JP3533851B2 - Cyclic ether polymerization method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyoxyalkylene glycol ester by ring-opening polymerization of a cyclic ether with a carboxylic acid anhydride in the presence of a catalyst. More specifically, it is intended to provide a method for polymerizing a cyclic ether, which can be applied to a method for industrially advantageously producing a polyoxyalkylene glycol while suppressing a decrease in activity of the catalyst by using a catalyst with which the catalyst can be easily separated. It is a thing.

[0002]

2. Description of the Related Art Polyoxyalkylene glycol has the general formula HO-[(CH ₂ ) _n O] _m -H (m is an integer of 2 or more, n
Represents an integer of 1 or more) and is a linear polyether glycol having primary hydroxyl groups at both ends, and is generally produced by ring-opening polymerization of a cyclic ether. Of these, polyoxytetramethylene glycol (PTMG) obtained by a polymerization reaction of tetrahydrofuran (THF) has a particularly industrial meaning. PTMG is linear polyether glycol having primary hydroxyl groups at both ends, the general formula _{HO - [(CH 2) 4} O] p -H (p is 2 or more,
It is an integer of 4000 or less), and a medium molecular weight polymer used as a raw material for urethane-based elastic fibers that are required to have elasticity and elasticity is industrially used.

Recently, it is also used as a raw material for thermoplastic elastomer materials. For use as a raw material for such elastic fibers and elastomer materials, PT having a medium molecular weight of about 500 to 3,000 in number average molecular weight (Mn) is used.
MG is used. As one of the methods for synthesizing such PTMG, Japanese Patent Application Laid-Open No. 4-306228 and Japanese Patent No.
No. 208,385, SiO _2-
Using a complex oxide such as Al ₂ O ₃ as a catalyst, THF is subjected to a polymerization reaction in the presence of an acid anhydride to obtain polyoxytetramethylene glycol diester (PTME) having both ends esterified. A method for obtaining PTMG by an alcoholysis reaction or the like has been proposed. Further, US Pat. No. 5,344,964 and Japanese Patent Publication No. 6-505515 disclose a method of coexisting an acid anhydride and an acid in order to control the molecular weight or increase the reaction rate in this reaction. However, the ratio of acid to acid anhydride is high.

Further, in these methods, the catalyst can efficiently produce PTME having a number average molecular weight of about 500 to 4,000 in an initial performance with a relatively narrow molecular weight distribution. Continuously use PTM
When trying to produce E, the activity is significantly reduced. Therefore, it is impossible to continuously and industrially produce PTME for a long period of time, and it is difficult to say that it is an industrially useful method.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for continuously and industrially producing an ester of polyoxyalkylene glycol by ring-opening polymerization of a cyclic ether.

[0006]

Generally, a polymerization reaction of a cyclic ether in the presence of a carboxylic acid anhydride is carried out by a nucleophilic reaction of a cyclic ether to a carboxylic acid anhydride activated at a Lewis acid site. The mechanism is that the reaction is initiated, the reaction proceeds by chain growth of cyclic ether, and the reaction is stopped by an electrophilic reaction to acetate or the like. That is, a Lewis acid type catalyst is effectively used as the catalyst. For example, complex oxides, aluminum chloride, clay compounds, zeolites, etc. are known to have Lewis acid points as acid points (metal oxides and complex oxides, edited by Kozo Tabe, etc.). The present inventors have noted that when the Lewis acid site is the active site, the property of the Lewis acid is that water poisons the active site of the catalyst and impairs the polymerization activity.

In particular, the starting material, cyclic ether itself, often contains water. For example, butadiene is oxidatively acetoxylated and then hydrolyzed to form 1,4-butanediol. In the production process of obtaining tetrahydrofuran by dehydration, water derived from hydrolysis and dehydration reactions is mixed in with the product tetrahydrofuran. The amount of water mixed in this case is at most several hundred p
At the pm level, this is sufficient to degrade the Lewis acid catalyzed polymerization reaction over time.

The inventors of the present invention have made extensive studies as a countermeasure against such catalyst deterioration. As a result, a protic acid having a molar ratio of 1/16 to 1 / 30,000 with respect to a carboxylic acid anhydride is dissolved in the reaction system. It was found that it is extremely effective to carry out the ring-opening polymerization reaction under the conditions existing in. When the protic acid is present in a dissolved state, it is considered that it is adsorbed on the catalyst in preference to water and prevents the adsorption of water, so that the polymerization activity can be prevented from lowering even in the presence of several hundred ppm of water.

That is, the gist of the present invention is to carry out a ring-opening polymerization reaction of a cyclic ether with a solid acid polymerization catalyst in the presence of a cyclic ether and a carboxylic acid anhydride so that some or all of the terminals of the polymer are In the method for obtaining an esterified polymerized composition, the molar ratio to the carboxylic acid anhydride is 1/16.
The present invention resides in a method for polymerizing a cyclic ether, characterized in that the polymerization reaction is carried out under the condition that ˜1 / 30,000 protic acid is dissolved and present in the reaction system.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, examples of the cyclic ether used as a reaction raw material include those having 2 to 10 carbon atoms in the ring, and specifically, THF, ethylene oxide, propylene oxide and oxetane. , Tetrahydropyran, oxepane, 1,4-dioxane and the like are used. Further, a cyclic ether substituted with an alkyl group such as 2-methyltetrahydrofuran or a halogen atom can also be used. Among these, especially THF is P
Since it is a raw material of TMG, it is industrially important and suitable as a cyclic ether as a raw material of the polymerization method of the present invention. These reactants may contain water at levels of several hundred ppm.

As the polymerization catalyst having the Lewis acidity as described above, it is preferable to use the solid acid polymerization catalysts exemplified below. a) {Ge, Sn, Pb, B, Al, Ga, Zn, C
d, Cu, Fe, Mn, Ni, Cr, Mo, W, Ti,
Catalyst b in which one kind and / or two or more kinds of oxides selected from the group consisting of Zr, Hf, Y, La, Ce, Yb, Zn, Si} are calcined at a high temperature of about 600 ° C to 1100 ° C. ) Clay compounds containing Si and Al, for example, clay compounds such as montmorillonite, saponite, sepiolite and mica

C) BEA, EMT, ERI, EUO,
FAU, HEU, LTA, LTL, MAZ, MOR, M
Zeolites with a structure selected from the group consisting of TW, NES, OFF, and TON (Structure Commi
session of the International
Zeolite Association's "ATL
AS OF ZEOLITE STRUCTURE T
YPES, Third Edition (199
2), W. M. Meier and D.M. H. Ols
on description) and the like.

These may be used alone or in combination of two or more. Industrially useful PTMG
Many have a number average molecular weight in the range of about 500 to 4,000, but this number average molecular weight tends to depend on the acid strength of the Lewis acid. That is, when the Lewis acid strength is high, the number average molecular weight decreases. It is known from the theory of Tabe ("Metal oxide and complex oxide" edited by Kozo Tabe, etc.) that the Lewis acid strength is defined by the combination of metals. Therefore, in order to obtain PTMG having a desired number average molecular weight, the acid strength is selected from the above a), b) and c) and has a specific acid strength (using Hammet's indicator, H ₀ (acid point by Hammet's acidity function). Strength) ≤ +3.3, preferably H
A catalyst having ₀ ≦ −3.0) may be used.

In the present invention, as the Lewis acid type catalyst as the solid acid polymerization catalyst, an oxide or complex oxide of the specific metal of the above (a) (hereinafter simply referred to as "complex oxide") is used. Preference is given to using. As this manufacturing method,
{Ge, Sn, Pb, B, Al, Ga, Zn, Cd, C
u, Fe, Mn, Ni, Cr, Mo, W, Ti, Zr,
By optionally adding an acid, an alkali, or water to a mixed solution containing a salt of two or more kinds of metals selected from the group consisting of Hf, Y, La, Ce, Yb, Zn, Si} or an alkoxide thereof. A precipitate or gel is formed as a polymerization catalyst precursor. Examples of the method for obtaining a precipitate or gel include a coprecipitation method, a sol-gel method, a kneading method and an impregnation method. A method for obtaining a polymerization catalyst precursor through a process of supporting a metal salt / or metal alkoxide on a suitable carrier and contacting a basic substance such as alkali or amine in a solid state (substantially free of water) Is particularly effective.

The polymerization catalyst precursor thus obtained is filtered, washed and dried, if necessary, and then nitrogen,
The desired (composite) oxide can be obtained by firing in an inert gas atmosphere such as argon or an oxidizing gas atmosphere such as air or diluted oxygen gas. The heating and firing temperature is usually 600 to 1150 ° C., preferably 600 to 1000.
It is performed at a high temperature of ℃. The high temperature calcination improves the activity and stability of the catalyst.

The carboxylic acid anhydrides used in the present invention are preferably those derived from poly and / or monocarboxylic acids having 2 to 12, preferably 2 to 8 carbon atoms, which are aliphatic or aromatic. Used.

For example, with an anhydride of an aliphatic carboxylic acid,
Acetic anhydride, butyric anhydride, propionic anhydride, valeric anhydride,
Examples thereof include caproic anhydride, caprylic anhydride, and pelargonic anhydride.Anhydrides of aromatic carboxylic acids include phthalic anhydride and naphthalic anhydride, and aliphatic polycarboxylic acids include succinic anhydride and maleic anhydride. can give. Among these carboxylic acid anhydrides, acetic anhydride is particularly preferable in view of its effect, price and availability. The carboxylic acid anhydride is usually 0.01 to 1.
It is preferable to add it in the range of 0 (molar ratio). Polyoxyalkylene glycols produced using this acid anhydride form esters with this acid anhydride, namely PTMG
Since it is obtained as an ester (PTME) with this acid anhydride, a means such as hydrolysis or alcoholysis is required to convert this PTME into PTMG.

The protonic acid used in the present invention is soluble in the reaction system and is preferably an organic acid or an inorganic acid. For example, organic acids include carboxylic acids, sulfonic acids, and phenols, and inorganic acids include sulfuric acid, hydrochloric acid, phosphoric acid, and the like. A carboxylic acid is preferably used.

The carboxylic acid used in the present invention is preferably 2 to 12, preferably 2 to 8 aliphatic or aromatic.
Those selected from poly and / or monocarboxylic acids having 4 carbon atoms are used.

For example, among aliphatic carboxylic acids, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid,
Examples include pelargonic acid and the like, examples of the aromatic carboxylic acid include phthalic acid and naphthalene carboxylic acid, and examples of the aliphatic polycarboxylic acid include succinic acid, maleic acid and fumaric acid. Among these carboxylic acids, acetic acid is particularly preferable in view of its effect, price and availability. Carboxylic acid is usually 1/16 in molar ratio with respect to carboxylic acid anhydride.
It is good to exist in the range of 1 / 30,000. If the concentration is lower than this, the effect of the presence of carboxylic acid is small, and if the concentration is higher than this, elution of the polymerization catalyst component, increase of separation / recovery load by distillation, decrease in initial activity, corrosion of reactor, etc. It has an adverse effect and is not preferable in terms of quality and economy. If desired, the ester produced by the reaction with the carboxylic acid may be converted into PTMG by hydrolysis, alcoholysis, or the like.

A solvent may be used in the polymerization reaction of the present invention. As the solvent, it is also possible to use aliphatic hydrocarbons, aromatic hydrocarbons, hydrocarbons containing a hetero atom such as nitrogen, sulfur, oxygen and halogen, which are inert to ring-opening polymerization.

As the reaction system, a generally used one such as a tank type or a tower type is used, and either a batch system or a continuous system may be used. Specifically, a method in which a cyclic ether and a catalyst are charged into a reactor and carboxylic acid anhydride and a protonic acid are charged and polymerized with stirring (batch method), a reaction including a cyclic ether and a carboxylic acid anhydride, a protonic acid, and a catalyst Any method (continuous method) of continuously supplying the charged composition liquid to the reactor and continuously withdrawing the reaction liquid may be used. The effect of the present invention is great when the catalyst is used continuously or intermittently for a long time with respect to the supply of the substrate.

The amount of the polymerization catalyst used is determined according to the kind of the catalyst and is not particularly limited. For example, in a batch reactor, if the amount of the catalyst is too small, the polymerization rate becomes slow, and conversely if it is too large. However, it becomes difficult to remove the heat of polymerization. Further, since the slurry concentration in the reaction system becomes high, stirring becomes difficult, and a problem easily occurs in liquid separation between the catalyst and the reaction liquid after completion of the polymerization reaction. In particular, when the (composite) oxide polymerization catalyst of the above a) is used, it is usually 0.0 with respect to the liquid phase.
It is selected from the range of 01 to 50 times by weight, preferably 0.01 to 20 times by weight, in consideration of the reaction forms of batch reaction and flow reaction. However, in the case of a flow reaction, this usage amount represents the amount of the catalyst with respect to the supply amount of the liquid phase per unit time.

The reaction temperature is usually 0 to 200 ° C, preferably 10 to 80 ° C. The reaction pressure may be any pressure as long as the reaction system can maintain a liquid phase, and is usually atmospheric pressure to 10M.
Pa, preferably selected from the range of pressure from normal pressure to 5 MPa. The reaction time is not particularly limited, but in consideration of both the amount of catalyst and the yield of PTME and economic efficiency, it is 0.1
-20 hours, preferably 0.5-15 hours. The reaction time here means the time from the time when the reaction temperature is raised to the time when the reaction is completed and cooling is started in the batch system, and in the continuous system,
It refers to the residence time of the reaction composition liquid in the reactor.

The molecular weight distribution of the polymer produced by the method of the present invention depends on the type of cyclic ether, but when THF is polymerized, for example, the number average molecular weight of 200 to 8 is obtained.
It is possible to obtain PTMG having a low to medium molecular weight of about 10,000, particularly about 200 to 40,000. Another feature is that PTMG having a narrow molecular weight distribution can be easily produced. That is, Mw / Mn is less than 20, for example, 1.0-1
It is possible to produce PTMG of 0.0 and Mw / Mn of which industrial demand is great is 1.0 to 4.0, more preferably 1.1 to 3.0, and especially Mw is selected by selecting preferable conditions of the present invention. / M
PTM with a very narrow molecular weight distribution where n is 1.1 to 2.0
G can also be obtained. Therefore, according to the present invention, the number average molecular weight of 500 to 3, which is industrially extremely useful, is high.
000, especially 700 to 2,000, Mw / Mn of 1.1
It is possible to produce PTMG having a relatively low molecular weight of ˜3.0, particularly 1.1 to 2.0, and a very narrow molecular weight distribution.

As described above, in the present invention, it is preferable to use the (composite) oxide of a) as the solid acid-based polymerization catalyst, but the characteristic of this catalyst system is the step of recovering unreacted cyclic ether and carboxylic acid. , And easy removal of the obtained polymer and regeneration of the catalyst. For example, in the case of a batch reaction system, after the reaction is completed, the catalyst and the reaction solution are first filtered and separated, and the reaction solution is separated into unreacted cyclic ether,
After distilling off the carboxylic acid anhydride and the carboxylic acid, only the polymer can be easily obtained. Furthermore, the catalyst after the reaction can be easily washed and then the activity can be easily recovered by burning the attached organic matter.

[0027]

The present invention will be described in more detail based on the examples of the present invention, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following examples, reaction time, Mn, Mw, yield and φ / φe have the following meanings.

Reaction time: The reaction is initiated when the reactor is immersed in a water bath set to a predetermined reaction temperature. Yield (φ): wt% of PTMG acetate with respect to the supplied THF (the time in parentheses after “φ” represents the reaction time, that is, “φ (Xhr)” is the yield after X hours) Mn: Gel Permeation Chroma
Number average molecular weight measured by tography. Mw: Gel Permeation Chroma
Weight average molecular weight measured by tography. Mw
/ Mn (Xhr) represents Mw / Mn after X hours. Equilibrium yield (φe): Equilibrium yield of acetic acid ester of PTMG at that temperature ([Chemical Dojin, Ring-Opening Polymerization (1) Lecture, Polymerization Theory 6, Takeo Saegusa, first edition issued May 10, 1971] Calculated based on Figure 3.11 of p171 of the above.)

Example 1 (Preparation of polymerization catalyst) 50 g of a commercially available SiO ₂ carrier (product of Fuji Silysia Chemical Ltd., trade name: Carryact Q-15, 10-20 mesh) was added to zirconium oxynitrate dihydrate 1.7.
g, tetraethyl silicate 9.1 g and urea 5.7 g
It was immersed in 70 ml of a methanol solution in which was dissolved. After distilling off the solvent methanol at 60 ° C under reduced pressure, the solid obtained was heated to 120 ° C for 1 hour and then to 800 ° C over 2 hours and 30 minutes under air flow, and kept at 800 ° C for 3 hours. And then cooled. The amount of ion-exchanged acid in this ZrO ₂ —SiO ₂ catalyst was 0.005 mmol / g.

(Polymerization reaction) ZrO prepared in this way
_{The 2-} SiO ₂ oxide catalyst was filled in a tubular reactor, the reaction temperature was 40 ° C., and tetrahydrofuran / acetic anhydride / acetic acid = 1 /
0.0175 / 0.0010 (molar ratio), LHSV = 1
The reaction was carried out at (hr ^-1 ). The rate of decrease in the conversion rate (φ) of tetrahydrofuran is expressed as the activity retention rate (%) = φ (200 hr) / φ (20 h
r) × 100, and the extent of the spread of the molecular weight distribution is the deterioration rate of the molecular weight distribution = {Mw / Mn (200 hr)} / {Mw / Mn (20
hr)}, the values of activity retention rate = 72% and molecular weight distribution deterioration rate = 1.04 were obtained.

Comparative Example 1 (Polymerization reaction) ZrO ₂ —Si prepared in the same manner as in Example 1
The O ₂ oxide catalyst was filled in a tubular reactor and the reaction was carried out with THF / acetic anhydride = 1 / 0.0180 (molar ratio). As a result of this reaction, activity retention rate = 48%, molecular weight distribution deterioration rate =
It was a value of 1.11.

Example 2 (Polymerization reaction) ZrO ₂ -Si prepared in the same manner as in Example 1
The O ₂ oxide catalyst was placed in a flask equipped with a reflux condenser,
Catalyst / tetrahydrofuran = 0.035 (weight ratio), tetrahydrofuran / acetic anhydride / acetic acid = 1 / 0.035 /
It was charged at 0.002 (molar ratio) and reacted at a reaction temperature of 40 ° C. for 5 hours with stirring. The yield was 27%, Mw /
Mn was 1.9.

Comparative Example 2 (Polymerization reaction) As in Example 2, catalyst / tetrahydrofuran = 0.035 (weight ratio), tetrahydrofuran / acetic anhydride / acetic acid = 1 / 0.024 / 0.024 (molar ratio)
When the reaction was carried out in, the yield was as low as 18% and M
w / Mn increased to 2.0.

[0034]

INDUSTRIAL APPLICABILITY According to the present invention, in a method for producing an ester of polyoxyalkylene glycol by subjecting a cyclic ether to ring-opening polymerization with a carboxylic acid anhydride in the presence of a catalyst, a catalyst that can be easily separated is used. The present invention provides a method for producing a polyoxyalkylene glycol having a low molecular weight and a narrow molecular weight distribution, which is industrially advantageous by suppressing a decrease in activity of the catalyst.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-73586 (JP, A) JP-A-8-231706 (JP, A) JP-A-60-163922 (JP, A) JP-A-7- 62081 (JP, A) JP 62-252422 (JP, A) JP-B 43-9527 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 65/329-65 / 337 C08G 65/20

Claims (7)

(57) [Claims] 1. A solid acid-based polymerization catalyst selected from the following :
In a method of ring-opening polymerization of a cyclic ether in the presence of a carboxylic acid anhydride to obtain a polymerized composition in which some or all of the terminals of the polymer are esterified, a molar ratio of 1 to the carboxylic acid anhydride is obtained. A method for polymerizing a cyclic ether, wherein the ring-opening polymerization reaction is carried out in a reaction system in which / 16 to 1 / 30,000 protic acid is dissolved and present . Solid acid polymerization touch
Medium: Ge, Sn, Pb, B, Al, Ga, Zn, Cd,
Cu, Fe, Mn, Ni, Cr, Mo, W, Ti, Z
r, Hf, Y, La, Ce, Yb and Si
Oxides and complex oxides of two or more of these elements
A Lewis acid. 2. The solid acid polymerization catalyst is a metal salt or
From the solution containing lucoxide to the carrier, the metal salt or
It was prepared through the step of supporting lucoxide.
Polymerization of the cyclic ether according to claim 1, characterized in that
Method. 3. A reactor filled with a solid acid polymerization catalyst,
Includes cyclic ethers, carboxylic acid anhydrides and protic acids
A contract characterized by carrying out a ring-opening polymerization reaction by circulating a liquid.
The method for polymerizing a cyclic ether according to claim 1 or 2. 4. A solid acid polymerization catalyst and a cyclic ether in a reactor.
Under stirring.
A contract characterized by carrying out a ring-opening polymerization reaction while refluxing
The method for polymerizing a cyclic ether according to claim 1 or 2. 5. A polymerization method of cyclic ethers as claimed in any one of claims 1 to 4, wherein the cyclic ether is tetrahydrofuran. 6. The annular according to any one of claims 1 to 5 carboxylic acid anhydride and wherein the acetic anhydride
Polymerization method of ether . 7. A cyclic Agent according to any one of claims 1, wherein the protonic acid is a carboxylic acid 6
Ter polymerization method.