JPH06829B2 - 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 bulk-polymerizing trioxane or the like using a boron trifluoride-based catalyst to produce an oxymethylene homopolymer or copolymer.

<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 polymer obtained by bulk polymerization is thermally unstable as it is.Therefore, in the case of a homopolymer, the end group is blocked by esterification, and in the case of a copolymer, the unstable end group is decomposed. Although it has been removed and stabilized, it is necessary to deactivate the catalyst and terminate the polymerization reaction prior to that.

That is, polyacetal homopolymers and copolymers obtained by cationically polymerizing trioxane and the like, unless deactivating the catalyst remaining therein, gradually depolymerize, a significant decrease in molecular weight occurs, or thermally. 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, 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 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 has been essential to remove the catalyst from the polymer by a sufficient washing operation after deactivating the catalyst from 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, for a polymer obtained by bulk 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, a hindered amine represented by the following general formula (I) The present invention provides a method for stopping a polymerization reaction, which is characterized by 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).

The polymerization reaction termination method of the present invention is performed when bulk polymerization of trioxane alone or a mixture of trioxane and a cyclic ether and / or a cyclic acetal is carried out. The cyclic ether or cyclic acetal used in the present invention is represented by the following general formula: It means a compound represented by (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.

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 paddles,
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 can be used.

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.

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. .

The terminating agent for deactivating the boron trifluoride-based catalyst used in the present invention to terminate the polymerization reaction is added as it is or as an organic solvent solution 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. After adding the terminating agent, it may be ground.

As the hindered amine compound used in the present invention,
Examples include compounds having the following structural formulas.

Among these hindered amine compounds, a tertiary amine type hindered amine compound is particularly preferably used because the obtained polymer has an excellent color tone.

The terminating agent of the present invention may be added as it is,
It may be added as a solution of an organic solvent to promote contact with the polymerization catalyst. As the organic solvent at that time, aromatic hydrocarbons such as benzene, toluene and xylene, n
-Hexane, n-heptane, aliphatic hydrocarbons such as cyclohexane, alcohols such as methanol and ethanol, halogenated hydrocarbons such as chloroform, dichloromethane, 1,2-dichloroethane, and ketones such as acetone and methyl ethyl ketone. Can be mentioned.

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. Even if the number of moles of the hindered amine structure is less than the number of moles of the catalyst used, the catalyst deactivating effect can be seen, but the heat stability of the obtained polymer is slightly lowered, so depending on the desired degree of heat stability. It is necessary to adjust the amount of addition.

<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 polymer was dissolved in 100 m of p-chlorophenol containing 2% α-pinene and 60
It was measured at ° 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.

60 minutes after the addition of the catalyst, the temperature was lowered to 40 ° C. and the hindered amine compound represented by the structural formula (G-2) (Cib
a-Geigy Sanol LS 765) 11.
4 g was added as a 20% benzene solution, the mixture was stirred for 12 minutes, and then the polymer was taken out. The obtained polymer was a white powder and had an inherent viscosity ηinh = 1.44.

Comparative example 1 It carried out like Example 1 except having used 2.14g of triethylamine instead of compound (G-2) as a catalyst deactivator. The obtained polymer was a white powder.

The logarithmic viscosity ηinh = 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 polymer using the hindered amine compound of the present invention is superior in thermal stability.

Example 2 Instead of the hindered amine compound represented by the compound (G-2) as a catalyst deactivator, (K-2), (K-1),
(T-2), (T-1) and (U-1) are each 1
Example 1 was repeated except that 0.0 g was added. Visual color tone of the obtained polymer, ηinh and 222
The decomposition rate was measured after holding at 30 ° C. for 30 minutes.

The results are shown in Table 2.

From Table 2, it is clear that the polymer using the hindered amine compound has excellent thermal stability.

Examples 3 to 6 0.57 g, 1.14 g, 11.4 g of a hindered amine compound represented by the structural formula (G-2) as a catalyst deactivator.
Polymerization was carried out in the same manner as in Example 1 except that g and 114 g were added as a benzene solution.
Weight% Irganox 1010 (a hindered phenolic heat-resistant agent manufactured by Ciba-Geigy) and 0.1 weight% calcium hydroxide were added, and 2 at 210 ° C./30 rpm was added.
Melt kneading for 0 minutes.

Comparative Example 2 A polymer was produced in the same manner as in Examples 3 to 6 except that 2.14 g of triethylamine was used as the catalyst deactivator.

Table 3 shows ηinh, thermal decomposition rates K ₂₂₂ and K ₂₄₀ of Examples 3 to 6 and Comparative Example 2.

As is clear from Table 3, when the catalyst is deactivated by the hindered amine compound, it has very high heat stability even if the catalyst is not removed by washing or the like. On the other hand, when the catalyst is deactivated with triethylamine,
The produced polymer also has a low ηinh, and its thermal stability is extremely poor.

Example 7 A polymer was prepared in the same manner as in Example 1, except that 42 g of ethylene oxide was used instead of 1,3-dioxolane. Ηinh of this polymer is 1.36 and K
₂₂₂ (30 minutes) showed good heat resistance at 10%.

<Effects of the Invention> The polymer of which the polymerization reaction has been stopped according to the present invention does not need to remove the catalyst, so that not only the production process can be significantly shortened 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. Polymerization characterized by adding a hindered amine compound represented by the following general formula (I) to a polymer obtained by bulk polymerization in the presence of at least one polymerization catalyst selected from the group consisting of position compounds How to stop the reaction. (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).