Method for producing polycarbonate diol and polycarbonate diol

Abstract

To provide a method for producing a polycarbonate diol efficiently (specifically, for example, under milder reaction conditions and in a shorter time).SOLUTION: There is provided a method for producing a polycarbonate diol, which comprises a step of obtaining a polycarbonate diol by polycondensation through an ester exchange reaction in the presence of an ester exchange catalyst, using a dihydroxy compound and a carbonate ester as the raw material monomers, wherein the ester exchange catalyst includes an ester exchange catalyst A1 containing at least one metal (M1) selected from the group consisting of metals of group 6, 7, 8, 9, 10 and 11 of the long periodic table and an ester exchange catalyst A2 containing at least one metal (M2) selected from the group consisting of metals of group 2 of the long periodic table.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Conventionally, polyurethane resins and polyurea resins have been used in a wide range of fields such as synthetic leather, artificial leather, adhesives, furniture paints, and automotive paints. Polyethers and polyesters are used as the polyol component that reacts with isocyanate (see, for example, Patent Document 1 and Non-Patent Document 1). However, in recent years, the requirements for resin resistance, such as heat resistance, weather resistance, hydrolysis resistance, mildew resistance, and oil resistance, have become more demanding.

[0003] In order to meet such high performance requirements, various polycarbonate diols have been proposed as soft segments having excellent hydrolysis resistance, light resistance, oxidation degradation resistance, heat resistance, etc. (see, for example, Patent Documents 2 to 5).

[0004] For the production of these polycarbonate diols, a transesterification catalyst is usually used. For example, in the production of a copolymer polycarbonate diol of diethyl carbonate and 1,6-hexanediol and 1,5-pentanediol, metallic sodium is used as a catalyst (see, for example, Patent Document 6), and in combinations with diols such as diethyl carbonate and 1,3-propanediol, 2-methyl-1,3-propanediol, and 1,3-butanediol, sodium ethoxide or magnesium acetate is used as a catalyst (see, for example, Patent Document 7).

[0005] Furthermore, lead acetate and tetra-n-butyl titanate are used as catalysts in the production of copolymer polycarbonate diols with ethylene carbonate and diols such as 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 2-methyl-1,3-propanediol, while tetra-n-butyl titanate is used as a catalyst in the production of polycarbonate diols with ethylene carbonate and various alkylenediols and oxyalkylenediols such as diethylene glycol and dibutylene glycol (see, for example, Patent Document 8).

[0006] Historically, in combinations of ethylene carbonate and 1,6-hexanediol, catalysts such as tetra-n-butyl titanate, dibutyltin dilaurate, sodium acetate, lithium hydroxide, and tin powder have been used (see, for example, Patent Document 9).

[0007] Furthermore, magnesium acetate has been successfully used as a catalyst in the production of copolymer polycarbonate diols with diphenyl carbonate and 1,6-hexanediol and neopentyl glycol (see, for example, Patent Document 10).

[0008] Furthermore, in recent years, a method for producing polycarbonate diols has been disclosed that involves using a salt (or a salt with an acetylacetone derivative) of at least one metal selected from the group consisting of zinc and metals of Group 2 of the long-period periodic table as a catalyst to improve the color tone of polycarbonate diols under milder conditions (see, for example, Patent Document 11). [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2000-95836 [Patent Document 2] Japanese Patent Publication No. 2001-123112 [Patent Document 3] Japanese Patent Application Publication No. 5-51428 [Patent Document 4] Japanese Patent Application Publication No. 6-49166 [Patent Document 5] International Publication No. 2002 / 070584 [Patent Document 6] Japanese Patent Application Publication No. 2-289616 [Patent Document 7] Japanese Patent Publication No. 2012-46659 [Patent Document 8] International Publication No. 2006 / 088152 [Patent Document 9] Japanese Patent Application Publication No. 51-144492 [Patent Document 10] Japanese Patent Publication No. 2013-010950 [Patent Document 11] Japanese Patent Publication No. 2020-125467 [Non-patent literature]

[0010] [Non-Patent Document 1] "Fundamentals and Applications of Polyurethane," pp. 96-106, supervised by Katsuji Matsunaga, CMC Publishing Co., Ltd., published November 2006. [Overview of the project] [Problems that the invention aims to solve]

[0011] Conventional techniques require high reaction temperatures or the addition of large amounts of catalyst to carry out polycondensation reactions of dihydroxy compounds with varying reactivity, which can lead to discoloration and thermal degradation of aliphatic polycarbonates. Therefore, there is room for improvement in transesterification catalysts known in this field when it comes to the production of various polycarbonate diols.

[0012] For example, using strong bases such as alkali metals, alkaline earth metals, or their alkoxides as catalysts tends to cause discoloration of polycarbonate diols.

[0013] In addition, when using a titanium compound as a catalyst, since the activity of the catalyst is not sufficient, it tends to take a long time to produce polycarbonate diol. When the reaction time is long, the formation of undesirable ether groups and vinyl groups is promoted. These groups can cause deterioration of the weather resistance and heat resistance of the polyurethane obtained when using polycarbonate diol as a polyurethane raw material, and thus are not preferable as a polyurethane raw material.

[0014] On the other hand, in recent years, the harmfulness to the human body and the adverse effects on the ecosystem of lead compounds and organotin compounds have been revealed. Therefore, these compounds are not preferable as components remaining in polycarbonate diol.

[0015] Also, when using magnesium acetate, magnesium alkoxide, or magnesium acetylacetone as a catalyst, the polymerization activity is higher than that of titanium compounds and an improvement in productivity can be seen, but it is not sufficient. Therefore, there is room for improvement in terms of the coloring of the obtained polycarbonate diol and the improvement of productivity.

[0016] Therefore, an object of the present invention is to provide a method for efficiently producing polycarbonate diol (specifically, for example, under milder reaction conditions and in a short time). Also, preferably, an object is to provide a polycarbonate diol having excellent color tone, few ether bonds, and high purity of terminal primary hydroxyl groups (OH), and a polyurethane excellent in chemical resistance, heat resistance, and hydrolysis resistance using the polycarbonate diol.

Means for Solving the Problems

[0017] The inventors of the present invention have conducted extensive research to solve these problems and have found that by using at least two transesterification catalysts containing specific metals when producing polycarbonate diols by polycondensation of a dihydroxy compound and a carbonate ester as raw material monomers via a transesterification reaction, polycarbonate diols can be efficiently produced, thereby solving the above problems. Furthermore, the inventors have found a polycarbonate diol that preferably has excellent color tone, few ether bonds, and high purity of terminal primary hydroxyl groups (OH), and a polyurethane using this polycarbonate diol that has excellent chemical resistance, heat resistance, and hydrolysis resistance.

[0018] In other words, the gist of the present invention is as follows: [1] The process includes a step of obtaining a polycarbonate diol by polycondensation of a dihydroxy compound and a carbonate ester as raw material monomers in the presence of a transesterification catalyst via a transesterification reaction. A method for producing a polycarbonate diol, comprising: transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table; and transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals from group 2 of the long-period periodic table. [2] A method for producing a polycarbonate diol according to [1], wherein the transesterification catalyst A1 is at least one metal complex and / or a hydrate thereof represented by the following formula (1). [ka] (In the formula, R1 and R3 each independently represent a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon groups of R1 and R3 may be substituted with halogen atoms or may have oxygen atoms; R2 represents hydrogen, a halogen atom, or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R2 may be substituted with halogen atoms or may have oxygen atoms; M1 represents at least one metal selected from the group consisting of metals in groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table, and n is 1, 2, or 3.) [3] A method for producing a polycarbonate diol according to [1], wherein the transesterification catalyst A1 is a salt and / or hydrate thereof of at least one carboxylic acid represented by the following formula (2) and at least one metal (M1) selected from the group consisting of metals of groups 6, 7, 8, 9, 10 and 11 of the long-period periodic table. [ka] (In the formula, R4 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R4 may be substituted with a halogen atom or may have an oxygen atom.) [4] A method for producing a polycarbonate diol according to any one of [1] to [3], wherein the metal (M1) is at least one metal selected from the group consisting of molybdenum, manganese, iron, cobalt, nickel, and copper. [5] A method for producing a polycarbonate diol according to any one of [1] to [4], wherein the metal (M1) is manganese. [6] A method for producing a polycarbonate diol according to any one of [1] to [5], wherein the transesterification catalyst A2 is at least one metal complex and / or a hydrate thereof represented by the following formula (3). [ka] (In the formula, R5 and R7 each independently represent a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon groups of R5 and R7 may be substituted with halogen atoms or may have oxygen atoms; R6 represents hydrogen, a halogen atom, or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R6 may be substituted with halogen atoms or may have oxygen atoms; M2 represents at least one metal selected from the group consisting of metals in Group 2 of the long-period periodic table, and n is 1, 2, or 3.) [7] A method for producing a polycarbonate diol according to any one of [1] to [5], wherein the transesterification catalyst A2 is a salt and / or hydrate thereof of at least one carboxylic acid represented by the following formula (4) and at least one metal (M2) selected from the group consisting of metals of Group 2 of the long-period periodic table. [ka] (In the formula, R8 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R8 may be substituted with a halogen atom or may have an oxygen atom.) [8] A method for producing a polycarbonate diol according to any one of [1] to [5], wherein the transesterification catalyst A2 is an alkoxide of at least one alcohol represented by the following formula (5) and at least one metal (M2) selected from the group consisting of metals of Group 2 of the long-period periodic table. [ka] (In the formula, R9 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R9 may be substituted with a halogen atom or may have an oxygen atom.) [9] A method for producing a polycarbonate diol according to any one of [1] to [8], wherein the metal (M2) is at least one metal selected from the group consisting of magnesium and calcium.

[10] A method for producing a polycarbonate diol according to any one of [1] to [9], wherein the metal (M2) is calcium.

[11] The amount of transesterification catalyst A1, as the total amount of the metal (M1), is 0.5 ppm or more and 20 ppm or less relative to the total amount of the dihydroxy compound and carbonate ester. A method for producing a polycarbonate diol according to any one of [1] to

[10] , wherein the amount of transesterification catalyst A2 is 0.25 ppm or more and 10 ppm or less as the total amount of the metal (M2) relative to the total amount of the dihydroxy compound and the carbonate ester.

[12] A method for producing a polycarbonate diol according to any one of [1] to

[11] , wherein the dihydroxy compound comprises at least one selected from the group consisting of aliphatic dihydroxy compounds having a structure represented by the following formula (6). [ka] (In the formula, R 10 (This represents a divalent aliphatic hydrocarbon with 2 to 20 carbon atoms.)

[13] A method for producing a polycarbonate diol according to any one of [1] to

[12] , wherein the carbonate ester is at least one selected from the group consisting of alkylene carbonates, dialkyl carbonates, and diaryl carbonates.

[14] It is a polycondensate resulting from a transesterification reaction between a dihydroxy compound and a carbonate ester. The number-average molecular weight is between 250 and 100,000. The polycarbonate diol contains at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table, in a total amount of 1 ppm to 25 ppm, and at least one metal (M2) selected from the group consisting of metals from group 2 of the long-period periodic table, in a total amount of 0.5 ppm to 12.5 ppm. The Hazen color count measured in accordance with JIS-K0071-1 (1998) is 50 or less. The amount of ether bonded material is 5 mol% or less. A polycarbonate diol with a terminal primary hydroxyl group (OH) purity of 97% or higher.

[15] The polycarbonate diol according to

[14] , wherein metal (M1) is at least one metal selected from the group consisting of molybdenum, manganese, iron, cobalt, nickel, and copper, and metal (M2) is at least one metal selected from the group consisting of magnesium and calcium.

[16] The polycarbonate diol according to

[14] or

[15] , wherein metal (M1) is manganese and metal (M2) is calcium.

[17] Polyurethane containing high-density units derived from any one of the polycarbonate diols described in

[14] to

[16] . [Effects of the Invention]

[0019] The present invention provides a method for producing polycarbonate diols that allows for the efficient production of polycarbonate diols under milder conditions than those of previously known techniques. Furthermore, the present invention preferably provides a polycarbonate diol with excellent color tone, few ether bonds, and high purity of terminal primary hydroxyl groups (OH), as well as a polyurethane using the polycarbonate diol that exhibits excellent chemical resistance, heat resistance, and hydrolysis resistance. [Modes for carrying out the invention]

[0020] The following describes in detail embodiments for carrying out the present invention (hereinafter abbreviated as "this embodiment"). It should be noted that the present invention is not limited to the following embodiments, and can be implemented in various modifications within the scope of its gist.

[0021] [1. Method for producing polycarbonate diol] The method for producing polycarbonate diol in this embodiment includes the step of using a dihydroxy compound and a carbonate ester as raw material monomers and polycondensing them by a transesterification reaction in the presence of a transesterification catalyst to obtain a polycarbonate diol. The transesterification catalyst includes transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table, and transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals from group 2 of the long-period periodic table.

[0022] The method for producing polycarbonate diols in this embodiment, by using at least two transesterification catalysts containing specific metals, allows for the efficient production of polycarbonate diols (specifically, for example, under milder reaction conditions and in a shorter time).

[0023] <1-1. Raw material monomers> The method for producing polycarbonate diol in this embodiment uses a dihydroxy compound and a carbonate ester as raw material monomers.

[0024] <1-1-1. Dihydroxy Compounds> In the method for producing polycarbonate diol of this embodiment, the dihydroxy compound that serves as the raw material monomer is not particularly limited, but for example, linear terminal dihydroxy compounds such as ethylene glycol, 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 and 1,20-eicosanediol; dihydroxy compounds having an ether group such as diethylene glycol, triethylene glycol, tetraethylene glycol, polypropylene glycol and polytetramethylene glycol; thioetherdiols such as bishydroxyethyl thioether; 2-ethyl-1,6-hexanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol and 2,4-diethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (hereinafter sometimes abbreviated as neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol and 2-pentyl-2-propyl-1,3-propanediol, etc. 2,2-dialkyl-substituted 1,3-propanediol Propanediols (hereinafter sometimes referred to as 2,2-dialkyl-1,3-propanediols); tetraalkyl-substituted alkylenediols such as 2,2,4,4-tetramethyl-1,5-pentanediol and 2,2,9,9-tetramethyl-1,10-decanediol; dihydroxy compounds containing cyclic groups such as 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane;Branched-chain dihydroxy compounds such as 2,2-diphenyl-1,3-propanediol, 2,2-divinyl-1,3-propanediol, 2,2-diethynyl-1,3-propanediol, 2,2-dimethoxy-1,3-propanediol, bis(2-hydroxy-1,1-dimethylethyl) ether, bis(2-hydroxy-1,1-dimethylethyl) thioether, and 2,2,4,4-tetramethyl-3-cyano-1,5-pentanediol; 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 4,4-dicyclohexyldimethylmethanediol, 2,2'-bis(4-hydroxycyclohexyl)propane, 1,4-di Dihydroxy compounds containing intramolecular cyclic groups such as hydroxyethylcyclohexane, isosorbide, spiroglycol, 2,5-bis(hydroxymethyl)tetrahydrofuran, 4,4'-isopropylidenedicyclohexanol, and 4,4'-isopropylidenebis(2,2'-hydroxyethoxycyclohexane); dihydroxy compounds having aromatic rings such as 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy-2-methyl)phenyl)fluorene, nitrogen-containing dihydroxy compounds such as diethanolamine and N-methyldiethanolamine; and sulfur-containing dihydroxy compounds such as bis(hydroxyethyl)sulfide;2,2-bis(4-hydroxyphenyl)propane [=bisphenol A], 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxyphenyl)pentane, 2,4'-dihydroxy-diphenylmethane, bis(4-hydroxyphenyl)methane, bis(4-hydroxy-5-nitrophenyl)methane, 1,1-bis Examples include aromatic bisphenols such as s(4-hydroxyphenyl)ethane, 3,3-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenylsulfone, bis(4-hydroxyphenyl)sulfide, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether, 9,9-bis(4-hydroxyphenyl)fluorene, and 9,9-bis(4-hydroxy-2-methylphenyl)fluorene.

[0025] In particular, from the viewpoint of weather resistance of the polyurethane obtained using the polycarbonate diol of this embodiment, it is preferable that the dihydroxy compound is at least one compound selected from the group consisting of aliphatic dihydroxy compounds represented by the following formula (6). [ka] (In the formula, R 10 This represents a divalent aliphatic hydrocarbon with 2 to 20 carbon atoms. Aliphatic hydrocarbons include linear, branched, cyclic, or combinations thereof.

[0026] Among such dihydroxy compounds, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, 1,4-cyclohexanedimethanol, and tricyclodecanedimethanol are particularly preferred.

[0027] These dihydroxy compounds may be used individually or in combination of two or more, depending on the required performance of the resulting polycarbonate diol, but it is preferable to combine multiple compounds to form a copolymerized polycarbonate diol. Copolymerized polycarbonate diols generally have inhibited crystallization, and compared to homopolycarbonate diols, they have higher fluidity, which not only makes them easier to handle when processed into polyurethane, but also imparts flexibility and texture to the polyurethane.

[0028] The copolymer composition ratio is such that, for example, when using two types of dihydroxy compounds, it is preferable to use each dihydroxy compound in an amount of 5 mol% or more, preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, relative to the total dihydroxy compounds.

[0029] Normally, copolymerizing dihydroxy compounds with different molecular structures can lead to heterogeneous polymerization or inhibition of polymerization due to differences in reactivity. However, according to this embodiment, which uses a specific transesterification catalyst described later, copolymerized polycarbonate diols can be easily obtained.

[0030] <1-1-2. Carbonate esters> In the method for producing polycarbonate diol according to this embodiment, the carbonate ester that can be used as a raw material monomer is not limited as long as the effects of the present invention are not lost, but examples include dialkyl carbonates, diaryl carbonates, or alkylene carbonates.

[0031] Among the carbonate esters that can be used in the production of the polycarbonate diol of this embodiment, specific examples of dialkyl carbonates are not particularly limited, but include, for example, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, diisobutyl carbonate, ethyl-n-butyl carbonate, and ethyl isobutyl carbonate.

[0032] Examples of diaryl carbonates are not limited to diphenyl carbonate, dityl carbonate, bis(chlorophenyl) carbonate, di-m-cresyl carbonate, etc.

[0033] Examples of alkylene carbonates are not particularly limited, but include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, 1,2-propylene carbonate, 1,2-butylene carbonate, 1,3-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 1,3-pentylene carbonate, 1,4-pentylene carbonate, 1,5-pentylene carbonate, 2,3-pentylene carbonate, 2,4-pentylene carbonate, neopentyl carbonate, and the like.

[0034] These may be used individually or in combination of two or more types.

[0035] Among these carbonate esters, dimethyl carbonate, diethyl carbonate, ethylene carbonate, and diphenyl carbonate are particularly preferred because they are inexpensive and readily available as industrial raw materials, have good reactivity, and produce a small amount of by-product alcohol.

[0036] <1-1-3. Usage ratio of raw material monomers> In the method for producing polycarbonate diols of this embodiment, the amount of carbonate ester used needs to be appropriately changed depending on the target molecular weight of the polycarbonate diol and is not particularly limited, but the lower limit is preferably 0.5, more preferably 0.7, and even more preferably 0.8 in molar ratio to 1 mole of total dihydroxy compounds, and the upper limit is usually 1.5, preferably 1.3, and more preferably 1.2. If the amount of carbonate ester used is below the above upper limit, the proportion of polycarbonate diols whose terminal groups are not hydroxyl groups can be suppressed, or the polycarbonate diol of this embodiment with a molecular weight within a predetermined range can be produced, and if it is above the lower limit, polymerization tends to proceed up to the predetermined molecular weight.

[0037] <1-2. Transesterification catalysts> The method for producing polycarbonate diol in this embodiment involves the presence of at least two transesterification catalysts: transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table, and transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals from group 2 of the long-period periodic table.

[0038] <1-2-1. Transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table> One form of the transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table is preferably at least one metal complex and / or hydrate thereof (which may be a form in which multiple such metal complexes and / or hydrates are associated), represented by the following formula (1). [ka] (In the formula, R1 and R3 each independently represent a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon groups of R1 and R3 may be substituted with halogen atoms or may have oxygen atoms; R2 represents hydrogen, a halogen atom, or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R2 may be substituted with halogen atoms or may have oxygen atoms; M1 represents at least one metal selected from the group consisting of metals in groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table, and n is 1, 2, or 3.)

[0039] The ligand for the metal complex represented by formula (1) is an acetylacetone analog, and can be described in a form where the anion is delocalized, as shown in formula (7) below. Similarly, it can also be expressed as an equilibrium state of three organic anions, as shown in formula (8) below. [ka] [ka] (In equations (7) and (8), R1, R2, and R3 are defined as in equation (1) above.)

[0040] Methods for preparing the transesterification catalyst represented by formula (1) include, for example, the method shown in formula (9) below, which involves reacting a metal halide salt with an acetylacetone analog in the presence of a base, or the method shown in formula (10) below, which involves exchanging a metal alkoxide with an acetylacetone analog. However, the method is not limited to these. [ka] [ka] (In formulas (9) and (10) above, R1, R2, R3, M1 and n are defined as in formula (1) above, X is any halogen atom, R 11 (This is any hydrocarbon group.)

[0041] Furthermore, in addition to the transesterification catalysts represented by formula (1), it is also possible to use auxiliary basic compounds such as transition metal compounds, basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds.

[0042] In formula (1), R1 and R3 are not particularly limited, but examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, phenyl group, benzyl group, monofluoromethyl group, difluoromethyl group, trifluoromethyl group, monochloromethyl group, dichloromethyl group, trichloromethyl group, etc. Of these, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, phenyl group, benzyl group, trifluoromethyl group, and trichloromethyl group are particularly preferred. Note that R1 and R3 may be the same or different.

[0043] Furthermore, while R2 is not particularly limited, examples include hydrogen, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, phenyl group, benzyl group, monofluoromethyl group, difluoromethyl group, trifluoromethyl group, monochloromethyl group, dichloromethyl group, trichloromethyl group, fluorine atom, chlorine atom, bromine atom, iodine atom, etc. Of these, hydrogen, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, and tert-butyl group are preferred, and hydrogen is particularly preferred.

[0044] The metal (M1) selected from the group consisting of groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table is not particularly limited, but from the viewpoint of catalytic activity, molybdenum, manganese, iron, cobalt, nickel, and copper are preferred, and among these, manganese is particularly preferred.

[0045] Furthermore, in this embodiment, the organometallic complexes with these acetylacetone analogs used as transesterification catalysts can also be used as hydrates.

[0046] Another form of the transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table is preferably a salt and / or hydrate thereof of at least one carboxylic acid and at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table, represented by the following formula (2). [ka] (In the formula, R4 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R4 may be substituted with a halogen atom or may have an oxygen atom.)

[0047] Examples of carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, palmitic acid, margaric acid, and stearic acid. Of these, acetic acid, propionic acid, and butyric acid are preferred, with acetic acid being particularly preferred.

[0048] The metal (M1) selected from the group consisting of groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table is not particularly limited, but from the viewpoint of catalytic activity, molybdenum, manganese, iron, cobalt, nickel, and copper are preferred, and among these, manganese is particularly preferred.

[0049] Furthermore, in this embodiment, the salts of these carboxylic acids used as transesterification catalysts can also be used as hydrates.

[0050] <1-2-2. Transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Group 2 of the long-period periodic table> The method for producing polycarbonate diol in this embodiment involves using the transesterification catalyst A1 described above in combination with transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Group 2 of the long-period periodic table.

[0051] The metals of Group 2 of the long-period periodic table are not particularly limited, but examples include beryllium, magnesium, calcium, strontium, barium, and radium. Among these, magnesium and calcium are preferred because they have high catalytic activity. Calcium is particularly preferred because it has high activity and produces a small amount of ether bonding in the resulting polycarbonate diol.

[0052] The form of the transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Group 2 of the long-period periodic table is not particularly limited, but examples include salts with inorganic acids, salts with organic acids, alkoxides of various alcohols, and hydroxides.

[0053] One form of the transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of the second metal of the long-period periodic table is preferably at least one metal complex and / or hydrate thereof (which may be a form in which multiple such metal complexes and / or hydrates are associated), represented by the following formula (3). [ka] (In the formula, R5 and R7 each independently represent a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon groups of R5 and R7 may be substituted with halogen atoms or may have oxygen atoms; R6 represents hydrogen, a halogen atom, or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R6 may be substituted with halogen atoms or may have oxygen atoms; M2 represents at least one metal selected from the group consisting of metals in Group 2 of the long-period periodic table, and n is 1, 2, or 3.)

[0054] In formula (3), R5 and R7 are not particularly limited, but examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, phenyl group, benzyl group, monofluoromethyl group, difluoromethyl group, trifluoromethyl group, monochloromethyl group, dichloromethyl group, trichloromethyl group, etc. Of these, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, phenyl group, benzyl group, trifluoromethyl group, and trichloromethyl group are particularly preferred. Note that R5 and R7 may be the same or different.

[0055] Furthermore, while R6 is not particularly limited, examples include hydrogen, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, phenyl group, benzyl group, monofluoromethyl group, difluoromethyl group, trifluoromethyl group, monochloromethyl group, dichloromethyl group, trichloromethyl group, fluorine atom, chlorine atom, bromine atom, iodine atom, etc. Of these, hydrogen, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, and tert-butyl group are preferred, and hydrogen is particularly preferred.

[0056] The metal (M2) selected from the group consisting of Group 2 of the long-period periodic table is not particularly limited, but from the viewpoint of catalytic activity, magnesium and calcium are preferred, and among these, calcium is particularly preferred.

[0057] Another form of the transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Group 2 of the long-period periodic table is preferably a salt and / or hydrate thereof of at least one carboxylic acid and at least one metal (M1) selected from the group consisting of metals in Group 2 of the long-period periodic table, represented by the following formula (4). [ka] (In the formula, R8 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R8 may be substituted with a halogen atom or may have an oxygen atom.)

[0058] Examples of carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, palmitic acid, margaric acid, and stearic acid. Of these, acetic acid, propionic acid, and butyric acid are preferred, with acetic acid being particularly preferred.

[0059] The metal (M2) selected from the group consisting of Group 2 of the long-period periodic table is not particularly limited, but from the viewpoint of catalytic activity, magnesium and calcium are preferred, and among these, calcium is particularly preferred.

[0060] Another form of the transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Group 2 of the long-period periodic table is preferred because it exhibits high catalytic activity and low discoloration, as is the alkoxide of at least one alcohol and at least one metal (M2) selected from the group consisting of metals in Group 2 of the long-period periodic table, as represented by the following formula (5). [ka] (In the formula, R9 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R9 may be substituted with a halogen atom or may have an oxygen atom.)

[0061] The alkoxide represented by formula (5), consisting of at least one alcohol and a metal of Group 2 of the long-period periodic table, is not particularly limited, but examples include beryllium alkoxide, magnesium alkoxide, calcium alkoxide, strontium alkoxide, barium alkoxide, and radium alkoxide. Among these alkoxides, magnesium alkoxide and calcium alkoxide are preferred, and calcium alkoxide is particularly preferred, as they have high catalytic activity and produce a small amount of ether bonding and low coloration in the resulting polycarbonate diol.

[0062] Specific examples of alkoxides with metals of Group 2 of the long-period periodic table include dimethoxymagnesium, diethoxymagnesium, dipropoxymagnesium, dibutoxymagnesium, dimethoxycalcium, diethoxycalcium, dipropoxycalcium, and dibutoxycalcium, among which dimethoxycalcium, diethoxycalcium, dipropoxycalcium, and dibutoxycalcium are particularly preferred.

[0063] The method for producing polycarbonate diol in this embodiment involves the presence of at least two transesterification catalysts: transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table, and transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals from group 2 of the long-period periodic table.

[0064] By using transesterification catalyst A1 and transesterification catalyst A2 in combination, rather than using either A1 or A2 alone, higher catalytic activity can be obtained, allowing for the efficient production of polycarbonate diols.

[0065] Although the mechanism by which such effects are produced is not clear, the inventors of the present invention presume that it is due to the reaction mechanism shown in formula (11) below. First, transesterification catalyst A1, which contains at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table, coordinates to the carbonyl oxygen of the carbonate group as a Lewis acid. As a result, the cationicity of the carbonyl carbon is increased, activating the transesterification reaction. On the other hand, transesterification catalyst A2, which contains at least one metal M1 selected from the group consisting of metals from group 2 of the long-period periodic table, is thought to anionize the oxygen of the alcohol (alcohol species involved in transesterification; here meaning the terminal alcohol of a monomer diol or polycarbonate diol), thereby promoting the reaction with the activated carbonyl carbon. [ka] (In the formula, M1 represents at least one metal selected from the group consisting of metals from groups 6, 7, 8, 9, 10 and 11 of the long-period periodic table, M2 represents at least one metal selected from the group consisting of the second metal of the long-period periodic table, R 12 , R 13 , R 14 represents any hydrocarbon, and L1 and L2 represent any ligands (there may be multiple ligands).

[0066] The amounts of the transesterification catalyst used in this embodiment are as follows: the amount of transesterification catalyst A1, as a total amount of the metal (M1), is preferably 0.5 ppm to 20 ppm, more preferably 1 ppm to 10 ppm, and even more preferably 2 ppm to 7 ppm, relative to the total amount of the dihydroxy compound and carbonate ester; and the amount of transesterification catalyst A2, as a total amount of the metal (M2), is preferably 0.25 ppm to 10 ppm, more preferably 0.5 ppm to 5 ppm, and even more preferably 1 ppm to 3 ppm, relative to the total amount of the dihydroxy compound and carbonate ester.

[0067] When the amount of transesterification catalyst A1 is 0.5 ppm or more in total as metal (M1), the transesterification reaction rate tends to be faster. Furthermore, when the amount of transesterification catalyst is 20 ppm or less in total as metal (M1), the discoloration of the resulting polycarbonate diol can be suppressed, and when used as a urethane raw material, the urethane formation reaction tends to be more stable, resulting in a better color tone for the resulting urethane and improved heat resistance.

[0068] When the amount of transesterification catalyst A2 is 0.25 ppm or more in total as metal (M2), the transesterification reaction rate tends to be faster. Furthermore, when the amount of transesterification catalyst is 10 ppm or less in total as metal (M2), the coloration of the resulting polycarbonate diol can be suppressed, the number of ether bonds is reduced, and when used as a urethane raw material, the urethane formation reaction tends to be more stable, resulting in a better color tone for the resulting urethane and improved heat resistance.

[0069] <1-3. Method for producing polycarbonate diol> In this embodiment, a polycarbonate diol is produced by transesterifying one or more of the aforementioned dihydroxy compounds with one or more of the aforementioned carbonate esters in the presence of at least two of the aforementioned transesterification catalysts A1 and A2.

[0070] <1-3-1. Reaction conditions, etc.> There are no particular restrictions on the method of preparing the reaction materials. For example, one could prepare the entire amounts of one or more dihydroxy compounds, carbonate esters, and catalysts simultaneously and use them in the reaction. Alternatively, if the carbonate ester is a solid, one could prepare it first, heat and melt it, and then add the dihydroxy compound catalyst. Conversely, if the dihydroxy compound is a solid, one could prepare it first, melt it, and then add the carbonate ester and catalyst. The method can be freely chosen.

[0071] The reaction temperature during the transesterification reaction can be any temperature at which a practical reaction rate can be obtained. The temperature is not particularly limited, but the lower limit is preferably 80°C, more preferably 110°C, and even more preferably 130°C. The upper limit of the reaction temperature is preferably 220°C, more preferably 200°C, even more preferably 180°C, and particularly preferably 170°C. When the reaction temperature is above the lower limit, the transesterification reaction tends to proceed at a practical rate. When the reaction temperature is below the upper limit, the discoloration of the resulting polycarbonate diol can be suppressed, the formation of ether bonds can be suppressed, and the quality tends to improve, such as having good turbidity.

[0072] In particular, the method for producing polycarbonate diols in this embodiment, by using at least two transesterification catalysts A1 and A2 containing specific metals, allows for the efficient production of polycarbonate diols in a short time even under mild reaction conditions, for example, at low temperatures of 170°C or below (preferably 160°C or below).

[0073] The reaction can be carried out at atmospheric pressure, but since transesterification is an equilibrium reaction, the reaction can be biased toward the product system by distilling off the resulting monohydroxy or dihydroxy compound. Therefore, it is generally preferable to use reduced pressure conditions in the latter half of the reaction to distill off the monohydroxy or dihydroxy compound. Alternatively, it is possible to gradually reduce the pressure from the middle of the reaction to distill off the resulting monohydroxy or dihydroxy compound. Gradually reducing the pressure from the middle of the reaction can suppress the volatilization of unreacted low-boiling point monomers, improve the yield, and tend to yield a polycarbonate diol with a predetermined molecular weight, or, in the case of copolymerization, a polycarbonate diol with a predetermined copolymer composition ratio.

[0074] The reaction pressure is appropriately selected depending on the type of alcohol derived from the carbonate ester to be distilled. For example, when the alcohol to be distilled is a relatively low-boiling point alcohol such as methanol, the preferred reactor pressure is 5 kPa to atmospheric pressure, more preferably 7 kPa to 15 kPa. When the alcohol to be distilled is a relatively high-boiling point alcohol such as ethylene glycol, the preferred reactor pressure is 1 to 10 kPa, more preferably 3 kPa to 7 kPa.

[0075] Furthermore, in order to prevent the distillation of the starting materials in the initial stages of these reactions, it is possible to equip the reactor with a rectification column having 10 or more theoretical stages, preferably 15 or more, and more preferably 20 or more stages, so that the monohydroxy or dihydroxy compounds produced by the reaction from the carbonate ester can be efficiently separated and distilled off while refluxing and separating the azeotropic starting materials, carbonate ester and dihydroxy compounds. In this case, the charged starting material monomers are not lost and the ratio of reagents can be accurately adjusted, which is preferable.

[0076] Furthermore, it is preferable to switch to simple distillation at the end of the reaction and increase the degree of reduced pressure, as this allows for the efficient removal of by-products such as alcohols and diols, monohydroxy or dihydroxy compounds such as phenols, residual monomers such as carbonate esters, and cyclic carbonates (cyclic oligomers) that may cause turbidity.

[0077] The reaction pressure at the end of the reaction is not particularly limited, but is usually preferably 5 kPa, more preferably 2 kPa, and even more preferably 1 kPa. In order to effectively distill off these low-boiling components, the reaction can also be carried out while passing a small amount of inert gas such as nitrogen, argon, or helium through the reaction system.

[0078] When using carbonate esters or dihydroxy compounds with low boiling points in transesterification reactions, it is possible to carry out the reaction at or near the boiling point of the carbonate ester or dihydroxy compound in the initial stages, and then gradually increase the temperature as the reaction progresses to further advance the reaction. This method is preferable because it prevents the removal of unreacted carbonate esters or dihydroxy compounds during the initial stages of the reaction.

[0079] <1-3-2. Polymerization reactor> Polymerization reactions (polycondensation reactions) can be carried out in batch or continuous manner, but continuous methods are superior in terms of the stability of product quality, such as molecular weight. The apparatus used can be of any type, such as a tank, tube, or column, and known polymerization tanks equipped with various types of stirring blades can be used. There are no particular restrictions on the atmosphere during the heating of the apparatus, but from the viewpoint of product quality, it is preferable to carry it out in an inert gas such as nitrogen gas at atmospheric pressure or reduced pressure.

[0080] <1-3-3. Reaction Time> In the method for producing polycarbonate diol according to this embodiment, the time required for the transesterification reaction (polymerization reaction or polycondensation reaction) varies greatly depending on the type and amount of dihydroxy compound, carbonate ester, and transesterification catalyst used, and therefore cannot be specified in general terms. However, the reaction time required to reach a predetermined molecular weight is preferably 20 hours or less, more preferably 10 hours or less, and even more preferably 5 hours or less.

[0081] <1-3-4. Catalyst deactivation> As mentioned above, when a transesterification catalyst is used in the transesterification reaction, the resulting polycarbonate diol usually contains residual transesterification catalyst or its residue, which can make it difficult to control the reaction during the polyurethaneization reaction. To suppress the influence of this residual catalyst, a catalyst deactivator, such as an acidic compound or a phosphorus-based or sulfur-based compound that decomposes into an acidic compound, may be added in an amount approximately equimolar to the transesterification catalyst used. Furthermore, if the catalyst is heat-treated after addition, as described later, the transesterification catalyst can be efficiently deactivated. In addition, by deactivating the catalyst, the color development derived from the transesterification catalyst can be reduced, and a polycarbonate diol can be obtained in which the Hazen color number, measured in accordance with JIS-K0071-1 (1998), is preferably 50 or less, more preferably 30 or less.

[0082] Furthermore, by adding a catalyst deactivator, discoloration and changes in physical properties that occur when the polycarbonate diol composition is stored or handled at high temperatures for extended periods are suppressed due to changes in the terminal structure and skeleton of the polycarbonate diol and residual catalyst.

[0083] The compounds used to deactivate transesterification catalysts (hereinafter sometimes referred to as catalyst deactivators) are not particularly limited, but examples include inorganic phosphoric acids such as phosphoric acid and phosphorous acid, organic phosphoric acid esters such as monobutyl phosphate, dibutyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, and triphenyl phosphite, sulfonic acids, and sulfonic acid esters. These may be used individually or in combination of two or more.

[0084] The amount of catalyst deactivator used is not particularly limited, but as mentioned above, it should be approximately equimolar to the transesterification catalyst used. Specifically, the upper limit is preferably 5 moles, more preferably 2 moles, and the lower limit is preferably 0.8 moles, more preferably 1.0 mole, per mole of transesterification catalyst used. When an amount greater than the lower limit of catalyst deactivator is used, the transesterification catalyst in the reaction product is sufficiently deactivated, and when the resulting polycarbonate diol is used as a raw material for polyurethane production, for example, the reactivity of the polycarbonate diol to the isocyanate group tends to be sufficiently reduced. Furthermore, when an amount less than the upper limit of catalyst deactivator is used, discoloration of the resulting polycarbonate diol can be suppressed, and when used as a urethane raw material, the polymerization of urethane tends to proceed smoothly.

[0085] The deactivation of a transesterification catalyst by adding a catalyst deactivator can be carried out at room temperature, but it is more efficient with heating. The temperature of this heating treatment is not particularly limited, but the upper limit is preferably 140°C, more preferably 130°C, and even more preferably 120°C, and the lower limit is preferably 80°C, more preferably 100°C, and even more preferably 110°C. At temperatures above the lower limit, the deactivation of the transesterification catalyst is efficient with a shorter time, and the degree of deactivation is also sufficient. On the other hand, at temperatures below 140°C, when a phosphorus-based compound is used as the deactivator, the decomposition of the phosphorus-based compound can be suppressed, and deactivation tends to be carried out stably. Therefore, the discoloration of the resulting polycarbonate diol can be suppressed, and when used as a urethane raw material, the urethane formation reaction tends to be more stable.

[0086] There is no specific time limit for the reaction with the catalyst deactivator, but it is typically 1 to 5 hours.

[0087] <1-4. Physical Properties of Polycarbonate Diols> The preferred physical properties of the polycarbonate diol in this embodiment are described below.

[0088] <1-4-1.Molecular weight / molecular weight distribution> The lower limit of the number-average molecular weight (Mn) of the polycarbonate diol in this embodiment is 250, preferably 500, more preferably 750, and even more preferably 1000. On the other hand, the upper limit of the number-average molecular weight (Mn) of the polycarbonate diol in this embodiment is 100,000, preferably 50,000, even more preferably 10,000, and particularly preferably 3,000. When the number-average molecular weight of the polycarbonate diol is above the lower limit, the flexibility and other properties tend to be good when it is made into polyurethane. On the other hand, when the number-average molecular weight of the polycarbonate diol is below the upper limit, the viscosity of the polycarbonate diol tends to decrease, making it easier to handle when it is made into polyurethane.

[0089] Here, the number-average molecular weight of the polycarbonate diol is determined by the hydroxyl value (average hydroxyl value number) of the polycarbonate diol, as shown in the examples below.

[0090] There are no particular limitations on the method for controlling the number-average molecular weight (Mn) of the polycarbonate diol within the aforementioned range. For example, one method is to control the number-average molecular weight (Mn) of the polycarbonate diol within the aforementioned range by adjusting the polycondensation reaction time of the polycarbonate diol and adjusting the amount of dihydroxy compound, which is the raw material monomer, extracted.

[0091] <1-4-2. APHA value> The color of the polycarbonate diol in this embodiment is preferably 50 or less, more preferably 40 or less, even more preferably 30 or less, and particularly preferably 20 or less, when expressed using the Hazen color number (in accordance with JIS K0071-1:1998). The lower limit of the APHA value is not particularly limited, but for example, it is 0 or more. When the APHA value is 50 or less, the color tone of the polyurethane obtained from the polycarbonate diol as a raw material tends to be good, improving its commercial value and thermal stability.

[0092] The method for controlling the APHA value of the polycarbonate diol to the above range is not particularly limited, but examples include carrying out the reaction temperature during the transesterification reaction within the above preferred temperature range, or carrying out the time required for the transesterification reaction (polymerization reaction or polycondensation reaction) within the above preferred range.

[0093] In this embodiment, the APHA value of the polycarbonate diol can be measured by the method described in the examples below.

[0094] <1-4-3. Metals contained in polycarbonate diols> The polycarbonate diol of this embodiment preferably contains at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table, and at least one metal (M2) selected from the group consisting of metals from group 2 of the long-period periodic table.

[0095] In the polycarbonate diol of this embodiment, it is preferable to contain at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table in a total amount of 1 ppm to 25 ppm, more preferably 2 ppm to 15 ppm, and even more preferably 5 ppm to 10 ppm.

[0096] In this embodiment, when the total amount of metal (M1) in the polycarbonate diol is 1 ppm or more, the APHA value is lower, and when used as a raw material for urethane, the reaction rate of urethane formation tends to improve. Furthermore, when the total amount of metal (M1) in the polycarbonate diol of this embodiment is 25 ppm or less, discoloration of the polycarbonate diol due to heating can be suppressed, and when used as a raw material for urethane, the urethane formation reaction tends to be more stable.

[0097] In this embodiment, the polycarbonate diol preferably contains at least one metal (M1) selected from molybdenum, manganese, iron, cobalt, nickel, and copper. Among these, manganese is particularly preferred.

[0098] The metals contained in these polycarbonate diols may be present as residues of the polymerization catalyst, but they may also be intentionally added in predetermined amounts after manufacturing.

[0099] In the polycarbonate diol of this embodiment, it is preferable to contain at least one metal (M2) selected from the group consisting of metals in Group 2 of the long-period periodic table in a total amount of 0.5 ppm to 12.5 ppm, more preferably 0.7 ppm to 7.5 ppm, and even more preferably 1 ppm to 3 ppm.

[0100] In this embodiment, when the total amount of metal (M2) in the polycarbonate diol is 0.5 ppm or more, the APHA value decreases, and when used as a raw material for urethane, the reaction rate of urethane formation tends to improve. Furthermore, when the total amount of metal (M2) in the polycarbonate diol of this embodiment is 12.5 ppm or less, the amount of ether bonding decreases, and discoloration of the polycarbonate diol due to heating can be suppressed, and when used as a raw material for urethane, the urethane formation reaction tends to be more stable.

[0101] In this embodiment, the polycarbonate diol preferably contains at least one metal (M2) selected from the group consisting of beryllium, magnesium, calcium, strontium, barium, and radium. Among these, it is more preferable that at least one metal selected from the group consisting of magnesium and calcium be present, and calcium is particularly preferred.

[0102] The metals contained in these polycarbonate diols may be present as residues of the polymerization catalyst, but they may also be intentionally added in predetermined amounts after manufacturing.

[0103] <1-4-4. Ether bond> The polycarbonate diol of this embodiment is based on a structure in which dihydroxy compounds are polymerized by carbonate groups. However, depending on the manufacturing method, some ether bonds may be mixed in due to side reactions such as the dehydration reaction of some dihydroxy compounds or the decarboxylation reaction of carbonate esters. If the amount of these ether bonds increases, the weather resistance and heat resistance may decrease, so it is preferable to manufacture the polycarbonate diol in a way that does not result in an excessively high proportion of ether bonds. In order to reduce the amount of ether bonds in the polycarbonate diol and ensure properties such as weather resistance and heat resistance, the amount of ether bonds contained in the molecular chain of the polycarbonate diol of this embodiment is usually 5 mol% or less, preferably 3 mol% or less, and more preferably 2 mol% or less, in mol% ratio. The lower limit of the amount of ether bonds is not particularly limited, but for example, it is 0 mol%. These values ​​can be determined by alkaline hydrolysis and measurement by gas chromatography. Specifically, they can be measured by the method described in the examples below.

[0104] The method for controlling the amount of ether bonded polycarbonate diol within the aforementioned range is not particularly limited, but examples include using the transesterification catalyst of the present invention and producing the product under milder reaction conditions and in a shorter time.

[0105] <1-4-5. Ratio of terminal primary hydroxyl groups (OH)> The purity of the terminal primary hydroxyl groups (OH) of the polycarbonate diol in this embodiment is preferably 97% or higher, more preferably 98% or higher, and even more preferably 99% or higher. The upper limit of the terminal primary hydroxyl group (OH) purity is not particularly limited, but for example, it is 100%. When the terminal primary hydroxyl group (OH) purity is 97% or higher, the reaction rate when producing (synthesizing) polyurethane (especially thermoplastic polyurethane) using the polycarbonate diol of this embodiment as a raw material compound tends to be higher, and the strength of the resulting polyurethane tends to be higher.

[0106] In this embodiment, by using the transesterification catalysts A1 and A2 described above, the reaction time can be shortened and polycarbonate diols can be produced under mild reaction conditions, thereby achieving high purity of terminal primary hydroxyl groups (OH).

[0107] In this embodiment, the purity of the terminal primary hydroxyl group (OH) of the polycarbonate diol can be measured by the method described in the examples below.

[0108] <1-5. Uses of Polycarbonate Diol> The polycarbonate diol of this embodiment has excellent mechanical properties and durability, making it suitable for a wide range of applications. For example, it can be widely used in foams, elastomers, paints, fibers, adhesives, flooring materials, sealants, medical materials, artificial leather, coatings, water-based polyurethane paints, and the like. In particular, when the polycarbonate diol of this embodiment is used as a raw material in applications such as artificial leather, synthetic leather, water-based polyurethane, adhesives, medical materials, flooring materials, and coatings, it provides excellent weather resistance, heat resistance, moisture resistance, and abrasion resistance, resulting in less discoloration, resistance to scratches, and less deterioration due to friction, thus providing excellent surface characteristics. For these reasons, it is suitable for use as a raw material in various coatings.

[0109] The polyurethane of this embodiment contains structural units derived from the polycarbonate diol described above. By containing structural units derived from the polycarbonate diol described above, the polyurethane of this embodiment exhibits excellent chemical resistance, heat resistance, and hydrolysis resistance. [Examples]

[0110] The embodiment will be described in more detail below using examples, but this embodiment is not limited in any way by these examples. Unless otherwise specified, the number of parts in the examples is in parts by mass.

[0111] Furthermore, in the following examples and comparative examples, the physical properties of the polycarbonate diol and polyurethane film were tested according to the test methods described below.

[0112] <Testing Method> [Evaluation of Transesterification Catalyst Performance] In the production of polycarbonate diols (PCDs) from dihydroxy compounds and carbonate esters, for example, as shown in formula (12) below, the esterification step reduces the monomer raw material carbonate ester (e.g., ethylene carbonate (EC)) and the dihydroxy compound (raw material diol), producing polycarbonate diols (PCDs), and by-products include hydroxy compounds derived from the carbonate ester (monohydroxy compounds when the raw material carbonate ester is a dialkyl carbonate, and dihydroxy compounds when the raw material carbonate ester is an alkylene carbonate, e.g., ethylene glycol (EG)). [ka] (Here, an example using ethylene carbonate (EC) as the carbonate ester is shown. In this case, ethylene glycol (EG) is produced as a by-product of the reaction.) As a method for evaluating catalytic performance, in the reaction for the formation of polycarbonate diols (PCDs) from dihydroxy compounds and carbonate esters, the amount of hydroxy compound (a monohydroxy compound when the starting carbonate ester is a dialkyl carbonate; a dihydroxy compound when the starting carbonate ester is an alkylene carbonate; for example, ethylene glycol (EG)) distilled after 1 hour and 2 hours from the start of the reaction was determined by gas chromatography, and the carbonate conversion rate was determined by the following formulas (13), (14), or (15). (Method for calculating the carbonate conversion rate when using alkylene carbonates) Carbonate conversion rate (%) = (moles of dihydroxy compound distilled) / (moles of carbonate ester added) × 100 (13) (Method for calculating the carbonate conversion rate when using dialkyl carbonates) Carbonate conversion rate (%) = (Moles of hydroxy compound distilled / 2) / (Moles of carbonate ester added) × 100 (14) (Method for calculating the carbonate conversion rate when using diphenyl carbonate) Carbonate conversion rate (%) = (Number of moles of phenol distilled / 2) / (Number of moles of carbonate ester used in the charge) × 100 (15) The conditions for gas chromatography analysis were as follows: A gas chromatography system GC-14B (Shimadzu Corporation) with DB-WAX (J&W) attached to the column was used, with 1,3-propanediol as the internal standard and an FID detector. The column heating profile involved holding at 100°C for 5 minutes, followed by heating at a rate of 5°C / min to 200°C.

[0113] [Measurement of hydroxyl (OH) value] An acetylation reagent was prepared by making up 12.5 g of acetic anhydride with 50 mL of pyridine. 2.5 to 5.0 g of the sample was accurately weighed into a 100 mL round-bottom flask. 5 mL of the acetylation reagent and 10 mL of toluene were added to the flask using a volumetric pipette, and then a condenser was attached. The solution in the flask was heated and stirred at 100°C for 1 hour. 2.5 mL of distilled water was added to the flask using a volumetric pipette, and the solution in the flask was heated and stirred for a further 10 minutes. After cooling the solution in the flask for 2 to 3 minutes, 12.5 mL of ethanol was added. 2 to 3 drops of phenolphthalein were added to the flask as an indicator, and then the solution in the flask was titrated with 0.5 mol / L potassium hydroxide ethanolate. As a blank test, 5 mL of acetylation reagent, 10 mL of toluene, and 2.5 mL of distilled water were placed in a 100 mL round-bottom flask, heated and stirred for 10 minutes, and then titrated in the same manner as described above. Based on these results, the OH value was calculated using the following formula (16). OH value (mg-KOH / g) = {(ba) × 28.05 × f} / e (16) a: Sample titration volume (mL) b: Titration volume of blank test (mL) e: Sample mass (g) f: Factor of the titrator

[0114] [Number average molecular weight (Mn)] The number-average molecular weight was calculated using the following formula (17). Number-average molecular weight = 2 / (OH value × 10) -3 / 56.11) (17)

[0115] [Measurement of APHA value] In accordance with JIS K0071-1, the Hazen color number (APHA value) was measured by comparing it with a standard solution placed in a colorimetric tube. For polycarbonate diols that are solid at room temperature, the Hazen color number (APHA value) was measured after heating to 70°C and dissolving them.

[0116] [Method for analyzing the amount of ether bonds in polycarbonate diols] 1 g of polycarbonate diol was placed in a 100 mL round-bottom flask, and 30 g of methanol and 8 g of 28% sodium methoxide methanol solution were added. The reaction was carried out at 100°C for 1 hour. After the reaction mixture was cooled to room temperature, 2-3 drops of phenolphthalein were added as an indicator, and the mixture was neutralized with hydrochloric acid. The neutralized reaction mixture was cooled in a refrigerator for 1 hour and then filtered. The resulting filtrate was then analyzed using gas chromatography (GC). For the GC analysis, a gas chromatography GC-14B (Shimadzu Corporation, Japan) equipped with a DB-WAX column (J&W, USA) was used, with 1,3-propanediol as the internal standard and a flame ionization detector (FID) as the detector to quantitatively analyze each component. The column heating profile was set to hold at 110°C for 5 minutes, followed by heating to 200°C at a rate of 5°C / min. Ether bonds are thought to be formed by the dehydration reaction of hydroxyl groups or the decomposition (decarboxylation) of carbonate esters. For example, when polycarbonate diols are produced using ethylene carbonate and hexanediol as raw materials, diethylene glycol and 6-(2-hydroxyethoxy)hexane-1-ol are detected as compounds containing ether bonds.

[0117] [Analytical method for determining the ratio of terminal primary hydroxyl groups (OH) in polycarbonate diols] 70g to 100g of polycarbonate diol was weighed into a 300ml round-bottom flask and heated in a heating bath at approximately 180°C under a pressure of 0.1kPa or less using a rotary evaporator connected to a trap bulb for fraction recovery. The mixture was stirred to obtain a fraction equivalent to approximately 1-2% by mass of the polycarbonate diol, i.e., approximately 1g (0.7-2g), in the trap bulb. This fraction was recovered using approximately 100g (95-105g) of ethanol as a solvent. The recovered solution was subjected to gas chromatography analysis (hereinafter referred to as GC analysis), and the ratio (%) of terminal primary hydroxyl groups (OH) of the polycarbonate diol was calculated from the peak area values ​​of the resulting chromatograph using the following formula (18). For GC analysis, a gas chromatography system 6890 (Hewlett-Packard, USA) was used with a 30m DB-WAX column (J&W, USA) and a 0.25μm film thickness, and a flame ionization detector (FID) was used as the detector. The column heating profile involved heating from 60°C to 250°C at a rate of 10°C / min, followed by holding at that temperature for 15 minutes. The identification of each peak in the GC analysis was performed using the following GC-MS instrument. The GC instrument used was a Hewlett-Packard 6890 (USA) with a DB-WAX (J&W, USA) column. In the GC instrument, the temperature was increased from an initial temperature of 40°C to 220°C at a heating rate of 10°C / min. The MS instrument used was an Auto-massSUN (JEOL, Japan). In the MS instrument, the ionization voltage was 70eV, the scan range was m / z = 10 to 500, and the photomultiplier gain was 450V. Terminal primary OH ratio (%)=B÷A×100 (18) A: Sum of peak areas for alcohols containing diols (excluding ethanol) B: Sum of peak areas of diols with primary OH groups at both ends

[0118] [Amount of residual catalyst in polycarbonate diol] Approximately 0.1 g of polycarbonate diol was measured and dissolved in 4 mL of acetonitrile to obtain a solution. Then, 20 mL of pure water was added to the obtained solution to precipitate the polycarbonate diol, and the precipitated polycarbonate diol was removed by filtration. The filtered solution was then diluted with pure water to a predetermined concentration. The metal ion concentration in the diluted solution was analyzed by ion chromatography. The metal ion concentration of acetonitrile used as the solvent was measured as a blank value, and the metal ion concentration of this solvent was subtracted from the metal ion concentration in the diluted solution to obtain the metal ion concentration of the polycarbonate diol product. The measurement conditions were as follows. Using calibration curves for various metals prepared in advance, the concentrations of various metals remaining in the polycarbonate diol were determined. High-performance liquid chromatography (HPCL) measurement conditions Device: Waters2690 Column: IonPac CS12A Flow rate: 1.0ml / min Injection amount: 1.5ml Pressure: 950~980 psi Column temperature: 35℃ Detector sensitivity: RANGE 200μS Suppressor: CSRS 60mA Eluent: 20 mmol / l methanesulfonic acid aqueous solution

[0119] [Measuring the molecular weight of polyurethane] A portion of the polyurethane film was cut out, and an N,N-dimethylacetamide (DMF) solution was prepared to achieve a polyurethane concentration of 0.1% by mass. The molecular weight of each polyurethane component was measured using the prepared DMF solution as follows. A GPC instrument (Tosoh Corporation, product name "HLC-8320" (column: Tskgel SuperHM-H, 4 columns)) was used for the measurement. A solution of 2.6 g of lithium bromide dissolved in 1 L of dimethylacetamide was used as the eluent. From the obtained measurement results, the number-average molecular weight (Mn) of the polyurethane in terms of standard polystyrene was calculated.

[0120] [Tensile test of polyurethane film at room temperature] In accordance with JIS K6301 (2010), test specimens were prepared from polyurethane film in the form of strips measuring 10 mm in width, 100 mm in length, and approximately 0.5 mm in thickness. Tensile tests were performed on the prepared test specimens using a tensile testing machine (Orientec Co., Ltd., product name "Tensilon, model RTE-1210") at a chuck distance of 20 mm, a tensile speed of 100 mm / min, and a temperature of 23°C (relative humidity 55%). In this tensile test, the stress (100% modulus), fracture strength, and fracture elongation were measured when the test specimen was 100% elongated.

[0121] [Evaluation of polyurethane's resistance to oleic acid] A 3cm x 3cm test specimen was cut from a polyurethane film. The mass of the test specimen was measured using a precision balance. Then, the test specimen was placed in a 250mL glass bottle containing 50mL of oleic acid as the test solvent, and the specimen was left to stand in a constant temperature bath under a nitrogen atmosphere at 80°C for 16 hours to perform a chemical resistance test. After the test, the test specimen was removed and lightly wiped on both sides with a paper wiper. The mass of the test specimen was then measured using a precision balance. The rate of mass change (increase rate) from before the test was calculated using the following formula. A mass change rate close to 0% indicates good resistance to oleic acid (chemical resistance). Mass change rate (%) = (Mass of test specimen after testing - Mass of test specimen before testing) / Mass of test specimen before testing × 100

[0122] [Evaluation of the heat resistance of polyurethane] A strip of polyurethane film was prepared from the polyurethane film, measuring 10 mm in width, 100 mm in length, and approximately 50 μm in thickness. The specimen was heated in a gear oven at 120°C for 1000 hours. The breaking strength of the heated specimen was measured in the same manner as in the [room temperature tensile test] described above. The percentage of the breaking strength retained was calculated using the following formula (19). Breaking strength retention rate (%) = Breaking strength of the test specimen after heating / Breaking strength of the test specimen before testing × 100 (19)

[0123] [Evaluation of the hydrolysis resistance of polyurethane] A strip-shaped test specimen measuring 10 mm in width, 100 mm in length, and approximately 50 μm in thickness was prepared from a polyurethane film. The test specimen was heated in a constant temperature and humidity chamber at 85°C and 85% relative humidity for 200 hours. The breaking strength of the heated test specimen was measured in the same manner as in the [room temperature tensile test] described above. The percentage of the breaking strength retained was calculated using the following formula (20). Breaking strength retention rate (%) = Breaking strength of the test specimen after heating / Breaking strength of the test specimen before testing × 100 (20)

[0124] [Compound abbreviations] The abbreviations for the compounds in the following examples and comparative examples are as follows: Mn(acac)2·2H2O: Manganese(II) acetylacetonate dihydrate Mn(acac)3: Manganese(III) Acetylacetonate Mn(OAc)2·4H2O: Manganese(II) acetate tetrahydrate Mn(tBuCOCH2COtBu)2·2H2O:2,2,6,6-Tetramethyl-3,5-Heptanedionatomangane(II) dihydrate Mn(CF3COCH2COCF3)2·2H2O: Hexafluoroacetylacetonatomanganese dihydrate [Mo(acac)]2: Molybdenum(II) acetylacetonate dimer Fe(acac)3: Iron(III) acetylacetonate Co(acac)2·2H2O: Cobalt(II) acetylacetonate dihydrate Ni(acac)2·2H2O: Nickel(II) acetylacetonate dihydrate Cu(acac)2: Copper(II) acetylacetonate Ti(OBu)4: Tetra-n-butyl titanate Ti(acac)2(OiPr)2: Titanium (IV) bis(acetylacetonate) diisopropoxide Li-OMe: Lithium Methoxyde Mg(acac)2·2H2O: Magnesium(II) acetylacetonate dihydrate Mg(OAc)2·4H2O: Magnesium acetate tetrahydrate Ca(acac)2·2H2O: Calcium(II) acetylacetonate dihydrate Ca(OAc)2·H2O: Calcium acetate monohydrate Ca(OMe)2: Calcium dimethoxide Ba(OAc)2: Barium acetate EC: Ethylene carbonate EG: Ethylene glycol DMC: Dimethyl carbonate DEC: Diethyl carbonate DPC: Diphenyl carbonate 13PDO:1,3-Propanediol 14BDO:1,4-butanediol 15PDO:1,5-Pentanediol 16HDO:1,6-Hexanediol 110DDO:1,10-decanediol 3M15PDO:3-methyl-1,5-pentanediol

[0125] [Example 1] In a 1 L separable flask equipped with a stirrer, thermometer, and an Aldershaw vacuum jacket with a reflux head (15 theoretical plates), 355 g (3.00 mol) of 1,6-hexanediol and 264 g (3.00 mol) of ethylene carbonate were charged as starting monomers. 16.3 mg of Mn(acac)2·2H2O and 6.8 mg of Ca(OAc)2·H2O were added as catalysts. The starting materials in the flask were heated in an oil bath set to 180°C, and the starting monomers were polycondensed by transesterification for 2 hours at an internal flask temperature of 150°C and a vacuum of 4 kPa, while removing a portion of the fraction through the reflux head, to obtain a polycarbonate diol. The carbonate conversion rate was analyzed by gas chromatography 1 hour and 2 hours after the start of the reaction. The amount of ether binding was also measured 2 hours after the start of the reaction. The results are shown in Table 1.

[0126] [Examples 2-15, Comparative Examples 1-5] Except for the type and amount of catalyst added as shown in Table 1, the raw material monomers were polycondensed by transesterification in the same manner as in Example 1 to obtain a polycarbonate diol. Similar to Example 1, the carbonate conversion rate was analyzed by gas chromatography 1 hour and 2 hours after the start of the reaction. The amount of ether bonded 2 hours after the start of the reaction was also measured. The results are shown in Table 1.

[0127] [Table 1]

[0128] [Examples 16-26] Except for the type and amount of catalyst added as shown in Table 2, and the reaction temperature as shown in Table 2, the starting monomers were polycondensed by transesterification in the same manner as in Example 1 to obtain a polycarbonate diol. As in Example 1, the carbonate conversion rate was analyzed by gas chromatography 1 hour and 2 hours after the start of the reaction. In addition, the amount of ether binding and APHA were measured 2 hours after the start of the reaction. The results are shown in Table 2.

[0129] [Table 2]

[0130] [Examples 27-30, Comparative Examples 6, 7] Except for the type and amount of catalyst added and the type of carbonate ester used, as in Example 1, the raw material monomers were polycondensed by transesterification to obtain a polycarbonate diol. As in Example 1, the carbonate conversion rate was analyzed by gas chromatography 1 hour and 2 hours after the start of the reaction. The results are shown in Table 3.

[0131] [Table 3]

[0132] [Examples 31-38] Except for the type and amount of catalyst added and the type and amount of dihydroxy compound used, which are listed in Table 4, the starting monomers were polycondensed by transesterification in the same manner as in Example 1 to obtain a polycarbonate diol. As in Example 1, the carbonate conversion rate was analyzed by gas chromatography 1 hour and 2 hours after the start of the reaction. The results are shown in Table 4.

[0133] [Table 4]

[0134] [Example 39] In a 1 L separable flask equipped with a stirrer, thermometer, and an Aldershaw vacuum jacket with a reflux head (15 theoretical stages), 355 g (3.00 mol) of 1,6-hexanediol and 264 g (3.00 mol) of ethylene carbonate were charged. 13.8 mg of Mn(OAc)2·4H2O and 6.8 mg of Ca(OAc)2·H2O were added as catalysts. The starting materials in the flask were heated in an oil bath set to 180°C. Under a flask temperature of 150°C and a vacuum of 4 kPa, the starting monomers were polycondensed by transesterification for 2 hours while removing a portion of the fraction through the reflux head to obtain a polycarbonate diol. The carbonate conversion rate at this point (2 hours after the start of the reaction) was measured. The measurement results are shown in Table 5. Subsequently, the process was switched to simple distillation, and while gradually reducing the pressure to 0.5 kPa, the oil bath temperature was set to 185°C, and the reaction was carried out for 1 hour at an internal flask temperature of 160°C to distill the monomer and obtain a polycarbonate diol. After introducing nitrogen gas to bring the pressure to atmospheric pressure, the oil bath temperature was set to 125°C, and the internal flask temperature was set to 110-120°C. Monobutyl phosphate was added in an equimolar amount to the amount of catalyst used as a catalyst deactivator, and the mixture was stirred at a temperature of 110-120°C for 2 hours. The results of the analysis of the obtained polycarbonate diol are shown in Table 5. This polycarbonate diol is referred to as PC1.

[0135] [Examples 40-42] Except for the type and amount of dihydroxy compound used, as shown in Table 5, the starting monomers were polycondensed by transesterification in the same manner as in Example 39 to obtain polycarbonate diols. The carbonate conversion rate 2 hours after the start of the reaction and the properties of the obtained polymeric polycarbonate diols are shown in Table 5. The obtained polycarbonate diols are referred to as PC2, PC3, and PC4, respectively.

[0136] [Example 43] Except for using the dihydroxy compounds listed in Table 5 in terms of type and quantity, and setting the reaction time after switching to simple distillation to 0.5 hours, the starting monomers were polycondensed by transesterification in the same manner as in Example 42 to obtain a polycarbonate diol. The carbonate conversion rate 2 hours after the start of the reaction and the properties of the obtained polymeric polycarbonate diol are shown in Table 5. The obtained polycarbonate diol is referred to as PC5.

[0137] [Example 44] Except for using the dihydroxy compounds listed in Table 5 in terms of type and quantity, and setting the reaction time after switching to simple distillation to 2 hours, the starting monomers were polycondensed by transesterification in the same manner as in Example 42 to obtain a polycarbonate diol. The carbonate conversion rate after 2 hours from the start of the reaction and the properties of the obtained polymeric polycarbonate diol are shown in Table 5. The obtained polycarbonate diol is referred to as PC6.

[0138] [Comparative Example 8] In a 1 L separable flask equipped with a stirrer, thermometer, and an Aldershaw vacuum jacket with a reflux head (15 theoretical plates), 156 g of 1,5-pentanediol, 177 g of 1,6-hexanediol, and 264 g (3.00 mol) of ethylene carbonate were charged as starting monomers, and 20.7 mg of Mn(OAc)2·4H2O was added as a catalyst. The starting materials in the flask were heated in an oil bath set to 180°C, and the reaction was carried out for 7 hours at an internal flask temperature of 150°C and a vacuum of 4 kPa, while a portion of the fraction was withdrawn through the reflux head. (A portion of the reaction solution was withdrawn 2 hours after the start of the reaction, and the carbonate conversion rate after 2 hours was determined.) Subsequently, the reaction was switched to simple distillation, and while gradually reducing the pressure to 0.5 kPa, the oil bath temperature was set to 185°C, and the reaction was carried out for 4 hours at an internal flask temperature of 160-170°C, and the monomers were distilled to obtain polycarbonate diol. After introducing nitrogen gas to bring the pressure to atmospheric pressure, the oil bath temperature was set to 125°C, and the internal temperature of the flask was set to 110-120°C. Monobutyl phosphate was added as a catalyst deactivator in an equimolar amount to the amount of catalyst charged, and the mixture was stirred at 110-120°C for 3 hours. The results of the analysis of the obtained polycarbonate diol are shown in Table 5. This polycarbonate diol is referred to as PC7.

[0139] [Comparative Example 9] In a 1 L separable flask equipped with a stirrer, thermometer, and an Aldershaw vacuum jacket with a reflux head (15 theoretical plates), 156 g of 1,5-pentanediol, 177 g of 1,6-hexanediol, and 264 g (3.00 mol) of ethylene carbonate were charged as starting monomers, and 20.4 mg of Ca(OAc)2·H2O was added as a catalyst. The starting materials in the flask were heated in an oil bath set to 180°C, and the reaction was carried out for 7 hours at an internal flask temperature of 150°C and a vacuum of 4 kPa, while a portion of the fraction was withdrawn through the reflux head. (A portion of the reaction solution was withdrawn 2 hours after the start of the reaction, and the carbonate addition rate at 2 hours was determined.) Subsequently, the reaction was switched to simple distillation, and while gradually reducing the pressure to 0.5 kPa, the oil bath temperature was set to 185°C, and the reaction was carried out for 4 hours at an internal flask temperature of 160-170°C, and the monomers were distilled to obtain polycarbonate diol. After introducing nitrogen gas and bringing the pressure to atmospheric pressure, the oil bath temperature was set to 125°C, and the internal temperature of the flask was set to 110-120°C. Monobutyl phosphate was added as a catalyst deactivator in an equimolar amount to the amount of catalyst charged, and the mixture was stirred at 110-120°C for 3 hours. The results of the analysis of the obtained polycarbonate diol are shown in Table 5. This polycarbonate diol is referred to as PC8.

[0140] [Table 5]

[0141] [Example 45] A 200 mL separable flask equipped with a stirring blade and nitrogen-sealed, which had been heated in an oil bath at 60°C, was charged with 15.7 g of diphenylmethane-4,4'-diisocyanate (hereinafter also referred to as "MDI"), 180 mL of N,N-dimethylformamide (hereinafter also referred to as "DMF") as the solvent, and 0.003 g of dibutyltin dilaurate as the catalyst. A solution of 42 g of polycarbonate diol PC1 and 60 g of DMF, which had been preheated to 60°C, was added dropwise using a dropping funnel over approximately 1 hour to obtain the solution. The obtained solution was stirred for 1 hour, after which 3.2 g of 1,4-butanediol (hereinafter also referred to as "14BDO") was added. The solution was stirred further at 60°C for 3 hours, and then 1 g of ethyl alcohol was added to stop the reaction. The obtained polyurethane solution was applied to a polypropylene resin sheet (100 mm wide, 1200 mm long, 1 mm thick) using an applicator, in a layer measuring 80 mm wide, 100 mm long, and 0.6 mm thick, to obtain a coating film. The obtained coating film was dried on a hot plate at a surface temperature of 60°C for 2 hours, followed by drying in an oven at 100°C for 12 hours. Furthermore, it was left to stand for more than 48 hours under constant temperature and humidity conditions of 23°C and 55% RH to obtain a polyurethane film. The obtained polyurethane film was subjected to evaluation of various physical properties. The evaluation results are shown in Table 6.

[0142] [Examples 46-50, Comparative Examples 10 and 11] Polyurethane films were obtained in the same manner as in Example 45, except that PC2 to PC8 were used as polycarbonate diols and the amounts of MDI and 14BDO were as shown in Table 6. The obtained polyurethane films were subjected to evaluation of various physical properties. The evaluation results are shown in Table 6.

[0143] [Table 6]

Claims

1. The process includes a step of obtaining a polycarbonate diol by polycondensation of a dihydroxy compound and a carbonate ester as raw material monomers in the presence of a transesterification catalyst via a transesterification reaction. The transesterification catalyst comprises transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table, and transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals from group 2 of the long-period periodic table. Transesterification catalyst A1, At least one metal complex and / or hydrate thereof, represented by the following formula (1): 【Chemistry 1】 (In the formula, R1 and R3 each independently represent a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon groups of R1 and R3 may be substituted with halogen atoms or may have oxygen atoms; R2 represents hydrogen, a halogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R2 may be substituted with halogen atoms or may have oxygen atoms; M1 represents at least one metal selected from the group consisting of metals of groups 6, 7, 8, 9, 10 and 11 of the long-period periodic table, and n is 1, 2 or 3.) and / or Salts and / or hydrates thereof of at least one carboxylic acid represented by the following formula (2) and at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10 and 11 of the long-period periodic table: 【Chemistry 2】 (In the formula, R4 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R4 may be substituted with a halogen atom or may have an oxygen atom.) And, Transesterification catalyst A2, At least one metal complex and / or hydrate thereof, represented by the following formula (3): 【Transformation 3】 (In the formula, R5 and R7 each independently represent a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon groups of R5 and R7 may be substituted with halogen atoms or may have oxygen atoms; R6 represents hydrogen, a halogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R6 may be substituted with halogen atoms or may have oxygen atoms; M2 represents at least one metal selected from the group consisting of metals in Group 2 of the long-period periodic table, and n is 1, 2, or 3.) and / or A salt and / or hydrate thereof of at least one carboxylic acid represented by the following formula (4) and at least one metal (M2) selected from the group consisting of metals in Group 2 of the long-period periodic table: 【Chemistry 4】 (In the formula, R 8 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R 8 may be substituted with a halogen atom or may have an oxygen atom.) and / or The alkoxides of at least one alcohol and at least one metal (M2) selected from the group consisting of metals in Group 2 of the long-period periodic table, as represented by the following formula (5): 【Transformation 5】 (In the formula, R9 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R9 may be substituted with a halogen atom or may have an oxygen atom.) That is, A method for producing polycarbonate diol.

2. A method for producing a polycarbonate diol according to claim 1, wherein the metal (M1) is at least one metal selected from the group consisting of molybdenum, manganese, iron, cobalt, nickel, and copper.

3. A method for producing a polycarbonate diol according to claim 2, wherein the metal (M1) is manganese.

4. A method for producing a polycarbonate diol according to any one of claims 1 to 3, wherein the metal (M2) is at least one metal selected from the group consisting of magnesium and calcium.

5. A method for producing a polycarbonate diol according to claim 4, wherein the metal (M2) is calcium.

6. The amount of transesterification catalyst A1 is such that, as the total amount of the metal (M1), it is 0.5 ppm or more and 20 ppm or less relative to the total amount of the dihydroxy compound and carbonate ester. A method for producing a polycarbonate diol according to any one of claims 1 to 3, wherein the amount of transesterification catalyst A2 is 0.25 ppm or more and 10 ppm or less as the total amount of the metal (M2) relative to the total amount of the dihydroxy compound and the carbonate ester.

7. A method for producing a polycarbonate diol according to any one of claims 1 to 3, wherein the dihydroxy compound comprises at least one selected from the group consisting of aliphatic dihydroxy compounds having a structure represented by the following formula (6). 【Transformation 6】 (In the formula, R 10 (This represents a divalent aliphatic hydrocarbon with 2 to 20 carbon atoms.)

8. A method for producing a polycarbonate diol according to any one of claims 1 to 3, wherein the carbonate ester is at least one selected from the group consisting of alkylene carbonate, dialkyl carbonate, and diaryl carbonate.

9. It is a polycondensate resulting from a transesterification reaction between a dihydroxy compound and a carbonate ester. The number-average molecular weight is between 250 and 100,000. The polycarbonate diol contains at least one metal (M1) selected from the group consisting of metals from groups 6, 7, 8, 9, 10, and 11 of the long-period periodic table, in a total amount of 1 ppm to 25 ppm, and at least one metal (M2) selected from the group consisting of metals from group 2 of the long-period periodic table, in a total amount of 0.5 ppm to 12.5 ppm. The Hazen color number measured in accordance with JIS-K0071-1 (1998) is 20 or less. The amount of ether bonded material is 5 mol% or less. A polycarbonate diol with a terminal primary hydroxyl group (OH) purity of 98% or higher.

10. The polycarbonate diol according to claim 9, wherein metal (M1) is at least one metal selected from the group consisting of molybdenum, manganese, iron, cobalt, nickel, and copper, and metal (M2) is at least one metal selected from the group consisting of magnesium and calcium.

11. The polycarbonate diol according to claim 9 or 10, wherein metal (M1) is manganese and metal (M2) is calcium.

12. A polyurethane comprising a structural unit derived from a polycarbonate diol as described in claim 9 or 10.

Images