JPS6112713A - Production of oxymethylene copolymer - Google Patents

Abstract

PURPOSE:The copolymerization of trioxane with a cyclic ether is effected in the presence of allyl glycidyl ether to enable the production of the titled copolymer which is suitable for use in extrusion molding with a low melt index without reduction in polymerization yield. CONSTITUTION:The copolymerization of trioxane and a cyclic ether (preferably ethylene oxide) is conducted in the presence of allyl glycidyl ether, preferably using boron fluoride ethyl etherate as a catalyst, preferably at 45-115 deg.C for 0.25-120min to give the objective copolymer. The amounts of allyl glycidyl ether and the cyclic ether are preferably 0.2-3.0wt% and 0.2-5.0wt%, respectively, based on trioxane.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a process for the production of oxymethylene copolymers having particularly reduced MI values (melt index).

In general, oxymethylene copolymers obtained by copolymerizing trioxane and cyclic ethers have a relatively high MI value, and are therefore mainly used in the field of injection molding.

On the other hand, oxymethylene copolymers with such a high MI value cannot be used in fields that require relatively special shaping properties such as extrusion molding and blow molding, and it has been desired to lower the MI value. Ta.

Conventionally, as a method for lowering the MI value of oxymethylene copolymers, the oxymethylene copolymers can be split or split by adding a specific bifunctional compound during the copolymerization of trioxane and cyclic ether. The method of making it reticulate is
Some suggestions have been made.

That is, for example, a method using diglycidyl ethers as a difunctional compound (Japanese Patent Publication No. 42-3955 and Japanese Patent Publication No. 44-6277), a method using bis-alkyltriol triformal (Japanese Patent Publication No. 44-62)
77), a method using diglycerine diformal (Japanese Patent Publication No. 5124559), and the like.

Problems to be Solved by the Invention However, these bifunctional compounds are special compounds that are difficult to obtain, and since they often reduce the polymerization yield, it is difficult to add them in large amounts. In addition, the Ml value of the obtained oxymethylene copolymer does not necessarily show a constant value, making stable production difficult. Therefore, these known methods were not satisfactory from an industrial point of view.

In view of these drawbacks of conventional methods, the present inventors have conducted extensive research and found that by using allyl diglycidyl ether as a bifunctional compound, the Ml value can be significantly increased without substantially reducing the polymerization yield. It has been discovered that an improved oxymethylene copolymer can be obtained, and the present invention has been achieved.

A method for solving problem 1, that is, the present invention is a method for producing an oxymethylene copolymer, which comprises copolymerizing trioxane and a cyclic ether in the presence of allyl glycidyl ether.

In the present invention, the appropriate amount of allyl glycidyl ether added is 0.05 to 5.0% by weight, preferably 0.2 to 3.0% by weight based on trioxane.

If the amount added is less than this range, the effect will be small, and if the amount added exceeds this range, no improvement in the effect can be expected.
There is a negative impact on yield.

In the present invention, the cyclic ether is a compound represented by the following general formula.

7 [In the formula, R+, Rz, R4 and R4 are the same or different, and a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogen group having 1 to 3 carbon atoms substituted with 1 to 3 halogen atoms; 5 alkyl groups, R3 is a methylene group, a methylene group substituted with an alkyl group, a methylene group substituted with a halogenated alkyl group, an oxymethylene group, an oxymethylene group substituted with an alkyl group, or a halogenated Represents an oxymethylene group substituted with an alkyl group (in this case, n
is O or an integer of 1 to 3, and the alkyl group of the substituent is
The alkyl group having 1 to 5 carbon atoms or the halogenated alkyl group as a substituent is an alkyl group having 1 to 5 carbon atoms substituted with 1 to 3 halogen atoms), or RS is (C
H)lI 0CHi- or (OCHz CH) IIOCHz- (wherein m is 1
is an integer from ~3).

(In this case, n is 1.) Ethylene oxide, glycol formal and diglycol formal are particularly suitable as the cyclic ether represented by the above formula. Also suitable are, for example, propylene oxide, epichlorohydrin or cyclic formals of long-chain α,ω-diols, such as butanediol formals or hexanediol formals.

The amount of cyclic ether used is 0 for trioxane.
．． 2 to 30% by weight or 0.2 to 5.0% by weight is suitable.

The catalyst used in the copolymerization reaction of the present invention is selected from cationic active polymerization catalysts, particularly boron fluoride, boron fluoride permanents, and coordination complex compounds of boron fluoride and organic substances having sulfur atoms. One type or a mixture of two or more types is suitable;
In particular, boron fluoride diethyl etherate and boron fluoride dibutyl etherate are preferred coordination complex compounds.

In the present invention, the above-mentioned catalyst is used in gaseous, liquid, or solution form in a suitable organic solvent.

, the amount of catalyst used is usually from 30 to 1000 p, expressed as the weight of boron fluoride, relative to the weight of the monomers used.
P is also preferably 100 to 200 ppm.

The polymerization reaction is usually carried out at a temperature of 45 to 115°C, and the polymerization time is usually 0.25 to 120 minutes.

Although an inert solvent such as cyclohexane or benzene may be used as a solvent during polymerization, bulk polymerization that uses almost no solvent is advantageous from an industrial standpoint.

The obtained oxymethylene copolymer can be stabilized using known stabilization methods, such as thermal decomposition as described in Japanese Patent Publication No. 39-8071, etc., or processing as described in Japanese Patent Publication No. 41-29, etc. The unstable portion can be removed by subjecting it to solvent decomposition, or it can be stabilized by the so-called polymer terminal blocking method using an acid anhydride, which is described in Japanese Patent Publication No. 33-6099. desirable.

Furthermore, the oxymethylene copolymer obtained in the present invention includes:
If desired, stabilizers, ultraviolet absorbers, facial dyes, fillers,
It is also possible to blend reinforcing fibers and other additives.

Effects and Results Although the effect of allyl glycidyl ether in the present invention is not necessarily clear, it has little effect on the yield of the polymerization reaction, and the MI value of the obtained copolymer is extremely high. or,
Allyl glycidyl ether is readily available.

Therefore, the industrial advantage of the method of the present invention is extremely high.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in more detail with reference to Examples and Comparative Examples.

In addition, in the examples and comparative examples, the MI value is
These are the measured values at 60 g and a temperature of 190°C.

Example 1 Trioxane was charged into a kneader having two Σ-shaped stirring blades and heated to 60° C. to melt it. To this was added 2.5% by weight of ethylene oxide based on trioxane and 0.67% by weight allyl glycidyl ether based on trioxane, and 0.01 mol% fluorinated diethyl etherate based on trioxane. , Polymerization was carried out for 30 minutes with stirring. After the reaction time was over, triphenylphosphine was added in an amount twice the molar amount of the catalyst to terminate the polymerization, and a crude oxymethylene copolymer was obtained in a yield of 97%.

To this crude oxymethylene copolymer, 0.2% by weight of melamine, 0.1% by weight of magnesium hydroxide, and 0.5% by weight of Irganox 1010 (trade name, sterically hindered phenol manufactured by Ciba Geigy) were added, and Laboplast was added. At the mill 2
The mixture was heated and kneaded at 20° C. for 30 minutes to obtain a stable oxymethylene copolymer.

The M r value of this 4th-dimethylene copolymer is 9
g/10 minutes.

Comparative Example 1 Example 1 except that allyl glycidyl ether was not added.
When the procedure was carried out in exactly the same manner as above, a crude oxymethylene copolymer was obtained in a yield of 99%.

Furthermore, when it was stabilized in exactly the same manner as in Example 1, the MI value of the obtained oxymethylene copolymer was 8.5 g/10
It was a minute.

Example 2 Trioxane was charged into a kneader having two Σ-shaped stirring blades, and heated to 60°C to melt it. To this was added 2.4% by weight of ethylene oxide based on trioxane and 0.3% by weight allyl glycidyl ether based on trioxane, and 0.01 mol% fluorinated diethyl etherate based on trioxane. The polymerization was carried out for 45 minutes under stirring.

After the reaction time was over, triphenylphosphine was added in an amount twice the molar amount of the catalyst to terminate the polymerization, and a crude oxymethylene copolymer was obtained in a yield of 99%.

This crude oxymethylene copolymer was stabilized in exactly the same manner as in Example 1 to obtain a stable oxymethylene copolymer.

The MI value of this oxymethylene copolymer is 3.3g/10
It was a minute.

Example 3 The amount of ethylene oxide added was 2.
A crude oxymethylene copolymer was obtained in a yield of 94% in exactly the same manner as in Example 2 except that the amount of allyl glycidyl ether added was 1.27% by weight based on trioxane. .

Furthermore, when it was stabilized in exactly the same manner as in Example 1, the MI value of the obtained oxymethylene copolymer was 2.3 g/10
It was a minute.

Patent applicant: Mitsubishi Gas Chemical Co., Ltd. Representative Kazuyoshi Nagano

Claims (1)

[Claims] A method for producing an oxymethylene copolymer, which comprises copolymerizing trioxane and a cyclic ether in the presence of allyl glycidyl ether.