JP2024024789A - Thermoplastic polyurethane resin elastomer and molded products - Google Patents

Abstract

The present invention provides a thermoplastic polyurethane resin elastomer that has excellent moldability and mechanical properties, and has excellent design properties due to high transparency. [Solution] A structural unit (I) derived from a bifunctional aromatic isocyanate compound, a structural unit (II) derived from a bifunctional aliphatic alcohol with a number average molecular weight of less than 300, and a number average molecular weight of 1000 determined from the hydroxyl value. A thermoplastic polyurethane resin elastomer having ~5000 polycarbonate diol-derived structural units (III). The structural unit (III) is an ester of the structural unit (A) derived from the transesterification product of a side chain aliphatic hydrocarbon dihydroxy compound and a carbonate ester, and a straight chain aliphatic hydrocarbon dihydroxy compound and a carbonate ester. Contains structural units (B) derived from exchange reaction products in a molar ratio of 3:97 to 35:65. The content of the structural unit (III) is 5 to 45 mol% based on the total molar amount of the structural units (I) to (III). [Selection diagram] None

Description

The present invention relates to a thermoplastic polyurethane resin elastomer and a molded article.
Specifically, the present invention relates to a thermoplastic polyurethane resin elastomer that has high mechanical properties and moldability required for various uses, and also has excellent design properties due to high transparency, and a method for molding the thermoplastic polyurethane resin elastomer. Regarding molded products.

Thermoplastic polyurethane resin elastomer (hereinafter referred to as "TPU") is composed of a hard segment formed by a reaction between a short-chain diol and a diisocyanate as a chain extender, and a soft segment formed by a reaction between a polyol and a diisocyanate. It is a block copolymer.
In a resin composition containing TPU, these two segments are not compatible with each other and exist in a microphase-separated state, and are formed from hard segments that form a crystalline phase due to intermolecular cohesive force mainly composed of hydrogen bonds. A higher-order structure consisting of a highly mobile matrix is formed by weak intermolecular forces (van der Waals forces) mainly between the domains formed from the soft segments and the soft segments.

Thermoplastic resins include
1) Since it does not have a crosslinked structure like rubber, it can be molded using a known melt molding method.
2) A wide range of hardness and elasticity can be obtained in the obtained molded product.
3) It has self-reinforcing properties and is easy to color.
4) It is recyclable.
However, thermoplastic polyurethane resins that merely have thermoplasticity do not satisfy the above-mentioned four performances in a well-balanced manner.

TPU has superior mechanical properties compared to other thermoplastic resins (TPE), such as polyester (TPEE), polyamide (TPAE), styrene (SBC), olefin (TPO), and polyvinyl chloride (TPVC). It has properties such as strength, elasticity, wear resistance, and oil resistance. For this reason, molded products such as films, sheets, tubes, and pipes manufactured from TPU by extrusion molding, and various molded products obtained by injection molding and the like are used for various purposes. For example, applications of extruded products include pressure hoses and fire hoses, conveyor belts and round belts, keyboards, hot melt films, water-shielding sheets, air belts, life preservers, and the like. Applications of injection molded products include casters, gears, electric plugs, snow chains, sports shoes, watch bands, protective covers for electronic devices, and parts for wearable devices.

TPU is generally obtained by reacting a diisocyanate compound, a short chain diol, and a long chain diol. Among TPUs, TPUs that use aromatic 4,4'-diphenylmethane diisocyanate (MDI) as an isocyanate compound and 1,4-butanediol (1,4BG) as a chain extender are the most widely used. There is.

Long-chain diols include polyester diols, polyether diols, and polycarbonate diols. Polyester diols have excellent mechanical strength and abrasion resistance of the obtained TPU, but are inferior in hydrolysis resistance. Polyether diols have excellent hydrolysis resistance, low-temperature flexibility, and antibacterial properties of the obtained TPU, but are inferior in heat resistance, chemical resistance, and weather resistance. Polycarbonate diols have the disadvantage that the obtained TPU has excellent hydrolysis resistance, heat resistance, and weather resistance, but is difficult to use due to the high viscosity of the diol.

Therefore, a suitable long-chain diol is appropriately selected from polyester diols, polyether diols, and polycarbonate diols depending on the properties required of TPU. For example, polycarbonate diols are used in applications where greater durability is required. However, TPU having a homopolycarbonate diol consisting of 1,6-hexanediol as a structural unit has high crystallinity and excellent mechanical properties, but is cloudy and has insufficient transparency.

TPU is a film used to protect base materials such as automobile instrument panels and exterior surfaces of automobiles, medical catheters and tubes, polyurethane elastic fibers for clothing, soles and midsoles of sports shoes, and protective covers for electronic terminals such as smartphones. It is also used as a member of wearable devices.
In these applications, TPU is required to have excellent moldability when using known melt molding methods such as injection molding, extrusion molding, melt spinning, and the like. In addition, in applications such as films for base material protection, medical tubes, polyurethane elastic fibers for clothing, components for sports shoes, protective covers for electronic terminals, and components for wearable devices, TPU has mechanical properties. It is required to have excellent design properties due to high transparency and excellent design properties.

Patent Document 1 proposes TPU which is obtained from an alicyclic or alicyclic diisocyanate, a high molecular weight diol, and an alicyclic diol and has excellent mechanical strength and transparency as well as excellent weather resistance.

In Patent Document 2, a polyurethane based on polycarbonate diol derived from neopentyl glycol has a good texture, flexibility, and high heat resistance when used in artificial leather applications, and the paint produced using this polyurethane has a soft texture. It is said to improve touchability and operability.

Japanese Patent Application Publication No. 2000-178340 Japanese Patent Application Publication No. 2015-166466

However, the TPUs disclosed in Patent Documents 1 and 2 do not satisfactorily satisfy all three required properties: moldability during melt molding, mechanical properties, and transparency.

The present invention aims to solve these problems. That is, an object of the present invention is to provide a thermoplastic polyurethane resin elastomer that has excellent moldability and mechanical properties, and also has excellent design properties due to high transparency.

As a result of repeated studies to solve the above problems, the present inventors have discovered that a thermoplastic polyurethane resin elastomer using a specific copolymerized polycarbonate diol, a specific polyisocyanate, and a specific aliphatic alcohol in a specific ratio has been developed. The inventors have discovered that the problem can be solved, and have arrived at the present invention.

That is, the gist of the present invention is as follows.

[1] Structural unit (I) derived from a difunctional aromatic isocyanate compound, structural unit (II) derived from a difunctional aliphatic alcohol with a number average molecular weight of less than 300, and number average molecular weight determined from the hydroxyl value A thermoplastic polyurethane resin elastomer having a structural unit (III) derived from a polycarbonate diol having 1,000 or more and 5,000 or less,
The structural unit (III) is a repeating unit (A) represented by the following formula (A) and a repeating unit (B) represented by the following formula (B), (A):(B)=3:97 Containing within a molar ratio of ~35:65,
The content ratio of the structural unit (III) in the thermoplastic polyurethane resin elastomer is based on 100 mol% of the total molar amount of the structural unit (I), the structural unit (II), and the structural unit (III), 5 mol% or more and 45 mol% or less,
under conditions such that the equivalent ratio of the isocyanate group equivalent of the bifunctional aromatic isocyanate compound to the sum of the hydroxyl equivalent of the difunctional aliphatic alcohol and the hydroxyl equivalent of the polycarbonate diol is within the range of 0.98 or more and 1.20 or less. , a thermoplastic polyurethane resin elastomer obtained by reacting the difunctional aliphatic alcohol, the polycarbonate diol, and the difunctional aromatic isocyanate compound.

[The above formula (A) represents a structural unit derived from a transesterification product of a side chain aliphatic carbon hydrogen dihydroxy compound and a carbonate ester. R ¹ and R ² are each independently an alkyl group having 1 to 4 carbon atoms, and within the above range of carbon atoms, an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, or a substituent containing these atoms. May have. ]

[The above formula (B) represents a structural unit derived from a transesterification product of a linear aliphatic hydrocarbon dihydroxy compound and a carbonate ester. R ³ represents a straight chain aliphatic hydrocarbon group having 3 or 4 carbon atoms. ]

[2] The thermoplastic polyurethane resin elastomer according to [1], wherein the repeating unit (A) has a structural unit derived from a transesterification product of neopentyl glycol and carbonate ester.

[3] In the structural unit (III), the molar ratio of the repeating unit (A) and the repeating unit (B) is within the range of (A):(B) = 4:96 to 29:71. The thermoplastic polyurethane resin elastomer according to [1] or [2].

[4] The thermoplastic polyurethane resin elastomer according to any one of [1] to [3], which has a total light transmittance of 85% or more as measured in accordance with JIS K7361-1.

[5] The thermoplastic polyurethane resin elastomer according to any one of [1] to [4], which has a tensile strength of 55 MPa or more as measured in accordance with ISO 037-02.

[6] The thermoplastic polyurethane resin elastomer according to any one of [1] to [5], which can be injection molded in a molding cycle of 70 seconds or less.

[7] The thermoplastic polyurethane resin elastomer according to any one of [1] to [6], wherein the linear aliphatic hydrocarbon dihydroxy compound is 1,4-butanediol.

[8] The bifunctional aromatic isocyanate compound is 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, and 3,3'-dimethyl-4,4'- The thermoplastic polyurethane resin elastomer according to any one of [1] to [7], which is at least one member selected from the group consisting of biphenylene diisocyanate.

[9] The difunctional aliphatic alcohol is at least one selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. The thermoplastic polyurethane resin elastomer according to any one of [1] to [8], which is one type.

[10] A molded article comprising the thermoplastic polyurethane resin elastomer according to any one of [1] to [9].

According to the present invention, there is provided a thermoplastic polyurethane resin elastomer having high mechanical properties and moldability, and furthermore, excellent designability due to high transparency, and a molded article thereof.
The thermoplastic polyurethane resin elastomer of the present invention has high mechanical properties and moldability, and also has excellent design properties due to its high transparency, so it can be used in films, tubes, elastic fibers, protective covers for electronic terminal equipment, and wafers. It can be suitably used for members such as bull devices.

Embodiments of the present invention will be described in detail below. The present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist.

As used herein, the term "structural unit" refers to a unit derived from a raw material compound used in the production of a thermoplastic polyurethane resin elastomer, which is formed by polymerization of the raw material compound, and is optional in the resulting polymer. The partial structure sandwiched between the connecting groups is shown. It also includes a partial structure in which one end of the polymer is a linking group and the other is a polymerization-reactive group. The structural unit may be a unit directly formed by a polymerization reaction, or a part of the unit may be converted into another structure by treating the obtained polymer.
In this specification, "repeating unit" has the same meaning as "structural unit".
In this specification, unless otherwise specified, "~" is used to include the numerical values described before and after it as a lower limit and an upper limit.
In this specification, "mass %" indicates the content ratio of a predetermined component contained in 100 mass % of the total amount.

[Thermoplastic polyurethane resin elastomer]
The thermoplastic polyurethane resin elastomer of the present invention has a structural unit (I) derived from a bifunctional aromatic isocyanate compound (hereinafter simply referred to as "bifunctional aromatic isocyanate compound") described below, and a number average molecular weight of 300. Structural unit (II) derived from a bifunctional aliphatic alcohol (hereinafter simply referred to as "bifunctional aliphatic alcohol") with a number average molecular weight of 1000 to 5000, as determined from the hydroxyl value described below. It is a polymer having a structural unit (III) derived from a certain polycarbonate diol (hereinafter simply referred to as "polycarbonate diol").

The thermoplastic polyurethane resin elastomer of the present invention has good mechanical properties and moldability by containing the structural unit (I).
The thermoplastic polyurethane resin elastomer of the present invention has good mechanical properties by containing the structural unit (II).
The thermoplastic polyurethane resin elastomer of the present invention has good mechanical properties and moldability due to the inclusion of the structural unit (III), and also has excellent design properties due to high transparency.

Furthermore, in the thermoplastic polyurethane resin elastomer of the present invention, the structural unit (III) comprises a repeating unit (A) represented by the following formula (A) and a repeating unit (B) represented by the following formula (B). , (A):(B)=within a molar ratio of 3:97 to 35:65.

[The above formula (A) represents a structural unit derived from a transesterification reaction product between a side chain type aliphatic carbon hydrogen dihydroxy compound and a carbonate ester. R ¹ and R ² are each independently an alkyl group having 1 to 4 carbon atoms, and within the above range of carbon atoms, an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, or a substituent containing these atoms. May have. ]

[The above formula (B) represents a structural unit derived from a transesterification product of a linear aliphatic hydrocarbon dihydroxy compound and a carbonate ester. R ³ represents a straight chain aliphatic hydrocarbon group having 3 or 4 carbon atoms. ]

Furthermore, in the thermoplastic polyurethane resin elastomer of the present invention, the content of the structural unit (III) is 100 mol% of the total molar amount of the structural unit (I), the structural unit (II), and the structural unit (III). The range is from 5 mol% to 45 mol%.

Furthermore, in the thermoplastic polyurethane resin elastomer of the present invention, the equivalent ratio of the isocyanate group equivalent of the bifunctional aromatic isocyanate compound to the sum of the hydroxyl group equivalent of the bifunctional aliphatic alcohol and the hydroxyl group equivalent of the polycarbonate diol is 0.98. It is obtained by reacting the bifunctional aliphatic alcohol, the polycarbonate diol, and the bifunctional aromatic isocyanate compound under conditions of 1.20 or less.

[Raw material compound for thermoplastic polyurethane resin elastomer]
The raw material compounds used for producing the thermoplastic polyurethane resin elastomer of the present invention will be explained below.

<Raw material isocyanate compound>
The isocyanate compound as a raw material compound used for producing the thermoplastic polyurethane resin elastomer of the present invention is a difunctional aromatic compound described below as a raw material compound for forming the structural unit (I) of the thermoplastic polyurethane resin elastomer of the present invention. Contains an isocyanate compound as an essential component.

<Bifunctional aromatic isocyanate compound>
The bifunctional aromatic isocyanate compound in the present invention is a raw material compound for forming the structural unit (I) of the thermoplastic polyurethane resin elastomer of the present invention. That is, the structural unit (I) of the thermoplastic polyurethane resin elastomer of the present invention includes a structural unit derived from the bifunctional aromatic isocyanate compound.
Specifically, the bifunctional aromatic isocyanate compound in the present invention is a bifunctional aromatic isocyanate compound containing two isocyanate groups in one molecule, and known aromatic polyisocyanate compounds can be used.

More specifically, the bifunctional aromatic isocyanate compound in the present invention includes 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, 3,3'-dimethyl-4 , 4'-biphenylene diisocyanate, 4,4'-diphenyl diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4' Aromatic diisocyanates such as -dibenzyl diisocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, polymethylene polyphenylisocyanate, and m-tetramethylxylylene diisocyanate. Among these, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, 3,3'- Dimethyl-4,4'-biphenylene diisocyanate is preferred, and 4,4'-diphenylmethane diisocyanate is most preferred.
As the bifunctional aromatic isocyanate compound in the present invention, one type of the above-mentioned aromatic diisocyanates may be used alone, or two or more types may be used in combination.

As the raw material isocyanate compound, in addition to the above-mentioned bifunctional aromatic isocyanate compounds, bifunctional aliphatic (including those having an alicyclic structure) isocyanate compounds may be used. When a bifunctional aliphatic isocyanate compound is used in combination, the content of the bifunctional aliphatic isocyanate compound is preferably 10 mol% or less, preferably 10 mol% or less, based on the total molar amount of the isocyanate compound used as a raw material compound. is 5 mol% or less, more preferably 2 mol% or less. If the content of the bifunctional aliphatic isocyanate compound in the raw material isocyanate compound exceeds 10 mol%, the mechanical properties of the resulting thermoplastic polyurethane resin elastomer will deteriorate.

As the raw material isocyanate compound, a monoisocyanate compound containing one isocyanate group can be used in combination as long as the physical properties of the resulting thermoplastic polyurethane resin elastomer do not change significantly. When a monoisocyanate compound containing one isocyanate group is used in combination, the content thereof is preferably 5 mol% or less, more preferably 3 mol% or less, based on 100 mol% of the total molar amount of the isocyanate compound used as a raw material compound. It is not more than mol %, more preferably not more than 1 mol %. If the content of the monoisocyanate compound containing one isocyanate group exceeds 5 mol %, the molecular weight of the resulting thermoplastic polyurethane resin elastomer will decrease, and durability such as chemical resistance will decrease.

As the raw material isocyanate compound, it is also possible to use an isocyanate compound containing three or more isocyanate groups as long as the physical properties of the obtained thermoplastic polyurethane resin elastomer do not change significantly. When an isocyanate compound containing three or more isocyanate groups is used together, the content thereof is preferably 3 mol% or less, more preferably 1 mol%, based on 100 mol% of the total molar amount of the isocyanate compound used as a raw material compound. % or less, more preferably 0.5 mol% or less. If the content of the isocyanate compound containing three or more isocyanate groups exceeds 3 mol%, a crosslinked structure will be introduced in the resulting thermoplastic polyurethane resin elastomer, resulting in decreased melting properties and impaired molding properties. Or, when polymerizing the raw material compound, a gelation reaction may occur and polymerization may not be possible.

<Raw material aliphatic alcohol>
The aliphatic alcohol as a raw material compound acts as a chain extender in the synthesis of the thermoplastic polyurethane resin elastomer and is selected from low molecular weight polyols having at least two active hydrogens that react with isocyanate groups.
The aliphatic alcohol as a raw material compound used for producing the thermoplastic polyurethane resin elastomer of the present invention is a raw material compound for forming the structural unit (II) of the thermoplastic polyurethane resin elastomer of the present invention. It contains a bifunctional aliphatic alcohol having a molecular weight of less than 300% (hereinafter referred to as "bifunctional aliphatic alcohol in the present invention") as an essential component.

<Bifunctional aliphatic alcohol>
The difunctional aliphatic alcohol in the present invention is a raw material compound for forming the structural unit (II) of the thermoplastic polyurethane resin elastomer of the present invention. That is, the structural unit (II) of the thermoplastic polyurethane resin elastomer of the present invention includes a structural unit derived from the difunctional aliphatic alcohol.
The difunctional aliphatic alcohol in the present invention can be selected from low molecular weight polyols having at least two active hydrogens that react with isocyanate groups.
As the difunctional aliphatic alcohol in the present invention, specifically, various known difunctional aliphatic alcohols whose functional group is only a hydroxyl group and whose number average molecular weight determined from the hydroxyl value is less than 300 may be used. can.

More specifically, the difunctional aliphatic alcohol in the present invention includes ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8 - Straight chain diols such as octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol; 2-methyl-1,3-propanediol, 2,2-dimethyl-1, 3-propanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-heptanediol, 1,4-dimethylolhexane, 2- Ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, Diols with branched chains such as dimer diol; diols with ether groups such as diethylene glycol and propylene glycol; alicyclics such as 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and 1,4-dihydroxyethylcyclohexane Examples include diols having a structure.
As the bifunctional aliphatic alcohol in the present invention, one type of the above-mentioned diols may be used alone, or two or more types may be used in combination.

Even when two or more diols from among these diols are used together as the difunctional aliphatic alcohol in the present invention, the content ratio of the difunctional aliphatic alcohol used as the raw material compound When the total molar amount of alcohol is 100 mol%, it is preferably 70 mol% or more, more preferably 90 mol% or more, and most preferably 98 mol% or more. If the content of the difunctional aliphatic alcohol in the raw material aliphatic alcohol is less than 70 mol%, the mechanical properties of the resulting thermoplastic polyurethane resin elastomer may deteriorate.

Among the above-mentioned difunctional aliphatic alcohols, the obtained thermoplastic polyurethane resin elastomer has excellent mechanical properties and moldability due to excellent phase separation between soft segments and hard segments, and difunctional aliphatic alcohols can be used industrially. Since they are readily available in large quantities at low cost, they are suitable for use with straight carbon atoms of up to 12, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. Chain aliphatic diols are preferred, with 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol being more preferred.
From this point of view, the content of the linear aliphatic diol having 12 or less carbon atoms as described above should be 90 mol% or more, with the total molar amount of the aliphatic alcohol used as a raw material compound being 100 mol%. is preferred.
When a diol having a side chain is used as a chain extender, the cohesive force of the hard segment of the obtained thermoplastic polyurethane resin elastomer may be reduced, and various physical properties such as mechanical properties of the obtained thermoplastic polyurethane resin elastomer may be reduced. be. Therefore, in the present invention, linear aliphatic diols are preferably used. Among these straight-chain aliphatic diols, 1,4-butanediol is most preferred in terms of the balance of physical properties.

The aliphatic alcohol as a chain extender can be used in combination with an aliphatic monoalcohol compound containing one hydroxyl group as long as the physical properties of the resulting thermoplastic polyurethane resin elastomer do not change significantly. When an aliphatic monool compound containing one hydroxyl group is used together, its content is preferably 5 mol% or less, more preferably It is 3 mol% or less, more preferably 1 mol% or less. If the content of the aliphatic monool compound exceeds 5 mol %, the molecular weight of the resulting thermoplastic polyurethane resin elastomer will decrease, and durability such as chemical resistance will decrease.

The aliphatic alcohol as a chain extender is an aliphatic polyhydric alcohol compound containing three or more hydroxyl groups, such as glycerin, trimethylolpropane, or pentaerythritol, within the range where the physical properties of the thermoplastic polyurethane resin elastomer obtained do not change significantly. It is possible to use them together. When an aliphatic polyhydric alcohol compound containing three or more hydroxyl groups is used together, the content thereof is preferably 3 mol% or less, and more preferably Preferably it is 1 mol% or less, more preferably 0.5 mol% or less. If the content of the aliphatic polyhydric alcohol containing three or more hydroxyl groups exceeds 3 mol%, a crosslinked structure will be introduced in the resulting thermoplastic polyurethane resin elastomer, resulting in decreased melting properties and poor molding properties. Otherwise, a gelation reaction may occur during polymerization of the raw material compound, making polymerization impossible.

Furthermore, as a chain extender, in addition to an aliphatic alcohol whose functional group is only a hydroxyl group and whose number average molecular weight determined from the hydroxyl value is less than 300, an aromatic alcohol having an aromatic group or an active hydrogen compound other than a hydroxyl group, e.g. It is possible to use a compound containing an amino group, a carboxyl group, etc. in combination as long as the physical properties of the resulting thermoplastic polyurethane resin elastomer do not change significantly. When these are used together, their content should be 5 mol% or less, based on 100 mol% of the total molar amount of the aliphatic alcohol, aromatic alcohol, and/or active hydrogen compound other than hydroxyl group used as the raw material compound. is preferable, more preferably 3 mol% or less, and most preferably 1 mol% or less. When the content of compounds other than these aliphatic alcohols exceeds 5 mol %, durability such as weather resistance, hue, and hydrolysis resistance of the thermoplastic polyurethane resin elastomer obtained is reduced.

<Polycarbonate diol whose number average molecular weight determined from hydroxyl value is 1000 or more and 5000 or less>
A polycarbonate diol having a number average molecular weight of 1000 or more and 5000 or less as determined from the hydroxyl value is a raw material compound for forming the structural unit (III) of the thermoplastic polyurethane resin elastomer of the present invention.
The polycarbonate diol used as a raw material compound for the thermoplastic polyurethane resin elastomer of the present invention and having a number average molecular weight of 1000 or more and 5000 or less as determined from the hydroxyl value is a copolymerized polycarbonate diol and is represented by the following formula (A). A branched repeating unit represented by the following formula (B) (hereinafter referred to as a "repeat unit (B)") and a linear repeating unit represented by the following formula (B) (hereinafter referred to as a "repeat unit (B)"). ) (Hereinafter, the polycarbonate diol in the present invention will be referred to as "copolymerized polycarbonate diol").

[The above formula (A) represents a structural unit derived from a transesterification product of a side chain aliphatic carbon hydrogen dihydroxy compound and a carbonate ester. R ¹ and R ² are each independently an alkyl group having 1 to 4 carbon atoms, and within the above range of carbon atoms, an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, or a substituent containing these atoms. May have. ]

[The above formula (B) represents a structural unit derived from a transesterification product of a linear aliphatic hydrocarbon dihydroxy compound and a carbonate ester. R ³ represents a straight chain aliphatic hydrocarbon having 3 or 4 carbon atoms. ]

A specific copolymerized polycarbonate diol having the repeating unit (A) and the repeating unit (B) is used as a raw material compound of the thermoplastic polyurethane resin elastomer, and the present invention described above as the copolymerized polycarbonate diol and the specific isocyanate compound. The thermoplastic polyurethane resin elastomer of the present invention has a specific composition ratio of the bifunctional aromatic isocyanate compound and the bifunctional aliphatic alcohol of the present invention described above as the specific aliphatic alcohol (chain extender). The molded product has high mechanical properties and moldability required for various uses, and further has excellent design properties due to high transparency.

In the copolymerized polycarbonate diol of the present invention, a straight chain aliphatic hydrocarbon dihydroxy compound having 3 or 4 carbon atoms can be used as the raw material diol forming the repeating unit (B).

In the copolymerized polycarbonate diol of the present invention, the linear aliphatic hydrocarbon dihydroxy compound forming the repeating unit (B) preferably has 4 carbon atoms. The repeating unit (B) is derived from at least one selected from 1,3-propanediol and 1,4-butanediol due to its industrial availability and molded products using the obtained thermoplastic polyurethane resin elastomer. It is preferable from the viewpoint of excellent physical properties, and more preferably derived from 1,4-butanediol.

The repeating unit (A) represents a structural unit derived from a transesterification product of a side-chain aliphatic carbon hydrogen dihydroxy compound and a carbonic acid ester, and R ¹ and R ² each independently have a carbon number of 1 to 4. It is an alkyl group, and may have an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, or a substituent containing these atoms within the above range of carbon atoms.

Specifically, the raw material compounds forming the repeating unit (A) include neopentyl glycol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2, 2-diethylpropanol, 2-ethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2,2-dipropyl-1,3-propanediol, 2-propyl-1 , 3-propanediol, 2-propyl-2-methyl-1,3-propanediol, 2-ethyl-2-propyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol etc. are exemplified.

In the repeating unit (A), the larger both ^R1 and ^R2 , which are branched chains, the lower the chemical resistance of the obtained thermoplastic polyurethane resin elastomer and the higher the glass transition temperature, resulting in less flexibility. Demovability, which is one measure of productivity, tends to decrease due to a decrease in properties and a slowing of the crystallization rate. Furthermore, the stress relaxation properties of molded products using this material tend to be too high. From these viewpoints, it is most preferable that both R ¹ and R ² are methyl groups. Therefore, as the raw material compound forming the repeating unit (A), neopentyl glycol and 2-methyl-1,3-propanediol are most preferred.

In the copolymerized polycarbonate diol of the present invention, the repeating unit (A) may contain repeating units derived from two or more types of raw material compounds. In the copolymerized polycarbonate diol, the repeating unit (B) may contain repeating units derived from two or more types of raw material compounds.
In the copolymerized polycarbonate diol of the present invention, repeating units other than the repeating unit (A) and the repeating unit (B) may be contained in the total mole of all repeating units in the copolymerized polycarbonate diol within a range that does not impair the effects of the present invention. It may be contained in an amount of 20 mol% or less when the amount is 100 mol%.

The ratio of repeating units (A) and repeating units (B) contained in the copolymerized polycarbonate diol is 3:97 to 35:65 in molar ratio, that is, (A):(B) = 3:97 to 35:65. (Hereinafter, this molar ratio will be referred to as "repeating units (A): (B)"). If the repeating unit (A): (B) is out of the above range and the repeating unit (A) is small and the repeating unit (B) is large, the polycarbonate diol will have crystallinity and the resulting thermoplastic polyurethane resin elastomer tends to become cloudy and reduce transparency. On the other hand, if the repeating unit (A):(B) is out of the above range and there are many repeating units (A) and few repeating units (B), the solidification rate from the molten state will decrease and productivity will decrease. Since polycarbonate diol has low reactivity, thermoplastic polyurethane resin elastomers obtained by the one-shot method, for example, tend to become cloudy and have reduced transparency.
The preferable range of the repeating units (A) and (B) of the copolymerized polycarbonate diol is as described in the section on physical properties of the thermoplastic polyurethane resin elastomer of the present invention, which will be described later.

A specific method for measuring the repeating units (A) and (B) of the copolymerized polycarbonate diol will be explained in detail in the Examples section below.

When the number average molecular weight determined from the hydroxyl value of the copolymerized polycarbonate diol is 1000 or more and 5000 or less, the resulting thermoplastic polyurethane resin elastomer has good mechanical properties. When the number average molecular weight is less than 1000, the glass transition temperature of the thermoplastic polyurethane resin elastomer obtained becomes high, and the flexibility of the obtained molded product is lost. When the number average molecular weight exceeds 5,000, the viscosity of the copolymerized polycarbonate diol increases, resulting in decreased workability and yield. The number average molecular weight of the copolymerized polycarbonate diol is preferably 1,300 or more and 4,000 or less, more preferably 1,500 or more and 3,000 or less.

A specific method for measuring the number average molecular weight (Mn) determined from the hydroxyl value of the copolymerized polycarbonate diol will be explained in detail in the Examples section below.

As the raw material compound for the thermoplastic polyurethane resin elastomer of the present invention, only one type of copolymerized polycarbonate diol may be used, or two or more types of copolymerized polycarbonate diol having different repeating units, molar ratios thereof, physical properties, etc. may be used.

<Production method of copolymerized polycarbonate diol>
The copolymerized polycarbonate diol in the present invention is a linear aliphatic hydrocarbon dihydroxy compound having 3 or 4 carbon atoms for introducing the repeating unit (B), specifically, 1,3-propanediol, 1,4 -butanediol, preferably 1,4-butanediol, and neopentyl glycol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3 for introducing the repeating unit (A) -Propanediol, 2,2-diethylpropanediol, 2-ethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2,2-dipropyl-1,3-propanediol , 2-propyl-1,3-propanediol, 2-propyl-2-methyl-1,3-propanediol, 2-ethyl-2-propyl-1,3-propanediol, 2-butyl-2-ethyl- 1,3-propanediol, preferably one or more side chain aliphatic hydrocarbon dihydroxy compounds such as neopentyl glycol and 2-methyl-1,3-propanediol, and one or more of the above-mentioned suitable repeating units. (A): Produced by using dihydroxy compounds as raw materials so as to fall within the range of (B) and polymerizing these dihydroxy compounds and a carbonate compound, which is a carbonate ester, in the presence of a catalyst according to a conventional method. Can be done.

The carbonate compound that can be used in the production of the copolymerized polycarbonate diol in the present invention is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include dialkyl carbonate, diaryl carbonate, and alkylene carbonate. These may be one type or multiple types. Among these carbonate compounds, diaryl carbonate is preferred from the viewpoint of reactivity.

Specific examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, diphenyl carbonate, and ethylene carbonate, with diphenyl carbonate being preferred.

When producing a copolymerized polycarbonate diol, a known transesterification catalyst can be used as necessary to promote polymerization. As the transesterification catalyst, any compound that is generally known to have transesterification ability can be used without any restriction.

Specific examples of transesterification catalysts include compounds of Group 1 metals (excluding hydrogen) of the long period periodic table (hereinafter simply referred to as "periodic table") such as lithium, sodium, potassium, rubidium, and cesium. ; Compounds of metals in Group 2 of the periodic table, such as magnesium, calcium, strontium, and barium; Compounds of metals in Group 4 of the periodic table, such as titanium and zirconium; Compounds of metals in Group 5 of the periodic table, such as hafnium; Compounds of metals in Group 5 of the periodic table, such as cobalt Compounds of metals of group 9 of the periodic table; compounds of metals of group 12 of the periodic table, such as zinc; compounds of metals of group 13 of the periodic table, such as aluminum; compounds of metals of group 14 of the periodic table, such as germanium, tin, lead; antimony, bismuth Compounds of Group 15 metals of the periodic table, such as; compounds of lanthanide metals such as lanthanum, cerium, europium, and ytterbium.
Among these transesterification catalysts, compounds of metals of Group 1 of the periodic table (excluding hydrogen), compounds of metals of group 2 of the periodic table, compounds of metals of group 4 of the periodic table, and Compounds of metals in group 5 of the periodic table, compounds of metals in group 9 of the periodic table, compounds of metals in group 12 of the periodic table, compounds of metals in group 13 of the periodic table, compounds of metals in group 14 of the periodic table are preferable, and compounds of metals in group 14 of the periodic table are preferable. Compounds of group metals (excluding hydrogen), compounds of group 2 metals of the periodic table are more preferred, and compounds of group 2 metals of the periodic table are even more preferred. Among the compounds of Group 1 metals of the periodic table (excluding hydrogen), lithium, potassium, and sodium compounds are preferred, lithium and sodium compounds are more preferred, and sodium compounds are even more preferred. Among the compounds of Group 2 metals in the periodic table, compounds of magnesium, calcium, and barium are preferred, compounds of calcium and magnesium are more preferred, and compounds of magnesium are still more preferred.
These metal compounds are mainly used as hydroxides, salts, and the like. Examples of salts when used as salts include halide salts such as chloride, bromide, and iodide; carboxylate salts such as acetate, formate, and benzoate; inorganic acid salts such as carbonate and nitrate. Sulfonic acid salts such as methanesulfonic acid, toluenesulfonic acid and trifluoromethanesulfonic acid; Phosphorus-containing salts such as phosphates, hydrogen phosphates and dihydrogen phosphate; acetylacetonate salts; and the like. Catalytic metals can also be used as alkoxides such as methoxides and ethoxides.

Among the above-mentioned transesterification catalysts, acetates, nitrates, sulfates, carbonates, phosphates, hydroxides, halides, and alkoxides of at least one metal selected from Group 2 metals of the periodic table are preferred. are used, more preferably acetates, carbonates, and hydroxides of Group 2 metals of the periodic table are used, still more preferably magnesium and calcium acetates, carbonates, and hydroxides are used, particularly preferably Acetate salts of magnesium and calcium are used, most preferably magnesium acetate.

In the production of copolymerized polycarbonate diol in the present invention, the amount of the carbonate compound used is not particularly limited, and usually, the lower limit of the molar ratio to 1 mole of the total amount of raw material dihydroxy compounds is preferably 0.35 or more, More preferably it is 0.50 or more, still more preferably 0.60 or more. On the other hand, the upper limit of the molar ratio is preferably 1.00 or less, more preferably 0.98 or less, still more preferably 0.97 or less. If the amount of the carbonate compound used exceeds the above upper limit, the proportion of the copolymerized polycarbonate diol obtained whose end groups are not hydroxyl groups may increase, or the molecular weight may not fall within the predetermined range. On the other hand, if the amount of the carbonate compound used is less than the above lower limit, polymerization may not proceed until the copolymerized polycarbonate diol reaches a predetermined molecular weight.

In producing a copolymerized polycarbonate diol, when the above-mentioned transesterification catalyst is used, the amount used is not particularly limited, and is an amount that does not affect the performance even if it remains in the obtained polycarbonate diol. It is preferable.

The upper limit of the amount of the transesterification catalyst used is preferably 500 mass ppm or less, more preferably 100 mass ppm or less, still more preferably 50 mass ppm or less, and 10 mass ppm or less as the mass ratio of the metal to the mass of the raw material dihydroxy compound. Particularly preferred. On the other hand, the lower limit of the amount of the transesterification catalyst to be used is preferably 0.01 mass ppm or more, more preferably 0.1 mass ppm or more, and still more preferably 1 mass ppm or more, as an amount in which sufficient polymerization activity is obtained.

The reaction temperature during the transesterification reaction can be arbitrarily selected as long as it provides a practical reaction rate. Usually, the lower limit of the reaction temperature is preferably 70°C, more preferably 100°C, and even more preferably 130°C. The upper limit of the reaction temperature is usually preferably 250°C, more preferably 230°C, and even more preferably 200°C. By controlling the reaction temperature to be below the above upper limit, it is possible to prevent quality problems such as coloring of the resulting copolymerized polycarbonate diol and generation of an ether structure.

In the production of copolymerized polycarbonate diol in the present invention, the upper limit of the reaction temperature throughout the entire process of transesterification is preferably 180°C or lower, more preferably 170°C or lower, and 160°C or lower. is even more preferable. By setting the upper limit of the reaction temperature to 180°C or less throughout the entire process of the transesterification reaction, it is possible to prevent the obtained copolymerized polycarbonate diol or the thermoplastic polyurethane resin elastomer using this copolymerized polycarbonate diol from becoming easily colored. Can be done.

The transesterification reaction can also be carried out at normal pressure, but since the transesterification reaction is an equilibrium reaction, the transesterification reaction can be biased toward the production system by distilling off the light boiling components produced from the system. Therefore, in the latter half of the reaction, it is generally preferable to use reduced pressure conditions to distill off light boiling components. Alternatively, it is also possible to gradually lower the pressure in the reaction system during the transesterification reaction and carry out the reaction while distilling off the light boiling components produced. Particularly in the final stage of the transesterification reaction, it is preferable to carry out the reaction while increasing the degree of vacuum in the reaction system, since by-product monoalcohols, phenols, cyclic carbonates, etc. can be distilled off. In this case, the upper limit of the reaction pressure at the end of the reaction is preferably 10 kPa or less, more preferably 5 kPa or less, and even more preferably 1 kPa or less. In order to effectively distill off light boiling components, the reaction can be carried out while passing an inert gas such as nitrogen, argon, helium, etc. into the reaction system.

When using a low-boiling carbonate compound or dihydroxy compound during the transesterification reaction, the reaction is performed near the boiling point of the carbonate compound or dihydroxy compound at the initial stage of the reaction, and as the reaction progresses, the temperature is gradually raised. By allowing the reaction to proceed further, it is possible to prevent the unreacted carbonate compound from being distilled off at the initial stage of the reaction.

Furthermore, in order to prevent these raw materials from being distilled off, it is also possible to attach a reflux tube to the reactor and carry out the reaction while refluxing the carbonate compound and dihydroxy compound. In this case, the charged raw materials are not lost and the quantitative ratio of the reagents can be adjusted accurately.

The polymerization reaction can be carried out batchwise or continuously, but it is preferably carried out continuously in view of the stability of the product. The apparatus used for the polymerization reaction may be of any type, such as a tank type, a pipe type, or a tower type, and known polymerization tanks equipped with various types of stirring blades can be used. There are no particular restrictions on the atmosphere during the heating of the apparatus, but from the viewpoint of product quality, it is preferable to carry out the heating in an inert gas such as nitrogen gas under normal pressure or reduced pressure.

The polymerization reaction is terminated when the desired molecular weight is reached while measuring the molecular weight of the copolymerized polycarbonate diol produced. The reaction time required for polymerization varies greatly depending on the dihydroxy compound and carbonate compound used, and the presence or absence and type of catalyst used, so it cannot be absolutely specified, but it is usually 50 hours or less, preferably 20 hours or less. The heating time is more preferably 10 hours or less.

When a catalyst is used during the polymerization reaction, the catalyst usually remains in the copolymerized polycarbonate diol obtained, and the remaining catalyst may make it impossible to control the polyurethanization reaction. In order to suppress the influence of this remaining catalyst, it is preferable to add a catalyst deactivator such as a phosphorus compound in an approximately equimolar amount to the transesterification catalyst used to inactivate the transesterification catalyst. Furthermore, after adding the catalyst deactivator, the transesterification catalyst can be efficiently deactivated by heat treatment or the like as described later.

Phosphorous compounds used to deactivate transesterification catalysts include, for example, inorganic phosphoric acids such as phosphoric acid and phosphorous acid, dibutyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, and nitrous phosphate. Examples include organic phosphate esters such as triphenyl phosphate. These may be used alone or in combination of two or more.

The amount of the phosphorus compound to be used is not particularly limited, and may be approximately equimolar to the transesterification catalyst used. Specifically, the upper limit of the amount of the phosphorus compound used is preferably 5 mol or less, more preferably 2 mol or less, per 1 mol of the transesterification catalyst used. On the other hand, the lower limit of the amount of the phosphorus compound to be used is preferably 0.8 mol or more, more preferably 1.0 mol or more. If a smaller amount of phosphorus compound is used, the transesterification catalyst in the reaction product will not be sufficiently inactivated, and the resulting copolycarbonate diol will be used as a raw material for producing thermoplastic polyurethane resin elastomer. In some cases, it may not be possible to sufficiently reduce the reactivity of the copolymerized polycarbonate diol with respect to isocyanate groups. Furthermore, if a phosphorus compound exceeding this range is used, the resulting copolycarbonate diol may be colored.

Although deactivation of the transesterification catalyst by adding a phosphorous compound can be performed at room temperature, heat treatment is more efficient. The upper limit of the temperature of this heat treatment is not particularly limited, and is preferably 180°C or lower, more preferably 150°C or lower, still more preferably 120°C or lower, particularly preferably 100°C or lower. On the other hand, the lower limit of the temperature of the heat treatment is preferably 50°C or higher, more preferably 60°C or higher, and still more preferably 70°C or higher. If the temperature is lower than this, deactivation of the transesterification catalyst takes time and is not efficient, and the degree of deactivation may be insufficient. At temperatures above 180°C, the resulting copolycarbonate diol may be colored.

The time for reacting with the phosphorus compound is not particularly limited, but is usually 1 to 5 hours.

The amount of catalyst remaining in the copolymerized polycarbonate diol is preferably 100 mass ppm or less, more preferably 10 mass ppm or less in terms of metal, from the viewpoint of controlling the polyurethanization reaction. The amount of catalyst remaining in the copolymerized polycarbonate diol is preferably 0.01 mass ppm or more, particularly 0.1 mass ppm or more, especially 5 mass ppm or more in terms of metal.

The reaction product is purified to remove impurities that do not have a hydroxyl group at the end of the polymer, phenols, raw material dihydroxy compounds, carbonate compounds, by-produced light-boiling cyclic carbonates, and added catalysts. You can.

For purification, a method of distilling off light boiling compounds can be adopted. The specific method of distillation is not particularly limited in its form, such as vacuum distillation, steam distillation, and thin film distillation, and any method can be employed, but thin film distillation is particularly effective.

Although there are no particular limitations on the thin film distillation conditions, the upper limit of the temperature during thin film distillation is preferably 250°C or lower, and preferably 200°C or lower. On the other hand, the lower limit of the temperature during thin film distillation is preferably 120°C or higher, more preferably 150°C or higher. By setting the lower limit of the temperature during thin film distillation to the above value, the effect of removing light boiling components is sufficient. By setting the upper limit of the temperature during thin film distillation to 250° C. or less, it is possible to prevent the copolymerized polycarbonate diol obtained after thin film distillation from being colored.

The upper limit of the pressure during thin film distillation is preferably 500 Pa or less, more preferably 150 Pa or less, even more preferably 70 Pa or less, and particularly preferably 60 Pa or less. By controlling the pressure during thin film distillation to be below the above upper limit, a sufficient effect of removing light boiling components can be obtained.

The upper limit of the temperature for keeping the copolymerized polycarbonate diol immediately before thin film distillation is preferably 250°C or lower, more preferably 150°C or lower. By keeping the heat retention temperature below the above upper limit, it is possible to prevent the copolymerized polycarbonate diol obtained after thin film distillation from being colored. On the other hand, the lower limit of the temperature is preferably 80°C or higher, more preferably 120°C or higher. By setting the temperature at which the copolymerized polycarbonate diol is kept warm immediately before thin film distillation to be equal to or higher than the above lower limit, it is possible to prevent a decrease in fluidity of the copolymerized polycarbonate diol immediately before thin film distillation.

In order to remove water-soluble impurities from the copolymerized polycarbonate diol produced, the copolymerized polycarbonate diol may be washed with water, alkaline water, acidic water, a solution containing a chelating agent, or the like. In that case, the compound to be dissolved in water can be arbitrarily selected.

When diaryl carbonate such as diphenyl carbonate is used as a raw material, phenols are produced as a by-product during the production of copolycarbonate diol. Since phenols are monofunctional compounds, they can be an inhibiting factor in the production of thermoplastic polyurethane resin elastomers, and the urethane bonds formed by phenols have weak bonding strength, making it difficult for subsequent processes. etc., it may dissociate due to heat, and isocyanates and phenols may be regenerated and cause problems. Furthermore, since phenols are also irritating substances, it is preferable that the amount of phenols remaining in the copolymerized polycarbonate diol is as small as possible. Specifically, the residual amount of phenols in the copolymerized polycarbonate diol is preferably 1000 ppm or less, more preferably 500 ppm or less, still more preferably 300 ppm or less, particularly preferably 100 ppm or less, as a mass ratio to the copolymerized polycarbonate diol. . In order to reduce the phenols in the copolymerized polycarbonate diol, as mentioned above, the pressure of the polymerization reaction of the copolymerized polycarbonate diol is set to a high vacuum of 1 kPa or less in absolute pressure, or thin film distillation is performed after the polymerization reaction of the copolymerized polycarbonate diol. It is effective to do the following.

The carbonate compound used as a raw material during production may remain in the copolymerized polycarbonate diol. The residual amount of the carbonate compound in the copolymerized polycarbonate diol is not particularly limited, but it is preferably as small as possible, and the upper limit of the residual amount of the carbonate compound is preferably 5% by mass or less as a mass ratio to the copolymerized polycarbonate diol. , more preferably 3% by mass or less, still more preferably 1% by mass or less. If the carbonate compound content of the copolymerized polycarbonate diol is too large, the reaction during polyurethanization may be inhibited. On the other hand, the lower limit of the residual amount of the carbonate compound is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.01% by mass or more, and even more preferably no carbonate compound ( 0% by mass).

The dihydroxy compound used during production may remain in the copolymerized polycarbonate diol. The remaining amount of the dihydroxy compound in the copolymerized polycarbonate diol is not particularly limited, but it is preferably as small as possible, and the upper limit of the remaining amount of the dihydroxy compound is preferably 1% by mass or less as a mass ratio to the copolymerized polycarbonate diol. , more preferably 0.1% by mass or less, still more preferably 0.05% by mass or less. If the remaining amount of the dihydroxy compound in the copolymerized polycarbonate diol is too large, the resulting thermoplastic polyurethane resin elastomer may not have desired physical properties because the molecular length of the soft segment portion is too short.

The copolymerized polycarbonate diol may contain a cyclic carbonate (cyclic oligomer) that is produced as a by-product during production. For example, when 2,2-dialkyl-1,3-propanediol is used as the raw material dihydroxy compound for the repeating unit (A), 5,5-dialkyl-1,3-dioxan-2-one or further these compounds A cyclic carbonate formed from two or more molecules of is sometimes produced and contained in the copolymerized polycarbonate diol. More specifically, when 2,2-dimethyl-1,3-propanediol is used, 5,5-dimethyl-1,3-dioxan-2-one or two or more molecules of these compounds are used. A cyclic carbonate formed from the above may be produced and contained in the copolymerized polycarbonate diol. These cyclic carbonates may cause side reactions in the polyurethanization reaction and cause turbidity. It is preferable to remove as much as possible by thin film distillation or the like after synthesis of the polymerized polycarbonate diol. Although the upper limit of the content of cyclic carbonate such as 5,5-dialkyl-1,3-dioxan-3-one contained in the copolymerized polycarbonate diol is not limited, it is preferably 3 as a mass ratio to the copolymerized polycarbonate diol. It is less than 1 mass %, more preferably 1 mass % or less, even more preferably 0.5 mass % or less, particularly preferably no cyclic carbonate (0 mass %).

<Polyols other than copolymerized polycarbonate diol>
In the polyurethane forming reaction for producing the thermoplastic polyurethane resin elastomer of the present invention, polyols other than the above-mentioned copolymerized polycarbonate diol may be used in combination, if necessary, within a range that does not affect the physical properties of the thermoplastic polyurethane resin elastomer. You can.

Polyols other than the copolymerized polycarbonate diol are not particularly limited as long as they are used in normal polyurethane production, and include known polyols such as polyester polyols, polycaprolactone polyols, polyalkylene ether glycols, Examples include polycarbonate polyols other than copolymerized polycarbonate diols.

Examples of the polyester polyol include those obtained by dehydration condensation of an aliphatic dibasic acid such as adipic acid, an aromatic dibasic acid such as phthalic anhydride, and an aliphatic glycol.
Examples of the polyalkylene polyol ether glycol include poly(oxyethylene) glycol and poly(oxypropylene) glycol obtained by addition polymerization of ethylene oxide and propylene oxide, and polytetramethylene obtained by ring-opening polymerization of tetrahydrofuran. An example is ether glycol (PTMG). In addition, all known polyols such as polyolefin polyols can be used in combination.

Polyols other than the copolymerized polycarbonate diol mentioned above may be used alone or in combination of two or more.

When polyester polyol and polycaprolactone polyol are used in excess, there is a possibility that durability such as hydrolysis resistance of the thermoplastic polyurethane resin elastomer obtained may be reduced. Moreover, if polyalkylene ether glycol is used in excess, there is a risk that the durability of the weather resistance and chemical resistance of the thermoplastic polyurethane resin elastomer obtained may be reduced. Therefore, when these polyols are used, they are used in combination within a range that does not affect the physical properties of the thermoplastic polyurethane resin elastomer.

From this point of view, the content of the copolymerized polycarbonate diol is usually 80 mol% with respect to the total 100 mol% of the copolymerized polycarbonate diol and polyols other than the copolymerized polycarbonate diol used for producing the thermoplastic polyurethane resin elastomer of the present invention. The content is preferably 90 mol% or more, more preferably 95 mol% or more, and most preferably 98 to 100 mol%. If the content of the copolymerized polycarbonate diol is small, the mechanical properties and excellent transparency of the thermoplastic polyurethane resin elastomer molded article, which are the features of the present invention, may be impaired.

[Method for producing thermoplastic polyurethane resin elastomer]
The thermoplastic polyurethane resin elastomer of the present invention comprises the above-mentioned bifunctional aromatic isocyanate compound, a bifunctional aliphatic alcohol having a number average molecular weight of less than 300 as a chain extender, and a number average molecular weight of 1000 or more determined from the hydroxyl value. It can be produced by a normal polyurethanization reaction generally used experimentally or industrially, except that a copolymerized polycarbonate diol having a molecular weight of 5,000 or less is used in a predetermined ratio.

<One-stage method (one-shot method)>
The thermoplastic polyurethane resin elastomer of the present invention can be efficiently produced by reacting the copolymerized polycarbonate diol, the isocyanate compound, and the chain extender at a temperature ranging from 100°C to 220°C. As a one-stage industrial manufacturing method, known methods described in JP-A-2004-182980 and others can be applied.

<Two-step method (prepolymer method)>
A two-step method in which a mixture of a prepolymer and an isocyanate compound having an isocyanate group at the terminal is produced by reacting a copolymerized polycarbonate diol with an excess of an isocyanate compound in advance, and then reacting with a chain extender is also used. It can be applied to plastic polyurethane resin elastomers.

<Catalyst>
When producing the thermoplastic polyurethane resin elastomer of the present invention, a catalyst may be used for the urethanization reaction. Examples of the urethanization reaction catalyst include organic tin compounds, organic zinc compounds, organic bismuth compounds, organic titanium compounds, organic zirconium compounds, and amine compounds. The urethanization reaction catalyst may be used alone or in combination of two or more.

When using a urethanization reaction catalyst, it is recommended to adjust the amount to 0.1 to 100 ppm by mass based on the mass of the thermoplastic polyurethane resin elastomer. If a urethanization reaction catalyst of 0.1 mass ppm or more is used, the initial molecular weight will be maintained at a sufficiently high level even after the thermoplastic polyurethane resin elastomer is molded, and even the molded product will retain the original molecular weight of the thermoplastic polyurethane resin elastomer. It becomes easier to effectively exhibit physical properties.

[Physical properties of thermoplastic polyurethane resin elastomer]
The thermoplastic polyurethane resin elastomer of the present invention comprises the aforementioned bifunctional aromatic isocyanate compound, a bifunctional aliphatic alcohol having a number average molecular weight of less than 300 as determined from the hydroxyl value, and a number average molecular weight of 1000 or more and 5000 or more as determined from the hydroxyl value. It is obtained by reacting the following copolymerized polycarbonate diols, and satisfies (1) to (3) below.

(1) In the structural unit (III), a repeating unit (A) represented by the following formula (A) and a repeating unit (B) represented by the following formula (B) are combined into a repeating unit (A): (B )=3:97 to 35:65 molar ratio.

[The above formula (A) represents a structural unit derived from a transesterification product of a side chain aliphatic carbon hydrogen dihydroxy compound and a carbonate ester. R ¹ and R ² are each independently an alkyl group having 1 to 4 carbon atoms, and within the above range of carbon atoms, an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, or a substituent containing these atoms. May have. ]

[The above formula (B) represents a structural unit derived from a transesterification product of a linear aliphatic hydrocarbon dihydroxy compound and a carbonate ester. R ³ represents a straight chain aliphatic hydrocarbon having 3 or 4 carbon atoms. ]

(2) The content ratio of the structural unit (III) in the thermoplastic polyurethane resin elastomer is based on 100 mol% of the total molar amount of the structural unit (I), the structural unit (II), and the structural unit (III). 5 mol% or more and 45 mol% or less.

(3) Equivalent ratio of the isocyanate group equivalent of the bifunctional aromatic isocyanate compound to the sum of the hydroxyl group equivalent of the bifunctional aliphatic alcohol and the hydroxyl group equivalent of the polycarbonate diol (hereinafter referred to as "NCO/OH equivalent ratio") ) is 0.98 or more and 1.20 or less by reacting the difunctional aliphatic alcohol, the polycarbonate diol, and the difunctional aromatic isocyanate compound.

<Repeat unit (A): (B)>
In the thermoplastic polyurethane resin elastomer of the present invention, the repeating unit (A) and repeating unit (B) are contained in a molar ratio of repeating unit (A): repeating unit (B) = 3:97 to 35:65. include.
When the repeating unit (A):(B) ratio is less than 3:97, the thermoplastic polyurethane resin elastomer has insufficient mechanical properties. On the other hand, a thermoplastic polyurethane resin elastomer having a repeating unit (A):(B) ratio of more than 35:65 has insufficient moldability and transparency. The lower limit of repeating units (A):(B) is preferably 4:96 or more, more preferably 8:92 or more, and even more preferably 12:88 or more. Further, the upper limit of repeating units (A):(B) is preferably 32:68 or less, more preferably 29:71 or less, and even more preferably 27:73 or less.

<Content ratio of structural unit (III)>
The content ratio of the structural unit (III) in the thermoplastic polyurethane resin elastomer of the present invention is based on 100 mol% of the total molar amount of the structural unit (I), the structural unit (II), and the structural unit (III). and is within the range of 5 mol% or more and 45 mol% or less.
If the content of the structural unit (III) is less than 5 mol%, the thermoplastic polyurethane resin elastomer will have insufficient mechanical properties. On the other hand, a thermoplastic polyurethane resin elastomer containing more than 45 ol % of the structural unit (III) may have insufficient moldability and transparency. The lower limit of the content of the structural unit (III) is preferably 8 mol% or more, more preferably 11 mol% or more. Further, the upper limit of the content of the structural unit (III) is preferably 35 mol% or less, more preferably 25 mol% or less.

<NCO/OH equivalent ratio>
In the thermoplastic polyurethane resin elastomer of the present invention, the equivalent ratio of the isocyanate group equivalent of the difunctional aromatic isocyanate compound to the sum of the hydroxyl group equivalent of the difunctional aliphatic alcohol and the hydroxyl group equivalent of the copolymerized polycarbonate diol is 0.98. It is obtained by reacting the difunctional aliphatic alcohol, the polycarbonate diol, and the difunctional aromatic isocyanate compound under conditions within the range of 1.20 or less.

The hydroxyl equivalent of the copolymerized polycarbonate diol is the chemical formula weight per hydroxyl group in the copolymerized polycarbonate diol in the present invention.
The hydroxyl equivalent of the difunctional aliphatic alcohol is the chemical formula weight per hydroxyl group in the difunctional aliphatic alcohol in the present invention.
Moreover, isocyanate equivalent is the chemical formula weight per isocyanate group in the bifunctional aromatic isocyanate compound in the present invention.

When the NCO/OH equivalent ratio is less than 0.98, the thermoplastic polyurethane resin elastomer has insufficient physical properties such as tensile strength and heat resistance. On the other hand, thermoplastic polyurethane resin elastomers with an NCO/OH equivalent ratio exceeding 1.20 may form chemical crosslinks due to side reactions such as allophanate bonds, or unreacted isocyanate groups may react with moisture in the air to form amino groups. As the proportion increases, the melting characteristics may deteriorate, moldability may deteriorate, fish eyes or yellowing due to the gel may occur, and the elongation of mechanical strength may become insufficient. The lower limit of the NCO/OH equivalent ratio is preferably 0.99 or more, more preferably 1.00 or more. Further, the upper limit of the NCO/OH equivalent ratio is preferably 1.10 or less, more preferably 1.05 or less.

The NCO/OH equivalent ratio of the thermoplastic polyurethane resin elastomer of the present invention can be measured, in addition to the mass ratio of each component during polymerization, using an NMR (nuclear magnetic resonance) device with a frequency of usually 400 MHz or higher.

<Molecular weight>
The molecular weight of the thermoplastic polyurethane resin elastomer of the present invention is appropriately adjusted depending on the use of the thermoplastic polyurethane resin elastomer of the present invention to be produced, and is measured by gel permeation chromatography (GPC), although it is not particularly limited. The weight average molecular weight (Mw) in terms of polystyrene is preferably 50,000 to 500,000, more preferably 100,000 to 300,000. If the weight average molecular weight (Mw) is smaller than the above-mentioned lower limit, sufficient strength, hardness, and durability may not be obtained, and if it is larger than the above-mentioned upper limit, there is a tendency for handling properties such as moldability and processability to be impaired.

The molecular weight distribution (Mw/Mn) of the thermoplastic polyurethane resin elastomer of the present invention is preferably 1.5 to 3.5, more preferably 1.7 to 3.0, and most preferably 1.8 to 2. It is 5. When the molecular weight distribution exceeds 3.5, moldability becomes insufficient. In order to reduce the molecular weight distribution to less than 1.5, special purification treatment is required, which poses an economical problem. Molecular weight distribution can also be measured by GPC.

[Thermoplastic polyurethane resin elastomer composition]
Thermoplastic polyurethane resin elastomers may contain antioxidants, defoamers, ultraviolet absorbers, reaction regulators, plasticizers, mold release agents, reinforcing agents, fillers (inorganic By adding optional ingredients such as fillers/organic fillers), stabilizers, colorants (pigments/dyes), flame retardant improvers, light stabilizers, etc., it can be used as a thermoplastic polyurethane resin elastomer composition. can do.

Furthermore, the thermoplastic polyurethane resin elastomer of the present invention may be used with other thermoplastic polyurethane resin elastomers, such as vinyl chloride-based, styrene-based, polyolefin-based, polydiolefin-based, polyester-based, amide-based, silicon-based, etc. It can also be used as a compounded thermoplastic polyurethane resin elastomer composition.

Since the thermoplastic polyurethane resin composition of the present invention contains the thermoplastic polyurethane resin elastomer of the present invention, it has excellent mechanical properties and moldability, and also has excellent design properties due to high transparency. It can be used in various applications that require

The content of the thermoplastic polyurethane resin elastomer of the present invention in the thermoplastic polyurethane resin elastomer composition is preferably 80% by mass or more based on 100% of the total mass of the composition. If the content of the thermoplastic polyurethane resin elastomer of the present invention is 80% by mass or more, the resulting molded product will have good mechanical properties, moldability, and transparency. The content of the thermoplastic polyurethane resin elastomer of the present invention in the thermoplastic polyurethane resin elastomer composition is more preferably 90% by mass or more, and even more preferably 95% by mass or more.

The thermoplastic polyurethane resin elastomer composition can be prepared, for example, by mixing the thermoplastic polyurethane resin elastomer of the present invention, the above-mentioned additives, and other thermoplastic elastomers in a predetermined blending ratio, and using a known melt-kneading means. After melt-kneading the mixture, the obtained melt-kneaded product can be obtained, for example, in the form of pellets using a known cutting/pulverizing device such as a pelletizer. As a known melt-kneading means, kneading machines such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a pressure kneader, and a roll can be used. Alternatively, the mixture can also be used directly as a raw material for producing molded articles.

[Molding]
The molded article of the present invention is a molded article containing the thermoplastic polyurethane resin elastomer of the present invention or the thermoplastic polyurethane resin elastomer composition described above.
Alternatively, the molded article of the present invention is a molded article having the characteristics described above, which is obtained by molding the thermoplastic polyurethane resin elastomer of the present invention or the thermoplastic polyurethane resin elastomer composition described above.
The form of the molded article of the present invention is not particularly limited, but includes, for example, pellets, films, sheets, or laminated films having layers made of the thermoplastic polyurethane resin elastomer of the present invention or the thermoplastic polyurethane resin elastomer composition described above. Examples include known resin molded bodies such as.

The method of molding the thermoplastic polyurethane resin elastomer of the present invention or the thermoplastic polyurethane resin elastomer composition described above is not particularly limited, and various molding methods commonly used for thermoplastic polymers may be used. Can be done. For example, known molding methods such as injection molding, extrusion molding, press molding, blow molding, calendar molding, inflation molding, casting molding, and roll processing can be used to produce resin plates, films, sheets, tubes, and hoses. It can produce molded products of various shapes, such as belts, rolls, synthetic leather, shoe soles, automobile parts, escalator handrails, road sign members, and textiles.

[Application]
Specifically, the thermoplastic polyurethane resin elastomer of the present invention and molded products thereof can be used for pneumatic equipment used in the food and medical fields, coating equipment, analytical equipment, physical and chemical equipment, metering pumps, water treatment equipment, and industrial equipment. Examples include tubes and hoses for robots, spiral tubes, fire hoses, etc. It is also used as belts such as round belts, V-belts, and flat belts in various power transmission mechanisms, spinning machines, packing equipment, printing machines, and the like. Also used in footwear heel tops and soles, couplings, packing, pole joints, bushes, gears, equipment parts such as rolls, sporting goods, leisure goods, protective covers for electronic devices, parts for watch bands and wearable devices, etc. Can be used. Further, as automobile parts, it can be used for oil stoppers, gear boxes, spacers, chassis parts, interior parts, tire chain substitutes, etc. It can also be used for keyboard films, automobile films, curl cords, cable sheaths, bellows, conveyor belts, flexible containers, binders, synthetic leather, dipping products, adhesives, etc.

The thermoplastic polyurethane resin elastomer of the present invention or the above-mentioned thermoplastic polyurethane resin elastomer composition has excellent transparency in addition to various durability such as chemical resistance against oleic acid, and is also excellent in injection molding properties. Therefore, it is particularly suitable for sports goods, leisure goods, protective covers for electronic devices, watch bands, wearable device members, and the like.

The present invention will be explained in more detail below by giving Examples and Comparative Examples. The present invention is not limited to these examples unless it exceeds the gist thereof.

[Evaluation method of copolymerized polycarbonate diol]
The copolymerized polycarbonate diols produced in Synthesis Examples 1 to 8 were evaluated according to the following method.

<Hydroxyl value and number average molecular weight of copolymerized polycarbonate diol>
The hydroxyl value of polycarbonate diol was measured in accordance with JIS K1557-1 using a method using an acetylation reagent. Further, the number average molecular weight was determined from the hydroxyl value using the following formula (1).
Number average molecular weight = 2 x 56.1/(hydroxyl value x 10 ^-3 )...(1)

<Repeat unit (A): (B)>
The copolymerized polycarbonate diol was dissolved in CDCl ₃ and 400 MHz ¹ H-NMR (model number: AL-400, manufactured by JEOL Ltd.) was measured. From the signal position of each component, repeating unit (A) and repeating unit (B ) (repeating units (A):(B)) was determined.

<Thermal properties>
As an index of the thermal properties of the copolymerized polycarbonate diol, differential scanning calorimetry (DSC) measurement is used to observe the presence or absence of an endothermic peak and, if an endothermic peak is observed, to determine its temperature (melting point) and enthalpy of fusion. ΔH was evaluated.
Alumina was used as a standard sample, and the temperature was raised from room temperature to 180°C in a nitrogen atmosphere at a rate of ±10°C/min, then lowered to -100°C, and held for 1 minute. Thereafter, the thermal characteristics were evaluated when the temperature was raised to 180° C. again. The presence or absence of an endothermic peak due to melting of the copolymerized polycarbonate diol and the enthalpy of fusion ΔH (unit: J/g) were measured between 0 and 100°C, and the results were judged according to the following criteria.
(Judgment criteria)
Good: No endothermic peak was observed, or an endothermic peak was observed but the enthalpy of fusion was 5.0 J/g or less.
×: An endothermic peak was observed, and the enthalpy of fusion exceeded 5.0 J/g.

[Evaluation method of thermoplastic polyurethane resin elastomer]
The thermoplastic polyurethane resin elastomers produced in Examples and Comparative Examples were evaluated according to the following method.

<Injection moldability>
As an indicator of the moldability of the thermoplastic polyurethane resin elastomer, injection molding was performed using J110AD-110H (manufactured by Japan Steel Works), and cycle time was evaluated. Note that the nozzle temperature was 235° C., the injection pressure was 90 MPa, and the screw rotation speed was 80 rpm. The size of the mold used for injection molding was 120 mm long x 120 mm wide x 2 mm thick, and the mold temperature was 40°C. By adjusting the cooling time for each material, a molded product with the optimal shape and appearance was obtained. In addition, the cycle time at this time was measured and judged according to the following criteria.
(Judgment criteria)
○: Cycle time was within 70 seconds ×: Cycle time was longer than 70 seconds

<Tensile strength>
The mechanical properties of the thermoplastic polyurethane resin elastomer were evaluated by the following method.
A sheet of thermoplastic polyurethane resin elastomer having a thickness of 2 mm was punched into a size 3 dumbbell shape using a punching machine. Using a tensile tester (AGS-10kNX, manufactured by Shimadzu Corporation) and an extensometer (DSES-1000, manufactured by Shimadzu Corporation), in accordance with ISO 037-02, the distance between gauge lines was 20 mm, the tensile speed was 200 mm/min, n A tensile test was conducted under the conditions of =3. The median value of the stress at break was defined as the respective tensile strength.

<Transparency>
The transparency of the thermoplastic polyurethane resin elastomer was evaluated by the following method.
Based on JIS K7361-1, the total light transmittance of a 2 mm thick thermoplastic polyurethane resin elastomer sheet was measured and judged according to the following criteria.
(Judgment criteria)
〇: Total light transmittance is 85% or more ×: Total light transmittance is less than 85%

[Synthesis and evaluation of polycarbonate diol]
[Synthesis Example 1: Synthesis of PCD5]
In a 5L glass separable flask equipped with a stirrer, a distillate trap, and a pressure regulator, 1101.8 g of 1,4-butanediol (1,4BG) as a raw material compound for the repeating unit (A) and the repeating unit (B ) 279.5 g of neopentyl glycol (NPG) as a raw material compound, 2918.6 g of diphenyl carbonate (DPC) as a carbonate compound, 7.6 mL of an aqueous solution of magnesium acetate tetrahydrate (concentration: 8.4 g/L, magnesium acetate tetrahydrate) 64 mg) was added, and the atmosphere was replaced with nitrogen gas. While stirring the contents of the flask, the contents were heated and heated until the temperature of the contents reached 160° C. to dissolve the contents. Thereafter, the pressure inside the separable flask was lowered to 24 kPa over 2 minutes, and the reaction was allowed to proceed for 90 minutes while removing the generated phenol from the system. Next, the pressure inside the separable flask was lowered to 9.3 kPa over 90 minutes, and then further lowered to 0.4 kPa over 30 minutes to continue the reaction, and then the temperature of the contents was raised to 170°C. Then, the mixture was reacted for 60 minutes while removing the phenol and unreacted dihydroxy compound from the system to obtain 1538.4 g of a polycarbonate diol-containing composition.

0.85% by mass phosphoric acid aqueous solution: 2.6g was added to 1421.8g of the obtained polycarbonate diol-containing composition to deactivate magnesium acetate, and the liquid was sent to a thin film distillation apparatus at a flow rate of about 14g/min, Thin film distillation (temperature: 180°C, pressure: 53-67 Pa) was performed. As the thin film distillation apparatus, a special model molecular distillation apparatus MS-300 manufactured by Shibata Kagaku Co., Ltd. with an internal condenser and a jacket having a diameter of 50 mm, a height of 200 mm, and an area of 0.0314 m ² was used.

The content of phenols in the polycarbonate diol obtained by thin film distillation was 100 mass ppm or less. Moreover, the content of magnesium was 100 mass ppm or less.
The obtained polycarbonate diol is referred to as "PCD5". The evaluation results of PCD5 are shown in Table 1. Note that the content of phenols was measured using gas chromatography. The content of magnesium was measured using a neutralization reduction titration method.

[Synthesis Example 2: Synthesis of PCD7]
Into a 5L glass separable flask equipped with a stirrer, a distillate trap, and a pressure regulator, 679.4 g of 1,4-butanediol (1,4-BG) as a raw material compound for the repeating unit (A) and the repeating unit. 629.6 g of neopentyl glycol (NPG) as the raw material compound of (B), 2691.0 g of diphenyl carbonate (DPC) as the carbonate compound, 6.9 mL of magnesium acetate tetrahydrate aqueous solution (concentration: 8.4 g/L, magnesium acetate 58 mg of tetrahydrate) was added, and the atmosphere was replaced with nitrogen gas. Next, a reaction was carried out under the same conditions as in Synthesis Example 11 to obtain 1368.2 g of a copolymerized polycarbonate diol-containing composition.

2.3 g of 0.85% by mass phosphoric acid aqueous solution was added to 1261.0 g of the obtained copolymerized polycarbonate diol-containing composition to deactivate magnesium acetate, and the liquid was sent to a thin film distillation apparatus at a flow rate of about 16 g/min. Then, thin film distillation (temperature: 190°C, pressure: 53-67 Pa) was performed. As the thin film distillation apparatus, a special model molecular distillation apparatus MS-300 manufactured by Shibata Kagaku Co., Ltd. with an internal condenser and a jacket having a diameter of 50 mm, a height of 200 mm, and an area of 0.0314 m ² was used.

The content of phenols in the copolymerized polycarbonate diol obtained by thin film distillation was 100 mass ppm or less. Moreover, the content of magnesium was 100 mass ppm or less.
The obtained copolymerized polycarbonate diol is referred to as "PCD7". The evaluation results of PCD7 are shown in Table 1.

[Synthesis Example 3: Synthesis of PCD1]
1,4BG, NPG, and DPC were charged in a predetermined molar ratio, and other than that, a copolymerized polycarbonate diol-containing composition was produced based on the procedure of Synthesis Example 1, and various copolymerized polycarbonate diols were obtained by thin film distillation. Ta. The produced copolymerized polycarbonate diol is referred to as "PCD1". The evaluation results of PCD1 are shown in Table 1.

[Synthesis Example 4: Synthesis of PCD2]
1,4BG, NPG, and DPC were charged in a predetermined molar ratio, and other than that, a copolymerized polycarbonate diol-containing composition was produced based on the procedure of Synthesis Example 1, and various copolymerized polycarbonate diols were obtained by thin film distillation. Ta. The produced copolymerized polycarbonate diol is referred to as "PCD2". The evaluation results of PCD2 are shown in Table 1.

[Synthesis Example 5: Synthesis of PCD3]
1,4BG, NPG, and DPC were charged in a predetermined molar ratio, and other than that, a copolymerized polycarbonate diol-containing composition was produced based on the procedure of Synthesis Example 1, and various copolymerized polycarbonate diols were obtained by thin film distillation. Ta. The produced copolymerized polycarbonate diol is referred to as "PCD3". The evaluation results of PCD3 are shown in Table 1.

[Synthesis Example 6: Synthesis of PCD4]
1,4BG, NPG, and DPC were charged in a predetermined molar ratio, and other than that, a copolymerized polycarbonate diol-containing composition was produced based on the procedure of Synthesis Example 1, and various copolymerized polycarbonate diols were obtained by thin film distillation. Ta. The produced copolymerized polycarbonate diol is referred to as "PCD4". The evaluation results of PCD4 are shown in Table 1.

[Synthesis Example 7: Synthesis of PCD6]
1,4BG, NPG, and DPC were charged in a predetermined molar ratio, and other than that, a copolymerized polycarbonate diol-containing composition was produced based on the procedure of Synthesis Example 1, and various copolymerized polycarbonate diols were obtained by thin film distillation. Ta. The produced copolycarbonate diol is referred to as "PCD6". The evaluation results of PCD6 are shown in Table 1.

[Synthesis Example 8: Synthesis of PCD8]
1,4BG, NPG, and DPC were charged in a predetermined molar ratio, and other than that, a copolymerized polycarbonate diol-containing composition was produced based on the procedure of Synthesis Example 1, and various copolymerized polycarbonate diols were obtained by thin film distillation. Ta. The produced copolymerized polycarbonate diol is referred to as "PCD8". The evaluation results of PCD8 are shown in Table 1.

[Manufacture and evaluation of thermoplastic polyurethane resin elastomer]
[Example 1]
A thermoplastic polyurethane resin elastomer was synthesized by a one-shot method according to the following procedure.
The polycarbonate diol (PCD2) produced in Synthesis Example 4 was placed in a 1 L tin can, and the polycarbonate diol was heated to 100° C. while stirring using a three-one motor. Next, while stirring, a predetermined amount of 1,4-BG (manufactured by Mitsubishi Chemical Tosoh Corporation) as a difunctional aliphatic alcohol was added and mixed uniformly. To the obtained mixture, 4,4'-diphenylmethane diisocyanate (trade name: Monomeric MDI (Millionate MT), manufactured by Tosoh Corporation) melted at 70°C was added as a bifunctional aromatic isocyanate compound, and the mixture was uniformly mixed. Stir and mix. The obtained liquid mixture was poured into a mold on a hot plate whose surface temperature was controlled at 100° C. and cured for 30 minutes. The cured product obtained by cast polymerization was further heat-treated at 100° C. for 15 hours to complete the polymerization, and a cured product of thermoplastic polyurethane resin elastomer was obtained.
The composition ratio of the raw materials subjected to cast polymerization was set to [MDI]:[1,4-BG]:[PCD2]=3.50:2.33:1.00 (molar ratio). The content of the structural unit (III) in the thermoplastic polyurethane resin elastomer calculated from this composition ratio is 14.7 mol%. In addition, the NCO/OH equivalent ratio of the isocyanate group equivalent of the bifunctional aromatic isocyanate compound to the sum of the hydroxyl group equivalent of the difunctional aliphatic alcohol and the hydroxyl group equivalent of the polycarbonate diol was set to 1.05 ([MDI]/([ 1,4-BG]+[PCD2])=1.05).
The obtained cured product was pulverized using a pulverizer to obtain flakes. Next, the obtained flakes were dried at 80° C. for 12 hours and then put into an injection molding machine to obtain a molded sheet measuring 120 mm long x 120 mm wide x 2 mm thick. The obtained molded sheet was heat-treated at 100° C. for 24 hours, and was used as a test sample for evaluation. The evaluation results of this test sample are shown in Table 1.

[Examples 2 to 5, Comparative Examples 1 to 3]
A thermoplastic polyurethane resin elastomer was produced by the same procedure as in Example 1, except that the type of copolymerized polycarbonate diol was changed as shown in Table 1, and a test sample for evaluation was obtained. Table 1 shows the evaluation results of the test samples.

For PCD2 to PCD6 used in Examples 1 to 5, no endothermic peak was observed, or an endothermic peak was observed but the melting enthalpy was 5.0 J/g or less, so PCD2 to PCD6 used in Examples 1 to 5 were amorphous or low. It was crystalline. The obtained thermoplastic polyurethane resin elastomer had excellent injection moldability, and the obtained molded sheet had excellent mechanical properties and transparency.

PCD1 used in Comparative Example 1 had a large enthalpy of fusion and high crystallinity. The obtained thermoplastic polyurethane resin elastomer sheet had insufficient mechanical properties.

PCD7 and PCD8 used in Comparative Examples 2 and 3 were amorphous. The obtained thermoplastic polyurethane resin elastomer sheet had insufficient transparency and moldability, and was cloudy. This is presumably because PCD7 and PCD8 have low reactivity as polyols due to the high copolymerization ratio of neopentyl glycol, resulting in different higher-order structures of the obtained thermoplastic polyurethane resin elastomers.

Claims (10)

A structural unit (I) derived from a difunctional aromatic isocyanate compound, a structural unit (II) derived from a difunctional aliphatic alcohol with a number average molecular weight of less than 300, and a number average molecular weight of 1000 or more determined from the hydroxyl value. A thermoplastic polyurethane resin elastomer having a structural unit (III) derived from a polycarbonate diol having a molecular weight of 5,000 or less,
The structural unit (III) is a repeating unit (A) represented by the following formula (A) and a repeating unit (B) represented by the following formula (B), (A):(B)=3:97 Containing within a molar ratio of ~35:65,
The content ratio of the structural unit (III) in the thermoplastic polyurethane resin elastomer is based on 100 mol% of the total molar amount of the structural unit (I), the structural unit (II), and the structural unit (III), 5 mol% or more and 45 mol% or less,
under conditions such that the equivalent ratio of the isocyanate group equivalent of the bifunctional aromatic isocyanate compound to the sum of the hydroxyl equivalent of the difunctional aliphatic alcohol and the hydroxyl equivalent of the polycarbonate diol is within the range of 0.98 or more and 1.20 or less. , a thermoplastic polyurethane resin elastomer obtained by reacting the difunctional aliphatic alcohol, the polycarbonate diol, and the difunctional aromatic isocyanate compound.

[The above formula (A) represents a structural unit derived from a transesterification product of a side chain aliphatic carbon hydrogen dihydroxy compound and a carbonate ester. R ¹ and R ² are each independently an alkyl group having 1 to 4 carbon atoms, and within the above range of carbon atoms, an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, or a substituent containing these atoms. May have. ]

[The above formula (B) represents a structural unit derived from a transesterification product of a linear aliphatic hydrocarbon dihydroxy compound and a carbonate ester. R ³ represents a straight chain aliphatic hydrocarbon group having 3 or 4 carbon atoms. ] The thermoplastic polyurethane resin elastomer according to claim 1, wherein the repeating unit (A) has a structural unit derived from a transesterification product of neopentyl glycol and carbonate ester. Claim 1, wherein in the structural unit (III), the molar ratio of the repeating unit (A) and the repeating unit (B) is within the range of (A):(B) = 4:96 to 29:71. The thermoplastic polyurethane resin elastomer described in . The thermoplastic polyurethane resin elastomer according to claim 1, which has a total light transmittance of 85% or more as measured in accordance with JIS K7361-1. The thermoplastic polyurethane resin elastomer according to claim 1, having a tensile strength of 55 MPa or more as measured in accordance with ISO 037-02. The thermoplastic polyurethane resin elastomer according to claim 1, which can be injection molded in a molding cycle of 70 seconds or less. The thermoplastic polyurethane resin elastomer according to claim 1, wherein the linear aliphatic hydrocarbon dihydroxy compound is 1,4-butanediol. The bifunctional aromatic isocyanate compound is selected from 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, and 3,3'-dimethyl-4,4'-biphenylene diisocyanate. The thermoplastic polyurethane resin elastomer according to claim 1, which is at least one selected from the group consisting of: The difunctional aliphatic alcohol is at least one selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. , the thermoplastic polyurethane resin elastomer according to claim 1. A molded article comprising the thermoplastic polyurethane resin elastomer according to any one of claims 1 to 9.