring constant = 1.9 N / m). The scanning frequency was 0.5 Hz.

[0204] The parameters indicating the viscoelastic term were calculated for each observation region from the obtained viscoelastic images, with 10 points for the matrix and 10 points for the domain. Their arithmetic mean was used to determine the parameter A (mV) indicating the viscoelastic term of the domain and the parameter B (mV) indicating the viscoelastic term of the matrix.

[0205] [Evaluation 4: Measurement of Micro-rubber Hardness]

[0206] First, use scissors to cut a 2mm thick sheet of polyurethane elastomer molded body to obtain a cubic second molded body with one side measuring 2mm.

[0207] The micro rubber hardness of the second molded body was measured using a micro rubber hardness tester (product name: MD-1capa, manufactured by Kobunshi Keiki Co., Ltd.). The second molded body was left to stand at 23°C for at least 24 hours, and the measurement was performed using a measuring device placed in the same environment. A type A indenter (0.50 mm height, 0.16 mm diameter, cylindrical, 4 mm outer diameter, 1.5 mm inner diameter) was used, and the measurement mode was peak hold mode.

[0208] [Evaluation 5: Measurement of deformation resilience]

[0209] First, use scissors to cut a 2mm thick sheet of polyurethane elastomer molded body to obtain a cubic second molded body with one side measuring 2mm.

[0210] The measurement point was approximately set at the center of a freely chosen surface of the second molded body, and an indentation test was performed using a nano-indenter (product name: Fischerscope HM2000, manufactured by Fischer Instruments, a four-corner pyramid Vickers indenter with a 136° relative angle) at 23°C. The Vickers indenter was pressed into the second molded body at a load rate of 10 mN / 30 seconds and the 10 mN load was maintained for 60 seconds. The load was then released at 10 mN / 30 seconds, and the strain was measured 5 seconds after load release to measure the recovery from deformation.

[0211] [Evaluation 6: Measurement of Solvent Extraction Rate C]

[0212] First, a 2mm thick sheet of polyurethane elastomer was prepared using a mold for preparing 2mm thick sheets. The sheet was then cut into slices 25mm long, 10mm wide, and 2mm thick to obtain a third molded body. According to Japanese Industrial Standard (JIS) K6229:2015, the third molded body was subjected to Soxhlet extraction at 80°C for 4 hours using acetone as the extraction solvent. The ratio of the mass of the resulting extract E1 to the mass of the third molded body was calculated as the solvent extraction rate C (mass %).

[0213] [Evaluation 7: Measurement of Solvent Extraction Rate D of Powder]

[0214] First, the 2mm thick sheet of polyurethane elastomer was cut into slices 25mm long, 10mm wide, and 2mm thick using scissors to obtain a third molded body. The third molded body was sandwiched between two pieces of Kiriyama funnel filter paper 5B, and then sandwiched between two pieces of degreased aluminum sheets. The product was pulverized for 1 minute at 10MPa using a 50-ton press (product name: PEF 5041, manufactured by KansaiRoll Co., Ltd.) preheated to 130°C.

[0215] To determine the size of the powder, the particle size distribution was measured using a laser diffraction / scattering particle size distribution analyzer (product name: Partica LA-960V2, manufactured by Horiba, Ltd.) equipped with a drying measurement unit, and the particle size (mode diameter) showing the maximum peak was determined.

[0216] Furthermore, two pieces of Kiriyama funnel filter paper containing the pulverized third-shaped body were folded and placed inside a Soxhlet cylindrical filter paper. Extract E2 was obtained in the same manner as the solvent extraction rate C described above, and the solvent extraction rate D (mass %) of the powder was determined.

[0217] [Evaluation 8: Measurement of the number-average molecular weight of extract E2]

[0218] Extract E2 obtained by solvent extraction of powder was collected, dissolved in THF, and measured using the following measuring apparatus and conditions.

[0219] Measuring device: HLC-8320GPC (product name, manufactured by Tosoh Corporation)

[0220] Pillar: TSKgel SuperMultipore HZ-N (product name, manufactured by Tosoh Corporation) × 2

[0221] Solvent: THF

[0222] Temperature: 40℃

[0223] Flow rate: 0.35 mL / min

[0224] Measurements were performed using an RI (refractive index) detector. Furthermore, calibration curves were created using the following materials as standard samples: TSK standard polystyrene (product names: “A-1000,” “A-2500,” “A-5000,” “F-1,” “F-2,” “F-4,” “F-10,” “F-20,” “F-40,” “F-80,” and “F-128,” manufactured by Tosoh Corporation). Based on this calibration curve, the number-average molecular weight of extract E2 was calculated from the retention times of the obtained measurement samples.

[0225] [Evaluation 9: Viscosity measurement of extract E2]

[0226] A total of 10 μL of extract E2 was collected from the measurement of solvent extraction rate D of the powder. The viscosity of the collected extract E2 was then measured using an ultramicro sample viscometer (product name: m-VROC, manufactured by RheoSense, Inc.) at a temperature of 25 °C and a shear rate of 1 (1 / s), and the result was taken as the viscosity of extract E2.

[0227] [Evaluation 10: Measurement of Abrasion Resistance]

[0228] According to JIS R1613:2010, abrasion resistance was determined under the following conditions (1) to (6) on the surface of a sheet-like abrasion specimen made of polyurethane elastomer and measured to be 30 mm in length, 30 mm in width and 2 mm in thickness, using a ball-disc abrasion tester (product name: HEIDON Type:20, manufactured by Shinto Chemical Co., Ltd.).

[0229] (1) Ball

[0230] Material: Stainless steel

[0231] Diameter: 10mm

[0232] (2) Load: 100g

[0233] (3) Environment: Temperature 23℃, 50%RH

[0234] (4) Time: 60 minutes

[0235] (5) Sliding circle diameter: 10mm

[0236] (6) Rotation speed of the disc on which the sample is placed: 300 rpm.

[0237] The abrasion test was conducted as follows: First, the mass of the abrasion specimen was measured. Next, the abrasion specimen was fixed with double-sided tape, so that the center of the abrasion specimen was approximately positioned at the center of the sliding disc of the ball-disc abrasion tester (product name: HEIDON Type: 20, manufactured by Shinto Chemical Co., Ltd.). At this time, the surface of the abrasion specimen in the thickness direction was placed in contact with the sliding disc. Next, the indenter composed of the aforementioned balls was pressed onto the center of the abrasion specimen with a load of 100g, and the abrasion specimen was rotated and slid at a sliding circle diameter of 10mm and a rotation speed of 300rpm for 60 minutes. After 60 minutes, the test was stopped, the abrasion debris and double-sided tape were removed, and the mass of the specimen was measured. The mass loss rate (mass%) was calculated from the mass of the specimen before and after the abrasion test.

[0238] [Example 1]

[0239] <Example of preparation of urethane prepolymer UP1>

[0240] A total of 21.5 parts by mass of polyol A-1, as a polyether polyol (first polyol) having at least two hydroxyl groups and a second structure represented by formula (2), 0.4 parts by mass of polyisocyanate B-1, as a first polyisocyanate, and 500 ppm of curing catalyst C-1 were mixed and heated at 100 °C for 24 hours to synthesize a polyol (first polyether) having at least two isocyanate groups. This was then mixed with 50.2 parts by mass of polyol A-4, as a third polyol (first polycarbonate polyol), and heated at 100 °C for 4 hours to produce a urethane prepolymer (urethane reactive emulsifier) ​​UP1 (step (i)).

[0241] <Preparation Example of Carbamate Elastomer Molded Body No. 1>

[0242] A total of 72.1 parts by weight of urethane prepolymer UP1, 2.2 parts by weight of B-1 as a second polyisocyanate, and 3.8 parts by weight of B-2 as a third polyisocyanate were mixed and stirred at 1600 rpm for 2 minutes using a planetary vacuum stirrer / defoam mixer (product name: V-mini 300, manufactured by EME Inc.) to achieve a homogeneous state (steps (ii) and (iii)). This produced a polyurethane elastomer forming mixture for this embodiment. The polyurethane elastomer forming mixture was then preheated to 130°C and poured into a mold to prepare a 2 mm thick sheet. The mold was thinly coated with a mold release agent. It was then heated to 130°C for 2 hours to induce curing (step (iii)). The cured product was then removed from the mold and post-cured at 80°C for two days to obtain a 2 mm thick sheet polyurethane elastomer molded body No. 1.

[0243] [Example 2]

[0244] <Example of preparation of urethane prepolymer UP2>

[0245] A total of 15.0 parts by mass of polyol A-1 as the first polyol, 6.4 parts by mass of polyol A-7 as the second polyol, 0.5 parts by mass of polyisocyanate B-1 as the first polyisocyanate, and 500 ppm of curing catalyst C-1 were uniformly mixed and heated at 100°C for 24 hours to synthesize a polyol (first polyether) with terminal isocyanate groups. This was then mixed with 50.2 parts by mass of polyol A-4 as the third polyol (first polycarbonate polyol) and heated at 100°C for 4 hours to produce urethane prepolymer (urethane reactive emulsifier) ​​UP2 (step (i)).

[0246] <Preparation Example of Carbamate Elastomer Molded Body No. 2>

[0247] Except for using 72.1 parts by weight of urethane prepolymer UP2, 2.1 parts by weight of B-1 as the second polyisocyanate, and 3.8 parts by weight of B-2 as the third polyisocyanate, polyurethane elastomer molded body No. 2 was obtained in the same manner as in Example 1.

[0248] [Examples 3 and 4]

[0249] Polyurethane elastomer molded parts No. 3 and No. 4 were prepared in the same manner as in Example 2, except that the materials shown in Table 2 were used in the blending amounts shown in Table 2.

[0250] [Examples 5 to 9 and Comparative Examples 1 and 2]

[0251] Except for using the materials shown in Table 2 in the blending amounts shown in Table 2, polyurethane elastomer molded bodies No. 5 to No. 9 and polyurethane elastomer molded bodies No. C1 and No. C2 were prepared in the same manner as in Example 1.

[0252] [Comparative Example 3]

[0253] <Example of Preparation of Carbamate Elastomer Molded Body No. C3>

[0254] A total of 87.8 parts by weight of polyol A-5 as the first polyol, 4.9 parts by weight of B-1 as the first polyisocyanate, 7.3 parts by weight of B-2 as the second polyisocyanate, and 500 ppm of curing catalyst C-1 were mixed and stirred at 1600 rpm for 2 minutes using a planetary vacuum stirrer / defoamer to achieve a homogeneous state, thereby producing a polyurethane elastomer forming mixture. Next, except that the polyurethane elastomer forming mixture was used, a polyurethane elastomer molded article No. C3 was obtained in the same manner as in Example 1.

[0255] [Comparative Example 4]

[0256] <Example of Preparation of Carbamate Elastomer Molded Body No. C4>

[0257] A total of 23.5 parts by weight of polyol A-2 as the first polyol, 43.6 parts by weight of polyol A-6 as the second polyol, 3.8 parts by weight of B-1 as the first polyisocyanate, 5.7 parts by weight of B-2 as the second polyisocyanate, and 500 ppm of curing catalyst C-1 were mixed and stirred at 1600 rpm for 2 minutes using a planetary vacuum stirrer / defoamer to achieve a homogeneous state, thereby producing a polyurethane elastomer forming mixture. Then, except for using this polyurethane elastomer forming mixture, polyurethane elastomer molded article No. C4 was obtained in the same manner as in Example 1.

[0258] [Table 2]

[0259]

[0260] [Table 3]

[0261]

[0262] The evaluation results of the polyurethane elastomers of Examples 1 to 9 and Comparative Examples 1 to 4 are shown in Table 4.

[0263] [Table 4]

[0264]

[0265] In this table, PPG represents a structure derived from polypropylene glycol, PTMG represents a structure derived from polytetramethylene glycol, PC represents a structure derived from polycarbonate urethane, PE represents a structure derived from polyester urethane, and F3 represents an addition polymer of glycerol and at least one selected from the group consisting of ethylene oxide and propylene oxide.

[0266] Compared to the polyurethane elastomer molded body No. C1 obtained in Comparative Example 1, which differed only in the catalyst used, the polyurethane elastomer molded body No. 1 of Example 1 exhibited a significantly lower solvent extraction rate D of the pulverized material. Furthermore, the polyurethane elastomer molded body No. C2 obtained in Comparative Example 2, which used a larger amount of catalyst than in Comparative Example 1, exhibited an improved solvent extraction rate D of the pulverized material, but showed increased micro-rubber hardness. The polyurethane elastomer molded bodies No. C3 and No. C4, which lacked domain structures and were obtained in Comparative Examples 3 and 4, exhibited D / C ratios close to 1, but showed significantly reduced abrasion resistance compared to Example 1 and the other examples.

[0267] Furthermore, the polyurethane elastomer molded body No. 2 of Example 2 and the polyurethane elastomer molded body No. 3 of Example 3 further comprise, within their domains, an addition polymer structure consisting of glycerol and at least one selected from the group consisting of ethylene oxide and propylene oxide. Therefore, the glycerol-derived triple-branched structure increases the number of urethane bonds at the boundary portion between the matrix and the domain, thereby further suppressing the exudation of domain-derived components to the surface of the polyurethane elastomer molded body. The polyurethane elastomer molded body No. 4 of Example 4 uses the same curing catalyst as in Comparative Example 1, but further comprises, within its domains, an addition polymer structure consisting of glycerol and at least one selected from the group consisting of ethylene oxide and propylene oxide. This makes the solvent extraction rate D of the powder equivalent to that of Example 1.

[0268] This disclosure is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the appended claims are attached to clarify the scope of this disclosure.

[0269] This application claims priority based on Japanese Patent Application No. 2023-138464, filed on August 28, 2023, and Japanese Patent Application No. 2024-134221, filed on August 9, 2024, the entire contents of which are incorporated herein by reference.

[0270] Explanation of reference numerals in the attached figures

[0271] 3: Polyurethane molded body, 31: Matrix, 32: Domain

Claims

1. A polyurethane elastomer having a matrix and a plurality of domains dispersed within the matrix, wherein, in a first molded body having a cubic shape measuring 100 pm on a side and composed of the polyurethane elastomer, the number N of the domains contained is 10 to 77,000; the arithmetic mean Da of the sphere-equivalent diameters of the domains is 1.0 to 30.0 pm; the proportion V of the total volume of the domains in the first molded body is 15 to 45% by volume; in a cross section parallel to one surface of the first molded body, the relationship between a parameter A indicative of the viscoelastic term of the domains and a parameter B indicative of the viscoelastic term of the matrix is A < B as measured in a viscoelastic image taken with a scanning probe microscope; a second molded body composed of the polyurethane elastomer has a micro-rubber hardness at a temperature of 23°C of 20 to 50 degrees, in an indentation test of the second molded body using a nanoindenter at a temperature of 23°C, when a Vickers indenter is pressed into the second molded body at a load speed of 10 mN / 30 seconds, a load of 10 mN is maintained for 60 seconds, and then the load is released, the strain after 5 seconds from the release of the load is 1.0 pm or less; when a third molded body composed of the polyurethane elastomer is subjected to a Soxhlet extraction for an extraction time of 4 hours at an extraction temperature of 80°C by using acetone as an extraction solvent in accordance with Japanese Industrial Standard (JIS) K6229:2015, and the ratio of the mass of the obtained extract E1 to the mass of the third molded body is taken as C (mass %), and when a powder having a mode diameter of less than 1 pm of the third molded body is subjected to a Soxhlet extraction for an extraction time of 4 hours at an extraction temperature of 80°C by using acetone as an extraction solvent in accordance with Japanese Industrial Standard (JIS) K6229:2015, and the ratio of the mass of the obtained extract E2 to the mass of the powder is taken as D (mass %), D / C is 1.0 to 5.

0.

2. The polyurethane elastomer according to claim 1, wherein the number average molecular weight of the extract E2 is 2,000 to 100,000.

3. The polyurethane elastomer according to claim 1 or 2, wherein the viscosity of the extract E2 is 10,000 mPa-s or less.

4. The polyurethane elastomer according to any one of claims 1 to 3, wherein, the polyurethane elastomer has a first structure represented by the following formula (1) and a second structure represented by the following formula (2), the matrix contains the first structure and the domains contain the second structure: In formula (1), R 1 represents an alkylene group having 3 to 12 carbon atoms; In formula (2), R 2 represents an alkylene group having 3 to 6 carbon atoms.

5. The polyurethane elastomer according to claim 4, wherein, the domains have a third structure, and the third structure is an addition polymer of glycerol and at least one selected from the group consisting of oxirane and oxetane.

6. The polyurethane elastomer according to any one of claims 1 to 5, wherein, When a ball-on-disc abrasion test in conformity with JIS R1613:2010 is performed under the following conditions (1) to (6) on a surface in the thickness direction of a sheet-like abrasion test sample composed of the polyurethane elastomer and measuring 30 mm in length, 30 mm in width, and 2 mm in thickness, the mass loss rate of the abrasion test sample is 10.0% by mass or less: (1) Ball Material: stainless steel Diameter: 10 mm (2) Load: 100 g (3) Environment: temperature 23°C, 50% RH (4) Time: 60 minutes (5) Sliding circle diameter: 10 mm (6) Rotational speed of the disc on which the abrasion test sample is placed: 300 rpm.

7. A polyurethane molded body comprising the polyurethane elastomer according to any one of claims 1 to 6.

8. The polyurethane molded body according to claim 7, wherein the polyurethane molded body has a foamed structure.

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