JPH0116251B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polyether glycol, and more particularly to a method for producing polyether glycol having a relatively low molecular weight, high functionality, and high purity and having oxytetramethylene groups as a main component. Polyether obtained by polymerizing tetrahydrofuran or a mixture of tetrahydrofuran and other cyclic ethers copolymerizable with it in the presence of a ring-opening polymerization catalyst containing fuming sulfuric acid or fluorosulfuric acid as the main component, is hydrolyzed under acidic conditions. By doing so, polytetramethylene glycol (hereinafter referred to as
It is known to produce copolymerized polyether glycols (abbreviated as PTMG) and oxytetramethylene group-based copolymerized polyether glycols (hereinafter collectively referred to as PTMG-based polyether glycols, including PTMG) (for example, PTMG-based polyether glycol). −25438, 49−
28917, 45-3104). The PTMG thus obtained
When polyether glycols are used as raw materials for polyurethane, elastic polyester, elastic polyamide, etc., their industrial importance has been attracting attention in recent years because they provide materials with excellent physical properties such as mechanical properties and hydrolysis resistance. There is. Usually, in these applications, materials with a relatively high number average molecular weight of about 500 to 5000 are used, and in order to obtain materials with excellent properties, the degree of functionality must be close to 2, that is, the number average molecular weight must be close to 2. is a hydroxyl group, and PTMG polyether glycol is
It is very important that the terminal sulfate ester groups of polyether produced during polymerization and the acids produced during the hydrolysis treatment of the terminal sulfate ester groups of polyether are hardly contained. In some cases, it may cause decomposition reaction of PTMG polyether glycol, interfere with urethanization reaction or esterification reaction, or cause undesirable side reactions to produce polyurethane, elastic polyester or elastic polyamide. In some cases, a problem arises in that materials with excellent physical properties cannot be obtained. The method of producing PTMG-based polyether glycol using fuming sulfuric acid or fluorosulfuric acid as a ring-opening polymerization catalyst can easily produce the above-mentioned relatively low molecular weight polyether glycol, and the hydrolysis reaction can also be carried out under acidic conditions. This has the advantage that it progresses relatively quickly. However, in this method, since the hydrolysis reaction is an equilibrium reaction, a small amount of sulfuric ester group tends to remain at the end of the polyether, and the acid generated during the hydrolysis reaction has a high affinity with the polyether. It tends to remain as a free acid in polyether, and the obtained
There have been various problems when using PTMG polyether glycol as a raw material for polyurethane and the like. In order to reduce the amount of terminal sulfate ester groups in polyether, it is possible to reduce the sulfuric acid concentration during the hydrolysis reaction, but in this case, the amount of water for hydrolysis becomes extremely large, resulting in large-sized This requires a reactor, which is disadvantageous for industrial production, and a large amount of the produced PTMG polyether glycol dissolves into the water layer, reducing the recovery rate as a product and increasing the burden of wastewater treatment. .
Another method to reduce the amount of sulfate ester groups in polyether is to perform part of the hydrolysis under conditions with a relatively high sulfuric acid concentration, then remove the water layer and add water again to reduce the sulfuric acid concentration. This method continues hydrolysis under certain conditions. In this case, the size of the reactor can be small, but the loss of PTMG-based polyether glycol into the aqueous layer is still considerable, which is unacceptable in industrial practice, especially in the case of PTMG-based polyether glycols with molecular weights below 1000. This is an impossible range. On the other hand, the remaining free acid (hereinafter abbreviated as residual acid)
A common method for removing polyether is to hydrolyze the polyether, separate the aqueous layer, and wash the PTMG polyether glycol with water or an aqueous alkaline solution. However, even if you try to remove the residual acid content by washing with water, the small amount of residual acid content in PTMG polyether glycol is difficult to extract with water. In this case, it is necessary to increase the number of washings, which requires a lot of time and effort, and also increases the loss of PTMG polyether glycol into the aqueous layer, which also increases the burden of wastewater treatment. On the other hand, when cleaning with an aqueous alkali solution such as sodium hydroxide, sodium carbonate, sodium bicarbonate, or potassium carbonate, residual acids can be neutralized and removed reliably, but the system emulsifies during cleaning. However, after washing, it takes a very long time to separate the PTMG polyether glycol layer and the aqueous layer, or in some cases, it may not be possible to separate the layers at all. Even if the layers are separated over a long period of time, the separation may not be sufficient and a trace amount of alkali may be present.
Remains in PTMG polyether glycol. Even if the amount of this alkali is small, when PTMG polyether glycol is used as a raw material for polyurethane, it causes abnormal reactions such as gelation when reacting with diisocyanate.
Therefore, when cleaning with an alkaline aqueous solution,
After that, many times of washing with water is required, and the above-mentioned
Loss of PTMG polyether glycol becomes unavoidable. Another method for removing residual acid content is
There is a method of neutralizing and removing acid by bringing PTMG polyether glycol into contact with a solid alkali such as calcium hydroxide. However, this method works effectively only on the surface of the solid alkali, and therefore requires a large amount of solid alkali compared to the residual acid content to be removed, which is uneconomical. Furthermore, when solid alkali is used in suspension, it is difficult to operate because it deposits on pipe walls during transfer, while when solid alkali is used as a packed tower, it takes time to replace it, and it also prevents clogging. Because of this tendency, it is very difficult to implement it industrially. As mentioned above, all of the conventionally known methods for removing residual acid content are still far from being fully satisfactory from the standpoint of industrial implementation. Under such circumstances, the present inventors used a ring-opening polymerization catalyst containing fuming sulfuric acid and/or fluorosulfuric acid as a main component to produce a PTMG-based polyether glycol containing almost no residual sulfuric ester groups and residual acid content. As a result of various studies on the method, we were able to not only remove most of the residual sulfuric acid ester groups, but surprisingly also be able to significantly reduce the residual acid content with an extremely small number of washings.
Moreover, we discovered a method that minimizes the amount of PTMG polyether glycol dissolved in the water layer.
The present invention has been achieved. That is, the present invention comprises (A) polymerizing tetrahydrofuran or a mixture of tetrahydrofuran and other cyclic ether copolymerizable with it in the presence of a ring-opening polymerization catalyst containing fuming sulfuric acid and/or fluorosulfuric acid as a main component; (B) Add an alkaline aqueous solution to the polymerization reaction product and heat hydrolyze it under strongly acidic conditions, and then (C) add the polyether glycol, which is the hydrolysis reaction product, to a neutral sulfate aqueous solution or a basic magnesium salt aqueous solution. This is a method for producing polyether glycol, which is characterized by washing. In the method of the present invention, especially when washing with a neutral sulfate aqueous solution in step (C), it is possible to carry out the hydrolysis reaction of polyether, which is a polymerization reaction product, in a region where the sulfuric acid concentration in the aqueous layer is high. Therefore, the amount of liquid added during hydrolysis can be reduced, there is no need to use a large hydrolysis reactor, and losses due to dissolution of PTMG polyether glycol into the aqueous layer can be reduced. In addition, when using a basic magnesium salt in step (C), the basic magnesium salt can be added to the aqueous layer after hydrolysis and washed as is without extracting the aqueous layer, and the aqueous layer can be separated or washed. This eliminates the need to prepare a basic magnesium salt aqueous solution for cleaning. Regardless of which cleaning method is used in step (C), the amount of liquid can be reduced by increasing the concentration of the alkaline aqueous solution added during hydrolysis in step (B), and the amount of residual sulfate ester groups can be reduced. In addition, especially low molecular weight molecules below 1000
In the production of PTMG-based polyether glycol, loss due to dissolution in the aqueous layer can be suppressed to a small amount. Furthermore, residual acid content, which is difficult to extract with water, can be extracted very efficiently with these solutions, and the residual acid content can be reduced to nearly zero with a small number of washings.
Layer separation after treatment can also be carried out very easily, and it is possible to reduce the amount of PTMG polyether glycol dissolved in the aqueous layer during this treatment. The method of the present invention will be explained in detail below. In the method of the present invention, first, in step (A), tetrahydrofuran or a mixture of tetrahydrofuran and other cyclic ether copolymerizable with the same is added in the presence of a ring-opening polymerization catalyst containing fuming sulfuric acid and/or fluorosulfuric acid as a main component. Polymerize with Specific examples of cyclic ethers copolymerizable with tetrahydrofuran include ethylene oxide, propylene oxide, three-membered ring ethers such as epichlorohydrin, oxacyclobutane, 3,3-dimethyloxacyclobutane, and 3,3-bis(chloromethyl).
Four-membered ring ethers such as oxacyclobutane, 2-
Examples include five-membered ring ethers such as methyltetrahydrofuran, 3-methyltetrahydrofuran, and 2,5-dihydrofuran, tetrahydropyran, and oxacycloheptane. When obtaining a copolymerized polyether glycol containing an oxytetramethylene group as a main component, the amount of the cyclic ether copolymerizable with tetrahydrofuran used is usually 100 parts by weight or less, preferably 50 parts by weight, based on 100 parts by weight of tetrahydrofuran. Parts by weight or less. Fuming sulfuric acid used as a ring-opening polymerization catalyst is usually
Suitably, the free SO ₃ concentration used in the production of PTMG-based polyether glycols is about 40% by weight or less, preferably 20% to 35% by weight. Although fuming sulfuric acid can be used alone,
If necessary, a suitable second component may be present in order to increase the polymerization rate or control the molecular weight. The second component is perchloric acid, perchlorate,
Metal fluorides, metal borofluorides, aromatic compounds, etc. can be used, but metal borofluorides, particularly sodium borofluoride or potassium borofluoride, are preferred from the viewpoint of ease of acquisition and handling, and effectiveness. The amount of ring-opening polymerization catalyst used is not particularly limited. To give an example of the range usually used, in the case of fuming sulfuric acid, 10 to 40 parts by weight per 100 parts by weight of the monomer, and when using with the addition of a second component, 100 parts by weight of oleum. Use 0.05 parts by weight to 20 parts by weight. In the case of fluorosulfuric acid, the amount used is 1 to 20 parts by weight per 100 parts by weight of the monomer. The amount of these ring-opening polymerization catalysts to be used is appropriately selected depending on the required molecular weight of the PTMG polyether glycol. The polymerization temperature is not limited as long as it is below the ceiling temperature for polymerization of tetrahydrofuran, but the temperature range usually used is -30°C to 40°C. It is also possible to conduct the polymerization at a low temperature of 0° C. or lower for a predetermined period of time and then raise the temperature to 10° C. or higher to continue the reaction. This polymerization method is advantageous because it can improve the catalyst efficiency. The polymerization reaction method is not particularly limited, and various methods such as batch reaction and continuous reaction can be used. When conducting a batch reaction, in order to facilitate the removal of the heat of mixing, methods such as continuously adding catalyst to the monomers at an appropriate rate and stirring the polymerization system to remove heat are used. It is preferable. Furthermore, in a continuous reaction, it is advantageous to mix a monomer such as tetrahydrofuran and a ring-opening polymerization catalyst at a low temperature and supply the mixture to the reactor while removing heat. Although the polymerization reaction can be carried out in the presence of an inert solvent such as cyclohexane, dichloroethane, dichloromethane, etc., it is preferable to carry out the polymerization without using a solvent unless particularly necessary. Further, the polymerization is preferably carried out in an atmosphere of an inert gas such as helium, nitrogen, or argon. Next, in step (B), an alkaline aqueous solution is added to the reaction product obtained by polymerization, and the mixture is heated under strong acidity to perform a hydrolysis treatment. The amount of alkaline aqueous solution added at this time is such that the sulfuric acid concentration in the aqueous layer after treatment is 5.
It is preferable to select the amount within the range of ~40% by weight. When the sulfuric acid concentration exceeds 40% by weight, the equilibrium conversion rate of the hydrolysis reaction decreases and the amount of residual sulfate ester groups tends to increase; on the other hand, when the sulfuric acid concentration exceeds 5% by weight
If it is less than 20%, the rate of hydrolysis reaction decreases and the treatment takes a long time, and a large amount of water is required, which is not preferable. The sulfuric acid concentration in the aqueous layer after treatment is determined by the amount of oleum and/or fluorosulfuric acid used in polymerization and water, since most of the sulfuric ester groups at the terminals of polyether are hydrolyzed to sulfuric acid during treatment. The amount of sulfuric acid produced is substantially the same as the amount of sulfuric acid produced by the reaction with [the following formulas (1) and (2)], so calculate the amount of sulfuric acid produced and subtract the amount neutralized by the alkali. All you have to do is calculate the amount of sulfuric acid used. H ₂ SO ₄・xSO ₃ +H ₂ O→(1+x)H ₂ SO ₄ (1) FSO ₃ H＋H ₂ O→H ₂ SO ₄ +HF (2) Hydrolysis treatment is performed by adding only water to the polymerization reaction product. However, when using a ring-opening polymerization catalyst containing fuming sulfuric acid as the main component,
In the production of PTMG-based polyether glycol, a large amount of fuming sulfuric acid is used, so if only water is added, a considerable amount of water is required, so adding alkali to neutralize some of the sulfuric acid reduces the amount of added liquid. This is advantageous because it requires less amount and at the same time can reduce the amount of PTMG polyether glycol dissolved in the aqueous layer. The alkalis used in this case include alkali metal and alkaline earth metal hydroxides, oxides, and ammonia.
Alkali metal hydroxides and oxides are preferred.
The amount of alkali used is 1/4 or more of the amount required to neutralize the amount of oleum and/or fluorosulfuric acid used in polymerization, and the pH of the hydrolysis reaction system is 3 or less, preferably 1 or less. The appropriate amount is suitable for The alkali may be added in its entirety prior to the hydrolysis treatment, or may be added stepwise or continuously during the hydrolysis treatment. The hydrolysis treatment temperature is not particularly limited, but preferably 50°C or higher, particularly 50 to 150°C. If the treatment temperature is less than 50° C., the rate of hydrolysis reaction will be slow and the treatment time will be longer, and in addition, in the production of PTMG polyether glycol having a molecular weight of about 2000 or more, it will be difficult to separate the layers after treatment. On the other hand, if the processing temperature exceeds 150°C, decomposition and deterioration of the PTMG polyether glycol during processing are likely to occur.
Furthermore, the corrosive effects of sulfuric acid or hydrogen fluoride become stronger, and extremely expensive acid-resistant materials are required for the hydrolysis reactor. A particularly preferred hydrolysis treatment temperature is 60 to 120°C. The hydrolysis treatment temperature may be kept constant throughout the treatment, or the temperature may be raised or lowered stepwise or continuously with the treatment time. The hydrolysis treatment time varies depending on the treatment temperature, sulfuric acid concentration, or molecular weight of the PTMG polyether glycol and is not particularly limited, but under the above conditions it is usually 1 to 10 hours. The method of carrying out the hydrolysis treatment is also not particularly limited, and either a batch method or a continuous method is possible. Further, in these hydrolysis treatments, the polymerization reaction product and the aqueous solution phase separate and the system becomes non-uniform, so it is preferable to stir the system by an appropriate method during the treatment. This hydrolysis process converts the terminal sulfate ester groups of polyether into hydroxyl groups, but in order to minimize the amount of PTMG-based polyether glycol dissolved or emulsified in the cleaning solution in the next step (C), it is necessary to It is preferable that the amount of sulfate ester groups is 100 ppm or less based on the weight of PTMG polyether glycol as an SO ₄ equivalent value, and furthermore, in order to shorten the time for layer separation between the PTMG polyether glycol layer and the aqueous layer after washing. for
It is preferably 20 ppm or less. Preferred hydrolysis methods for suppressing the amount of residual sulfate ester groups in PTMG polyether glycol include the following method. First, water was added to the polymerization reaction product under the same conditions as in the previous example, and after some hydrolysis while heating and stirring, 90% of the sulfuric acid was
In this method, sodium hydroxide or an aqueous solution thereof is added in an amount necessary to neutralize the content, and the mixture is heated and stirred under the same conditions. Furthermore, the second method is to add water corresponding to a sulfuric acid concentration of 50% or less to the polymerization reaction product, and then heat and stir the system at a temperature of 60°C to 120°C to partially hydrolyze the sulfuric acid. of 80
% to 95% of aqueous sodium hydroxide solution is continuously added for 1 to 3 hours,
After the addition is complete, the hydrolysis may be completed by further heating and stirring for 1 to 5 hours. In addition to these examples, various other hydrolysis methods can be used. Prior to these hydrolysis treatments, adding an antioxidant such as a phenolic or amine type antioxidant can prevent coloring when the resulting PTMG polyether glycol is reacted with diisocyanate to form polyurethane. . The polymerization reaction product contains unreacted monomers, which may be recovered by a method such as distillation prior to the hydrolysis treatment, but preferably by distillation during the above treatment. Usually, after the above-mentioned hydrolysis treatment is carried out, the aqueous layer and the PTMG polyether glycol layer are separated by means such as standing still or centrifugation, and the aqueous layer is extracted. The temperature for layer separation is not particularly limited, but a high temperature is better in terms of ease of layer separation and solubility of PTMG polyether glycol in the aqueous layer. It is particularly suitable to carry out. However, when a basic magnesium salt is used in the next step (C) as described above, the basic magnesium salt can be added to the aqueous layer and washed as is without removing the aqueous layer after the hydrolysis treatment. In step (C), the obtained PTMG polyether glycol, which is a hydrolysis reaction product, is washed with a neutral sulfate aqueous solution or a basic magnesium salt aqueous solution. When using a neutral sulfate aqueous solution as a cleaning liquid, the neutral sulfate can be used as long as the aqueous solution is neutral and the solubility in water at the sulfur treatment temperature is 5% by weight or more. However, sodium sulfate, potassium sulfate, or magnesium sulfate is preferred from the viewpoint of availability, price, and wastewater quality. The amount of the sulfate aqueous solution to be used is not particularly limited, but in order to perform the treatment efficiently, it should be in the range of 20 to 200 parts by weight as the sulfate aqueous solution per 100 parts by weight of PTMG polyether glycol. preferable. The sulfate aqueous solution to be used can be newly prepared and used, but the aqueous layer extracted after the hydrolysis treatment in step (B) or a part of it can be neutralized with an alkali to accurately reduce the concentration. It is also possible to adjust and use it. It is convenient to use an alkali that produces water-soluble neutral sulfate as the alkali added during the hydrolysis treatment, and to neutralize the extracted aqueous layer using the same alkali. The washing treatment with a neutral sulfate aqueous solution is preferably carried out by heating the system to a temperature of 50° C. or higher. If the cleaning treatment temperature is lower than 50℃, especially when manufacturing PTMG polyether glycol with a molecular weight of about 2000 or more, it will be difficult to separate the layers after treatment, and the amount of residual sulfate groups and residual acids will decrease. It becomes difficult to do. (B) From the viewpoint of equipment corrosion and processing pressure as described in the process explanation, processing is carried out at 150°C.
Below, the temperature is particularly preferably 120°C or lower. The cleaning treatment temperature may be constant during the treatment or may be changed during the treatment. The cleaning treatment time is not particularly limited and can be arbitrarily selected depending on conditions such as treatment temperature, but usually about 0.5 to 5 hours is sufficient. Various cleaning methods can be used, such as batchwise and continuous methods, and various types of processing equipment can be used accordingly, but in any method, the system must be agitated using an appropriate method. is preferred. The amount of residual sulfate ester groups and residual acid can be extremely reduced by a single cleaning treatment with a neutral sulfate aqueous solution, but if necessary, two or more treatments with a neutral sulfate aqueous solution can be performed. By doing so, it is possible to reduce the amount of residual sulfuric ester groups and residual acids to almost zero. When carrying out such a multi-stage cleaning treatment, in the case of a batch-type treatment, the aqueous layer separated after the treatment can be accurately neutralized to neutrality with an alkali and then used as the treatment liquid for the next stage. Furthermore, in the case of continuous cleaning treatment, the aqueous layer separated after treatment may be supplied as is as a treatment liquid to the previous stage, thereby performing a so-called countercurrent contact type treatment. Furthermore, by accurately neutralizing the aqueous layer extracted from the first stage with alkali to neutrality, adjusting the concentration and amount, and supplying it as the last stage treatment liquid, most of the treatment liquid can be recycled and used. Can be done. By adopting these methods, the amount of neutral sulfate used in batch or continuous cleaning treatment can be significantly reduced. In addition to this, various methods of implementing the cleaning process are possible. In addition, when using a basic magnesium salt aqueous solution, examples of the basic magnesium salt include magnesium hydroxide, magnesium oxide, magnesium carbonate,
Examples include basic magnesium carbonate and mixtures thereof. These basic magnesium salts generally have a relatively low solubility in water, so when adding a small amount, they can be used in the form of an aqueous solution, but when adding a large amount, they can be used in a suspended state. good. Furthermore, when magnesium salts such as magnesium carbonate and basic magnesium carbonate are dissolved in water, the solubility can be considerably increased by blowing carbon dioxide gas, and the solution prepared in this way is preferably used in the method of the present invention. can be used. The basic magnesium salt may be dissolved or suspended in water alone, but in order to avoid loss due to dissolution of the PTMG polyether glycol in the aqueous layer, especially in the production of low molecular weight PTMG polyether glycol. It is also possible to use it by dissolving or suspending it in an aqueous solution of a suitable neutral salt. Although various types of neutral salts can be used in this case, the above-mentioned neutral sulfates are particularly preferred. When using basic magnesium salts, use unwashed
Of course, it is also possible to add water or a neutral salt aqueous solution to the PTMG polyether glycol, and then add the solid basic magnesium salt. The amount of basic magnesium salt used is preferably in excess of the amount of residual acid in the system so that the pH of the system is always 7 or higher. If the amount of basic magnesium salt used is too small and the pH of the system becomes less than 7 during the cleaning process, it will be difficult to remove the residual acid content reliably. Washing treatment with a basic magnesium salt aqueous solution is carried out by separating the layers of the system after hydrolysis treatment, extracting the aqueous layer, and then adding water or a neutral salt aqueous solution containing a basic magnesium salt to the PTMG polyether glycol layer. However, in a preferred embodiment, an excess of basic magnesium salt is added directly after the hydrolysis treatment without drawing out the aqueous layer, and
Cleaning is performed by setting the pH of the system to 7 or higher. In this case, the aqueous layer immediately after the hydrolysis treatment contains a relatively large amount of residual acid, but it is not necessarily necessary to neutralize the entire amount of residual acid with a basic magnesium salt; Basicity in an amount such that the PH of the system becomes 7 or more after being neutralized with another alkali such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, etc. within a range where the PH of the layer does not reach 7. Magnesium salts may be added. Of course, it is also possible to use a basic magnesium salt as an alkali during the hydrolysis treatment. By adopting such a method, neutral sulfate can be present in the aqueous layer, and especially low molecular weight sulfate can be present in the aqueous layer.
In the production of PTMG-based polyether glycol, it is advantageous because losses due to dissolution in the aqueous layer can be significantly reduced. The basic magnesium salt may be used in large excess, but in this case, since the basic magnesium salt has low solubility, a portion remains insoluble, making the operation somewhat difficult. However, even in such a case, the remaining solid basic magnesium salt can be easily separated from the PTMG-based polyether glycol by a method such as filtration. When performing the cleaning treatment, the amount of water or neutral salt aqueous solution containing a basic magnesium salt is not particularly limited, but is usually 10 to 500 parts by weight per 100 parts by weight of PTMG polyether glycol.
Preferably 20 to 200 parts by weight are used. The treatment temperature, treatment time, treatment method, etc. when using a basic magnesium salt aqueous solution are the same as when using a neutral sulfate aqueous solution. After performing the above washing treatment, the aqueous layer and the PTMG polyether glycol layer are separated by a method such as standing still or centrifugation, and the aqueous layer is extracted. In this case, it is preferable to perform the separation at a high temperature, as in the case of step (B). Since the PTMG polyether glycol thus obtained contains a considerable amount of water, water and other volatile components are removed by heating under normal pressure or reduced pressure. Various devices can be used for this purpose, such as a rotary evaporator and a thin film evaporator. In order to facilitate the removal of water, it is also possible to add a small amount of a low boiling point solvent that is azeotropic with water and perform evaporation and drying. From the viewpoint of preventing decomposition and deterioration of the PTMG polyether glycol at high temperatures, it is preferable to remove volatile components under reduced pressure. The obtained PTMG polyether glycol can be used as it is as a raw material for polyurethane, etc., but it is preferably used as a product after removing solid impurities using a suitable filter. By performing filtration after completely removing water and volatile components, neutral sulfate or basic magnesium can be added to PTMG-based polyether glycol even if the layer separation after washing is incomplete. It is possible to prevent salt contamination.
Reduces the viscosity of PTMG polyether glycol,
In order to facilitate the filtration, the filtration is preferably carried out at a high temperature of about 60°C to 120°C. The PTMG polyether glycol obtained by the method of the present invention contains almost no residual sulfuric ester groups or residual acids, has good productivity, high purity, and high quality, so it can be used as a raw material for polyurethane, elastic polyester, elastic polyamide, etc. suitable for rolls,
It is particularly useful in application fields that require extremely high performance, such as belts and solid tires, and its industrial value is extremely large. The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to these Examples unless the gist thereof is exceeded.
In the following examples, all number average molecular weights were measured using a vapor pressure osmometer, and the hydroxyl value (mg of KOH equivalent to OH groups in 1 g of polymer) was measured using a vapor pressure osmometer.
(number) and acid value are values analyzed according to the method of JIS-K1557-1970. Example 1 A four-necked separable flask with an inner volume of 2 and equipped with a glass stirrer, a dropping funnel, a thermometer, and a three-way pot was vacuum-dried and then added dropwise to 600 g of tetrahydrofuran kept at -10°C under stirring. Contains 0.9g of sodium borofluoride from funnel
Add 126 g of 25% oleum over 40 minutes. After the dropwise addition was completed, the reaction was carried out at -10℃ for 1 hour, and then the internal temperature was lowered to 30℃.
The temperature was raised to ℃ and the reaction was continued for another 2 hours, and 10 g of water was added to stop the polymerization. The conversion rate was 60%.
Next, 530 g of water (sulfuric acid concentration approximately 20%) was added, the dropping funnel was replaced with a distillation device, and unreacted tetrahydrofuran was distilled in an 80°C oil bath for hydrolysis treatment by heating for 1 hour, and then the concentration was 48% by weight. 204g of sodium hydroxide aqueous solution (equivalent to 90% neutralization rate)
was added continuously over an hour, and the internal temperature was lowered.
Raise the temperature to 100℃ and continue hydrolysis. 100℃ after addition
Heat for 2 hours. During these operations, unreacted tetrahydrofuran is distilled and recovered. 100℃
After heat treatment for 4 hours at
The PTMG layer is washed using 350 g of 20% sodium sulfate solution and heated at 80° C. for 1 hour. After separating and extracting the aqueous layer, volatile components are removed in the same manner as in each of the above examples, and the mixture is passed through a membrane filter with a pore size of 10 μm to obtain PTMG. The analysis results of PTMG thus obtained were as shown in Table 1. Example 2 Using the same reaction apparatus as in Example 1, 120 g of 25% oleum was added dropwise to 600 g of tetrahydrofuran kept at -20°C over 40 minutes from a dropping funnel with stirring, and after the addition was completed, the mixture was heated at -20°C. Let it react for 2 hours. Next, the internal temperature was raised to 10°C and the reaction was continued for an additional 2 hours, after which 10 g of water was added to stop the polymerization. The final conversion rate was 57%. Next, the dropping funnel was replaced with a distillation device, and while stirring the contents vigorously, a solution of 52 g of sodium hydroxide dissolved in 250 g of water (neutralization rate of 50%, equivalent to 20% sulfuric acid concentration after treatment) was added and mixed. Thereafter, the mixture is heated in an oil bath at 80° C. for 2 hours to perform a hydrolysis treatment and to recover unreacted tetrahydrofuran. Leave to stand in the same manner as in Example 1,
After layer separation, the aqueous layer was removed, and the PTMG layer was heated at 120°C using 300 g of 15% sodium sulfate solution.
A two-hour heat washing treatment is performed twice, and unreacted tetrahydrofuran remaining during the first treatment is recovered. Thereafter, it was treated in the same manner as in Example 1, and finally passed through a membrane filter with a pore size of 10 μm. The analysis results of PTMG were as shown in Table 1. Example 3 In the experiment of Example 2, the amount of 25% oleum was
The amount was 180 g and the dropping time was 1 hour. Immediately after the dropwise addition was completed, the internal temperature was raised to 30°C and the reaction was continued for another 1 hour. After stopping the polymerization with 130 g of water, the conversion rate was measured and found to be 52%. After replacing the dropping funnel with a distillation device, 101g of sodium hydroxide
A solution prepared by dissolving 130 g of water in 130 g of water was added continuously over a period of 1 hour, and heated in an oil bath at 80°C, and after the addition was completed, the mixture was further heated at 80°C for 1 hour for hydrolysis treatment. During this time, unreacted tetrahydrofuran is simultaneously distilled and recovered. Next, a solution of 23 g of sodium hydroxide dissolved in 25 g of water was added continuously over a period of 1 hour, and the temperature of the oil bath was raised to 100° C. to perform a heating hydrolysis treatment while recovering unreacted tetrahydrofuran. After the treatment, the mixture is allowed to stand at 100°C to separate the layers, and about 90% of the aqueous layer is extracted. After that, 150g of 20% sodium sulfate solution is added and the mixture is heated and washed at 100°C for 2 hours. Remove the aqueous layer in the same manner as in each of the above examples,
PTMG layer again with 150 g of 20% sodium sulfate solution.
After heating and cleaning at 80℃ for 30 minutes using
Repeat the same operation once again. The analysis results of PTMG obtained by carrying out the same operation as in Example 2 were as shown in Table 1. Example 4 The same experiment as in Example 2 was carried out until the aqueous layer was separated by adding sodium hydroxide solution and heating and hydrolyzing at 80°C. Neutralize using 10% aqueous sodium hydroxide solution until . Furthermore, 1% sodium carbonate aqueous solution was added until the pH reached 7, and then water was added to adjust the sodium sulfate concentration of the solution to 15%, and 300 g each of the obtained solution was used in place of the sodium sulfate aqueous solution. As a result of carrying out the same washing operation as in Example 2, the analysis results of PTMG obtained were as shown in Table 1. Example 5 In the experiment of Example 2, the aqueous layer extracted after the first washing treatment with an aqueous sodium sulfate solution was neutralized with a 1% aqueous sodium carbonate solution until the pH of the solution reached 7. aqueous solution
In addition to the PTMG layer, the same washing treatment operation was performed, and the obtained PTMG analysis results were as shown in Table 1. Example 6 The experiment of Example 1 was repeated using 300 g of 20% magnesium sulfate aqueous solution instead of the sodium sulfate aqueous solution, and the analysis results of PTMG obtained were as shown in Table 1.

[Table] Comparative Example 1 In the experiment of Example 2, PTMG was
I took out the layer and tried to remove the volatiles at 80°C under reduced pressure using a rotary evaporator, but
Polymer decomposition occurred and dry PTMG could not be obtained. Table 2 shows the results of measuring the amount of sulfuric ester, amount of residual acid, and acid value of the PTMG layer itself taken out. Comparing these results with the results of Example 4 in Table 1, it is clear that these amounts are significantly reduced by washing with a neutral sulfate aqueous solution. Comparative Example 2 After conducting an experiment under the same conditions as in Example 2 up to the hydrolysis treatment with a sodium hydroxide solution,
Add 350g of 15% sodium carbonate aqueous solution to the PTMG layer obtained by separating the aqueous layer, and heat at 120℃ for 2 hours with stirring.
When heated for a period of time and washed, the contents became emulsified and did not readily separate into layers. After the contents were allowed to stand for several days, they were further centrifuged, the separated aqueous layer was extracted, 350 g of water was added, and the mixture was stirred at 100° C. for 2 hours for washing. At this time as well, the contents will be in an emulsified state, so let them stand for several days as before, then centrifuge them and remove the separated aqueous layer. The cloudy PTMG layer thus obtained is taken out, the volatile components are removed using a rotary evaporator, and the layer is passed through a membrane filter with a pore size of 10 μm. The analysis results of the obtained PTMG are shown in Table 2. This result shows that although the residual acid content can be removed by alkaline washing, the sulfuric acid ester group is hardly reduced. This PTMG also showed alkalinity, and when it and excess tolylene diisocyanate (NCO/OH molar ratio of about 2) were heated at 80°C, gelation occurred. Comparative Example 3 Under the same conditions as Example 2, the PTMG layer was heated and hydrolyzed with a sodium hydroxide solution, and the aqueous layer was separated.
Table 3 shows the relationship between the number of treatments and the acid value of PTMG when the heating cleaning treatment was repeated for 30 minutes at °C.
Furthermore, Table 2 shows the analysis results of PTMG obtained by drying and filtering the PTMG layer after washing six times under reduced pressure. These results show that when washing with water alone, the amount of sulfate ester groups decreases, but the residual acid content remains at a fairly high value even if the treatment is repeated. Comparative Example 4 The experiment of Example 2 was repeated using 300 g of a 15% aqueous solution of sodium hydrogen sulfate instead of the sodium sulfate solution, but due to the high residual acid content in the PTMG layer, PTMG decomposed during vacuum drying. I woke up. The analysis results for the PTMG layer before drying were as shown in Table 2.

【table】

[Table] Example 7 Using the same reaction apparatus as in Example 1, 100 g of 25% oleum was added dropwise over 40 minutes to 500 g of tetrahydrofuran cooled to -20°C. After the addition, 440g of water was added to the polymerization reaction product obtained by adding 10g of water after 2 hours at -20℃, then raising the temperature to 10℃ for 2 hours, and placing it in an oil bath at 80℃. under stirring at 1
A heating hydrolysis treatment is performed for a period of time, and unreacted tetrahydrofuran is recovered. Next, set the temperature of the oil bath to 100
℃ and aqueous sodium hydroxide solution with a concentration of 48%.
Add 170g continuously over 1 hour, then add 100g
After continuing to stir at ℃ for 2 hours to perform hydrolysis treatment and simultaneously collect unreacted tetrahydrofuran,
Leave at 100℃ to separate the layers. A portion of the separated PTMG layer was analyzed for residual sulfate group content and acid value, which were found to be 3 ppm or less and 0.25.
Next, without removing the aqueous layer, 5.4 g of solid basic magnesium carbonate was added to the system and slowly stirred. Most of the solids were dissolved in the aqueous layer, and the pH of the system was 8. Subsequently, the mixture was washed by heating and stirring in an oil bath at 80°C for 2 hours, and then allowed to stand at 80°C to separate the layers. Throughout these treatments, the pH of the system was approximately 8, and there was no difficulty in emulsifying the system or separating the layers, and the PTMG layer after separation was almost transparent.
The volatile matter was completely removed from this PTMG layer at 80° C. under reduced pressure using a rotary evaporator, and the PTMG was analyzed through a membrane filter with a pore size of 10 μm. The results of analysis of PTMG were as shown in Table 4. Example 8 The same experiment as in Example 7 was carried out up to the hydrolysis treatment, and then 21 g of a 20% aqueous sodium hydroxide solution was added without removing the aqueous layer, and the mixture was heated in an oil bath at 80°C for about 20 minutes. Heat and stir for a minute. The pH of the system at this time was approximately 5. Next, 1.5 g of a basic magnesium carbonate suspension aqueous solution having a concentration of 15% was added, and the mixture was washed by heating and stirring at 80° C. for 1 hour, and then allowed to stand still to separate the layers. The pH of the system was approximately 8 throughout the treatment, and there was no emulsification of the system and layer separation was easy, and the PTMG layer after separation was almost transparent. Furthermore, the analysis results of PTMG obtained by treatment in the same manner as in Example 7 were as shown in Table 4. Example 9 In the same manner as in Example 7, a solution of 1.5 g of sodium borofluoride dissolved in 55 g of 25% oleum was added dropwise to 500 g of tetrahydrofuran cooled to -10°C over 30 minutes, and then further heated at -10°C. 1 hour,
Subsequently, the temperature was raised to 20°C and the mixture was allowed to react for 2 hours. The conversion rate determined by gas chromatography was 61%. Next, 520 g of water was added to the polymerization reaction product, and the
Distill unreacted tetrahydrofuran in an oil bath at °C.
After heating and stirring for 2 hours while recovering, the temperature of the oil bath was raised to 100°C, and 50 g of 48% sodium hydroxide solution was continuously added over 1 hour for hydrolysis treatment. Continue to collect unreacted tetrahydrofuran during the addition, and immediately reduce the system to 100% after the addition is complete.
Leave to stand at ℃, separate the layers, and remove the aqueous layer. What remained
Add 250 g of water and a portion of the extracted water layer to the PTMG layer to adjust the sulfuric acid concentration in the water layer to approximately 1%, and then heat and stir in an oil bath at 100°C for 2 hours. After hydrolysis is completed, the mixture is allowed to stand at 100°C to separate the layers. A portion of the separated PTMG layer was analyzed for residual sulfate group content and acid value, which were found to be 4 ppm and 0.27. Next, without drawing out the aqueous layer, 9.7 g of 20% sodium hydroxide solution.
After heating and stirring for about 15 minutes in an 80℃ oil bath, 1.3g of basic magnesium carbonate suspension water with a concentration of 15% was added to bring the pH of the system to about 8, and the mixture was heated in an 80℃ oil bath for about 2 hours. Washing treatment is performed by heating and stirring for a period of time, and the mixture is allowed to stand still to separate the layers. There is no emulsification phenomenon in the system throughout the process, and layer separation is easy.
The PTMG layer was only slightly cloudy.
After removing the aqueous layer, the PTMG layer was treated in the same manner as in Example 7, and the analysis results of PTMG were as shown in Table 4. Example 10 Tetrahydrofuran 500 was prepared in the same manner as in Example 7.
70 g of fluorosulfuric acid was added to the solution at 20°C over 30 minutes, and the mixture was further reacted at 20°C for 5 hours. Conversion rate 71%. Next, add 350 ml of water to the resulting polymerization reaction product.
g and 56 g of a 45% aqueous sodium hydroxide solution were added thereto, and the mixture was heated for 2 hours with stirring in an oil bath at 95° C. while distilling and recovering unreacted tetrahydrofuran for hydrolysis treatment. The system was allowed to stand at 95°C to separate the layers, and the aqueous layer was extracted. 250g of a 10% aqueous sodium sulfate solution and 5g of concentrated sulfuric acid were added to the PTMG layer, and the mixture was heated at 100°C.
The mixture is heated for 2 hours with stirring in an oil bath for washing treatment, and unreacted tetrahydrofuran is recovered.
After the treatment, the mixture was allowed to stand at 100°C to separate the layers, and without removing the aqueous layer, 5.1 g of solid basic magnesium carbonate was added, and the mixture was heated and stirred for 2 hours in an 80°C oil bath for washing. Afterwards, let it stand at 80℃, separate the layers, and extract the aqueous layer. Throughout the treatment, the pH of the system was approximately 8, no emulsification of the system was observed, and layer separation was easy. The PTMG layer thus obtained was treated in the same manner as in Example 7, and the analysis results of PTMG were as shown in Table 4.

[Table] Comparative Example 5 0.074% sodium hydroxide solution instead of magnesium sulfate aqueous solution containing basic magnesium carbonate
The same experiment as in Example 7 was repeated using 300 g. During the washing process at 100°C, the system gradually became emulsified, and it took an extremely long time to let it stand and separate the layers after the process.
The PTMG layer remained in an emulsified state. Comparative Example 6 Using 300 g of water containing 0.21 g of calcium hydroxide instead of water containing basic magnesium carbonate,
The same experiment as in Example 7 was conducted. During the washing process, the system became emulsified, making it impossible to separate the layers at all after the washing process.

Claims (1)

[Claims] 1 (A) Tetrahydrofuran or a mixture of tetrahydrofuran and other cyclic ether copolymerizable with it is polymerized in the presence of a ring-opening polymerization catalyst containing fuming sulfuric acid and/or fluorosulfuric acid as a main component, and then (B) Add an alkaline aqueous solution to the polymerization reaction product, heat and hydrolyze it under strongly acidic conditions, and (C) wash the polyether glycol, which is the hydrolysis reaction product, with a neutral sulfate aqueous solution or a basic magnesium salt aqueous solution. A method for producing polyether glycol, characterized by: