JP7357535B2 - Method for producing alkylene oxide polymer - Google Patents

Description

The present invention relates to a method for producing alkylene oxide polymers (sometimes referred to as polyether polyols or polyalkylene glycols) such as polyethylene glycol. More specifically, the present invention relates to a method for producing the polymer, which is characterized by increasing the production efficiency of the polymer.

Alkylene oxide polymers are produced, for example, by polymerizing alkylene oxide compounds such as ethylene oxide and propylene oxide using an initiator having active hydrogen. Further, alkylene oxide polymers are typically used as soft segment components of polyurethane elastomers, so-called CASE materials such as adhesives, paints, and sealants.

Polymerization methods for producing high molecular weight polymers and copolymers, such as alkylene oxide compounds, have been developed for a long time and a large body of literature exists. Typical alkylene oxide polymerization methods include a wide range of metal atom-based methods including oxides and/or hydroxides of transition metals such as iron and metals such as magnesium, aluminum, zinc and calcium. There are methods of polymerization using a wide variety of catalysts. For example, US Pat. No. 2,971,988 (Patent Document 1) discloses a method using a calcium-based catalyst. Methods using zinc-based catalysts include Japanese Patent Publication No. 45-7751 (Patent Document 2), Japanese Patent Publication No. 53-27319 (Patent Document 3), European Patent No. 239,973 (Patent Document 4), and U.S. Pat. There is a method disclosed in Publication No. 4,667,013 (Patent Document 5). Further, WO 99/51610 (Patent Document 6) discloses a polymerization method utilizing a micelle state.

Furthermore, even now, methods for producing alkylene oxide polymers with high polymerization rates are being continuously developed.

U.S. Patent No. 2,971,988 Special Publication No. 45-7751 Special Publication No. 53-27319 European Patent No. 239,973 U.S. Patent No. 4,667,013 International Publication No. 99/51610

Toshiyo Tomita, Hiroyuki Funahashi, Bulletin of Suzuka Junior College, Vol. 12, pp. 73-78, 1992.

Conventionally, alkylene oxide polymers are produced by continuous polymerization methods or batch polymerization methods. In the process of determining conditions in these polymerization methods, it is important from the viewpoint of molecular weight control to quickly grasp the molecular weight at an intermediate stage. In particular, its importance tends to increase as the polymerization rate increases.
From the viewpoint of accuracy in molecular weight measurement, gel permeation chromatography (GPC) is superior. However, the GPC method requires the combination of many devices, and the measurement time including preparation of the measurement sample is relatively long. Further, as another method, a method using solution viscosity as an index of molecular weight has been used for a long time, and is a method that can be measured in a relatively short time. However, in the case of polymers in the low molecular weight range, this method may not have sufficient accuracy because differences in viscosity are difficult to appear.

In the case of alkylene oxide polymers, it is known that in an aqueous solution containing an electrolyte such as a saline solution, the alkylene oxide polymer exhibits a so-called cloud point, which is the temperature at which the alkylene oxide polymer changes from a hydrated state to a free state (Non-patent Document 1 ). Non-Patent Document 1 also discloses that the cloud point changes depending on the molecular weight of polyethylene glycol (PEG), the molar concentration of the electrolyte (NaCl), and the types of electrolyte cations and anions. The main purpose of Non-Patent Document 1 is to verify whether adding an electrolyte (dye) to an aqueous solution of PEG can serve as a substitute for a nonionic surfactant used as a dyeing aid. It has been shown that polypropylene glycol similarly develops a cloud point.
The method for measuring cloud point is a simple method and measurement results can be obtained in a relatively short time. Therefore, if molecular weight can be determined by cloud point measurement, it is considered to be very useful for the production process of alkylene oxide polymers.
It is known that an aqueous solution of an alkylene oxide polymer having a terminal-capped structure with a hydrocarbon group exhibits a cloud point at a relatively low temperature, and that there is a relatively linear relationship between the cloud point and the molecular weight.

On the other hand, according to the above-mentioned non-patent document 1 and the study by the present inventors, electrolyte salts of alkylene oxide polymers with a high proportion of terminal OH groups (hereinafter sometimes simply referred to as alkylene oxide polymers) It has been found that the cloud point observed in an aqueous solution containing:
- Relatively high temperature.
・The relationship between molecular weight and cloud point differs from that of terminal-capped alkylene oxide in the following points.
The higher the molecular weight, the lower the cloud point may be. (This relationship is the opposite for end-capped alkylene oxide polymers, so it is considered unclear whether there is a linear relationship between molecular weight and cloud point.)
Furthermore, it has been found that in a low molecular weight range, for example, less than 3000, it may be difficult to show a cloud point, especially at relatively low temperatures.
Alkylene oxide polymers in the low molecular weight range as described above have many applications, and the development of efficient production methods will greatly contribute to society.

Therefore, an object of the present invention is to provide a method for producing an alkylene oxide polymer, which includes a method for easily determining the molecular weight during the polymerization process of the alkylene oxide polymer. In particular, the objective was to develop a method for efficiently producing low-molecular-weight alkylene oxide polymers.

The present invention for solving the above problems includes the following aspects.
[1] In the process of producing an alkylene oxide polymer (II) in which 70 mol% or more of the total polymer terminals are OH groups by polymerization of alkylene oxide, the alkylene oxide polymer is produced by the following method. A method for producing an alkylene oxide polymer, which comprises the step of obtaining molecular weight information (II):
(Molecular weight information acquisition process)
a solute (I) containing an electrolyte salt (Ia);
measuring the cloud point of an aqueous solution containing a specific concentration of alkylene oxide polymer (II) extracted from the polymerization process;
A step of estimating the molecular weight of alkylene oxide polymer (II) based on a calibration curve prepared in advance by the following method.
Calibration curve creation method: preparing an aqueous solution containing two or more alkylene oxide polymers (II-n) with known number average molecular weights and different molecular weights at the specific concentration together with the solute (I), The cloud point of each aqueous solution is measured, and the cloud point and number average molecular weight are plotted on a graph with vertical and horizontal axes, respectively, and an approximate line is provided to form a calibration curve.

[2] The method for producing an alkylene oxide polymer according to [1], wherein the electrolyte salt (Ia) has a concentration of 0.1 to 30% by mass.
[3] The solute (I) further contains an organic compound (Ib) having a Hansen solubility parameter (HSP) value of 20 to 35 ((J/cm ³ ) ^0.5 ) [1] or [2] ] The method for producing an alkylene oxide polymer according to.
[4] The method for producing an alkylene oxide polymer according to [3], wherein the organic compound (Ib) is a compound having an HSP value in the range of 20 to 26 ((J/cm ³ ) ^0.5 ).
[5] According to [3] or [4], wherein the concentration of the organic compound (I-b) is 0.5 to 10% by mass, and the concentration of the solute (I) is 0.6 to 35% by mass. A method for producing an alkylene oxide polymer.

[6] The method for producing an alkylene oxide polymer according to any one of [1] to [5], wherein the alkylene oxide polymer (II) has a concentration of 0.3 to 25% by mass.
[7] The method for producing an alkylene oxide polymer according to any one of [1] to [6], wherein the electrolyte salt (Ia) is a salt containing oxygen.
[8] At least one of the two or more alkylene oxide polymers (II-n) having different molecular weights used for creating the calibration curve is an alkylene oxide polymer having a number average molecular weight of less than 3000 [1] to [ 7]. The method for producing an alkylene oxide polymer according to any one of [7].
[9] The alkylene oxide according to [8], wherein the two or more alkylene oxide polymers (II-n) having different molecular weights used for creating the calibration curve are alkylene oxide polymers having a number average molecular weight of 500 or more and less than 3,000. Method for producing polymers.
[10] The method for producing an alkylene oxide polymer according to any one of [1] to [9], wherein the alkylene oxide polymer (II) completes polymerization when the measured molecular weight is less than 3000.

According to the present invention, information on molecular weight can be obtained with relatively high accuracy using a relatively simple method of cloud point measurement using a relatively safe aqueous solution, thereby making it possible to efficiently produce alkylene oxide polymers. It can be carried out.

3 is a calibration curve graph in Example 1. 3 is a calibration curve graph in Example 2. 3 is a calibration curve graph in Example 3. 3 is a calibration curve graph in Example 4. 3 is a calibration curve graph in Example 5. 3 is a calibration curve graph in Example 6.

In the present invention, as disclosed in Non-Patent Document 1, an aqueous solution containing an alkylene oxide polymer (II) having a high proportion of terminal OH groups such as PEG and an electrolyte salt is used as well as a nonionic surfactant. The cloud point of an aqueous solution containing multiple types of alkylene oxide polymers with known molecular weights and electrolyte salts was measured in advance, based on the knowledge that the cloud point changes depending on the molecular weight, and the data was used for calibration. We have discovered a method for producing an alkylene oxide polymer with a desired molecular weight by creating a line and using a method to obtain information on the molecular weight (estimate the molecular weight) of an alkylene oxide polymer with an unknown molecular weight.

That is, the method for producing an alkylene oxide polymer of the present invention is characterized by incorporating a step of obtaining molecular weight information by cloud point measurement as described below in the process of a known method for producing alkylene oxide. More specifically, the method is characterized in that the step of obtaining molecular weight information by cloud point measurement is performed during the alkylene oxide polymerization reaction step. This method can in principle be applied to known alkylene oxide production methods without restriction.

The process of obtaining information on molecular weight based on cloud point used in the present invention is characterized by using a specific aqueous solution. Specifically, this step is characterized by using an aqueous solution containing solute (I) containing electrolyte salt (Ia).

The above electrolyte salt (I-a) includes chloride salts such as lithium chloride, sodium chloride (including common salt), potassium chloride, fluoride salts such as lithium fluoride, sodium fluoride, potassium fluoride, bromide salts, etc. Bromide salts such as lithium, sodium bromide, potassium bromide, iodide salts such as lithium iodide, sodium iodide, potassium iodide, nitrates such as sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassium sulfate, ammonium sulfate, etc. Examples include carbonates such as sulfates, sodium carbonate, potassium carbonate, and ammonium carbonate. Among these, oxygen-containing salts such as carbonates, sulfates, and nitrates are preferred in that cloud point measurement is possible even with a lower polymer concentration. Furthermore, from the viewpoint of metal ions, sodium salts and potassium salts are preferable.

The concentration of the electrolyte salt in the aqueous solution of the electrolyte salt (solution containing water and the electrolyte salt) of the present invention is preferably 0.1 to 30% by mass. A more preferable lower limit is 0.2% by mass, still more preferably 1% by mass, and particularly preferably 2% by mass. On the other hand, the upper limit is more preferably 25% by mass, still more preferably 20% by mass, and particularly preferably 15% by mass. At such a concentration, a low molecular weight polymer, preferably a number average molecular weight of less than 3,000, more preferably less than 3,000, 500 or more, still more preferably less than 3,000, 800 or more, particularly preferably less than 3,000, 1,000 or more. The cloud point can be measured even for alkylene oxide polymers in this range, and information regarding the molecular weight can be obtained.

In the embodiment of the present invention, it seems that the lower the molecular weight of the alkylene oxide polymer (II), the higher the cloud point. is different from (high). Although the reason for this is not clear, it is thought that the alkylene oxide (II) tends to be in a pseudo-crosslinked state due to the presence of an electrolyte salt, and exhibits behavior similar to that of a polymer.
Through studies by the present inventors, it has been found that the alkylene oxide polymer (II) according to the present invention exhibits a certain degree of linear relationship between the cloud point and the molecular weight in a specific embodiment. The present inventors believe that it would be difficult to unambiguously derive a linear relationship between cloud point and molecular weight from conventional knowledge while exhibiting the behavior described above. From this perspective, the relationship between cloud point and molecular weight found this time can be said to be unexpected.

The above electrolyte salt (I-a) has an excellent effect of promoting the release of the alkylene oxide polymer from the aqueous solution at a specific temperature, so even if the alkylene oxide polymer has a low molecular weight as described above, the cloud point This seems to indicate that

The solute (I) used in the measurement of the cloud point further contains an organic compound (I-b) having a Hansen solubility parameter (HSP) in the range of 20 to 35 ((J/cm ³ ) ^0.5 ). I can do it. An organic compound having an HSP value within this range is a compound that exhibits the property of being soluble in water. More preferably, the HSP value is in the range of 20 to 26 ((J/cm ³ ) ^0.5 ).

Such compounds include ethanol (26.5), 1-propanol (24.6), 2-propanol (23.6), n-butanol (23.2), s-butanol (22.2), Monohydric alcohols such as i-butanol (22.7), t-butanol (21.8), ethylene glycol (33.0), diethylene glycol (29.1), triethylene glycol (27.5), etc. Mention may be made of dihydric alcohols. More preferably, it is a monohydric alcohol. The numbers in parentheses are the respective HSP values ((J/cm ³ ) ^0.5 ).
Further, it is preferable that the boiling point of the organic compound (Ib) of the present invention is close to or higher than the boiling point of water, in order to widen the measurement range of the cloud point. Specifically, the boiling point at normal pressure is preferably 60°C or higher, more preferably 75°C or higher, even more preferably 90°C or higher, particularly preferably 95°C or higher. On the other hand, there is no limit on the upper limit value in principle. Preferably it is 300°C, more preferably 250°C.

The concentration of the organic compound (Ib) in the aqueous solution for cloud point measurement of the present invention can be 0 to 10% by mass. When an organic compound is essential, the lower limit is preferably 0.5% by mass, more preferably 1% by mass, and even more preferably 2% by mass. On the other hand, a more preferable upper limit is 8% by mass, and even more preferably 7% by mass.
At such a concentration, even for low molecular weight polymers, preferably alkylene oxide polymers with a number average molecular weight of less than 3000, the cloud point in a relatively low temperature region can be measured and information regarding the molecular weight can be obtained. be able to. As a low molecular weight polymer, the lower limit of the number average molecular weight can be applied up to about 500, the more preferable lower limit is 800, and the still more preferable lower limit is 1000.

The organic compound (I-b) of the present invention has a high effect of liberating the alkylene oxide polymer from an aqueous solution even in a small amount, and especially when used in combination with the electrolyte salt (I-a), the liberating effect is high. It seems that even low molecular weight alkylene oxide polymers exhibit cloud points even at lower temperatures suitable for measurements in aqueous solutions.

The concentration of the solute (the electrolyte salt (I-a) and the organic compound (I-b)) in the aqueous solution used in the present invention is determined by the preferred concentration of each of the electrolyte salt (I-a) and the organic compound (I-b). They can be combined within a range, but when both are included, it is preferably 1.1 to 35% by mass. A more preferable lower limit is 1.2% by mass, still more preferably 2% by mass, and particularly preferably 3% by mass. On the other hand, the upper limit is more preferably 30% by mass, still more preferably 25% by mass, and particularly preferably 20% by mass. As mentioned above, it is possible to measure the cloud point of a polymer in the low molecular weight range without using the organic compound (I-b), but it is preferable to use the electrolyte salt (I-a) and the organic compound (I-b). ) is more useful when used together. This is because the electrolyte salt (I-a) mainly interacts with the alkylene oxide polymer and forms a state where it is easily liberated, and when used together with the organic compound (I-b), the interaction with water is weakened at an accelerated rate. It is thought that this is because the release from water can be effectively promoted.
The above concentration can be appropriately selected depending on the type, molecular weight, terminal structure, etc. of the alkylene oxide.

In the present invention, the alkylene oxide polymer (II) to be dissolved in the aqueous solution for cloud point measurement preferably has a concentration of 0.3 to 25% by mass relative to the aqueous solution. A more preferable lower limit is 0.5% by weight, still more preferably 1% by weight, particularly preferably 2% by weight, particularly preferably 3% by weight. On the other hand, the upper limit is more preferably 20% by mass, further preferably 17% by mass, and particularly preferably 15% by mass. With such a concentration range, the cloud point can be efficiently measured at low temperatures.

The aqueous solution (aqueous solution for cloud point measurement) containing water, solute (I), and alkylene oxide polymer (II) of the present invention is prepared by preparing an aqueous solution containing water and solute (I) as described above. A method of dissolving the alkylene oxide polymer (II) is preferred, but the method is not limited thereto. As long as an aqueous solution meeting the purpose of the present invention is obtained, it can be prepared by contacting water, solute (I), and alkylene oxide polymer (II) in any order. When the solute (I) contains an organic compound (Ib), it is preferable to dissolve the mainly solid electrolyte salt (Ia) in water and then add the organic compound (Ib).

When preparing the aqueous solution for cloud point measurement described above, components other than those described above (other components) can also be used in combination within a range that does not impair the effects of the present invention. The amount of other components used is 5% by mass or less, more preferably 2% by mass or less, still more preferably 1% by mass or less, based on the total of 100% by mass of water, solute, and alkylene oxide polymer. Here, other components typically include a solvent, a catalyst, an initiator, etc. contained in a sample from the polymerization process of an alkylene oxide polymer.

The method for measuring the cloud point of the present invention is not particularly limited, but the following method is preferred. Note that this method is the method used in Examples described later.
Water and solute are mixed at a predetermined ratio to prepare an aqueous solution. Next, this aqueous solution and the alkylene oxide polymer are charged at a predetermined ratio into a glass container equipped with a temperature sensor and a stirring device to form an aqueous solution. Next, this aqueous solution is heated, and when the turbidity of the solution becomes uniform, it is gradually cooled (in air) while checking the solution temperature. The temperature at which the liquid changes from cloudy to clear is the cloud point.

In the method of the present invention, it is necessary to prepare a calibration curve in advance in order to obtain information regarding the molecular weight from the cloud point of the polymer during the polymerization process. As shown in the example data described below, we found that the alkylene oxide polymer (II) according to the present invention exhibits a linear relationship to some extent between cloud point and molecular weight in an environment in which multiple electrolyte salts and organic compounds are used together. ing. From this, a calibration curve can be obtained as follows.
The calibration curve is created by measuring the cloud points of two or more polymers with different molecular weights using the cloud point measuring method described above, setting the cloud point and molecular weight on the vertical and horizontal axes, and comparing them. It can be obtained by creating a graph plotting the relationship between and providing an approximation line. It is arbitrary to set the vertical axis or the horizontal axis to either item. The approximate line is an approximate curve that is optimized to pass through as many plot points as possible, and is the optimal approximate curve that is installed as a standard function in commercially available spreadsheet software (for example, Microsoft's product name "Excel"). You can select and use a curve.

A calibration curve can be obtained if two or more types of polymers with different molecular weights are used. It is preferable to select the molecular weight of the polymer for creating a calibration curve within a range that includes the target molecular weight of the desired alkylene oxide polymer, but of course, as long as the target molecular weight is within the range that allows the desired effect to be obtained. Even if the molecular weight is outside the molecular weight range of the polymer used to create the calibration curve, the molecular weight can be estimated by extending (extrapolating) the calibration curve. Moreover, the more types there are, the more accurate a calibration curve can be created. The preferable lower limit of the types of polymers used for creating the calibration curve is 3 types, more preferably 4 types, and still more preferably 5 types. On the other hand, if the number of types is increased too much, the improvement in accuracy may be small compared to the number of man-hours. Although it depends on the range setting of the molecular weight to be measured, the preferable upper limit of the types of polymers used for creating the calibration curve is 15 types, more preferably 10 types. Of course, it goes without saying that it is preferable that the molecular weights of the respective polymers have an appropriate difference.

In particular, in the present invention, when the purpose is to produce an alkylene oxide polymer with a molecular weight of less than 3,000, it is important that at least one of the polymers for creating a calibration curve is an alkylene oxide polymer with a number average molecular weight of less than 3,000. be. It is more preferable to use alkylene oxide polymers having a number average molecular weight of less than 3000 as all of the polymers for preparing the calibration curve.
The lower limit of the number average molecular weight of the polymer for preparing a calibration curve of the present invention is preferably 500, more preferably 800.
In addition, if the purpose is to produce an alkylene oxide polymer with a molecular weight of 3000 or more, a calibration curve may be created using a higher molecular weight polymer for creating a calibration curve and a polymer with a molecular weight close to the target molecular weight.

At this time, the concentration of each component can be selected as appropriate depending on the target molecular weight range, but for polymers with different molecular weights, it is necessary to keep the measurement conditions other than the molecular weight the same, such as the concentration. Yes. Of course, the cloud point measurement of the sample for determining the molecular weight must also be carried out under similar conditions.

For polymers with different molecular weights for creating a calibration curve, use a polymer whose number average molecular weight has been determined in advance by a known molecular weight measurement method, such as the GPC method or hydroxyl value (applicable to polymers with a known number of functional groups). . Such a polymer may be obtained by the polymerization method described below, or may be a commercially available product. It is preferable that the polymer for creating a calibration curve has the same composition as the polymer to be polymerized as a sample, but when producing a copolymer, it may be difficult to have the same composition in a strict sense. be. Therefore, it is of course possible to adopt the "method of obtaining so-called conversion information" regarding the molecular weight of the polymer to be measured using a calibration curve obtained using a calibration curve sample of a homopolymer (with the GPC method, the polystyrene equivalent value (This is the same idea as the method used to define the molecular weight of various polymers.)

After creating a calibration curve, cloud point measurement in the production process of an alkylene oxide polymer, which will be described later, is carried out as follows.
Using a polymer sample obtained by extraction from the reaction apparatus during the above manufacturing process, the cloud point is measured under the same conditions as when measuring the calibration curve. Information on the molecular weight corresponding to the cloud point is read (estimated) from the calibration curve and recorded as the molecular weight.
Thereby, information on the molecular weight during the polymerization process can be obtained with good response. Of course, in order to obtain more accurate information, the molecular weight of the same sample may be subsequently measured by GPC or the like.

The method for producing an alkylene oxide polymer of the present invention is not particularly limited as long as it includes the step of obtaining molecular weight information by measuring the cloud point described above. A typical example is a method in which a corresponding alkylene oxide is polymerized in the presence of a reaction solvent and a catalyst to obtain an alkylene oxide polymer.
Of course, it is also possible to apply the present invention to a method for producing an alkylene oxide polymer in which alkylene glycol is subjected to dehydration condensation in the presence of a basic catalyst. Examples of alkylene oxide polymerization methods will be described below.

(alkylene oxide)
The alkylene oxide used in the ring-opening polymerization reaction of the present invention is not particularly limited, and ethylene oxide having 2 carbon atoms and alkylene oxide having 3 or more carbon atoms can be preferably used. Examples of the alkylene oxide having 3 or more carbon atoms include propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, and epichlorohydrin. Two or more types of these can be used in combination. As will be described later, one preferred embodiment is to use an alkylene oxide having 3 or more carbon atoms in combination with ethylene oxide. Among these alkylene oxides, ethylene oxide and propylene oxide are preferred.

Furthermore, it may be difficult to obtain a high polymer using ethylene oxide alone, but it may be easier to obtain a high polymer when copolymerized with an alkylene oxide having 3 or more carbon atoms. In such a case, a particularly preferred alkylene oxide having 3 or more carbon atoms is propylene oxide.
Further, a cyclic ester such as a lactone may be used in combination with the alkylene oxide.
In the present invention, it is particularly preferable to carry out polymerization containing ethylene oxide as a main component, considering the wide range of uses of the polymer.

(Catalyst and initiator)
In the alkylene oxide polymerization method according to the present invention, a catalyst and an initiator are usually used. Examples of the catalyst include known catalysts such as basic compounds such as caustic soda and metal compounds. As the initiator, water, polyol, or monool compound can be used. Specifically, polyols and monool compounds are the following compounds.

Examples of the polyol include polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, trimethylolpropane, and glycerin, and polyether polyols having 2 to 12 hydroxyl groups and a molecular weight of about 300 to 900. The number of hydroxyl groups in the polyether polyol is preferably 2 to 8, particularly preferably 2 to 3.

Examples of monools include alcohols with 1 to 12 carbon atoms such as methanol and ethanol, and polyether monools with a molecular weight of 300 to 900 obtained by ring-opening polymerization of alkylene oxide using an alkali catalyst or a cationic catalyst. .
As will be described later, the alkylene oxide polymer (II) of the present invention has a structure in which most of the terminal ends are OH groups. Therefore, when using a monool as an initiator, it is preferable to use it in combination with the above-mentioned polyol.

These initiators are preferably supplied to the polymerization reaction system together with the catalyst at the beginning of the polymerization reaction. Further, during the polymerization reaction, the initiator may be supplied alone or together with alkylene oxide to the reaction system. Initiators that can be supplied during the polymerization reaction include water, dihydric alcohols such as propylene glycol, ethylene glycol, dipropylene glycol, and diethylene glycol, trihydric alcohols such as glycerin, and trimethylolpropane, in addition to the above-mentioned low molecular weight polyether polyols. Alcohol can be used.

(Alkylene oxide supply rate)
In the process of the ring-opening polymerization reaction of alkylene oxide in the present invention, the supply rate of alkylene oxide does not need to be constant and may be varied to some extent. Therefore, in the present invention, the alkylene oxide supply rate may be expressed as an average supply rate.
Generally, it is preferable to feed the alkylene oxide faster in the middle stage of the polymerization process than in the final stage. Specifically, the ratio of the supply speed in the middle stage and the final stage is preferably in the range of 1.2 to 6.0. Within this range, alkylene oxide can be efficiently produced.

(Polymerization temperature)
The polymerization temperature is not particularly limited, but is usually 110°C or higher, preferably 125°C or higher, and particularly preferably 135°C or higher. By setting the polymerization temperature higher, it is possible to easily remove heat from the polymerization reaction system, increase the average supply rate of alkylene oxide during the entire process of the polymerization reaction, and increase the productivity of alkylene oxide polymers. . Moreover, in the case of the same average feed rate, an alkylene oxide polymer having a lower viscosity and a narrower molecular weight distribution can be obtained by increasing the temperature. Further, the polymerization temperature is preferably 160°C or lower, particularly preferably 150°C or lower. If the polymerization temperature is too high, the catalyst may be deactivated.

(Alkylene oxide polymer)
In the alkylene oxide polymer (II) obtained by the production method of the present invention, 70 mol% or more of all the terminals are OH groups, with 100 mol%. Preferably it is 80 mol% or more, more preferably 85 mol% or more, particularly preferably 90 mol% or more. The molecular weight of the alkylene oxide polymer (II) used in the present invention is not particularly limited as long as the cloud point can be measured, but the lower limit is preferably 500, more preferably 800. On the other hand, a preferable upper limit is 100,000, more preferably 50,000, and even more preferably 10,000. Further, as described above, the molecular weight of the alkylene oxide polymer (II) used in the present invention may be less than 3,000. Alkylene oxide polymer (II) of the present invention The preferable range of the hydroxyl value of the alkylene oxide polymer (II) obtained in the present invention may vary depending on the repeating structural unit and terminal structure, but for example, it is linear and has hydroxyl groups. When the polyether diol has two polyether diols per molecule (corresponding to the embodiment in which 100% of all polymer terminals are OH groups), the preferable range of the hydroxyl value is 5 or more and 250 or less. A more preferable lower limit is 10, still more preferably 15, and particularly preferably 20. On the other hand, the upper limit of the hydroxyl value is more preferably 200, still more preferably 170, and particularly preferably 150. The hydroxyl value can be measured in accordance with method A or method B of JIS K1557 "Testing methods for plastics - polyurethane raw material polyols - Part 1: How to determine hydroxyl value". The unit of hydroxyl value is (mgKOH/g).

(Application)
An example of the use of the alkylene oxide polymer obtained by the production method of the present invention is, for example, in the production of elastic polyurethane foam. When producing elastic polyurethane foam, it is preferable that the alkylene oxide polymer (polyether polyol) has an oxyethylene group at the end. A polyether polyol having an oxyethylene group at the end can be produced by using a block polymerization method and reacting ethylene oxide in the final step. As the catalyst used in this case, suitable alkali catalysts include alkali metals such as sodium and potassium, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkali metal alkoxides such as sodium alkoxide and potassium alkoxide. can.

The alkylene oxide polymers obtained by the process of the invention are also suitable for the production of polyurethane elastomers. It can also be used as a polymer-dispersed polyol containing fine polymer particles.
The alkylene oxide polymer obtained by the method of the present invention can also be used as a surfactant, a lubricating oil, and the like.

(Measurement of cloud point)
1. The following 12 types of polyethylene glycols whose materials and number average molecular weights were specified (100 mol% of the polymer terminals are OH groups)
Molecular weight: 562, 587, 692, 795, 889, 1004, 1372, 1496, 1968, 1975, 2826, 2960
・Prepare an aqueous solution with the following concentration using pure water and commercially available reagents: sodium chloride, sodium sulfate, sodium carbonate, potassium carbonate, and 1-propanol.
Sodium chloride: 25 wt% aqueous solution Sodium sulfate: 12 wt% aqueous solution Sodium carbonate: 5 wt% aqueous solution, 10 wt% aqueous solution Potassium carbonate: 12.4 wt% aqueous solution 1-Propanol: 2 wt% aqueous solution, 5 wt% aqueous solution

2. Cloud Point Measuring Method The following operations were performed according to the conditions shown in Tables 1 to 6 below.
A test tube with an outer diameter of about 30 mm and a length of about 125 to 150 mm is charged with various aqueous solutions of specific concentrations, the above-mentioned polyethylene glycol, and pure water in a weight ratio that provides a predetermined polymer concentration.
The test tube is equipped with a stirring device and a temperature sensor, sealed, and heated in an oil bath while stirring until the turbidity becomes constant. (Inner temperature is generally below 100℃)
Thereafter, it is taken out from the oil bath, slowly cooled (air cooled) while stirring, and the temperature at which it becomes transparent is recorded. (One operation takes approximately 15 to 20 minutes to complete.)
The above operation is performed three times, and the average value is taken as the cloud point.

Example 1 (using sodium chloride aqueous solution)
The cloud point was measured under the conditions shown in Table 1.
The results were plotted in a graph with the horizontal axis: cloud point and the vertical axis: molecular weight, as shown in Figure 1.

As is clear from FIG. 1, when an aqueous sodium chloride solution was used, it was confirmed that the cloud point changed in the same manner depending on the molecular weight, regardless of the concentration of polyethylene glycol (PEG).

Example 2 (using sodium sulfate aqueous solution)
The cloud point was measured under the conditions shown in Table 2.
The results were plotted in a graph with the horizontal axis: cloud point and the vertical axis: molecular weight, as shown in FIG.

As is clear from FIG. 2, it was confirmed that when an aqueous sodium sulfate solution was used, a change in cloud point depending on the molecular weight could be observed even with a lower concentration of polyethylene glycol (PEG).

Example 3 (using sodium carbonate aqueous solution)
The cloud point was measured under the conditions shown in Table 3.
The results were plotted in a graph with the horizontal axis: cloud point and the vertical axis: molecular weight, as shown in Figure 3.

As is clear from FIG. 3, when using an aqueous sodium carbonate solution, it is possible to measure the optimal cloud point for each by dividing the calibration curve into molecular weights of about 1000 or less and molecular weights of about 1500 or more and less than 3000.

Example 4 (using potassium carbonate aqueous solution)
The cloud point was measured under the conditions shown in Table 4.
The results were plotted in a graph with the horizontal axis: cloud point and the vertical axis: molecular weight, as shown in FIG.

As is clear from Figure 4, when an aqueous potassium carbonate solution is used, the cloud point is widely distributed in the molecular weight range of approximately 1500 or less, and it is clear that it is possible to obtain more detailed molecular weight information within this range. .

As can be seen from the results of Examples 1 to 4 above, it can be seen that there is a certain relationship between the cloud point and the molecular weight of polyethylene glycol. Therefore, if this graph is used as a calibration curve, information on the molecular weight can be obtained from the cloud point of polyethylene glycol of unknown molecular weight. Since the slope of the graph of cloud point and molecular weight differs depending on the combination of aqueous solutions used, more accurate molecular weight information can be obtained by selecting conditions suitable for the purpose and conducting the measurement. Furthermore, in contrast to Example 1, in Examples 2 to 4 in which oxygen-containing salts such as sulfate and carbonate were used, it was possible to measure the cloud point of a lower molecular weight with a smaller amount of polymer.

Example 5 (using potassium carbonate/1-propanol aqueous solution)
Cloud point was measured under the conditions shown in Table 5. Note that the HSP value of 1-propanol is 24.6 ((J/cm ³ ) ^0.5 ).
The results were plotted in a graph with the horizontal axis: cloud point and the vertical axis: molecular weight, as shown in FIG. FIG. 5 also shows the results of Example 4 in which 1-propanol was not added (0%).

Example 6 (using sodium sulfate/1-propanol aqueous solution)
The cloud point was measured under the conditions shown in Table 6.
The results were plotted in a graph with the horizontal axis: cloud point and the vertical axis: molecular weight, as shown in FIG. FIG. 6 also shows the results of Example 2 (salt concentration and PEG concentration are the same) in which 1-propanol was not added (0%).

From the results of Examples 5 and 6 above, it is clear that when an aqueous solution containing 1-propanol, which corresponds to an organic compound with an HPS of 20 to 35 ((J/cm ³ ) ^0.5 ), the cloud point is 1- It can be seen that the overall value is lower than in the example in which propanol was not added. In the method of measuring the cloud point in a room temperature atmosphere, the rate of temperature decrease during measurement tends to decrease as the temperature approaches room temperature, so it can be considered that the measurement is easier.
Therefore, it can be seen that the method using an aqueous solution containing a specific organic compound is a preferable method for obtaining molecular weight information of lower molecular weight polymers.

Example 7 (Production of polyethylene glycol 1540)
Addition polymerization of ethylene oxide was carried out in a batch process using a 27% aqueous sodium hydroxide solution as a catalyst and diethylene glycol as an initiator.
When the prescribed amount of ethylene oxide had been supplied, the cloud point of the polymer (from the manufacturing method, it is clear that 100 mol% of all polymer terminals are OH groups) under the conditions shown in Table 5 was 60. The temperature was .1°C. The molecular weight was estimated to be 588 from the calibration curve in FIG. 5, and it was obtained as an unneutralized polyethylene glycol 600 product.
A catalytic amount of 48% potassium hydroxide aqueous solution was added to the unneutralized polyethylene glycol 600 obtained above, and after dehydration by heating under reduced pressure conditions, ethylene oxide was continuously supplied to synthesize polyethylene glycol 1540. went. The polymer in the middle was sampled to confirm the molecular weight, and the cloud point was measured under the conditions shown in Table 1 (polymer concentration 15 wt%), and it was found to be 70.1°C. The molecular weight was estimated to be 1398 from the calibration curve in FIG. Subsequently, ethylene oxide was supplied, and when the predetermined amount had been supplied, the cloud point was measured under the conditions shown in Table 1 and found to be 67.8°C. The molecular weight was estimated to be 1525 from the calibration curve in FIG. When the insufficient amount of ethylene oxide was supplied and the cloud point was measured again, it was 67.5°C. The molecular weight was estimated to be 1543 from the calibration curve in FIG. The molecular weight determined from the hydroxyl value of the polyethylene glycol obtained after neutralization and catalyst removal by a known method was 1558, giving polyethylene glycol 1540 in the target molecular weight range. Using this method, it is possible to measure and confirm the molecular weight easily and in a relatively short time, so that polymerization conditions (polymerization time, etc.) can be determined with good response.

Claims (10)

In the process of producing an alkylene oxide polymer (II) in which 70 mol% or more of the total polymer terminals are OH groups by polymerization of alkylene oxide, the alkylene oxide polymer (II) is produced by the following method. A method for producing an alkylene oxide polymer, comprising the step of obtaining molecular weight information of:
(Molecular weight information acquisition process)
a solute (I) containing an electrolyte salt (Ia);
measuring the cloud point of an aqueous solution containing a specific concentration of alkylene oxide polymer (II) extracted from the polymerization process;
Step of estimating the molecular weight of alkylene oxide polymer (II) based on a calibration curve prepared in advance by the following method:
Calibration curve creation method: preparing an aqueous solution containing two or more alkylene oxide polymers (II-n) with known number average molecular weights and different molecular weights at the specific concentration together with the solute (I), The cloud point of each aqueous solution is measured, and the cloud point and number average molecular weight are plotted on a graph with vertical and horizontal axes, respectively, and an approximate line is provided to form a calibration curve. The method for producing an alkylene oxide polymer according to claim 1, wherein the concentration of the electrolyte salt (Ia) is 0.1 to 30% by mass. The alkylene according to claim 1 or 2, wherein the solute (I) further contains an organic compound (Ib) having a Hansen solubility parameter (HSP) value in the range of 20 to 35 ((J/cm ³ ) ^0.5 ). Method for producing oxide polymer. The method for producing an alkylene oxide polymer according to claim 3, wherein the organic compound (Ib) is a compound having an HSP value in the range of 20 to 26 ((J/cm ³ ) ^0.5 ). The alkylene oxide polymer according to claim 3 or 4, wherein the concentration of the organic compound (I-b) is 0.5 to 10% by mass, and the concentration of the solute (I) is 0.6 to 35% by mass. manufacturing method. The method for producing an alkylene oxide polymer according to any one of claims 1 to 5, wherein the concentration of the alkylene oxide polymer (II) is 0.3 to 25% by mass. The method for producing an alkylene oxide polymer according to any one of claims 1 to 6, wherein the electrolyte salt (Ia) is a salt containing oxygen. Any one of claims 1 to 7, wherein at least one of the two or more types of alkylene oxide polymers (II-n) having different molecular weights used for creating the calibration curve is an alkylene oxide polymer having a number average molecular weight of less than 3,000. A method for producing an alkylene oxide polymer as described in . The alkylene oxide polymer according to claim 8, wherein the two or more alkylene oxide polymers (II-n) having different molecular weights used for creating the calibration curve are alkylene oxide polymers having a number average molecular weight of 500 or more and less than 3,000. Production method. The method for producing an alkylene oxide polymer according to any one of claims 1 to 9, wherein the alkylene oxide polymer (II) completes polymerization when the measured molecular weight is less than 3,000.

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