Method for producing polycarbonate diol, polycarbonate diol and transesterification catalyst

Abstract

This method for producing a polycarbonate diol includes a step for obtaining a polycarbonate diol by subjecting a dihydroxy compound and a carbonic acid ester as raw material monomers to polycondensation by means of a transesterification reaction in the presence of a transesterification catalyst. The transesterification catalyst includes: a transesterification catalyst A1, which contains at least one type of metal (M1) selected from the group consisting of metals belonging to groups 6, 7, 8, 9, 10 and 11 of the long-form periodic table; and a transesterification catalyst A2, which contains at least one type of metal (M2) selected from the group consisting of metals belonging to groups 1 and 4 of the long-form periodic table.

Description

[Technical Field]

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

[0002] Conventionally, polyurethane resins and polyurea resins have been used in a wide range of applications, including synthetic leather, artificial leather, adhesives, furniture paints, and automotive paints. Polyethers and polyesters have been used as polyol components to react with isocyanates (see, for example, Patent Document 1 and Non-Patent Document 1). However, in recent years, there has been an increasing demand for resin resistance, such as heat resistance, weather resistance, hydrolysis resistance, mildew resistance, and oil resistance.

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

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

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

[0006] In the past, in the combination of ethylene carbonate and 1,6-hexanediol, in addition to tetra-n-butyl titanate, dibutyltin dilaurate, sodium acetate, lithium hydroxide, tin powder, and the like have been used as catalysts (see, for example, Patent Document 9).

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

[0008] In recent years, as a method for improving the color tone of polycarbonate diol under milder conditions, a method for producing polycarbonate diol using an ester exchange catalyst characterized by the presence of a salt of acetylacetone (or a salt of an acetylacetone derivative) of at least one metal selected from the group consisting of zinc and metals of Group 2 of the long periodic table has been disclosed (see, for example, Patent Document 11). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-95836 [Patent Document 2] Japanese Patent Application Laid-Open 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 Application Laid-Open No. 2012-46659 [Patent Document 8] International Publication No. 2006 / 088152 [Patent Document 9] Japanese Patent Publication No. 51-144492 [Patent Document 10] Japanese Patent Application Laid-Open No. 2013-010950 [Patent Document 11] Japanese Patent Application Publication No. 2020-125467 [Non-patent literature]

[0010] [Non-Patent Document 1] 'Fundamentals and Applications of Polyurethane', pages 96-106, edited by Katsuji Matsunaga, CMC Publishing Co., Ltd., published November 2006 Summary of the Invention [Problem to be solved by the invention]

[0011] In conventional techniques, in order to carry out a polycondensation reaction of various dihydroxy compounds with different reactivities, it is necessary to set the reaction temperature high or add a large amount of catalyst, which may cause discoloration or thermal degradation of polycarbonate or polyester. Therefore, there is room for improvement in the transesterification catalysts known in the art when it comes to producing various polycarbonate diols and polyesters.

[0012] For example, when a strong base such as an alkali metal or alkaline earth metal or an alkoxide thereof is used as a catalyst, the polycarbonate diol is likely to be discolored.

[0013] Furthermore, when a titanium compound is used as a catalyst, the catalyst activity is insufficient, and the production process tends to take a long time. A long reaction time promotes the formation of undesirable ether groups and vinyl groups. When polycarbonate diol or polyester is used as a polyurethane raw material, these groups can cause the weather resistance and heat resistance of the resulting polyurethane to be impaired, making them undesirable as polyurethane raw materials.

[0014] On the other hand, lead compounds and organotin compounds have recently been found to be harmful to the human body and have adverse effects on ecosystems, and therefore these compounds are not preferred as components remaining in polycarbonate diol or polyester.

[0015] Furthermore, when magnesium acetate, magnesium alkoxide, or magnesium acetylacetone is used as a catalyst, the polymerization activity is higher than that of a titanium compound, and an improvement in productivity is observed, but it is not sufficient, and therefore there is room for improvement in terms of coloration of the obtained polycarbonate diol or polyester and improvement in productivity.

[0016] Therefore, an object of the present invention is to provide a method for efficiently producing a polycarbonate diol (specifically, for example, under milder reaction conditions and in a short time). Another object of the present invention is to provide a polycarbonate diol that has excellent color tone, few ether bonds, and a high purity of terminal primary hydroxyl groups (OH), and a polyurethane that uses the polycarbonate diol and has excellent chemical resistance, heat resistance, and hydrolysis resistance. Another object of the present invention is to provide a highly active catalyst that efficiently produces a polycarbonate diol or polyester (specifically, for example, under milder reaction conditions and in a short time). [Means for solving the problem]

[0017] As a result of intensive research aimed at solving these problems, the present inventors have found that by using at least two transesterification catalysts containing specific metals when producing polycarbonate diols or polyesters by polycondensation through a transesterification reaction, polycarbonate diols or polyesters can be efficiently produced, thereby solving the above problems. Furthermore, they have also found polycarbonate diols with excellent color tone, few ether bonds, and high purity of terminal primary hydroxyl groups (OH), and polyurethanes using such polycarbonate diols that have excellent chemical resistance, heat resistance, and hydrolysis resistance.

[0018] That is, the gist of the present invention is as follows. [1] The method includes a step of polycondensing a dihydroxy compound and a carbonate ester as raw material monomers through an ester exchange reaction in the presence of an ester exchange catalyst to obtain a polycarbonate diol, The method for producing a polycarbonate diol comprises a transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals in Groups 6, 7, 8, 9, 10, and 11 of the long periodic table, and a transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Groups 1 and 4 of the long periodic table. [2] The 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 a halogen atom or may have an oxygen atom; R2 represents hydrogen or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R2 may be substituted with a halogen atom or may have an oxygen atom; 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 form periodic table; and n is 1, 2, or 3. The metal complex represented by formula (1) may also be an association of multiple metals.) [3] The method for producing a polycarbonate diol according to [1], wherein the transesterification catalyst A1 is a salt of at least one carboxylic acid 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 form periodic table, represented by the following formula (2), and / or a hydrate thereof: [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] The 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] The method for producing a polycarbonate diol according to any one of [1] to [4], wherein the metal (M1) is manganese. [6] The method for producing a polycarbonate diol according to any one of [1] to [5], wherein the transesterification catalyst A2 is an alcoholate of at least one alcohol and at least one metal (M2) selected from the group consisting of metals of Groups 1 and 4 of the long periodic table, represented by the following formula (3): [ka] (In the formula, R5 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R5 may be substituted with a halogen atom or may have an oxygen atom.) [7] The method for producing a polycarbonate diol according to any one of [1] to [6], wherein the metal (M2) is at least one metal selected from the group consisting of lithium, sodium, potassium, titanium, zirconium, and hafnium. [8] The method for producing a polycarbonate diol according to any one of [1] to [7], wherein the metal (M2) is lithium. [9] the amount of the transesterification catalyst A1, as the total amount of the metal (M1), is 0.5 ppm or more and 20 ppm or less based on the total amount of all dihydroxy compounds and carbonate esters; The method for producing a polycarbonate diol according to any one of [1] to [8], wherein the amount of the transesterification catalyst A2, as the total amount of the metal (M2), is 0.25 ppm or more and 10 ppm or less relative to the total amount of all dihydroxy compounds and carbonate esters.

[10] The method for producing a polycarbonate diol according to any one of [1] to [9], wherein the dihydroxy compound comprises at least one selected from the group consisting of an aliphatic dihydroxy compound having a structure represented by the following formula (4) and an alicyclic dihydroxy compound: [ka] (wherein R6 represents a divalent aliphatic or alicyclic hydrocarbon group having 2 to 20 carbon atoms).

[11] The method for producing a polycarbonate diol according to any one of [1] to

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

[12] A polycarbonate diol that satisfies the following formula (A): HO-R(OC=OOR)m-OH (A) (In formula (A), R represents a divalent aliphatic hydrocarbon group or alicyclic hydrocarbon group having 2 to 20 carbon atoms, and m is an integer of 2 or more and 600 or less.) The number average molecular weight is 250 or more and 100,000 or less, At least one metal (M1) selected from the group consisting of metals of Groups 6, 7, 8, 9, 10 and 11 of the long periodic table is contained in the polycarbonate diol in a total amount of 1 ppm or more and 25 ppm or less, and at least one metal (M2) selected from the group consisting of metals of Group 1 and Group 4 of the long periodic table is contained in the polycarbonate diol in a total amount of 0.5 ppm or more and 12.5 ppm or less, The Hazen color number measured in accordance with JIS-K0071-1 (1998) is 50 or less, the amount of ether bonds is 5 mol% or less, The purity of terminal primary hydroxyl groups (OH) is 97% or more. Polycarbonate diol.

[13] The polycarbonate diol according to

[12] , wherein the polycarbonate diol is a polycondensation product obtained by an ester exchange reaction between a dihydroxy compound and a carbonate ester.

[14] The polycarbonate diol according to

[12] or

[13] , wherein the metal (M1) is at least one metal selected from the group consisting of molybdenum, manganese, iron, cobalt, nickel, and copper, and the metal (M2) is at least one metal selected from the group consisting of lithium, sodium, potassium, titanium, zirconium, and hafnium.

[15] The polycarbonate diol according to any one of

[12] to

[14] , wherein the metal (M1) is manganese and the metal (M2) is lithium.

[16]

[17] A polyurethane containing the polycarbonate diol according to any one of

[12] to

[15] . The transesterification catalyst comprises at least two transesterification catalysts: a transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals in Groups 6, 7, 8, 9, 10, and 11 of the long-form periodic table; and a transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Groups 1 and 4 of the long-form periodic table.

[18] The transesterification catalyst according to

[17] , wherein the transesterification catalyst A1 is at least one metal complex represented by the following formula (1) and / or a hydrate thereof: [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 a halogen atom or may have an oxygen atom; R2 represents hydrogen or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R2 may be substituted with a halogen atom or may have an oxygen atom; 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 form periodic table; and n is 1, 2, or 3. The metal complex represented by formula (1) may also be an association of multiple metals.)

[19] The transesterification catalyst according to

[17] , wherein the transesterification catalyst A1 is a salt of at least one carboxylic acid 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 form periodic table, and / or a hydrate thereof, 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.)

[20] The transesterification catalyst according to any one of

[17] to

[19] , wherein the metal (M1) is at least one metal selected from the group consisting of molybdenum, manganese, iron, cobalt, nickel, and copper. [twenty one] The transesterification catalyst according to any one of

[17] to

[19] , wherein the metal (M1) is manganese. [twenty two] The transesterification catalyst according to any one of

[17] to

[21] , wherein the transesterification catalyst A2 is an alcoholate of at least one alcohol and at least one metal (M2) selected from the group consisting of metals of Groups 1 and 4 of the long form periodic table, as represented by the following formula (3): [ka] (In the formula, R5 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R5 may be substituted with a halogen atom or may have an oxygen atom.) [twenty three] The transesterification catalyst according to any one of

[17] to

[22] , wherein the metal (M2) is at least one metal selected from the group consisting of lithium, sodium, potassium, titanium, zirconium, and hafnium. [twenty four] The transesterification catalyst according to any one of

[17] to

[22] , wherein the metal (M2) is lithium. [Effects of the Invention]

[0019] According to the method for producing a polycarbonate diol of the present invention, for example, a polycarbonate diol or polyester can be efficiently produced under milder conditions than those of conventionally known techniques. Furthermore, according to the present invention, it is possible to provide a polycarbonate diol or polyester that has excellent color tone, few ether bonds, and high purity of terminal primary hydroxyl groups (OH), and a polyurethane that uses the polycarbonate diol or polyester and has excellent chemical resistance, heat resistance, and hydrolysis resistance. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention (hereinafter abbreviated as "the present embodiment") will be described in detail. Note that the present invention is not limited to the following embodiment, and various modifications can be made within the scope of the gist of the present invention.

[0021] [1. Method for producing polycarbonate diol] The method for producing a polycarbonate diol of the present embodiment includes a 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 comprises a transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals in Groups 6, 7, 8, 9, 10, and 11 of the long periodic table, and a transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Groups 1 and 4 of the long periodic table.

[0022] In the method for producing a polycarbonate diol of the present embodiment, by using at least two kinds of transesterification catalysts containing specific metals, a polycarbonate diol can be produced efficiently (specifically, for example, under milder reaction conditions and in a short time).

[0023] <1-1. Raw material monomer> The method for producing a polycarbonate diol of 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 the present embodiment, the dihydroxy compound serving as a raw material monomer is not particularly limited, and examples thereof include 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; thioether diols such as bishydroxyethyl thioether; 2-ethyl-1,6-hexanediol, 2-methyl-1,3-propanediol, 2,2-Dialkyl-substituted 1,3-propanediol such as 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, 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 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, and dihydroxy compounds containing a cyclic group 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 having a cyclic group in the molecule, such as hydroxyethylcyclohexane, isosorbide, spiroglycol, 2,5-bis(hydroxymethyl)tetrahydrofuran, 4,4'-isopropylidenedicyclohexanol, and 4,4'-isopropylidenebis(2,2'-hydroxyethoxycyclohexane); dihydroxy compounds having an aromatic ring, such as 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and 9,9-bis(4-(2-hydroxyethoxy-2-methyl)phenyl)fluorene; nitrogen-containing dihydroxy compounds, such as diethanolamine and N-methyl-diethanolamine; 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(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)methane, bis(4-hydroxy-5-nitro ... aromatic bisphenols such as bis(4-hydroxyphenyl)ethane, 3,3-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenyl sulfone, 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] Among them, from the viewpoint of weather resistance of the polyurethane obtained using the polycarbonate diol of the present embodiment, the dihydroxy compound is preferably at least one compound selected from the group consisting of aliphatic dihydroxy compounds and alicyclic dihydroxy compounds, and more preferably at least one compound selected from the group consisting of aliphatic dihydroxy compounds and alicyclic dihydroxy compounds represented by the following formula (4). [ka] (wherein R6 represents a divalent aliphatic or alicyclic hydrocarbon group having 2 to 20 carbon atoms).

[0026] Of these dihydroxy compounds, particularly preferred aliphatic dihydroxy compounds are 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, and 2-methyl-1,8-octanediol, and particularly preferred alicyclic dihydroxy compounds are 1,4-cyclohexanedimethanol and tricyclodecanedimethanol.

[0027] These dihydroxy compounds may be used alone or in combination of two or more depending on the required performance of the resulting polycarbonate diol, but it is preferable to combine a plurality of them to form a copolymer polycarbonate diol. Copolymer polycarbonate diols are generally inhibited from crystallizing and have higher fluidity than homopolycarbonate diols, which not only makes them easier to handle when processed into polyurethane but also imparts flexibility and texture to the polyurethane.

[0028] Regarding the composition ratio of the copolymerization, for example, when two kinds of dihydroxy compounds are used, 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, based on the total amount of dihydroxy compounds.

[0029] Usually, when dihydroxy compounds with different molecular structures are copolymerized, the polymerization reaction may become non-uniform or the polymerization may be inhibited due to differences in reactivity. However, according to the present embodiment, which uses a specific transesterification catalyst described below, a copolymerized polycarbonate diol can be easily obtained.

[0030] <1-1-2. Carbonate ester> In the method for producing a polycarbonate diol of the present embodiment, the carbonate ester that can be used as a raw material monomer is not limited as long as it does not impair the effects of the present invention, and examples thereof include dialkyl carbonate, diaryl carbonate, and alkylene carbonate.

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

[0032] Examples of diaryl carbonates include, but are not limited to, diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, and di-m-cresyl carbonate.

[0033] Examples of alkylene carbonates include, but are not limited to, 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, and neopentyl carbonate.

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

[0035] Among these carbonate esters, dimethyl carbonate, diethyl carbonate, ethylene carbonate, and diphenyl carbonate are particularly preferred because they are available inexpensively as industrial raw materials, have good reactivity, and produce only small amounts of alcohol as by-products.

[0036] <1-1-3. Usage ratio of raw material monomers> In the method for producing a polycarbonate diol 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 usually the lower limit in terms of molar ratio to 1 mole of the total of dihydroxy compounds is preferably 0.5, more preferably 0.7, and even more preferably 0.8, and the upper limit is usually 1.5, preferably 1.3, and more preferably 1.2. When the amount of carbonate diester used is equal to or less than the above upper limit, the proportion of the polycarbonate diol obtained having terminal groups other than hydroxyl groups can be suppressed, or there is a tendency that the polycarbonate diol of this embodiment having a molecular weight within a predetermined range can be produced, and when it is equal to or more than the above lower limit, there is a tendency that polymerization proceeds up to the predetermined molecular weight.

[0037] <1-2. Transesterification catalyst> The transesterification catalyst used in this embodiment includes at least two types of transesterification catalysts: a transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals in Groups 6, 7, 8, 9, 10, and 11 of the long periodic table; and a transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Groups 1 and 4 of the long periodic table.

[0038] <1-2-1. Transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals belonging to groups 6, 7, 8, 9, 10, and 11 of the long periodic table> One form of the transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals of Groups 6, 7, 8, 9, 10, and 11 of the long periodic table is preferably 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 a halogen atom or may have an oxygen atom; R2 represents hydrogen or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R2 may be substituted with a halogen atom or may have an oxygen atom; 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 form periodic table; and n is 1, 2, or 3. The metal complex represented by formula (1) may also be an association of multiple metals.)

[0039] The ligand to the metal of the metal complex represented by formula (1) is an acetylacetone analogue, and can be expressed in a form in which the anion is delocalized as shown in the following formula (7), but it can also be expressed as an equilibrium state of three types of organic anions as shown in the following formula (8). [ka] [ka] (In formula (7) and formula (8), R1 and R3 each independently represent a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R1 and R3 may be substituted with a halogen atom or may have an oxygen atom; R2 represents hydrogen or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R2 may be substituted with a halogen atom or may have an oxygen atom.)

[0040] Methods for preparing the transesterification catalyst represented by formula (1) include, but are not limited to, a method for preparing the transesterification catalyst represented by formula (1) by reacting a metal halide salt with an acetylacetone analogue in the presence of a base, as shown in the following formula (9), and a method for preparing the transesterification catalyst represented by formula (1) by exchanging a metal alkoxide with an acetylacetone analogue, as shown in the following formula (10). [ka] [ka] (In the above formulas (9) and (10), R1, R2, R3, M1, and n are defined as in the above formula (1), X is any halogen atom, and R8 is any hydrocarbon group.)

[0041] In addition, together with the transesterification catalyst represented by formula (1), it is also possible to use, as an auxiliary, a basic compound such as a transition metal compound, a basic boron compound, a basic phosphorus compound, a basic ammonium compound, or an amine compound.

[0042] R1 and R3 in formula (1) are not particularly limited, and examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, phenyl, benzyl, monofluoromethyl, difluoromethyl, trifluoromethyl, monochloromethyl, dichloromethyl, and trichloromethyl groups, among which methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, phenyl, benzyl, trifluoromethyl, and trichloromethyl groups are particularly preferred. R1 and R3 may be the same or different.

[0043] Furthermore, R2 is not particularly limited to, but examples thereof include hydrogen, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a cyclohexyl group, a phenyl group, a benzyl group, a monofluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a monochloromethyl group, a dichloromethyl group, a trichloromethyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like. Among these, hydrogen, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a 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 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] In the present embodiment, the organometallic complexes with these acetylacetone analogues used as transesterification catalysts can also be used as hydrates.

[0046] Another embodiment of the transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals in Groups 6, 7, 8, 9, 10, and 11 of the long periodic table is preferably a salt of at least one carboxylic acid and at least one metal (M1) selected from the group consisting of metals in Groups 6, 7, 8, 9, 10, and 11 of the long periodic table and / or a hydrate thereof, as 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 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] In the present 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 of Groups 1 and 4 of the long-form periodic table> The transesterification catalyst used in this embodiment contains at least two types of transesterification catalysts: the above-mentioned transesterification catalyst A1 and a transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals of Groups 1 and 4 of the long-form periodic table.

[0051] The metal of Group 1 of the long periodic table is not particularly limited, but examples thereof include lithium, sodium, potassium, rubidium, cesium, and francium. Among these, lithium, sodium, and potassium are preferred because of their high catalytic activity. Lithium is particularly preferred because it has particularly high activity and produces a polycarbonate diol with a small amount of ether bonds.

[0052] The metal of Group 4 of the long periodic table is not particularly limited, but examples thereof include titanium, zirconium, and hafnium. Among these, titanium is particularly preferred because it has high activity and produces a polycarbonate diol with a small amount of ether bonds.

[0053] The form of the transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals of Groups 1 and 4 of the long periodic table is not particularly limited, and examples thereof include salts with inorganic acids, salts with organic acids, alcoholates of various alcohols, and hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, and titanium hydroxide.

[0054] Among these, an alcoholate of at least one alcohol and at least one metal (M2) selected from the group consisting of metals of Groups 1 and 4 of the long periodic table, as represented by the following formula (3), is preferred because it has high catalytic activity and little coloration. [ka] (In the formula, R5 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R5 may be substituted with a halogen atom or may have an oxygen atom.)

[0055] The alcoholate of at least one alcohol and a metal of Group 1 of the long period periodic table, represented by formula (3), is not particularly limited, and examples thereof include lithium methylate (lithium methoxide), lithium ethylate (lithium ethoxide), lithium propoxide, lithium butoxide, sodium methylate (sodium methoxide), sodium ethylate (sodium ethoxide), sodium propoxide, sodium butoxide, potassium methylate (potassium methoxide), potassium ethylate (potassium ethoxide), potassium propoxide, potassium butoxide, rubidium methoxide, rubidium ethoxide, cesium methoxide, cesium ethoxide, etc. Among these alcoholates, lithium methylate, lithium ethylate, sodium methylate, and sodium ethylate are preferred, as they have high catalytic activity and produce polycarbonate diols with low ether bond content and low coloration, and lithium methylate and lithium ethylate are particularly preferred.

[0056] The alcoholate of at least one alcohol and a metal of Group 4 of the long periodic table, represented by formula (3), is not particularly limited, and examples thereof include tetraisopropoxytitanium, tetra-n-butoxytitanium, tetra-n-butoxyzirconium, tetra-n-butoxyhafnium, tetra-t-butoxyzirconium, tetra-t-butoxyhafnium, etc. Among these alcoholates, tetraisopropoxytitanium and tetra-n-butoxytitanium are preferred, as they have high catalytic activity and produce polycarbonate diols with a small amount of ether bonds and little coloration.

[0057] The transesterification catalyst used in this embodiment includes at least two types of transesterification catalysts: transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals in Groups 6, 7, 8, 9, 10, and 11 of the long periodic table; and transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Groups 1 and 4 of the long periodic table.

[0058] The combined use of the transesterification catalyst A1 and the transesterification catalyst A2 provides higher catalytic activity than the use of either the transesterification catalyst A1 or the transesterification catalyst A2 alone, and for example, allows for efficient production of polycarbonate diol.

[0059] Although the mechanism by which this effect is achieved is unclear, the present inventors speculate that it is due to the reaction mechanism shown in the following formula (13). First, transesterification catalyst A1, which contains at least one metal (M1) selected from the group consisting of metals in Groups 6, 7, 8, 9, 10, and 11 of the long-form 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 in Groups 1 and 4 of the long-form periodic table, is thought to anionize the oxygen of the alcohol and promote the reaction with the activated carbonyl carbon. [ka] (In the formula, 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-form periodic table; M2 represents at least one metal selected from the group consisting of metals of Groups 1 and 4 of the long-form periodic table; R 11 , R 12 , R 13 represents any hydrocarbon group, and L1 represents any ligand (there may be multiple ligands).

[0060] <How to use the catalyst> The method for using the transesterification catalyst of this embodiment is not particularly limited, but for example, when used to produce a polycarbonate diol, a method in which a dihydroxy compound and a carbonate ester are typically used as raw material monomers, the transesterification catalyst of this embodiment is added, and polycondensation is carried out by a transesterification reaction can be exemplified. Furthermore, when the transesterification catalyst of this embodiment is used to produce a polyester, a method in which a dihydroxy compound and a dibasic acid such as adipic acid or phthalic acid and / or their methyl esters or ethyl esters are typically used as raw material monomers, the transesterification catalyst of this embodiment is added, and polycondensation is carried out by a transesterification reaction can be exemplified. By using the transesterification catalyst of this embodiment, for example, polycarbonate diol or polyester can be produced efficiently (specifically, for example, under milder reaction conditions and in a short time). Taking the production of polycarbonate diol as an example, the specific method of using the transesterification catalyst of this embodiment is as described above.

[0061] The amount of transesterification catalyst used in this embodiment is such that the amount of transesterification catalyst A1, as the 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 all dihydroxy compounds and carbonate esters; and the amount of transesterification catalyst A2, as the 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 all dihydroxy compounds and carbonate esters.

[0062] When the amount of the transesterification catalyst A1 is 0.5 ppm or more in total as the metal (M1), the transesterification reaction rate tends to be faster. Also, when the amount of the transesterification catalyst is 20 ppm or less in total as the metal (M1), coloration of the obtained polycarbonate diol can be suppressed, and when used as a urethane raw material, the urethane-forming reaction tends to be stable, the color tone of the obtained urethane tends to be good, and the heat resistance tends to be improved.

[0063] When the amount of the transesterification catalyst A2 is 0.25 ppm or more in total as the metal (M2), the transesterification reaction rate tends to be faster. Also, when the amount of the transesterification catalyst is 10 ppm or less in total as the metal (M2), the coloring of the obtained polycarbonate diol can be suppressed, the number of ether bonds decreases, and when used as a urethane raw material, the urethane reaction tends to be stable, the color tone of the obtained urethane tends to be good, and the heat resistance tends to be improved.

[0064] <1-3. Method for producing polycarbonate diol> In this embodiment, one or more of the dihydroxy compounds described above and one or more of the carbonate esters described above are transesterified in the presence of at least two transesterification catalysts A1 and A2 described above to produce a polycarbonate diol.

[0065] <1-3-1. Reaction conditions, etc.> The method for charging the reaction raw materials is not particularly limited, and the method can be freely selected, for example, by charging all of one or more dihydroxy compounds, a carbonate ester, and a catalyst at the same time and subjecting them to the reaction; by first charging the carbonate ester when the carbonate ester is solid, heating it to melt it, and then adding the dihydroxy compound catalyst; or, conversely, by charging the dihydroxy compound when the dihydroxy compound is solid first, melting it, and then adding the carbonate ester and catalyst.

[0066] The reaction temperature during the transesterification reaction can be any temperature that allows a practical reaction rate to 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 equal to or higher than the lower limit, the transesterification reaction tends to proceed at a practical rate. When the reaction temperature is equal to or lower than the upper limit, coloration of the resulting polycarbonate diol can be suppressed, and the formation of ether bonds can be suppressed, and the quality tends to be improved, such as by improving turbidity.

[0067] In particular, the method for producing a polycarbonate diol of the present embodiment uses at least two transesterification catalysts A1 and A2 containing specific metals, and thereby can efficiently produce a polycarbonate diol in a short time under mild reaction conditions, for example, even at a low temperature of 160°C or lower (preferably 150°C or lower).

[0068] Although the reaction can be carried out at normal pressure, since the transesterification reaction is an equilibrium reaction, the reaction can be biased toward the product system by distilling off the produced monohydroxy compound or dihydroxy compound outside the system. Therefore, it is usually preferable to adopt reduced pressure conditions in the latter half of the reaction to carry out the reaction while distilling off the monohydroxy compound or dihydroxy compound. Alternatively, it is also possible to carry out the reaction while distilling off the produced monohydroxy compound or dihydroxy compound by gradually reducing the pressure during the reaction. When the pressure is gradually reduced during the reaction, the volatilization of low-boiling unreacted monomers can be suppressed, the yield tends to be improved, and a polycarbonate diol with a predetermined molecular weight is obtained, or in the case of copolymerization, a polycarbonate diol with a predetermined copolymerization composition ratio is obtained.

[0069] The pressure during the reaction is appropriately selected depending on the type of alcohol derived from the carbonate ester to be distilled, but for example, when the alcohol to be distilled has a relatively low boiling point such as methanol, the pressure in the reactor is preferably 5 kPa to atmospheric pressure, more preferably 7 kPa to 15 kPa. When the alcohol to be distilled has a relatively high boiling point such as ethylene glycol, the pressure in the reactor is preferably 1 to 10 kPa, more preferably 3 kPa to 7 kPa.

[0070] Furthermore, in order to prevent the distillation of raw materials in the early stage of the reaction, the reactor may be equipped with a rectification column having a theoretical plate number of 10 or more, preferably 15 or more, and more preferably 20 or more, so that the monohydroxy compound or dihydroxy compound produced by the reaction from the carbonate ester can be efficiently separated and distilled off while azeotroping the monohydroxy compound or dihydroxy compound produced by the reaction from the carbonate ester, or while refluxing and separating the raw material carbonate ester and dihydroxy compound. This is preferable because the raw material monomers charged are not lost and the quantitative ratio of the reagents can be accurately adjusted.

[0071] Furthermore, at the final stage of the reaction, it is preferable to switch to simple distillation and carry out the reaction at a higher degree of reduced pressure, since this allows by-products such as monohydroxy compounds or dihydroxy compounds, such as alcohols, diols, and phenols, residual monomers such as carbonate esters, and further cyclic carbonates (cyclic oligomers) which may cause turbidity to be efficiently distilled off.

[0072] The reaction pressure at the end of the reaction is not particularly limited, but the upper limit is usually preferably 5 kPa, more preferably 2 kPa, and even more preferably 1 kPa or less. In order to effectively distill off these low-boiling components, the reaction can also be carried out while passing a small amount of an inert gas such as nitrogen, argon, or helium into the reaction system.

[0073] When a carbonate ester or a dihydroxy compound having a low boiling point is used in the transesterification reaction, it is also possible to carry out the reaction at a temperature close to the boiling point of the carbonate diester or dihydroxy compound in the early stage of the reaction, and then gradually raise the temperature as the reaction proceeds to further promote the reaction. This is preferable because it is possible to prevent the distillation of unreacted carbonate diester or dihydroxy compound in the early stage of the reaction.

[0074] <1-3-2. Polymerization reactor> The polymerization reaction (polycondensation reaction) can be carried out either batchwise or continuously, but continuous reaction is preferred in terms of the stability of the product's quality, such as molecular weight. The apparatus used may be of any type, such as a tank, tube, or tower, and any known polymerization vessel equipped with various stirring blades can be used. There are no particular restrictions on the atmosphere during the temperature increase of the apparatus, but from the viewpoint of product quality, it is preferable to carry out the reaction in an inert gas such as nitrogen gas at normal or reduced pressure.

[0075] <1-3-3. Reaction time> In the method for producing the polycarbonate diol of the present embodiment, the time required for the transesterification reaction (polymerization reaction or polycondensation reaction) cannot be generally specified because it varies greatly depending on the types and amounts of the dihydroxy compound, carbonic acid diester, and transesterification catalyst used, but the reaction time required to reach a predetermined molecular weight is usually preferably 20 hours or less, more preferably 10 hours or less, and even more preferably 5 hours or less.

[0076] <1-3-4. Catalyst deactivation> As mentioned above, when a transesterification catalyst is used in the transesterification reaction, the resulting polycarbonate diol usually contains the transesterification catalyst or its residue, which can make it difficult to control the polyurethane-forming reaction. To suppress the effects of this residual catalyst, a catalyst deactivator, such as an acidic compound or a phosphorus- or sulfur-based compound that decomposes to an acidic compound, may be added in an amount approximately equimolar to the transesterification catalyst used. Furthermore, by carrying out a heat treatment after the addition, as described below, the transesterification catalyst can be efficiently deactivated. Furthermore, by deactivating the catalyst, color development due to the transesterification catalyst can be reduced, and a polycarbonate diol can be obtained having a Hazen color scale of preferably 50 or less, more preferably 30 or less, measured in accordance with JIS-K0071-1 (1998).

[0077] Furthermore, by adding a catalyst deactivator, coloration and changes in physical properties that occur due to changes in the terminal structure and skeleton of the polycarbonate diol and the remaining catalyst when the obtained polycarbonate diol composition is stored or handled at high temperature for a long period of time can be suppressed.

[0078] The compound used to inactivate the transesterification catalyst (hereinafter sometimes referred to as a catalyst deactivator) is not particularly limited, but examples thereof 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 acid, sulfonate esters, etc. These may be used alone or in combination of two or more.

[0079] The amount of catalyst deactivator used is not particularly limited, but as mentioned above, it is sufficient to use an amount approximately equimolar to the transesterification catalyst used. Specifically, the upper limit is preferably 5 mol, more preferably 2 mol, and the lower limit is preferably 0.8 mol, more preferably 1.0 mol, per mol of the transesterification catalyst used. When the catalyst deactivator is used in an amount equal to or greater than the lower limit, the transesterification catalyst in the reaction product is sufficiently deactivated, and when the resulting polycarbonate diol is used as, for example, a raw material for producing polyurethane, the reactivity of the polycarbonate diol with isocyanate groups tends to be sufficiently reduced. Furthermore, when the catalyst deactivator is used in an amount equal to or less than the upper limit, coloration of the resulting polycarbonate diol can be suppressed, and when used as a urethane raw material, urethane polymerization tends to proceed smoothly.

[0080] Inactivation of the transesterification catalyst by adding a catalyst deactivator can be carried out at room temperature, but heating is more efficient. The temperature of this heat 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 time required to deactivate the transesterification catalyst is shortened, which is efficient, 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, decomposition of the phosphorus-based compound can be suppressed, and deactivation tends to be stable. Therefore, coloration of the resulting polycarbonate diol can be suppressed, and when used as a urethane raw material, the urethane reaction tends to be stable.

[0081] The time for the reaction with the catalyst deactivator is not particularly limited, but is, for example, 1 to 5 hours.

[0082] <1-4. Physical properties of polycarbonate diol> The polycarbonate diol of this embodiment satisfies the following formula (A). HO-R(OC=OOR)m-OH (A) (In formula (A), R represents a divalent aliphatic or alicyclic hydrocarbon group having 2 to 20 carbon atoms, and m is an integer of 2 or more and 600 or less.) In formula (A), R is preferably a divalent aliphatic or alicyclic hydrocarbon group having 2 to 20 carbon atoms. Specific examples of R are not particularly limited, but include propylene, tetramethylene, pentamethylene, hexamethylene, nonamethylene, decamethylene, 2,2-dimethyl-1,3-propylene, 2-methyl-1,3-propylene, 3-methyl-pentamethylene, and 2-methyl-octamethylene. Examples of alicyclic hydrocarbon groups include 1,4-cyclohexanedimethylene and tricyclodecanedimethylene. Of these, propylene, tetramethylene, pentamethylene, and hexamethylene are preferred. In formula (A), m is preferably an integer of 2 to 600, more preferably an integer of 3 to 100, and even more preferably an integer of 5 to 30. The polycarbonate diol of the present embodiment is preferably a polycondensate obtained by an ester exchange reaction between a dihydroxy compound and a carbonate ester. Preferred physical properties of the polycarbonate diol of this embodiment will be described below.

[0083] <1-4-1.Molecular weight / molecular weight distribution> The lower limit of the number average molecular weight (Mn) of the polycarbonate diol of 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 of this embodiment is 100000, preferably 50000, more preferably 10000, and particularly preferably 3000. When the number average molecular weight of the polycarbonate diol is equal to or higher than the above lower limit, the flexibility and the like tend to be improved when the polycarbonate diol is made into a polyurethane. On the other hand, when the number average molecular weight of the polycarbonate diol is equal to or lower than the above upper limit, the viscosity of the polycarbonate diol decreases, and handling during polyurethane formation tends to be easier.

[0084] Here, the number average molecular weight of the polycarbonate diol is determined from the hydroxyl value (average hydroxyl value) of the polycarbonate diol, as shown in the examples below.

[0085] The method for controlling the number average molecular weight (Mn) of the polycarbonate diol within the above range is not particularly limited, but examples thereof include a method for controlling the number average molecular weight (Mn) of the polycarbonate diol within the above range by adjusting the polycondensation reaction time of the polycarbonate diol and adjusting the amount of the dihydroxy compound, which is a raw material monomer, to be withdrawn.

[0086] <1-4-2.APHA value> The color of the polycarbonate diol of this embodiment is preferably a value (hereinafter referred to as "APHA value") expressed as a Hazen color number (based on JIS K0071-1:1998) of 50 or less, more preferably 40 or less, even more preferably 30 or less, and particularly preferably 20 or less. The lower limit of the APHA value is not particularly limited, but is, for example, 0 or more. When the APHA value is 50 or less, the color tone of the polyurethane obtained using the polycarbonate diol as a raw material tends to be good, which improves commercial value and improves thermal stability.

[0087] The method for controlling the APHA value of the polycarbonate diol within the above range is not particularly limited, but examples thereof include a method in which the reaction temperature during the transesterification reaction is within the above-mentioned preferred temperature range, and a method in which the time required for the transesterification reaction (polymerization reaction or polycondensation reaction) is within the above-mentioned preferred range.

[0088] In this embodiment, the APHA value of the polycarbonate diol can be measured by the method described in the examples below.

[0089] <1-4-3. Metals contained in polycarbonate diol> The polycarbonate diol of the present embodiment preferably contains, as metals, at least one metal (M1) selected from the group consisting of metals in Groups 6, 7, 8, 9, 10, and 11 of the long periodic table, and at least one metal (M2) selected from the group consisting of metals in Groups 1 and 4 of the long periodic table.

[0090] The polycarbonate diol of this embodiment preferably contains at least one metal (M1) selected from the group consisting of metals of Groups 6, 7, 8, 9, 10, and 11 of the long periodic table in a total amount of 1 ppm or more and 25 ppm or less, more preferably 2 ppm or more and 15 ppm or less, and even more preferably 5 ppm or more and 10 ppm or less.

[0091] When the polycarbonate diol of this embodiment has a total metal (M1) content of 1 ppm or more, the APHA value is low, and when used as a urethane raw material, the urethane reaction rate tends to be improved. Also, when the polycarbonate diol of this embodiment has a total metal (M1) content of 25 ppm or less, coloration of the polycarbonate diol due to heating can be suppressed, and when used as a urethane raw material, the urethane reaction tends to be stable.

[0092] In the polycarbonate diol of the present embodiment, the metal (M1) contained therein is preferably at least one metal selected from molybdenum, manganese, iron, cobalt, nickel, and copper, and among these, manganese is particularly preferred.

[0093] These metals contained in the polycarbonate diol may be present as residues of the polymerization catalyst, but may also be intentionally added in a predetermined amount after production.

[0094] The polycarbonate diol of this embodiment preferably contains at least one metal (M2) selected from the group consisting of metals of Groups 1 and 4 of the long 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.

[0095] When the polycarbonate diol of this embodiment has a total metal (M2) content of 0.5 ppm or more, the APHA value is low, and when used as a urethane raw material, the urethane reaction rate tends to be improved. Also, when the polycarbonate diol of this embodiment has a total metal (M2) content of 12.5 ppm or less, the amount of ether bonds is low, and coloration of the polycarbonate diol due to heating can be suppressed, and when used as a urethane raw material, the urethane reaction tends to be stable.

[0096] In the polycarbonate diol of this embodiment, the metal (M2) contained is preferably at least one metal selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, francium, titanium, zirconium, and hafnium. Among these, at least one metal selected from the group consisting of lithium, sodium, potassium, titanium, zirconium, and hafnium is more preferred, at least one metal selected from the group consisting of lithium, sodium, potassium, and titanium is even more preferred, and lithium is particularly preferred.

[0097] These metals contained in the polycarbonate diol may be present as residues of the polymerization catalyst, but may also be intentionally added in a predetermined amount after production.

[0098] <1-4-4. Ether bond> The polycarbonate diol of this embodiment has a basic structure in which a dihydroxy compound is polymerized via a carbonate group. However, depending on the production method, ether bonds may be formed due to side reactions such as the dehydration of some dihydroxy compounds or the decarboxylation of carbonate esters. If the amount of ether bonds present increases, weather resistance and heat resistance may decrease. Therefore, it is preferable to produce the polycarbonate diol so that the proportion of ether bonds is not excessively high. In order to reduce the 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 terms of mole percentage. These values ​​can be determined by alkaline hydrolysis followed by gas chromatography. Specifically, they can be measured by the method described in the Examples below.

[0099] The method for controlling the amount of ether bonds contained in the polycarbonate diol to be within the above range is not particularly limited, but examples thereof include a method for producing the polycarbonate diol under milder reaction conditions in a short time using the transesterification catalyst of the present application.

[0100] <1-4-5. Terminal primary hydroxyl group (OH) ratio> The terminal primary hydroxyl (OH) purity of the polycarbonate diol of this embodiment is preferably 97% or more, more preferably 98% or more, and even more preferably 99% or more. When the terminal primary hydroxyl (OH) purity is 97% or more, the reaction rate tends to be high when producing (synthesizing) polyurethane (particularly thermoplastic polyurethane) using the polycarbonate diol of this embodiment as a raw material compound, and the strength of the obtained polyurethane tends to be high.

[0101] In this embodiment, by using the above-mentioned transesterification catalysts A1 and A2, the reaction time can be shortened and polycarbonate diol can be produced under mild reaction conditions, so that a high purity of terminal primary hydroxyl groups (OH) can be achieved.

[0102] In this embodiment, the terminal primary hydroxyl (OH) purity of the polycarbonate diol can be measured by the method described in the examples below.

[0103] <1-5. Uses of Polycarbonate Diol> The polycarbonate diol of this embodiment has excellent mechanical properties and durability and can be used in a variety of applications. For example, it can be widely used in foams, elastomers, paints, fibers, adhesives, flooring materials, sealants, medical materials, artificial leather, coating agents, water-based polyurethane paints, etc. In particular, when the polycarbonate diol of this embodiment is used as a raw material for applications such as artificial leather, synthetic leather, water-based polyurethane, adhesives, medical materials, flooring materials, and coating agents, it has excellent weather resistance, heat resistance, moist heat resistance, and abrasion resistance, and can impart good surface properties such as little coloring, resistance to scratches and the like, and little deterioration due to friction, making it suitable for use as a raw material for various coatings.

[0104] The polyurethane of this embodiment contains the above-described polycarbonate diol. By containing the above-described polycarbonate diol, the polyurethane of this embodiment has excellent chemical resistance, heat resistance, and hydrolysis resistance. [Example]

[0105] The present embodiment will be described in more detail below using examples, but the present embodiment is not limited to these examples. Note that the number of parts in the examples is by mass unless otherwise specified.

[0106] In the following examples and comparative examples, the physical properties of the polycarbonate diol and polyurethane film were tested according to the following test methods.

[0107] <Test Method> [Evaluation of transesterification catalyst performance] In the production of polycarbonate diol (PCD) from a dihydroxy compound and a carbonate ester, for example, as shown in the following formula (14), the monomer raw materials, carbonate ester (e.g., ethylene carbonate (EC)) and dihydroxy compound (raw material diol), decrease in the esterification step, polycarbonate diol (PCD) is produced, and a hydroxy compound derived from the carbonate ester (a monohydroxy compound when the raw material carbonate ester is a dialkyl carbonate, or a dihydroxy compound when the raw material carbonate ester is an alkylene carbonate, e.g., ethylene glycol (EG)) is produced as a by-product. [ka] (Here, an example is shown in which ethylene carbonate (EC) is used as the carbonate ester. In this case, ethylene glycol (EG) is produced as a by-product of the reaction.) To evaluate the catalytic performance, in the reaction of producing polycarbonate diol (PCD) from a dihydroxy compound and a carbonate ester, the amount of hydroxy compound (monohydroxy compound when the raw material carbonate ester is dialkyl carbonate, or dihydroxy compound when the raw material carbonate ester is alkylene carbonate, for example, ethylene glycol (EG)) distilled out 1 hour and 2 hours after the start of the reaction was determined by gas chromatography, and the carbonate conversion was calculated using the following formula (15), (16), or (17). (Calculation method of carbonate conversion rate when alkylene carbonate is used) Carbonate conversion rate (%) = (number of moles of dihydroxy compound distilled) / (number of moles of charged carbonate ester) × 100 (15) (Calculation method of carbonate conversion rate when using dialkyl carbonate) Carbonate conversion rate (%) = (moles of distilled hydroxy compound / 2) / (moles of charged carbonate ester) × 100 (16) (Calculation method for carbonate conversion rate when diphenyl carbonate is used) Carbonate conversion rate (%) = (moles of distilled phenol / 2) / (moles of charged carbonate ester) × 100 (17) The conditions for gas chromatographic analysis were as follows: A gas chromatograph GC-14B (Shimadzu Corporation) equipped with a DB-WAX (J&W) column was used, 1,3-propanediol was used as the internal standard, and an FID detector was used. The column temperature profile was maintained at 100°C for 5 minutes, followed by a temperature increase at 5°C / min to 200°C. The reaction rate in the synthesis of polyester diol was calculated from the amount of alcohol distilled off by the reaction (for example, methanol when dimethyl dibasic acid is used as the raw material) using the following formula (17)'. (Reaction rate) = (moles of distilled alcohol / 2) / (moles of charged dibasic acid ester) × 100 (17)'

[0108] [Hydroxyl (OH) value measurement] An acetylation reagent was prepared by diluting 12.5 g of acetic anhydride with 50 mL of pyridine. 2.5 to 5.0 g of sample was precisely weighed into a 100 mL recovery flask. 5 mL of the acetylation reagent and 10 mL of toluene were added to the recovery flask using a volumetric pipette. A condenser was then attached, and the solution in the recovery flask was stirred and heated at 100°C for 1 hour. 2.5 mL of distilled water was added to the recovery flask using a volumetric pipette, and the solution in the recovery flask was heated and stirred for an additional 10 minutes. After cooling the solution in the recovery flask for 2 to 3 minutes, 12.5 mL of ethanol was added. Two to three drops of phenolphthalein were added to the recovery flask as an indicator, and the solution in the recovery flask was then titrated with 0.5 mol / L ethanolic potassium hydroxide. 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 recovery flask, heated and stirred for 10 minutes, and then titrated in the same manner as above. Based on this result, the OH value was calculated using the following formula (18). OH number (mg-KOH / g) = {(ba) × 28.05 × f} / e (18) a: Sample titer (mL) b: Titration volume of blank test (mL) e: Sample mass (g) f: factor of titrant

[0109] [Number average molecular weight (Mn)] The number average molecular weight was calculated by the following formula (19). Number average molecular weight = 2 / (OH value × 10 -3 / 56.11) (19)

[0110] [APHA value measurement] According to JIS K0071-1, the Hazen color number (APHA value) was measured by comparing 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. [Method for analyzing the amount of ether bonds in polycarbonate diol] 1 g of polycarbonate diol was placed in a 100 mL recovery flask, and 30 g of methanol and 8 g of 28% sodium methoxide methanol solution were added and reacted at 100 °C for 1 hour. After cooling to room temperature, 2–3 drops of phenolphthalein were added as an indicator and neutralized with hydrochloric acid. The neutralized reaction solution was cooled in a refrigerator for 1 hour and then filtered. The filtrate was then analyzed by gas chromatography (GC). GC analysis was performed using a gas chromatograph GC-14B (Shimadzu Corporation, Japan) equipped with a DB-WAX (J&W, USA) column. 1,3-propanediol was used as the internal standard and a flame ionization detector (FID) was used as the detector to quantitatively analyze each component. The column temperature profile was maintained at 110 °C for 5 minutes, followed by a temperature increase of 5 °C / min to 200 °C. Ether bonds are thought to be generated by the dehydration reaction of hydroxyl groups or the decomposition (decarboxylation) of carbonate esters. For example, when polycarbonate diol is produced using ethylene carbonate and hexanediol as raw materials, diethylene glycol and 6-(2-hydroxyethoxy)hexan-1-ol are detected as compounds having ether bonds.

[0111] [Method for analyzing the terminal primary hydroxyl group (OH) ratio of polycarbonate diol] 70g to 100g of polycarbonate diol was weighed into a 300ml recovery flask, and using a rotary evaporator connected to a trap bulb for fraction collection, the mixture was heated in a heating bath at approximately 180°C under a pressure of 0.1kPa or less and stirred, to obtain a fraction equivalent to approximately 1 to 2% by mass of the polycarbonate diol, i.e., approximately 1g (0.7 to 2g) of fraction, in the trap bulb. This fraction was collected using approximately 100g (95 to 105g) of ethanol as a solvent. The collected solution was analyzed by gas chromatography (hereinafter referred to as GC analysis), and the terminal primary hydroxyl (OH) ratio (%) of the polycarbonate diol was calculated from the peak area of ​​the obtained chromatograph using the following formula (20): GC analysis was performed using a Gas Chromatography 6890 (Hewlett-Packard, USA) equipped with a 30 m DB-WAX (J&W, USA) column with a 0.25 μm film thickness and a flame ionization detector (FID). The column temperature was raised from 60 °C to 250 °C at a rate of 10 °C / min, and then held at that temperature for 15 min. Identification of each peak in the GC analysis was performed using the following GC-MS system. The GC system used was a 6890 (Hewlett-Packard, USA) equipped with a DB-WAX (J&W, USA) column. The GC system was heated from an initial temperature of 40°C to 220°C at a rate of 10°C / min. The MS system used was an Auto-mass SUN (JEOL, Japan). The ionization voltage was 70 eV, the scan range was m / z = 10–500, and the photomultiplier gain was 450 V. Terminal primary OH ratio (%)=B÷A×100 (20) A: Sum of peak areas of alcohols (excluding ethanol) including diols B: Sum of peak areas of diols with primary OH groups at both ends

[0112] [Residual catalyst amount in polycarbonate diol] Approximately 0.1 g of polycarbonate diol was weighed out 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 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 the 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 shown below. The concentrations of various metals remaining in the polycarbonate diol were determined using previously prepared calibration curves for various metals. High-performance liquid chromatograph (HPLC) measurement conditions Apparatus: Waters 2690 Column: IonPac CS12A Flow rate: 1.0ml / min Injection amount: 1.5ml Pressure: 950~980psi Column temperature: 35℃ Detector sensitivity: RANGE 200μS Suppressor: CSRS 60mA Eluent: 20mmol / l methanesulfonic acid aqueous solution

[0113] [Measurement of the molecular weight of polyurethane] A portion of the polyurethane film was cut out, and an N,N-dimethylacetamide (DMF) solution was prepared so that the polyurethane concentration was 0.1% by mass. Using the prepared DMF solution, the molecular weights of the polyurethanes were measured as follows. A GPC system (manufactured by Tosoh Corporation, product name "HLC-8320" (column: Tskgel SuperHM-H x 4) was used for the measurement. The eluent used was a solution of 2.6 g of lithium bromide dissolved in 1 L of dimethylacetamide. The number-average molecular weight (Mn) of the polyurethane, calculated in terms of standard polystyrene, was calculated from the measurement results.

[0114] [Room temperature tensile test of polyurethane film] According to JIS K6301 (2010), rectangular test pieces measuring 10 mm in width, 100 mm in length, and approximately 0.5 mm in thickness were prepared from polyurethane film. A tensile test was performed on the prepared test pieces using a tensile testing machine (manufactured by 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 of 55%). In this tensile test, the stress at 100% elongation of the test piece (100% modulus), as well as the strength at break and elongation at break, were measured.

[0115] [Evaluation of polyurethane resistance to oleic acid] A 3cm x 3cm test piece was cut from the polyurethane film. The mass of the test piece was measured using a precision balance. The test piece was then placed in a 250mL glass bottle containing 50mL of oleic acid as the test solvent and left to stand in a constant temperature bath under a nitrogen atmosphere at 80°C for 16 hours to conduct a chemical resistance test. After the test, the test piece was removed and the front and back were lightly wiped with a paper wiper. The mass of the test piece was then measured using a precision balance. The mass change rate (increase rate) from before the test was calculated using the following formula. A mass change rate closer to 0% indicates better oleic acid resistance (chemical resistance). Mass change rate (%) = (mass of test piece after test - mass of test piece before test) / mass of test piece before test × 100

[0116] [Evaluation of polyurethane heat resistance] A rectangular test piece measuring 10 mm wide, 100 mm long, and approximately 50 μm thick was prepared from the polyurethane film. The test piece was heated in a gear oven at 120°C for 1000 hours. After heating, the test piece was measured for breaking strength in the same manner as in the room temperature tensile test described above. The breaking strength retention (%) was calculated using the following formula: Breaking strength retention rate (%) = Breaking strength of test piece after heating / Breaking strength of test piece before test × 100

[0117] [Evaluation of hydrolysis resistance of polyurethane] A rectangular test piece measuring 10 mm wide, 100 mm long, and approximately 50 μm thick was prepared from the polyurethane film. The test piece was heated in a thermo-hygrostat at a temperature of 85°C and a relative humidity of 85% for 200 hours. After heating, the test piece was measured for breaking strength in the same manner as in the room temperature tensile test described above. The breaking strength retention (%) was calculated using the following formula: Breaking strength retention rate (%) = Breaking strength of test piece after heating / Breaking strength of test piece before test × 100

[0118] [Compound abbreviation] 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-heptanedionatomanganese(II) dihydrate Mn(CF3COCH2COCF3)2·2H2O: Manganese hexafluoroacetylacetonate dihydrate [Mo(acac)]2: Molybdenum(II) acetylacetonate dimer Mg(acac)2·2H2O: Magnesium(II) acetylacetonate dihydrate 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 Mg(acac)2: Magnesium(II) acetylacetonate Li-OMe: Lithium methoxide Na-OMe: Sodium methoxide K-OMe: Potassium methoxide Li-t-OBu: Lithium t-butoxide 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

[0119] [Example 1] A 1-L separable flask equipped with a stirrer, thermometer, and vacuum-jacketed Oldershaw reactor (15 theoretical plates) with a reflux head on top was charged with 355 g (3.00 mol) of 1,6-hexanediol as raw monomers and 264 g (3.00 mol) of ethylene carbonate as raw materials. Catalysts included 16.3 mg of Mn(acac)2·2H2O and 6.7 mg of Li-OMe. The raw materials in the flask were heated in an oil bath set to 170 °C. The internal temperature of the flask was 150 °C, and the vacuum level was 4 kPa. The raw material monomers were polycondensed by transesterification for 2 hours while a portion of the distillate was removed from the reflux head. Polycarbonate diol was obtained. The carbonate conversion was analyzed by gas chromatography 1 hour and 2 hours after the start of the reaction. The ether bond content was also measured 2 hours after the start of the reaction. The results are shown in Table 1.

[0120] [Example 2~ 12、 14. See Example 1 for reference. Comparative Examples 1 to 5 A polycarbonate diol was obtained by polycondensing raw material monomers through transesterification in the same manner as in Example 1, except that the type and amount of catalyst added were the type and amount shown in Table 1. As in Example 1, the carbonate conversion was analyzed by gas chromatography 1 hour and 2 hours after the start of the reaction. In addition, the amount of ether bond 2 hours after the start of the reaction was measured. The results are shown in Table 1.

[0121] Example 1A A 1-L separable flask equipped with a stirrer, thermometer, and vacuum-jacketed Oldershaw reactor (15 theoretical plates) with a reflux head on top was charged with 523 g (3.00 mol) of dimethyl adipate and 270 g (3.00 mol) of 1,4-butanediol as raw monomers, and 17.7 mg of Mn(OAc)2·4H2O and 8.6 mg of Li-OMe as catalysts. The raw monomers were heated in an oil bath set to 170 °C. The internal temperature of the flask was 150 °C and the polycondensation reaction proceeded at atmospheric pressure for 2 hours while a portion of the distillate was withdrawn through the reflux head, yielding a polyester diol. Carbonate conversion was analyzed by gas chromatography 1 and 2 hours after the start of the reaction. The results are shown in Table 1-1.

[0122] [Comparative Examples 1B, 2B] The raw material monomers were polycondensed by transesterification to obtain a polyester diol in the same manner as in Example 1A, except that the type and amount of catalyst added were the type and amount shown in Table 1-1. As in Example 1A, the carbonate conversion was analyzed by gas chromatography 1 hour and 2 hours after the start of the reaction. The results are shown in Table 1-1.

[0123] [Table 1]

[0124] [Table 1-1]

[0125] [Examples 15 to 25] A polycarbonate diol was obtained by polycondensing raw material monomers through transesterification in the same manner as in Example 1, except that the type and amount of catalyst added were the type and amount shown in Table 2 and the reaction temperature was the temperature shown in Table 2. As in Example 1, the carbonate conversion was analyzed by gas chromatography 1 hour and 2 hours after the start of the reaction. In addition, the amount of ether bonds and APHA were measured 2 hours after the start of the reaction. The results are shown in Table 2.

[0126] [Table 2]

[0127] [Examples 26 to 29, Comparative Examples 6 and 7] A polycarbonate diol was obtained by polycondensing raw material monomers through transesterification in the same manner as in Example 1, except that the type and amount of catalyst added and the type of carbonate ester used were as shown in Table 3. The carbonate conversion rates were analyzed by gas chromatography 1 hour and 2 hours after the start of the reaction, as in Example 1. The results are shown in Table 3.

[0128] [Table 3]

[0129] [Examples 30 to 37] A polycarbonate diol was obtained by polycondensing raw material monomers through transesterification in the same manner as in Example 1, except that the type and amount of catalyst added and the type and amount of dihydroxy compound used were changed to those shown in Table 4. As in Example 1, the carbonate conversion was analyzed by gas chromatography 1 hour and 2 hours after the start of the reaction. The results are shown in Table 4.

[0130] [Table 4]

[0131] [Example 38] A 1-L separable flask equipped with a stirrer, thermometer, and vacuum-jacketed Oldershaw column (15 theoretical plates) with a reflux head on top was charged with 355 g (3.00 mol) of 1,6-hexanediol and 264 g (3.00 mol) of ethylene carbonate. 13.8 mg of Mn(OAc)2·4H2O and 6.7 mg of Li-OMe were added as catalysts. The materials in the flask were heated in an oil bath set to 170 °C. The internal temperature of the flask was 150 °C, and the vacuum level was 4 kPa. While removing a portion of the distillate through the reflux head, the raw material monomers were polycondensed by transesterification to obtain polycarbonate diol for 2 hours. The carbonate conversion at this point (2 hours after the start of the reaction) was measured. The results are shown in Table 5. The reaction was then switched to simple distillation, and the pressure was gradually reduced to 0.5 kPa. The oil bath temperature was set to 175°C, and the reaction was carried out for 1 hour at an internal flask temperature of 160°C, and the monomer was distilled to obtain a polycarbonate diol. Nitrogen gas was introduced to return the pressure to normal, and then the oil bath temperature was set to 125°C, and the internal flask temperature was set to 110-120°C. Monobutyl phosphate was added as a catalyst deactivator in an amount equimolar to the amount of catalyst charged, and the mixture was stirred at a temperature of 110-120°C for 3 hours. The analysis results of the obtained polycarbonate diol are shown in Table 5. This polycarbonate diol is referred to as PC1.

[0132] [Examples 39 to 41] Polycarbonate diols were obtained by polycondensing raw material monomers through transesterification in the same manner as in Example 38, except that the types and amounts of dihydroxy compounds used were as shown in Table 5. The carbonate conversion rate 2 hours after the start of the reaction and the properties of the obtained polycarbonate diols are shown in Table 5. The obtained polycarbonate diols are referred to as PC2, PC3, and PC4, respectively.

[0133] [Example 42] A polycarbonate diol was obtained by polycondensing raw material monomers through transesterification in the same manner as in Example 41, except that the type and amount of dihydroxy compound used were as shown in Table 5 and the reaction time after switching to simple distillation was 0.5 hours. The carbonate conversion rate 2 hours after the start of the reaction and the properties of the obtained polycarbonate diol are shown in Table 5. The obtained polycarbonate diol is referred to as PC5.

[0134] [Example 43] A polycarbonate diol was obtained by polycondensing raw material monomers through transesterification in the same manner as in Example 41, except that the type and amount of dihydroxy compound used were as shown in Table 5 and the reaction time after switching to simple distillation was 2 hours. The carbonate conversion rate 2 hours after the start of the reaction and the properties of the obtained polycarbonate diol are shown in Table 5. The obtained polycarbonate diol is called PC6.

[0135] [Comparative Example 8] A 1-L separable flask equipped with a vacuum jacket and Oldershaw reactor (15 theoretical plates) with a stirrer, thermometer, and reflux head on top was charged with 156 g of 1,5-pentanediol, 177 g of 1,6-hexanediol, and 264 g (3.00 mol) of ethylene carbonate as raw monomers, and 13.8 mg of Mn(OAc)2·4H2O as catalyst. The raw materials in the flask were heated in an oil bath set to 170°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 distillate was withdrawn through the reflux head. (A portion of the reaction mixture was withdrawn two hours after the start of the reaction, and the carbonate conversion after two hours was determined.) The reaction was then switched to simple distillation, and the pressure was gradually reduced to 0.5 kPa. The oil bath temperature was set to 180°C, and the reaction was carried out for 4 hours at an internal flask temperature of 160-170°C, during which the monomer was distilled off to obtain polycarbonate diol. After introducing nitrogen gas to return to normal pressure, the oil bath temperature was set to 125°C, and the internal temperature of the flask was set to 110-120°C. As a catalyst deactivator, monobutyl phosphate was added in an amount equimolar to the amount of catalyst charged, and the mixture was stirred at a temperature of 110-120°C for 3 hours. The analysis results of the obtained polycarbonate diol are shown in Table 5. This polycarbonate diol is called PC7.

[0136] Comparative Example 9 A 1-L separable flask equipped with a stirrer, thermometer, and vacuum-jacketed Oldershaw reactor (15 theoretical plates) with a reflux head on top was charged with 156 g of 1,5-pentanediol, 177 g of 1,6-hexanediol, and 264 g (3.00 mol) of ethylene carbonate as raw monomers, and 6.7 mg of Li-OMe was added as a catalyst. The raw materials in the flask were heated in an oil bath set to 170°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 distillate was withdrawn through the reflux head. (A portion of the reaction solution was withdrawn two hours after the start of the reaction, and the carbonate addition rate after two hours was determined.) The reaction was then switched to simple distillation, and the pressure was gradually reduced to 0.5 kPa. The oil bath temperature was set to 180°C, and the reaction was carried out for 4 hours at an internal flask temperature of 160-170°C, and the monomer was distilled off to obtain polycarbonate diol. After introducing nitrogen gas to return to normal 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 amount equimolar to the amount of catalyst charged, and the mixture was stirred at a temperature of 110-120°C for 3 hours. The analysis results of the obtained polycarbonate diol are shown in Table 5. This polycarbonate diol is referred to as PC8.

[0137] [Comparative Example 10] Except for changing the amount of Li-OMe to 33.5 mg, the raw material monomers were polycondensed by transesterification to obtain a polycarbonate diol in the same manner as in Comparative Example 9. The carbonate conversion rate after 2 hours from the start of the reaction and the properties of the obtained polycarbonate diol are shown in Table 5. The obtained polycarbonate diol is referred to as PC9.

[0138] [Table 5]

[0139] [Example 44] A 200 mL separable flask equipped with a stirring blade, heated in a 60°C oil bath and sealed with nitrogen, 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 a solvent, and 0.003 g of dibutyltin dilaurate as a catalyst. A solution of 42 g of polycarbonate diol PC1 and 60 g of DMF, preheated to 60°C, was added dropwise using a dropping funnel over approximately 1 hour to obtain a solution. The resulting 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 for an additional 3 hours at 60°C, and then 1 g of ethyl alcohol was added to quench the reaction. The resulting polyurethane solution was applied to a polypropylene resin sheet (100 mm wide, 1200 mm long, 1 mm thick) using an applicator to a width of 80 mm, length of 100 mm, and thickness of 0.6 mm to obtain a coating film. The resulting coating film was dried on a hot plate at a surface temperature of 60°C for 2 hours, and then dried in an oven at 100°C for 12 hours. The film was then left to stand at a constant temperature and humidity of 23°C and 55% RH for at least 48 hours to obtain a polyurethane film. The resulting polyurethane film was then subjected to evaluation of various physical properties. The evaluation results are shown in Table 6.

[0140] [Examples 45 to 49, Comparative Examples 11 to 13] Polyurethane films were obtained in the same manner as in Example 44, except that PC2 to PC9 were used as the polycarbonate diols and the amounts of MDI and 14BDO were changed to those shown in Table 6. The obtained polyurethane films were subjected to evaluation of various physical properties. The evaluation results are shown in Table 6.

[0141] [Table 6]

[0142] This application is based on a Japanese patent application filed on January 18, 2022 (Patent Application No. 2022-005675) and a Japanese patent application filed on July 7, 2022 (Patent Application No. 2022-109959), the contents of which are incorporated herein by reference.

Claims

1. The method includes a step of polycondensing a dihydroxy compound and a carbonate ester as raw material monomers through an ester exchange reaction in the presence of an ester exchange catalyst to obtain a polycarbonate diol, The transesterification catalyst comprises a transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals in Groups 6, 7, 8, 9, 10, and 11 of the long periodic table, and a transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Group 1 of the long periodic table, The transesterification catalyst A1 is at least one metal complex and / or a hydrate thereof represented by the following formula (1): A method for producing a polycarbonate diol, wherein the transesterification catalyst A2 is an alcoholate of at least one alcohol and at least one metal (M2) selected from the group consisting of metals in Group 1 of the long form periodic table, represented by the following formula (3): 【Chemistry 1】 (In the formula, R 1 and R 3 each independently represent a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon groups of R 1 and R 3 may be substituted with a halogen atom or may have an oxygen atom; R 2 represents hydrogen or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R 2 may be substituted with a halogen atom or may have an oxygen atom; 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 form periodic table; and n is 1, 2, or 3. The metal complex represented by formula (1) may also be an association of multiple metals.) 【Transformation 3】 (wherein R 5 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R 5 may be substituted with a halogen atom or may have an oxygen atom.)

2. A method for producing a polycarbonate diol by polycondensing a dihydroxy compound and a carbonate ester as raw material monomers through an ester exchange reaction in the presence of an ester exchange catalyst, The transesterification catalyst comprises a transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals in Groups 6, 7, 8, 9, 10, and 11 of the long periodic table, and a transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Group 1 of the long periodic table, the transesterification catalyst A1 is a salt of at least one carboxylic acid 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 form periodic table, and / or a hydrate thereof, represented by the following formula (2): A method for producing a polycarbonate diol, wherein the transesterification catalyst A2 is an alcoholate of at least one alcohol and at least one metal (M2) selected from the group consisting of metals in Group 1 of the long form periodic table, represented by the following formula (3): 【Chemistry 2】 (In the formula, R 4 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R 4 may be substituted with a halogen atom or may have an oxygen atom.) 【Transformation 3】 (wherein R 5 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R 5 may be substituted with a halogen atom or may have an oxygen atom.)

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

4. The method for producing a polycarbonate diol according to claim 1 or 2, wherein the metal (M1) is manganese.

5. The method for producing a polycarbonate diol according to claim 1 or 2, wherein the metal (M2) is at least one metal selected from the group consisting of lithium, sodium, and potassium.

6. The method for producing a polycarbonate diol according to claim 1 or 2, wherein the metal (M2) is lithium.

7. the amount of the transesterification catalyst A1, as the total amount of the metal (M1), is 0.5 ppm or more and 20 ppm or less based on the total amount of all dihydroxy compounds and carbonate esters; 3. The method for producing a polycarbonate diol according to claim 1 or 2, wherein the amount of the transesterification catalyst A2, as the total amount of the metal (M2), is 0.25 ppm or more and 10 ppm or less based on the total amount of all dihydroxy compounds and carbonate esters.

8. 3. The method for producing a polycarbonate diol according to claim 1 or 2, wherein the dihydroxy compound comprises at least one selected from the group consisting of an aliphatic dihydroxy compound having a structure represented by the following formula (4) and an alicyclic dihydroxy compound: 【Chemistry 4】 (In the formula, R 6 represents a divalent aliphatic or alicyclic hydrocarbon group having 2 to 20 carbon atoms.

9. 3. The method for producing a polycarbonate diol according to claim 1 or 2, wherein the carbonate ester is at least one selected from the group consisting of alkylene carbonate, dialkyl carbonate, and diaryl carbonate.

10. A polycarbonate diol that satisfies the following formula (A): HO-R(OC=OOR)m-OH (A) (In formula (A), R represents a divalent aliphatic hydrocarbon group or alicyclic hydrocarbon group having 2 to 20 carbon atoms, and m is an integer of 2 or more and 600 or less.) The number average molecular weight is 250 or more and 100,000 or less, At least one metal (M1) selected from the group consisting of metals of Groups 6, 7, 8, 9, 10, and 11 of the long form periodic table is contained in a total amount of 1 ppm to 25 ppm in the polycarbonate diol, and at least one metal (M2) selected from the group consisting of metals in Group 1 of the long form periodic table is contained in the polycarbonate diol in a total amount of 0.5 ppm or more and 12.5 ppm or less, The Hazen color number measured in accordance with JIS-K0071-1 (1998) is 50 or less, the amount of ether bonds is 5 mol% or less, The purity of the terminal primary hydroxyl group (OH) is 97% or more. Polycarbonate diol.

11. The polycarbonate diol according to claim 10, wherein the polycarbonate diol is a polycondensate obtained by a transesterification reaction between a dihydroxy compound and a carbonate ester.

12. The polycarbonate diol according to claim 10 or 11, wherein the metal (M1) is at least one metal selected from the group consisting of molybdenum, manganese, iron, cobalt, nickel, and copper, and the metal (M2) is at least one metal selected from the group consisting of lithium, sodium, and potassium.

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

14. A polyurethane comprising the polycarbonate diol according to claim 10 or 11.

15. The present invention comprises at least two transesterification catalysts, namely, a transesterification catalyst A1 containing at least one metal (M1) selected from the group consisting of metals in Groups 6, 7, 8, 9, 10, and 11 of the long-form periodic table, and a transesterification catalyst A2 containing at least one metal (M2) selected from the group consisting of metals in Group 1 of the long-form periodic table; The transesterification catalyst A1 is at least one metal complex and / or a hydrate thereof represented by the following formula (1): The transesterification catalyst A2 is an alcoholate of at least one alcohol and at least one metal (M2) selected from the group consisting of metals of Group 1 of the long form periodic table, represented by the following formula (3): 【Transformation 5】 (In the formula, R 1 and R 3 each independently represent a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon groups of R 1 and R 3 may be substituted with a halogen atom or may have an oxygen atom; R 2 represents hydrogen or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group of R 2 may be substituted with a halogen atom or may have an oxygen atom; 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 form periodic table; and n is 1, 2, or 3. The metal complex represented by formula (1) may also be an association of multiple metals.) 【Transformation 7】 (wherein R 5 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R 5 may be substituted with a halogen atom or may have an oxygen atom.)

16. A method for producing a catalyst ... the transesterification catalyst A1 is a salt of at least one carboxylic acid 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 form periodic table, and / or a hydrate thereof, represented by the following formula (2): The transesterification catalyst A2 is an alcoholate of at least one alcohol and at least one metal (M2) selected from the group consisting of metals of Group 1 of the long form periodic table, represented by the following formula (3): 【Transformation 6】 (In the formula, R 4 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R 4 may be substituted with a halogen atom or may have an oxygen atom.) 【Transformation 7】 (wherein R 5 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group of R 5 may be substituted with a halogen atom or may have an oxygen atom.)

17. The transesterification catalyst according to claim 15 or 16, wherein the metal (M1) is at least one metal selected from the group consisting of molybdenum, manganese, iron, cobalt, nickel, and copper.

18. 17. The transesterification catalyst according to claim 15 or 16, wherein the metal (M1) is manganese.

19. The transesterification catalyst according to claim 15 or 16, wherein the metal (M2) is at least one metal selected from the group consisting of lithium, sodium, and potassium.

20. 17. The transesterification catalyst according to claim 15 or 16, wherein the metal (M2) is lithium.

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