Polycarbonate diol, method for producing polycarbonate diol, and polyurethane

Abstract

Provided is a polycarbonate diol containing structural units (1) represented by general formula (I) and structural units (2) represented by general formula (II). (In general formula (I), R represents a C2 to 20 hydrocarbon group optionally having a substituent or a hetero atom.) (In general formula (II), m is an integer of 2 to 20. R2 represents an optionally substituted C1 to 20 alkyl group or a hydrogen atom.)

Description

[Technical Field]

[0001] The present invention relates to a polycarbonate diol and a method for producing the polycarbonate diol. Furthermore, the present invention relates to a polyurethane obtained by using the polycarbonate diol. [Background technology]

[0002] As polyurethanes produced on an industrial scale, polycarbonate-type polyurethanes using polycarbonate diol as a raw material for the soft segment part have been proposed (Non-Patent Document 1). Polycarbonate-type polyurethanes are considered to be the most durable grades in terms of heat resistance and hydrolysis resistance, and are widely used in durable films, artificial leather for automobiles, (water-based) paints, and adhesives. In the above applications, polyurethanes are required that are excellent in mechanical properties, have reduced variations in mechanical properties from the viewpoint of uniform quality, and maintain good chemical resistance.

[0003] In polycarbonate diols currently widely available on the market as raw materials for polycarbonate-type polyurethanes, linear aliphatic diols having 3 to 6 carbon atoms, such as 1,6-hexanediol, are mainly used as the dihydroxy compound raw material.

[0004] Furthermore, in order to improve the flexibility, crystallinity, strength, etc. of polyurethane, an aliphatic polycarbonate diol using 1,6-hexanediol in combination with other dihydroxy compounds has been proposed.

[0005] For example, Patent Document 1 discloses a technique for improving the flexibility and elastic recovery of polyurethane obtained by combining 1,6-hexanediol and 1,5-pentanediol as dihydroxy compounds, which are raw materials for polycarbonate diol. Patent Document 2 discloses a technique for improving the oil resistance, heat resistance, and cold resistance of the resulting polyurethane by combining 1,6-hexanediol and 1,4-butanediol as the dihydroxy compound that is a raw material of the polycarbonate diol. Patent Document 3 discloses a technique for improving the strength and hardness of the resulting polyurethane by combining 1,6-hexanediol and isosorbide as the dihydroxy compound that is a raw material of the polycarbonate diol. Patent Document 4 discloses a technique for suppressing the coloring of the resulting polycarbonate and moderately improving the reactivity with a polyisocyanate compound by including a tertiary amino alcohol in a polycarbonate diol composition, thereby improving the efficiency of polyurethane production.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, Patent Documents 1 to 4 do not mention at all that the amine compounds contained in the linear aliphatic diols having 2 to 20 carbon atoms such as 1,6 - hexanediol, which are raw materials, can maintain good chemical resistance of the polyurethane obtained using the produced polycarbonate diol while affecting the mechanical properties and the variation in the mechanical strength. Therefore, conventionally, in terms of the production efficiency of polycarbonate diol when using linear aliphatic diols having 2 to 20 carbon atoms such as 1,6 - hexanediol as the raw material dihydroxy compound, and the costs and quality in industrially producing and using polyurethanes using such polycarbonate diol, satisfactory results have not been obtained.

[0009] The present invention has been made in view of the above problems. An object of the present invention is to provide a polycarbonate diol which, when used as a polyurethane raw material, contains a structural unit derived from a linear aliphatic diol having 2 to 20 carbon atoms such as 1,6 - hexanediol, has excellent mechanical properties of the resulting polyurethane, suppresses the variation in the mechanical properties from the viewpoint of quality uniformity, and further maintains good chemical resistance.

Means for Solving the Problems

[0010] As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by incorporating a structural unit derived from an amine into the polycarbonate diol.

[0011] The present invention has been achieved based on such findings, and the gist is as follows.

[0012] [1] A polycarbonate diol containing a structural unit (1) represented by the following general formula (I) and a structural unit (2) represented by the following general formula (II).

[0013]

Chemical formula

[0014] (In the general formula (I) above, R represents a hydrocarbon group having 2 to 20 carbon atoms, which may have a substituent or a hetero atom.)

[0015]

Chemical formula

[0016] (In the general formula (II) above, m is an integer of 2 to 20. R 2 represents an alkyl group having 1 to 20 carbon atoms or a hydrogen atom, which may have a substituent.)

[0017] [2] The polycarbonate diol according to [1], wherein the structural unit (1) contains a structural unit (1a) represented by the following general formula (Ia).

[0018]

Chemical formula

[0019] (In the general formula (Ia) above, n is an integer of 2 to 20.)

[0020] [3] The polycarbonate diol according to [1] or [2], wherein the structural unit (2) is a structural unit derived from an amine having an aliphatic hydrocarbon group having 2 to 20 carbon atoms, which may have a substituent.

[0021] [4] The polycarbonate diol according to any one of [1] to [3], wherein the structural unit (2) contains one or more amino groups and one or more functional groups, and the functional group is a structural unit derived from at least one amine selected from the group consisting of a hydroxyl group, a carboxyl group, a formyl group, and an amino group.

[0022] [5] The polycarbonate diol according to any one of [1] to [4], wherein the structural unit (2) contains a structural unit derived from an amine represented by the following general formula (II-1).

[0023]

Chem.

[0024] (In the general formula (II-1) above, R 1 -〔X〕 r represents an alkyl group having r substituents X, which may have substituents other than X, and having 2 to 20 carbon atoms. X represents any one of a hydroxyl group, a carboxyl group, a formyl group, and an amino group. r is an integer from 1 to 6. R 2 represents an alkyl group having 1 to 20 carbon atoms or a hydrogen atom, which may have substituents.)

[0025] [6] The polycarbonate diol according to any one of [1] to [5], wherein the structural unit (2) is a structural unit derived from at least one amine selected from a primary amine (2-1) and a secondary amine (2-2).

[0026] [7] The polycarbonate diol according to [5] or [6], wherein the structural unit (2) contains a structural unit derived from at least one amine selected from 6-amino-1-hexanol, 6-methylamino-1-hexanol, and 6-ethylamino-1-hexanol.

[0027] [8] The polycarbonate diol according to any one of [1] to [7], wherein the content of the structural unit (2) contained in the polycarbonate diol is 1 mass ppm or more in terms of nitrogen atom relative to the total mass of the polycarbonate diol.

[0028] [9] The polycarbonate diol according to any one of [1] to [8], wherein the content of the structural unit (2) contained in the polycarbonate diol is 1200 mass ppm or less in terms of nitrogen atom relative to the total mass of the polycarbonate diol.

[0029]

[10] The polycarbonate diol according to [9], wherein the content of the structural unit (2) contained in the polycarbonate diol is 80 ppm by mass or less in terms of nitrogen atom with respect to the total mass of the polycarbonate diol.

[0030]

[11] The polycarbonate diol according to

[10] , wherein the polycarbonate diol further contains an aldehyde.

[0031]

[12] The polycarbonate diol according to any one of [1] to

[11] , wherein the number average molecular weight (Mn) of the polycarbonate diol is 250 or more and 5000 or less.

[0032]

[13] A method for producing a polycarbonate diol, comprising polycondensing a dihydroxy compound composition containing an amine and a dihydroxy compound (1) represented by the following general formula (I-1) and a carbonate compound by a transesterification reaction in the presence of a catalyst to obtain a polycarbonate diol containing a structural unit (2) represented by the following general formula (II).

[0033]

Chemical formula

[0034] (In the general formula (I-1), R is a hydrocarbon group having 2 to 20 carbon atoms which may have a substituent or a hetero atom.)

[0035]

Chemical formula

[0036] (In the above general formula (II), m is an integer of 2 to 20. R 2 represents an alkyl group having 1 to 20 carbon atoms or a hydrogen atom which may have a substituent.)

[0037]

[14] The method for producing a polycarbonate diol according to

[13] , wherein the polycarbonate diol contains a structural unit (1) represented by the following general formula (I):

[0038] [ka]

[0039] (In the above general formula (I), R is a hydrocarbon group having 2 to 20 carbon atoms, which may have a substituent or a heteroatom.)

[0040]

[15] The method for producing a polycarbonate diol according to

[13] or

[14] , wherein the amine is an amine having an aliphatic hydrocarbon group having 2 to 20 carbon atoms which may have a substituent.

[0041]

[16] The method for producing a polycarbonate diol according to any one of

[13] to

[15] , wherein the amine contains one or more amino groups and one or more functional groups, and the functional group is at least one selected from the group consisting of a hydroxyl group, a carboxyl group, a formyl group, and an amino group.

[0042]

[17] The method for producing a polycarbonate diol according to any one of

[13] to

[16] , wherein the amine includes an amine represented by the following general formula (II-1):

[0043] [ka]

[0044] (In the above general formula (II-1), R 1 -〔X〕 r represents an alkyl group having 2 to 20 carbon atoms and having r substituents X, which may have substituents other than X. X represents a hydroxyl group, a carboxyl group, a formyl group, or an amino group. r is an integer of 1 to 6. R 2 represents an alkyl group having 1 to 20 carbon atoms, which may have a substituent, or a hydrogen atom.

[0045]

[18] The method for producing a polycarbonate diol according to any one of

[13] to

[17] , wherein the amine contains at least one selected from a primary amine (2-1) and a secondary amine (2-2).

[0046]

[19] The method for producing a polycarbonate diol according to

[17] or

[18] , wherein the amine contains at least one selected from 6-amino-1-hexanol, 6-methylamino-1-hexanol, and 6-ethylamino-1-hexanol.

[0047]

[20] The method for producing a polycarbonate diol according to any one of

[13] to

[19] , wherein the content of the amine in the dihydroxy compound composition is 1 mass ppm or more in terms of nitrogen atom relative to the total mass of the dihydroxy compound composition.

[0048]

[21] The method for producing a polycarbonate diol according to any one of

[13] to

[20] , wherein the content of the amine in the dihydroxy compound composition is 1500 mass ppm or less in terms of nitrogen atom relative to the total mass of the dihydroxy compound composition.

[0049]

[22] The method for producing a polycarbonate diol according to

[21] , wherein the content of the amine in the dihydroxy compound composition is 100 mass ppm or less in terms of nitrogen atom relative to the total mass of the dihydroxy compound composition.

[0050]

[23] The method for producing a polycarbonate diol according to

[22] , wherein the dihydroxy compound composition further contains an aldehyde.

[0051]

[24] The method for producing a polycarbonate diol according to any one of

[13] to

[23] , wherein the content of the structural unit (2) contained in the polycarbonate diol is 1 ppm or more in terms of nitrogen atom relative to the total mass of the polycarbonate diol.

[0052]

[25] The method for producing a polycarbonate diol according to any one of

[13] to

[24] , wherein the content of the structural unit (2) contained in the polycarbonate diol is 1200 mass ppm or less in terms of nitrogen atom with respect to the total mass of the polycarbonate diol.

[0053]

[26] The method for producing a polycarbonate diol according to

[25] , wherein the content of the structural unit (2) contained in the polycarbonate diol is 80 mass ppm or less in terms of nitrogen atom with respect to the total mass of the polycarbonate diol.

[0054]

[27] The method for producing a polycarbonate diol according to

[26] , wherein the polycarbonate diol further contains an aldehyde.

[0055]

[28] A polyurethane obtained by using the polycarbonate diol according to any one of [1] to

[12] .

[0056]

[29] The polyurethane according to

[28] , which is used in any one selected from the group consisting of an active energy ray curable polymer composition, artificial leather, synthetic leather, paint, coating agent, elastic fiber, adhesive, and adhesive.

Advantages of the Invention

[0057] According to the present invention, there is provided a polycarbonate diol capable of stably producing a high-quality polyurethane having excellent mechanical properties, suppressed variation in the mechanical properties, and maintained good chemical resistance.

Modes for Carrying Out the Invention

[0058] Hereinafter, the embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.

[0059] In this specification, the "structural unit" refers to a unit derived from the raw material compound, which is formed by the polymerization of the raw material compound used in the production of the polycarbonate diol, and represents a partial structure sandwiched between any linking groups in the obtained polymer. The structural unit also includes a partial structure in which one end is a linking group and the other end is a polymerization reactive group at the terminal portion of the polymer. The structural unit may be a unit directly formed by a polymerization reaction, or a unit in which a part of the unit is converted into another structure by treating the obtained polymer. In this specification, the "repeating unit" has the same meaning as the "structural unit".

[0060] In this specification, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value, unless otherwise specified. For example, "A~B" means A or more and B or less.

[0061] In this specification, "including A or B" means, unless otherwise specified, "including A", "including B", and "including both A and B".

[0062] In this specification, "mass%" indicates the content ratio of a predetermined component contained in the total amount of 100 mass%. In this specification, "mass%" and "weight%", "mass ppm" and "weight ppm", and "parts by mass" and "parts by weight" are synonymous, respectively. Also, when simply described as "ppm", it means "weight ppm".

[0063] In this specification, the "obtained polyurethane" refers to the polyurethane produced using the polycarbonate diol of the present invention.

[0064] [Polycarbonate diol] The polycarbonate diol of the present invention is a polycarbonate diol containing a structural unit (1) represented by the following general formula (I) and a structural unit (2) represented by the following general formula (II) (hereinafter, may be referred to as "the polycarbonate diol of the present invention").

[0065]

Chem.

[0066] (In the above general formula (I), R represents a hydrocarbon group having 2 to 20 carbon atoms which may have a substituent or a heteroatom.)

[0067]

Chem.

[0068] (In the above general formula (II), m is an integer of 2 to 20. R 2 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms which may have a substituent.)

[0069] By including the said structural unit (2), the polycarbonate diol of the present invention makes the mechanical strength of the polyurethane obtained using this polycarbonate diol excellent, and also makes it possible to stably produce a high-quality polyurethane in which the variation in the said mechanical strength is suppressed and the chemical resistance is maintained well.)

[0070] The polycarbonate diol of the present invention can include a structural unit represented by the following general formula (IIIa) or the following general formula (IIIb) as a terminal structure.)

[0071]

Chem.

[0072] (In the above general formula (IIIa), m is an integer of 2 to 20. R 2 is synonymous with R in the said formula (II), and represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms which may have a substituent.) 2

[0073]

Chem.

[0074] (In the general formula (IIIb), m is an integer of 2 to 20. R 2 is synonymous with R in the formula (II), and represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms which may have a substituent.) 2

[0075] In addition, since the polycarbonate diol of the present invention contains the structural unit (1), the mechanical properties and chemical resistance of the polyurethane obtained using this polycarbonate diol are improved.

[0076] Furthermore, the polycarbonate diol of the present invention can contain, within a range not impairing the effects of the present invention, a structural unit (3) derived from a dihydroxy compound (3) other than the compound (1) described later, if necessary.

[0077] (Molecular weight of polycarbonate diol) The lower limit of the number average molecular weight (Mn) of the polycarbonate diol of the present invention is not particularly limited, and from the viewpoint of obtaining good mechanical properties of the resulting polyurethane, 250 or more is preferable, 300 or more is more preferable, and 400 or more is even more preferable. On the other hand, the upper limit of the number average molecular weight (Mn) is not particularly limited, and from the viewpoint of suppressing the viscosity of the polycarbonate diol of the present invention to a certain extent and maintaining good handleability, or maintaining good chemical resistance of the resulting polyurethane, 5000 or less is preferable, 4000 or less is more preferable, and 3000 or less is even more preferable. The above upper and lower limits can be arbitrarily combined. For example, the number average molecular weight (Mn) of the polycarbonate diol in the present invention is preferably 250 or more and 5000 or less, more preferably 300 or more and 4000 or less, and even more preferably 400 or more and 3000 or less. The number average molecular weight (Mn) is the molecular weight calculated from the hydroxyl value, and the measurement conditions are as described in the examples below.

[0078] (Structural unit (1)) The above structural unit (1) is a structural unit represented by the following general formula (I) contained in the structure of the polycarbonate diol of the present invention.

[0079]

Chemical formula

[0080] In the polycarbonate diol of the present invention, as the structural unit (1), a structural unit derived from a dihydroxy compound (1) (also simply referred to as "compound (1)" in this specification) represented by the following general formula (I-1) can be used.

[0081]

Chemical formula

[0082] The lower limit of the content ratio of the structural unit (1) in the polycarbonate diol of the present invention is not particularly limited. From the viewpoint of obtaining good mechanical properties and chemical resistance of the resulting polyurethane, it is preferably 40% by mass or more, more preferably 60% by mass or more, further preferably 75% by mass or more, and particularly preferably 80% by mass or more based on 100% by mass of the total mass of the polycarbonate diol. On the other hand, the upper limit of the content ratio of the structural unit (1) is not particularly limited, and it may correspond to 100% by mass of the mass other than the structural unit (2) in the polycarbonate diol of the present invention, or may be less than 100% by mass. Alternatively, from the viewpoint of maintaining good chemical resistance of the resulting polyurethane, it is more preferably 98% by mass or less, further preferably 95% by mass or less, and particularly preferably 90% by mass or less based on 100% by mass of the total mass of the polycarbonate diol. The above upper and lower limits can be arbitrarily combined. For example, the content ratio of the structural unit (1) in the polycarbonate diol of the present invention is preferably 40% by mass or more and less than 100% by mass, more preferably 60% by mass or more and 98% by mass or less, still more preferably 75% by mass or more and 95% by mass or less, and particularly preferably 80% by mass or more and 90% by mass or less, based on 100% by mass of the total mass of the polycarbonate diol.

[0083] In the polycarbonate diol of the present invention, from the viewpoint of better mechanical properties and chemical resistance of the obtained polyurethane, the structural unit (1) preferably contains a structural unit represented by the following general formula (Ia).

[0084] [Chemical formula]

[0085] (In the above general formula (Ia), n is an integer of 2 to 20.)

[0086] In the general formula (Ia), n is an integer of 2 to 20, preferably 3 to 10, more preferably 3 to 6, and still more preferably 4 to 6, from the viewpoint of better mechanical properties and chemical resistance of the obtained polyurethane.

[0087] In the polycarbonate diol of the present invention, as the structural unit represented by the general formula (Ia), a structural unit derived from a compound represented by the following general formula (Ia-1) can be used.

[0088] [Chemical formula]

[0089] (In the above general formula (Ia-1), n is an integer of 2 to 20.)

[0090] The compound represented by the formula (Ia-1) is not particularly limited, and known dihydroxy compounds used as raw materials for polycarbonate diol can be appropriately selected and used. Examples of the compound represented by the formula (Ia-1) include 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-eicosanediol, etc., and those skilled in the art can appropriately select them according to the use of polycarbonate diol, manufacturing conditions, etc. For example, from the viewpoint of excellent balance of flexibility, low-temperature properties, and chemical resistance of the obtained polyurethane, at least one compound selected from the group consisting of 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,10-decanediol, preferably at least one compound selected from the group consisting of 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol can be used. These compounds may be used alone or in combination of two or more.

[0091] In the polycarbonate diol of the present invention, from the viewpoint of better mechanical properties and chemical resistance of the obtained polyurethane, the structural unit (1) may contain a structural unit represented by the following formula (Ib).

[0092]

Chemical formula

[0093] In the polycarbonate diol of the present invention, as the structural unit represented by the formula (Ib), a structural unit derived from a compound represented by the following formula (Ib-1), that is, 1,6-hexanediol can be used.

[0094] [ka]

[0095] In such a case, the content ratio of the structural unit represented by the general formula (Ia) and the content ratio of the structural unit represented by the formula (Ib) contained in the structural unit (1) are not particularly limited. The content ratios of the structural units represented by the general formula (Ia) and the formula (Ib) contained in the structural unit (1) are preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, and particularly preferably 70% by mass or more, relative to 100% of the total mass of the structural unit (1), from the viewpoint of improving the handleability of the polycarbonate diol and the flexibility and low-temperature properties of the resulting polyurethane. This content ratio may be 90% by mass or more. On the other hand, the upper limit of the content ratio of the structural unit represented by the general formula (Ia) and the content ratio of the structural unit represented by the formula (Ib) are not particularly limited, and may be 100% by mass or less, or may be 99% by mass or less, relative to 100% of the total mass of the structural unit (1).

[0096] In the polycarbonate diol of the present invention, the compound (1) derived from a fossil fuel can be used alone as the compound (1). Alternatively, the polycarbonate diol of the present invention can use a compound (1) containing a compound (1) derived from a biomaterial as the compound (1). Specifically, the Sustainable Development Goals (SDGs) can be achieved by using a single compound (1) derived from a biomaterial, or a mixture containing a compound (1) derived from a biomaterial and a compound (1) derived from a fossil fuel. The compound (1) derived from biomaterials is a compound (1) derived from non-edible biomass and / or non-fossil fuels.

[0097] In the present invention, non-edible biomass refers to resources made from non-edible grasses and trees. Specifically, it includes cellulose, hemicellulose, lignin, etc. obtained from woody biomass such as coniferous and broad-leaved trees, and bioethanol, biodiesel, waste oil derived from plants, etc. obtained from herbaceous biomass such as corn and sugarcane stems, and soybeans and rapeseed. However, it is not limited to these. In the present invention, non-fossil fuel refers to, for example, hydrogen, or organic substances derived from animals and plants that do not originate from fossil fuels or non-edible biomass. Specifically, it includes methane, sugar ethanol, etc. obtained from firewood, charcoal, dried livestock manure, etc. However, it is not limited to these.

[0098] In the present invention, the fossil fuel-derived compound (1) refers to at least one selected from petroleum-derived compound (1), coal-derived compound (1), and natural gas-derived compound (1).

[0099] (Structural unit (2)) The above-mentioned structural unit (2) is a structural unit represented by the following general formula (II) contained in the structure of the polycarbonate diol of the present invention.

[0100] [Chemical formula]

[0101] (In the above general formula (II), m is an integer from 2 to 20. R 2 represents an alkyl group having 1 to 20 carbon atoms or a hydrogen atom, which may have a substituent.)

[0102] In the polycarbonate diol of the present invention, the structural unit (2) is not particularly limited. As a first embodiment, from the viewpoint of better mechanical properties of the obtained polyurethane and better suppression of variations in mechanical properties, structural units derived from amines having an aliphatic hydrocarbon group having 2 to 20 carbon atoms, which may have a substituent, can be mentioned.

[0103] In the polycarbonate diol of the present invention, the structural unit (2) is not particularly limited, but as a second embodiment, from the viewpoint of improving the mechanical properties of the obtained polyurethane and suppressing variations in the mechanical properties, an example is a structural unit containing one or more amino groups and one or more functional groups, wherein the functional group is derived from at least one kind of amine selected from the group consisting of a hydroxyl group, a carboxyl group, a formyl group, and an amino group.

[0104] In the polycarbonate diol of the present invention, the structural unit (2) is not particularly limited, but as a third embodiment, from the viewpoint of improving the mechanical properties of the obtained polyurethane and suppressing the variation in the mechanical properties, a structural unit derived from an amine represented by the following general formula (II-1) can be mentioned.

[0105] [ka]

[0106] (In the above general formula (II-1), R 1 -〔X〕 r represents an alkyl group having 2 to 20 carbon atoms and having r substituents X, which may have substituents other than X. X represents a hydroxyl group, a carboxyl group, a formyl group, or an amino group. r is an integer of 1 to 6. R 2 represents an alkyl group having 1 to 20 carbon atoms, which may have a substituent, or a hydrogen atom.

[0107] In the above general formula (II-1), NHR 2 and X react with the carbonate bond or hydroxyl group of the polycarbonate diol, or with the isocyanate compound used as a raw material for polyurethane. If an excessive number of substituents X are present, a crosslinked structure is formed in the polyurethane during the polymerization process in producing the polyurethane, causing gelation and impairing polymerization stability. Therefore, r, which represents the number of substituents X, is preferably 1 or 2, and more preferably 1. R 1The carbon number of is 2 to 20. From the viewpoint of good mechanical properties of the polyurethane obtained using the polycarbonate diol of the present invention, R 1 The carbon number of is preferably 3 to 10, more preferably 3 to 6, and even more preferably 4 to 6. R 2 is an alkyl group having 1 to 20 carbon atoms or a hydrogen atom. From the viewpoint of good mechanical properties of the polyurethane obtained using the polycarbonate diol of the present invention, R 2 is preferably an alkyl group having 3 to 10 carbon atoms or a hydrogen atom, more preferably an alkyl group having 3 to 6 carbon atoms or a hydrogen atom, and even more preferably an alkyl group having 4 to 6 carbon atoms or a hydrogen atom.

[0108] In the polycarbonate diol of the present invention, the structural unit (2) is not particularly limited. As a fourth embodiment, from the viewpoint of better mechanical properties of the obtained polyurethane and better suppression of variations in mechanical properties, a structural unit derived from at least one amine selected from primary amine (2-1) and secondary amine (2-2) can be mentioned. The primary amine (2-1) and secondary amine (2-2) in the present invention are not particularly limited, and known amine compounds can be employed. The primary amine (2-1) and secondary amine (2-2) may be one kind or two or more kinds.

[0109] The primary amine (2-1) and secondary amine (2-2) are not particularly limited. For example, amine compounds in which some or all of the hydroxy groups of the compound (1) are replaced with amino groups can be mentioned.

[0110] The types of the primary amine (2-1) and secondary amine (2-2) in the present invention are not particularly limited. For example, in the amine represented by the general formula (II-1), the following can be mentioned. R 1 When is a propylene group having 3 carbon atoms, primary amine compounds such as 3-amino-1-propanol, secondary amine compounds such as 3-methylamino-1-propanol; R 1 When R is a butylene group having 4 carbon atoms, primary amine compounds such as 4-amino-1-butanol and secondary amine compounds such as 4-methylamino-1-butanol; R 1 When R is a pentylene group having 5 carbon atoms, primary amine compounds such as 5-amino-1-pentanol and secondary amine compounds such as 5-methylamino-1-pentanol; R 1 When R is a hexylene group having 6 carbon atoms, primary amine compounds such as 6-amino-1-hexanol and secondary amine compounds such as 6-methylamino-1-hexanol and 6-ethylamino-1-hexanol: Among them, at least one selected from 6-amino-1-hexanol, 6-methylamino-1-hexanol and 6-ethylamino-1-hexanol is preferable.

[0111] When the primary amine (2-1) and the secondary amine (2-2) are amine compounds in which some or all of the hydroxy groups of the compound (1) are replaced with amino groups, examples of the amine compounds include those described below in the general formula (Ia-1). When n = 3, primary amine compounds such as 3-amino-1-propanol and 1,3-diaminopropane, and secondary amine compounds such as 3-methylamino-1-propanol; When n = 4, primary amine compounds such as 4-amino-1-butanol and 1,4-diaminobutane, and secondary amine compounds such as 4-methylamino-1-butanol; When n = 5, primary amine compounds such as 5-amino-1-pentanol and 1,5-diaminopentane, and secondary amine compounds such as 5-methylamino-1-pentanol; When n = 6 (the compound represented by the general formula (Ib-1)), primary amine compounds such as 6-amino-1-hexanol and 1,6-diaminohexane, and secondary amine compounds such as 6-methylamino-1-hexanol and 6-ethylamino-1-hexanol:

[0112] Alternatively, as the primary amine (2-1) and the secondary amine (2-2), an alkylamine having an amino group in the molecule and no functional group other than the amino group can be mentioned. Examples of the alkylamine include at least one selected from the group consisting of monoalkylamine and dialkylamine. More specifically, examples of the alkylamine include diethylamine, propylamine, dipropylamine, butylamine, dibutylamine, amylamine, diamylamine, hexylamine, dihexylamine, heptylamine, diheptylamine, octylamine, dioctylamine, nonylamine, dinonylamine, decylamine, didecylamine, dodecylamine, didodecylamine, and the like. Also, structural isomers and derivatives of these compounds can be mentioned. These compounds may be used alone or in combination of two or more.

[0113] Among the above-mentioned primary amine (2-1) and secondary amine (2-2), as the structural unit (2) in the fourth embodiment of the polycarbonate diol of the present invention, a structural unit derived from at least one amine selected from 6-amino-1-hexanol, 6-methylamino-1-hexanol, and 6-ethylamino-1-hexanol is preferable.

[0114] When the compound (1) is derived from a bio-based material, particularly glucose, xylose, etc., which are non-edible biomass, the above-mentioned primary amine (2-1) and secondary amine (2-2) may be included depending on the origin. Therefore, by controlling the content ratio of the primary amine (2-1) and secondary amine (2-2) in the compound (1) to produce a polycarbonate diol, or by controlling the content ratio of the structural unit derived from the amine contained in the polycarbonate diol produced using the compound (1), the effects of the present invention described above can be obtained.

[0115] For example, as the compound represented by the formula (Ib-1), the polycarbonate diol in the present invention can use a single substance of 1,6-hexanediol derived from fossil fuel. Alternatively, as the compound represented by the formula (Ib-1), the polycarbonate diol in the present invention can use 1,6-hexanediol containing 1,6-hexanediol derived from bio-based raw materials. Specifically, a single substance of 1,6-hexanediol derived from bio-based raw materials or a mixture containing 1,6-hexanediol derived from bio-based raw materials and 1,6-hexanediol derived from fossil fuel can be used. Thereby, the achievement of sustainable development goals (SDGs) can be achieved. 1,6-Hexanediol derived from bio-based raw materials is 1,6-hexanediol derived from non-edible biomass and / or non-fossil fuel.

[0116] In addition, in the present invention, 1,6-hexanediol derived from fossil fuel refers to at least one selected from 1,6-hexanediol derived from petroleum, 1,6-hexanediol derived from coal, and 1,6-hexanediol derived from natural gas.

[0117] The above-mentioned 1,6-hexanediol derived from bio-based raw materials may contain primary or secondary amines such as 6-amino-1-hexanol and 6-methylamino-1-hexanol described above depending on its origin. Therefore, by controlling the content ratio of the primary or secondary amine in the 1,6-hexanediol to produce a polycarbonate diol or by controlling the content ratio of the primary or secondary amine in the polycarbonate diol produced using the 1,6-hexanediol, the effects of the present invention described above can be obtained.

[0118] The upper limit of the content of the structural unit (2) contained in the polycarbonate diol of the present invention is not particularly limited. From the viewpoints of suppressing the coloring of the polycarbonate diol and achieving a good color tone, having a good yield during the production of the polycarbonate diol, and further maintaining good mechanical properties and chemical resistance of the obtained polyurethane, the content of the structural unit (2) is preferably 1200 mass ppm or less in terms of nitrogen atom relative to the total mass of the polycarbonate diol. The higher the content of the structural unit (2), the more it acts as a coloring component in the polycarbonate diol, and the color tone of the polycarbonate diol is impaired. The upper limit of the content of the structural unit (2) is more preferably 1000 mass ppm or less, further preferably 900 mass ppm or less, particularly preferably 700 mass ppm or less, and especially preferably 500 mass ppm or less in terms of nitrogen atom. On the other hand, the lower limit of the content of the structural unit (2) is not particularly limited. From the viewpoint of economy for reducing the amine and moderately increasing the molecular weight distribution of the polyurethane obtained using the polycarbonate diol of the present invention to enhance the mechanical properties of the polyurethane and suppress the variation in the mechanical properties, in terms of nitrogen atom, it is preferably 1 mass ppm or more, more preferably 10 mass ppm or more, further preferably 50 mass ppm or more, particularly preferably 100 mass ppm or more, and especially preferably 150 mass ppm or more relative to the total mass of the polycarbonate diol. The above upper and lower limits can be arbitrarily combined. For example, the content of the amine in the polycarbonate diol of the present invention is preferably 1 mass ppm or more and 1200 mass ppm or less, more preferably 10 mass ppm or more and 1000 mass ppm or less, further preferably 50 mass ppm or more and 900 mass ppm or less, particularly preferably 100 mass ppm or more and 700 mass ppm or less, and especially preferably 150 mass ppm or more and 500 mass ppm or less in terms of nitrogen atom relative to the total mass of the polycarbonate diol.

[0119] In the polycarbonate diol of the present invention, when the upper limit of the content of the structural unit (2) contained in the polycarbonate diol is 80 mass ppm or less in terms of nitrogen atom relative to the total mass of the polycarbonate diol, the higher the content of the structural unit (2), the more the coloring of the polycarbonate diol can be suppressed and the color tone can be controlled well. The higher the content of the structural unit (2) contained in the polycarbonate diol is more than 80 mass ppm in terms of nitrogen atom, the more coloring components are by-produced due to the oxidation of the amine group in the structural unit (2), and the polycarbonate diol tends to be colored and the color tone is impaired. From the viewpoint of suppressing the coloring of the polycarbonate diol and making the color tone better, the upper limit of the content of the structural unit (2) in the polycarbonate diol is preferably 70 mass ppm or less, more preferably 60 mass ppm or less, still more preferably 50 mass ppm or less, and most preferably 40 mass ppm or less in terms of nitrogen atom. On the other hand, the lower limit of the content of the structural unit (2) in the polycarbonate diol is not particularly limited. However, from the viewpoint of economy for reducing the content of the structural unit (2), from the viewpoint of suppressing the coloring of the polycarbonate diol caused by the dihydroxy compound composition which is a raw material of the polycarbonate diol described later and the aldehyde contained in the polycarbonate diol and making the color tone good, from the viewpoint of appropriately increasing the molecular weight distribution of the polyurethane obtained by using the polycarbonate diol of the present invention to enhance the mechanical properties of the polyurethane and suppressing the variation of the mechanical properties, usually, it is preferably 0.1 mass ppm or more, more preferably 1 mass ppm or more, still more preferably 2 mass ppm or more, particularly preferably 5 mass ppm or more, and most preferably 10 mass ppm or more in terms of nitrogen atom relative to the total mass of the polycarbonate diol. The upper and lower limits can be combined arbitrarily. For example, when the content of the structural unit (2) contained in the polycarbonate diol is 80 mass ppm or less in terms of nitrogen atoms relative to the total mass of the polycarbonate diol, the content of the structural unit (2) is preferably 0.1 mass ppm or more and 80 mass ppm or less, more preferably 1 mass ppm or more and 70 mass ppm or less, still more preferably 2 mass ppm or more and 60 mass ppm or less, particularly preferably 5 mass ppm or more and 50 mass ppm or less, and most preferably 10 mass ppm or more and 40 mass ppm or less, in terms of nitrogen atoms relative to the total mass of the polycarbonate diol.

[0120] In the present invention, the content of the structural unit (2) in the polycarbonate diol is specifically the content measured by the method described in the examples below. In the polycarbonate diol of the present invention, the specific method for controlling the content of the structural unit (2) in the polycarbonate diol within the above-mentioned numerical range is not particularly limited, and a person skilled in the art can control it by appropriately optimizing the production conditions of the production method of the polycarbonate diol of the present invention described below based on well-known techniques.

[0121] <Aldehyde> When the content of the structural unit (2) in the polycarbonate diol of the present invention is 80 mass ppm or less in terms of nitrogen atoms, the higher the content of the structural unit (2), the more effectively aldehyde production can be suppressed, and therefore the more pronounced the coloration suppression effect of the polycarbonate diol of the present invention can be obtained. According to the studies of the present inventors, dihydroxy compound compositions, which are raw materials for polycarbonate diol, may contain aldehydes for the reasons described below. When producing polycarbonate diol using a dihydroxy compound composition containing such aldehydes, or when storing the obtained polycarbonate diol for a long period of time, the aldehydes generate radicals by heating or oxidation, and aldehyde groups, carboxylic acids, double bonds, etc. are produced in the dihydroxy compound or polycarbonate diol. As a result, it is presumed that a conjugated structure is formed in the structure of the polycarbonate diol, causing the polycarbonate diol to become colored. The structural unit (2) in the polycarbonate diol is presumed to be able to suppress the by-production of aldehyde and the generation of aldehyde radicals, thereby suppressing the coloration of the polycarbonate diol.

[0122] The aldehyde in the present invention is not particularly limited, and any known aldehyde compound or an aldehyde compound in which the hydroxy group of the compound (1) is replaced with an aldehyde group can be used. An aldehyde group may react with a hydroxy group to convert to an acetal group. Therefore, the aldehyde in the present invention also includes an acetal compound in which the aldehyde group of the aldehyde compound is replaced with an acetal group (hereinafter, sometimes simply referred to as "acetal"). That is, the content of aldehyde in the present invention means the total content of the aldehyde compound and the acetal which is its acetal modification product.

[0123] Examples of the acetal include (a) an acetal compound in which the aldehyde group of the aldehyde reacts with a hydroxy group to form an acetal group; (b) an acetal compound in which two molecules of a monohydroxy compound react with one aldehyde group of the aldehyde; (c) an acetal compound in which one molecule of a dihydroxy compound reacts with one aldehyde group of the aldehyde; and (d) a hemiacetal compound in which one molecule of a monohydroxy compound reacts with one aldehyde group of the aldehyde. The acetal may be one of these or may be two or more of them.

[0124] Furthermore, the aldehyde in the present invention includes both the aldehyde free in the polycarbonate diol of the present invention and the aldehyde bonded or associated with the polycarbonate diol in the polycarbonate diol or included as a part of the structure of the polycarbonate diol.

[0125] The form of the "aldehyde bonded or associated with the polycarbonate diol or included as a part of the structure of the polycarbonate diol" is not particularly limited. For example, a form in which a hydroxy group or an amino group contained in the aldehyde reacts to form a carbonate bond or a urethane bond in the polycarbonate diol can be mentioned.

[0126] The aldehyde is by-produced in the hydrogenation reaction step when producing the compound (1) by subjecting a carboxylic acid having 3 to 6 carbon atoms or an ester derivative of the carboxylic acid, which is a precursor of the compound (1), to a hydrogenation reaction.

[0127] The type of the "precursor of the compound (1)" is not particularly limited. For example, in the compound represented by the general formula (Ia-1), the following can be mentioned. When n = 3, malonic acid or a malonic acid ester; When n = 4, succinic acid or a succinic acid ester; When n = 5, glutaric acid or a glutaric acid ester; When n = 6 (compound represented by the formula (Ib-1)), adipic acid or an adipic acid ester:

[0128] In the production stage of the compound (1), as a method for increasing the amount of the by-product aldehyde, methods such as reducing the amount of the catalyst used in the hydrogenation reaction, shortening the residence time, and making the hydrogen pressure too low can be used. Conversely, as a method for reducing the aldehyde which is a by-product in the production stage of the compound (1), methods such as increasing the amount of catalyst used in the hydrogenation reaction, lengthening the residence time, or excessive hydrogen pressure can be used.

[0129] Since acetal requires a hydrogenation catalytic ability different from that of aldehyde, it is difficult to undergo a hydrogenation reaction with an aldehyde hydrogenation catalyst, and acetal may remain in the compound (1). In the production of the compound (1), usually, after the hydrogenation reaction step, the compound (1) is purified by distillation. Even in this distillation stage, acetal by-produced in the hydrogenation reaction step may decompose into aldehyde and mix into the purified compound (1). Also, aldehyde may react with a hydroxy group to form acetal and mix into the compound (1). Generally, aldehydes by-produced in the production process of dihydroxy compounds with a small number of carbon atoms can be separated relatively easily by distillation purification. However, when the boiling points of the compound (1) and aldehyde are close and it is difficult to separate them as acetal, aldehyde and acetal are likely to remain in the compound (1) even after distillation purification.

[0130] The types of aldehydes in the present invention are not particularly limited. For example, in the compound represented by the general formula (Ia-1), the following can be mentioned. When n = 3, monoaldehyde compounds such as 3-hydroxypropanal, dialdehyde compounds of malondialdehyde; When n = 4, monoaldehyde compounds such as 4-hydroxybutanal, dialdehyde compounds of succinaldehyde; When n = 5, monoaldehyde compounds such as 5-hydroxypentanal, dialdehyde compounds of glutaraldehyde; When n = 6 (compound represented by the formula (Ib-1)), monoaldehyde compounds such as 6-hydroxyhexanal, dialdehyde compounds such as adipaldehyde:

[0131] When the compound (1) is 1,6 - hexanediol and is derived from bio - raw materials, particularly glucose, xylose, etc. which are non - edible biomass, mono - aldehyde compounds such as 6 - hydroxyhexanal and adipaldehyde may be contained in the 1,6 - hexanediol.

[0132] <Content ratio of aldehyde> The content ratio of the aldehyde contained in the polycarbonate diol of the present invention refers to the content ratio of the aldehyde in the polycarbonate diol. When the polycarbonate diol contains the acetal, the content ratio of the aldehyde in the polycarbonate diol of the present invention refers to the total content ratio of the aldehyde and the acetal in the polycarbonate diol.

[0133] When the content of the structural unit (2) in the polycarbonate diol of the present invention is 80 mass ppm or less in terms of nitrogen atom, the lower limit of the content ratio of the aldehyde contained in the polycarbonate diol is not particularly limited. From the viewpoint of economy for reducing the aldehyde, the lower limit of the content ratio of the aldehyde is usually 1 mass ppm with respect to the total mass of the polycarbonate diol, preferably 10 mass ppm or more, more preferably 50 mass ppm or more, further preferably 100 mass ppm or more, and particularly preferably 170 mass ppm or more. On the other hand, the upper limit of the content ratio of the aldehyde is not particularly limited. From the viewpoint of effectively obtaining the coloring suppression effect by the structural unit (2), the upper limit of the content ratio of the aldehyde is usually 630 mass ppm or less with respect to the total mass of the polycarbonate diol, preferably 600 mass ppm or less, more preferably 500 mass ppm or less, further preferably 450 mass ppm or less, and particularly preferably 400 mass ppm or less. When the content of the structural unit (2) in the polycarbonate diol of the present invention is 80 mass ppm or less in terms of nitrogen atoms, for example, the content of the aldehyde contained in the polycarbonate diol of the present invention is usually 1 mass ppm or more and 630 mass ppm or less, preferably 10 mass ppm or more and 600 mass ppm or less, more preferably 50 mass ppm or more and 500 mass ppm or less, still more preferably 100 mass ppm or more and 450 mass ppm or less, and particularly preferably 170 mass ppm or more and 400 mass ppm or less, relative to the total mass of the polycarbonate diol.

[0134] As mentioned above, the aldehyde in the polycarbonate diol of the present invention includes both the aldehyde that is free in the polycarbonate diol of the present invention and the aldehyde that is bonded to or associated with the polycarbonate diol in the polycarbonate diol or that is included as part of the structure of the polycarbonate diol. When the aldehyde is contained free from the polycarbonate diol, the polycarbonate diol of the present invention is also called a polycarbonate diol composition containing the polycarbonate diol and the aldehyde. However, since the content of the free aldehyde in the polycarbonate diol of the present invention is a trace amount in the ppm by mass range as mentioned above, in the present invention, the polycarbonate diol containing the free aldehyde is also called "polycarbonate diol". The aldehyde content in the polycarbonate diol of the present invention is measured by the method described in the Examples section below.

[0135] In the polycarbonate diol of the present invention, the specific method for controlling the content ratio of the aldehyde in the polycarbonate diol within the above-mentioned numerical range is not particularly limited, and a person skilled in the art can control it by appropriately optimizing the production conditions of the production method of the polycarbonate diol of the present invention described below based on well-known techniques.

[0136] (Structural unit (3)) As described above, the polycarbonate diol of the present invention can contain, within a range not impairing the effects of the present invention, a structural unit (3) derived from a dihydroxy compound (3) other than the compound (1), if necessary. Specific examples of the dihydroxy compound (3) other than the compound (1) include a dihydroxy compound (4) (hereinafter sometimes referred to as "compound (4)") and a dihydroxy compound (5) (hereinafter sometimes referred to as "compound (5)") described later.

[0137] (Compound (4)) In the polycarbonate diol of the present invention, the polycarbonate diol can contain a structural unit (4) derived from a compound (4) represented by the following general formula (4). HO-R 3 -OH (4) (In the above general formula (4), R 3 represents a divalent alkylene group having 3 to 20 carbon atoms which may have a substituent. However, the compound (4) represented by the above general formula (4) does not include the compound (1) represented by the general formula (I-1).)

[0138] In the general formula (4), R 3 represents a divalent alkylene group having 3 to 20 carbon atoms which may have a substituent.

[0139] The structural unit (4) derived from the compound represented by the general formula (4) is represented by, for example, the following general formula (4').

[0140]

Chemical formula

[0141] In the general formula (4), R 3 may be one kind or a plurality of kinds. In the general formula (4), R 3 is a divalent alkylene group having 3 to 20 carbon atoms which may have a substituent. Since flexibility, low-temperature properties, chemical resistance, and heat resistance are all good, R 3It is preferable that the carbon atoms of the main chain constituting the alkylene group are secondary, tertiary or quaternary carbon atoms, and more preferably secondary carbon atoms.

[0142] In the polycarbonate diol of the present invention, by using an aliphatic dihydroxy compound having no aromatic ring structure in the molecular structure such as the compound (4), the handleability of the polycarbonate diol and the flexibility and chemical resistance of the obtained polyurethane can be made excellent.

[0143] The lower limit of the content ratio of the structural unit (4) in the polycarbonate diol of the present invention is not particularly limited. From the viewpoint of good handleability of the polycarbonate diol and good flexibility and chemical resistance of the obtained polyurethane, the lower limit of the content ratio of the structural unit (4) is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 25% by mass or more with respect to 100% by mass of the total mass of the polycarbonate diol. On the other hand, the upper limit of the content ratio of the structural unit (4) is not particularly limited. From the viewpoint of maintaining good handleability of the polycarbonate diol and good flexibility and low-temperature characteristics of the obtained polyurethane, the upper limit of the content ratio of the structural unit (4) is preferably 95% by mass or less, more preferably 75% by mass or less, and still more preferably 50% by mass or less with respect to 100% by mass of the total mass of the polycarbonate diol. The above upper and lower limits can be arbitrarily combined. For example, the content ratio of the structural unit (4) in the polycarbonate diol of the present invention is preferably 5% by mass or more and 95% by mass or less, more preferably 10% by mass or more and 75% by mass or less, and still more preferably 25% by mass or more and 50% by mass or less with respect to 100% by mass of the total mass of the polycarbonate diol.

[0144] In the polycarbonate diol of the present invention, the compound (4) is not particularly limited. For example, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,3-butanediol, 2-methyl-1,4-butanediol, 2-methyl-1,8-octanediol, 1,12-octadecanediol, etc. may be mentioned. Among them, since the balance of the flexibility, low-temperature properties, and chemical resistance of the obtained polyurethane is excellent, it is preferably at least one compound selected from the group consisting of 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,3-butanediol, and 2-methyl-1,4-butanediol. These compounds (4) may be used alone or in combination of two or more.

[0145] (Compound (5)) In the polycarbonate diol of the present invention, the polycarbonate diol can contain a structural unit (5) derived from a compound (5) having a site represented by the following general formula (5) in a part of its structure. -(CH2-O)- (5) (However, the case where the site represented by the above general formula (5) is a part of -CH2-O-H is excluded.)

[0146] In the polycarbonate diol of the present invention, by using a dihydroxy compound such as the compound (5) having a site represented by the structural unit (5) in a part of its structure, the handleability of the polycarbonate diol and the flexibility and low-temperature properties of the obtained polyurethane can be made excellent.

[0147] The lower limit of the content ratio of the structural unit (5) in the polycarbonate diol of the present invention is not particularly limited. From the viewpoints of the handleability of the polycarbonate diol and the flexibility and low-temperature characteristics of the obtained polyurethane, the lower limit of the content ratio of the structural unit (5) is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 25% by mass or more with respect to 100% by mass of the total mass of the polycarbonate diol. On the other hand, the upper limit of the content ratio of the structural unit (5) is not particularly limited. From the viewpoints of the handleability of the polycarbonate diol and maintaining good heat resistance and strength of the obtained polyurethane, the upper limit of the content ratio of the structural unit (5) is preferably 95% by mass or less, more preferably 75% by mass or less, and still more preferably 50% by mass or less with respect to 100% by mass of the total mass of the polycarbonate diol. The above upper and lower limits can be arbitrarily combined. For example, the content ratio of the structural unit (5) in the polycarbonate diol of the present invention is preferably 5% by mass or more and 95% by mass or less, more preferably 10% by mass or more and 75% by mass or less, and still more preferably 25% by mass or more and 50% by mass or less with respect to 100% by mass of the total mass of the polycarbonate diol.

[0148] In the polycarbonate diol of the present invention, the compound (5) is not particularly limited. Examples of the compound (5) include oxyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycol; 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isopropylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isobutylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-cyclohexylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3,5-dimethylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butyl-6-methylphenyl)fluorene, 9,9-bis(4-(3-hydroxy-2,2-dimethylpropoxy)phenyl)fluorene, etc., compounds having an aromatic group in the side chain and an ether group bonded to the aromatic group in the main chain; sugar alcohols represented by the dihydroxy compounds represented by the following formula (6); and compounds having a cyclic ether structure such as spiro glycol represented by the following formula (7). These compounds (5) may be used alone or in combination of two or more.

[0149]

Chemical formula

[0150]

Chemical formula

[0151] Among these compounds (5), it is preferable to use a dihydroxy compound having no aromatic ring structure from the viewpoint of the light resistance of the obtained polyurethane.

[0152] As the anhydro sugar alcohol represented by the dihydroxy compound represented by the above formula (6), specifically, at least one selected from isosorbide, isomannide, and isoidide, which are in a stereoisomeric relationship, can be mentioned. These may be used alone or in combination of two or more. Among them, isosorbide obtained by dehydrating and condensing sorbitol, which is abundantly present as a plant-derived resource and is easily available, is the most preferable from the viewpoints of availability and manufacturability, light resistance, optical properties, moldability, heat resistance, and achievement of sustainable development goals (SDGs).

[0153] [Method for producing polycarbonate diol] The method for producing the polycarbonate diol of the present invention is not particularly limited, and for example, known methods for producing polycarbonate diol described in Polymer Reviews, Vol. 9, p9 - 20 (1994) by Schnell or International Publication No. 2015 / 199070 can be used.

[0154] As a specific embodiment of the method for producing the polycarbonate diol of the present invention, an amine, a dihydroxy compound composition described later, and a carbonate compound described later are polycondensed by a transesterification reaction in the presence of a catalyst described later to obtain a polycarbonate diol containing a structural unit (2) represented by the following general formula (II). A method for producing a polycarbonate diol can be mentioned.

[0155] [Chemical formula]

[0156] (In the above general formula (II), m is an integer of 2 to 20. R 2 represents an alkyl group having 1 to 20 carbon atoms or a hydrogen atom, which may have a substituent.)

[0157] The structural unit (2) in the method for producing the polycarbonate diol of the present invention is treated as having the same meaning as the structural unit (2) described in the description of the polycarbonate diol of the present invention.

[0158] The polycarbonate diol obtained by the method for producing a polycarbonate diol of the present invention can further contain a structural unit (1) represented by the following general formula (I).

[0159] [ka]

[0160] (In the above general formula (I), R is a hydrocarbon group having 2 to 20 carbon atoms, which may have a substituent or a heteroatom.)

[0161] The structural unit (1) in the method for producing the polycarbonate diol of the present invention is treated as having the same meaning as the structural unit (1) described in the description of the polycarbonate diol of the present invention.

[0162] In the method for producing a polycarbonate diol of the present invention, the structural unit (1) preferably contains a structural unit represented by the following general formula (Ia), from the viewpoint of improving the mechanical properties and chemical resistance of the obtained polyurethane.

[0163] [ka]

[0164] (In the above general formula (Ia), n is an integer of 2 to 20.)

[0165] The structural unit represented by the formula (Ia) in the method for producing the polycarbonate diol of the present invention is treated as having the same meaning as the structural unit represented by the formula (Ia) given in the explanation of the polycarbonate diol of the present invention.

[0166] In the method for producing the polycarbonate diol of the present invention, the structural unit (1) can include a structural unit represented by the following general formula (Ib) from the viewpoint of better mechanical properties and chemical resistance of the obtained polyurethane.

[0167]

Chemical formula

[0168] <Dihydroxy compound composition> Examples of the dihydroxy compound composition include a composition containing a dihydroxy compound (1) represented by the following general formula (I-1) (also simply referred to as "compound (1)" in this specification).

[0169]

Chemical formula

[0170] (In the general formula (I-1), R is a hydrocarbon group having 2 to 20 carbon atoms which may have a substituent or a hetero atom.)

[0171] The compound (1) represented by the general formula (I-1) in the method for producing the polycarbonate diol of the present invention is treated as having the same meaning as the compound (1) described in the explanation of the polycarbonate diol of the present invention.

[0172] The compound (1) may be used alone or in combination of two or more.

[0173] The compound (1) in the method for producing the polycarbonate diol of the present invention is not particularly limited, and the same compound as the compound (1) described in the explanation of the polycarbonate diol of the present invention can be used. Hereinafter, the compound (1) in the method for producing the polycarbonate diol of the present invention is treated as having the same meaning as the compound (1) in the polycarbonate diol of the present invention.

[0174] Furthermore, in the method for producing the polycarbonate diol of the present invention, the compound (1) can include a compound represented by the following general formula (Ia-1).

[0175] [Chemical formula]

[0176] (In the above general formula (Ia-1), n is an integer of 2 to 20.)

[0177] The compound represented by the general formula (Ia-1) in the method for producing the polycarbonate diol of the present invention is treated as having the same meaning as the compound represented by the general formula (Ia-1) described in the description of the polycarbonate diol of the present invention.

[0178] In such a case, the content ratio of the compound represented by the general formula (Ia-1) in the compound (1) is not particularly limited. From the viewpoints of the handleability of the polycarbonate diol and the flexibility and low-temperature characteristics of the obtained polyurethane, it is preferably 10% by mass or more, more preferably 30% by mass or more, still more preferably 50% by mass or more, and particularly preferably 70% by mass or more, based on 100% by mass of the total mass of the compound (1). This content ratio may be 90% by mass or more. On the other hand, the upper limit of the content ratio of the compound represented by the general formula (Ia-1) in the compound (1) is not particularly limited, and may be 100% by mass or may be 99% by mass or less based on 100% by mass of the total mass of the compound (1).

[0179] In the method for producing the polycarbonate diol of the present invention, the compound (1) can include, if necessary, a compound represented by the following general formula (Ib-1), that is, 1,6-hexanediol.

[0180] [Chemical formula]

[0181] (amine) In the method for producing the polycarbonate diol of the present invention, the amine can be treated as having the same meaning as the amine that forms the structural unit (2) described in the description of the polycarbonate diol of the present invention.

[0182] Furthermore, in the method for producing the polycarbonate diol of the present invention, the amine can be the amine listed in the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment described in the description of the polycarbonate diol of the present invention.

[0183] In the method for producing the polycarbonate diol of the present invention, from the viewpoint of suppressing the coloring of the obtained polycarbonate diol and achieving a good color tone, and also achieving a good yield during the polymerization of the polycarbonate diol, the upper limit of the content ratio of the amine in the dihydroxy compound composition is preferably 1500 mass ppm or less in terms of nitrogen atom, based on the total mass of the dihydroxy compound composition. The higher the content ratio of the amine, depending on the conditions for producing the polycarbonate diol, the amine may inhibit the catalytic action or exhibit a coloring action, thereby impairing the yield and color tone of the polycarbonate diol. The upper limit of the content ratio of the amine is more preferably 1400 mass ppm or less in terms of nitrogen atom, further preferably 1200 mass ppm or less, particularly preferably 1000 mass ppm or less, and most preferably 500 mass ppm or less. On the other hand, the lower limit of the content ratio of the amine is not particularly limited. From the viewpoint of economy, and also from the viewpoint of appropriately increasing the molecular weight distribution of the polyurethane obtained using the polycarbonate diol of the present invention to enhance the mechanical properties of the polyurethane and suppress the variation in the mechanical properties, the lower limit of the content ratio of the amine is usually preferably 1 mass ppm or more in terms of nitrogen atom, based on the total mass% of the dihydroxy compound composition, more preferably 10 mass ppm or more, further preferably 50 mass ppm or more, particularly preferably 100 mass ppm or more, and most preferably 200 mass ppm or more. The above upper and lower limits can be arbitrarily combined. For example, in the method for producing a polycarbonate diol of the present invention, the content ratio of the amine contained in the dihydroxy compound composition is preferably 1 mass ppm or more and 1500 mass ppm or less in terms of nitrogen atom, more preferably 10 mass ppm or more and 1400 mass ppm or less, still more preferably 50 mass ppm or more and 1200 mass ppm or less, particularly preferably 100 mass ppm or more and 1000 mass ppm or less, and especially preferably 200 mass ppm or more and 500 mass ppm or less, based on the total mass of the dihydroxy compound composition.

[0184] In addition, in the method for producing a polycarbonate diol of the present invention, when the upper limit of the content ratio of the amine contained in the dihydroxy compound composition is 100 mass ppm or less in terms of nitrogen atom based on the total mass of the dihydroxy compound composition, the higher the content ratio of the amine, the more the coloring of the obtained polycarbonate diol can be suppressed and the color tone can be controlled well. The higher the content ratio of the amine contained in the dihydroxy compound composition is more than 100 mass ppm in terms of nitrogen atom, the more likely the amine is to inhibit the catalytic action or exhibit a coloring action, thereby tending to impair the yield and color tone of the polycarbonate diol. The upper limit of the content ratio of the amine is preferably 90 mass ppm or less, more preferably 80 mass ppm or less, still more preferably 70 mass ppm or less, and most preferably 60 mass ppm or less, in terms of nitrogen atom. On the other hand, the lower limit of the content ratio of the amine is not particularly limited, but from the viewpoint of economy, it is usually preferably 0.1 mass ppm or more, more preferably 1 mass ppm or more, still more preferably 2 mass ppm or more, particularly preferably 5 mass ppm or more, and most preferably 10 mass ppm or more, in terms of nitrogen atom based on the total mass% of the dihydroxy compound composition. The above upper and lower limits can be arbitrarily combined. For example, in the method for producing a polycarbonate diol of the present invention, when the content of the amine contained in the dihydroxy compound composition is 100 mass ppm or less in terms of nitrogen atom relative to the total mass of the dihydroxy compound composition, the content ratio of the amine contained in the dihydroxy compound composition is preferably 0.1 mass ppm or more and 100 mass ppm or less in terms of nitrogen atom relative to the total mass of the dihydroxy compound composition, more preferably 1 mass ppm or more and 90 mass ppm or less, still more preferably 2 mass ppm or more and 80 mass ppm or less, particularly preferably 5 mass ppm or more and 70 mass ppm or less, and most preferably 10 mass ppm or more and 60 mass ppm or less.

[0185] The method for controlling the content ratio of the amine in the dihydroxy compound composition is not particularly limited. As described above, for example, when sugars and the like are used as biomass resources as raw materials and they are fermented with bacterial cells to obtain the compound (1), the amine is by-produced. Therefore, it can be controlled by adjusting the type of bacterial cells, fermentation time, distillation and purification conditions, etc.

[0186] <aldehyde> In the method for producing a polycarbonate diol of the present invention, when the content ratio of the amine contained in the dihydroxy compound composition is 100 mass ppm or less in terms of nitrogen atom, the higher the content of the amine, the more effectively the generation of aldehyde in the dihydroxy compound composition can be suppressed for the reasons described below. Therefore, the effect of suppressing the coloring of the obtained polycarbonate diol can be more significantly obtained. As described above, according to the studies of the present inventors, the dihydroxy compound composition, which is a raw material of the polycarbonate diol, contains an aldehyde for the reasons described above. And when producing a polycarbonate diol using such a dihydroxy compound composition, or when storing the obtained polycarbonate diol for a long period of time, the aldehyde generates radicals by heating or oxidation, and an aldehyde group, a carboxylic acid, a double bond, etc. are generated in the dihydroxy compound or the polycarbonate diol. As a result, a conjugated structure is formed in the structure of the polycarbonate diol, and it is presumed that the polycarbonate diol is colored. The amine in the dihydroxy compound composition is presumed to be able to suppress the coloring of the obtained polycarbonate diol because it suppresses the by-production of aldehyde and the radical generation of aldehyde.

[0187] The aldehyde in the method for producing a polycarbonate diol of the present invention can be treated as synonymous with the aldehyde mentioned in the description of the polycarbonate diol of the present invention. That is, the aforementioned aldehyde compound and its acetal, which is an acetal-modified product, are referred to as "aldehyde".

[0188] In the method for producing a polycarbonate diol of the present invention, when the content ratio of the amine contained in the dihydroxy compound composition is 100 mass ppm or less in terms of nitrogen atom, the upper limit of the content ratio of the aldehyde in the dihydroxy compound composition is not particularly limited. From the viewpoint of obtaining a sufficient effect by the amine, the upper limit of the content ratio of the aldehyde is 980 mass ppm or less, preferably 950 mass ppm or less, more preferably 900 mass ppm or less, still more preferably 850 mass ppm or less, and particularly preferably 800 mass ppm or less with respect to the total mass of the dihydroxy compound composition. On the other hand, the lower limit of the content ratio is not particularly limited. Usually, from the viewpoint of economy, the lower limit of the content ratio of the aldehyde is 1 mass ppm or more, preferably 10 mass ppm or more, more preferably 50 mass ppm or more, still more preferably 100 mass ppm or more, and particularly preferably 200 mass ppm or more with respect to the total mass of the dihydroxy compound composition. The above upper and lower limits can be arbitrarily combined. For example, when the content ratio of the amine contained in the dihydroxy compound composition is 100 mass ppm or less in terms of nitrogen atoms, in the method for producing the polycarbonate diol of the present invention, the content ratio of the aldehyde contained in the dihydroxy compound composition is usually 1 mass ppm or more and 980 mass ppm or less, preferably 10 mass ppm or more and 950 mass ppm or less, more preferably 50 mass ppm or more and 900 mass ppm or less, still more preferably 100 mass ppm or more and 850 mass ppm or less, and particularly preferably 200 mass ppm or more and 800 mass ppm or less, based on the total mass of the dihydroxy compound composition.

[0189] The method for controlling the content ratio of the aldehyde in the dihydroxy compound composition is not particularly limited. For example, when obtaining the compound (1) by the hydrogenation reaction of a carboxylic acid or a carboxylic acid ester, it can be controlled by adjusting the conversion rate of the carboxylic acid or the carboxylic acid ester in the hydrogenation reaction step.

[0190] For example, in the production stage of the dihydroxy compound composition, the higher the conversion rate, the lower the content ratio of the aldehyde in the obtained dihydroxy compound composition. Therefore, as a method for reducing the content ratio of the aldehyde, a method of increasing the conversion rate can be mentioned. On the other hand, the content ratio of the aldehyde in the dihydroxy compound composition increases by oxidation. Therefore, as a method for increasing the content ratio of the aldehyde in the production stage of the dihydroxy compound composition, for example, a method of increasing the content ratio of the aldehyde to a desired value by heating the dihydroxy compound composition in a raw material tank or the like in the presence of oxygen can be mentioned.

[0191] In order to reduce the content ratio of aldehyde in the production stage of the dihydroxy compound composition, methods such as increasing the amount of catalyst used in the hydrogenation reaction of carboxylic acid or carboxylic acid ester which is the raw material of the dihydroxy compound, lengthening the residence time, or excessive hydrogen pressure can be used. However, this method has a large load in the production stage and is not easy. Also, since acetal requires a hydrogenation catalytic ability different from that of aldehyde, it is difficult to undergo a hydrogenation reaction with a hydrogenation catalyst for aldehyde, and acetal remains in the compound (1).

[0192] Furthermore, after the hydrogenation reaction step, the compound (1) can be purified by distillation. At that time, even in the distillation stage, acetal by-produced in the hydrogenation reaction step may decompose into aldehyde and mix into the purified compound (1). Also, aldehyde may react with a hydroxy group to form acetal and mix into the compound (1).

[0193] Generally, aldehyde in a dihydroxy compound composition with a small number of carbon atoms can be separated relatively easily by distillation purification. However, when the boiling points of the compound (1) and aldehyde are close and it is difficult to separate as acetal, aldehyde or acetal tends to remain in the compound (1).

[0194] (Content ratio of structural unit (2) in polycarbonate diol) In the method for producing the polycarbonate diol of the present invention, the upper limit of the content ratio of the structural unit (2) derived from the amine contained in the obtained polycarbonate diol is, for the same reason as described for the polycarbonate diol of the present invention, preferably 1200 mass ppm or less, more preferably 1000 mass ppm or less, still more preferably 900 mass ppm or less, particularly preferably 700 mass ppm or less, and especially preferably 500 mass ppm or less in terms of nitrogen atom conversion with respect to the total mass of the polycarbonate diol. On the other hand, for the same reasons as described for the polycarbonate diol of the present invention, the lower limit of the content of the structural unit (2) is preferably 1 ppm by mass or more, more preferably 10 ppm by mass or more, still more preferably 50 ppm by mass or more, particularly preferably 100 ppm by mass or more, and especially preferably 150 ppm by mass or more in terms of nitrogen atom relative to the total mass of the polycarbonate diol. The above upper and lower limits can be arbitrarily combined. For example, in the method for producing a polycarbonate diol of the present invention, the content ratio of the structural unit (2) contained in the obtained polycarbonate diol is preferably 1 ppm by mass or more and 1200 ppm by mass or less, more preferably 10 ppm by mass or more and 1000 ppm by mass or less, still more preferably 50 ppm by mass or more and 900 ppm by mass or less, particularly preferably 100 ppm by mass or more and 700 ppm by mass or less, and especially preferably 150 ppm by mass or more and 500 ppm by mass or less in terms of nitrogen atom relative to the total mass of the polycarbonate diol.

[0195] In the method for producing a polycarbonate diol of the present invention, when the content ratio of the amine contained in the dihydroxy compound composition is 100 ppm by mass or less in terms of nitrogen atom, the upper limit of the content of the structural unit (2) in the obtained polycarbonate diol is usually 80 ppm by mass or less, preferably 70 ppm by mass or less, more preferably 60 ppm by mass or less, still more preferably 50 ppm by mass or less, and most preferably 40 ppm by mass or less in terms of nitrogen atom relative to the total mass of the polycarbonate diol for the same reasons as described for the polycarbonate diol of the present invention. On the other hand, for the same reasons as described for the polycarbonate diol of the present invention, the lower limit of the content of the structural unit (2) is preferably 0.1 ppm by mass or more, more preferably 1 ppm by mass or more, still more preferably 2 ppm by mass or more, particularly preferably 5 ppm by mass or more, and most preferably 10 ppm by mass or more in terms of nitrogen atom relative to the total mass of the polycarbonate diol. The above upper and lower limits can be arbitrarily combined. For example, in the method for producing a polycarbonate diol of the present invention, the content of the structural unit (2) contained in the obtained polycarbonate diol is preferably 0.1 mass ppm or more and 80 mass ppm or less in terms of nitrogen atom, more preferably 1 mass ppm or more and 70 mass ppm or less, still more preferably 2 mass ppm or more and 60 mass ppm or less, particularly preferably 5 mass ppm or more and 50 mass ppm or less, and most preferably 10 mass ppm or more and 40 mass ppm or less, based on the total mass of the polycarbonate diol.

[0196] Furthermore, in the method for producing a polycarbonate diol of the present invention, when the content ratio of the amine contained in the dihydroxy compound composition is 100 mass ppm or less in terms of nitrogen atom, in the obtained polycarbonate diol, the higher the content of the amine, the more effectively the generation of aldehyde in the dihydroxy compound composition can be suppressed for the reasons described above. And since the generation of aldehyde can be more effectively suppressed, the effect of suppressing the coloring of the obtained polycarbonate diol can be more remarkably obtained. Also, in the method for producing a polycarbonate diol of the present invention, the lower limit and the upper limit of the content ratio of the aldehyde in the obtained polycarbonate diol are the same as the lower limit and the upper limit of the content ratio of the aldehyde in the polycarbonate diol of the present invention, respectively.

[0197] (Molecular weight of polycarbonate diol) In the method for producing a polycarbonate diol of the present invention, the number average molecular weight of the obtained polycarbonate diol is preferably 250 or more and 5000 or less, more preferably 300 or more and 4000 or less, and still more preferably 400 or more and 3000 or less, for the same reasons as described for the polycarbonate diol of the present invention.

[0198] (Compound (4) and Compound (5)) Furthermore, in the method for producing the polycarbonate diol of the present invention, for the same reasons as described for the polycarbonate diol of the present invention, it is preferable that the dihydroxy compound composition further contains at least one of a compound (4) represented by the following general formula (4) and a compound (5) having a moiety represented by the following general formula (5) in a part of its structure. HO-R 3 -OH (4) (In the above general formula (4), R 3 represents a divalent alkylene group having 3 to 20 carbon atoms which may have a substituent. However, the compound (4) represented by the above general formula (4) does not include the compound (1) represented by the general formula (I-1).) -(CH2-O)- (5) (However, the case where the moiety represented by the above general formula (5) is a part of -CH2-O-H is excluded.)

[0199] The compound (4) and the compound (5) in the method for producing the polycarbonate diol of the present invention are treated as having the same meaning as the compound (4) and the compound (5) described in the description of the polycarbonate diol of the present invention, respectively.

[0200] In the method for producing the polycarbonate diol of the present invention, for the same reasons as described for the polycarbonate diol of the present invention, it is preferable that the compound (5) is at least one selected from isosorbide, isomannide, and isoidide.

[0201] In the method for producing the polycarbonate diol of the present invention, the lower limit and the upper limit of the content ratio of the structural unit (4) and the structural unit (5) in the obtained polycarbonate diol are the same as the lower limit and the upper limit of the content ratio of the structural unit (4) and the structural unit (5) in the polycarbonate diol of the present invention, respectively.

[0202] <Carbonate compound> The carbonate compound (which may be referred to as "carbonic acid diester") that can be used in the method for producing the polycarbonate diol of the present invention is not particularly limited as long as the effects of the present invention are not impaired. Examples of the carbonate compound that can be used include known carbonate compounds used in the synthesis of polycarbonate diols such as dialkyl carbonate, diaryl carbonate, or alkylene carbonate. The carbonate compound to be used can be appropriately selected by those skilled in the art according to the use of the polycarbonate diol, production conditions, and the like. For example, from the viewpoint of the reactivity between the dihydroxy compound and the carbonate compound, diaryl carbonate is preferred as the carbonate compound, and from the viewpoint of economy, dialkyl carbonate or alkylene carbonate is preferred as the carbonate compound. Specific examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, diphenyl carbonate, ethylene carbonate, and the like.

[0203] The amount of the carbonate compound used is not particularly limited. For example, the conditions described in International Publication No. 2015 / 199070 can be appropriately optimized by those skilled in the art according to known techniques and used.

[0204] <Catalyst> In the method for producing the polycarbonate diol of the present invention, when a polycarbonate diol is obtained by polycondensing a dihydroxy compound composition and a carbonate compound by a transesterification reaction, a known transesterification catalyst (hereinafter may be referred to as "catalyst") used in the synthesis of polycarbonate diols can be used as a catalyst for promoting the transesterification reaction. In that case, if an excessive amount of the catalyst remains in the obtained polycarbonate diol, it may inhibit the reaction or excessively promote the reaction when producing polyurethane using the polycarbonate diol. The type of the catalyst and the amount of the catalyst remaining in the polycarbonate diol are not particularly limited. As the catalyst, for example, the conditions described in International Publication No. WO2015 / 199070 can be appropriately optimized by those skilled in the art according to the known techniques and used.

[0205] <Catalyst deactivator> As described above, when a catalyst is used in the polymerization reaction, the catalyst usually remains in the obtained polycarbonate diol. Due to the remaining catalyst, when the polycarbonate diol is heated, the molecular weight may increase, the composition may change, etc., or the control of the polyurethane-forming reaction may become impossible. In order to suppress the influence of the remaining catalyst, if necessary, a catalyst deactivator such as a phosphorus-based compound, which is approximately equimolar to the transesterification catalyst used, can be added to deactivate the transesterification catalyst. Further, after the addition, the transesterification catalyst can be efficiently deactivated by heat treatment or the like. The type, amount used, and heat treatment conditions of the catalyst deactivator are not particularly limited. As the catalyst deactivator, for example, the conditions described in International Publication No. WO2015 / 199070 can be appropriately optimized by those skilled in the art according to the known techniques and used.

[0206] [Polyurethane] The polyurethane of the present invention is a polyurethane produced using the polycarbonate diol of the present invention. The method for producing the polyurethane of the present invention is not particularly limited. As the method for producing the polyurethane of the present invention, for example, the known reaction conditions of polyurethane described in International Publication No. WO2015 / 016261, International Publication No. WO2018 / 088575, etc. can be appropriately optimized by those skilled in the art according to the known techniques and used.

[0207] For example, the polyurethane of the present invention can be produced by reacting the polycarbonate diol of the present invention, a polyol other than the polycarbonate diol of the present invention used as necessary, a polyisocyanate described below, and a chain extender described below used as necessary, in the range from room temperature to 200°C.

[0208] When using a chain extender, the chain extender may be added from the beginning of the reaction or during the reaction. For example, the polycarbonate diol of the present invention and an excess of polyisocyanate are first reacted to produce a prepolymer having isocyanate groups at the terminals, and then a chain extender is added and reacted with the prepolymer to increase the degree of polymerization of the polymer, whereby the polyurethane of the present invention can be produced.

[0209] <Polyisocyanate> As the polyisocyanate used in the production of the polyurethane of the present invention, known polyisocyanates used in the production of polyurethanes can be used. The polyisocyanate is not particularly limited. For example, various aliphatic, alicyclic or aromatic polyisocyanate compounds described in International Publication No. 2015 / 016261 and International Publication No. 2018 / 088575 can be used.

[0210] Specifically, known aliphatic diisocyanates such as tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate; known alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and 1,3-bis(isocyanatomethyl)cyclohexane; known aromatic diisocyanates such as xylylene diisocyanate, 4,4'-diphenyl diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate and the like can be mentioned. These may be used alone or in combination of two or more.

[0211] Among these, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and isophorone diisocyanate are preferred in terms of the favorable balance of the physical properties of the resulting polyurethane and the fact that they can be obtained inexpensively and in large quantities industrially.

[0212] <Chain extender> As the chain extender used in the production of the polyurethane of the present invention, known chain extenders used in the production of polyurethane can be used. The chain extender is not particularly limited. Examples of the chain extender include low molecular polyols, amines, water, etc. described in International Publication No. 2015 / 016261 and International Publication No. 2018 / 088575.

[0213] Specifically, linear diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol; diols having branched chains such as 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol; diols having ether groups such as diethylene glycol, propylene glycol; diols having alicyclic structures such as 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-dihydroxyethylcyclohexane; diols having aromatic groups such as xylylene glycol, 1,4-dihydroxyethylbenzene, 4,4'-methylenebis(hydroxyethylbenzene); polyols such as glycerin, trimethylolpropane, pentaerythritol; hydroxyamines such as N-methylethanolamine, N-ethylethanolamine; polyamines such as ethylenediamine, 1,3-diaminopropane, hexamethylenediamine, triethylenetetramine, diethylenetriamine, isophoronediamine, 4,4'-diaminodicyclohexylmethane, 2-hydroxyethylpropylenediamine, 4,4'-diphenylmethanediamine, xylylenediamine, diphenyldiamine, hydrazine, piperazine; and water, etc. can be mentioned. These chain extenders may be used alone or in combination of two or more kinds.

[0214] Among these, ethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexanedimethanol, 1,4-dihydroxyethylcyclohexane, ethylenediamine, 1,3-diaminopropane, isophoronediamine, 4,4'-diaminodicyclohexylmethane are preferable in terms of the favorable balance of the physical properties of the obtained polyurethane and the availability in large quantities at low cost industrially.

[0215] <Chain terminator> When producing the polyurethane of the present invention, for the purpose of controlling the molecular weight of the polyurethane, a known chain terminator used in the production of polyurethane can be used as needed. The chain terminator is not particularly limited. Examples of the chain terminator include compounds having one active hydrogen group described in International Publication No. 2015 / 016261 and International Publication No. 2018 / 088575.

[0216] Specifically, monohydric alcohols such as methanol, ethanol, propanol, butanol, and hexanol, and secondary amines such as diethylamine, dibutylamine, di-n-propylamine, n-butylamine, monoethanolamine, and diethanolamine can be mentioned. These may be used alone or in combination of two or more.

[0217] <Catalyst> When producing the polyurethane of the present invention, a known catalyst used in the production of polyurethane can be used. The catalyst is not particularly limited. As the catalyst, for example, known polymerization catalysts typified by tertiary amines and organometallic salts such as tin and titanium described in International Publication No. 2015 / 016261 and International Publication No. 2018 / 088575 can be used.

[0218] <Solvent> When producing the polyurethane of the present invention, a solvent may be used as needed. The solvent is not particularly limited. Examples of the solvent include solvents described in International Publication No. 2015 / 016261 and International Publication No. 2018 / 088575.

[0219] Specifically, dimethylformamide, diethylformamide, dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, methyl isobutyl ketone, dioxane, cyclohexanone, benzene, toluene, ethyl cellosolve, etc. can be mentioned. These may be used alone or in combination of two or more.

[0220] <Usage and Method of Use> In the method for producing the polyurethane of the present invention, the usage amounts and usage methods of the polyisocyanate, the chain extender, the chain terminator, the catalyst, and the solvent are not particularly limited, and those skilled in the art can appropriately optimize and use the conditions described in International Publication No. 2015 / 016261 and International Publication No. 2018 / 088575 according to known techniques.

[0221] <Weight-average Molecular Weight (Mw) and Molecular Weight Distribution (Mw / Mn) of Polyurethane> The lower limit of the weight-average molecular weight (Mw) of the polyurethane of the present invention is not particularly limited. From the viewpoint of obtaining good mechanical properties and chemical resistance of the obtained polyurethane, the lower limit of the weight-average molecular weight (Mw) is preferably 50,000 or more, more preferably 100,000 or more, and even more preferably 150,000 or more. On the other hand, the upper limit of the weight-average molecular weight (Mw) is not particularly limited. From the viewpoint of maintaining good chemical resistance of the obtained polyurethane, the upper limit of the weight-average molecular weight (Mw) is preferably 500,000 or less, more preferably 300,000 or less, and even more preferably 200,000 or less. The above upper and lower limits can be arbitrarily combined. For example, the weight-average molecular weight (Mw) of the polyurethane of the present invention is preferably 50,000 or more and 500,000 or less, more preferably 100,000 or more and 300,000 or less, and even more preferably 150,000 or more and 200,000 or less.

[0222] The lower limit of the molecular weight distribution (Mw / Mn) of the polyurethane of the present invention is not particularly limited. From the viewpoint of obtaining good mechanical properties and chemical resistance of the obtained polyurethane, the lower limit of the molecular weight distribution (Mw / Mn) is preferably 1.50 or more, more preferably 2.00 or more, and even more preferably 2.50 or more. On the other hand, the upper limit of the molecular weight distribution (Mw / Mn) is not particularly limited. From the viewpoint of maintaining good mechanical properties and chemical resistance of the obtained polyurethane, the upper limit of the molecular weight distribution (Mw / Mn) is preferably 4.00 or less, more preferably 3.00 or less, and even more preferably 2.90 or less. The above upper and lower limits can be combined in any desired manner. For example, the molecular weight distribution (Mw / Mn) of the polyurethane of the present invention is preferably 1.50 or more and 4.00 or less, more preferably 2.00 or more and 3.00 or less, and even more preferably 2.50 or more and 2.90 or less.

[0223] The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) are measured by gel permeation chromatography (GPC measurement), and the measurement conditions are as described in the examples below.

[0224] <Polyurethane applications> The polyurethane of the present invention has excellent mechanical properties and chemical resistance, as well as good heat resistance and weather resistance, and can therefore be widely used in foams, elastomers, elastic fibers, paints, fibers, pressure-sensitive adhesives, adhesives, flooring materials, sealants, medical materials, artificial leathers, synthetic leathers, coating agents, active-energy radiation-curable polymer compositions, etc.

[0225] In particular, when the polyurethane of the present invention is used in applications such as active energy radiation-curable polymer compositions, artificial leather, synthetic leather, paints such as water-based polyurethane paints, coating agents, elastic fibers, pressure-sensitive adhesives, and adhesives, the following effects can be obtained. That is, the polyurethane of the present invention has a good balance of chemical resistance, flexibility, heat resistance, and weather resistance, and therefore can impart good properties such as high durability and sufficient flexibility to parts that come into contact with human skin or are used with cosmetic agents or disinfectant alcohol, as well as resistance to physical impact, etc. Furthermore, the polyurethane of the present invention can be suitably used for automotive applications that require heat resistance and outdoor applications that require weather resistance.

[0226] [Action and Effect (1)] Since the polycarbonate diol of the present invention contains the structural unit (2), the mechanical properties and variations in the mechanical properties of the resulting polyurethane are suppressed. The reason for this is not clear, but is presumed to be as follows.

[0227] When producing polyurethane using the polycarbonate diol of the present invention as a raw material, the structural unit (2) contained in the polycarbonate diol is considered to be incorporated in a form that forms an amide bond in the polyurethane. And, by improving the interaction due to hydrogen bonding via the amide bond between polyurethane molecules, it is presumed that the mechanical properties of the polyurethane are improved because the amide bond portion acts as a crosslinking point or a crystalline hard segment structure.

[0228] Further, the polycarbonate diol containing the structural unit (2) has an appropriate amide bond in the polycarbonate diol. And, the polyurethane obtained using the polycarbonate diol has the amide bond in its structure. For this reason, the interaction due to hydrogen bonding via the amide bond between polyurethane molecules is improved, and the viscosity of the polyurethane or the composition containing the polyurethane is improved. As a result, it becomes possible to efficiently improve the uniformity of the polyurethane composition by a stirring operation. Also, by appropriately improving the viscosity, the coating stability and molding stability of the polyurethane or the polyurethane-containing composition are improved. As a result, it is presumed that the variation in mechanical properties in the obtained polyurethane product is suppressed by improving the dimensional stability of the obtained film-like material, fiber-like material, and other molded articles.

[0229] [Effect (2)] In the polycarbonate diol of the present invention, when the content of the structural unit (2) in the polycarbonate diol is 80 mass ppm or less in terms of nitrogen atom, the higher the content of the structural unit (2), the more the coloring of the obtained polycarbonate diol is suppressed and the color tone becomes better. The reason for this is not clear, but it is presumed as follows.

[0230] According to the study by the present inventors, the dihydroxy compound composition, which is a raw material of the polycarbonate diol of the present invention, may contain an aldehyde for the reasons described above. When producing polycarbonate diol using such a dihydroxy compound composition or when storing the obtained polycarbonate diol for a long period of time, the aldehyde generates radicals by heating or oxidation, and aldehyde groups, carboxylic acids, double bonds, etc. are generated in the dihydroxy compound or polycarbonate diol. As a result, it is presumed that a conjugated structure is formed in the structure of the polycarbonate diol and the polycarbonate diol is colored. The structural unit (2) derived from an amine in the dihydroxy compound composition or an amine contained in the polycarbonate diol suppresses the by-production of aldehydes and suppresses the radical generation of aldehydes. Therefore, it is presumed that the coloring of the obtained polycarbonate diol can be suppressed, and further, by setting the content ratio of the amine or the structural unit (2) to a predetermined value or less, the coloring of the polycarbonate diol due to the excessive presence of the amine or the structural unit (2) itself can be suppressed.

Examples

[0231] Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to these examples as long as the gist thereof is not exceeded.

[0232] [Evaluation method] In the following, the evaluation methods for each physical property value are as follows.

[0233] [Evaluation method: Polycarbonate diol] <Content of the structural unit derived from amine (amine content)> The content of the structural unit derived from an amine (hereinafter referred to as "amine-derived structural unit") contained in the structure of the polycarbonate diol (hereinafter sometimes abbreviated as "PCD") obtained in the examples and comparative examples was measured according to the following procedure. Here, the amine-derived structural unit corresponds to the structural unit (2) in the polycarbonate diol.

[0234] In Examples 1 to 6 and Comparative Example 1 below, 6-amino-1-hexanol, which is a primary amine, is added as the amine in the present invention. However, even when the polycarbonate diol contains a structural unit derived from a secondary amine such as dihexylamine used in Examples 9 to 11, those skilled in the art can measure the content of the structural unit derived from the secondary amine contained in the structure of the polycarbonate diol by combining well-known techniques in the following procedure.

[0235] The polycarbonate diol was dissolved in CDCl3, and using a nuclear magnetic resonance spectrometer (400 MHz, manufactured by JEOL Ltd., model name: ECZ400S), under the conditions of a measurement temperature of 30°C and an integration number of 64 times, 1 1H-NMR measurement was performed. From the 1 1H-NMR measurement results obtained, three peaks observed at the following signal positions were identified, and the integration values A to C of each peak were obtained. Integration value of 2H protons of the α-methylene group of the amine-derived structural unit present at δ 3.15 to 3.05 ppm = A Integration value of 2H proton peak of the methylene group adjacent to the hydroxyl group terminal in the polycarbonate diol present at δ 3.69 to 3.50 ppm = B Integration value of 4H proton peak of the γ-methylene group of the structure derived from 1,6-hexanediol in the polycarbonate diol present at δ 1.49 to 1.30 ppm = C

[0236] Also, the integration value of the peak derived from the amine-derived structural unit was designated as "AM". Similarly, the integration value of the peak of the structural unit at the terminal of the polycarbonate diol derived from 1,6-hexanediol (hereinafter abbreviated as "16HD") was designated as "16HD m ". Also, the integration value of the peak of the structural unit derived from 16HD in the polycarbonate diol other than the terminal of the polycarbonate diol was designated as "16HD o ". Taking into account the respective number of protons, the integral value per proton was calculated by the following formula. AM = A÷2 16HD m = B÷2 16HD o =(C - 16HD m ×4)÷4

[0237] Next, using the following formula, the ratio (number of diol units) of the total amount of structural units derived from 16HD to the total amount of structural units derived from 16HD in the structural units at the ends of the polycarbonate diol, and from the molecular weights of the respective structural units of the polycarbonate diol, the number average molecular weight M(PCD) of the polycarbonate diol was calculated.

[0238]

Number

[0239] In the above formula, M(16HD o ) represents the molecular weight (=116) of the structural unit derived from 16HD in the polycarbonate diol other than at the ends of the polycarbonate diol, and M(carbonyl group) represents the molecular weight (=28) of the carbonyl group.

[0240] Using the above value and the following formula, the content ratio (unit: mass%) of the amine-derived structural unit to the total mass of 100% of the polycarbonate diol contained in the structure of the polycarbonate diol was calculated.

[0241]

Number

[0242] In the above formula, "M(amine)" represents the molecular weight (=117) of 6-amino-1-hexanol which is a primary amine.

[0243] Next, using the above value and the following formula, the content ratio (unit: mass ppm) in terms of nitrogen atoms of the amine-derived structural unit contained in the structure of the polycarbonate diol was calculated.

[0244] [Number]

[0245] In addition, regarding the content ratio of amine-derived structural units in polycarbonate diol containing 1,6-hexanediol, 1,4-butanediol (hereinafter abbreviated as "14BG"), neopentyl glycol (hereinafter abbreviated as "NPG"), or isosorbide (hereinafter abbreviated as "ISB") as the dihydroxy compound, which was used in the examples, 1 From the H-NMR measurement results, the integral value of the peak derived from the structural unit at the end of the polycarbonate diol, the integral value of the peak derived from the structural unit in the polycarbonate diol other than the end of the polycarbonate diol, the number average molecular weight M(PCD) of the polycarbonate diol, and using the formula according to the above formula, the content ratio (unit: mass ppm) in terms of nitrogen atoms of the amine-derived structural unit in the polycarbonate diol with respect to 100% of the total mass of the polycarbonate diol was calculated.

[0246] At that time, M(14BG o ) is the molecular weight (=88) of the structural unit derived from 14BG in the polycarbonate diol other than the end of the polycarbonate diol. Similarly, M(NPG o ) is the molecular weight (=102) of the structural unit derived from NPG, and M(ISB o ) is the molecular weight (=144) of the structural unit derived from ISB. Also, "M(amine)" is the molecular weight (=185) of dihexylamine which is a secondary amine.

[0247] <Content ratio of aldehyde> The content ratio of aldehyde (hereinafter abbreviated as "ALD") in the polycarbonate diol obtained in the examples and comparative examples was measured according to the following procedure. In this evaluation, the definitions of "aldehyde" and "content ratio of aldehyde" are as described in the above description of aldehyde.

[0248] The polycarbonate diol was dissolved in CDCl3, and 1H-NMR measurement was performed using a nuclear magnetic resonance spectrometer (400 MHz, manufactured by JEOL Ltd., model name: ECZ400S) under the conditions of a measurement temperature of 30 °C and an integration number of 64 times. 1 The 1H-NMR measurement was carried out. From the obtained 1 1H-NMR measurement results, the integration value of the 1H proton of the aldehyde group in the aldehyde present at δ 9.80 to 9.75 ppm was defined as the integration value of the peak derived from the aldehyde "ALD m ".

[0249] Next, using the value of M(PCD) used when calculating the content of the amine-derived structural unit and the following formula, the content ratio (unit: mass ppm) of the aldehyde with respect to 100% of the total mass of the polycarbonate diol was calculated.

[0250]

Equation

[0251] In the above formula, "M(aldehyde)" represents the molecular weight (= 116) of the aldehyde (6-hydroxyhexanal).

[0252] Also, regarding the content ratio of the aldehyde in the polycarbonate diol containing 1,6-hexanediol, 1,4-butanediol, and neopentyl glycol as dihydroxy compounds used in the examples, 1 From the 1H-NMR measurement results, using the integration value of the peak derived from the structural unit at the end of the polycarbonate diol, the integration value of the peak derived from the structural unit in the polycarbonate diol other than the end, the number average molecular weight M(PCD) of the polycarbonate diol, and the formula according to the above formula, the content ratio (unit: mass ppm) of the aldehyde in the polycarbonate diol with respect to 100% of the total mass of the polycarbonate diol was calculated.

[0253] <Color tone> For the suppression of coloring of the polycarbonate diols obtained in the examples and comparative examples, i.e., as an index of color tone, in accordance with JIS K0071-1 (1998), a sample of the polycarbonate diol was placed in a colorimetric tube and compared with a standard solution, and the APHA value was measured. As the reagent, a chromaticity standard solution of 1000 degrees (1 mg Pt / mL) (manufactured by Kishida Chemical Co., Ltd.) was used.

[0254] <Number average molecular weight (M(PCD)) of polycarbonate diol> The polycarbonate diols obtained in the examples and comparative examples were dissolved in CDCl3, and 1H-NMR was measured using a nuclear magnetic resonance spectrometer (400 MHz, manufactured by JEOL Ltd., model name: AL-400). 1 From the signal positions of each component, the number average molecular weight (M(PCD)) was calculated by the above calculation method.

[0255] <Number average molecular weight (Mn) determined from the hydroxyl value of the polycarbonate diol after distillation> The hydroxyl values (unit: mg KOH / g) of the polycarbonate diols obtained in the examples and comparative examples were measured by a method using an acetylating reagent in accordance with JIS K1557-1. Then, from the obtained hydroxyl values, the number average molecular weight (Mn) of the polycarbonate polyol was calculated using the following formula. Number average molecular weight (Mn) = (molecular weight of KOH) × 2000 / hydroxyl value

[0256] [Evaluation method: Dihydroxy compound composition] <Content of amine> The content of amine in 1,6-hexanediol used in the examples and comparative examples as the dihydroxy compound composition was measured according to the following procedure. In this evaluation, the definition of "content of amine" is as described in the above explanation.

[0257] In Examples 1 to 6 and Comparative Example 1 below, 6-amino-1-hexanol, which is a primary amine, is added as the amine in the present invention. However, even when the dihydroxy compound composition contains a secondary amine such as dihexylamine used in Examples 9 to 11, a person skilled in the art can measure the content of the secondary amine contained in the dihydroxy compound composition by combining well-known techniques with the following procedures.

[0258] 1,6-Hexanediol was dissolved in CDCl3, and using a nuclear magnetic resonance spectrometer (400 MHz, manufactured by JEOL Ltd., model name: ECZ400S), under the conditions of a measurement temperature of 30 °C and an integration number of 32 times, 1 1H-NMR measurement was performed.

[0259] From the 1 1H-NMR measurement results, the integration value a of the peak of the 2H proton of the α-methylene group at the amine terminal present at δ 3.15 to 3.05 ppm, the integration value b of the peak of the 2H proton of the α-methylene group at the hydroxyl group terminal present at δ 3.69 to 3.50 ppm, and using the following formula, the content ratio (unit: mass%) of the amine in the dihydroxy compound composition with respect to 100% of the total mass of the dihydroxy compound composition was calculated.

[0260]

Equation

[0261] In the above formula, "M(amine)" represents the molecular weight (= 117) of 6-amino-1-hexanol, which is a primary amine, and "M(16HD)" represents the molecular weight (= 118) of 1,6-hexanediol.

[0262] Using the calculated content ratio of the amine (unit: mass%) and the following formula, the content ratio in terms of nitrogen atoms of the amine (unit: mass ppm) was calculated.

[0263]

Equation

[0264] Also, regarding the content ratio of the amine in the dihydroxy compound composition containing 1,6 - hexanediol, 1,4 - butanediol, isosorbide or neopentyl glycol as the dihydroxy compound used in the examples, 1 From the H - NMR measurement results, using the integral value of the peak of the proton of the α - methylene group in the amine (6 - amino - 1 - hexanol), the integral value of the peak of the proton of the α - methylene group in each dihydroxy compound, the molecular weight of each dihydroxy compound, and an equation according to the above formula, the content ratio in terms of nitrogen atoms of the amine in the dihydroxy compound composition with respect to 100% of the total mass of the dihydroxy compound composition (unit: mass ppm) was calculated. At that time, "M(14BG)" was used as the molecular weight of 1,4 - butanediol (=90), "M(ISB)" was used as the molecular weight of isosorbide (=146), and "M(NPG)" was used as the molecular weight of neopentyl glycol (=104).

[0265] Also, regarding the content ratio of the amine in the dihydroxy compound composition containing dihexylamine as the amine used in the examples, 1 From the H - NMR measurement results, using the integral value of the peak of the proton of the α - methylene group in the amine, the integral value of the peak of the proton of the α - methylene group in each dihydroxy compound, the molecular weight of each dihydroxy compound, and an equation according to the above formula, the content ratio in terms of nitrogen atoms of the amine in the dihydroxy compound composition with respect to 100% of the total mass of the dihydroxy compound composition (unit: mass ppm) was calculated. At that time, "M(amine)" was used as the molecular weight of dihexylamine (=185).

[0266] <Content ratio of aldehyde> As the dihydroxy compound composition, the content ratio of aldehyde in 1,6 - hexanediol used in the examples and comparative examples was measured according to the following procedure. In this evaluation, the definitions of "aldehyde" and "content ratio of aldehyde" are as described in the above - mentioned explanation of aldehyde.

[0267] 1,6 - hexanediol was dissolved in CDCl3, and using a nuclear magnetic resonance spectrometer (400 MHz, manufactured by JEOL Ltd., model name: ECZ400S), under the conditions of a measurement temperature of 30 °C and an integration number of 32 times, 1 1H - NMR measurement was performed.

[0268] Using the integration values a and b used when calculating the content of the amine, and the integration value c of the 1H proton of the aldehyde group in the aldehyde present at δ 9.80 - 9.75 ppm and the following formula, the content ratio (unit: mass ppm) of the aldehyde with respect to 100% of the total mass of the dihydroxy compound composition containing 1,6 - hexanediol was calculated.

[0269]

Equation

[0270] In the above formula, "M(amine)" represents the molecular weight (= 117) of 6 - amino - 1 - hexanol which is a primary amine, "M(aldehyde)" represents the molecular weight (= 116) of the aldehyde (6 - hydroxyhexanal), and "M(16HD)" represents the molecular weight (= 118) of 1,6 - hexanediol.

[0271] Also, regarding the content ratio of the aldehyde in the dihydroxy compound composition containing 1,6 - hexanediol and 1,4 - butanediol or neopentyl glycol as the dihydroxy compound used in the examples, similarly, 1From the results of \(^1\)H-NMR measurement, the integral value of the peak of the proton of the α-methylene group in the amine (6-amino-1-hexanol), the integral value of the peak of the proton of the aldehyde group in the aldehyde (6-hydroxyhexanal), the integral value of the peak of the proton of the α-methylene group in each dihydroxy compound, the molecular weight of each dihydroxy compound, and using an equation according to the above formula, the content ratio (unit: mass ppm) of aldehyde in the dihydroxy compound composition with respect to 100% of the total mass of the dihydroxy compound composition was calculated. At that time, "M(14BG)" was taken as the molecular weight of 1,4-butanediol (=90), and "M(NPG)" was taken as the molecular weight of neopentyl glycol (=104).

[0272] Also, regarding the content ratio of aldehyde in the dihydroxy compound composition containing dihexylamine as the amine used in the examples, in the same manner, 1 From the results of \(^1\)H-NMR measurement, the integral value of the peak of the proton of the α-methylene group in the amine, the integral value of the peak of the proton of the aldehyde group in the aldehyde (6-hydroxyhexanal), the integral value of the peak of the proton of the α-methylene group in each dihydroxy compound, the molecular weight of each dihydroxy compound, and using an equation according to the above formula, the content ratio (unit: mass ppm) of aldehyde in the dihydroxy compound composition with respect to 100% of the total mass of the dihydroxy compound composition was calculated. At that time, as "M(amine)", the molecular weight of dihexylamine (=185) was used.

[0273] [Evaluation method: Polyurethane] <Mass average molecular weight (Mw) and number average molecular weight (Mn)>[ Regarding the polyurethanes obtained in the examples and comparative examples, the mass average molecular weight (Mw) and the number average molecular weight (Mn) were determined by the following procedure using gel permeation chromatography (GPC measurement). A polyurethane sample was dissolved in dimethylacetamide (containing 0.3 mass% lithium bromide anhydride) so that the polyurethane concentration became 0.07 mass%, and this was used as a sample for GPC measurement. Using a GPC apparatus (manufactured by Tosoh Corporation, model name: HLC-8420, column: 2 pieces of TSKgel SuperAWM-H manufactured by Tosoh Corporation), GPC measurement was performed under the measurement conditions of a sample injection volume of about 40 μL, a column temperature of 40 °C, dimethylacetamide (containing 0.3 mass% lithium bromide anhydride) as a measurement solvent (mobile phase), and a flow rate of 0.6 mL / min. Regarding the molecular weight of the polyurethane, using a commercially available monodisperse polystyrene solution as a standard sample, the number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn) in terms of standard polystyrene were measured.

[0274] <Solution viscosity> The viscosities of the polyurethane solutions obtained in the examples and comparative examples were measured at 40 °C using an E-type viscometer (apparatus name: TV-100EH, cone: 3°×R14, manufactured by Toki Sangyo Co., Ltd.).

[0275] <Mechanical properties> As an index of the mechanical properties of the polyurethane, the tensile test of the polyurethane was performed using the following method, and various mechanical properties were evaluated. The polyurethane solutions obtained in the examples and comparative examples were applied onto a fluororesin sheet (product name: fluorine tape "Nitron 900", manufactured by Nitto Denko Corporation) with a thickness of 0.1 mm using an applicator with a clearance of 500 μm, dried at 80 °C for 1 hour, then at 100 °C for 0.5 hour, and further at 100 °C under vacuum for 1.0 hour to dry and remove the solvent (DMF). After that, it was allowed to stand at 23 °C and 55% RH in a constant temperature and humidity environment for 12 hours or more to obtain a laminated film with a polyurethane layer formed on the surface of the fluororesin sheet. The thickness of the polyurethane layer after drying was 100 μm. After peeling off the polyurethane layer from the obtained laminated film, a strip-shaped polyurethane film (length 150 mm, width 10 mm, thickness 100 μm) was cut out and used as a sample piece for the tensile test.

[0276] (Tensile test) Regarding the above-mentioned specimen for tensile test, in accordance with JIS K6301 (2010), a bench-type precision universal testing machine (manufactured by Shimadzu Corporation, product name: Autograph AGS-X) was used to conduct a tensile test under the conditions of a chuck distance of 50 mm, a tensile speed of 500 mm / min, and a temperature of 23 °C (relative humidity 60%). Measurements were taken using four specimens for the tensile test, and the average value and standard deviation of the 300% modulus, as well as the stress (breaking strength) and elongation (breaking elongation) at the time when the test piece broke, were measured. The following formula was used to calculate the coefficient of variation of the breaking strength and breaking elongation. Coefficient of variation (%) = (standard deviation / average value) × 100

[0277] <Chemical resistance of polyurethane> As an index of the chemical resistance of polyurethane, the mass change rate when polyurethane was immersed in a test solution was measured using the following method. The polyurethane solutions obtained in the examples and comparative examples were applied onto a fluororesin sheet (product name: fluorine tape "Nitron 900", manufactured by Nitto Denko Corporation) with a thickness of 0.1 mm using an applicator with a clearance of 500 μm, dried at 80 °C for 1 hour, then at 100 °C for 0.5 hour, and further at 100 °C under vacuum for 1.0 hour to dry and remove the solvent (DMF), thereby obtaining a laminated film with a polyurethane layer formed on the surface of the fluororesin sheet. The thickness of the polyurethane layer after drying was 100 μm. After peeling off the polyurethane layer from the obtained laminated film, a square-shaped polyurethane film (3 cm in length, 3 cm in width, 100 μm in thickness) was cut out and used as a specimen for the chemical resistance test.

[0278] (Ethanol resistance test) After measuring the weight of the test piece for the chemical resistance test using a precision balance, it was placed in a glass petri dish with an inner diameter of 10 cmφ containing 50 mL of ethanol as the test solvent and immersed at room temperature of about 23°C for 1 hour. After the test, the test piece was taken out, gently wiped on both sides with a paper wiper, and then its mass was measured using a precision balance. The mass change rate (increase rate) was calculated from the mass change of the test piece before and after the test. A mass change rate closer to 0% indicates better ethanol resistance.

[0279] (Ethyl acetate resistance test) After measuring the weight of the test piece for the chemical resistance test using a precision balance, it was placed in a glass petri dish with an inner diameter of 10 cmφ containing 50 mL of ethyl acetate as the test solvent and immersed at room temperature of about 23°C for 20 minutes. After the test, the test piece was taken out, gently wiped on both sides with a paper wiper, and then its mass was measured using a precision balance. The mass change rate (increase rate) was calculated from the mass change of the test piece before and after the test. A mass change rate closer to 0% indicates better ethyl acetate resistance.

[0280] [Raw materials used] The abbreviations of the raw materials used in the examples and comparative examples are as follows. 16HD: 1,6 - hexanediol (manufactured by BASF Japan Ltd.) 14BG: 1,4 - butanediol (manufactured by Mitsubishi Chemical Corporation) ISB: Isosorbide (manufactured by Rocket Co., Ltd.) NPG: Neopentyl glycol (manufactured by Mitsubishi Gas Chemical Company, Inc.) 6 - Amino - 1 - hexanol (manufactured by Tokyo Chemical Industry Co., Ltd.) Dihexylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) DPC: Diphenyl carbonate (manufactured by Mitsubishi Chemical Corporation) Mg catalyst: Magnesium acetate tetrahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) MDI: Diphenylmethane diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) U - 830: Dioctyltin monodecanoate (trade name: Neostan U - 830, manufactured by Nitto Kasei Co., Ltd.) DMF: Dehydrated N,N-dimethylformamide (manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0281] [Production and Evaluation of Polycarbonate Diol] [Example 1] Into a 1 L glass separable flask equipped with a stirrer, a distillate trap, and a pressure regulator, 323 g of 1,6-hexanediol containing 0.6 g of 6-amino-1-hexanol as the raw material dihydroxy compound composition, 527 g of DPC as the carbonate compound, and 1.4 mL of an Mg catalyst aqueous solution (concentration: 8.4 g / L - magnesium acetate tetrahydrate) as the transesterification reaction catalyst were introduced. After replacing the inside of the flask with a nitrogen atmosphere, while stirring the contents of the flask, the temperature of the contents was gradually increased by heating until it reached 160 °C to dissolve the contents by heating. The pressure inside the flask at this time was 101 kPa. Then, after gradually reducing the pressure inside the flask from 101 kPa to 24 kPa over 2 minutes, while removing the generated phenol out of the reaction system, the reaction was carried out for 90 minutes. Next, after gradually reducing the pressure inside the flask to 9.3 kPa over 90 minutes, and then further gradually reducing the pressure to 0.7 kPa over 30 minutes to continue the reaction, the temperature of the contents was increased until it reached 170 °C, and while removing phenol and unreacted dihydroxy compound out of the reaction system, the reaction was carried out for another 120 minutes. Then, the temperature of the contents was allowed to cool to room temperature to obtain 368 g of a polycarbonate diol-containing composition. The obtained polycarbonate diol was designated as "PCD2".

[0282] [Comparative Example 1] In Example 1, the reaction was carried out under the same conditions as in Example 1, except that 323 g of 1,6-hexanediol not containing 6-amino-1-hexanol was used as the raw material dihydroxy compound composition. The obtained polycarbonate diol was designated as "PCD1". The evaluation results of this PCD1 are shown in Table 1.

[0283] [Example 2] In Example 1, the reaction was carried out under the same conditions as in Example 1, except that 16HD containing 6-amino-1-hexanol in the amount described in Table 1 was used as the starting dihydroxy compound composition. The obtained polycarbonate diol was designated as "PCD3". The evaluation results of this PCD3 are shown in Table 1.

[0284] <Example 3> In Example 1, the reaction was carried out under the same conditions as in Example 1, except that 16HD containing 6-amino-1-hexanol in the amount described in Table 1 was used as the starting dihydroxy compound composition. The obtained polycarbonate diol was designated as "PCD4". The evaluation results of this PCD4 are shown in Table 1.

[0285] <Example 4> In Example 1, as the starting dihydroxy compound composition, 16HD and 14BG containing 6-amino-1-hexanol in the amount described in Table 1 were used, and the reaction was carried out under the same conditions as in Example 1, except that the 16HD, the 14BG, DPC, and the Mg catalyst aqueous solution were charged in the amounts shown in Table 1. The obtained copolymer polycarbonate diol was designated as "PCD5". The evaluation results of this PCD5 are shown in Table 1.

[0286] <Example 5> In Example 1, as the starting dihydroxy compound composition, 16HD and ISB containing 6-amino-1-hexanol in the amount described in Table 1 were used, and the reaction was carried out under the same conditions as in Example 1, except that the 16HD, the ISB, DPC, and the Mg catalyst aqueous solution were charged in the amounts shown in Table 1. The obtained copolymer polycarbonate diol was designated as "PCD6". The evaluation results of this PCD6 are shown in Table 1.

[0287] <Example 6> In Example 1, as the raw material dihydroxy compound composition, 16HD and ISB containing 6-amino-1-hexanol in the amounts shown in Table 1 were used, and the reaction was carried out under the same conditions as in Example 1 except that the 16HD, the ISB, DPC, and the aqueous Mg catalyst solution were charged in the amounts shown in Table 1. The obtained copolymer polycarbonate diol was designated as "PCD7". The evaluation results of this PCD7 are shown in Table 1.

[0288]

Table 1

[0289] The polycarbonate diols obtained in Examples 1 to 6 all had a color tone (APHA) of 70 or less, which was an industrially acceptable level.

[0290] [Production and Evaluation of Polyurethane] <Purification of Polycarbonate Diol> To remove the phenol contained in the polycarbonate diols (PCD1 to 4) obtained in Comparative Example 1 and Examples 1 to 3, first, 0.3 g of a 0.85 mass% phosphoric acid aqueous solution was added to 220 g of the polycarbonate diol to deactivate magnesium acetate. Then, it was fed to a thin-film distillation apparatus at a flow rate of 20 g / min, and thin-film distillation (temperature: 180 to 190 °C, pressure: 40 to 67 Pa) was carried out. As the thin-film distillation apparatus, a molecular distillation apparatus MS-300 special type manufactured by Shibata Scientific Co., Ltd. with an internal condenser having a diameter of 50 mm, a height of 200 mm, and an area of 0.0314 m 2 was used. Hereinafter, the PCD1 to 4 after thin-film distillation are referred to as PCD1A to 4A, respectively. The content ratios of amine-derived structural units in the PCD1A to 4A obtained by thin-film distillation are shown in Table 2.

[0291] <Comparative Example 1-2> Into a separable flask equipped with a thermocouple and a cooling tube, 69.8 g of PCD1A preheated to 80 °C, 6.30 g of 14BG as a chain extender, 0.02 g of U-830 as a catalyst, and 239 g of DMF as a reaction solvent were added. The flask was immersed in an oil bath set at 55 °C and stirred and mixed at a stirring speed of 60 rpm until uniform. The moisture content of the reaction solution in the flask was measured, and the amount of MDI consumed by the moisture was calculated. Also, the sampled and withdrawn amount was recorded, and the charged amounts of each raw material were corrected. To the reaction solution, MDI equivalent to an NCO / OH molar ratio = 0.900 (including moisture correction) as an isocyanate compound was added in a solid state using a funnel, and stirred and mixed at a stirring speed of 60 rpm until uniform. In this specification, the "NCO / OH molar ratio" refers to the ratio (molar ratio) of the total amount of the substance of MDI (number of moles) to the value obtained by subtracting the total amount of the substance of contained moisture (number of moles) from the total amount of the substance of polycarbonate diol and 14BG (number of moles) at the time of MDI addition. An exothermic peak accompanied by a temperature rise of +10 to 15 °C in the reaction solution temperature was confirmed immediately after MDI addition. After the exothermic peak subsided, the temperature of the oil bath was set to 70 °C and heated up 5 minutes later. One hour after adding MDI, the molecular weight of the polyurethane in the reaction solution was measured to confirm whether it reached the target molecular weight (in the range of MW = 170000 to 180000). If it did not reach the target, MDI equivalent to NCO / OH = 0.005 to 0.015 was additionally added, and the reaction was continued for at least 30 minutes. Then, the molecular weight of the polyurethane in the reaction solution was measured. The additional addition of MDI and the measurement of the molecular weight were repeated until the target Mw was reached. Finally, a polyurethane solution containing polyurethane with Mw = 170032 was obtained at a total NCO / OH = 0.990. The evaluation results of the obtained polyurethane solution are shown in Table 2.

[0292] <Example 1-2> In Comparative Examples 1-2, polyurethane polymerization was carried out under the same conditions and by the same method as in Comparative Examples 1-2, except that PCD2A was used instead of PCD1A and the charged amounts of each raw material were changed to the charged amounts described in Table 2, respectively, to obtain a polyurethane solution. The evaluation results of the obtained polyurethane solution are shown in Table 2.

[0293] <Example 2-2> In Comparative Examples 1-2, polyurethane polymerization was carried out under the same conditions and by the same method as in Comparative Examples 1-2, except that PCD3A was used instead of PCD1A and the charged amounts of each raw material were changed to the charged amounts described in Table 2, respectively, to obtain a polyurethane solution. The evaluation results of the obtained polyurethane solution are shown in Table 2.

[0294] <Example 3-2> In Comparative Examples 1-2, polyurethane polymerization was carried out under the same conditions and by the same method as in Comparative Examples 1-2, except that PCD4A was used instead of PCD1A and the charged amounts of each raw material were changed to the charged amounts described in Table 2, respectively, to obtain a polyurethane solution. The evaluation results of the obtained polyurethane solution are shown in Table 2.

[0295]

Table 2

[0296] It can be seen from Table 2 as follows. The polyurethanes obtained in Examples 1-2 to 3-2 were excellent in mechanical properties without impairing chemical resistance and had a small variation (coefficient of variation) in the mechanical properties compared with the polyurethanes obtained in Comparative Examples 1-2. On the other hand, since the polycarbonate diol used as a raw material in Comparative Examples 1-2 did not contain an amine-derived structural unit, the breaking strength was lower than that in Examples 1-2 to 3-2, and the variation (coefficient of variation) in the mechanical properties was large. From the above, it can be understood that according to the polycarbonate diol of the present invention, a polyurethane having excellent mechanical properties, suppressed variation in the mechanical properties, and good chemical resistance can be obtained.

[0297] In addition, when the content of the structural unit (2) contained in the polycarbonate diol is 80 mass ppm or less in terms of nitrogen atom with respect to the total mass of the polycarbonate diol, the following Examples and Comparative Examples show that the more the content of the structural unit (2), the more the coloring of the polycarbonate diol can be suppressed and the color tone can be controlled well.

[0298] [Comparative Example 2] 16HD100 g was heat-treated at 130°C for 3 hours in air to oxidize a part of 16HD to obtain a dihydroxy compound composition as 6-hydroxyhexanal, which was designated as HD(1). The contents of amine and aldehyde in HD(1) are shown in Table 3.

[0299] Into a 0.5 L separable glass flask equipped with a stirrer, a distillate trap, and a pressure regulator, 96 g of HD(1) as a dihydroxy compound composition, 154 g of DPC as a carbonate compound, and 0.4 mL of an Mg catalyst aqueous solution (concentration: 8.4 g / L - magnesium acetate tetrahydrate) as a transesterification reaction catalyst were charged. After replacing the inside of the flask with a nitrogen atmosphere, while stirring the contents inside the flask, the temperature of the contents was heated and raised until it reached 160 °C, and the contents were heated and dissolved. The pressure inside the flask at this time was 101 kPa. Then, after gradually reducing the pressure inside the flask from 101 kPa to 24 kPa over 2 minutes, while removing the generated phenol out of the reaction system, the reaction was carried out for 90 minutes. Next, after gradually reducing the pressure inside the flask to 9.3 kPa over 90 minutes, and then further gradually reducing the pressure to 0.7 kPa over 30 minutes and continuing the reaction, the temperature of the contents was raised until it reached 170 °C, while removing phenol and unreacted dihydroxy compound out of the reaction system, and the reaction was further carried out for 90 minutes. Then, the temperature of the contents was allowed to cool to room temperature, and 114 g of polycarbonate diol was obtained. The evaluation results of the obtained polycarbonate diol are shown in Table 3.

[0300] [Example 7] 0.01 g of 6-amino-1-hexanol as an amine was added to 100 g of 16HD, and the mixture was heat-treated at 130 °C in air for 3 hours to oxidize a part of 16HD to obtain HD(2) as 6-hydroxyhexanal. The amine and aldehyde contents in HD(2) are shown in Table 3.

[0301] The synthesis of polycarbonate diol was carried out under the same conditions as in Comparative Example 2, except that HD(2) was used instead of HD(1) used in Comparative Example 2, and polycarbonate diol was obtained. The evaluation results of the obtained polycarbonate diol are shown in Table 3.

[0302] [Comparative Example 3] 150 g of 16HD was heat-treated at 130 °C in air for 3 hours to oxidize a part of 16HD to obtain a 16HD composition as 6-hydroxyhexanal, which was designated as HD(3). A dihydroxy compound composition (16HD composition) was obtained by mixing HD(3) and 14BG in the amounts shown in Table 3, and this was designated as HD(3-1). The amine content and aldehyde content in the HD(3-1) are shown in Table 3.

[0303] The synthesis of the polycarbonate diol was carried out under the same conditions as in Comparative Example 2, except that HD(3-1) was used instead of HD(1) used in Comparative Example 2, and the blending amounts of the 16HD composition and the carbonate compound were as shown in Table 3, to obtain a polycarbonate diol. The evaluation results of the obtained polycarbonate diol are shown in Table 3.

[0304] [Examples 8 to 10] The amines shown in Table 3 were added to 150 g of 16HD in the addition amounts shown in Table 3, and the mixture was heated at 130°C in air for 3 hours to oxidize a part of the 16HD to obtain a 16HD composition having 6-hydroxyhexanal, which was designated as HD(4) to HD(6). HD(4) to HD(6) and 14BG were mixed in the blending amounts shown in Table 3 to obtain dihydroxy compound compositions (16HD compositions), which were designated as HD(4-1) to HD(6-1), respectively. The amine content and aldehyde content in HD(4-1) to HD(6-1) are shown in Table 3.

[0305] The synthesis of the polycarbonate diol was carried out under the same conditions as in Comparative Example 2, except that HD(4-1) to HD(6-1) were used instead of HD(1) used in Comparative Example 2, and the blending amounts of the 16HD composition and the carbonate compound were as shown in Table 3, to obtain a polycarbonate diol. The evaluation results of the obtained polycarbonate diol are shown in Table 3.

[0306] [Example 11] As an amine, 0.02 g of dihexylamine was added to 150 g of 1,6-hexanediol (16HD), and the mixture was heated at 130 °C in air for 3 hours to oxidize a part of 16HD to obtain a dihydroxy compound composition (16HD composition) containing 6-hydroxyhexanal, which was designated as HD(7). A dihydroxy compound composition obtained by mixing HD(7) and NPG in the amounts shown in Table 3 was designated as HD(7-1). The amine content and aldehyde content in the HD(7-1) are shown in Table 3.

[0307] For the synthesis of polycarbonate diol, using HD(7-1) instead of HD(1) used in Comparative Example 2, and setting the blending amounts of the 16HD composition and the carbonate compound as shown in Table 3, the reaction was carried out under the same conditions as in Comparative Example 2 to obtain polycarbonate diol. The evaluation results of the obtained polycarbonate diol are shown in Table 3.

[0308]

Table 3

[0309] From Examples 7 to 11 and Comparative Examples 2 to 3, it can be seen that by adding an amine to the dihydroxy compound (16HD), the aldehyde content in the dihydroxy compound composition after heat treatment was reduced. In addition, the polycarbonate diol obtained in the examples had a low aldehyde content, and the color tone (APHA) in terms of coloring was better than that of the comparative examples, and it was at an industrially acceptable level. From these results, it can be seen that when the amine content (in terms of nitrogen atoms) is 100 mass ppm or less during the production of polycarbonate diol, the aldehyde content in the dihydroxy compound composition after heat treatment can be reduced. Furthermore, the content of the amine-derived structural unit (in terms of nitrogen atoms) in the obtained polycarbonate diol is 80 mass ppm or less, and since the aldehyde content in the polycarbonate diol can be reduced, it can be seen that the coloring of the polycarbonate diol can be suppressed and the color tone is good.

[0310] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made within the scope in which the effects of the invention are achieved. This application is based on Japanese Patent Application No. 2023-018540 filed on February 9, 2023, Japanese Patent Application No. 2023-042052 filed on March 16, 2023, and Japanese Patent Application No. 2023-136449 filed on August 24, 2023, the entire contents of each of which are incorporated herein by reference.

Claims

1. containing a structural unit (1) represented by the following general formula (I) and a structural unit (2) represented by the following general formula (II), in the polycarbonate diol, the content of the structural unit (2) is 1 mass ppm or more and 1200 mass ppm or less in terms of nitrogen atom relative to the total mass of the polycarbonate diol, a polycarbonate diol, wherein the structural unit (1) contains a structural unit (1a) represented by the following general formula (Ia). 【Chemical 1】 (In the above general formula (I), R represents a hydrocarbon group having 2 to 20 carbon atoms which may have a substituent or a hetero atom.) [Chemical 2] (In the above general formula (II), m is an integer of 2 to 20. R ２ represents an alkyl group having 1 to 20 carbon atoms or a hydrogen atom, which may have a substituent.) [Chemical Formula 3] (In the above general formula (Ia), n is an integer of 2 to 20.)

2. The polycarbonate diol according to claim 1, wherein the structural unit (2) is a structural unit derived from at least one amine selected from a primary amine (2-1) and a secondary amine (2-2).

3. The polycarbonate diol according to claim 1, wherein the structural unit (2) contains a structural unit derived from at least one amine selected from 6-amino-1-hexanol, 6-methylamino-1-hexanol, and 6-ethylamino-1-hexanol.

4. The polycarbonate diol according to claim 1, wherein the content of the structural unit (2) contained in the polycarbonate diol is 80 mass ppm or less in terms of nitrogen atom relative to the total mass of the polycarbonate diol.

5. The polycarbonate diol according to claim 4, wherein the polycarbonate diol further contains an aldehyde.

6. The polycarbonate diol according to claim 1, wherein the number average molecular weight (Mn) of the polycarbonate diol is 250 or more and 5000 or less.

7. A dihydroxy compound composition containing an amine and a dihydroxy compound (1) represented by the following general formula (I-1), and a carbonate compound are polycondensed by a transesterification reaction in the presence of a catalyst to obtain a polycarbonate diol containing a structural unit (2) represented by the following general formula (II), in the dihydroxy compound composition, the content of the amine is 1 mass ppm or more and 1500 mass ppm or less in terms of nitrogen atom relative to the total mass of the dihydroxy compound composition, The content of the structural unit (2) contained in the polycarbonate diol is 1 mass ppm or more and 1200 mass ppm or less in terms of nitrogen atom relative to the total mass of the polycarbonate diol. The method for producing a polycarbonate diol, wherein the dihydroxy compound (1) contains a compound represented by the following general formula (Ia-1). 【Chemical Formula 4】 (In the general formula (I-1), R is a hydrocarbon group having 2 to 20 carbon atoms which may have a substituent or a hetero atom.) 【Chemical Formula 5】 (In the above general formula (II), m is an integer of 2 to 20. R ２ represents an alkyl group having 1 to 20 carbon atoms or a hydrogen atom which may have a substituent.) 【Chemical Formula 6】 (In the above general formula (Ia-1), n is an integer of 2 to 20.)

8. The method for producing a polycarbonate diol according to claim 7, wherein the polycarbonate diol contains a structural unit (1) represented by the following general formula (I). 【Chemical Formula 7】 (In the above general formula (I), R is a hydrocarbon group having 2 to 20 carbon atoms which may have a substituent or a hetero atom.)

9. The method for producing a polycarbonate diol according to claim 7, wherein the amine contains at least one selected from a primary amine (2-1) and a secondary amine (2-2).

10. The method for producing a polycarbonate diol according to claim 7, wherein the amine contains at least one selected from 6-amino-1-hexanol, 6-methylamino-1-hexanol, and 6-ethylamino-1-hexanol.

11. The method for producing a polycarbonate diol according to claim 7, wherein the content of the amine in the dihydroxy compound composition is 100 mass ppm or less in terms of nitrogen atom relative to the total mass of the dihydroxy compound composition.

12. The method for producing a polycarbonate diol according to claim 11, wherein the dihydroxy compound composition further contains an aldehyde.

13. The method for producing a polycarbonate diol according to claim 7, wherein the content of the structural unit (2) contained in the polycarbonate diol is 80 mass ppm or less in terms of nitrogen atom relative to the total mass of the polycarbonate diol.

14. The method for producing a polycarbonate diol according to claim 13, wherein the polycarbonate diol further contains an aldehyde.

15. A polyurethane obtained by using the polycarbonate diol according to claim 1.

16. The polyurethane according to claim 15, which is used in any one selected from the group consisting of an active energy ray-curable polymer composition, artificial leather, synthetic leather, paint, coating agent, elastic fiber, adhesive, and adhesive.

Images