JPH06830B2 - 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, it relates to a method of stopping the polymerization reaction by adding a hindered amine compound when producing an oxymethylene homopolymer or copolymer by solution polymerization or suspension polymerization of trioxane or the like using a boron trifluoride-based catalyst. is there.

<Prior Art> It is known, for example, from Japanese Patent Publication No. 36-14640 to obtain an oxymethylene homopolymer or copolymer by solution polymerization or suspension polymerization of trioxane alone or trioxane and cyclic ether and / or cyclic acetal. . The polymer obtained by solution polymerization or suspension polymerization is thermally unstable as it is.Therefore, in the case of homopolymer, the end group is blocked by esterification, and in the case of copolymer, it is unstable. It is stabilized by decomposing and removing the terminal group, but prior to that, it is necessary to deactivate the catalyst and terminate the polymerization reaction.

That is, oxymethylene homopolymers and copolymers obtained by cationically polymerizing trioxane, etc., gradually depolymerize unless a catalyst remaining in them is deactivated, and a remarkable decrease in molecular weight occurs, or thermal It becomes an extremely unstable polymer.

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 deactivated with an ordinary amine compound, depolymerization still occurs when the polymer is dissolved or melted unless the catalyst is removed from the polymer by washing. A decrease in molecular weight is seen.

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

Therefore, the present inventors have arrived at the present invention as a result of earnestly studying the deactivation of the boron trifluoride-based catalyst and the termination of the polymerization reaction in order to solve the above-mentioned problems of the prior art.

<Means for Solving Problems> That is, in the present invention, trioxane or a mixture of trioxane and a cyclic ether and / or a cyclic acetal is treated with boron trifluoride, boron trifluoride hydrate, and boron trifluoride and an oxygen atom. Alternatively, to a polymer solution or a polymer suspension obtained by solution polymerization or suspension polymerization in the presence of at least one polymerization catalyst selected from the group consisting of coordination compounds with organic compounds containing sulfur atoms. The present invention provides a method for terminating a polymerization reaction, which comprises adding a hindered amine compound represented by the following general formula (I).

(In the formula, R1 represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms, and R2 to R5 represent an alkyl group having 1 to 5 carbon atoms, and they may be the same or different from each other. N may be an integer of 1 or more, and R6 may be an n-valent organic residue. The method for terminating the polymerization reaction of the present invention is to use solution polymerization of trioxane alone or a mixture of trioxane and a cyclic ether and / or a cyclic acetal. Alternatively, the cyclic ether or cyclic acetal used in the present invention, which is carried out during suspension polymerization, means a compound represented by the following general formula (II).

(However, in the formula, Y1 to Y4 are a hydrogen atom and a carbon number of 1 to 6
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-dioxepane, 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.

The solvent used in the solution polymerization or suspension polymerization of the present invention may be inert to trioxane, cyclic ethers or cyclic acetals and catalysts, such as aliphatic carbonization such as n-hexane, n-heptane and cyclohexane. Hydrogen, chloroform, halogenated hydrocarbons such as 1,2-dichloroethane, aromatic hydrocarbons such as benzene, toluene, xylene, esters such as dimethyl adipate and dimethyl geltarate can be used, but particularly formed. N-hexane and cyclohexane are preferably used because they are easily separated from the polymer.

The polymerization reaction temperature of the solution polymerization or suspension polymerization of the present invention is performed in the range of 0 to 100 ° C, preferably 20 to 80 ° C.

The polymerization reaction is preferably carried out in a dry inert atmosphere, for example, in a nitrogen gas or carbon dioxide gas atmosphere, usually under normal pressure, but it can also be carried out under high pressure.

As the hindered amine compound used in the present invention,
The compounds of the following structural formulas are mentioned, but a tertiary amine type hindered amine compound is preferably used in view of the color tone of the obtained polymer.

The hindered amine compound may be added as it is or as a solution of an organic solvent.
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,
Examples thereof include halogenated hydrocarbons such as dichloromethane and 1,2-dichloroethane, and ketones such as acetone and methyl ethyl ketone.

The addition amount of the terminating agent of the present invention is preferably such that a hindered amine structure having an equimolar amount or more with the polymerization catalyst used is present. The catalyst deactivating effect can be seen even when the number of moles of the hindered amine structure is less than the number of moles of the catalyst used, but the heat stability of the obtained polymer is slightly lowered, so depending on the degree of heat stability of interest. It is necessary to adjust the addition amount.

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

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

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 with a stream of dry nitrogen air. In this flask 800 g trioxane, 540 g cyclohexane, 20 g 1,3
-Charged with dioxolane. At this time, the water content of the reaction mixture was measured by the Kar1-Fischer method and found to be 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, Sanol LS765 (Ciba-Gei) was added.
gy hindered amine compound, structural formula G-2 described above.
0.14 g) was dissolved in 100 m of benzene and added, and the mixture was stirred for 5 minutes. The contents were suction filtered and the polymer formed was removed and dried under reduced pressure.

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

Examples 2-4 Sanol LS765 0.57g, 2.90g, 2
A polymer was produced in the same manner as in Example 1 except that 9.0 g was used, and ηinh, K ₂₂₂ and K ₂₄₀ were measured.

The results are shown in Table 1 below.

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

Ηinh, 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 Sanol LS765.

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

Proportional Example 2 A polymer was prepared in the same manner as in Example 1 except that 1.05 g (5 times mol of the catalyst) of tri (n-butyl) amine was used instead of Sanol LS765.

Ηinh, 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 separating the polymer by suction filtration and washing twice with 1 liter of water,
It was dried under reduced pressure.

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

It can be seen from Table 1 that the hindered amine compound of the present invention has a greater catalyst deactivating effect than ordinary amine compounds, and that the effect is not affected by the copolymerization component and that the heat stability is stable even if the catalyst is not removed by washing or the like. It is clear that it is superior to.

<Effect of the Invention> In the method for stopping the polymerization reaction according to the present invention, it is not necessary to remove the catalyst by washing, and by using the present stopping method, the process for producing an 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. Hindered amine represented by the following general formula (I) with respect to a polymer solution or a polymer suspension obtained by solution polymerization or suspension polymerization in the presence of at least one polymerization catalyst selected from the group consisting of coordination compounds. A method for terminating a polymerization reaction, which comprises adding a compound. (In the formula, R1 represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms, and R2 to R5 represent an alkyl group having 1 to 5 carbon atoms, and they may be the same or different from each other. N may represent an integer of 1 or more, and R6 represents an n-valent organic residue).