JPS5833244B2 - Manufacturing method of polytetramethylene glycol - Google Patents

Description

Detailed Description of the Invention The present invention relates to polytetramethylene glycol (hereinafter referred to as PTMG).
(abbreviated as )).

More specifically, the present invention utilizes tetrahydrofuran (hereinafter referred to as TH) using fluorosulfuric acid (hereinafter referred to as FSA) as a catalyst.
PTM is obtained by hydrolyzing the polymerization reaction product of
This invention relates to an improvement in a method for manufacturing G.

PTMG is produced by ring-opening polymerization of THF in the presence of a ring-opening polymerization catalyst and is used as a raw material for various polyurethanes and polyesters, but industrially valuable PTMG is a product with a molecular weight of about 650 to 2,500. is well known.

As a ring-opening polymerization catalyst for THF, F'SA, perchloric acid,
Pentafluoride and the like are known, but polymerization using FSA as a catalyst has the advantage that the terminal of the polymer can be easily converted into a hydroxyl group by simply hydrolyzing the polymerization reaction mixture with water. .

The molecular weight of PTMG is adjusted by increasing or decreasing the reaction temperature, reaction time, amount of catalyst used, etc. When FSA is used as a catalyst, 0.5 to 20% by weight of FSA is usually added to THF as a raw material, and This is carried out by reacting for several hours at a constant temperature of ~50°C.

However, the ring-opening polymerization of THF is an exothermic reaction, and the heat is concentrated in a short period of time at the beginning of the reaction (approximately 30 minutes), so when trying to keep the reaction temperature constant at the beginning of the reaction, Heat removal is required.

Conventionally, this heat removal is done by cooling, THF reflux, etc.
Temperature control was performed to keep the temperature constant from the beginning of the reaction, but this operation is not easy and becomes a problem, especially when producing low molecular weight PTMG that requires a large amount of catalyst, and the amplitude of the reaction temperature may become large. (Accurate molecular weight control is therefore difficult.

Furthermore, when the reaction temperature fluctuates significantly, the molecular weight distribution also tends to widen.

In view of these circumstances, the present inventors conducted extensive studies to find an industrially advantageous method for producing PTMG having an industrially valuable molecular weight of approximately 650 to 2,500. We have discovered a method that is more advantageous than conventional methods in terms of rate and control of the reaction, and have arrived at the present invention.

That is, the present invention involves polymerizing THF using FSA as a catalyst, adding water to the obtained polymerization reaction product, and hydrolyzing it to produce PTMG, in which substantially tetrahydrofuran and fluorosulfuric acid are mixed. The reaction mixture was allowed to reach the maximum reaction temperature solely by the heat generated by
The gist is to produce polytetramethylene glycol by cooling to 0°C to 45°C and reacting.

In a preferred embodiment of the invention, the maximum reaction temperature is 5
After reaching 0°C to 70°C, the reaction mixture is cooled to 30°C to 45°C within 1 hour and kept at this temperature for at least 2 hours.

Next, the present invention will be explained in more detail.

When THF is polymerized using FSA as a catalyst, the amount of FSA used varies depending on the molecular weight of the target PTMG, but
To obtain PTMG with a molecular weight of 650 to 2500, THF
The amount is selected from the range of 0.5 to 15% by weight, preferably 1 to 1% by weight.

The polymerization of THF is accompanied by rapid heat generation at the initial stage of the reaction, but the heat generated at this time is not removed at all or is removed only partially to allow the reaction mixture to reach the maximum temperature.

This maximum reaction temperature is preferably between 50°C and 70°C, more preferably between 55°C and 65°C, preferably kept at this temperature for no more than one hour to activate the catalyst, and then the reaction mixture preferably By maintaining the temperature at ℃ to 45℃, more preferably 35℃ to 45℃ for 2 hours or more,
Polymerization takes place.

As is well known, in the ring-opening polymerization of THF using an FSA catalyst, a proton of FSA is first added to the oxygen atom of THF to form a stable oxonium ion, and another THF molecule
Ring opening occurs by nucleophilic attack on the active methylene group adjacent to the oxygen atom in the oxonium ion, and then the active oxonium ion reacts with other THF molecules to open the ring.

It is presumed that similar reactions proceed one after another to form a long polymer chain with catalytic activity.

When producing polymers with the same molecular weight, the molecular weight is determined by the concentration of active species if the temperature is constant; the higher the concentration of active species, the lower the molecular weight, and the higher the concentration of active species is as the temperature increases for the same amount of catalyst. It is inferred that the value approaches a certain value.

Therefore, the purpose of the present invention is to allow heat to be generated by polymerization heat without removing heat during the initial stage of the reaction, where it is difficult to control the reaction temperature, and at the same time activate the catalyst to increase the active species concentration and increase the effective catalyst concentration. There is a particular thing.

However, the temperature increase due only to polymerization heat varies depending on the amount of catalyst or heat dissipation, but generally the temperature at the time of dropping FSA is set to 3.
If the temperature is below 0°C, it will hardly exceed 70°C, and deactivation of active species is expected at high temperatures.
It is desirable to set it as the range of 55 degreeC - 65 degreeC more preferably 70'C1.

On the other hand, the higher the reaction temperature, the lower the yield, 45°C to 50°C.
From the viewpoint of yield, it is desirable to lower the reaction temperature, but if it is lowered too low, it will take a long time to reach equilibrium and Because a large amount of catalyst must be used to obtain the polymer, the reaction temperature is preferably 30°C to 45°C.
℃, more preferably 35°C to 45°C, and in order to obtain a constant molecular weight, it is preferable to maintain the temperature for 2 hours or more.

As described in detail above, according to the present invention, PT
It is possible to manufacture MG.

The treatment after the completion of the polymerization reaction is carried out in the same manner as in the conventional method.

That is, water is added to the polymerization reaction mixture, which is heated to be hydrolyzed and, if desired, unreacted THF is recovered at the same time.

), separating the PTMG layer, then adding alkali,
Neutralizes the acid content generated by decomposition of the FSA catalyst and removes unreacted THF.
After recovering, organic solvents such as benzene, toluene, n-butanol, etc. are added, water is removed by azeotropic distillation, and salts are separated by filtration.

After filtration, the organic solvent is removed by vacuum distillation to obtain PTMG.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples unless the gist thereof is exceeded.

Example 1 After ice-cooling THF400S' and keeping it at 10°C, FSA30.6P was added dropwise while stirring.

The time required for dropping was 20 minutes.

At the same time as the dropwise addition started, water cooling was stopped, and the temperature rise due to heat generation of the reaction mixture was allowed to take its course.

As a result, the temperature rose to 56°C and then began to fall.

After reaching the maximum temperature, let it take its course for 10 minutes (this 10 minutes is the peak retention time).

), rapidly cooled to 35°C, then reacted at 35°C in a nitrogen stream for 5 hours with stirring, and then cooled to 400°C with water. Add and heat to 70℃5
Hydrolysis was carried out by stirring for hours.

When heating and stirring were stopped, the mixture was separated into a PTMG layer and an aqueous layer.

After removing the aqueous layer, 20 (l) of warm water was added and stirred at 70°C for 30 minutes to wash away the acid content in the PTMG layer.

Separate the aqueous layer by standing, neutralize the residual acid present in a small amount in the PTMG layer with calcium hydroxide, heat it to 100°C to recover unreacted THF, add toluene, and remove the remaining acid by azeotropic distillation. Water was removed and salts formed during neutralization were filtered off.

After filtration, toluene is removed by vacuum distillation, resulting in a colorless (AP
A transparent PTMG with a molecular weight of 1480 was obtained.

The yield at this time was 685%.

In addition, the molecular weight is a calculated value from the OH value determined by the phthalic anhydride method, and the yield is the value calculated from the OH value determined by the phthalic anhydride method.
This is a value determined by the following formula by analyzing F.

Comparative Example 1 Same as Example 1 <THF400f was ice-cooled to 10°C, and F
SA30.6f was added dropwise over 20 minutes.

When the temperature of the reaction mixture rose to 35°C, it was cooled with ice, and then reacted with stirring at 35°C in a nitrogen stream for 5 hours.

Hydrolysis and post-treatment were carried out in the same manner as in Example 1, and as a result, PTMG with a molecular weight of 1600 was obtained, with a yield of 63.0%.

Examples 2 to 8 (Comparative Examples 2 to 5) THF set temperature at the start of FSA dropping in Example 1,
Table 1 shows the results of experiments conducted by changing the amount of catalyst, catalyst activation conditions (maximum reaction temperature and peak retention time), or reaction temperature after activation.

The comparative example in Table 1 is an experimental example in which the reaction temperature was kept constant from the initial stage of the reaction, similar to comparative example 1.

Claims (1)

[Claims] 1. In a method for producing polytetramethylene glycol by polymerizing tetrahydrofuran using fluorosulfuric acid as a catalyst, adding water to the resulting polymerization reaction mixture, and hydrolyzing the mixture, substantially tetrahydrofuran and A method for producing polytetramethylene glycol, which comprises allowing the reaction mixture to reach the maximum reaction temperature using only heat generated by mixing with fluorosulfuric acid, and then cooling the reaction mixture to 30°C to 45°C for reaction. 2. In the method for producing polytetramethylene glycol according to claim 1, the maximum reaction temperature is 50°C to 70°C.
After reaching ℃, the reaction mixture was heated from 30℃ to 4℃ within 1 hour.
A method characterized by cooling to 5°C and maintaining this temperature for 2 hours or more. 3. In the method for producing polytetramethylene glycol according to claim 1, the maximum reaction temperature is 55°C to 65°C.
℃. 4 In the method for producing polytetramethylene glycol according to claim 2, the reaction mixture is heated at 35°C to 45°C.
A method characterized by cooling to ℃.