Thermoplastic polyurethane

Abstract

A thermoplastic polyurethane including a structural unit (A) derived from a polymeric polyol (a) having a hydroxyl group at an end thereof, a structural unit (B) derived from a polyisocyanate (b), and a structural unit (C) derived from a chain extender (c), wherein: the polymeric polyol (a) includes structural units derived from a branched polyol (a1) and a C7-11 polycarboxylic acid (a2), and has a number-average molecular weight of 500 or greater; and 50-90 mass% of the structural unit (A), 8-45 mass% of the structural unit (B), and 2-10 mass% of the structural unit (C) are included in 100 mass% of all the structural units in the thermoplastic polyurethane.

Description

Thermoplastic polyurethane

[0001] The present invention relates to thermoplastic polyurethanes.

[0002] Thermoplastic polyurethane (TPU) is suitable for extrusion-molded and injection-molded products such as film products. For example, low-hardness TPU is used in medical tubing, shoe cushioning materials, and protective films for resins and metals. TPU is generally produced by condensation polymerization of polyol, isocyanate, and chain extender. It is said that the polyol unit is the main component of the soft segment. Furthermore, because chain extenders are typically more reactive with isocyanates than polyols, it is said that the unit consisting of isocyanate and chain extender is the main component of the hard segment.

[0003] For example, Patent Document 1 discloses a plasticizer-free low-hardness thermoplastic polyurethane resin composition containing: a) 70 to 80% by weight of a polyol including poly(3-methylpentylene adipate) glycol; b) 13 to 20% by weight of a diisocyanate; c) 2 to 6% by weight of a chain extender; and d) 0.001 to 0.1% by weight of a catalyst. Patent Document 2 discloses a polyurethane elastomer containing 70 to 80% hydrophobic polyester polyol, 5 to 8% chain extender, and 15 to 25% diphenylmethane diisocyanate, and having a Shore hardness of 55 to 75A, wherein the hydrophobic polyester polyol is formed by polymerizing a long-chain dibasic acid and a diol and has a molecular weight of 2000 to 6000 g / mol; the molar ratio of the long-chain dibasic acid to the diol is 1:1.05 to 1.25; the diol is a side-chain diol or a combination of a side-chain diol and a linear diol; and the molar ratio of the linear diol in the combination of the side-chain diol and the linear diol is 0 to 20%.

[0004] Korean Patent Publication No. 10-2006-0092516 Chinese Patent Publication No. 112142960

[0005] For example, when TPU is used in applications such as automotive parts or industrial parts, it may be used in high-temperature environments, and properties such as strength and rubber elasticity must be maintained even in high-temperature environments. Furthermore, when TPU is used in low-temperature environments, such as in applications such as transport belts for handling food at low temperatures, or in cold regions, it is necessary for TPU to maintain low-temperature properties such as hardness and flexibility. To enable use in such environments, TPUs have recently been required to possess both better heat resistance and excellent low-temperature properties. However, as a result of studies by the present inventors, it was found that the low-hardness thermoplastic polyurethane resin composition described in Patent Document 1 exhibits good low-temperature properties but is unable to exhibit sufficient heat resistance. Furthermore, as a result of studies by the present inventors, it was found that the polyurethane elastomer described in Patent Document 2 exhibits good heat resistance but insufficient low-temperature properties. Therefore, an object of the present invention is to provide a thermoplastic polyurethane that can exhibit both good heat resistance and excellent low-temperature properties.

[0006] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by producing a thermoplastic polyurethane that satisfies certain requirements. That is, the present invention encompasses the following inventions: [1] A thermoplastic polyurethane containing structural units (A) derived from a polymer polyol (a) having a terminal hydroxyl group, structural units (B) derived from a polyisocyanate (b), and structural units (C) derived from a chain extender (c), wherein the polymer polyol (a) contains structural units derived from a branched polyol (a1) and a polycarboxylic acid (a2) having 7 to 11 carbon atoms, and has a number average molecular weight of 500 or more, and wherein, relative to 100% by mass of all structural units in the thermoplastic polyurethane, the structural units (A) account for 50 to 90% by mass, the structural units (B) for 8 to 45% by mass, and the structural units (C) for 2 to 10% by mass. [2] The thermoplastic polyurethane according to [1], which contains 60 to 90 mass% of structural units (A), 8 to 38 mass% of structural units (B), and 2 to 8 mass% of structural units (C), based on 100 mass% of all structural units in the thermoplastic polyurethane. [3] The thermoplastic polyurethane according to [1] or [2], wherein the branched polyol (a1) is 3-methyl-1,5-pentanediol. [4] The thermoplastic polyurethane according to any one of [1] to [3], wherein the chain extender (c) is a diol having a molecular weight of less than 500. [5] The thermoplastic polyurethane according to any one of [1] to [4], which has a durometer A hardness of HDA 95 or less, measured in accordance with JIS K 7215-1986. [6] The thermoplastic polyurethane according to any one of [1] to [5], having a durometer A hardness of HDA 80 or less as measured in accordance with JIS K 7215-1986. [7] The thermoplastic polyurethane according to any one of [1] to [6], having a crystallization temperature of -15°C or less, or having no crystallization temperature. [8] The complex modulus E at 25°C of a sheet produced by injection molding ＊ Complex modulus E at 150 ° C. ＊ The ratio of [E ＊ (150°C) / E ＊[9] A method for producing a thermoplastic polyurethane, comprising reacting, with respect to 100% by mass of the total amount of raw material components of the thermoplastic polyurethane, at least 50 to 90% by mass of a polymer polyol (a) having a hydroxyl group at a terminal, 8 to 45% by mass of a polyisocyanate (b), and 2 to 10% by mass of a chain extender (c), wherein the polymer polyol (a) contains structural units derived from a branched polyol (a1) and a polycarboxylic acid (a2) having 7 to 11 carbon atoms, and is a polyol having a number average molecular weight of 500 or more.

[10] A method for producing a thermoplastic polyurethane according to [9] above, wherein a thermoplastic polyurethane is obtained by reacting at least 60 to 90 mass% of a high molecular weight polyol (a) having a hydroxyl group at its terminal, 8 to 38 mass% of a polyisocyanate (b), and 2 to 8 mass% of a chain extender (c), relative to 100 mass% of the total amount of raw materials for the thermoplastic polyurethane.

[11] A method for producing a thermoplastic polyurethane according to [9] or

[10] above, wherein a catalyst (d) is used in an amount of 0.1 to 1,000 ppm by mass relative to the total amount of the high molecular weight polyol (a), the polyisocyanate (b), and the chain extender (c).

[12] A thermoplastic polyurethane composition comprising the thermoplastic polyurethane according to any one of [1] to [8] above.

[13] A molded article comprising the thermoplastic polyurethane according to any one of [1] to [8] above.

[0007] According to the present invention, it is possible to provide a thermoplastic polyurethane that can achieve both good heat resistance and excellent low-temperature properties.

[0008] The following describes examples of embodiments of the present invention (hereinafter also referred to as "one aspect of the present invention"). However, each embodiment described below is merely an example for embodying the technical concept of the present invention, and the present invention is not limited to the following description. The present invention also includes embodiments in which any of the descriptions herein are arbitrarily selected or arbitrarily combined. Although preferred embodiments are described herein, combinations of two or more of the individual preferred embodiments are also preferred. Preferred specifications can be selected arbitrarily; for example, combinations of preferred specifications can be considered more preferable. Unless otherwise specified, the expression "XX to YY" as a numerical range means "XX or more and YY or less" (XX represents the lower limit and YY represents the upper limit). For example, simply describing a numerical range as "10 to 90" means a range of 10 or more and 90 or less. In this specification, for numerical ranges (such as the content of each component, the content of each structural unit, values ​​calculated therefrom, and each physical property), the lower and upper limits described in stages can be independently combined. For example, from a description of "preferably 10 to 90, more preferably 30 to 60" for the same item, the "preferable lower limit (10)" and the "more preferable upper limit (60)" can be combined to form "10 to 60." Furthermore, for a numerical range, for example, based on the description of "preferably 10 to 90, more preferably 30 to 60," the upper limit can be specified as "10 or more" or "30 or more" without a particular upper limit. Similarly, the upper limit can be specified as "90 or less" or "60 or less" without a particular lower limit. The same applies when the upper end of the numerical range is "less than" or when the lower limit is "over." Similarly, for example, from a description of "preferably 10 or more, more preferably 30 or more" for the same item and "preferably 90 or less, more preferably 60 or less," the "preferable lower limit (10)" and the "more preferable upper limit (60)" can be combined to form "10 or more and 60 or less." Similarly, the lower limit value alone can be specified as "10 or more" or "30 or more," and similarly, the upper limit value alone can be specified as "90 or less" or "60 or less."The same applies when the expressions "more than or equal to" and "less than" in the above description are written as "more than" and "less than," respectively. That is, for example, based on the expression "preferably more than 10 and less than 90, more preferably 30 or more and 60 or less," the upper and lower limits can be combined to form "more than 10 and 60 or less" or "30 or more and less than 90." Furthermore, in this specification, unless otherwise specified, the expressions "low temperature properties" and "heat resistance" refer to the "low temperature properties" and "heat resistance" of the thermoplastic polyurethane of one embodiment of the present invention, and are properties that are specifically evaluated by the methods described in the Examples, respectively.

[0009] [Thermoplastic polyurethane] A thermoplastic polyurethane according to one embodiment of the present invention is a thermoplastic polyurethane comprising structural units (A) derived from a polymer polyol (a) having a terminal hydroxyl group, structural units (B) derived from a polyisocyanate (b), and structural units (C) derived from a chain extender (c), wherein the polymer polyol (a) comprises structural units derived from a branched polyol (a1) and a polycarboxylic acid (a2) having 7 to 11 carbon atoms and has a number average molecular weight of 500 or greater, and the thermoplastic polyurethane comprises 50 to 90 mass% of structural units (A), 8 to 45 mass% of structural units (B), and 2 to 10 mass% of structural units (C) relative to 100 mass% of all structural units. The polymer polyol (a) preferably contains structural units derived from a branched polyol (a1) and a polycarboxylic acid (a2) having 7 to 11 carbon atoms, has a number average molecular weight of 500 or more, and contains 60 to 90 mass% of structural units (A), 8 to 38 mass% of structural units (B), and 2 to 8 mass% of structural units (C) relative to 100 mass% of all structural units in the thermoplastic polyurethane. The thermoplastic polyurethane will be described below. In the following description, unless otherwise specified, "the TPU" refers to the thermoplastic polyurethane, which is one embodiment of the present invention.

[0010] <Structural Unit (A)> The structural unit (A) is derived from the high molecular weight polyol (a) having a terminal hydroxyl group, and mainly constitutes a soft segment in the TPU.

[0011] (High polymer polyol (a)) The high polymer polyol (a) contains structural units derived from a branched polyol (a1) and a polycarboxylic acid (a2) having 7 to 11 carbon atoms, and has a number average molecular weight of 500 or more. In this specification, the term "high polymer polyol" refers to a polyol having a number average molecular weight of 500 or more.

[0012] A number average molecular weight of 500 or more for the polymer polyol (a) is preferred from the viewpoint of the mechanical properties of the resulting TPU. Furthermore, a number average molecular weight of 10,000 or less for the polymer polyol (a) is preferred from the viewpoint of ease of charging during synthesis of the TPU. For the same reasons, the number average molecular weight (Mn) of the polymer polyol (a) is preferably 500 to 10,000, more preferably 800 to 8,500, even more preferably 1,000 to 7,500, and even more preferably 1,500 to 6,500. The number average molecular weight of the polymer polyol (a) is a value measured by the method described in the Examples.

[0013] From the viewpoints of the viscosity of the polymer polyol (a) and the melt viscosity of the resulting TPU, the number of hydroxyl groups per molecule of the polymer polyol (a) is preferably 2 to 10, more preferably 2 to 5, even more preferably 2 to 4, still more preferably 2 to 3, and still more preferably 2. That is, the polymer polyol (a) is more preferably a polymer diol or a polymer triol, and even more preferably a polymer diol.

[0014] [Branched Polyol (a1)] The high molecular weight polyol (a) has high mobility due to the structural units derived from the branched polyol (a1), which increases the mobility of the soft segments in the TPU. Therefore, for example, even when the proportion of hard segments in the TPU is low, crystallization of the soft segments is unlikely to occur. As a result, the TPU does not crystallize or can have a lower crystallization temperature (Tc), for example, a crystallization temperature (Tc) of −15° C. or lower, resulting in excellent low-temperature properties. Therefore, the TPU can be used suitably even in low-temperature environments.

[0015] The branched polyol (a1) may be any alcohol having a branched structure and two or more hydroxyl groups. From the viewpoint of the viscosity of the resulting polymer polyol (a), the number of hydroxyl groups per molecule of the branched polyol (a1) is preferably 2 to 10, more preferably 2 to 5, even more preferably 2 to 4, still more preferably 2 to 3, and still more preferably 2. That is, the branched polyol (a1) is more preferably a branched diol.

[0016] The branched polyol (a1) is preferably a branched aliphatic diol. As the branched aliphatic diol, for example, a diol having 3 to 11 carbon atoms is preferable, a diol having 4 to 9 carbon atoms is more preferable, a diol having 4 to 7 carbon atoms is even more preferable, and a diol having 5 to 7 carbon atoms is even more preferable. Examples of branched aliphatic diols include 1,2-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-1,4-butanediol, 1,2-pentanediol, 1,3-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 1,4-pentanediol, 2-methyl-1,5-pentanediol, and 3-methyl-1,5-pentanediol. Examples of the hexanediol include 2-ethyl-2,4-pentanediol, 2-ethyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 2-ethyl-1,6-hexanediol, 2-methyl-1,8-octanediol, 2,7-dimethyl-1,8-octanediol, 2-methyl-1,9-nonanediol, 2,8-dimethyl-1,9-nonanediol, and 2-butyl-2-ethyl-1,3-propanediol. These may be used alone or in combination of two or more. The branched aliphatic diol is preferably at least one selected from the group consisting of branched aliphatic diols in which both hydroxyl groups are primary hydroxyl groups, from the viewpoint of high reactivity with polyisocyanate, and more preferably at least one selected from the group consisting of mirror-symmetric branched aliphatic diols, from the viewpoint of providing a homogeneous thermoplastic polyurethane in which both hydroxyl groups have the same reactivity with polyisocyanate.From the viewpoint of availability, the branched aliphatic diol is more preferably at least one selected from the group consisting of 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, and 3-methyl-1,5-pentanediol. From the viewpoint of achieving a low viscosity of the polymer polyol (a), the branched aliphatic diol is even more preferably 3-methyl-1,5-pentanediol.

[0017] Examples of branched aliphatic diols in which both of the two hydroxyl groups are primary hydroxyl groups include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-1,4-butanediol, 2-methyl-1,5-pentanediol, and 3-methyl-1,5-pentanediol. 2-ethyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,6-hexanediol, 2-methyl-1,8-octanediol, 2,7-dimethyl-1,8-octanediol, 2-methyl-1,9-nonanediol, 2,8-dimethyl-1,9-nonanediol, 2-butyl-2-ethyl-1,3-propanediol, etc. These may be used alone or in combination of two or more. Examples of the branched aliphatic diol having mirror symmetry include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, etc. These may be used alone or in combination of two or more.

[0018] The polymer polyol (a) may contain, as a structural unit derived from a polyol component, a structural unit derived from a polyol other than the branched polyol (a1). Examples of the other polyols include linear aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol; alicyclic diols such as cyclohexanedimethanol and cyclohexanediol; and diols obtained by polymerizing a cyclic monomer using the branched polyol (a1) or the other polyol as an initiator, such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or polycaprolactone having a number average molecular weight of 300 to 3,000.

[0019] From the viewpoint of achieving even better low-temperature properties, the content of structural units derived from the branched polyol (a1) in the polymer polyol (a) is preferably 30 to 100 mass%, more preferably 50 to 100 mass%, even more preferably 60 to 100 mass%, still more preferably 75 to 100 mass%, still more preferably 90 to 100 mass%, still more preferably 95 to 100 mass%, and may even be 100 mass%, based on 100 mass% of the total amount of structural units derived from polyols constituting the polymer polyol (a).

[0020] [Polycarboxylic Acid (a2) Having 7 to 11 Carbon Amounts] The polymer polyol (a) contains structural units derived from a polycarboxylic acid (a2) having 7 to 11 carbon atoms. When the polycarboxylic acid (a2) has 7 or more carbon atoms, the soft segments are more hydrophobic than polycarboxylic acids having 6 or fewer carbon atoms, thereby improving phase separation with the highly hydrophilic hard segments. Furthermore, improved phase separation between the soft and hard segments strengthens the cohesive strength of the hard segments, making the complex modulus of the TPU less likely to decrease even at higher temperatures, resulting in superior heat resistance. When the polycarboxylic acid (a2) has 11 or fewer carbon atoms, the mobility of the structural units derived from the polycarboxylic acid in the soft segments is suppressed, thereby suppressing a decrease in the mobility of the soft segments, resulting in superior low-temperature properties for the TPU. The number of carbon atoms in the polycarboxylic acid (a2) is preferably 7 to 10, but may also be 8 to 10, or even 9 or 10.

[0021] The polycarboxylic acid (a2) may be a carboxylic acid or an acid anhydride thereof having 7 to 11 carbon atoms and two or more carboxy groups. From the viewpoint of the viscosity of the resulting polymer polyol (a), the number of carboxy groups per molecule of the polycarboxylic acid (a2) is preferably 2 to 10, more preferably 2 to 5, even more preferably 2 to 4, still more preferably 2 to 3, and even more preferably 2. That is, the polycarboxylic acid (a2) is more preferably a dicarboxylic acid having 7 to 11 carbon atoms. Examples of the dicarboxylic acid having 7 to 11 carbon atoms include aliphatic dicarboxylic acids having 7 to 11 carbon atoms, alicyclic dicarboxylic acids having 7 to 11 carbon atoms, and aromatic dicarboxylic acids having 7 to 11 carbon atoms. The dicarboxylic acid having 7 to 11 carbon atoms is preferably an aliphatic dicarboxylic acid having 7 to 11 carbon atoms. Examples of the aliphatic dicarboxylic acids having 7 to 11 carbon atoms include pimelic acid (7 carbon atoms), suberic acid (8 carbon atoms), azelaic acid (9 carbon atoms), sebacic acid (10 carbon atoms), and undecanedioic acid (11 carbon atoms). Examples of the alicyclic dicarboxylic acids having 7 to 11 carbon atoms include 1,1-cyclohexanedicarboxylic acid (8 carbon atoms), 1,2-cyclohexanedicarboxylic acid (8 carbon atoms), 1,3-cyclohexanedicarboxylic acid (8 carbon atoms), and 1,4-cyclohexanedicarboxylic acid (8 carbon atoms). Examples of the aromatic dicarboxylic acids having 7 to 11 carbon atoms include phthalic acid (8 carbon atoms), isophthalic acid (8 carbon atoms), and terephthalic acid (8 carbon atoms). These polycarboxylic acids (a2) may be used alone or in combination of two or more.

[0022] The polymer polyol (a) may contain, as a polycarboxylic acid component, a structural unit derived from a polycarboxylic acid other than the polycarboxylic acid (a2) having 7 to 11 carbon atoms. Examples of the other polycarboxylic acid include aliphatic dicarboxylic acids having other than 7 to 11 carbon atoms, such as succinic acid, glutaric acid, adipic acid, and dodecanedioic acid; alicyclic dicarboxylic acids having other than 7 to 11 carbon atoms; and aromatic dicarboxylic acids having other than 7 to 11 carbon atoms, such as 2,6-naphthalenedicarboxylic acid.

[0023] In the polymer polyol (a), the content of structural units derived from the polycarboxylic acid (a2) having 7 to 11 carbon atoms is, from the viewpoint of easily achieving both excellent low-temperature properties and heat resistance, preferably 50 to 100 mass%, more preferably 60 to 100 mass%, even more preferably 70 to 100 mass%, still more preferably 80 to 100 mass%, even more preferably 90 to 100 mass%, still more preferably 95 to 100 mass%, and may even be 100 mass%, based on 100 mass% of the total amount of structural units derived from polycarboxylic acids constituting the polymer polyol (a).

[0024] In the polymer polyol (a), the total content of the structural units derived from the branched polyol (a1) and the structural units derived from the polycarboxylic acid (a2) having 7 to 11 carbon atoms is, from the viewpoint of easily achieving both better low-temperature properties and heat resistance, preferably 60 to 100 mass%, more preferably 80 to 100 mass%, even more preferably 85 to 100 mass%, still more preferably 90 to 100 mass%, still more preferably 95 to 100 mass%, and may even be 100 mass%, based on 100 mass% of the total amount of structural units constituting the polymer polyol (a).

[0025] [Method for Producing Polymer Polyol (a)] The method for producing polymer polyol (a) is not particularly limited, and polymer polyol (a) can be produced by a method similar to the polycondensation method of known polyester polyols. For example, polymer polyol (a) can be produced by charging a branched polyol (a1) and a polycarboxylic acid (a2) having 7 to 11 carbon atoms in a predetermined ratio, carrying out an esterification or transesterification reaction, and further polycondensing the resulting reaction product at high temperature under vacuum in the presence of a polycondensation catalyst. Known catalysts can be used as the polycondensation catalyst used in the production of polymer polyol (a), including titanium compounds such as tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium, tetraisopropoxytitanium, and tetrabutoxytitanium; tin compounds such as di-n-butyltin oxide, di-n-butyltin dilaurate, and dibutyltin diacetate; and combinations of acetates of magnesium, calcium, zinc, and the like with antimony oxide or the titanium compounds. The amount of the polycondensation catalyst is preferably 5 to 500 ppm by mass based on the total amount of the branched polyol (a1) and the polycarboxylic acid having 7 to 11 carbon atoms (a2).

[0026] <Structural Unit (B)> The structural unit (B) is derived from the polyisocyanate (b), and in the TPU, the structural unit (B) mainly constitutes a hard segment together with the structural unit (C) described below.

[0027] (Polyisocyanate (b)) As the polyisocyanate (b), polyisocyanates used in the production of ordinary thermoplastic polyurethanes can be used. From the viewpoint of the melt viscosity of the resulting TPU, the number of isocyanate groups per molecule of the polyisocyanate (b) is preferably 2 to 10, more preferably 2 to 5, even more preferably 2 to 4, still more preferably 2 to 3, and still more preferably 2. That is, the polyisocyanate (b) is more preferably a diisocyanate or triisocyanate, and even more preferably a diisocyanate. Furthermore, the diisocyanate is preferably an organic diisocyanate. The organic diisocyanate means at least one selected from the group consisting of aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates.

[0028] Examples of the polyisocyanate (b) include ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dodecamethylene diisocyanate, isophorone diisocyanate, and isopropylidenebis(4-cyclohexylisocyanate). , 1,3-bis(isocyanatomethyl)cyclohexane, cyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexanoate, cyclohexane Aliphatic or alicyclic diisocyanates such as cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, and bis(2-isocyanatoethyl)-4-cyclohexene; 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (abbreviated as MDI), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, and p-phenylene diisocyanate aromatic diisocyanates such as m-xylylene diisocyanate, p-xylylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, chlorophenylene-2,4-diisocyanate, and tetramethylxylylene diisocyanate. These may be used alone or in combination of two or more.Among these, from the viewpoint of availability, the polyisocyanate (b) is preferably at least one selected from the group consisting of hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,5-naphthylene diisocyanate, m-xylylene diisocyanate, and 4,4'-diphenylmethane diisocyanate (MDI). From the viewpoint of good reactivity, the polyisocyanate (b) is more preferably at least one selected from the group consisting of 1,5-naphthylene diisocyanate, m-xylylene diisocyanate, and 4,4'-diphenylmethane diisocyanate (MDI), and even more preferably 4,4'-diphenylmethane diisocyanate (MDI).

[0029] <Structural Unit (C)> The structural unit (C) is derived from the chain extender (c). Although there are no particular limitations, as mentioned above, it is generally believed that a unit consisting of an isocyanate and a chain extender is the main component of a hard segment. Therefore, the structural unit (C) constitutes a hard segment mainly together with the structural unit (B) in the TPU.

[0030] (Chain extender (c)) As the chain extender (c), which is a raw material constituting the structural unit (C), any of the chain extenders conventionally used in the production of ordinary thermoplastic polyurethanes may be used. Specifically, it is preferable to use a low molecular weight compound having two or more active hydrogen atoms in the molecule that can react with isocyanate groups, and it is more preferable to use a compound that has two or more active hydrogen atoms in the molecule that can react with isocyanate groups and has a molecular weight of less than 500. The molecular weight is more preferably 450 or less, and even more preferably 400 or less.

[0031] Examples of the chain extender (c) include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and neopentanediol. diols such as butyl glycol, 1,6-hexanediol, 2,5-dimethyl-2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,4-bis(β-hydroxyethoxy)benzene, 1,4-cyclohexanediol, cyclohexanedimethanol (e.g., 1,4-cyclohexanedimethanol), bis(β-hydroxyethyl)terephthalate, 1,9-nonanediol, m-xylylene glycol, p-xylylene glycol, and triethylene glycol;Ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 3-methylpentamethylenediamine, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,2-diaminopropane, 1,3-diaminopropane propane, hydrazine, xylylenediamine, isophoronediamine, piperazine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, tolylenediamine, xylenediamine, adipic acid dihydrazide, isophthalic acid dihydrazide, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-methylene-bis(2-chloroaniline), 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl sulfide, 2,6-diaminotoluene, 2,4-diaminochlorobenzene, 1,2-diaminoanthraquinone, 1,4-diaminoanthraquinone, 3,3'-diaminobenzophenone, diamines such as 3,4-diaminobenzophenone, 4,4'-diaminobenzophenone, 4,4'-diaminobibenzyl, 2,2'-diamino-1,1'-binaphthalene, 1,3-bis(4-aminophenoxy)alkane, 1,4-bis(4-aminophenoxy)alkane, 1,5-bis(4-aminophenoxy)alkane, etc., 1,n-bis(4-aminophenoxy)alkanes (n is 3 to 10), 1,2-bis[2-(4-aminophenoxy)ethoxy]ethane, 9,9-bis(4-aminophenyl)fluorene, and 4,4'-diaminobenzanilide;These may be used alone or in combination of two or more.

[0032] Among the above, the chain extender (c) is preferably a diol, more preferably a diol having a molecular weight of less than 500. The molecular weight of the diol is more preferably 450 or less, and even more preferably 400 or less. From the viewpoints of availability and reactivity, the diol having a molecular weight of less than 500 is preferably at least one selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, and 3-methyl-1,5-pentanediol, more preferably at least one selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, and 3-methyl-1,5-pentanediol, even more preferably at least one selected from the group consisting of ethylene glycol, 1,3-propanediol, and 1,4-butanediol, and still more preferably at least one selected from the group consisting of ethylene glycol and 1,4-butanediol. Here, the molecular weight of the chain extender (c) refers to a value obtained by summing the atomic weights of the elements constituting the compound. For example, when the chain extender (c) is a diol, the molecular weight can also be calculated as the sum of the atomic weights of the elements constituting the molecular formula representing the diol. The molecular weight of the chain extender (c) can also be measured, for example, using gas chromatography-mass spectrometry (GC-MS).

[0033] <Other Structural Units (U)> The TPU may further contain other structural units (U) in addition to the structural units (A), (B), and (C), as long as the other structural units (U) do not interfere with the objects and effects of the present invention. Examples of the other structural units (U) include structural units derived from polycarbonate, structural units derived from polyether, and structural units derived from polyurea.

[0034] Furthermore, as long as the objectives and effects of the present invention are not impaired, the raw materials constituting the structural units (A), (B), and (C) of the TPU, as well as the other structural unit (U), may be produced from petroleum-derived raw materials or plant-derived raw materials. Alternatively, these raw materials may be produced using raw materials in a mass balance system. For example, 3-methyl-1,5-pentanediol, which is the most preferred branched polyol (a1), can be synthesized by using petroleum-derived isobutene as a starting material, followed by an ene reaction, an oxo reaction, and then a hydrogenation reaction. Furthermore, 3-methyl-1,5-pentanediol can also be synthesized by hydrogenating 3-methyl-2-pentene-1,5-diol, which is obtained by the ene reaction of isobutene, and its isomers. For example, isobutene may be obtained by the dehydration reaction of 2-methyl-1-propanol, which is obtained by fermentation of sugars derived from plants, as well as petroleum. For example, 3-methyl-1,5-pentanediol can be synthesized using mevalonolactone obtained by fermentation of plant-derived sugars as a starting material, and can also be synthesized by subjecting mevalonolactone to a dehydration reaction, an olefin hydrogenation reaction, and a lactone hydrogenation reaction in that order. Also, mevalonolactone can be synthesized by subjecting it to a lactone hydrogenation reaction, a dehydration reaction, and an olefin hydrogenation reaction in that order. Sebacic acid, which is preferred as the polycarboxylic acid (a2), can be synthesized by an alkali fusion method using plant-derived castor oil as a starting material.

[0035] <Content of Each Structural Unit> (Content of Structural Unit (A)) The TPU contains 50 to 90% by mass of the structural unit (A) relative to 100% by mass of all structural units in the TPU. When the content of the structural unit (A) is 50% by mass or more, a TPU having a suitable low hardness range can be synthesized. Furthermore, when the content of the structural unit (A) is 90% by mass or less, a TPU having good mechanical properties can be synthesized. From the same viewpoint, the content of the structural unit (A) relative to 100% by mass of all structural units in the TPU is preferably 60 to 90% by mass, more preferably 65 to 90% by mass, even more preferably 70 to 90% by mass, and still more preferably 75 to 90% by mass.

[0036] (Content of Structural Unit (B)) The TPU contains 8 to 45% by mass of the structural unit (B) relative to 100% by mass of all structural units in the TPU. When the content of the structural unit (B) is 8% by mass or more, the TPU can be synthesized with good mechanical properties. Furthermore, when the content of the structural unit (B) is 45% by mass or less, the TPU can be synthesized with a suitable low hardness range. From the same viewpoint, the content of the structural unit (B) relative to 100% by mass of all structural units in the TPU is preferably 8 to 38% by mass, more preferably 8 to 33% by mass, even more preferably 8 to 28% by mass. From the viewpoint of synthesizing a TPU with good mechanical properties and a lower hardness range, it is still more preferably 8 to 23% by mass.

[0037] (Content of Structural Unit (C)) The TPU contains 2 to 10 mass% of the structural unit (C) relative to 100 mass% of all structural units in the TPU. When the content of the structural unit (C) is 2 mass% or more, the TPU can be synthesized with good mechanical properties. Furthermore, when the content of the structural unit (C) is 8 mass% or less, the TPU can be synthesized with a suitable low hardness range. From the same viewpoint, the content of the structural unit (C) relative to 100 mass% of all structural units in the TPU is preferably 2 to 8 mass%. From the viewpoint of synthesizing a TPU with good mechanical properties and a lower hardness range, the content is more preferably 2 to 6 mass%, even more preferably 2 to 5 mass%, and even more preferably 3 to 4 mass%.

[0038] (Total Content of Structural Units (A), (B), and (C)) The total content of structural units (A), (B), and (C) in the TPU (100% by mass) is 70 to 100% by mass, preferably 75 to 100% by mass, more preferably 80 to 100% by mass, even more preferably 86 to 100% by mass, still more preferably 90 to 100% by mass, still more preferably 95 to 100% by mass, and may even be 100% by mass. Here, the contents of the structural units (A), (B), and (C) described above can each independently assume the respective contents described above, but it should be understood that when the selected contents are combined, no combination is included in which the total content of structural units (A), (B), and (C) exceeds 100% by mass. In other words, the respective contents of the structural unit (A), the structural unit (B), and the structural unit (C) are a combination in which the total content of the structural unit (A), the structural unit (B), and the structural unit (C) does not exceed 100 mass%.

[0039] In this specification, the content of each structural unit in the TPU can be calculated from the blending amount of raw material compounds forming each structural unit. １ It can also be determined by H-NMR measurement. In this case, if necessary, １３ After identifying each structural unit that constitutes TPU using C-NMR and GC-MS, the content of each structural unit is １ It can also be determined by H-NMR measurement.

[0040] <Method for Producing Thermoplastic Polyurethane> Examples of methods for producing thermoplastic polyurethane include a method for producing a thermoplastic polyurethane by reacting at least 50 to 90 mass% of a polymer polyol (a) having a terminal hydroxyl group, 8 to 45 mass% of a polyisocyanate (b), and 2 to 10 mass% of a chain extender (c) relative to the total 100 mass% of the raw materials for the thermoplastic polyurethane, wherein the polymer polyol (a) contains structural units derived from a branched polyol (a1) and a polycarboxylic acid (a2) having 7 to 11 carbon atoms and is a polyol having a number average molecular weight of 500 or greater. Furthermore, the use of a catalyst (d) is preferred in the method for producing a TPU. The thermoplastic polyurethane obtained by this production method is similar to that described in the section on the thermoplastic polyurethane, which is one aspect of the present invention, and preferred embodiments thereof are also similar.

[0041] The method for producing the TPU is not particularly limited, as long as it can be obtained by blending the aforementioned raw materials in the aforementioned amounts. For example, the TPU can be obtained by polymerization via a urethane reaction using a known prepolymer method or one-shot method. Generally, the prepolymer method is more likely to result in a regular arrangement of the structural unit (C) derived from the chain extender (c) in the molecular chain than the one-shot method, which is believed to improve the dispersibility of the structural unit (C) in the molecular chain. Therefore, it is believed that TPUs obtained by the prepolymer method have better phase separation between soft and hard segments. However, chemical analysis of the dispersibility of the structural unit (C) in the molecular chain is difficult for those skilled in the art. While qualitative analysis of phase separation is possible using small-angle X-ray diffraction, quantitative analysis of the degree of phase separation is difficult. Solution polymerization can also be performed in a solvent inert to the reaction, and melt polymerization can also be performed in the absence of a solvent. More specifically, examples of the melt polymerization include a method of producing the polymer by melt polymerization in which the above-mentioned components are blended in a predetermined ratio in substantially the absence of a solvent and melt-mixed using a single- or multi-screw extruder (continuous melt polymerization method), and a method of producing the polymer by melt polymerization in a batch reactor under weak or no mixing conditions (batch melt polymerization method). Here, solution polymerization is superior to melt polymerization, and batch melt polymerization is superior to continuous melt polymerization in terms of phase separation. This is thought to be because spontaneous separation into soft and hard segments is more likely when the polymer is not affected by kneading during polymerization.

[0042] As one embodiment of the method for producing the TPU, for example, a prepolymer method can be suitably used in which a chain extender (c) is reacted with an isocyanate-terminated prepolymer obtained by previously reacting a high molecular weight polyol (a) with a polyisocyanate (b). In the prepolymer method, it is preferable to use a catalyst (d) when reacting the chain extender (c) with the isocyanate-terminated prepolymer.

[0043] (Catalyst (d)) As the catalyst (d), a urethanization reaction catalyst conventionally used in the production of thermoplastic polyurethanes can be used. Examples of the urethanization reaction catalyst include organotin compounds, organozinc compounds, organobismuth compounds, organotitanium compounds, organozirconium compounds, and amine compounds. Among these, from the viewpoint of reactivity, at least one selected from the group consisting of amine compounds, organotin compounds, and organobismuth compounds is preferred, and from the viewpoint of handleability, amine compounds are more preferred. As the amine compound, tertiary amine compounds are preferred. Examples of tertiary amine compounds include triethylenediamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, bis(2-dimethylaminoethyl)ether, N,N,N',N",N"-pentamethyldiethylenetriamine, N-methylmorpholine, N-ethylmorpholine, N,N-dimethylethanolamine, 1-methylimidazole, 1,2-dimethylimidazole, N,N'-dimethylpiperazine, 1,4-diazabicyclo[2,2,2]octane, 1,8-diazabicyclo[5,4,0]undecene-7, 1,5-diazabicyclo[4,3,0]nonene-5, 1,8-diazabicyclo[5,4,0]decene-7, and 1,4-diazabicyclo[3,3,3]octene-4. These compounds may be used alone or in combination of two or more.

[0044] From the viewpoint of ensuring an appropriate polymerization reaction rate, the amount of the catalyst (d) used is preferably 0.1 to 1,000 ppm by mass, more preferably 1 to 800 ppm by mass, and even more preferably 10 to 500 ppm by mass, relative to the total amount of the high molecular weight polyol (a), the polyisocyanate (b), and the chain extender (c).

[0045] <Various Properties of Thermoplastic Polyurethane> (Durometer A Hardness) From the viewpoint of obtaining better flexibility, the TPU preferably has a durometer A hardness measured in accordance with JIS K 7215-1986 of HDA 95 or less. From the same viewpoint, the durometer A hardness is more preferably 90 or less, even more preferably 80 or less, still more preferably HDA 75 or less, and even more preferably HDA 70 or less. Furthermore, from the viewpoint of ease of molding, the durometer A hardness is preferably HDA 30 or more. From the same viewpoint, the durometer A hardness is more preferably HDA 50 or more, and even more preferably HDA 60 or more. In other words, the durometer A hardness is preferably HDA 30 to 95, more preferably HDA 30 to 90, even more preferably HDA 30 to 80, still more preferably HDA 50 to 75, and even more preferably HDA 60 to 70. Furthermore, as the phase separation of the TPU progresses through the aging process described below, the durometer A hardness increases.

[0046] Here, a known method for reducing the hardness of a thermoplastic polyurethane is to add a plasticizer to a high-hardness thermoplastic polyurethane to produce a low-hardness thermoplastic polyurethane composition. On the other hand, as described below, the TPU according to one embodiment of the present invention can achieve the aforementioned low hardness without substantially containing a plasticizer. That is, the TPU can also be suitably used as a so-called plasticizer-free low-hardness thermoplastic polyurethane. A plasticizer-free low-hardness thermoplastic polyurethane is preferred from the viewpoint of preventing the plasticizer from bleeding out or blooming out from the thermoplastic polyurethane composition.

[0047] (Crystallization Temperature) When the TPU has a crystallization temperature, from the viewpoint of achieving superior low-temperature properties, the crystallization temperature is preferably −15° C. or lower, more preferably −30° C. or lower, and even more preferably −40° C. or lower. There is no particular restriction on the lower limit of the crystallization temperature. Specifically, the crystallization temperature is a value measured by the method described in the Examples. It is also preferable for the TPU to have no observed crystallization temperature when measured by the method described in the Examples. Generally, the crystallization temperature does not change depending on the degree of phase separation.

[0048] (Complex modulus of elasticity E at 25°C ＊ Complex modulus E at 150 ° C. ＊ From the viewpoint of being more excellent in heat resistance, the TPU has a complex modulus of elasticity E at 25°C of a sheet produced by injection molding (a sheet of thermoplastic polyurethane after injection molding). ＊ Complex modulus E at 150 ° C. ＊ The ratio of [E ＊ (150°C) / E ＊ (25°C)] is preferably 0.15 or more, more preferably 0.17 or more, even more preferably 0.18 or more, still more preferably 0.20 or more, still more preferably 0.25 or more, and still more preferably 0.30 or more. ＊ (150°C) / E ＊ (25°C)] is, for example, preferably 1.20 or less, more preferably 1.15 or less, even more preferably 1.10 or less, still more preferably 1.08 or less, still more preferably 1.05 or less, and still more preferably 1.03 or less, from the viewpoint of more excellent heat resistance. ＊ (150°C) / E ＊ (25°C)] is preferably 0.15 to 1.20, more preferably 0.17 to 1.15, even more preferably 0.18 to 1.10, still more preferably 0.20 to 1.08, even more preferably 0.25 to 1.05, and still more preferably 0.30 to 1.03. ＊ (150°C) / E ＊If the ratio [E (25°C)] of the sheet produced by injection molding is within the above range, the difference between the complex modulus at 25°C and that at 150°C is small, and the change in the physical properties of the thermoplastic polyurethane between low-temperature and high-temperature environments is also small. In other words, this indicates that the thermoplastic polyurethane has better heat resistance. ＊ (150°C) / E ＊ (25°C)] is specifically a value measured by the method described in the Examples. ＊ (150°C) / E ＊ (25°C)] becomes a low value. ＊ (150°C) / E ＊ (25°C)] becomes higher.

[0049] Furthermore, the sheet produced by the injection molding can be, for example, one that conforms to item 3.3 of the JIS K 7311-1995 standard. Furthermore, since the sheet used for the evaluation must be a sheet free of molding defects, it is preferable to appropriately set the injection molding conditions so that the resulting sheet does not suffer from molding defects. For example, it is preferable to set the molding conditions so that the TPU can be introduced into the entire surface of the mold and so that molding defects such as shrinkage of the molded product do not occur. In other words, since the evaluation must be performed on a sheet free of molding defects, it is preferable to appropriately set the injection molding conditions depending on the characteristics of the TPU used. Therefore, for example, when comparing by the evaluation, it is desirable to evaluate sheets under injection molding conditions as similar as possible. However, since the first priority is to obtain a sheet free of molding defects (since testing cannot be performed on sheets with molding defects), it may be difficult to necessarily match all molding conditions. Therefore, it is sometimes necessary to obtain a sheet required for evaluation under conditions that are as close as possible to the range and free of molding defects. As mentioned above, it is preferable to appropriately set the injection molding conditions depending on the composition of the TPU used, etc. For example, as one embodiment of the injection conditions, an injection molding machine is used to melt-knead the mixture at a cylinder top temperature of 130 to 280°C, and then injection-molding is performed at an injection pressure of 1 to 200 MPa, a mold retention time of 3 seconds to 10 minutes, and a mold temperature of 0 to 70°C. While appropriately adjusting the conditions within these conditions so that molding defects do not occur, a sheet conforming to item 3.3 of the JIS K 7311-1995 standard can also be obtained.

[0050] In addition, from the viewpoint of being more excellent in heat resistance, the TPU has a complex modulus of elasticity E at 25°C after polymerization and aging and before injection molding. ＊ Complex modulus E at 150 ° C. ＊ The ratio of [E ＊ (150°C) / E ＊ (25°C)] is preferably 0.67 or more, more preferably 0.68 or more, even more preferably 0.70 or more, still more preferably 0.75 or more, still more preferably 0.85 or more, and still more preferably 0.95 or more. ＊(150°C) / E ＊ (25°C)] is, for example, preferably 1.20 or less, more preferably 1.15 or less, even more preferably 1.10 or less, still more preferably 1.08 or less, still more preferably 1.05 or less, and still more preferably 1.03 or less, from the viewpoint of more excellent heat resistance. ＊ (150°C) / E ＊ (25°C)] is preferably 0.67 to 1.20, more preferably 0.68 to 1.15, even more preferably 0.70 to 1.10, still more preferably 0.75 to 1.08, still more preferably 0.85 to 1.05, and still more preferably 0.95 to 1.03. ＊ (150°C) / E ＊ (25°C)] is specifically a value measured by the method described in the Examples.

[0051] (Weight Average Molecular Weight) The weight average molecular weight (Mw) of the TPU is preferably 10,000 to 500,0000, more preferably 20,000 to 250,000, and even more preferably 50,000 to 200,000. A weight average molecular weight (Mw) of 10,000 or more is preferred from the viewpoint of obtaining better mechanical performance and durability, and a weight average molecular weight (Mw) of 500,000 or less is preferred from the viewpoint of obtaining better moldability. The number average molecular weight (Mw) of the TPU can be determined by gel permeation chromatography (GPC) in terms of standard poly(methyl methacrylate). For example, it can be measured by the following method. <GPC measurement conditions> Apparatus: GPC apparatus "HLC-8220" manufactured by Tosoh Corporation Separation column: "TSKgel AWM-M (column diameter = 6.0 mm, column length = 15 cm)" manufactured by Tosoh Corporation (two columns connected in series) Eluent: N,N-dimethylformamide containing 10 mM lithium bromide Eluent flow rate: 1.0 mL / min Column temperature: 40°C Detection method: refractive index (RI) Injection volume: 10 μL Concentration: 1 mg / 1 mL (TPU / N,N-dimethylformamide) Standard: poly(methyl methacrylate)

[0052] [Thermoplastic Polyurethane Composition] One embodiment of the present invention is a thermoplastic polyurethane composition containing the TPU. The TPU may also contain other components as needed. That is, one embodiment of the present invention is a thermoplastic polyurethane composition containing the TPU and other components. The content of the TPU in the thermoplastic polyurethane composition can be adjusted appropriately depending on the application of the thermoplastic polyurethane composition. In one embodiment of the thermoplastic polyurethane composition, the content of the TPU is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on 100% by mass of the thermoplastic polyurethane composition. The upper limit of the TPU content in the thermoplastic polyurethane composition is not particularly limited, but may be, for example, 99.99% by mass.

[0053] Examples of the other components include additives such as plasticizers, crosslinking agents, fillers, crosslinking accelerators, crosslinking aids, softeners, tackifiers, antioxidants, foaming agents, processing aids, adhesion promoters, inorganic fillers, organic fillers, nucleating agents, heat stabilizers, weathering stabilizers, antistatic agents, colorants, lubricants, flame retardants, flame retardant aids (e.g., antimony oxide), blooming inhibitors, release agents, thickeners, antioxidants, conductive agents, and hydrolysis inhibitors (e.g., carbodiimides). Also included are polymers other than the TPU of one embodiment of the present invention. Examples of the polymers other than TPU include TPUs other than the TPU of one embodiment of the present invention, thermosetting polyurethanes, polyvinyl chloride, polymethacrylic acid esters, and thermoplastic polyester elastomers. The total content of the other components in the thermoplastic polyurethane composition is preferably 50% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less. The lower limit of the total content of the other components in the thermoplastic polyurethane composition is not particularly limited, but may be, for example, 0.01% by mass.

[0054] Furthermore, the TPU can achieve low hardness even without a plasticizer. Therefore, from the viewpoint of preventing bleed-out or bloom-out of the plasticizer from the thermoplastic polyurethane composition, it is preferable that the thermoplastic polyurethane composition be substantially free of a plasticizer. Here, "substantially free" specifically means that the plasticizer is present in an amount of 1% by mass or less, preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and even more preferably 0.01% by mass or less, per 100% by mass of the thermoplastic polyurethane composition. Furthermore, the thermoplastic polyurethane composition of one embodiment of the present invention may contain 0% by mass of the plasticizer per 100% by mass of the thermoplastic polyurethane composition. In other words, the plasticizer content in the thermoplastic polyurethane composition of one embodiment of the present invention is 0 to 1% by mass, preferably 0 to 0.1% by mass, more preferably 0 to 0.05% by mass, even more preferably 0 to 0.01% by mass, and may even be 0% by mass.

[0055] The other components can be appropriately blended during or after the polymerization of the TPU, or may be blended in advance with the raw material components (e.g., high molecular weight polyol (a)) before the polymerization of the TPU.

[0056] [Molded Article] A molded article according to one embodiment of the present invention comprises the TPU. Examples of the molded article include automotive parts such as bumpers, side moldings, tail lamp seals, snow chains, ball joint seals, constant velocity joint boots, bellows, spring cover materials, ABS cables, ABS cable plugs, instrument panel skins, gear knobs, console boxes, door seal covers, seating materials, and knobs; industrial parts such as belts, tubes, hoses, wire coating materials, cable coating materials, fire hoses, gears, casters, packing materials, and wind turbines; films and sheets such as various sheets, air mattresses, synthetic leather, and protective films; everyday items such as shoe soles, shoe cushioning materials, watch bands, camera grips, animal ear tags, smartphone cases, tablet cases, keyboard protective covers, and decorative items; medical products such as heart valves, bypass devices, artificial ventricles, dialysis tubes, thin films, connectors, catheters, medical tubes, and pacemaker insulators; construction materials such as interior and exterior materials; and sporting goods such as skis and rackets. Among these, low-hardness thermoplastic polyurethanes are particularly suitable for use in dialysis tubing, catheters, medical tubing, shoe soles, shoe cushioning materials, protective films for resins and metals, etc. Furthermore, because the TPU has excellent heat resistance, it can also be used favorably in applications where it may be used in high-temperature environments, such as automobile parts and industrial parts. Furthermore, because the TPU also has excellent low-temperature properties, it can also be used favorably in applications where it is used in low-temperature environments, such as transport belts for handling food at low temperatures, or in applications where it is used in cold regions.

[0057] The molding method for the molded article is not particularly limited, and various molding methods can be used, such as a molding method in which the TPU or the thermoplastic polyurethane composition is cut or milled immediately after polymerization; a casting or dipping method in which the TPU or the thermoplastic polyurethane composition is dissolved in a solvent to form a homogeneous solution and then formed into a sheet or film; and extrusion molding, injection molding, calendar molding, cast molding, blow molding, inflation molding, foam molding, rotational molding, and slush molding in which the TPU or the thermoplastic polyurethane composition is heated and kneaded and then molded. The molded article may be formed solely from the TPU or the thermoplastic polyurethane composition, or may be a composite molded article of the TPU or the thermoplastic polyurethane composition and other materials (e.g., a laminated structure of the TPU or the thermoplastic polyurethane composition and other materials). The composite molded article may be molded by insert molding, coextrusion molding, or the like, without particular limitation. The TPU, the thermoplastic polyurethane composition, or the molded article immediately after polymerization may be used for various applications as is. For the purpose of improving or stabilizing physical properties by promoting phase separation, the mixture may be used after undergoing an aging process. The time required for the aging process is not particularly limited as long as the purpose can be achieved. For example, from the viewpoint of facilitating the achievement of the purpose, it is preferably 10 minutes or more, more preferably 1 hour or more, even more preferably 2 hours or more, and even more preferably 3 hours or more. Furthermore, from the viewpoint of productivity, it is preferably 3 months or less, more preferably 1 month or less, even more preferably 1 week or less, and even more preferably 1 day or less. In the aging process, the higher the aging temperature, the more easily the purpose can be achieved, so the temperature in the aging process is preferably 30°C or more, more preferably 40°C or more, and even more preferably 50°C or more. Furthermore, from the viewpoint of suppressing thermal deformation of the obtained molded body, the temperature is preferably 150°C or less, more preferably 140°C or less, and even more preferably 130°C or less. The temperature may be changed during the aging process. When the temperature is changed during the aging process, it is preferable to shorten the time of exposure to high temperatures in order to suppress thermal deformation of the obtained molded body.

[0058] The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to these examples.

[0059] The physical properties of the raw materials and thermoplastic polyurethanes in the examples and comparative examples were measured or evaluated by the following methods. (1) Number Average Molecular Weight The number average molecular weight of the polymer polyol (a) used in the examples and comparative examples was determined by the following calculation based on the hydroxyl value of the polymer polyol (a): Number average molecular weight (Mn) of polymer polyol (a) = Molecular weight of KOH (56.1) × Number of functional groups × 1,000 / Hydroxyl value (mg KOH / g) The hydroxyl value was measured by Method B (phthalation method) described in JIS K1557-1:2007.

[0060] (2) Durometer A Hardness (HDA) The durometer A hardness (HDA) of the thermoplastic polyurethane was measured using a type A durometer in accordance with JIS K 7215-1986.

[0061] (3) Low-Temperature Properties (Measurement of Crystallization Temperature (Tc)) The crystallization temperature (Tc) of a thermoplastic polyurethane was measured using differential scanning calorimetry (DSC) under the following measurement conditions, and the peak-top temperature of the exothermic peak observed during the third cooling process described below was taken as the crystallization temperature. The lower the crystallization temperature, the better the low-temperature properties of the thermoplastic polyurethane. Furthermore, even if no crystallization temperature is observed within the measurement temperature range of this example, the thermoplastic polyurethane will still have excellent low-temperature properties. <DSC Measurement Conditions> - Measurement equipment: "DSC 25" manufactured by TA Instruments - Heating rate: +10°C / min - Heating rate: -10°C / min - Nitrogen flow rate: 100 mL / min - Temperature profile (the first to third measurements described below were carried out consecutively in this order): First measurement: Cool from 30°C to -100°C, and hold at -100°C for 5 minutes. Second time: The temperature was increased from -100°C to 200°C and held at 200°C for 5 minutes. Third time: The temperature was decreased from 200°C to -100°C and held at -100°C for 5 minutes.

[0062] (4) Heat resistance The heat resistance of thermoplastic polyurethane is determined by the complex modulus of elasticity E at 25°C. ＊ Complex modulus E at 150 ° C. ＊ The ratio of [E＊ (150°C) / E ＊ The complex modulus of elasticity E at each temperature was calculated. ＊ The above was confirmed by performing DMA (dynamic viscoelasticity) measurements under the following conditions using test pieces (size: width 5 mm x length 15 mm x thickness 2 mm) prepared by punching out each of the thermoplastic polyurethane sheets (two types, one before and one after injection molding) prepared in the examples and comparative examples. <DMA measurement conditions> - Measurement equipment: "DMA 242 E Artemis" manufactured by NETZSCH - Temperature range: heating from -80°C to 150°C - Heating rate: +3°C / min - Frequency: 10 Hz - Deformation mode: tension mode

[0063] The polymer polyols or thermoplastic polyurethanes used in the examples and comparative examples were produced by the following methods: Components (a) to (d) and polyols other than the polymer polyol (a) used were as follows:<High polymer polyols (a)> High polymer polyol 1 (abbreviated as "PO1"): manufactured by Kuraray Co., Ltd., product name "Kuraray Polyol P-4050" (polymer of 3-methyl-1,5-pentanediol and sebacic acid (carbon number: 10), number average molecular weight: 4,000) High polymer polyol 2 (abbreviated as "PO2"): manufactured by Kuraray Co., Ltd., product name "Kuraray Polyol P-6050" (polymer of 3-methyl-1,5-pentanediol and sebacic acid (carbon number: 10), number average molecular weight: 6,000) High polymer polyol 3 (abbreviated as "PO3"): manufactured by Kuraray Co., Ltd., product name "Kuraray Polyol P-2050" (polymer of 3-methyl-1,5-pentanediol and sebacic acid (carbon number: 10), number average molecular weight: 2,000) Polymer polyol 4 (abbreviated as "PO4"): polymer of 1,3-propanediol, 3-methyl-1,5-pentanediol and sebacic acid (carbon number: 10), number average molecular weight: 3,000 Polymer polyol 5 (abbreviated as "PO5"): polymer of 3-methyl-1,5-pentanediol and suberic acid (carbon number: 8), number average molecular weight: 4,000 Polymer polyol 6 (abbreviated as "PO6"): manufactured by Kuraray Co., Ltd., product name "Kuraray Polyol P-3050" (polymer of 3-methyl-1,5 pentanediol and sebacic acid (carbon number: 10), number average molecular weight: 3,000) <Polyols other than polymer polyol (a)> Polymer polyol R1 (abbreviated as "PO-R1"): manufactured by Kuraray Co., Ltd., product name "Kuraray Polyol P-4010" (polymer of 3-methyl-1,5-pentanediol and adipic acid (carbon number 6), number average molecular weight 4,000) Polymer polyol R2 (abbreviated as "PO-R2"): polymer of 3-methyl-1,5-pentanediol and dodecanedioic acid (carbon number 12), number average molecular weight 4,000 Polymer polyol R3 (abbreviated as "PO-R3"): manufactured by Kuraray Co., Ltd., product name "Kuraray Polyol P-2010" (polymer of 3-methyl-1,5-pentanediol and adipic acid (carbon number 6), number average molecular weight 2,000) Polymer polyol R4 (abbreviated as "PO-R4"): manufactured by Daicel Corporation, product name "Placcel (registered trademark) PCL220N" (polycaprolactone diol, number average molecular weight 2,000) Polymer polyol 4, polymer polyol 5 and polymer polyol R2 were produced by the following method.

[0064] Synthesis Example 1 Synthesis of Polymer Polyol 4 1,3-propanediol (100 g), 3-methyl-1,5-pentanediol (156 g), and sebacic acid (256 g) were added to a reaction vessel and heated to 160 ° C. with stirring under nitrogen purging. After confirming that the acid value was 30 mg KOH / g or less, the mixture was cooled to 150 ° C. Thereafter, a 10 wt % toluene solution of tetraisopropyl orthotitanate was added so that the titanium atom (Ti) was 20 ppm by mass relative to the polymer polyol 4 finally obtained in terms of titanium atoms, and the temperature was raised to 180 ° C. After confirming that the target molecular weight was reached from hydroxyl value measurement, approximately 2 wt % of water was added to the polymer polyol 4 finally obtained to deactivate the catalyst, and the mixture was heated at 100 ° C. for 2 hours. Thereafter, the mixture was cooled to 50 ° C., and it was confirmed that the moisture value was 200 ppm by mass or less due to reduced pressure, and the polymer polyol 4 was obtained.

[0065] Synthesis Example 2 Synthesis of Polymer Polyol 5 3-methyl-1,5-pentanediol (286 g) and suberic acid (330 g) were added to a reaction vessel, and the mixture was heated to 160°C with stirring under nitrogen purging. After confirming that the acid value was 30 mgKOH / g or less, the mixture was cooled to 150°C. A 10 wt% toluene solution of tetraisopropyl orthotitanate was then added so that the titanium atom (Ti) was 20 ppm by mass relative to the polymer polyol 5 finally obtained, calculated as titanium atoms, and the mixture was heated to 180°C. After confirming that the target molecular weight had been reached by hydroxyl value measurement, approximately 2 wt% of water was added to the polymer polyol 5 finally obtained to deactivate the catalyst, and the mixture was heated at 100°C for 2 hours. The mixture was then cooled to 50°C, and it was confirmed that the moisture content was 200 ppm by mass or less due to reduced pressure, to obtain the polymer polyol 5.

[0066] Synthesis Example 3: Synthesis of Polymer Polyol R2 3-methyl-1,5-pentanediol (238 g) and dodecanedioic acid (358 g) were added to a reaction vessel, and the mixture was heated to 160 ° C. while stirring under nitrogen purging. After confirming that the acid value was 30 mg KOH / g or less, the mixture was cooled to 150 ° C. Thereafter, a 10 wt% toluene solution of tetraisopropyl orthotitanate was added so that the titanium atom (Ti) was 20 ppm by mass relative to the polymer polyol R2 finally obtained in terms of titanium atoms, and the temperature was raised to 180 ° C. After confirming that the target molecular weight was reached from hydroxyl value measurement, approximately 2 wt% of water was added to the polymer polyol R2 finally obtained to deactivate the catalyst, and the mixture was heated at 100 ° C. for 2 hours. Thereafter, the mixture was cooled to 50 ° C., and it was confirmed that the moisture value was 200 ppm by mass or less due to reduced pressure, and the polymer polyol R2 was obtained.

[0067] <Polyisocyanate (b)> 4,4'-diphenylmethane diisocyanate (manufactured by Tosoh Corporation)

[0068] <Chain extender (c)> 1,4-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) Ethylene glycol (manufactured by Kanto Chemical Co., Ltd.)

[0069] <Catalyst (d)> 1,4-diazabicyclo[2.2.2]octane (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0070] Example 1 Polymer polyol 1 (795 g, 0.20 mol) was placed in a reaction vessel and heated to 80°C. While stirring, 4,4'-diphenylmethane diisocyanate (174 g, 0.70 mol) was added, and the mixture was heated to 100°C and reacted for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2.2.2]octane (0.159 g) and ethylene glycol (31 g, 0.50 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The resulting reaction product was cured at 80°C for 2 hours to form a sheet. Note that the term "curing" refers to the reaction product becoming increasingly polymerized after casting, losing fluidity, and becoming hard. This term is used in a different sense from the curing that occurs, for example, due to a crosslinking reaction using a crosslinking agent in a thermosetting resin. This also applies to the following explanations in this specification. The resulting sheet-like material was aged by storing it under conditions of 125°C for 1 hour and 100°C for 12 hours, in that order, to obtain a thermoplastic polyurethane sheet before injection molding. The resulting thermoplastic polyurethane sheet was then cut into strips. The strip-shaped sheet was melt-kneaded using an injection molding machine "SE130EV" (manufactured by SUMITOMO Heavy Industries, Ltd.) under conditions of a cylinder top temperature of 200°C, an injection pressure of 50 MPa, a mold retention time of 10 seconds, and a mold temperature of 30°C, to obtain a sheet conforming to item 3.3 of the JIS K 7311-1995 standard (wherein the sheet size was 100 mm length x 100 mm width x 2 mm thickness). This sheet was aged for 6 hours at 80°C to obtain a thermoplastic polyurethane sheet after injection molding.

[0071] Example 2 Polymer polyol 1 (784 g, 0.20 mol) was placed in a reaction vessel and heated to 80°C. With stirring, 4,4'-diphenylmethane diisocyanate (172 g, 0.69 mol) was added, and the mixture was allowed to react at 100°C for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2.2.2]octane (0.0784 g) and 1,4-butanediol (44 g, 0.49 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The resulting reaction product was cured at 80°C for 2 hours to form a sheet. The resulting sheet was aged by storing it at 125°C for 1 hour and then at 100°C for 12 hours, yielding a pre-injection-molded thermoplastic polyurethane sheet. The resulting pre-injection-molded thermoplastic polyurethane sheet was then subjected to the same procedures as in Example 1 to obtain a post-injection-molded thermoplastic polyurethane sheet.

[0072] Example 3 Polymer polyol 2 (853 g, 0.14 mol) was placed in a reaction vessel and heated to 80°C. While stirring, 4,4'-diphenylmethane diisocyanate (125 g, 0.50 mol) was added and the mixture was allowed to react at 100°C for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2.2.2]octane (0.170 g) and ethylene glycol (22 g, 0.35 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The reaction product was cured at 80°C for 2 hours to form a sheet. The resulting sheet was aged by storing it at 125°C for 1 hour and then at 100°C for 12 hours, to obtain a pre-injection-molded thermoplastic polyurethane sheet. The resulting pre-injection-molded thermoplastic polyurethane sheet was then subjected to the same procedure as in Example 1 to obtain a post-injection-molded thermoplastic polyurethane sheet.

[0073] Example 4 Polymer polyol 3 (772 g, 0.39 mol) was placed in a reaction vessel and heated to 80°C. After stirring, 4,4'-diphenylmethane diisocyanate (193 g, 0.77 mol) was added and the mixture was allowed to react at 100°C for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2.2.2]octane (0.0772 g) and 1,4-butanediol (35 g, 0.39 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The reaction product was cured at 80°C for 2 hours to form a sheet. The resulting sheet was aged by storing it at 125°C for 1 hour and then at 100°C for 12 hours, yielding a pre-injection-molded thermoplastic polyurethane sheet. The resulting pre-injection-molded thermoplastic polyurethane sheet was then subjected to the same procedure as in Example 1 to obtain a post-injection-molded thermoplastic polyurethane sheet.

[0074] Example 5 Polymer polyol 4 (763 g, 0.25 mol) was placed in a reaction vessel and heated to 80°C. While stirring, 4,4'-diphenylmethane diisocyanate (191 g, 0.76 mol) was added and the mixture was allowed to react at 100°C for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2.2.2]octane (0.0763 g) and 1,4-butanediol (46 g, 0.51 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The resulting reaction product was cured at 80°C for 2 hours to form a sheet. The resulting sheet was stored at 125°C for 1 hour and then at 100°C for 12 hours to obtain a pre-injection-molded thermoplastic polyurethane sheet. The resulting pre-injection-molded thermoplastic polyurethane sheet was then subjected to the same procedures as in Example 1 to obtain a post-injection-molded thermoplastic polyurethane sheet.

[0075] Example 6 Polymer polyol 5 (784 g, 0.20 mol) was placed in a reaction vessel and heated to 80°C. With stirring, 4,4'-diphenylmethane diisocyanate (172 g, 0.69 mol) was added, and the mixture was allowed to react at 100°C for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2.2.2]octane (0.0784 g) and 1,4-butanediol (44 g, 0.49 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The resulting reaction product was cured at 80°C for 2 hours to form a sheet. The resulting sheet was stored at 125°C for 1 hour and then at 100°C for 12 hours, in that order, to obtain a thermoplastic polyurethane sheet before injection molding. The resulting thermoplastic polyurethane sheet before injection molding was then subjected to the same procedure as in Example 1 to obtain a thermoplastic polyurethane sheet after injection molding.

[0076] Example 7 Polymer polyol 6 (651 g, 0.22 mol) was placed in a reaction vessel and heated to 80°C. With stirring, 4,4'-diphenylmethane diisocyanate (271 g, 1.08 mol) was added and the mixture was allowed to react at 100°C for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2.2.2]octane (0.0651 g) and 1,4-butanediol (78 g, 0.87 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The resulting reaction product was cured at 80°C for 2 hours to form a sheet. The resulting sheet was stored at 125°C for 1 hour and then at 100°C for 12 hours to obtain a pre-injection-molded thermoplastic polyurethane sheet. The resulting pre-injection-molded thermoplastic polyurethane sheet was then subjected to the same procedures as in Example 1 to obtain a post-injection-molded thermoplastic polyurethane sheet.

[0077] Example 8 Polymer polyol 1 (653 g, 0.16 mol) was placed in a reaction vessel and heated to 80°C. With stirring, 4,4'-diphenylmethane diisocyanate (266 g, 1.06 mol) was added and the mixture was allowed to react at 100°C for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2.2.2]octane (0.0653 g) and 1,4-butanediol (81 g, 0.90 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The resulting reaction product was cured at 80°C for 2 hours to form a sheet. The resulting sheet was stored at 125°C for 1 hour and then at 100°C for 12 hours to obtain a pre-injection-molded thermoplastic polyurethane sheet. The resulting pre-injection-molded thermoplastic polyurethane sheet was then subjected to the same procedures as in Example 1 to obtain a post-injection-molded thermoplastic polyurethane sheet.

[0078] Comparative Example 1 Polymer polyol R1 (795 g, 0.20 mol) was placed in a reaction vessel and heated to 80°C. After stirring, 4,4'-diphenylmethane diisocyanate (174 g, 0.70 mol) was added and the mixture was allowed to react at 100°C for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2.2.2]octane (0.159 g) and ethylene glycol (31 g, 0.50 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The resulting reaction product was cured at 80°C for 2 hours to form a sheet. The resulting sheet was aged by storing it at 125°C for 1 hour and then at 100°C for 12 hours, to obtain a pre-injection-molded thermoplastic polyurethane sheet. The resulting pre-injection-molded thermoplastic polyurethane sheet was then subjected to the same procedure as in Example 1 to obtain a post-injection-molded thermoplastic polyurethane sheet.

[0079] Comparative Example 2 Polymer polyol R2 (784 g, 0.20 mol) was placed in a reaction vessel and heated to 80°C. While stirring, 4,4'-diphenylmethane diisocyanate (172 g, 0.69 mol) was added and the mixture was allowed to react at 100°C for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2.2.2]octane (0.0784 g) and 1,4-butanediol (44 g, 0.49 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The resulting reaction product was cured at 80°C for 2 hours to form a sheet. The resulting sheet was aged by storing it at 125°C for 1 hour and then at 100°C for 12 hours, to obtain a pre-injection-molded thermoplastic polyurethane sheet. The resulting pre-injection-molded thermoplastic polyurethane sheet was then subjected to the same procedure as in Example 1 to obtain a post-injection-molded thermoplastic polyurethane sheet.

[0080] Comparative Example 3 Polymer polyol R2 (795 g, 0.20 mol) was placed in a reaction vessel and heated to 80°C. After stirring, 4,4'-diphenylmethane diisocyanate (174 g, 0.70 mol) was added and the mixture was allowed to react at 100°C for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2.2.2]octane (0.159 g) and ethylene glycol (31 g, 0.50 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The resulting reaction product was cured at 80°C for 2 hours to form a sheet. The resulting sheet was aged by storing it at 125°C for 1 hour and then at 100°C for 12 hours, to obtain a pre-injection-molded thermoplastic polyurethane sheet. The resulting pre-injection-molded thermoplastic polyurethane sheet was then subjected to the same procedure as in Example 1 to obtain a post-injection-molded thermoplastic polyurethane sheet.

[0081] Comparative Example 4 Polymer polyol R3 (611 g, 0.31 mol) was placed in a reaction vessel and heated to 80°C. While stirring, 4,4'-diphenylmethane diisocyanate (306 g, 1.22 mol) was added and the mixture was allowed to react at 100°C for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2.2.2]octane (0.0611 g) and 1,4-butanediol (83 g, 0.92 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The resulting reaction product was cured at 80°C for 2 hours to form a sheet. The resulting sheet-like product was stored under conditions of 125°C for 1 hour and then 100°C for 12 hours to obtain a thermoplastic polyurethane sheet before injection molding. The obtained thermoplastic polyurethane sheet before injection molding was then subjected to the same procedure as in Example 1 to obtain a thermoplastic polyurethane sheet after injection molding.

[0082] Comparative Example 5 Polymer polyol R4 (611 g, 0.31 mol) was placed in a reaction vessel and heated to 80°C. While stirring, 4,4'-diphenylmethane diisocyanate (306 g, 1.22 mol) was added and the mixture was allowed to react at 100°C for 30 minutes. After stopping the heating of the reaction vessel, 1,4-diazabicyclo[2,2,2]octane (0.0611) and 1,4-butanediol (83 g, 0.92 mol) at 40°C were added and stirred for 3 minutes to obtain a reaction product. The resulting reaction product was cured at 80°C for 2 hours to form a sheet. The resulting sheet-like product was stored under conditions of 125°C for 1 hour and then 100°C for 12 hours, thereby obtaining a thermoplastic polyurethane sheet before injection molding. The obtained thermoplastic polyurethane sheet before injection molding was then subjected to the same procedure as in Example 1 to obtain a thermoplastic polyurethane sheet after injection molding.

[0083]

[0084]

[0085] The compounds other than the polymer polyols represented by the abbreviations in Tables 1 and 2 are as follows: The abbreviations for the polymer polyols are as described above. MDI: 4,4'-diphenylmethane diisocyanate EG: ethylene glycol BD: 1,4-butanediol DABCO: 1,4-diazabicyclo[2.2.2]octane

[0086] The results in Tables 1 and 2 indicate that the thermoplastic polyurethanes of Examples 1 to 8 contain structural units (A) derived from a polymer polyol (a) having a terminal hydroxyl group, structural units (B) derived from a polyisocyanate (b), and structural units (C) derived from a chain extender (c), where the polymer polyol (a) contains structural units derived from a branched polyol (a1) and a polycarboxylic acid (a2) having 7 to 11 carbon atoms, and have a number average molecular weight of 500 or greater. The thermoplastic polyurethanes contain 50 to 90% by mass of structural units (A), 8 to 45% by mass of structural units (B), and 2 to 10% by mass of structural units (C), based on 100% by mass of all structural units. Therefore, compared to the thermoplastic polyurethanes of the comparative examples shown in Table 1, it was confirmed that the thermoplastic polyurethanes of Examples 1 to 8 can achieve both good heat resistance and excellent low-temperature properties. It can also be seen that the thermoplastic polyurethanes of Examples 1 to 8 maintain a low durometer A hardness even without the use of a plasticizer.

[0087] It was confirmed that the thermoplastic polyurethanes of Comparative Examples 1 and 4 had inferior heat resistance compared to the thermoplastic polyurethanes of each Example. This is thought to be because, in the thermoplastic polyurethanes of Comparative Examples 1 and 4, the structural units derived from the polycarboxylic acid constituting the polymer polyol are derived from a polycarboxylic acid having 6 carbon atoms. In addition, it was confirmed that the thermoplastic polyurethanes of Comparative Examples 2 and 3 had inferior low-temperature properties compared to the thermoplastic polyurethanes of each Example. This is thought to be because, in the thermoplastic polyurethanes of Comparative Examples 2 and 3, the structural units derived from the polycarboxylic acid constituting the polymer polyol are derived from a polycarboxylic acid having 12 carbon atoms. It was confirmed that the thermoplastic polyurethane of Comparative Example 5 had inferior heat resistance compared to the thermoplastic polyurethanes of each Example. This is thought to be because, in the thermoplastic polyurethane of Comparative Example 5, the structural units derived from the polycarboxylic acid constituting the polymer polyol are derived from caprolactone having 6 carbon atoms.

[0088] As shown in the results of the above examples, the thermoplastic polyurethane of one embodiment of the present invention can achieve both good heat resistance and excellent low-temperature properties. Furthermore, the TPU can achieve low hardness without containing a plasticizer. The TPU and thermoplastic polyurethane compositions containing the TPU are suitable for use in, for example, dialysis tubing, catheters, medical tubing, shoe soles, shoe cushioning materials, and protective films for resins and metals. Furthermore, due to their excellent heat resistance, the TPU and thermoplastic polyurethane compositions containing the TPU are also suitable for use in applications requiring use in high-temperature environments, such as automotive parts and industrial parts. Furthermore, due to their excellent low-temperature properties, the TPU and thermoplastic polyurethane compositions containing the TPU are also suitable for use in low-temperature environments, such as transport belts for handling food at low temperatures, or in cold climates.

Claims

1. A thermoplastic polyurethane comprising structural units (A) derived from a polymer polyol (a) having a terminal hydroxyl group, structural units (B) derived from a polyisocyanate (b), and structural units (C) derived from a chain extender (c), wherein the polymer polyol (a) comprises structural units derived from a branched polyol (a1) and a polycarboxylic acid (a2) having 7 to 11 carbon atoms, and has a number average molecular weight of 500 or more, and wherein, relative to 100% by mass of all structural units in the thermoplastic polyurethane, the thermoplastic polyurethane comprises 50 to 90% by mass of structural units (A), 8 to 45% by mass of structural units (B), and 2 to 10% by mass of structural units (C).

2. The thermoplastic polyurethane according to claim 1, comprising 60 to 90 mass% of said structural units (A), 8 to 38 mass% of said structural units (B), and 2 to 8 mass% of said structural units (C), based on 100 mass% of all structural units in the thermoplastic polyurethane.

3. The thermoplastic polyurethane according to claim 1 or 2, wherein the branched polyol (a1) is 3-methyl-1,5-pentanediol.

4. The thermoplastic polyurethane according to any one of claims 1 to 3, wherein the chain extender (c) is a diol having a molecular weight of less than 500.

5. The thermoplastic polyurethane according to any one of claims 1 to 4, which has a durometer A hardness, measured in accordance with JIS K 7215-1986, of HDA 95 or less.

6. The thermoplastic polyurethane according to any one of claims 1 to 5, which has a durometer A hardness measured in accordance with JIS K 7215-1986 of HDA80 or less.

7. The thermoplastic polyurethane according to any one of claims 1 to 6, which has a crystallization temperature of -15°C or lower, or has no crystallization temperature.

8. Complex modulus E of sheet produced by injection molding at 25°C ＊ Complex modulus E at 150 ° C. ＊ The ratio of [E ＊ (150°C) / E ＊ The thermoplastic polyurethane according to any one of claims 1 to 7, wherein the viscosity index (MPa) of the thermoplastic polyurethane is 0.15 or more.

9. A method for producing a thermoplastic polyurethane, comprising reacting at least 50 to 90 mass% of a polymer polyol (a) having a hydroxyl group at a terminal, 8 to 45 mass% of a polyisocyanate (b), and 2 to 10 mass% of a chain extender (c) relative to a total amount of 100 mass% of raw materials for the thermoplastic polyurethane, to obtain a thermoplastic polyurethane, wherein the polymer polyol (a) contains structural units derived from a branched polyol (a1) and a polycarboxylic acid (a2) having 7 to 11 carbon atoms, and is a polyol having a number average molecular weight of 500 or more.

10. A method for producing a thermoplastic polyurethane according to claim 9, wherein the thermoplastic polyurethane is obtained by reacting at least 60 to 90 mass% of the polymer polyol (a) having a hydroxyl group at its terminal, 8 to 38 mass% of the polyisocyanate (b), and 2 to 8 mass% of the chain extender (c), relative to 100 mass% of the total amount of raw material components for the thermoplastic polyurethane.

11. The method for producing a thermoplastic polyurethane according to claim 9 or 10, wherein the catalyst (d) is used in an amount of 0.1 to 1,000 ppm by mass relative to the total amount of the high molecular weight polyol (a), the polyisocyanate (b), and the chain extender (c).

12. A thermoplastic polyurethane composition comprising the thermoplastic polyurethane according to any one of claims 1 to 8.

13. A molded article comprising the thermoplastic polyurethane according to any one of claims 1 to 8.

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