JPH1087811A - Production of copolyether polyol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a copolymer PTMG by the copolymerization of tetrahydrofuran with a 2-10C diol in such a manner that it is reduced in the fluctuation of the content of a specified comonomer. SOLUTION: In producing a copolyester polyol from tetrahydrofuran and a 2-10C diol in the presence of a catalyst comprising a heteropoly acid, part of the contents is continuously withdrawn from a reaction tank 1 and is divided into two layers. The lower layer is returned to the tank 1, while the upper layer is returned to the tank 1 after the water contained therein is distilled out of the system by vaporization together with tetrahydrofuran, and the distillate is returned to the tank 1 after water is removed therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyether polyol (hereinafter referred to as copolymer) obtained by copolymerizing tetrahydrofuran (hereinafter abbreviated as THF) and a diol having 2 to 10 carbon atoms (hereinafter abbreviated as diol). (Abbreviated as PTMG)
And a method for producing the same.

[0002]

2. Description of the Related Art Polyoxytetramethylene glycol (hereinafter abbreviated as PTMG) is an industrially useful polymer widely used as a main raw material for elastic bodies, elastic fibers and elastic structures made of polyurethane or the like. . recent years,
THF and a diol having 2 to 10 carbon atoms (diol),
For example, neopentyl glycol (hereinafter abbreviated as NPG)
And polyether polyol (copolymerized PTM)
G) is attracting attention. The copolymerized PTMG is PTMG
As compared with those using PTMG, elongation, hysteresis loss, low-temperature properties, etc. are remarkably improved as compared with those using PTMG. For example, in the case of a polyurethane elastic fiber, the conventional product using PTMG has an extremely low instantaneous recovery property at a temperature below the freezing point, but the elastic fiber using the copolymerized PTMG has an instantaneous temperature which is almost the same as normal temperature even at a low temperature of -10 ° C. Shows resilience.

[0003] These properties are improved by using the copolymerized PTMG.
Is determined by the copolymerization ratio of the diol component, and the optimum copolymerization ratio corresponding to the industrial use thereof, generally, the copolymerization ratio of the diol component (hereinafter abbreviated as copolymerization ratio) is 5.0 to 50.0. It is selected and used from copolymerized PTMG having mol%.

Japanese Patent Application Laid-Open No. Sho 60-203 discloses that a heteropolyacid can be used as a catalyst for the copolymerization reaction between THF and a diol.
633, JP-A-61-120830 and JP-A-61-123630. These publications describe the catalytic activity of the heteropolyacid and the heteropolyacid salt, but do not mention at all the setting and control of the copolymerization ratio of the obtained copolymerized polyether polyol. The basis of a method for obtaining a copolymerized PTMG having an optimum copolymerization rate with a high reproducibility and stably in accordance with various applications is to always set the reaction conditions constant and control the operation.

[0005] In the reaction in which the diol is incorporated into the polymer chain via an ether bond, water is generated, but it is necessary to remove more water than the amount consumed as the polymer terminal from the reaction system. Further, the catalytic activity of the heteropolyacid is preferably in a range containing not more than 15 molecules of water per 1 molecule of the heteropolyacid, and from this point too, it is necessary to remove excess water in the reaction system outside the system.

For example, Japanese Patent Application Laid-Open No. 5-32775 discloses NP
Disclosed is a method for producing a copolymerized polyether polyol comprising reacting G and THF in the presence of an alcoholic hydroxyl group under a catalyst exhibiting activity, and proposes that heteropolyacid is one of effective catalysts. In addition, it is proposed that water generated by the reaction of NPG be removed as gaseous phase moisture in the reaction system, and the THF removed at the same time be replenished with fresh THF. That is, the publication proposes setting the reaction temperature to the boiling temperature of the reaction solution and controlling the THF replenishment rate so as to maintain the temperature. However, it is practically difficult to stably obtain a polymer having a predetermined copolymerization ratio by the method disclosed in the publication. Generally, as the reaction proceeds, the polymer concentration in the reaction system increases, and the boiling temperature of the reaction system rises. Therefore, in order to maintain the boiling temperature at a predetermined temperature, T
It is necessary to increase the supply amount of HF and suppress the rise in boiling point. Therefore, the composition of the reaction solution changes, and the amount of the reaction solution in the system also increases. That is, in this reaction, the liquid level at the end of the reaction is higher than that at the beginning of the reaction, and the ratio of the two layers in the reaction solution comprising the catalyst layer and the THF layer also changes greatly.
A slight change in the reaction behavior or operation management greatly affects the reaction conditions, and the copolymerization rate of the obtained copolymerized polyether polyol fluctuates.

The gas phase moisture of the reaction system is usually 0.4 to
2.0 wt. % And the remaining component is THF,
The distillate removed outside the reaction system is mainly composed of THF. The distillate amount is usually 2.0% of the initial THF charge amount.
１５15.0 wt. Twice as much, and more THF must be replenished, requiring excess equipment for distillate storage and preparation of replenished THF. This distillate amount increases as the copolymerization rate increases and the amount of generated water increases,
Production of a copolymerized PTMG having a high copolymerization rate requires a large storage tank facility. According to the method proposed in this publication, it is difficult to produce a copolymerized PTMG having a predetermined copolymerization rate in an industrially stable and inexpensive manner.

[0008]

DISCLOSURE OF THE INVENTION The present invention relates to a process for preparing a copolymer P by reacting a THF with a diol using a heteropolyacid as a catalyst.
An object of the present invention is to provide a method for producing a copolymerized PTMG having a predetermined copolymerization ratio when producing TMG.

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to a PTMG copolymer from THF and a diol using a heteropolyacid as a catalyst.
In the production of, a part of the content was continuously withdrawn from the reaction tank and separated into two layers. Then, the lower layer liquid was returned to the reaction tank, and the upper layer liquid was vaporized together with THF to evaporate the contained water and distilled out of the system. A copolymerized PTM, wherein the distillate is returned to the reaction tank after the reaction, and the distillate distilled out of the system is returned to the reaction tank after removing water.
G is a manufacturing method.

In the copolymerization of THF and a diol using a heteropolyacid as a catalyst, the reaction solution is stirred to make the reaction uniform. At this time, the reaction system forms a solution in which two layers, a THF layer containing a polymer and a catalyst layer, are dispersed in an emulsion state. In the polymerization of PTMG using a heteropolyacid as a catalyst, the polymerization reaction proceeds in the catalyst layer, and a polymer having a high molecular weight among the produced polymers is more easily distributed to the THF layer, and the growth is stopped there (catalyst, vo).
l. 30, no. 1, 34 (1991)). It is considered that the reaction also proceeds in the catalyst layer in the copolymerization of the present invention. Some of the water generated by the diol reaction is also consumed at the polymer terminals,
The remainder is distributed to the THF layer and the catalyst layer.

[0011] The amount withdrawn from the reaction tank is 1% of the reaction liquid in the tank.
It is sufficient that / 20 to 1/2 are always replaced. If the withdrawal amount is less than 1/20, removal of the water produced by the NPG reaction outside the system is delayed, and the polymerization reaction takes time. 1
If the ratio exceeds / 2, the replacement of the catalyst layer in the reaction tank is too large, and the polymerization reaction takes time.

The reaction liquid extracted from the reaction tank is transferred to a layer separator such as a decanter, whereby a lower catalyst layer having a higher specific gravity and a lower THF layer having a lower specific gravity are separated. In the present invention, the lower layer solution is returned to the reaction tank, the upper layer solution is sent to an evaporator or a still, and the water content in the solution is reduced to TH.
The remaining liquid is returned to the reaction tank by vaporization together with F, and the distillate is returned to the reaction tank after removing water in the liquid. Since the reaction solution is constantly withdrawn from the reaction tank, a continuous system is indispensable for the layer separator and the distillate remover for vapor-phase moisture and THF. Distillation may be performed under normal pressure or reduced pressure.

In the present invention, the reaction liquid extracted from the reaction tank is returned to the reaction tank in a state where the gas phase water in the THF layer has been removed. Therefore, the catalyst composition of the reaction system does not change, and the THF and diol compositions of the reaction system including the THF and diol units in the polymer chain are kept constant during the reaction.

In the present invention, since a place where the reaction proceeds and a place where the gas phase moisture is distilled off are separated, the reaction temperature can be arbitrarily selected irrespective of the distillation temperature. That is, the reaction temperature can be independently maintained at a constant level.

In the present invention, the composition ratio of THF and diol in the reaction system can be kept constant, and the reaction temperature can be kept constant. Therefore, the copolymerization ratio can be determined from the conversion ratio of each composition into a polymer. That is, by setting the charged amount of each raw material corresponding to the target copolymerization rate, it is possible to always produce a copolymerized PTMG having a constant copolymerization rate.

Further, the present invention provides a method for removing TH from a reaction system.
Since all the F is returned to the reaction system, there is no need to prepare new THF at all. Equipment for removing water from a mixture of water and THF is required, but the distillate is continuously treated, so that the purpose can be sufficiently achieved with relatively small equipment, and the capital investment is reduced. In addition, it is extremely advantageous in terms of management and operation amount.

As a method of removing water from a mixture of water and THF applicable to the present invention, for example, a method using an adsorbent such as molecular sieves or activated alumina, a method having a boiling point lower than the azeotropic composition of THF and water, and the like. A method of removing water by azeotropic distillation by adding an entrainer that creates an azeotropic composition with water,
A combination method of high-pressure distillation and low-pressure distillation utilizing the fact that the azeotropic composition of THF and water changes with pressure, an extractive distillation method utilizing addition of an appropriate solvent to eliminate the azeotrope of THF and water, A membrane separation method using a membrane selectively permeating only water or only THF can be considered. In particular, the above-mentioned method using an adsorbent such as molecular sieves, activated alumina and the azeotropic composition of THF and water are considered. It is convenient to add an entrainer to form an azeotropic composition with water having a low boiling point and remove water by azeotropic distillation.

In the adsorption method using an adsorbent such as molecular sieves or activated alumina, water can be adsorbed and removed only by bringing the distillate into contact with these adsorbents, so that it can be dealt with only by adding small and simple equipment. In particular, molecular sieves are advantageous in the practice of the present invention because they have high water adsorption capacity and can be easily regenerated.

The form of the above-mentioned adsorbent may be any of powder, granular, lump, and molded. Since the surface area required for normal adsorption becomes large, it is preferable to use one having a relatively small particle size. However, in consideration of the simplicity of handling and the pressure loss at the time of filling and using an adsorber such as a column, a tower or a tank, a granular material having a diameter of about 1 to 10 mm is practical.

As the adsorption treatment method, there is applied a continuous ordinary method in which a mixture of water and THF continuously distilled from the reaction system is sent to an adsorber filled with molecular sieves. The adsorption treatment temperature is not particularly limited, and the distillate may be directly introduced into the adsorber at that temperature.

The adsorbent which has lost its adsorption capacity is 100
By recirculating an inert gas, for example, a nitrogen gas, a carbon dioxide gas, or the like, heated to 300 ° C., the adsorption capacity can be recovered, and the gas can be used again as an adsorbent.

The present inventors have conducted various studies on an entrainer that forms an azeotropic composition with water at a low boiling point.
Normal pentane, cyclopentane, methyl-t-butyl ether, etc., under normal pressure, are 10 points higher than the azeotropic point of THF and water.
It was found that an azeotropic composition lower than ℃ was formed. When these entrainers are added and sent to a multi-stage distillation column, azeotropic components of water and the entrainer are added to the low boiling point, and THF is added to the high boiling point.
Can be recovered, and the recovered THF can be returned to the reaction system. The azeotropic composition liquid on the low boiling point side may be separated into two layers, and the entrainer may be reused, and water may be removed and disposed. Normal pentane and cyclopentane have low compatibility with water and very good layer separation, and can be conveniently used as an entrainer in the present method.

Specific examples of the diol having 2 to 10 carbon atoms in the present invention include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, 1,6 -Hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,8-octanediol, 1,10-decanediol, diethylene glycol, triethylene glycol, dipropylene glycol and the like. Neopentyl glycol is particularly preferable from the viewpoint of low-temperature characteristics, hysteresis loss, instant recovery, etc. of an elastic body using copolymerized PTMG as a soft segment, specifically, polyurethane fibers.

The heteropolyacid in the present invention is Mo,
At least one oxide of W and V, and other elements;
For example, P, Si, As, Ge, B, Ti, Ce, Co
And the like. The atomic ratio of the former to the latter is 2.5 to 12, especially 1
Two or nine are preferred.

Specific examples of these heteropoly acids include phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdung tungstovanadic acid, phosphorus tungstovanadic acid, phosphomolybdniobate, Silicotungstic acid, Silicomolybdic acid, Silicomolybdotungstic acid, Silicomolybdo tungstovanadic acid, Germanium tungstate, Bortungstic acid, Borolybdate acid, Borolybdotungstic acid, Borolybdovanadic acid, Borolybdotangustovanadine Acid, cobalt molybdate, cobalt tungstate, arsenic molybdate, arsenate tungstate, titanium molybdate, cerium molybdate, and the like. The type of the salt of the heteropolyacid is not particularly limited, but may be, for example, Li, Na, K, Rb, Cs, Cu,
Group I of the periodic table such as Ag and Au, Mg, Ca, Sr, B
a, Zn, Cd, Group II such as Hg, Sc, La, Ce, A
III, Group III such as Ga, In, and Fe, Co, Ni, R
u, Pd, Pt, and other Group VIII metals; Sn, Pb, Mn, Bi, and other metal salts; or ammonium salts, amine salts, and the like.

The amount of the heteropolyacid to be used is not particularly limited.
The weight is preferably 0.1 to 20 times the weight of the total amount of THF and diol.

The polymerization temperature may be 30 to 90 ° C., and the time required for the reaction may vary depending on the copolymerization rate, the amount of catalyst, the reaction temperature and the rate of removing water from the reaction system.
It takes about 5 to 50 hours. The internal pressure of the reaction system is not particularly limited, and it can be carried out at any of normal pressure, reduced pressure, and increased pressure.

The polymerization reaction proceeds in a catalyst layer while stirring THF, a diol and a heteropolyacid, and the separated T
Since it can be carried out while removing excess water generated by the reaction from the HF layer, a solvent is not particularly required, but a solvent inert to the reaction may be added in some cases.

The polymerization reaction can be carried out either in a batch system or a continuous system.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to the following examples.

Example 1 Polymerization was carried out using a polymerization reactor shown in FIG. A reactor (1) equipped with a stirrer, a reflux condenser and a hot water jacket was charged with 20.0 kg of THF and NP.
Charge 1.7kg of G, then 12-Tangst-1-
Phosphate dihydrate _{(H 3 PW 12 O 40 /} 2H 2 O) 13.0k
g was added. The hot water jacket was set at 70 ° C., the reaction solution temperature was controlled at 65 ° C., and the reaction was started with stirring under normal pressure. One hour after the start of stirring, a part of the reaction solution was continuously withdrawn from the bottom of the reactor (20 L / hour), sent to a decanter (2), and separated into two layers. The lower layer liquid was returned to the reactor, and the upper layer liquid was sent to an evaporator (3) equipped with a liquid level gauge.
Vapor-phase moisture was distilled together with THF at 0 mmHg and 63 ° C. Since the upper layer liquid was continuously sent from the decanter to the evaporator, the liquid level of the evaporator was kept constant, and the excess liquid was withdrawn as residual evaporation liquid and returned to the reactor. The distillate from the evaporator is a type 3A molecular sieve, an adsorption tower (4) packed with 10 kg (diameter 135 mm, height 950 m)
m), sent to the lower part of the column, withdrawn from the upper part of the column, and returned to the reactor. The adsorption tower used was previously filled with pure THF. The water in THF in the adsorption tower is 3,0
00 to 5,000 ppm, and that of the adsorption tower is 10
It was 0 to 200 ppm. In addition, the temperature of the reaction solution in the reaction vessel changed at 65 ± 1 ° C. After 12 hours, the reaction was terminated,
The hot water jacket was lowered to 45 ° C., allowed to stand, separated into two layers, and the upper layer liquid was removed. About 200 ml was taken from the upper layer solution, and calcium hydroxide was added to precipitate a small amount of the contained catalyst, followed by filtration. Subsequently, THF in the filtrate was removed by evaporation to obtain a transparent and viscous polymer. The resulting polymer is
As a result of ¹ H-NMR (400 MHz) measurement,
It was a copolymerized PTMG having 12.5 mol%.

Using this apparatus, polymerization was further repeated four times. The copolymerization rates of the obtained polymers were respectively 12.
5, 12.3, 12.6, 12.4 and ¹ H-NM
Copolymerized PTM having the same copolymerization ratio within the measurement accuracy of R
G.

(Comparative Example) In this example, vapor-phase moisture was distilled out of the reactor together with THF, trapped, and fresh THF was supplied to the reactor according to the amount of the distilled-out THF, and the reaction temperature was maintained. did. In a reaction vessel equipped with a stirrer, a distiller and a THF feeder, 460 g of THF and 40 g of NPG were added.
Charge, followed 12 tungstosilicic 1-phosphate dihydrate _{(H 3 PW 12 O 40 /} 2H 2 O), was added 300 g. The heating bath temperature was adjusted so that the reaction solution temperature became 70 ° C., and stirring was started. While distilling THF containing water vapor from the reactor, fresh THF was supplied to the reactor to maintain the temperature of the reaction solution at 70 ° C., and the reaction was carried out for 12 hours. The reaction volume at the end of the reaction was about 200 ml larger than at the start of the reaction.

As a result of ¹ H-NMR measurement in the same manner as in Example 1, the copolymerization ratio of the polymer was 10.1 mol%. Further, polymerization was repeated four times. The copolymerization rates of the obtained polymers were 12.0, 7.6, 9.7, respectively.
8.9, and the copolymerization rate varies greatly from reaction to reaction.
Problems with reproducibility

[0035]

According to the present invention, the place where the reaction proceeds and the place where the vapor-phase moisture is distilled off can be separated, and the catalyst, raw material composition and reaction temperature during the reaction can be kept constant. In addition, it is possible to stably produce a copolymerized polyether polyol having a small variation in the copolymerization rate, and efficiently produce a copolymerized polyether polyol having a copolymerization rate corresponding to the intended use.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a reaction apparatus used in Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor 2 Decanter 3 Evaporator 4 Adsorption tower

Claims (1)

[Claims] In producing a copolymerized polyether polyol from tetrahydrofuran and a diol having 2 to 10 carbon atoms using a heteropolyacid as a catalyst, a part of the content is continuously withdrawn from a reaction tank and separated into two layers. After separation
The lower layer liquid was returned to the reaction tank, the upper layer liquid was vaporized together with tetrahydrofuran to evaporate out of the system and then returned to the reaction tank, and the distillate distilled out of the system was removed to remove water and then returned to the reaction tank. A method for producing a copolymerized polyether polyol.