JP2001316311A - Highly pure 1,5-pentanediol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce 1,5-pentanediol free from impurities to lower the polymerization reaction rate in the case of using the diol as a soft segment of polycarbonate diol and polyester polyol or as a chain extender as it is for a raw material of polyurethane, polyester resin, etc. SOLUTION: The 1,5-pentanediol contains <=0.1 wt.% each of 1,5-hexanediol and 1,4-dihydroxycyclohexane. The 1,5-pentanediol can be produced by the direct hydrogen reduction of a dicarboxylic acid mixture in the filtrate obtained by the crystallization and separation of adipic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to pentanediol, and more particularly to 1,5-pentanediol containing no substance that inhibits the polymerizability at the time of production, such as polyurethane or polyester.

[0002]

2. Description of the Related Art 1,5-pentanediol is a useful substance as a raw material for polyester resins, urethane foams, urethane paints and adhesives. For example, as a raw material of polyurethane, it can be used as it is as a chain extender, or can be used as a soft segment in the production of polycarbonate diol, polyester polyol and the like. In particular, 1,5-pentanediol and 1,6
-Copolymerized polycarbonate diol obtained from hexanediol (see Japanese Patent Publication No. 5-029648)
Thermoplastic polyurethane made from it (JP-B 7-6)
No. 84), a thermoplastic polyurethane made from a polycarbonate diol obtained solely from 1,6-hexanediol has excellent properties such as hydrolysis resistance and heat resistance, and also has disadvantages of flexibility and elastic recovery. In recent years, it has attracted attention because it can be easily spun in the production of polyurethane fibers.

[0003] Such 1,5-pentanediol has heretofore been used as a carboxylic acid mixture containing glutaric acid, adipic acid and 6-hydroxycaproic acid as a by-product when cyclohexane is air-oxidized to produce cyclohexanone and / or cyclohexanol. And then hydrogenated using a copper-based catalyst to give 1,5-pentanediol and 1,6-hexanediol, which are separated by distillation (U.S. Pat. 268,
No. 588). However, as a result of the study by the present inventors, polycarbonate diol was produced using 1,5-pentanediol obtained by the above method as a raw material,
It has been found that when this is used as a raw material to carry out a urethanization reaction, the polymerization rate is slow and a sufficient molecular weight cannot be obtained, and a similar problem occurs when a chain extender is used as it is in the urethanization reaction. In addition, there is a problem that a similar effect is exerted on the polymerization rate during the production of polyester.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-purity 1,5-pentanediol which does not substantially contain impurities which lower the polymerization rate during the production of urethane or polyester. Do it.

[0005]

Means for Solving the Problems The present inventors have conducted various studies on the reason why a sufficient polymerization rate cannot be obtained in the urethanization reaction, and found that the 1,5-
Pentanediol contains 0.2 to 1% by weight of 1,5-hexanediol and 1,4-dihydroxycyclohexane, and 1,5-pentanediol having a small content thereof is used in the urethanization reaction. And found that a high polymerization rate was obtained, and completed the present invention. That is, the present invention provides (1) 1,5-pentanediol, wherein the contents of 1,5-hexanediol and 1,4-dihydroxycyclohexane are each 0.1% by weight or less, (2) 1, 5 described in (1), which is used as a raw material for producing polyurethane.
-Pentanediol.

Hereinafter, the present invention will be described in detail. The 1,5-hexanediol contained in the 1,5-pentanediol obtained by the conventional method is a diol having a secondary OH group and a primary OH group. When a polycarbonate diol is produced, the secondary OH group becomes a terminal group of the polycarbonate diol due to low reactivity, and when a urethane-forming reaction is performed using such a polycarbonate diol, a polyurethane having a low polymerization rate and a sufficient molecular weight is obtained. I found that I couldn't do it. It was also found that a polyurethane having a sufficient molecular weight could not be obtained for the same reason even when used directly as a chain extender in the urethanization reaction. Also, 1,4-dihydroxycyclohexane is 2
Each of the OH groups was a secondary OH group, which became a terminal group during the production of polycarbonate diol similarly to 1,5-hexanediol, and significantly reduced urethanization reactivity. Further, it was also found that the polymerization rate was affected during the polymerization to polyester.

Therefore, as a result of intensive studies by the present inventors,
1,5-pentanediol in which the contents of 1,5-hexanediol and 1,4-dihydroxycyclohexane are each 0.1% by weight or less exhibits high polymerization reactivity in the urethanization reaction, and is suitable as a raw material for polyurethane. I found something. Also, it was found that a favorable effect on the polymerization rate was obtained also during the polymerization into the polyester. Preferably, the content of 1,5-hexanediol and 1,4-dihydroxycyclohexane is 0.0
5% by weight or less. Needless to say, 1,5-pentanediol which does not substantially contain impurities such as 1,5-hexanediol and 1,4-dihydroxycyclohexane is also useful when used as a fine chemical raw material such as a raw material for medical and agricultural chemicals. . The water content in the 1,5-pentanediol of the present invention is preferably 0.3% by weight or less, more preferably 0.2% by weight or less.
If the water content is more than 0.3% by weight, for example, the catalyst is deactivated during the production of polycarbonate diol, or when used as it is as a chain extender, the organic isocyanate and water react and the molecular weight does not increase. .

Further, lactones such as δ-valerolactone and ε-caprolactone, hydroxycarboxylic acids such as 5-hydroxyvaleric acid and 6-hydroxycaproic acid, and monoalcohols such as pentanol and hexanol are 1,1.
Compounds which may be mixed in during the production of 5-pentanediol, the total content of these compounds in 1,5-pentanediol is preferably 0.5% by weight or less, more preferably 0.3% by weight or less. % By weight or less. The 1,5-pentanediol of the present invention may contain 1,4-butanediol and / or 1,6-hexanediol as desired. For example, as a raw material of the above-mentioned copolymerized polycarbonate diol, a mixture of 1,5-pentanediol and 1,6-hexanediol can be preferably used.

The reason that the above-mentioned impurities are contained in 1,5-pentanediol produced by the conventional method is that cyclohexane, which is a raw material thereof, is oxidized by air to obtain cyclohexanone and / or cyclohexanone.
Alternatively, a carboxylic acid mixture containing glutaric acid, adipic acid, and 6-hydroxycaproic acid, which is a by-product of producing cyclohexanol, undergoes hydrogen reduction to 1,5-hexanediol and 1,4-dihydroxycyclohexane. It is presumed that impurities are contained. As a method for obtaining 1,5-pentanediol of the present invention, glutaric acid produced as a by-product during the production of cyclohexanone and / or cyclohexanol is esterified and then purified by a method such as distillation to obtain a glutaric acid diester. The purity may be 99.9% by weight or more, which may be hydrogen-reduced using a copper-based catalyst to give 1,5-pentanediol, but the purification of glutaric acid diester requires a great deal of labor. .

Further, the 1,5-pentanediol obtained after hydrogenation of an ester according to the conventional method is further purified by distillation.
The boiling point of 4-dihydroxycyclohexane is close to that of 1,5-pentanediol and is difficult. Glutaric acid, which is a raw material of 1,5-pentanediol, is not only the above-mentioned by-product of producing cyclohexanone and / or cyclohexanol, but also nitric acid oxidation of cyclohexanone and / or cyclohexanol to produce adipic acid. And a mixture of glutaric acid, succinic acid, and adipic acid which are by-produced.

As a result of extensive studies by the present inventors, 1,5-pentanediol obtained by hydrogen reduction using this by-product dicarboxylic acid mixture as a raw material is 1,5-hexanediol and 1,4-dihydroxycyclohexane. Are each 0.1% by weight or less,
It was found to be 5-pentanediol. That is, glutaric acid by-produced when nitric acid oxidizes cyclohexanone and / or cyclohexanol to produce adipic acid,
Succinic acid or adipic acid is directly or esterified and then hydrogen reduced to a diol, and if necessary, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol are purified by a purification method such as distillation. By separating, the 1,5-pentanediol of the present invention can be obtained.

The above dicarboxylic acid mixture is preferably subjected to a treatment for removing copper and vanadium used as a catalyst for oxidizing nitric acid and nitric acid contained therein before subjecting the mixture to hydrogen reduction.
In the presence of nitric acid, the metal used as a catalyst for hydrogen reduction dissolves in the solution, and the activity of the catalyst decreases with time. As a method for removing nitric acid, a method in which an aqueous solution of a dicarboxylic acid mixture is heated under normal pressure or reduced pressure to remove water and most of nitric acid, and further heated at a temperature of 130 ° C to 180 ° C for 1 minute to 1 hour. Simple and preferred. It is preferable to further purify the dicarboxylic acid mixture using activated carbon, an anion exchange resin, or the like, since the activity of the catalyst in hydrogen reduction becomes higher and a diol can be obtained stably for a long period of time.

[0013] The 1,5-pentanediol of the present invention can be obtained by performing hydrogen reduction using the above dicarboxylic acid mixture as a raw material. As a method of hydrogen reduction, a dicarboxylic acid mixture may be reacted with an alcohol such as methanol or ethanol to form an ester, and then reacted with hydrogen using a copper-based catalyst.However, ruthenium and tin in the presence of water may be used. A method in which the dicarboxylic acid mixture is directly hydrogen-reduced with hydrogen using a catalyst containing is preferred since the number of steps is short.

As a catalyst containing ruthenium and tin used for direct hydrogen reduction of dicarboxylic acids, a catalyst further containing rhenium and / or platinum is preferred because of its high activity. As the carrier, activated carbon, silica, alumina, titania,
A porous substance such as zirconia can be used, and among them, activated carbon is particularly preferable. The amount of water in the hydrogen reduction is preferably such that the dicarboxylic acid mixture is dissolved at the hydrogen reduction temperature, and specifically, the concentration of the dicarboxylic acid solution is in the range of 1% by weight to 50% by weight. The temperature is preferably from 100C to 300C, more preferably from 140C to 250C. Pressure is 1MPa ~ 25MP
a is preferable, and more preferably, 5 MPa to 20 MPa.
It is. The reaction time can be arbitrarily selected depending on the temperature and pressure conditions, but it is difficult to select hydrogenation conditions such that lactones, which are intermediates for hydrogen reduction, are 0.5% by weight or less in 1,5-pentane. This is preferable because the load on the purification system of the diol can be reduced. Hydrogen reduction can be carried out batchwise or continuously. The obtained 1,5-pentanediol can be dehydrated and purified by a method such as distillation.

As a method for producing a polycarbonate diol, a polyester polyol, a polyester resin, and a polyurethane using the 1,5-pentanediol of the present invention, a conventionally known method can be used.
For example, the synthesis of polycarbonate diol is described in Polym
er Reviews, Vol. 9, pages 9-20, according to the method described in dialkyl carbonate and 1,
The reaction can be carried out by reacting 5-pentanediol with a general transesterification catalyst. As a method for synthesizing without a catalyst, a method using ethylene carbonate or diphenyl carbonate has been conventionally known, and these methods can also be applied. The polyester polyol can be synthesized from a dicarboxylic acid such as adipic acid and 1,5-pentanediol by a dehydration reaction in the absence or presence of a catalyst. It can also be synthesized from a dicarboxylic acid diester and 1,5-pentanediol by a transesterification reaction.

As a method for producing polyurethane from these polycarbonate diols or polyester polyols, a urethanization technique known in the polyurethane industry is used. For example, an NCO-terminated polyurethane prepolymer is produced by reacting the polyol with an organic isocyanate at room temperature to 200 ° C.
This can be used as a one-part solventless adhesive or sealant that cures by reacting with moisture in the air as desired.
In addition, the prepolymer, another polyol, and a known crosslinking agent can be used in combination as a two-pack type casting material.

Examples of the organic isocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and a mixture thereof (TDI), diphenylmethane-4,4'-diisocyanate (MDI), and naphthalene-1,5-diisocyanate. (NDI), 3,3'-dimethyl-4,4'-biphenylene diisocyanate (T
ODI), crude TDI, polymethylene polyphenyl isocyanate, phenylene diisocyanate, crude MDI
, Such as known aromatic diisocyanate and xylylene diisocyanate (XDI), 4,4'-methylenebiscyclohexyl diisocyanate (hydrogenated MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IP
DI), known aliphatic diisocyanates such as cyclohexane diisocyanate, and modified isocyanurates and modified carbodiimides of these isocyanates;
A bullet-modified product or the like can be used.

Also, a method of producing a crosslinked or thermoplastic polyurethane by using a method such as a one-shot method, a prepolymer method, or a RIM method, using the polyol and the polyisocyanate and, if necessary, a chain extender. Can be. In these production methods, known polymerization catalysts typified by organic metal salts such as tertiary amines, tin, titanium, and lead (for example, "Polyurethane resin" by Keiji Iwata, published by Nikkan Kogyo Shimbun, pp. 23-32) (See (1969)). These reactions may be carried out using a solvent. Preferred solvents include dimethylformamide, diethylformamide, dimethylsulfoxide, dimethylacetamide, tetrahydrofuran, methylisobutylketone, dioxane, cyclohexanone, benzene, toluene, ethylcellosolve and the like. Is mentioned. Further, the 1,5-pentanediol of the present invention can be used as it is as a chain extender in the production of polyurethane. Further, polyester polyols and polyester resins are also used as plasticizers, adhesives and the like.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to examples and the like. The analysis of 1,5-pentanediol was performed by gas chromatography.
The analysis method is as follows. Analysis conditions of gas chromatography: column; DB-WAX (manufactured by J & W), 30 m, film thickness 0.25 μm, heating condition: 60 ° C.
250 ° C., detector: FID. The solution was analyzed using a solution in which the 1,5-pentanediol concentration was adjusted to several weight%. The molecular weight analysis of the polycarbonate diol and the polyurethane was performed using GPC.

[0020]

Example 1 <Synthesis of 1,5-pentanediol> An aqueous solution of a by-product dicarboxylic acid mixture obtained from an adipic acid production facility was heated to a temperature of about 120 ° C for 1 hour, and then heated to 170 ° C to 175 ° C. Stirring was maintained for 30 minutes. The remaining solid was made into a 38% by weight aqueous solution with ion exchanged water. 1000 g of this aqueous solution and a styrene-based cation exchange resin (manufactured by Organo Corporation, trade name: Amberlite IR120B) 30
After contacting 0 g at room temperature for 2 hours, the mixture was filtered, and the filtrate was used as a raw material for hydrogen reduction. The concentration of the dicarboxylic acid was 38% by weight, and the composition of the dicarboxylic acid was 20% by weight of succinic acid, 50% by weight of glutaric acid, and 30% by weight of adipic acid.

The above dicarboxylic acid mixture is converted to chloroplatinic acid
6.0% by weight of ruthenium prepared by impregnation from hexahydrate, tin (II) chloride, ruthenium trichloride trihydrate and activated carbon as a carrier, followed by drying and reduction treatment with hydrogen.
Hydrogen was directly reduced by the following method using a catalyst in which 5.0% by weight of tin and 3.5% by weight of platinum were supported on activated carbon. SUS
600 g of the above dicarboxylic acid aqueous solution and 10 g of the above catalyst were charged into a 1000 ml autoclave made of 316 (stainless steel), the atmosphere in the autoclave was replaced with nitrogen at room temperature, hydrogen was injected at 2 MPa, and the temperature was raised to 180 ° C.
When the temperature reaches 180 ° C, hydrogen is further injected and 15 MPa
And Hydrogen reduction was performed at this pressure for 30 hours. After hydrogen reduction, the reaction solution and the catalyst were separated by filtration, and 600 g of the separated catalyst and the above dicarboxylic acid mixture were charged again into an autoclave, and hydrogen reduction was performed under the same conditions. This hydrogen reduction was repeated 10 times in total to obtain about 6 kg of a hydrogen reduced liquid.

The above hydrogen reducing solution was heated to 109 ° C. under normal pressure, and most of the water was distilled off. Next, the remaining liquid was distilled using a 12-stage distillation column to distill off water and low-boiling compounds such as pentanol. The residual liquid was distilled under reduced pressure using a 35-stage distillation column, and 1,4-butanediol and a trace amount of 1,5-
A fraction containing pentanediol was obtained. The bottom liquid after distillation of 1,4-butanediol is distilled under reduced pressure using a 35-stage distillation column to give 1,5-pentanediol and a trace amount of 1,4-butanediol and 1,6-butanediol. A fraction containing hexanediol was obtained. The obtained 1,5-pentanediol was 860 g. Analysis by gas chromatography revealed a purity of 99.0%;
-Butanediol was 0.09% by weight and 1,6-hexanediol was 0.29% by weight, and it was confirmed that 1,5-hexanediol and 1,4-dihydroxycyclohexane were 0.01% by weight or less.

<Production of Polycarbonate Diol> 833 g (8.0 mol) of 1,5-pentanediol obtained above was added to a reactor equipped with a stirrer, a thermometer, and a fractionating tube. 1.84 g of sodium
(0.08 mol) was added with stirring. After the sodium has completely reacted, 944 g of diethyl carbonate
(8.0 mol) was introduced. 95 ° C reaction temperature at normal pressure
As the temperature was raised to １００100 ° C., ethanol began to distill.
The temperature was gradually raised to 160 ° C. in 6 hours. During this time, ethanol containing about 10% of diethyl carbonate was distilled off. Thereafter, the pressure in the reactor was further reduced to 10 mmHg or less, and the reaction was carried out at 200 ° C. for 4 hours with vigorous stirring while extracting ethanol. The resulting polymer was cooled, dissolved in dichloromethane, neutralized with a dilute acid, dehydrated with anhydrous sodium sulfate, and the solvent was distilled off.
Dry at 140 ° C. for several hours at mHg. 1,5 obtained
-The polycarbonate diol of pentanediol was a white solid at room temperature, and had an OH value of 57.0 mg / KOH.

<Production Example of Polyurethane>
11. polycarbonate diols of pentanediol
6 g was dissolved in 90.0 g of dimethylformamide, and 2.50 g of diphenylmethane-4,4'-diisocyanate was dissolved.
g (the equivalent ratio of MDI to polycarbonate diol is 1.
56) was added and mixed at 50 ° C. for 1.5 hours. After cooling the reaction solution to room temperature, a solution prepared by dissolving 0.20 g of ethylenediamine in 30 g of dimethylformamide was added, and 3
Mix for 0 minutes at room temperature. When the molecular weight of the obtained polyurethane was analyzed by GPC, Mn was 711,000 and Mw was 151,000 in terms of polystyrene. The tensile strength of the obtained polyurethane was 36 MPa, and the elongation was 560%. (JIS-K6251, No. 3 dumbbell, a 2 mm thick pressed sheet was used as a sample.)

[0025]

Comparative Example 1 Commercially available 1,5-pentanediol was analyzed by gas chromatography to find that the purity of 1,5-pentanediol was 98.9%, and 0.62% by weight of 1,5-hexanediol and 0.27% by weight of 1,4-
It contained dihydroxycyclohexane. Using this, a polycarbonate diol of 1,5-pentanediol was synthesized in the same manner as in Example 1. The obtained polycarbonate diol was a white solid at room temperature, and had an OH value of 62.2 mg / KOH.

The polycarbonate diol was prepared in Example 1
A polyurethane was synthesized in the same manner as in Example 1 except that 11.5 g was used so that the equivalent ratio between MDI and polycarbonate diol became 1.56. The molecular weight of the obtained polyurethane was analyzed by GPC.
n was 626,000 and Mw was 120,000. The obtained polyurethane has a tensile strength of 25 MPa and an elongation of 400.
%Met. (JIS-K6251, No. 3 dumbbell, a 2 mm thick pressed sheet was used as a sample.)

[0027]

According to the present invention, there is provided a high-molecular-weight, substantially free of 1,5-hexanediol and 1,4-dihydroxycyclohexane, which are impurities that lower the polymerization rate during the production of polyurethane or polyester. It has become possible to provide 1,5-pentanediol which is suitable as a raw material enabling production of polymers such as polyurethane.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4H006 AA02 AC41 AC46 AD11 BD10 BD70 BE20 FE11 FG29 4J034 CA01 CA04 CB03 CC03 DA01 DB04 DF01 DF02 HA01 HA06 QA07

Claims (2)

[Claims] 1. A method according to claim 1, wherein said 1,5-hexanediol and 1,4-
1,5-pentanediol, wherein the content of dihydroxycyclohexane is each 0.1% by weight or less. 2. The 1,5-pentanediol according to claim 1, which is used as a raw material for producing polyurethane.