JPH0627163B2 - 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, using a boron trifluoride-based catalyst, at the time of bulk-polymerizing trioxane or the like to produce an oxymethylene homopolymer or copolymer, at least selected from the group consisting of sodium sulfite, potassium sulfite, calcium sulfite and barium sulfite. The present invention relates to a method of adding a kind of metal sulfite to stop the polymerization reaction.

<Prior Art> It is known, for example, from JP-B-44-5234 to obtain a polyacetal homopolymer or copolymer by bulk polymerization of trioxane alone or trioxane and a cyclic ether and / or a cyclic acetal.

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, the polyacetal homopolymer or copolymer obtained by cationically polymerizing trioxane, etc., gradually depolymerize unless a catalyst remaining in it is deactivated, causing a remarkable decrease in molecular weight, or thermally. It 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, the catalyst is washed. It is described that, by removing these, the polymer is stabilized, and 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 a polymer obtained by bulk polymerization in the presence of at least one polymerization catalyst selected from the group consisting of coordination compounds with organic compounds containing sulfur atoms, sodium sulfite, potassium sulfite, calcium sulfite and sulfite. A method for terminating a bulk polymerization reaction characterized by adding at least one metal sulfite salt selected from the group consisting of barium, preferably at least selected from the group consisting of sodium sulfite, potassium sulfite, calcium sulfite and barium sulfite. A metal sulfite and a phosphine represented by the following general formula (1) The present invention provides a method for stopping the above-mentioned bulk polymerization reaction by adding sphing oxides.

(In the formula, R1, R2, and R3 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 bulk polymerized. Here, the cyclic ether or cyclic acetal means a compound represented by the following general formula (2).

(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 — may be used, and in this case, m = 1 and p is an integer of 1 to 3) Among the cyclic ethers or cyclic acetals represented by the general formula (2), 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 etherite 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 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.

Various devices for bulk polymerization of trioxane alone or trioxane and cyclic ether and / or cyclic acetal are known, but the method for stopping the polymerization reaction of the present invention is not particularly limited by the device, and trioxane may be used. On the other hand, if it is 10% by weight or less, it can be applied to a polymerization reaction carried out in the presence of an organic solvent such as cyclohexane.

In the bulk polymerization, an apparatus having a strong stirring ability and controlling the reaction temperature is particularly preferably used because rapid solidification and heat generation occur during the polymerization.

As the bulk polymerization apparatus of the present invention having such performance, a kneader having a sigma type stirring blade, a cylindrical barrel as a reaction zone, and a screw having coaxial and a large number of interrupted mountains in the barrel, A mixer that operates so that the interruption portion and the teeth protruding on the inner surface of the barrel mesh with each other,
In a long case having a jacket for heating or cooling, a normal screw extruder having a pair of mutually parallel parallel screws, two horizontal stirring shafts having a large number of pattles,
A self-cleaning mixer or the like that rotates when the shaft is simultaneously rotated in the same direction while maintaining a slight clearance between the mating paddle surface and the inner surface of the case.

Also, in bulk polymerization, a strong stirring ability is required because it solidifies rapidly in the initial stage of the polymerization reaction, but once pulverized, a large stirring ability is not required thereafter, so the bulk polymerization step is not performed. It may be divided into stages.

The bulk polymerization reaction temperature is preferably in the temperature range from near the melting point to near the boiling point of trioxane, that is, in the range of 60 to 110 ° C, and particularly preferably in the range of 60 to 95 ° C.

At the initial stage of the polymerization, the temperature in the polymerization reaction device tends to rise particularly due to the reaction heat and the frictional heat caused by solidification, so it is desirable to control the reaction temperature by passing cooling water through the jacket. .

A terminator for deactivating the boron trifluoride-based catalyst used in the present invention to terminate the polymerization reaction, that is, at least one metal sulfite selected from the group consisting of sodium sulfite, potassium sulfite, calcium sulfite and barium sulfite and /
Alternatively, the phosphine oxides are added as they are or as an organic solvent solution or suspension and mixed.

When the terminator is added, it is preferable to control the temperature in the range of 0 to 100 ° C so that depolymerization does not proceed.

Further, in order to allow the reaction between the terminating agent and the polymerization catalyst to proceed sufficiently, it is preferable that the polymer is in a powdery form as fine as possible. Therefore, the polymer may be pulverized by a pulverizer before the addition of the terminating agent. Alternatively, it may be crushed after the addition of the terminating agent.

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 (1) 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.

If the addition amount of the terminator of the present invention is equimolar or more to the boron trifluoride-based catalyst of the polymerization catalyst used, the effect of the present invention is realized, but the addition amount of 2 to 10 times the molar amount is It is efficient.

<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 A 3000 cc kneader having two Σ type stirring blades was placed at 60 ° C.
The mixture is heated to 3000 g of trioxane, 75 g of 1,3-dioxolane, and boron trifluoride / diethyl etherate as a catalyst at 200 pp relative to the weight of trioxane.
m was added as a 10% benzene solution and stirred at about 30 rpm.

The contents solidified within a few minutes and the temperature inside the system rose due to reaction heat and frictional heat. Therefore, compressed air was passed through the Σ-type stirring blade to cool it, and the rotation speed was lowered to bring the maximum temperature to 80 ° C.
Controlled by.

After 60 minutes from the addition of the catalyst, the temperature was lowered to 40 ° C., powder of sodium sulfite (average particle diameter 300 μm) was added in an amount of 5 times the mole of the catalyst (1% based on trioxane), and the mixture was further stirred for 12 minutes. Then, the polymer was taken out.

The obtained polymer was a white powder and had an intrinsic viscosity ηmh = 1.3.
8 was a white powder.

Comparative Example 1 The procedure of Example 1 was repeated except that 2.14 g of triethylamine was used as the catalyst deactivator instead of sodium sulfite. The obtained polymer was a white powder.

The intrinsic viscosity ηmh was 1.21. The changes over time in the thermal decomposition rate K ₂₂₂ of the samples of Example 1 and Comparative Example 1 were measured, and the results are shown in Table 1.

From Table 1, it is clear that the present invention using sodium sulfite has excellent thermal stability of the polymer.

Example 2 To the polymer obtained in the same manner as in Example 1, 0.5% by weight of Irganox 1010 (a hindered phenolic heat-resistant agent manufactured by Ciba Geigy) and 0.1% by weight of calcium hydroxide were added. 20 at 210 ° C / 30 rpm
Kneaded for minutes.

The ηmhK ₂₂₂ and K ₂₄₀ of the obtained polymer are shown in Table 2.

Examples 3 to 5 Polymers were produced in the same manner as in Example 2 except that 0.5 times mol, 5 times mol, and 50 times mol of triphenylphosphine oxide were added to the catalyst in addition to sodium sulfite. did.

Table 2 also shows ηmh, K ₂₂₂ and K ₂₄₀ of the obtained polymer.

Comparative Example 2 A polymer was produced in the same manner as in Examples 2 to 5 except that triethylamine alone was used as a catalyst deactivator in an amount of 5 times the mole of the catalyst.

The ηmh, K ₂₂₂ and K ₂₄₀ of this polymer are shown in Table 2.

Comparative Example 3 A polymer was produced in the same manner as in Example 2 except that triphenylphosphine oxide alone was added as a catalyst deactivator in an amount of 5 times the amount of the catalyst.

Table 2 shows ηmh, K ₂₂₂ and K ₂₄₀ of the obtained polymer.

As is clear from Table 2, the addition of triphenylphosphine oxide alone or triethylamine alone has a low catalyst deactivating effect, resulting in low ηmh and markedly poor thermal stability.

On the other hand, the catalyst deactivating effect of sodium sulfite is large, and the thermal stability of the polymer is good. Furthermore, when used in combination with triphenylphosphine oxide, the catalyst deactivating effect is increased and the thermal stability of the polymer is also increased.

<Effects of the Invention> The method for terminating the polymerization reaction according to the present invention does not require removal of the catalyst, and thus not only can the production process be greatly simplified, but also a polymer having extremely high heat stability can be obtained.

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. A polymer obtained by bulk polymerization in the presence of at least one polymerization catalyst selected from the group consisting of position compounds, at least one selected from the group consisting of sodium sulfite, potassium sulfite, calcium sulfite and barium sulfite. A method for stopping a bulk polymerization reaction, which comprises adding a metal sulfite salt.