JPH08208784A - Method for stopping polymerization reaction - Google Patents

Abstract

PURPOSE: To stop the polymerization reaction while dispensing with the removal of a catalyst by adding a specified hindered amine compound to a polymer obtained through bulk polymerization of trioxane, etc., in the presence of a boron trifluoride base catalyst. CONSTITUTION: A polymerization reaction is stopped by adding a hindered amine compound of the formula (wherein R<1> to R<4> are each 1-5C alkyl; n is an integer of 1 or greater; and R<5> is an n-valent organic residue) to a polymer obtained through bulk polymerization of trioxane or a mixture of trioxane with a cyclic ether and/or a cyclic acetal in the presence of at least one polymerization catalyst selected from the group consisting of BF3 , BF3 hydrates and coordination compounds of BF3 with O- or S-containing organic compounds. The polymer obtained by adding the hindered amine compound to stop the polymerization reaction dispenses with the removal of the catalyst. Accordingly, the production process can be greatly shortened, while a polymer with very high thermal stability can be obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to deactivating a catalyst for a polymerization reaction such as trioxane using a novel polymerization terminator,
It relates to a method of stopping a polymerization reaction.

More specifically, it relates to a method of adding a hindered amine compound to terminate the polymerization reaction when bulk-polymerizing trioxane or the like using a boron trifluoride type catalyst to produce an oxymethylene homopolymer or copolymer. .

[0003]

2. Description of the Related Art It is known, for example, from JP-B-44-5234 to obtain polyacetal homopolymers or copolymers by bulk polymerization of trioxane alone or trioxane and cyclic ethers and / or cyclic acetals.

The polymer obtained by bulk polymerization is thermally unstable as it is. Therefore, in the case of a homopolymer, the terminal group is blocked by esterification or the like, and in the case of a copolymer, an unstable terminal is obtained. Although the group is stabilized by decomposing and removing it, it is necessary to deactivate the catalyst and stop the polymerization reaction prior to the stabilization.

That is, a polyacetal homopolymer or copolymer obtained by cationically polymerizing trioxane or the like gradually undergoes depolymerization unless a catalyst remaining therein is deactivated, and a remarkable decrease in molecular weight occurs. It becomes a polymer that is extremely thermally unstable.

Regarding 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, It is described that, if these are removed by washing, the polymer is stabilized, and the molecular weight does not decrease even if it is stored for a long period as it is.

[0007]

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

Therefore, it was indispensable 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 extensive studies on 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. .

[0010]

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

[0011]

Embedded image (However, in the formula, R ^{1 to} R ⁴ represent an alkyl group having 1 to 5 carbon atoms, and may be the same or different from each other. N is an integer of 1 or more, and R ⁵ is n-valent. Indicates an organic residue.)

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The method for terminating a polymerization reaction of the present invention comprises trioxane alone or trioxane and a cyclic ether and / or
Alternatively, it is carried out in bulk polymerization of a mixture of cyclic acetals, and the cyclic ether or cyclic acetal used in the present invention means a compound represented by the following general formula (II).

[0013]

Embedded image (However, in the formula, Y ^{1 to} Y ⁴ are a hydrogen atom and a carbon number 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
It may be —O—CH ₂ —, in which case m = 1 and p is an integer from 1 to 3. ) Among the cyclic ethers or cyclic acetals represented by the above general formula (II), as particularly preferable compounds, 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.

The solvent for the polymerization catalyst of the present invention includes aromatic hydrocarbons such as benzene, toluene and xylene, and n-.
Aliphatic hydrocarbons such as hexane, 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. To be done.

The amount of the polymerization catalyst added is in the range of 5 × 10 ^-6 to 1 × 10 ^-1 mol per 1 mol of trioxane,
Particularly preferably, it is in the range of 1 × 10 ⁻⁵ to 1 × 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
It is not particularly limited by the device, and if it is 10% by weight or less based on trioxane, it can be applied to a polymerization reaction carried out in the presence of an organic solvent such as cyclohexane.

In bulk polymerization, an apparatus having a strong stirring ability and capable of 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 a large number of interrupted ridges coaxially in the barrel are used. A mixer that operates so that the interrupted portion and teeth protruding from the inner surface of the barrel mesh with each other, a conventional screw extruder having a pair of mutually parallel parallel screws in a long case having a heating or cooling jacket, Self-cleaning mixer with multiple paddles on a horizontal stirring shaft of a book, and when the shafts are simultaneously rotated in the same direction, they rotate with a slight clearance between the paddle surface and the inner surface of the case. Etc. can be mentioned.

In the bulk polymerization, solidification rapidly occurs at the beginning of the polymerization reaction, so that strong stirring ability is required.
Once pulverized, the bulk polymerization process may be divided into two stages since no large stirring ability is required thereafter.

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 apparatus tends to rise particularly due to the reaction heat and the frictional heat caused by solidification. Therefore, the reaction temperature is controlled by passing cooling water through the jacket. Is desirable.

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, the temperature is preferably controlled within 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 the form of powder as fine as possible. Alternatively, it may be crushed after adding a terminating agent. Examples of the hindered amine compound used in the present invention include compounds having the following structures.

[0024]

[Chemical 4]

Embedded image

[Chemical 6]

[Chemical 7] 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-
Examples include aliphatic hydrocarbons such as hexane, 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. To be

The terminating agent of the present invention is preferably added in such a manner that a hindered amine structure is present in an equimolar amount or more to the polymerization catalyst used. 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.

[0026]

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

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

Kx = {(W ₀ −W ₁ ) / W ₀ } × 100 (%) W ₀ = Sample weight before heating 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 inside of the Σ-type stirring blade, and the rotation speed was further 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., and K, T and U were added as catalyst deactivators to 10.
0 g was added as a 20% benzene solution, the mixture was further stirred for 12 minutes, and then the polymer was taken out.

The color tone of the obtained polymer was visually evaluated, ηinh, and the decomposition rate after holding at 222 ° C. for 30 minutes were measured.

The results are shown in Table 1.

[0034]

[Table 1] Comparative Example 1 The procedure of Example 1 was repeated, except that 2.14 g of triethylamine was used instead of the compounds K, T and U as the catalyst deactivator. The obtained polymer was a white powder.

Also, the logarithmic viscosity ηinh = 1.21,
K ₂₂₂ , 30 minutes was 71%. Example 1, Comparative Example 1
From the above, it is clear that the polymer using the hindered amine compound has excellent thermal stability.

[0036]

INDUSTRIAL APPLICABILITY The polymer of which the polymerization reaction has been stopped according to the present invention does not require removal of the catalyst, so that not only the production process can be shortened significantly but also a polymer having extremely high heat stability can be obtained.

Claims (1)

[Claims] 1. A mixture of trioxane or trioxane and a cyclic ether and / or a cyclic acetal is prepared by combining 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. Embedded image (However, in the formula, R ^{1 to} R ⁴ represent an alkyl group having 1 to 5 carbon atoms, and may be the same or different from each other. N is an integer of 1 or more, and R ⁵ is n-valent. Indicates an organic residue.)