JP2023126332A - Polycarbonate polyol and production method thereof - Google Patents

Abstract

To provide a polycarbonate polyol that is liquid at normal temperature, is reduced in color number and turbidity and has an average number of hydroxyl functional groups of more than 2 and to provide a production method of the polycarbonate polyol.SOLUTION: The polycarbonate polyol which is liquid at normal temperature, is reduced in color number and turbidity and has an average number of hydroxyl functional groups of more than 2 can be produced by allowing the reaction of (A) a polycarbonate polyol and (B) a polyol containing (b1) a polyester polyol having the number of hydroxyl functional groups of 3 or more to proceed using a specific catalyst under appropriate reaction conditions and then adding an additive.SELECTED DRAWING: None

Description

The present invention relates to a polycarbonate polyol and a method for producing the same.

Like polyester polyols and polyether polyols, polycarbonate polyols are useful as raw materials for producing polyurethane resins, adhesives, paints, and the like by reacting with polyisocyanate compounds. Since polyester polyols have ester bonds, polyurethane resins obtained from them have the disadvantage of poor hydrolysis resistance, and polyether polyols have ether bonds, so they have the disadvantage of poor weather resistance and heat resistance. On the other hand, polycarbonate polyols yield polyurethane resins with excellent durability such as heat resistance, weather resistance, hydrolysis resistance, and chemical resistance.

Such polycarbonate polyols are usually produced by transesterifying a carbonate ester and a diol in the presence of a catalyst.

Furthermore, in order to improve the mechanical strength and durability of polyurethane resins, polycarbonate polyols obtained by transesterifying aryl carbonates, primary aliphatic triols such as trimethylolpropane, and aliphatic or alicyclic diols have been developed. It has been proposed (Patent Document 1). Furthermore, polycarbonate polyols obtained by transesterification of polycarbonate diol and triol compounds and/or tetraol compounds have also been proposed (Patent Documents 2 and 3).

However, transesterification reactions with triols and tetraols tend to be difficult to proceed even when the disclosed catalysts are added. Furthermore, depending on the catalyst species, there may be cases where coloring or turbidity becomes large, and there is a risk that satisfactory physical properties may not be obtained when used as a paint.

Special Publication No. 57-39650 Japanese Patent Application Publication No. 3-220233 Japanese Patent Application Publication No. 2012-184380

The present invention has been made in view of the above-mentioned background art, and provides a polycarbonate polyol that is liquid at room temperature, has reduced color number and turbidity, and has an average number of hydroxyl functional groups exceeding 2, and a method for producing the same. The task is to do so.

As a result of intensive studies to solve the above problems, the present inventors found that by using a specific inorganic metal compound or an organic metal compound, the average number of hydroxyl functional groups is liquid at room temperature and has a reduced number of colors and turbidity. It has been discovered that a polycarbonate polyol having a polycarbonate polyol of more than 2 can be obtained, and the present invention has been completed.

That is, the present invention includes the embodiments shown below.

[1] A polycarbonate diol (A), a polyol (B) containing a polyester polyol (b1) having 3 or more hydroxyl functional groups (hereinafter also simply referred to as polyol (B)), and a metal of Group 1 of the periodic table. , an inorganic metal compound or an organic metal compound (C) containing at least one metal selected from the group consisting of metals of Group 2 of the periodic table, and a turbidity reducing additive (D), with an average number of hydroxyl functional groups. A polycarbonate polyol, characterized in that the polycarbonate polyol is more than 2.

[2] The above-mentioned [2] characterized in that the polyol (B) contains a polyester polyol (b1) having a hydroxyl functional group number of 3 or more and a polyester polyol (b2) having a hydroxyl functional group number of 2 or more and less than 3. 1].

[3] The turbidity reducing additive (D) contains at least one selected from the group consisting of inorganic acids, organic acids, esters of organic acids, and acyl halides; The polycarbonate polyol described in [2].

[4] A method for producing a polycarbonate polyol according to any one of [1] to [3] above, wherein the polycarbonate diol (A) and the polyol (B) are a metal of Group 1 of the periodic table, and a metal of Group 1 of the periodic table. A transesterification reaction is carried out in the presence of an inorganic metal compound or an organometallic compound (C) containing at least one selected from the group consisting of Group 2 metals, and after completion of the exchange reaction, a turbidity reducing additive (D) is added. A method for producing a polycarbonate polyol, characterized by:

[5] A polyurethane resin obtained from the polycarbonate polyol according to any one of [1] to [3] above and a polyisocyanate.

[6] A coating composition containing the polyurethane resin described in [5] above.

[7] An adhesive composition containing the polyurethane resin according to [5] above.

Note that normal temperature in the present invention refers to a temperature range of 5°C or higher and 35°C or lower. Furthermore, the term "liquid" in the present invention refers to a state that has even a slight fluidity at room temperature.

According to the present invention, it is possible to obtain a polycarbonate polyol that is liquid at room temperature, has reduced color number and turbidity, and has an average number of hydroxyl functional groups exceeding 2.

The present invention will be explained in detail below. The polycarbonate polyol of the present invention comprises a polycarbonate diol (A), a polyol (B) containing a polyester polyol (b1) having a functional number of hydroxyl groups of 3 or more, a metal of group 1 of the periodic table, and a metal of group 2 of the periodic table. It is obtained from an inorganic metal compound or an organic metal compound (C) (hereinafter also simply referred to as component (C)) containing at least one selected from the group consisting of metals, and a turbidity reducing additive (D), and has an average hydroxyl group functionality. It is a polycarbonate polyol having more than two bases.

Examples of the polycarbonate diol (A) in the present invention include dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, alkylene carbonates such as ethylene carbonate and propylene carbonate, diphenyl carbonate, dinaphthyl carbonate, dianthryl carbonate, and diphenanthryl carbonate. , diindanyl carbonate, tetrahydronaphthyl carbonate, and other diaryl carbonates, and glycols.

Examples of the glycol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, Diols include cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, ethylene oxide and propylene oxide adducts of bisphenol A, bis(β-hydroxyethyl)benzene, xylylene glycol, etc. be able to. These may be used alone or in combination of two or more.

Examples of the polyester polyol (b1) having a hydroxyl functional group of 3 or more of the present invention include a polyester polyol obtained from a polyol containing a polyhydric alcohol having a hydroxyl functional group of 3 or more and a dicarboxylic acid, or a polyester polyol having a hydroxyl functional group of 3 or more. Examples include polyols obtained by ring-opening addition polymerization of cyclic ester compounds such as lactones using a polyhydric alcohol as an initiator.

Examples of the polyhydric alcohol having three or more hydroxyl functional groups include trimethylolpropane, glycerin, pentaerythritol, and sorbitol. Note that difunctional alcohols such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, neopentyl glycol, hexamethylene glycol, dipropylene glycol, and trimethylene glycol may be used in combination as long as the performance is not deteriorated.

Examples of dicarboxylic acids include polybasic acids such as oxalic acid, malonic acid, maleic acid, adipic acid, tartaric acid, pimelic acid, sebacic acid, phthalic acid, and terephthalic acid, and one or two selected from these. More than one species can be used together.

Preferred lactones include, for example, β-propiolactone, β-butyrolactone, γ-butyrolactone, β-valerolactone, γ-valerolactone, δ-valerolactone, α-caprolactone, β-caprolactone, γ-caprolactone, δ- These include caprolactone, ε-caprolactone, α-methyl-ε-caprolactone, β-methyl-ε-caprolactone, 4-methylcaprolactone, γ-caprylolactone, ε-capryrolactone, and ε-palmitolactone. One type or a mixture of two or more types selected from these can be used. Among these, ring-opening addition polymers of ε-caprolactone using trimethylolpropane as an initiator are preferred from the standpoint of stability and economy during polymerization.

Further, in the present invention, as a component of the polyol (B), in addition to the polyester polyol (b1) having a hydroxyl functional group number of 3 or more, a polyester polyol (b2) having a hydroxyl functional group number of 2 or more and less than 3 may be used in combination. can. Particularly preferred are polyester polyols obtained from glycol and dicarboxylic acid, and polyols obtained by ring-opening addition polymerization of cyclic ester compounds such as lactones using glycol as an initiator.

Examples of the glycol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol. , 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol , cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, ethylene oxide and propylene oxide adducts of bisphenol A, bis(β-hydroxyethyl)benzene, xylylene glycol, etc. Trimethylolpropane, glycerin, pentaerythritol, sorbitol, etc. can be used in combination.

Examples of dicarboxylic acids include polybasic acids such as oxalic acid, malonic acid, maleic acid, adipic acid, tartaric acid, pimelic acid, sebacic acid, phthalic acid, and terephthalic acid, and one type selected from these acids. Or two or more types can be used together.

Further, preferable lactones include, for example, β-propiolactone, β-butyrolactone, γ-butyrolactone, β-valerolactone, γ-valerolactone, δ-valerolactone, α-caprolactone, β-caprolactone, γ-caprolactone, Examples include δ-caprolactone, ε-caprolactone, α-methyl-ε-caprolactone, β-methyl-ε-caprolactone, 4-methylcaprolactone, γ-caprylolactone, ε-capryrolactone, and ε-palmitolactone. , one kind or two or more kinds selected from these can be used in combination. Among these, ring-opening addition polymers of ε-caprolactone using ethylene glycol as an initiator are preferred from the standpoint of stability and economic efficiency during polymerization.

The mass ratio of polycarbonate diol (A) and polyester polyol (b1) having a hydroxyl functional group number of 3 or more is in the range of (A)/(b1) = 75/25 to 55/45, and (A)/(b1) = preferably in the range of 70/30 to 60/40. In addition, when a polyester polyol (b2) having a hydroxyl functional group number of 2 or more and less than 3 is used together, the mass ratio is preferably in the range of (A)/(b1+b2)=75/25 to 55/45; More preferably, (b1+b2)=70/30 to 60/40.

The average number of hydroxyl functional groups in the polycarbonate polyol of the present invention is more than 2, preferably from 2.3 to 3.5, more preferably from 2.5 to 3.0.

Further, the average hydroxyl value of the polycarbonate polyol is 75 to 285 mgKOH/g, preferably 90 to 180 mgKOH/g.

In addition, the average number of hydroxyl functional groups in the present invention was calculated as follows based on the nominal number of functional groups.
Average number of hydroxyl functional groups = ((Polycarbonate diol (A) number of functional groups x mol) + (Polyester polyol (b1) number of functional groups x mol) + (Polyester polyol (b2) number of functional groups x mol)) / ((Polycarbonate diol (A) mol) + (polyester polyol (b1) mol) + (polyester polyol (b2) mol))

In the present invention, the number average molecular weight of the polycarbonate polyol is preferably 400 to 5,000, more preferably 500 to 2,000, considering ease of synthesis and handling. Note that the number average molecular weight can be determined by GPC (gel permeation chromatography) measurement using standard polystyrene as a calibration curve.

In the present invention, an inorganic metal compound or an organometallic compound (C) containing at least one selected from the group consisting of a metal in Group 1 of the periodic table and a metal in Group 2 of the periodic table is used. This component (C) has the effect of promoting transesterification. Examples of metals in Group 1 of the periodic table include lithium, sodium, potassium, rubidium, and cesium, and examples of metals in Group 2 of the periodic table include magnesium, calcium, strontium, barium, and the like. In the present invention, inorganic metal compounds or organic metal compounds of these metals may be mentioned, and one type or two or more types selected from these can be used in combination. Among these, inorganic metal compounds of metals in Group 1 of the periodic table are preferred, and lithium acetate, potassium carbonate, and potassium hydrogen carbonate are particularly preferred in view of ease of proceeding with the transesterification reaction and ease of handling.

The amount of component (C) to be used is 0.0001 to 1% by mass, preferably 0.0001 to 1% by mass of the total mass of polycarbonate diol (A) and polyol (B) containing polyester polyol (b1) having 3 or more hydroxyl functional groups. It is .001 to 0.1% by mass. When the amount of component (C) is less than the lower limit, the reaction time becomes longer and the resulting polycarbonate polyol becomes more likely to be colored. Moreover, when the upper limit is exceeded, turbidity tends to increase.

The reaction temperature for the transesterification reaction is preferably 70 to 250°C, more preferably 80 to 220°C.

A polycarbonate polyol in which the transesterification reaction has not sufficiently progressed is derived from unreacted highly crystalline raw materials and has a solid state at room temperature.

Examples of the turbidity reducing additive (D) of the present invention include inorganic acids such as phosphoric acid and hydrochloric acid, organic acids having sulfonic acid groups, sulfamic acid groups, etc., esters thereof, acyl halides, etc. One type or two or more types selected from these can be used in combination. In particular, phosphorus compounds such as phosphoric acid, phosphoric esters, phosphorous acid, and phosphorous esters are preferred from the viewpoint of ease of handling. Note that the addition timing is preferably 140° C. or lower after the end of the transesterification reaction.

The amount of the turbidity reducing additive (D) added is 0.0001 to 1% by mass, preferably 0.001 to 0.1% by mass of the total mass of polycarbonate diol (A) and polyol (B). . When the amount added is less than the lower limit, the turbidity and color number of the resulting polycarbonate polyol tend to increase, and when it exceeds the upper limit, the reactivity of the polycarbonate polyol may be delayed.

A polyurethane resin can be obtained by reacting the polycarbonate polyol of the present invention described above with a polyisocyanate by a known method.

The polyisocyanate is not particularly limited, and can be appropriately selected from various conventionally known polyisocyanates. For example, aliphatic isocyanates such as hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 2-methylpentane-1,5-diisocyanate, lysine diisocyanate; isophorone diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene Alicyclic diisocyanates such as diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated tetramethylxylene diisocyanate; 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4' -diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3 '-Dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3 Aromatic isocyanates such as '-dimethoxydiphenyl-4,4'-diisocyanate; aromatic aliphatic diisocyanates such as xylylene-1,4-diisocyanate and xylylene-1,3-diisocyanate, etc. can be used. In addition, urethane-modified polyisocyanates, urea-modified polyisocyanates, allophanate-modified polyisocyanates, burette-modified polyisocyanates, carbodiimide-modified polyisocyanates, and uretonimines can be produced by conventionally known methods using these organic polyisocyanates and alcohol, etc., if necessary. Modified polyisocyanates, uretdione-modified polyisocyanates, and isocyanurate-modified polyisocyanates may be used alone or in combination of two or more.

The polyurethane resin thus obtained can be suitably used in coating compositions, adhesive compositions, and the like.

Examples of the present invention will be described below, but the present invention is not limited to these Examples. Note that % and parts in the examples are based on mass unless otherwise specified.

[Production of polycarbonate diol 1]
A reaction apparatus comprising a stirrer, a thermometer, a heating device, and a distillation column was prepared with a molar ratio of 1,6-hexanediol (hereinafter abbreviated as 1,6-HG) and diethyl carbonate (hereinafter abbreviated as DEC) of 1. 830 g of 1,6-HG and 771 g of DEC were charged so that the ratio of The temperature was increased to 190°C. When the distillation of ethanol became slow and the temperature at the top of the distillation column fell below 50°C, the pressure was gradually reduced to 1.3 kPa while the reaction temperature remained at 190°C, and the reaction was continued at a pressure of 1.3 kPa for another 7 hours. Made it react. Further, the reaction was continued at a reaction temperature of 190° C. under a reduced pressure of 1.3 kPa or less until the hydroxyl value of the reactant reached 54 to 58 (mgKOH/g) to obtain polycarbonate diol (Polyol-1). The average number of hydroxyl functional groups of Polyol-1 was 2.0, and the hydroxyl value was 55.6 (mgKOH/g).

[Production of polycarbonate diol 2]
Production of polycarbonate diol was performed using the same equipment as in 1, except that 826 g of 1,6-HG and 787 g of DEC were charged so that the molar ratio of 1,6-HG and DEC was 1.05:1. Synthesis was performed in the same manner as in Production 1 to obtain polycarbonate diol (Polyol-2). The average number of hydroxyl functional groups of the obtained Polyol-2 was 2.0, and the hydroxyl value was 37.2 (mgKOH/g).

(Example 1: Production of polycarbonate polyol 1)
A reaction apparatus equipped with a stirrer, a thermometer, and a heating device was charged with 600 g of Polyol-1 obtained in polycarbonate diol production 1, 400 g of polycaprolactone triol (Plaxel 303), and 0.1 g of lithium acetate, and heated at 190°C. The transesterification reaction was carried out for 5 hours. Thereafter, the mixture was cooled to 120° C., 0.5 of JP-508 (manufactured by Johoku Kagaku Co., Ltd.) was added, and the mixture was stirred and mixed for 30 minutes to obtain polycarbonate polyol (PCP-1). The average number of hydroxyl functional groups of the obtained PCP-1 was 2.81, and the hydroxyl value was 250.4 (mgKOH/g).

(Example 2: Production of polycarbonate polyol 2)
A reaction apparatus equipped with a stirrer, a thermometer, and a heating device was charged with 500 g of Polyol-2 obtained in polycarbonate diol production 2, 500 g of polycaprolactone triol (Plaxel 305), and 0.1 g of potassium carbonate, and heated at 190°C. The transesterification reaction was carried out for 5 hours. Thereafter, the mixture was cooled to 120° C., 0.5 g of JP-508 was added, and the mixture was stirred and mixed for 30 minutes to obtain polycarbonate polyol (PCP-2). The average number of hydroxyl functional groups of the obtained PCP-2 was 2.85, and the hydroxyl value was 171.7 (mgKOH/g).

(Example 3: Production of polycarbonate polyol 3)
Into a reaction apparatus equipped with a stirrer, a thermometer, and a heating device, 550 g of Polyol-2 obtained in polycarbonate diol production 2, 400 g of polycaprolactone triol (Plaxel 305), and 50 g of polycaprolactone diol (Plaxel 210) were charged. 0.1 g of potassium hydrogen carbonate was charged, and the transesterification reaction was carried out at 190°C for 5 hours. Thereafter, the mixture was cooled to 120° C., 0.5 g of JP-508 was added, and the mixture was stirred and mixed for 30 minutes to obtain polycarbonate polyol (PCP-3). The average number of hydroxyl functional groups of the obtained PCP-3 was 2.76, and the hydroxyl value was 148.6 (mgKOH/g).

(Example 4: Production of polycarbonate polyol 4)
Into a reaction apparatus equipped with a stirrer, a thermometer, and a heating device, 600 g of Polyol-2 obtained in polycarbonate diol production 2, 400 g of polycaprolactone tetraol (Plaxel 410), and 0.1 g of potassium hydrogen carbonate were charged. The transesterification reaction was carried out at °C for 5 hours. Thereafter, the mixture was cooled to 120° C., 0.5 g of JP-508 was added, and the mixture was stirred and mixed for 30 minutes to obtain polycarbonate polyol (PCP-4). The average number of hydroxyl functional groups of the obtained PCP-4 was 3.32, and the hydroxyl value was 108.6 (mgKOH/g).

(Example 5: Production of polycarbonate polyol 5)
A reaction apparatus equipped with a stirrer, a thermometer, and a heating device was charged with 600 g of Polyol-2 obtained in polycarbonate diol production 2, 400 g of polycaprolactone triol (Plaxel 305), and 0.1 g of barium acetate, and heated at 190°C. The transesterification reaction was carried out for 5 hours. Thereafter, the mixture was cooled to 120° C., 0.5 g of JP-508 was added, and the mixture was stirred and mixed for 30 minutes to obtain polycarbonate polyol (PCP-5). The average number of hydroxyl functional groups of the obtained PCP-5 was 2.78, and the hydroxyl value was 144.9 (mgKOH/g).

(Comparative Example 1: Production of polycarbonate polyol 6)
A reaction apparatus equipped with a stirrer, a thermometer, and a heating device was charged with 500 g of Polyol-2 obtained in polycarbonate diol production 2 and 500 g of polycaprolactone triol (Plaxel 305), and a transesterification reaction was performed at 190 ° C. for 5 hours. Ta. Thereafter, the mixture was cooled to 120° C., 0.5 g of JP-508 was added, and the mixture was stirred and mixed for 30 minutes to obtain polycarbonate polyol (PCP-6). The average number of hydroxyl functional groups of the obtained PCP-6 was 2.85, and the hydroxyl value was 171.5 (mgKOH/g).

(Comparative Example 2: Production of polycarbonate polyol 7)
A reaction apparatus equipped with a stirrer, a thermometer, and a heating device was charged with 500 g of Polyol-2 obtained in polycarbonate diol production 2, 500 g of polycaprolactone triol (Plaxel 305), and 0.1 g of tetrabutoxytitanium, and heated at 190°C. The transesterification reaction was carried out for 5 hours. Thereafter, the mixture was cooled to 120° C., 0.5 g of JP-508 was added, and the mixture was stirred and mixed for 30 minutes to obtain polycarbonate polyol (PCP-7). The average number of hydroxyl functional groups of the obtained PCP-7 was 2.85, and the hydroxyl value was 171.6 (mgKOH/g).

(Comparative Example 3: Production of polycarbonate polyol 8)
Into a reaction apparatus equipped with a stirrer, a thermometer, and a heating device, 500 g of Polyol-2 obtained in polyol production 2, 500 g of polycaprolactone triol (Plaxel 305), and 0.1 g of lithium acetate were charged, and esterification was carried out at 190°C. The exchange reaction was carried out for 5 hours to obtain polycarbonate polyol (PCP-8). The average number of hydroxyl functional groups of the obtained PCP-8 was 2.85, and the hydroxyl value was 171.7 (mg-KOH/g).

The raw materials used are shown below.
・Plaxel 303 Polycaprolactone triol (molecular weight = 310, hydroxyl value = 542, number of functional groups = 3) Manufactured by Daicel (product name)
・Plaxel 305 Polycaprolactone triol (molecular weight = 550, hydroxyl value = 305, number of functional groups = 3) Manufactured by Daicel (product name)
・Plaxel 410 polycaprolactone tetraol (molecular weight = 1000, hydroxyl value = 216, number of functional groups = 4) Manufactured by Daicel (product name)
・Plaxel 210 Polycaprolactone diol (molecular weight = 1000, hydroxyl value = 112, number of functional groups = 2) Manufactured by Daicel (product name)
・JP-508 Acidic phosphate ester Manufactured by Johoku Kagaku Co., Ltd. (product name).

The properties of the obtained polycarbonate polyol were confirmed. The results are shown in Table 1.
[Properties at room temperature]
The obtained polycarbonate polyol was kept at each temperature of 25°C and 5°C for 24 hours.

I held it. Those that were liquid at each temperature were designated as "A," and those that were solid were designated as "C." If the rating is A, it can be said to be good.

[Number of colors]
The color number of the obtained polycarbonate polyol is measured based on JIS-K1557, and if the color number is 60 or less, it is said to be good.

[Turbidity]
The turbidity of the obtained polycarbonate polyol is measured by measuring kaolin turbidity (visual method) based on JIS-K0101, and if the turbidity is 2 or less, it is considered to be good.

Claims (7)

Polycarbonate diol (A), polyol (B) containing a polyester polyol (b1) having a hydroxyl functional group number of 3 or more, a metal of Group 1 of the periodic table, and a metal of Group 2 of the periodic table. A polycarbonate polyol obtained from an inorganic metal compound or an organometallic compound (C) containing at least one type and a turbidity reducing additive (D), and characterized in that the average number of hydroxyl functional groups exceeds 2. According to claim 1, the polyol (B) comprises a polyester polyol (b1) having a hydroxyl functional group number of 3 or more and a polyester polyol (b2) having a hydroxyl functional group number of 2 or more and less than 3. polycarbonate polyol. The polycarbonate according to claim 1 or 2, wherein the turbidity reducing additive (D) contains at least one selected from the group consisting of inorganic acids, organic acids, esters of organic acids, and acyl halides. Polyol. A method for producing a polycarbonate polyol according to any one of claims 1 to 3, comprising:
The polycarbonate diol (A) and the polyol (B) are combined into an inorganic metal compound or an organometallic compound (C) containing at least one selected from the group consisting of metals in group 1 of the periodic table and metals in group 2 of the periodic table. A method for producing a polycarbonate polyol, which comprises carrying out a transesterification reaction in the presence of a polycarbonate polyol, and adding a turbidity reducing additive (D) after the completion of the exchange reaction. A polyurethane resin obtained from the polycarbonate polyol according to any one of claims 1 to 3 and a polyisocyanate. A coating composition comprising the polyurethane resin according to claim 5. An adhesive composition comprising the polyurethane resin according to claim 5.