JP3508569B2 - Method for producing polycarbonate polyol - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polycarbonate polyol used as a raw material for polyurethane used in various fields such as synthetic leather, elastomers and coatings. More specifically, the present invention relates to a method for producing a polycarbonate polyol which is less colored and has less side reaction by transesterification of a diaryl carbonate and an aliphatic polyhydroxy compound.

[0002]

2. Description of the Related Art As a method for producing a polycarbonate polyol by transesterification of a diaryl carbonate and a polyhydroxy compound, a method for producing a polycarbonate polyol without a catalyst (Japanese Patent Publication No. 45-955).
No. 3, Japanese Patent Publication No. 46-4693, etc.), or alkali metal, alkaline earth metal, alkoxide of alkali metal or alkaline earth metal, titanium trichloride, titanium tetrachloride, tetraethyl titanate, tetra-iso.
-Propyl titanate, tetra-n-butyl titanate, etc. A method for producing a polycarbonate polyol using a basic compound or an organometallic compound as a catalyst (JP-A-61-15).
No. 1235, JP-A-62-187725, JP-A-64-118, JP-A-2-49025 and JP-A-2-175721) are known. However, in these production methods, there is a problem that the coloring of the polycarbonate polyol produced from the diaryl carbonate such as diphenyl carbonate is larger than that when the dialkyl carbonate such as dimethyl carbonate or diethyl carbonate is used as the raw material.

On the other hand, in a method for producing a polycarbonate polyol prepared from an aliphatic carbonate compound, for example, a dialkyl carbonate such as dimethyl carbonate or diethyl carbonate as a raw material, it is reported that a transesterification catalyst is used because the transesterification rate is slow. (JP-A-51-83693 and JP-A-51-836)
94, JP 61-151263 A, JP 2-A.
284918, JP-A-2-284919, etc.).

For example, when a basic alkali metal salt or alkaline earth metal salt is used as a transesterification catalyst in the above-mentioned method for producing a polycarbonate polyol, the reaction rate is increased, but a side reaction occurs to cause hydroxyl groups at both ends. The above-mentioned polycarbonate polyol cannot be produced, and when a polyurethane is produced from this polycarbonate polyol, an abnormal reaction occurs with isocyanate and the urethane-forming reaction cannot be controlled. Further, when an organometallic compound such as titanium or tin alkoxide is used as the transesterification catalyst, it is possible to produce a polycarbonate polyol in which side reactions are suppressed and coloring is reduced. However, when a polyurethane is produced using this polycarbonate polyol, it becomes difficult to control the urethane-forming reaction with an isocyanate compound due to the influence of the remaining catalyst, or gelation occurs during the reaction, so that the catalyst of Inactivation treatment (see Japanese Patent Laid-Open No. 64-1724, etc.) must be performed, which is not industrially economical. Also, when adding Bronsted acid or acidic alkali metal salts or alkaline earth metal salts, these additives have no catalytic action,
The transesterification reaction between the aliphatic carbonate compound and the polyhydroxy compound does not proceed.

Further, in Japanese Patent Laid-Open No. 64-1726, a diaryl carbonate purified by adsorption treatment with an inorganic adsorbent such as activated clay, acid clay, diatomaceous earth and the like is used as an ester with a polyhydroxy compound. A method for producing a high-quality polycarbonate polyol with little coloration by an exchange reaction, and JP-A-60-181125 discloses an epoxy group-containing compound having one or more epoxy groups in a molecule. Organic titanium compounds, by performing transesterification of a diaryl carbonate and a polyhydroxy compound in the presence of a titanium compound such as an inorganic titanium compound, a method of producing a high-quality polycarbonate polyol with little coloring,
Each is disclosed.

[0006]

However, the above-mentioned JP-A Nos. 64-1726 and 60-1811.
The methods described in Japanese Patent No. 25 are all directed to cases in which, for example, diphenyl carbonate obtained by reacting phenol with phosgene is used as the raw material diaryl carbonate. Therefore, in order to prevent the side reaction and / or the coloring of the polycarbonate polyol, the method described in JP-A No. 64-1726 requires a purification step of adsorbing and removing a minute amount of the halogen component in the raw material diaryl carbonate in advance. In the method described in JP-A-60-181125, hydrogen halide which is originally present in the starting diaryl carbonate or which is generated during the transesterification reaction is reacted with the epoxy group-containing compound. It is necessary to discharge the hydroxyl group-terminated compound generated from the system out of the system, which complicates the process and is not economical as a method for producing a polycarbonate polyol. Incidentally, in JP-A-60-181125, dialkyl carbonate compounds and the like used in the production of polycarbonate are usually required to be purified by a high degree of washing or distillation, but in this method, washing with an ordinary alkaline aqueous solution is required. Since a dicarbonate compound of the quality obtained by distillation or distillation can be used sufficiently,
Although there is a description that a high degree of purification of the raw material is not required, there is no description about the purification treatment of the polyhydroxy compound which is the other raw material for producing the polycarbonate polyol. It is an object of the present invention to provide a method for producing a polycarbonate polyol which is free from coloration and has a small number of side reactions, from a diaryl carbonate and an aliphatic polyhydroxy compound.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that when a polycarbonate polyol is produced from a diaryl carbonate and an aliphatic polyhydroxy compound by a transesterification reaction, By using an aliphatic polyhydroxy compound that has been subjected to a hydrogenation (hereinafter referred to as "hydrogenation") purification treatment in advance, it was found that a polycarbonate polyol having no coloration and less side reaction can be obtained.
The present invention has been completed.

That is, the first aspect of the present invention is a method for producing a polycarbonate polyol by transesterification of a diaryl carbonate and an aliphatic polyhydroxy compound, wherein the aliphatic polyhydroxy compound is hydrogenated and purified. This can be achieved by providing a method for producing a polycarbonate polyol characterized by using an aliphatic polyhydroxy compound. The second invention described in claim 2 can be achieved by providing a method for producing a polycarbonate polyol according to the first invention, wherein the aliphatic polyhydroxy compound is 1,6-hexanediol. In the third aspect of the present invention, the hydrogenation refining treatment is carried out in the presence of a noble metal catalyst at 50 to 2
This can be achieved by providing the method for producing a polycarbonate polyol according to the first or second invention, which is carried out at a temperature of 00 ° C. and a pressure of atmospheric pressure to 50 atmospheres.

Furthermore, the fourth invention according to claim 4 is any one of the above-mentioned first to third inventions, wherein the molar ratio of the aliphatic polyhydroxy compound to the diaryl carbonate is 1.01 to 3.00. This can be achieved by providing a method for producing a polycarbonate polyol according to one.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention will be described in detail below. The aryl group of the diaryl carbonate used in the present invention may have various substituents, and the aryl groups may be the same or different. Specific examples of such an aryl group include a phenyl group, a tolyl group, a xylyl group, a biphenylyl group, a naphthyl group, an anthryl group, a phenanthryl group, a chlorophenyl group and a nitrophenyl group. Diphenyl carbonate is particularly preferred as the carbonate.

Aliphatic polyhydroxy compounds suitable for use in the present invention include 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, 2
-Methyl-1,3-propanediol, neopentyl glycol, 2-ethyl-1,3-propanediol, 3
-Methyl-1,5-pentanediol, 2-ethyl-
1,6-hexanediol, 2,2,4-trimethyl-
Aliphatic diols such as 1,6-hexanediol, 2-methyl-1,8-octanediol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, polytetramethylene glycol, 1,3-cyclohexane Diol, 1,4-cyclohexanediol,
1,4-dimethylolcyclohexane, 2,2′-bis- (4-hydroxycyclohexyl) -propane, 2,
Cycloaliphatic diols such as 2,4,4-tetramethylcyclobutane-1,3-diol, aliphatic triols such as glycerin, trimethylolethane, trimethylolpropane and hexanetriol, and pentaerythritol, dipentaerythritol, diglycerin , Sorbitol, and other aliphatic polyols. These aliphatic polyhydroxy compounds can be used alone or as a mixture of two or more kinds.

In the method of the present invention, in order to produce a polycarbonate polyol by transesterification of the diaryl carbonate and the aliphatic polyhydroxy compound, it is necessary to previously subject the aliphatic polyhydroxy compound to hydrogenation purification treatment. The hydrogenation purification treatment of the above aliphatic polyhydroxy compound is preferably performed in the presence of a catalyst. As a catalyst used for hydrogenation purification,
Pd, Pt, Ru, Re, Rh, Os, Ir, Ni, P
tO ₂ , RuO, CuO, Cu ₂ O, Cr ₂ O ₃ , Fe
A noble metal catalyst such as ₂ O ₃ may be used, and these may be used alone or in combination of two or more.
Further, in order to increase the surface area of the catalyst, activated carbon, aluminum oxide, titania (TiO ₂ ), zirconia (Zr
The precious metal catalyst may be supported on a carrier such as O ₂ ), zeolite, silica (SiO ₂ ), silica-alumina, and magnesia (MgO).

When the batch reaction is carried out, the amount of the noble metal catalyst used is 0.1 to 10000 ppm, preferably 1 to 1000 ppm by weight based on the aliphatic polyhydroxy compound as a metal element. When the amount of the catalyst used is less than 0.1 ppm, the hydrogenation purification treatment of the aliphatic polyhydroxy compound becomes insufficient, and the polycarbonate polyol obtained by the transesterification reaction of the aliphatic polyhydroxy compound and the diaryl carbonate is colored. I have something to do. On the other hand, when the amount of the catalyst used is more than 10,000 ppm, there is no advantage in the hydrogenation purification treatment of the aliphatic polyhydroxy compound such as the decomposition of the aliphatic polyhydroxy compound, which is not economical.

The reaction temperature is 50 to 200.degree. C., preferably 80 to 160.degree. C., which is the condition for the hydrogenation purification treatment of the aliphatic polyhydroxy compound. 50 ° C
At lower temperatures, the hydrorefining process is time-consuming and not industrially suitable. Further, at a temperature exceeding 200 ° C., the aliphatic polyhydroxy compound is decomposed, which is not economical. The pressure of hydrogen supplied is not particularly limited, but is preferably normal pressure to 50 atm. Under reduced pressure, the progress of the hydrogenation reaction is slowed down, and there are problems that not only the hydrogenation purification treatment of the aliphatic polyhydroxy compound takes too long, but also a reduced pressure facility is required. Meanwhile, 5
Even if the pressure exceeds 0 atm, the reactor is required to have a special pressure resistance performance, which is not industrially economical. Further, the reaction system of the hydrogenation purification treatment of the aliphatic polyhydroxy compound in the method of the present invention may be either a batch system or a continuous system. The reactor is not particularly limited,
For example, in the case of batch method, in the autoclave,
In the case of the continuous system, the hydrogenation reaction may be carried out in a fixed bed column or the like. As the aliphatic polyhydroxy compound hydrotreated and refined as described above, the filtered noble metal catalyst can be used as it is, but further purification treatment such as washing and distillation does not prevent the use.

When a polycarbonate polyol is produced by the method of the present invention, the proportion of the aliphatic polyhydroxy compound charged is preferably 1.01 to 3.00 in terms of molar ratio to the diaryl carbonate.
Wherein the molar ratio of the aliphatic polyhydroxy compound to the diaryl carbonate is 1.01 less than all molecular ends of the obtained polycarbonate polyol it does not become a hydroxyl group, C ₆ H ₅ -OCOO- remains at the molecular end. When it is more than 3.00, there is no advantage in the transesterification reaction of the diaryl carbonate and the aliphatic polyhydroxy compound, and an excessive amount of the aliphatic polyhydroxy compound has to be distilled off. , Industrially uneconomical.

The reaction temperature in producing the polycarbonate polyol of the present invention is not particularly limited,
It is desirable that the temperature is 100 to 300 ° C, preferably 150 to 250 ° C, and more preferably 150 to 220 ° C.
If the reaction temperature is high, a decarboxylation reaction or a dehydration reaction may occur as a side reaction, resulting in an ether bond in the molecule of the obtained polycarbonate polyol or a vinyl group at the molecular end. Further, when the temperature is low, the transesterification rate is slow, an extremely long reaction time is required, and the yield of the product is low, which is not economical.

The reaction pressure is not particularly limited, and it can be carried out under any of increased pressure, normal pressure and reduced pressure, and the hydroxyaryl compound derived from the diaryl carbonate used in the present invention. And the boiling point of the aliphatic polyhydroxy compound may be taken into consideration. For example, in the initial stage of the reaction, at a low temperature of 180 ° C. or lower for about 1 to 4 hours, subsequently at 150 to 250 ° C., preferably at 150 to 220 ° C. for several hours, and at the same temperature under a pressure of finally 20 mmHg or less. It can be carried out by a known method such as transesterification of the diaryl carbonate with the aliphatic polyhydroxy compound for several hours.

The reaction apparatus in the method of the present invention is not particularly limited, and a tank type reactor or a tube type reactor may be used, but the produced hydroxyaryl compound may be used. It is desirable to use a reactor equipped with a distillation column as a device capable of separating the starting materials, the diaryl carbonate and the aliphatic polyhydroxy compound.

In the transesterification reaction of the present invention, it is necessary to continuously withdraw the hydroxyaryl compound produced to the outside of the system to allow the reaction to proceed. Therefore, in order to assist the extraction of this hydroxyaryl compound out of the system, a small amount of an inert gas such as nitrogen, argon, or helium may be carried out under reduced pressure, atmospheric pressure or under pressure, or the reaction may be performed. The reaction may be performed by enclosing the inert gas under normal pressure or under pressure.

Furthermore, in the method of the present invention, a transesterification catalyst may or may not be present in the production of the polycarbonate polyol. When the transesterification reaction of the diaryl carbonate and the aliphatic polyhydroxy compound is carried out in the presence of a transesterification catalyst, a catalyst usually used in transesterification can be used for the reaction. For example, lithium, sodium, potassium,
Alkali metals such as rubidium and cesium, alkaline earth metals such as magnesium, calcium, strontium and barium, zinc, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper,
Zirconium, germanium, tin, lead, antimony,
Metals such as arsenic and cerium and alkoxides of these metals (sodium methylate, sodium
Ethylate, aluminum triisopropoxide, tetraethyl titanate, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-n-octyl titanate, titanium acetylacetone, etc.).

As examples of other suitable catalysts, inorganic acids such as titanic acid (IV), organic acids, and halides of the above-mentioned metals (titanium trichloride, titanium tetrachloride, titanium tetrafluoride, etc. are halogenated). Titanium, etc.), oxides (zinc oxide, antimony trioxide, germanium dioxide, inorganic oxides such as cerium trioxide, organic oxides such as dibutyltin oxide), hydroxides, carbonates (sodium carbonate, potassium carbonate, Alkali metal and alkaline earth metal carbonates such as magnesium carbonate, lead carbonate, etc., and other inorganic acid salts (zinc borate, lead silicate, lead arsenate, sodium chlorotitanate, ammonium chlorotitanate, fluorinated) Ammonium titanate, titanium sulfate, etc. and organic acid salts (acetic acid salts such as dibutyltin diacetate), titanyl ammonium oxalate, etc. Oxalic, octoate, laurates such as dibutyl tin dilaurate, naphthenates, etc.) is. Particularly useful and preferred catalysts are metal salts of organic acids such as magnesium, calcium, cerium, barium, zinc, tin and titanium, and tetraethyl titanate.
Tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-
Organic metal compounds such as organotitanium compounds such as n-octyl titanate and tetraphenyl titanate, and organotin compounds such as dibutyltin diacetate and dibutyltin dilaurate.

The amount of these transesterification catalysts to be used is 0.0001 to 1.0 of the total weight of the starting material, the diaryl carbonate and the aliphatic polyhydroxy compound.
0% is suitable, and 0.001 to 0.2% is preferable. When the amount of the catalyst used is less than 0.0001% of the total weight of the starting materials, the transesterification reaction between the diaryl carbonate and the aliphatic polyhydroxy compound may be delayed and the yield of the polycarbonate polyol may decrease. Further, even if it is used in an amount of more than 1.0% of the total weight of the starting material, there is no advantage in the transesterification reaction of the diaryl carbonate and the aliphatic polyhydroxy compound, and 1.0% is a necessary and sufficient amount. Is.

In the method of the present invention, by using the aliphatic polyhydroxy compound obtained by the hydrogenation purification treatment in advance as described above, it is possible to produce a high-quality polycarbonate polyol without coloring. You can The reason for this is not clear, but the hydrorefining process turns the trace amount of aldehydes and ketones contained in the aliphatic polyhydroxy compounds used as raw materials into alcohol compounds, and compounds with double bonds into saturated hydrocarbon compounds. This is probably because the side reaction due to the attack of the hydroxyaryl compound or the diaryl compound disappeared due to the conversion.

[0024]

EXAMPLES Next, the method of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples and comparative examples. In the following examples and comparative examples, various physical properties of the obtained polycarbonate polyol are
It was determined by the following method.

(1) Hydroxyl Value (OHv) In accordance with JIS K1557, a sample (polycarbonate polyol) was esterified with phthalic anhydride, and after reaction, excess phthalic anhydride was back-titrated with sodium hydroxide for measurement.

(2) Number average molecular weight (Mn) The number average molecular weight (Mn) was calculated by the following formula (I) from the hydroxyl value (OHv) obtained in the above item (1).

[0027]

[Equation 1]

(3) Melt Color (APHA) According to JIS K1557, a predetermined amount of sample (polycarbonate polyol) was put in a colorimetric tube and compared with an APHA standard solution.

(4) Content of ether group contained in molecular chain It was determined as the content ratio (%) of ether group to carbonate group by measuring NMR of a sample (polycarbonate polyol). The instrument used for NMR measurement is GSX-400 (made by JEOL Ltd.).

Example 1 1,6-Hexanediol (manufactured by Ube Industries, Ltd., hydroxyl value: 950 mg KOH / g, molecular weight: 118.2, the same applies below); 180 g and 2 wt% Pd-carbon powder; 1 0.5 g was put into an autoclave having an internal volume of 500 ml. Next, the autoclave was purged with nitrogen gas and then with hydrogen gas, and the temperature was gradually raised to 125
℃. Then, the reaction was carried out at 125 ° C. for 2 hours while adjusting the hydrogen pressure to 10 atm at this temperature. After completion of the reaction, Pd was removed from the reaction solution using a pressure filter.
-By removing the carbon powder, 137 g of hydrogenated and refined 1,6-hexanediol was obtained. As a result of analysis by gas chromatography (manufactured by Shimadzu Corporation, model: GC-14B) of 1,6-hexanediol before and after the reaction, the area percentages were 98.7% and 98.6, respectively.
%, And almost no deterioration was observed.

Then, diphenyl carbonate (manufactured by Tokyo Kasei Co., Ltd., special grade reagent, molecular weight: 214.2, the same applies below); 21.01 g (0.098 mol) and the above hydrogenated purified 1,6-hexane Diol; 17.38
g (0.147 mol) was placed in a flask having an internal volume of 50 ml equipped with a Vigreux-type fractionating tube, a thermometer and a nitrogen introducing tube. All these raw materials were charged in a nitrogen gas atmosphere. Then, the reaction liquid charged while gradually reducing the pressure in the flask was gradually heated to 180 ° C. and the pressure reduction degree was 200 t.
It was adjusted to orr and refluxed for 1 hour. Next, when the pressure reduction degree was gradually increased while maintaining the reaction temperature at 180 ° C., phenol derived from diphenyl carbonate was distilled out. When the reaction proceeded and the distillation of phenol was almost stopped, the reaction temperature was raised to 190 ° C., the degree of vacuum was further raised, and 1,6-hexanediol was extracted to complete the reaction. Decompression degree is finally 13t
It was orr. The total reaction time was 6.5 hours.

The total amount of phenol and 1,6-hexanediol withdrawn was 23.41 g, and the composition of the components was 1,6-hexanediol; 21.0% by weight, phenol; 78.5% by weight and diphenyl. Carbonate: 0.5% by weight. The yield of the obtained polycarbonate diol was 15.26 g. When the hydroxyl value of this polycarbonate diol was measured,
It was 25.4 mgKOH / g, and the number average molecular weight determined by the above formula (I) was 4410.

Further, when the structural analysis of the above polycarbonate diol was carried out using a 400 MHz NMR analyzer (manufactured by JEOL Ltd., model: GSX-400), a phenoxy group derived from a diaryl carbonate was found at the molecular end, and Further, since no vinyl group produced by the dehydration reaction of the hydroxyl group at the molecular end was confirmed, it was found that all the molecular ends of the obtained polycarbonate diol were hydroxyl groups. The ratio of ether groups contained in the molecular chain of the obtained polycarbonate diol was 0.24% with respect to the carbonate groups. Furthermore, in order to examine the degree of coloring of the above polycarbonate diol, the melt color (APHA) was measured and found to be 15. No coloring was observed. As described above, by using hydrogenated and refined 1,6-hexanediol as the raw material aliphatic polyhydroxy compound, it was possible to obtain a high-quality polycarbonate diol without coloring.

Comparative Example 1 21.42 g (0.100 mol) of diphenyl carbonate and 17.73 g (0.150 mol) of 1,6-hexanediol which had not been subjected to hydrorefining treatment were used in Example 1. The flask was placed in a flask with an internal volume of 50 ml equipped with a Vigreux-type fractionating tube, a thermometer, and a nitrogen introducing tube similar to those in. All these raw materials were charged in a nitrogen gas atmosphere. Then, the reaction liquid charged while gradually reducing the pressure in the flask was gradually heated, adjusted to 180 ° C. and the pressure reduction degree to 200 torr, and refluxed for 1 hour. Next, when the pressure reduction degree was gradually increased while maintaining the reaction temperature at 180 ° C., phenol derived from diphenyl carbonate was distilled out.
When the reaction proceeded and the distillation of phenol was almost eliminated, the degree of vacuum was further increased and the reaction was completed by extracting 1,6-hexanediol. The degree of vacuum was finally 7 torr, and the total reaction time was 6 hours.

The total amount of phenol and 1,6-hexanediol withdrawn was 22.63 g, and the composition of the components was 1,6-hexanediol; 21.0% by weight and phenol; 79.0% by weight. It was The yield of the obtained polycarbonate diol was 15.25 g. Then, when the hydroxyl value of this polycarbonate diol was measured, it was 74.9 mgKOH / g,
The number average molecular weight determined by the above formula (I) is 1500.
Met.

Also, the same 400 as used in Example 1 was used.
When the structural analysis of the above polycarbonate diol was carried out using a MHz NMR analyzer, a phenoxy group derived from the starting material diphenyl carbonate was not confirmed at the molecular end. Further, since no vinyl group generated as a result of the dehydration reaction of the hydroxyl group at the molecular end was also confirmed, it was found that all the molecular ends of the obtained polycarbonate diol were hydroxyl groups. The ratio of the ether group contained in the molecular chain of the obtained polycarbonate diol is 0.42% with respect to the carbonate group.
Met. Further, when the melt color (APHA) was measured in order to examine the degree of coloring of the above polycarbonate diol, it was 200, and coloring was recognized.

[0037]

As described above, according to the method of the present invention, when a polycarbonate polyol is produced by a transesterification reaction of a diaryl carbonate and an aliphatic polyhydroxy compound, 1,6-dihydrogenated and purified.
By using hexanediol, there is no coloring,
In addition, it is possible to provide a high-quality polycarbonate polyol with less side reactions. Therefore, the polycarbonate polyol produced by the method of the present invention is used in various fields such as synthetic leather, elastomers and paints, and is excellent in heat resistance, weather resistance, hydrolysis resistance, etc., and economically high quality. It can be suitably used as a raw material for polyurethane.

Continuation of the front page (56) Reference JP-A-2-49025 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 64/00-64/42

Claims (4)

(57) [Claims] 1. A method for producing a polycarbonate polyol by a transesterification reaction of a diaryl carbonate and an aliphatic polyhydroxy compound, wherein an aliphatic polyhydroxy compound subjected to hydrogenation purification treatment is used as the aliphatic polyhydroxy compound. A method for producing a polycarbonate polyol. 2. The aliphatic polyhydroxy compound is 1,6-
The method for producing a polycarbonate polyol according to claim 1, which is hexanediol. 3. The production of a polycarbonate polyol according to claim 1, wherein the hydrogenation refining treatment is carried out in the presence of a noble metal catalyst at a temperature of 50 to 200 ° C. and a pressure of atmospheric pressure to 50 atmospheres. Method. 4. The method for producing a polycarbonate polyol according to claim 1, wherein the molar ratio of the aliphatic polyhydroxy compound to the diaryl carbonate is 1.01 to 3.00.