JPS61115935A - Depolymerization of cyclic polyalkylene ether - Google Patents

Abstract

PURPOSE:To recover the constituent monomers of a low impurity content in good efficiency, by depolymerizing a cyclic polyalkylene ether produced as a by-product in the production of a polyalkylene ether by using a heteropolyacid (salt) as a catalyst. CONSTITUTION:A polyalkylene as a material for the production of polyurethane is produced by (co)polymerizing a cyclic ether such as an alkylene oxide or tetrahydrofuran. Oligomeric cyclic alkylene ethers contained as by-products in the polyalkylene are recovered by an operation such as extraction or distillation and a heteropolyacid (salt) is added thereto as a catalyst. The oligomer is depolymerized at a temperature of about 50-200 deg.C to recover the constituent monomers, which are recovered. Examples of the heteropolyacids (salts) include phosphomolybdic acid, borotungstic acid and their sodium and magnesium salts.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for depolymerizing a cyclic polyalkylene ether as a constituent monomer by depolymerizing the cyclic polyalkylene ether using a specific catalyst.

(Prior art) Polyalkylene ethers obtained by polymerizing or copolymerizing cyclic ethers such as alkylene oxide, oxetane, and tetrahydrofuran (hereinafter abbreviated as THF) are industrially important polymers used in the production of polyurethane, etc. It is. It is known that these polyalkylene ethers contain oligomeric cyclic ether by-products (J, IRose, J, Ohem, 8ocy).
542 (1956) e J-Dale, K.

]) arsratn, T. Gronneberg,
Makromol, Ohem, a 178 e8
73 (197?) e J, M, McKenna,
T., K., Wu, and G.

Pruckmayr # Macromolecule
s + 10 # A 4 * 877 (19???)
).

On the other hand, when such polymers are used in the production of polyurethanes, the presence of cyclic ether by-products tends to degrade the properties of the polyurethanes, similar to when Machiya agents are used.

It is known that these oligomeric cyclic alkylene thithyls can be removed by conventional extraction or distillation methods (D, G, 8tewart, D, Y
-Waddan, and E. T. Borrows,
Brlt, Pat, 785.2251 (1957
), Y., Arimatsu, J., Polym.
, 5ciersce part A 1.4.728
(1966), J.M., Andrevs and J.
A.

8tmlyen, Polymer, 12*64
2 (1971), I￥f Kaisho 54-145797
In order to reduce the manufacturing cost of polyalkylene ether, it is preferable to decompose the separated and recovered oligomeric cyclic alkylene thithyls into constituent monomers and reuse them.

As a catalyst for depolymerizing oligomeric cyclic ether,
Ion exchange resins (JP-A-50-75697, JP-A-54-145795) and montmorillonite clay (JP-A-55-795) are already known.

(Problems to be Solved by the Invention) However, each of these known depolymerization catalysts has drawbacks. In other words, ion exchange resin has a temperature close to the resin's usage limit (1
(20 to 150°C), and the activity deteriorates over time. Furthermore, montmorillonite clay does not have a sufficient depolymerization rate, and its activity deteriorates over time.

(Another Means to Solve the Problem) As a result of intensive research into catalysts that do not inhibit depolymerization activity, are highly active, and are less corrosive, the inventors have discovered a catalyst that satisfies these conditions. A heteropolyacid and its salt were discovered as a catalyst, and the present invention was completed.

That is, the present invention is a depolymerization method characterized by using a heteropolyacid or a salt thereof as a catalyst when depolymerizing a cyclic alkylene ether with a catalyst to obtain a constituent monomer.

The heteropolyacid or its salt as a catalyst used in the present invention is usually synthesized as a 20-40 hydrate. Even if it is brought into contact with oligomeric cyclic alkylene ether in this state, the depolymerization activity is extremely low, but as water is removed from the system by distillation, the activity becomes high, and the water utilization number becomes 15 or less for one molecule of heteropolyacid. In particular, when the number is 4 or less, the activity becomes high.

When a heteropolyacid is used in an anhydrous state, it has very high activity, but its activity deteriorates over time. Therefore, for long-term use, it is preferable to have a hydration number of 1 or more.
Therefore, it is preferable to control the reaction within a suitable range by adding or removing water.

In order to completely depolymerize the orisimeric cyclic ether into constituent monomers, it is necessary to carry out the reaction while removing the monomers from the reaction system by distillation or the like.

The cyclic alkylene ethers covered by the present invention include:
It means a compound containing an oxyalkylene group having the general formula +(OH!+-0→-(however, n≧1) in the ring, or an oxyalkylene group having a substituent such as an alkyl group or a halogenated alkyl group) Furthermore, when carrying out the method of the present invention, the cyclic alkylene ether may be in a mixed state with other organic substances.

When the cyclic alkylene ether is a mixture with a linear polyalkylene ether, the linear polyalkylene ether is also depolymerized to the constituent monomers under the same conditions.

A mixture of oligomeric cyclic alkylene ether and PTMG separated by a method such as extraction from polyoxytetramethylene glycol (hereinafter abbreviated as PTMG) obtained by polymerizing THF, THF and other cyclic ether or A mixture consisting of the polyether glycol and an oligomeric cyclic alkylene ether separated by a method such as extraction from the polyether glycol obtained by copolymerizing the polyether glycol with an alcohol is a suitable application example of the present invention. Further, it may be a mixture with an extraction solvent such as a hydrocarbon or a halogenated hydrocarbon.

The heteropolyacid in the present invention includes Mo, W, and V.
At least one oxide and another element, such as P, 8
i, As5Ge13. It is a general term for oxyacids produced by condensation of oxyacids such as Ti, Oe, and Oo, and the atomic ratio of the former to the latter is 2.5 to 12.

Specific examples of these heteropolyacids or salts thereof include phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungsten acid, phosphomolybdononadic acid, phosphomolybdothanum dust/nadic acid, phosphothanan dust nonadic acid,
/molybdoniobic acid, silicotungstic acid, silicomolybdic acid, silimolybdotungstic acid, silicomolybdotungstic acid, germanium tungstic acid,
borotungstic acid, boromolybdic acid, boromolybdotungstic acid, boromolybdononadic acid, boromolybdotangestononadic acid, conorthomolybdic acid,
These are conort tungstic acid, arsenic molybdic acid, arsenic tungstic acid, titanium molybdic acid, cerium molybdic acid, and salts thereof.

Examples of the salt include metal salts of Group I, Group II, Group II, Group III of the periodic table, and the like.

The amount of heteropolyacid used is not particularly limited, but if the amount of heteropolyacid in the reactor is small, the depolymerization rate will be slow, so 0.1% by weight or more of the cyclic ether or a mixture thereof with a chain polyalkyl ether is used. is preferable. Also,
If the amount of hetero-phosphoric acid is large, the range of acceptable water that may be present in the system will be widened, and the smaller the amount of coordinated water, the higher the activity.
It is preferable to use 50 weight x.

The reaction temperature is preferably 50 to 200°C, particularly 80 to 150°C. The depolymerization reaction is extremely slow below 50°C, and
At temperatures above 0.degree. C., there is a risk of oxidative decomposition of the cyclic or chain alkylene ether. However, when removing constituent particles or water from the system, if the reaction is to be carried out at a temperature that cannot be removed at normal pressure, the system should be reduced in pressure and the reaction t? Let's do it. The depolymerization reaction system is preferably kept in an inert atmosphere, especially under high temperature conditions, to prevent oxidation of the polyalkylene ether and constituent monomers.

The reaction can be carried out while stirring the cyclic alkylene/ether or a mixture of it and a linear polyalkylene ether and the heteropolyacid or its salt in the specified hydration water, so no particular solvent is required, but a solvent that is inert to the reaction can be carried out. You can also add something.

The Hanzhonghuang method can be carried out in either a patch method or a continuous method using a generally used reactor having a mixing and stirring function.

(Effects) The present invention is characterized in that the depolymerization rate is faster than that of conventional methods, and the deterioration of catalyst activity is small. Further, the monomer obtained by decomposition according to the present invention contains extremely few impurities such as peroxide, and can be reused as a polymerization raw material without the need for purification.

(Example) The present invention will be explained below with reference to Examples.

Example I Olibimeric cyclic polytetramethylene ether SOf, P'l'MG 50t, n-octane 10, which is produced as a by-product in THF O ring-opening polymerization and has the general formula 0%9)
Add the 0 f mixture to a three-way flask equipped with a stirrer, thermometer, and drain condenser. Then, silicotungstic acid was heated at 250°C for 3 hours to make it anhydrous (
H48tw1! Add o4.)31 and heat to 130°C while stirring. The depolymerization reaction immediately proceeds, and 1
In time, 98% of the oligomer circulating polytetramethylene ether and PTMG depolymerized to 'I'HF,
It leaked out of the system.

Examples 2-13 Mitsuro flasks similar to those described in Example 1 n≦6)
oligomer-like cyclic polytetramethane, lene ether s
31 of various heteropolyacids or their salts shown in Table 1, which have been made anhydrous by heating at a high temperature, are added. The mixture was heated to 130°C while stirring, and the outflow amount of THF was measured after 1 hour. The results are shown in Table-1.

Table 1 Example 14 Add 50 ft of the oligomer-like cyclic polytetramethylene ether described in Example 2 to a Mitsuro flask equipped with a stirrer, a reflux condenser, and a setting meter. To this, silicotungstic acid (H481Wuo
n-pH 10) Add 1.5 tf.

After stirring at 100° C. for 20 minutes, the conversion rate to THF was measured, and the initial depolymerization activity based on the number of coordinated waters (nlc) was compared.

The results are shown in Table-2.

Table 2 Example 15 In a Mitsuro flask equipped with a stirrer, thermometer, and condenser, oligomer-like cyclic 4-realkylene ether 50, which was produced as a by-product of the copolymerization reaction of THF and ethylene oxide, was placed. ? Add. Then, it was heated at 250°C for 3 hours,
Phosphortungstic acid (H3PW11) in anhydrous form
04＠ ) 3 f t: Add 1 while stirring.
Heat to 30°C. The decomposition reaction proceeded immediately, and 93% of the charged oligomeric cyclic polyalkylene ether was dissolved in 1 hour.
% was decomposed and THF distilled out of the system was recovered.

Example 16 1 f of anhydrous phosphotungstic acid catalyst is added to a four-piece flask equipped with a stirrer, a thermometer, a discharge condenser, and a feeder. While heating to 130°C and stirring, a mixed solution t- 2
0? The depolymerization reaction was carried out continuously by feeding the mixture into a four-tube flask at a rate of /hr. Although the reaction was carried out continuously for 50 hours, no deterioration of the catalyst activity was observed, and THF and water continued to be distilled out.

Patent applicant: Asahi Kasei Kogyo Co., Ltd. Procedural amendment (branch) March 1985 l? Japan Demand Agency Director General Shiga Gakudon 1, Printing display 1981 Tsunai Sacrificial Seaweed 237492 No. 2
, Title of the invention: Method for depolymerizing cyclic polyalkylene ether 3, Person making the amendment Relationship to the case Patent applicant: 1-2-6-4 Dojimahama, Kita-ku, Osaka-shi, Osaka Prefecture Date of amendment order: February 1985 6th (Shipping date 60.2.26) 5
, "Detailed Description of the Invention" column 6 of the specification subject to amendment, Contents of amendment (1), r J, B, R on page 2 of the specification, lines 2-6
ose + J, Chem.

5ociety 542 (1956) ・・・・・・
” should be corrected as follows.

[Journal of the Chemical Society No. 54
2 pages (1956) (Journal of the
Chemical 5ociety 542 (1956
)) + Macromolecular Hemi-vol. 178, p. 873 (1977) (Makroa+olecu
lare Chemie, 178.873 (1977)
), Macromolecules Vol. 10, p. 877 (1
977) (Macromolecules, 10°877 (1977)), J (2), page 2, lines 13-17 r D, G, Sct
ewart.

D, Y, Waddan...... Japanese Patent Publication No. 1983
-145797),” is corrected as follows.

“British Patent No. 785.229 (1957).

Journal of Polymer Science A-1 Division
Volume 4, page 728 (1966) (Journalof
Polymer 5science＾-1,4,728
(1966)), Polymer, vol. 12, p. 642 (
1971) (Polymer ear 642 (1971)
)) Japanese Patent Application Laid-Open No. 54-145797)

Claims (1)

[Claims] A method for depolymerizing a cyclic polyalkylene ether, which comprises using a heteropolysalt or a salt thereof as a catalyst when depolymerizing the cyclic polyalkylene ether using a catalyst to obtain a constituent monomer.