JPS61215621A - Production of polytetramethylene ether glycol - Google Patents

Abstract

PURPOSE:To produce a polytetramethylene ether glycol of stable quality, by hydrolyzing a polymer obtained by polymerizing tetrahydrofuran in the presence of a specified catalyst. CONSTITUTION:100pts.wt. tetrahydrofuran is polymerized at 10-50 deg.C for 3-10hr in the presence of 0.05-10pts.wt. HF, 0.2-20pts.wt. montmorillonite mineral and 0.5-20pts.wt. acetic anhydride. This polymerization is stopped by deactivating the catalyst by the addition of an aqueous alkali solution or the like. Catalyst residues are removed and unreacted tetrahydrofuran is recovered by distillation to leave a polymer. This polymer is mixed with an excess molar amount of an aqueous NaOH solution and, optionally, a solvent and hydrolyzed at 80-120 deg.C for 2-5hr to obtain a polytetramethylene ether glycol of a number- average MW of 500-4,000.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing polytetramethylene ether glycol (hereinafter referred to as PTMG).

[Conventional technology]

Conventionally, as a method for producing PTMG, a method is known in which PTMG is produced using a combination of inexpensive activated clay and acetic anhydride as a polymerization catalyst for tetrahydrofuran (hereinafter referred to as THF) (for example, U.S. Pat. No. 4, 243). , 799
issue). However, this method has a low polymerization yield. Therefore, the catalyst cost per amount of polymer obtained is high.

In particular, with this catalyst system, the polymerization yield and molecular weight of the polymer vary greatly depending on the moisture in THF, and there are isolated islands where only low-moisture THF L can be used, making it difficult to control the quality.

[Problem that the invention seeks to solve]

The present inventors have conducted intensive research on a method for producing PTMG that is not easily affected by water content in THF and can obtain stable quality PTMG at a high yield, and have finally arrived at the present invention.

[Means for solving problems]

The present invention is a method for producing PTMG, which is characterized by hydrolyzing a polymer obtained by 1) polymerization with THF in the presence of a catalyst containing hydrogen fluoride, a montmorillonite mineral, and acetic anhydride as essential components.

In this specification, parts and % are parts by weight and % by weight, respectively.
shows.

TI (F) used in the present invention can be used by ring-closing and dehydrating 1,4-butanediol by a known method.Also, unreacted THF recovered after polymerization can be purified by a known method.THF is not necessarily used. A commercially available product with a water content of 0.
There is no need to purify the THF to less than 0.3%, and approximately 1% water content in THF is tolerated.

Commercially available anhydrous hydrogen fluoride can be used as the hydrogen fluoride, and the montmorillonite mineral can be selected from those commercially available as activated clay and acid clay. For example, Galleon Earth NS.

Galleon Earth NC, Galleonite 136, and Galleonite 236C are all manufactured by Mizusawa Chemical Industry Company f! N), etc.

Commercially available acetic anhydride can be used.

The ratio of each catalyst component to THF is usually 0.05 to 10 parts of hydrogen fluoride to 100 parts of THF, preferably 0.
．． 1 to 5 parts, montmorillonite minerals usually 0.2 to 2 parts
0 parts, preferably 1 to 10 parts, acetic anhydride usually 0.
5 to 20 copies, and 1 to 15 copies for good people.

If the amount of hydrogen fluoride is less than 0.05 part, the effect of water in THF will be increased, the polymerization yield will decrease, and the quality of the polymer, such as the molecular weight, will vary. When the amount is more than 10 parts, the reaction becomes violent and undesirable side reactions such as fluorination reaction of the polymer occur.

If the content of the montmorillonite mineral is less than 0.2 part, the molecular weight of the polymer will vary widely, and the polymerization yield will also decrease.
Even if the amount is more than 0 parts, the polymerization yield will not increase, but on the contrary, the loss of adhesion of the polymer will increase and the amount of waste will increase.

Furthermore, if the amount of acetic anhydride is less than 0.65 parts, polymerization will not start, and if it is more than 20 parts, a series transfer reaction, which is a side reaction, will occur and the number average molecular weight will not increase.

Based on the total weight of hydrogen fluoride, montmorillonite mineral, and aqueous acetic acid, hydrogen fluoride is usually 2 to 60%, preferably 3 to 30%, and montmorillonite mineral is usually 4 to 9%.
0%, preferably 8-60%, acetic anhydride usually 5-95%
%, preferably 10 to 80%.

If any one of these three types of plowing medium is missing, the yield of the polymer will be extremely reduced, and in some cases, polymerization will hardly proceed. Even when a polymer can be obtained, it takes a long time to polymerize, and it is difficult to adjust the molecular weight of the polymer, making it difficult to stabilize the quality.

There is no need to particularly limit the usage of these three types of catalysts.

An example of the easiest method is to add the three catalysts separately to THF in any order, such as adding hydrogen fluoride and montmorillonite minerals in any order, and then adding aqueous acetic acid. be.

The humidity at which the catalyst is added to the THF is usually from 0 to 50°C, preferably from 0 to 40°C. If the temperature is lower than 0°C, the initiation of polymerization will be slow, while if it is higher than 50°C, undesirable side reactions such as coloring will occur.

Polymerization temperature is usually 10-50°C, preferably 20-40°C
It is. When the polymerization temperature is higher than 50°C, the apparent polymerization rate increases, but on the contrary, the polymerization yield decreases.In addition, chain transfer reactions not only make it difficult to adjust the molecular weight, but also cause a decrease in quality such as coloring. . At temperatures below 10°C, polymerization is slow and is disadvantageous for industrial production. The polymerization humidity can be adjusted by a conventional method, for example, by cooling the reactor using cooling water.

The polymerization time varies depending on the catalyst amount ratio and polymerization humidity, but is generally 3 to 10 hours, preferably 4 to 8 hours. If the polymerization time is shorter than 3 hours, the polymerization yield will be low, and if it is longer than 10 hours, this polymerization will be an equilibrium polymerization and will not lead to an improvement in the polymerization yield.

When a predetermined polymerization reaction is completed, alkaline water or the like is added to eliminate the catalyst activity and stop the polymerization. Next, the catalyst residue is separated and removed, and unreacted THF is distilled off and recovered.
of acetate is obtained. This PTMG acetate can be hydrolyzed into hydroxyl group-terminated PTMG. Hydrolysis may be carried out by a known method; for example, an aqueous solution of caustic soda is added to the polymer in an excess molar ratio, an appropriate solvent is added if necessary, and the mixture is stirred and mixed at 80 to 120°C for 2 to 5 hours. Subsequently, the oil component is separated, and the remaining water-excess alkali, salts, etc. are removed by distillation, adsorption, furnace separation, or other methods to obtain purified PTMG. The number average molecular weight of the obtained PTMG is usually 500 to 4000.
It is.

〔Example〕

The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto.

Example 1 and Comparative Example 1.2 THF (containing 0.5% water) 250 was placed in a sealable SUS reactor equipped with a stirrer, thermometer, and dropping funnel.
136°C, cooled to 10°C, and cooled to -5°C.
(manufactured by Mizusawa Chemical Industry) was added thereto, and the reactor was sealed. Subsequently, 30 parts of acetic anhydride was added dropwise with stirring from a dropping funnel connected to the reactor to initiate polymerization. After stirring for 4 hours while maintaining the temperature inside the reactor at 30° C., 70 parts of a 30% aqueous sodium hydroxide solution was added to stop the polymerization, and the aqueous layer containing catalyst residue was separated and removed. Next, hydrolysis was performed.

Hydrolysis was carried out using an autoclave, and the polymer solution was
18 parts of a 30% caustic soda aqueous solution was added to the temperature of 1.
The mixture was stirred at 10-120°C for 2 hours. After completion of the reaction, the alkaline aqueous solution was separated and removed by standing still, and unreacted THF was distilled off to obtain crude PTMG.

After that, in order to remove trace impurities such as alkaline content remaining in PTMG, a canned synthetic adsorbent [Neyoward 600 (manufactured by Kyowa Chemical Industry Co., Ltd.)] is added, and adsorption treatment and filtration are performed, resulting in purified PTMG. I got it. Example 1
For comparison, Table 1 shows the data of an experiment conducted under the same conditions as in Example 1, except that the water content of THF was changed and anhydrous hydrogen fluoride was not added.

Table 1 Example 2.3 and Comparative Example 3 Table 2 shows the data of an experiment conducted under the same conditions as Example 1, except that the amount of acetic anhydride, which is one component of the catalyst, was changed.

Table 2 Examples 4 to 6 and Comparative Example 4 Table 2 shows the data of experiments conducted under the same conditions as Example 1, except that the montmorillonite mineral, which is one of the components of the solvent, was changed.
Table-3 shown in Table 3 Note) Bitterness: As the montmorillonite mineral, Example 4 is Galleon Earth NS, and Examples C and 6 are Galleon Earth N.
C (manufactured by Mizusawa Chemical Industry Co., Ltd.) [Effects of the Invention] According to the method of the present invention, PTMG of stable quality can be obtained in high yield. Since THF as a raw material can be used even if it has a relatively high water content, the cost for purifying an azeotropic THF/water mixture can be reduced compared to the normal case, which is industrially advantageous.

The polymerization catalyst used is industrially available at low cost and has a high conversion rate from THF to PTMG.
TMG] The catalyst cost per unit of production is low, and the high conversion rate also improves the productivity of polymerization equipment, which can be said to be advantageous from an industrial perspective.

The PTMG obtained by the present invention is a urethane-neutral compound.

Claims (1)

[Claims] 1. A method for producing polytetramethylene ether glycol, which comprises hydrolyzing a polymer obtained by polymerizing tetrahydrofuran in the presence of a catalyst containing hydrogen fluoride, a montmorillonite mineral, and acetic anhydride as essential components.