JPH0627164B2 - How to stop the polymerization reaction - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for terminating a polymerization reaction by deactivating a catalyst for a polymerization reaction such as trioxane using a novel polymerization terminator.

More specifically, when a oxymethylene homopolymer or copolymer is produced by dissolution polymerization or suspension polymerization of trioxane using a boron trifluoride-based catalyst, a group consisting of sodium sulfite, potassium sulfite, calcium sulfite and barium sulfite. The present invention relates to a method of stopping the polymerization reaction by adding at least one metal sulfite selected from

<Prior Art> Obtaining a polyacetal homopolymer or copolymer by solution polymerization or suspension polymerization of trioxane alone or trioxane and cyclic ether and / or cyclic acetal is known, for example, from Japanese Patent Publication No. 36-14640. .

The obtained polymer is thermally unstable as it is, so in the case of homopolymer the end groups are blocked by esterification, and in the case of copolymers the unstable end groups are decomposed and removed to stabilize. However, prior to that, it is necessary to stop the reaction by deactivating the catalyst.

That is, an oxymethylene homopolymer or copolymer obtained by cationically polymerizing trioxane or the like is a polymer that gradually depolymerizes unless a catalyst remaining in the polymer is deactivated, resulting in a remarkable decrease in molecular weight or thermal reaction. Becomes extremely unstable.

Regarding the deactivation of the boron trifluoride-based polymerization catalyst, US Pat. No. 2,989,509 proposes to use an aliphatic amine or a heterocyclic amine. After deactivating the catalyst with these amine compounds, washing is performed. It is described that the polymer is stabilized by removing them by doing so, and that the molecular weight does not decrease even if it is stored for a long period as it is.

<Problems to be Solved by the Invention> However, even if the catalyst is not removed from the polymer by washing even if it is deactivated with an ordinary amine compound, depolymerization also occurs when the polymer is dissolved or melted, and the molecular weight is reduced. Is seen to decrease.

Therefore, it was essential to remove the catalyst from the polymer by a sufficient washing operation after deactivating the catalyst with the amine compound.

The present inventors, in order to solve the above-mentioned drawbacks of the prior art, regarding the deactivation of the boron trifluoride-based catalyst and the termination of the polymerization reaction,
As a result of intensive studies, the present invention has been achieved.

<Means for Solving Problems> That is, according to the present invention, trioxane or a mixture of trioxane and a cyclic ether and / or a cyclic acetal is boron trifluoride, boron trifluoride hydrate, and boron trifluoride and an oxygen atom. Or, for a polymer obtained by solution polymerization or suspension polymerization in the presence of at least one polymerization catalyst selected from the group consisting of a coordination compound with an organic compound containing a sulfur atom, sodium sulfite, potassium sulfite, A method of terminating a polymerization reaction, which comprises adding at least one metal sulfite selected from the group consisting of calcium sulfite and barium sulfite, preferably sodium sulfite, potassium sulfite, calcium sulfite and barium sulfite. At least one metal sulfite selected and the following general formula (I) The present invention provides a method for terminating the above polymerization reaction by adding the phosphine oxides represented by

(In the formula, R 1, R 2 and R 3 are hydrocarbon groups having 1 to 18 carbon atoms and may be the same or different.) The method for terminating the polymerization reaction of the present invention is trioxane alone or trioxane. And the cyclic ether and / or cyclic acetal are subjected to solution polymerization or suspension polymerization, and the cyclic ether or cyclic acetal means a compound represented by the following general formula (II).

(However, in the formula, Y1 to Y4 are hydrogen atoms, and have 1 to 6 carbon atoms.
And the halogen-substituted alkyl group having 1 to 6 carbon atoms, which may be the same or different.
X represents a methylene or oxymethylene group, which may be substituted with an alkyl group or a halogen-substituted alkyl group, and m represents an integer of 0 to 3. Alternatively, X is-(CH
_{2) p-O-CH 2} - or _{-O-CH 2 - (CH 2} ) p
—O—CH ₂ —, in which case m = 1 and p is an integer of 1 to 3) In the cyclic ether or cyclic acetal represented by the general formula (II), Particularly preferred compounds include ethylene oxide, propylene oxide, 1,3-dioxolane,
1,3-dioxane, 1,3-dioxeban, 1,3
5-trioxepane, 1,3,6-trioxocane, epichlorohydrin and the like can be mentioned.

The polymerization catalyst of the present invention comprises one or more compounds selected from the group consisting of boron trifluoride, a boron trifluoride hydrate and a coordination compound of an organic compound having an oxygen or sulfur atom and boron trifluoride, a gas. It is used in the form of a liquid, a liquid or a suitable organic solvent.

Examples of the organic compound having an oxygen atom or a sulfur atom which forms a coordination compound with boron trifluoride include alcohol, ether, phenol and sulfide.

Among these catalysts, a coordination compound of boron trifluoride is particularly preferable, and boron trifluoride / diethyl etherate and boron trifluoride / dibutyl etherate are particularly preferably used.

Examples of the solvent for the polymerization catalyst of the present invention include benzene, toluene, aromatic hydrocarbons such as xylene, n-hexane,
Aliphatic hydrocarbons such as n-heptane and cyclohexane, alcohols such as methanol and ethanol, halogenated hydrocarbons such as chloroform, dichloromethane, 1,2-dichloroethane, ketones such as acetone and methyl ethyl ketone are used. .

The amount of the polymerization catalyst added is 5 with respect to 1 mol of trioxane.
It is in the range of x10 ^-6 to 1 x 10 ^-1 mol, particularly preferably in the range of 1 x 10 ^-5 to 1 x 10 ^-2 mol.

As the metal sulfite used in the present invention, at least one selected from the group consisting of sodium sulfite, potassium sulfite, calcium sulfite and barium sulfite is used, but sodium sulfite is particularly preferably used.

The phosphine oxides represented by the general formula (I) used in the present invention include triphenylphosphine oxide, tri-n-butylphosphine oxide and di-phosphine oxide.
Examples thereof include n-butylbenzylphosphine oxide, dicyclohexylphenylphosphine oxide and tritolylphosphine oxide, with triphenylphosphine oxide being preferred.

The polymerization terminator of the present invention may be added as it is, but may be added as a solution or suspension of an organic solvent in order to promote contact with the polymerization catalyst. Examples of the organic solvent at that time include aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as n-hexane, n-heptane and cyclohexane, alcohols such as methanol and ethanol, chloroform, dichloromethane and the like. Examples thereof include halogenated hydrocarbons such as 1,2-dichloroethane, ketones such as acetone and methyl ethyl ketone.

The effect of the present invention can be realized even if the amount of the terminating agent of the present invention added is not more than an equimolar amount with respect to the polymerization catalyst used.
0 times the mole is efficient.

The solvent used in the solution polymerization or suspension polymerization of the oxymethylene homopolymer or copolymer of the present invention may be inert to trioxane, a cyclic ether or a cyclic acetal and a catalyst, such as n-hexane, n-heptane, Aliphatic hydrocarbons such as cyclohexane, halogenated hydrocarbons such as chloroform and 1,2-dichloroethane, aromatic hydrocarbons such as benzene, toluene and xylene, and esters such as dimethyl adipate and dimethyl glutarate. Can be used, but n-hexane and cyclohexane are particularly preferable.

The polymerization reaction of the present invention is carried out at 0 to 100 ° C., preferably 30 to 8
It is carried out in the temperature range of 0 ° C. The polymerization reaction is preferably carried out in a dry inert atmosphere, for example, in a nitrogen or carbon dioxide atmosphere, usually under normal pressure, but it can also be carried out under high pressure.

<Example> Next, the present invention will be described with reference to Examples and Comparative Examples. The logarithmic viscosity ηmh and the thermal decomposition rate K shown in Examples and Comparative Examples are measured as follows.

ηmh 0.5 g of the polymer was dissolved in 100 ml of p-chlorophenol containing 2% of α-pinene, and measured at 60 ° C.

Decomposition rate at Kx X ° C Using a sample of about 10 mg, the decomposition rate after a certain period of time in an air atmosphere was determined by a thermobalance.

W0: sample weight before heating W1: sample weight after heating The thermobalance is a thermal analyzer 1090/109 manufactured by DuPont.
It was measured using 1.

Example 1 2 equipped with a thermometer, a stirring blade, a condenser and a nitrogen introducing tube
The liter round bottom flask was heated under reduced pressure and then cooled by a stream of dry nitrogen. In this flask, 800 g of trioxane, 540 g of cyclohexane, 20 g of 1,3-
Dioxolane was charged. At this time, when the water content of the reaction mixture was measured by the Karl-Fischer method,
It was 90 ppm.

The reaction mixture was then gradually heated in an oil bath with stirring. When the temperature of the contents reaches 60 ℃,
0.16 g (200 ppm relative to trioxane) of boron trifluoride diethyl etherate was added. An exotherm started about 1 minute after the addition, and the internal temperature rose to about 70 ° C. At the same time, the contents became cloudy and became a slurry.
Fifteen minutes after the addition of the catalyst boron trifluoride diethyl etherate, sodium sulfite powder (average particle size 200
Micron) 0.71 g (5 moles relative to catalyst) was added and stirred vigorously for 15 minutes. The polymer produced by suction filtration of the contents was taken out and dried under reduced pressure.

Ηmh, K ₂₂₂ and K ₂₄₀ of the obtained polymer were measured, and the results are shown in Table 1 below.

Examples 2 and 3 A polymer was produced in the same manner as in Example 1 except that 0.07 g and 71.0 g of sodium sulfite were used, respectively.
ηmh, K ₂₂₂ and K ₂₄₀ were measured.

The results are shown in Table 1 below.

Examples 4 and 5 Triphenylphosphine oxide 0.03 each
A polymer was produced in the same manner as in Example 1 except that g and 1.57 g were used in combination.

Ηmh, K ₂₂₂ and K ₂₄₀ of the obtained polymer were measured, and the results are shown in Table 1 below.

Example 6 A polymer was prepared in the same manner as in Example 5 except that 27 g of 1,3-dioxepane was used instead of 1,3-dioxolane.

Ηmh, K ₂₂₂ and K ₂₄₀ of the obtained polymer were measured, and the results are shown in Table 1 below.

Comparative Example 1 A polymer was prepared in the same manner as in Example 1 except that 0.57 g (5 times mol of the catalyst) of triethylamine was used instead of sodium sulfite.

Ηmh, K ₂₂₂ and K ₂₄₀ of the obtained polymer were measured, and the results are shown in Table 1 below.

Comparative Example 2 A polymer was produced in the same manner as in Example 1 except that 1.05 g (5 times mol of the catalyst) tri (n-butyl) amine was used instead of sodium sulfite.

Ηmh, K ₂₂₂ and K ₂₄₀ of the obtained polymer were measured, and the results are shown in Table 1 below.

Comparative Example 3 The polymer of Comparative Example 1 was put into 2 liters of a 2% aqueous ammonia solution and stirred for 30 minutes. After removing the polymer by suction filtration and further washing twice with 1 liter of water,
It was dried under reduced pressure.

Ηmh, K ₂₂₂ and K ₂₄₀ of the obtained polymer were measured, and the results are shown in Table 1 below.

Comparative Example 4 A polymer was produced in the same manner as in Example 1 except that 1.57 g of triphenylphosphine oxide (5 times the mole of the catalyst) was used as the polymerization terminator instead of sodium sulfite.

Ηmh, K ₂₂₂ and K ₂₄₀ of the obtained polymer were measured, and the results are shown in Table 1 below.

From Table 1, the metal sulfite compound of the present invention has a greater catalyst deactivating effect than ordinary amine compounds, and when phosphine oxides are used in combination, the catalyst deactivating effect increases, and the effect is influenced by the copolymerization component. It is clear that it is not exposed to heat and has excellent heat resistance stability even if the catalyst is not removed by washing.

<Effects of the Invention> In the method for terminating the polymerization reaction of the present invention, it is not necessary to remove the catalyst by washing, and by using this terminating method, the production process of the oxymethylene polymer can be simplified.

Claims (1)

[Claims] 1. Trioxane or a mixture of trioxane and a cyclic ether and / or a cyclic acetal is combined with boron trifluoride, boron trifluoride hydrate and boron trifluoride with an organic compound containing an oxygen atom or a sulfur atom. Selected from the group consisting of sodium sulfite, potassium sulfite, calcium sulfite and barium sulfite, with respect to the polymer obtained by solution polymerization or suspension polymerization in the presence of at least one polymerization catalyst selected from the group consisting of position compounds. A method for terminating a polymerization reaction, which comprises adding at least one kind of metal sulfite.