JP2000095855A - Production of polycarbonate polyol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject polyol scarcely causing side reactions without discoloration and useful as a raw material for polyurethanes for synthetic leathers by using an aliphatic polyhydroxy compound subjected to a hydrogenation refining treatment. SOLUTION: When carrying out a transesterification of (A) a diaryl carbonate (e.g. diphenyl carbonate) with (B) an aliphatic polyhydroxy compound (e.g. ethylene glycol), an aliphatic polyhydroxy compound subjected to a hydrogenation refining treatment is used as the component B. Furthermore, the component B is preferably 1,6-hexanediol and the hydrogenation refining treatment is preferably conducted at 50-200 deg.C temperature under a pressure of atmospheric pressure to 50 atm in the presence of a noble metal catalyst. The component B is preferably used in 1.01-3.00 molar ratio to the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a polycarbonate polyol used as a raw material of polyurethane used in various fields such as synthetic leather, elastomer, and paint. More specifically, the present invention relates to a method for producing a polycarbonate polyol with less coloring and less side reactions by a transesterification reaction between 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, JP-B-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.
-Polytitanate, tetra-n-butyltitanate and other basic compounds and organometallic compounds as catalysts for producing polycarbonate polyols (JP-A-61-15)
No. 1235, JP-A-62-187725, JP-A-64-118, JP-A-2-49025, JP-A-2-175721, etc.) are known. However, in these production methods, there is a problem that, for example, a polycarbonate polyol generated from a diaryl carbonate such as diphenyl carbonate is more colored than a case where a dialkyl carbonate such as dimethyl carbonate or diethyl carbonate is used as a raw material.

On the other hand, it has been reported that in a process for producing a polycarbonate polyol using an aliphatic carbonate compound, for example, a dialkyl carbonate such as dimethyl carbonate or diethyl carbonate as a raw material, a transesterification catalyst is used because of a low transesterification rate. (JP-A-51-83693, JP-A-51-836)
94, JP-A-61-151263, JP-A-2-151
284918, JP-A-2-284919, etc.).

For example, in the above-mentioned method for producing a polycarbonate polyol, if a basic alkali metal salt or alkaline earth metal salt is used as a transesterification catalyst, the reaction rate is increased, but a side reaction occurs and both ends are hydroxyl groups. In addition, when producing a polyurethane from this polycarbonate polyol, an abnormal reaction occurs with an isocyanate, and the urethanization reaction cannot be controlled. In addition, when an organometallic compound such as an alkoxide of titanium or tin is used as the transesterification catalyst, a side reaction is suppressed and a polycarbonate polyol with less coloring can be produced. However, when polyurethane is produced using this polycarbonate polyol, it is difficult to control the urethanization reaction with the isocyanate compound due to the effect of the remaining catalyst, or gelation occurs during the reaction. Inactivation treatment (see, for example, JP-A-64-1724) must be performed, and is not industrially economical. Also, when adding a Bronsted acid or an acidic alkali metal salt or alkaline earth metal salt, these additives do not have a catalytic action,
The transesterification reaction between the aliphatic carbonate compound and the polyhydroxy compound does not proceed.

Further, Japanese Patent Application Laid-Open No. Sho 64-1726 discloses that a diaryl carbonate which has been purified by an adsorption treatment with an inorganic adsorbent such as activated clay, acid clay, or diatomaceous earth, and a polyhydroxy compound are esterified. A method of producing a high-quality polycarbonate polyol with little coloration by performing an exchange reaction, and JP-A-60-181125 discloses an epoxy group-containing compound having at least one epoxy group 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 less coloring,
Each is disclosed.

[0006]

However, the above-mentioned Japanese Patent Application Laid-Open Nos. 64-1726 and 60-1811 disclose the methods described above.
The methods described in Japanese Patent Publication No. 25 are all directed to the case where, for example, diphenyl carbonate obtained by reacting phenol with phosgene is used as a raw material diaryl carbonate. Therefore, in order to prevent a side reaction and / or coloring of the polycarbonate polyol, the method described in JP-A-64-1726 requires a purification step of previously adsorbing and removing a trace amount of a halogen component in the raw material diaryl carbonate. In the method described in JP-A-60-181125, hydrogen halide which is originally present in the raw material diaryl carbonate or is generated during the transesterification reaction is reacted with the epoxy group-containing compound. It is necessary to discharge the hydroxyl group-terminated compound produced outside the system out of the system, the process is complicated, and it is not economical as a method for producing a polycarbonate polyol. In Japanese Patent Application Laid-Open No. 60-181125, dialkyl carbonate compounds and the like used for the production of polycarbonate are generally required to be purified by advanced washing or distillation, but in this method, washing with a normal alkaline aqueous solution is required. And the dicarbonate compound of the quality obtained by distillation can be sufficient.
Although there is a description that high-level purification of the raw material is not required, there is no description about a purification treatment of a polyhydroxy compound which is another raw material for producing a polycarbonate polyol. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a polycarbonate polyol having no coloration and having less side reaction from a diaryl carbonate and an aliphatic polyhydroxy compound.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, when producing a polycarbonate polyol by transesterification from a diaryl carbonate and an aliphatic polyhydroxy compound, By using an aliphatic polyhydroxy compound that has been subjected to hydrogenation (hereinafter referred to as "hydrogenation") purification treatment, it has been found that a polycarbonate polyol without coloring and with less side reaction can be obtained.
The present invention has been completed.

According to a first aspect of the present invention, there is provided a method for producing a polycarbonate polyol by a transesterification reaction of a diaryl carbonate and an aliphatic polyhydroxy compound, wherein the aliphatic polyhydroxy compound is subjected to hydrogenation purification treatment. This can be achieved by providing a method for producing a polycarbonate polyol characterized by using an aliphatic polyhydroxy compound. The second aspect of the present invention can be achieved by providing the method for producing a polycarbonate polyol according to the first aspect, wherein the aliphatic polyhydroxy compound is 1,6-hexanediol. The third invention according to claim 3 is that the hydrorefining treatment is carried out in the presence of a noble metal catalyst by 50 to 2 hours.
This can be achieved by providing the method for producing a polycarbonate polyol according to the first or second invention, wherein the method is carried out at a temperature of 00 ° C. and a pressure of normal pressure to 50 atm.

A fourth aspect of the present invention is the fourth aspect of the present invention, wherein the molar ratio of the aliphatic polyhydroxy compound to the diaryl carbonate is from 1.01 to 3.00. This can be achieved by providing a method for producing one of the polycarbonate polyols.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention will be described below in detail. The aryl group of the diaryl carbonate used in the present invention may have various substituents, and the types of 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. As the carbonate, diphenyl carbonate is particularly preferred.

The 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,
-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, and 1,3-cyclohexane Diols, 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, hexanetriol, and pentaerythritol, dipentaerythritol, diglycerin And sorbitol and the like. These aliphatic polyhydroxy compounds can be used alone or as a mixture of two or more.

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

When the noble metal catalyst is used in a batch reaction, the amount of the noble metal catalyst is 0.1 to 10000 ppm, preferably 1 to 1000 ppm, as a metal element, based on the weight of the aliphatic polyhydroxy compound. When the amount of the catalyst 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 between the aliphatic polyhydroxy compound and the diaryl carbonate is colored. May be. On the other hand, when the use amount of the catalyst is more than 10000 ppm, there is no advantage in hydrotreating the aliphatic polyhydroxy compound such that the aliphatic polyhydroxy compound is decomposed, and it is not economical.

The reaction temperature is preferably 50 to 200 ° C., and more preferably 80 to 160 ° C., under the conditions for the hydrogenation purification treatment of the aliphatic polyhydroxy compound. 50 ℃
At lower temperatures, the hydrorefining process takes a long time and is not industrially suitable. If the temperature exceeds 200 ° C., the aliphatic polyhydroxy compound is decomposed, so that it is not economical. Further, the pressure of the supplied hydrogen 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 the hydrogenation and purification treatment of the aliphatic polyhydroxy compound takes too much time. 5
Even if the pressure exceeds 0 atm, a special pressure resistance performance is required for the reactor, which is not industrially economical. In the method of the present invention, the reaction type of the hydrotreating treatment of the aliphatic polyhydroxy compound may be either a batch system or a continuous system. The reaction apparatus is not particularly limited,
For example, in the case of a batch method, in an autoclave,
In the case of a continuous system, the hydrogenation reaction may be performed in a fixed bed column or the like. As the aliphatic polyhydroxy compound subjected to the hydrogenation purification treatment as described above, a product obtained by filtering the noble metal catalyst can be used as it is, but it does not prevent the further purification treatment by washing or distillation.

When a polycarbonate polyol is produced by the method of the present invention, the ratio of the charged aliphatic polyhydroxy compound is preferably 1.01 to 3.00 in terms of a 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 larger than 3.00, there is no advantage in the transesterification reaction between the diaryl carbonate and the aliphatic polyhydroxy compound, and an excess amount of the aliphatic polyhydroxy compound must be distilled off. It is industrially uneconomical.

The reaction temperature for producing the polycarbonate polyol of the present invention is not particularly limited,
The temperature is desirably 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 occurs as a side reaction, and an ether bond may be formed in a molecule of the obtained polycarbonate polyol or a vinyl group may be formed at a molecular terminal. On the other hand, when the temperature is low, the transesterification rate is low, and an extremely long reaction time is required, and the yield of the product is not economical.

The reaction pressure is not particularly limited, and the reaction can be carried out under any of pressurized, normal and reduced pressures. The hydroxyaryl compound derived from the diaryl carbonate used in the present invention can be used. And the boiling point of the aliphatic polyhydroxy compound. For example, at 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 for about several hours at about 150 to 220 ° C. For several hours by a transesterification reaction between the diaryl carbonate and the aliphatic polyhydroxy compound.

The reactor used in the method of the present invention is not particularly limited, and a tank-type reactor or a tubular reactor may be used. It is desirable to use a reactor equipped with a distillation column as a device capable of separating the raw material from a diaryl carbonate or an aliphatic polyhydroxy compound.

In the transesterification reaction of the present invention, it is necessary to continuously withdraw the generated hydroxyaryl compound out of the system to proceed with the reaction. Therefore, in order to assist the extraction of the hydroxyaryl compound out of the system, a small amount of an inert gas such as nitrogen, argon, and helium may be subjected to the reaction while flowing under reduced pressure, normal pressure, or increased pressure, The reaction may be carried out by filling the inert gas under normal pressure or under pressure.

Furthermore, in the process of the present invention, the transesterification catalyst may or may not be present in the production of the polycarbonate polyol. When a transesterification reaction between the diaryl carbonate and the aliphatic polyhydroxy compound is performed in the presence of a transesterification catalyst, a catalyst generally 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, acetylacetone titanium, etc.).

Examples of other suitable catalysts include inorganic acids such as titanic acid (IV), organic acids, and halides of the above metals (eg, halogenated compounds such as titanium trichloride, titanium tetrachloride and titanium tetrafluoride). Titanium, etc.), oxides (inorganic oxides such as zinc oxide, antimony trioxide, germanium dioxide, cerium trioxide, etc., 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 chloride titanate, ammonium chloride titanate, fluoride) Ammonium titanate, titanium sulfate, etc.) and organic acid salts (acetates 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 organic titanium compounds such as n-octyl titanate and tetraphenyl titanate, and organic tin compounds such as dibutyltin diacetate and dibutyltin dilaurate.

These transesterification catalysts are used in an amount of 0.0001 to 1.01% of the total weight of the starting material, the diaryl carbonate and the aliphatic polyhydroxy compound.
0% is appropriate, and preferably 0.001 to 0.2%. If the amount of the catalyst 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 slowed, and the yield of the polycarbonate polyol may be reduced. Further, even if the starting material is used in an amount of more than 1.0% of the total weight, there is no advantage in the transesterification reaction of the diaryl carbonate and the aliphatic polyhydroxy compound, and 1.0% is necessary and sufficient. It is.

In the method of the present invention, the use of the aliphatic polyhydroxy compound obtained by the hydrogenation treatment in advance as described above enables the production of a high-quality polycarbonate polyol without coloring. Can be. Although the reason for this is not clear, by the hydrorefining treatment, trace amounts of aldehydes and ketones contained in the aliphatic polyhydroxy compound used as a raw material are converted into alcohol compounds, and compounds having a double bond are converted into saturated hydrocarbon compounds. It is presumed that the conversion resulted in the elimination of side reactions due to the attack of the hydroxyaryl compound or diaryl compound.

[0024]

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 by these Examples and Comparative Examples. In the following Examples and Comparative Examples, various physical properties of the obtained polycarbonate polyol were respectively
It was determined by the following method.

(1) Hydroxyl value (OHv) According to JIS K1557, a sample (polycarbonate polyol) was esterified with phthalic anhydride, and after the reaction, the excess phthalic anhydride was measured by back titration with sodium hydroxide.

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

[0027]

(Equation 1)

(3) Melt color (APHA) A predetermined amount of a sample (polycarbonate polyol) was taken in a colorimetric tube according to JIS K1557, and determined by comparing with an APHA standard solution.

(4) Content of ether group contained in molecular chain The NMR of the sample (polycarbonate polyol) was measured to determine the content ratio (%) of the ether group to the carbonate group. The instrument used for NMR measurement is GSX-400 (manufactured 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 hereinafter); 180 g and 2% by weight Pd-carbon powder; 0.5 g was put in an autoclave having an internal volume of 500 ml. Next, after replacing the autoclave with nitrogen gas, the autoclave was replaced with hydrogen gas, and the temperature was gradually increased.
° C. Subsequently, 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 purified 1,6-hexanediol; As a result of analysis of 1,6-hexanediol before and after the reaction by gas chromatography (manufactured by Shimadzu Corporation, model: GC-14B), the area percentages were 98.7% and 98.6, respectively.
%, And almost no deterioration was observed.

Thus, 21.01 g (0.098 mol) of diphenyl carbonate (manufactured by Tokyo Chemical Industry Co., Ltd., special grade reagent, molecular weight: 214.2, the same applies hereinafter) and 1,6-hexane subjected to the hydrogenation purification treatment Diol; 17.38
g (0.147 mol) were placed in a 50-ml flask equipped with a Vigreux-type fractionating tube, thermometer and nitrogen inlet tube. All of these raw materials were charged in a nitrogen gas atmosphere. Then, the reaction solution charged was gradually heated while depressurizing the inside of the flask, and the temperature was reduced to 180 ° C. and the degree of depressurization was 200 t.
It was adjusted to orr and refluxed for 1 hour. Next, while the reaction temperature was maintained at 180 ° C., the degree of pressure reduction was gradually increased, and phenol derived from diphenyl carbonate was distilled out. When the reaction progressed and the distillation of phenol almost disappeared, the reaction temperature was raised to 190 ° C., and the degree of reduced pressure was further raised, and 1,6-hexanediol was extracted to complete the reaction. Decompression degree is finally 13t
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 component composition 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 formula (I) was 4410.

The structure of the above polycarbonate diol was analyzed using a 400 MHz NMR analyzer (model: GSX-400, manufactured by JEOL Ltd.). As a result, a phenoxy group derived from a diaryl carbonate was found at the molecular terminal. In addition, since no hydroxyl group generated by a dehydration reaction of the hydroxyl group at the molecular terminal was confirmed, it was found that all the molecular terminals of the obtained polycarbonate diol were hydroxyl groups. The ratio of the ether group contained in the molecular chain of the obtained polycarbonate diol was 0.24% with respect to the carbonate group. Furthermore, in order to examine the degree of coloring of the polycarbonate diol, the molten color (APHA) was measured. As a result, it was 15, and no coloring was observed. By using hydrogenated and purified 1,6-hexanediol as the aliphatic polyhydroxy compound as a raw material, a high-quality polycarbonate diol without coloring was obtained.

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 hydrotreating treatment were used in Example 1. The mixture was placed in a 50 ml-volume flask equipped with the same Vigreux-type fractionation tube, thermometer and nitrogen inlet tube as described above. All of these raw materials were charged in a nitrogen gas atmosphere. Therefore, the reaction solution charged in the flask was gradually heated while reducing the pressure, and the mixture was refluxed for 1 hour at 180 ° C. and a reduced pressure of 200 torr. Next, while the reaction temperature was maintained at 180 ° C., the degree of pressure reduction was gradually increased, and phenol derived from diphenyl carbonate was distilled out.
When the reaction progressed and the distillation of phenol almost disappeared, the degree of reduced pressure was further increased, and the reaction was completed by extracting 1,6-hexanediol. The degree of vacuum finally reached 7 torr and the total reaction time was 6 hours.

The total withdrawal amount of phenol and 1,6-hexanediol was 22.63 g, and the component compositions were 1,6-hexanediol: 21.0% by weight and phenol: 79.0% by weight. Was. And 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.

The same 400 used in Example 1 was used.
Structural analysis of the polycarbonate diol using a MHz NMR analyzer revealed no phenoxy group derived from the starting material diphenyl carbonate at the molecular end. Also, no vinyl group formed as a result of the dehydration reaction of the hydroxyl group at the molecular terminal was found, indicating that all the molecular terminals of the obtained polycarbonate diol were hydroxyl groups. The ratio of the ether group contained in the molecular chain of the obtained polycarbonate diol was 0.42% with respect to the carbonate group.
Met. Furthermore, in order to examine the coloring degree of the polycarbonate diol, the molten color (APHA) was measured.

[0037]

As described above, according to the method of the present invention, when producing a polycarbonate polyol by transesterification of a diaryl carbonate and an aliphatic polyhydroxy compound, 1,6-
By using hexanediol, there is no coloring,
In addition, a high-quality polycarbonate polyol having few side reactions can be provided. Therefore, the polycarbonate polyol produced by the method of the present invention is used in various fields such as synthetic leather, elastomer, and paint, and has excellent heat resistance, weather resistance, hydrolysis resistance, and the like, and is economically high-grade. It can be suitably used as a raw material for polyurethane.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takashi Doi 5F, 1978 Kogushi, Obe, Ube City, Yamaguchi Prefecture F-term in Ube Research Laboratory, Ube Research & Development Co., Ltd. 4J029 AA09 AB04 AC01 AD01 AD03 AE17 BA02 HA01 HC05A HC05B KA03 KB02 KE02 4J034 DF02 RA03 RA07

Claims (4)

[Claims] 1. A method for producing a polycarbonate polyol by a transesterification reaction between a diaryl carbonate and an aliphatic polyhydroxy compound, characterized in that a hydrogenated and purified aliphatic polyhydroxy compound is used as the aliphatic polyhydroxy compound. Of producing a polycarbonate polyol. 2. The method according to claim 1, wherein the aliphatic polyhydroxy compound is 1,6-
The method for producing a polycarbonate polyol according to claim 1, which is hexanediol. 3. The process for producing a polycarbonate polyol according to claim 1, wherein the hydrorefining treatment is carried out at a temperature of 50 to 200 ° C. and a pressure of normal pressure to 50 atm in the presence of a noble metal catalyst. Method. 4. The process for producing a polycarbonate polyol according to claim 1, wherein the molar ratio of the aliphatic polyhydroxy compound to the diaryl carbonate is from 1.01 to 3.00.