JPH1025340A - Production of polyether diol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production process for a polyether diol of which the number-average molecular weight can be finely controlled. SOLUTION: When polyether diol is produced by copolymerization of tetrahydrofuran and/or other cyclic ether copolymerizable therewith or a polyhydric alcohol, a heteropolyacid which has a structure formed by condensation reaction of an at least one oxide selected from those of Mo, W and V with an oxyacid selected from those of P, Si, As and Ge where the atomic ratio of the former oxide to the latter oxyacid is 2.5-12 is used as a catalyst. To this polymerization reaction system, are added water in an amount enough to form two phases of the aqueous layer and the organic layer containing the raw materials, and the reaction temperature and the residential time in the catalyst phase are kept constant during the passage of the reaction and the specific gravity of the catalyst phase is controlled to adjust the molecular weight of the polyether diol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a homopolymer of tetrahydrofuran (hereinafter referred to as THF) and / or a copolymer of THF (hereinafter referred to as THF copolymer) using a heteropolyacid as a catalyst. (Referred to as coalescence).

[0002]

2. Description of the Related Art A THF polymer or a THF copolymer is
It is an industrially useful polymer used as a main raw material of polyurethane used for polyurethane elastic yarn (spantex) and synthetic leather, an additive for oil, a softener, and the like. In these industrial applications, these polymers having an optimum molecular weight depending on the application have various molecular weights.

As a method for producing a THF polymer or a THF copolymer, US Pat. No. 4,568,775 and US Pat. No. 4,568,775 disclose that a heteropolyacid can be used as a polymerization catalyst.
No. 6,580,655 and US Pat. No. 5,416,240. These disclosures refer to the catalytic activity of heteropoly acids. However, there is no mention of a method for controlling the molecular weight of the obtained THF polymer.

As one method for obtaining a polyether diol having an optimum molecular weight according to various uses, for example, as disclosed in Japanese Patent Publication No. Sho 60-42421, a polymerized polyether diol is fractionated by molecular weight. There is known a method of selecting a low molecular weight substance or a high molecular weight substance to obtain a polymer having an arbitrary molecular weight. However, this method requires a separation step in addition to the polymerization step, and uses an organic solvent, so that it has a drawback that the cost of recovery and the like is added and the method is economically disadvantageous.

JP-A-5-70585 discloses a method for controlling the average molecular weight of the resulting polyoxyalkylene glycol and its derivative by controlling the conductivity of a heteropolyacid catalyst phase in a polymerization reaction system. I have. In the ring-opening polymerization of THF using a heteropoly acid as a catalyst, the crystallization water of the heteropoly acid is partially removed,
It proceeds by activation of THF in a coordinated state via a proton (catalyst, 33 [1] 1991 p.
34 and the surface, 30 [1] (1992) p. 67). Therefore, the proportion of protons in the catalyst greatly affects the catalytic activity and is important. Since the molecular weight of the polyether diol obtained by changing the catalytic activity changes, the molecular weight can be controlled by controlling the proportion of protons in the catalyst. One of the specific examples is disclosed in the aforementioned Japanese Patent Application Laid-Open No. 5-70585.
This is a molecular weight control based on a conductivity control disclosed in Japanese Patent Application Laid-Open Publication No. H11-163,036. However, even if the conductivity of the catalyst phase is controlled, the number average molecular weight of the polyether diol obtained does not fluctuate greatly and is not satisfactory. That is, in the polyether diol formation by the ring-opening polymerization of THF using a heteropolyacid catalyst, it is considered that water in the catalyst phase forms a terminal —OH group. It is presumed that water coordinates with the heteropolyacid anion, and the conductivity changes depending on the coordination state of the water. Is difficult to keep small. Furthermore, in this method, a slight contamination of the electrode for measuring the conductivity changes the indicated value of the conductivity, and the molecular weight may be controlled based on the wrong conductivity. In order to control the molecular weight accurately, it is necessary to wash the electrode frequently, and it is difficult to use the electrode industrially.

[0006]

The polyether diol may be used alone as an additive or the like, but in many cases, it is used as a reaction raw material and has a certain number average molecular weight, particularly, a number average molecular weight of 600. Those having a constant value in the range of ３3000 are required. When using polyether diol as a reaction raw material, it is possible to measure the molecular weight and use it for the reaction each time the reaction is performed, but complicated equipment and processes such as setting up an online measuring device and changing the reaction charge based on the result are necessary. It is difficult to implement industrially.

Thus, it has an optional number average molecular weight,
There is a demand for a method for producing a polyether diol which can control the variation of the number average molecular weight within a narrow range with high accuracy. In addition, a method for producing a polyether diol using a heteropolyacid as a catalyst has attracted attention because it allows the presence of water in a reaction system. In the production of a polyether diol using the catalyst, the molecular weight of the polymer is precisely adjusted. In particular, there is a need for a control method.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a process for producing a polyether diol by polymerization with tetrahydrofuran and / or a cyclic ether or polyhydric alcohol copolymerizable therewith, which is selected from Mo, W and V. A heteropolyacid having a structure in which at least one oxide and an oxyacid selected from P, Si, As, and Ge are condensed and having an atomic ratio of the former to 2.5 to 12 as a catalyst, In the polymerization reaction system, the amount of water that forms two phases of the raw material organic phase and the catalyst phase is present, and the reaction temperature and the catalyst phase residence time during the reaction time are kept constant, and the specific gravity of the catalyst phase is reduced. A method for producing a polyether diol, wherein the molecular weight of the polyether diol is adjusted by controlling.

[0009] The amount of water coordinating to the heteropolyacid has an effect on the catalytic activity and, under a given reaction temperature and catalyst phase residence time, the amount of water coordinating and the number average molecular weight of the resulting THF polymer. Has a correlation with that of JP-A-59-2213.
No. 26 is disclosed. The present inventors have proposed to control the molecular weight of a THF polymer or copolymer to be polymerized by maintaining a constant coordination water of a catalyst in a reaction system under a constant reaction temperature and a relative catalyst residence time. As a result of examining, by measuring the specific gravity of the catalyst phase, by keeping the specific gravity constant,
By controlling the amount of water including the number of coordinating waters present in the catalyst phase in the reaction system, the molecular weight of the obtained THF polymer and / or THF copolymer can be precisely controlled.

THF and / or heteropolyacid catalyzed
Alternatively, in the polymerization of a cyclic ether or a polyhydric alcohol copolymerizable with THF, the reaction solution is stirred to perform the reaction uniformly and for a predetermined time. At this time, the reaction system forms a solution in which two phases of a monomer phase containing a polymer and a catalyst phase are dispersed in an emulsion state. In the present invention, the catalyst phase residence time is a value obtained by dividing the volume of the catalyst phase in the reaction system in the continuous polymerization by the feed amount of the monomer,
It is a measure of reaction time. In batch polymerization, it can be expressed by the contact time between the catalyst phase and the monomer phase.

The specific gravity of the catalyst phase in the present invention means the specific gravity of the catalyst phase in the emulsion solution in the reaction system.
In order to control the specific gravity of the catalyst phase in the state of being dispersed in the form of an emulsion, the specific gravity is measured. Then, the specific gravity of the catalyst phase is measured, and after the measurement, the two phases can be returned to the reaction system.

Although the specific gravity measurement is not particularly limited, a method for measuring Coriolis force generated when a liquid flows in a pipe, a method for bending a U-shaped pipe when flowing through a U-shaped pipe having a fixed volume, and Known methods such as measurement of the amount can be adopted. In a commercial method, it is preferable to measure the specific gravity as continuously as possible by online measurement or the like, and to control the specific gravity constant. The control of the specific gravity of the catalyst phase in the reaction system can be realized by controlling the amount of water added to the reaction solution or excluded from the reaction system. Water in the reaction system is distributed between the catalyst phase and the monomer phase, and the amount of water distributed in the catalyst phase in which the reaction proceeds affects the average molecular weight of the generated THF polymer or copolymer. . That is, the specific gravity of the catalyst phase and the average molecular weight of the produced polymer differ depending on the heteropolyacid used, the monomer composition, the reaction temperature and the residence time of the catalyst phase, but there is a clear correlation under certain conditions. For example, phosphotungstic acid is used as the heteropolyacid, and the reaction temperature is 58%.
When THF alone is polymerized under the conditions of a reaction temperature of 4 ° C. and a reaction time of 4 hours, the resulting polytetramethylene glycol (hereinafter PT
The number average molecular weight (referred to as MG) is shown in FIG.

As described above, the number average molecular weight of the obtained polyether diol and the specific gravity of the catalyst have a clear correlation under the conditions of constant reaction temperature and reaction time. This correlation is represented by the following general formula (1).

(Equation 1) Here, Mn is the number average molecular weight of the THF polymer or copolymer, ρ is the specific gravity of the catalyst phase, and a and b are constants that vary depending on the reaction temperature, time, monomer composition, and catalyst system. Like this
The number average molecular weight of the produced THF polymer or copolymer can be controlled by controlling the specific gravity of the catalyst phase.
At this time, the specific gravity of the catalyst phase is preferably kept within a range of ± 0.2%, more preferably within a range of ± 0.1%. By controlling the variation of the specific gravity of the catalyst phase within the variation range of ± 0.2%, the water in the catalyst phase can be suppressed to within 0.1%, and the resulting THF polymer or copolymer can be reduced. The molecular weight can be controlled within ± 100 and further within ± 50. TH using heteropoly acid as catalyst
The molecular weight of the polyether diol obtained by the polymerization of F and / or an environmental ether or polyhydric alcohol copolymerizable therewith can be controlled via the specific gravity of the catalyst phase in the reaction system. If the above-mentioned general formula (1) is previously determined for the correlation depending on the polymerization reaction conditions (monomer composition, reaction temperature, time, catalyst system), the THF polymer or copolymer to be obtained will have a catalyst phase specific gravity. By controlling the above, a polymer having an arbitrary number average molecular weight can be obtained, and its fluctuation is small, and a polymer having a substantially constant molecular weight can be obtained.

In the production of the polyether diol according to the present invention, in addition to the homopolymerization of THF, a cyclic ether or diol copolymerizable with THF can be used as a monomer. Examples of such monomers include oxetanes and oxetane derivatives such as 3,3-dimethyloxetane,
Cyclic ethers such as methyltetrahydrofuran, 1,3-dioxolane, tetrahydropyran and / or ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexane Examples thereof include diol, neopentyl glycol, diethylene glycol, dipropylene glycol and the like.

The heteropolyacid according to the present invention is Mo,
At least one oxide of W and V and another element;
For example, it is a general term for oxyacids formed by condensation of oxyacids such as P, Si, As, and Ge. The atomic ratio of the former to the latter is 2.5 to 12, particularly preferably 12 or 9. Specific examples of these heteropolyacids include phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdung tungstovanadic acid, phosphorus tungstovanadic acid, phosphomolybdniobic acid, silicotungstic acid , Molybdic acid, silicate molybdung tungstic acid, silicate molybdenum tungstovanadate, germanium tungstate, arsenic molybdate, arsenic tungstate, and the like.

The amount of the heteropolyacid to be used is not particularly limited. However, if the amount of the heteropolyacid in the reaction system is small, the polymerization rate is low, and the amount is 0.1 to 20 times, preferably 0.5 to 5 times the weight of the monomer. Quantity. When the polymerization temperature is increased, the degree of polymerization tends to decrease due to depolymerization of the polymer, and the polymerization temperature is preferably from 0 to 150 ° C, particularly preferably from 30 to 80 ° C, in view of the polymerization yield.

The reaction time varies depending on the amount of the catalyst and the reaction temperature, but is usually 0.5 to 20 hours. Since the polymerization reaction can be carried out while stirring the monomer and the heteropolyacid, a solvent is not particularly required, but a solvent inert to the reaction may be added in some cases. The specific gravity of the catalyst phase during the reaction varies depending on the heteropolyacid used, but when no solvent is contained, it is usually selected from the range of 1.3 to 3.0, and from the viewpoint of catalytic activity, 8 molecules per 1 heteropolyacid molecule. It is selected in the range containing the following water. In addition, when the amount of water in the reaction system increases, the specific gravity of the catalyst phase decreases, and it becomes difficult to separate from the monomer phase. Further, when the amount of water further increases, two phases no longer form. Therefore, the specific gravity of the catalyst phase has an appropriate range depending on the polymerization reaction conditions used.

As described above, in the polymerization of THF and / or a comonomer copolymerizable therewith using a heteropolyacid as a polymerization catalyst, by controlling the specific gravity of the catalyst phase, it has a desired molecular weight and its fluctuation is small. A polyether diol can be produced, and after the reaction, the monomer is removed from the phase mainly composed of the monomer and the polymer by distillation or the like by phase separation to obtain a polyether diol.

[0019]

The present invention will be described below with reference to examples. In the following examples, the number average molecular weight is a value calculated from the OH value measurement. Examples 1 to 12 Polymerization was performed using a continuous polymerization apparatus shown in FIG. First, 50
In a 0 mL reactor (1) with a stirrer and reflux condenser,
140 g of the catalyst shown in Table 1 was charged, and THF (monomer) was added.
Is added and stirred. The reactor temperature is set to a predetermined temperature, and the monomer is fed to the reactor (1) at a rate of 50 g / H. Circulating the reaction solution with the phase separation tank (2);
The phase-separated upper phase is withdrawn at a rate of 30 g / H. Using a densitometer (3) installed in a circulation line from the phase separation tank (2) to the reactor (1) during the reaction, from the water supply tank (4) to the reactor (1) so as to have a predetermined density. Adjust the amount of water supply. The liquid extracted from the phase separation tank (2) was supplied to the distillation column (5) to remove unreacted monomers, thereby obtaining a polyether diol.

Table 1 summarizes the specific gravity of the catalyst phase, the number average molecular weight of the polyether diol, and the fluctuation range of the number average molecular weight measured every 10 hours after continuous operation for about 100 hours.

[0021]

[Table 1]

[0022]

As described above, the method for producing a polyether diol according to the present invention controls the specific gravity of the heteropolyacid catalyst phase to obtain a polyether diol having an arbitrary molecular weight depending on the application and having a small variation in the molecular weight. Can be manufactured.

[Brief description of the drawings]

FIG. 1 shows TH using phosphotungstic acid as a catalyst.
The figure which shows the correlation between the number average molecular weight of PTMG obtained in the homopolymerization of F, and the catalyst phase specific gravity at the time of reaction.

FIG. 2 is a schematic view of a continuous polymerization tank used in Examples. In FIG. 2, 1 indicates a reactor, 2 indicates a phase separation tank, 3 indicates a hydrometer, 4 indicates a water supply tank, and 5 indicates a distillation column.

Claims (1)

[Claims] When producing a polyether diol by polymerization with tetrahydrofuran and / or a cyclic ether or polyhydric alcohol copolymerizable therewith, M
at least one oxide selected from o, W, and V;
A structure in which an oxyacid selected from Si, As, and Ge is condensed, and a heteropolyacid having an atomic ratio of the former to 2.5 to 12 as a catalyst is used as a catalyst. The amount of water that forms two phases with the catalyst phase is present, the reaction temperature during the course of the reaction and the catalyst phase residence time are kept constant, and the molecular weight of the polyether diol is controlled by controlling the specific gravity of the catalyst phase. A method for producing a polyether diol, wherein the method is adjusted.