JP2015025073A - Method for producing polyacetal copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyacetal copolymer that can produce a high-quality polyacetal copolymer in a high yield with a less generation amount of scale and can maintain polymerization yield for a long period of time.SOLUTION: The method for producing a polyacetal copolymer comprises conducting the polymerization of a trioxane with a cyclic ether and/or a cyclic formal and has a step of mixing a cyclic ether and/or a cyclic formal, a polymerization catalyst and at least one kind of alcohols represented by formula (1) as given below to produce a pre-mixed liquid and a step of supplying the pre-mixed liquid and the trioxane to a polymerization reactor to conduct a polymerization reaction. Formula (1): R-(CH-O)-H (in formula (1), R represents any one selected from the group consisting of hydrogen, a branched or linear alkyl group, a branched or linear alkoxy group and a hydroxyl group; and n represents an integer of 1-20.)

Description

  The present invention relates to a method for producing a polyacetal copolymer.

Conventionally, a polyacetal copolymer is known to be a resin material having excellent rigidity, strength, toughness, slidability, creep properties, etc., mainly in automobile parts, electrical / electronic devices and various mechanical parts. Have been used extensively.
In addition, the development of molding technology using a polyacetal copolymer is remarkable, and there is a high need for a high molecular type polyacetal, and a production method for a high molecular type polyacetal copolymer is desired.

  In addition, parts using a polyacetal copolymer are often important mechanical parts, and quality stabilization is essential. And in order to stabilize quality, it is indispensable to produce a polyacetal copolymer stably for a long period of time.

In the polymerization of the polyacetal copolymer, trioxane is generally used as a raw material, and the polymerization is usually carried out in the presence of a molecular weight regulator to control the molecular weight.
In order to obtain a high molecular weight type polyacetal copolymer, a method in which the molecular weight modifier is decreased, and on the contrary, in order to obtain a low molecular weight type polyacetal copolymer, a method in which the molecular weight modifier is increased is employed.

  On the other hand, as described above, long-term stable operation is important for polyacetal copolymer polymerization in order to stabilize the quality of parts using polyacetal. As a cause of hindering the long-term stable operation, first, it is impossible to supply a stable raw material due to the generation of scale in the polymerization apparatus supply unit, and the polymerization yield is reduced. On the other hand, it is also desired to improve the working environment by reducing squeals and abnormal noises in the polymerization process caused by scale generation.

As a technique for reducing the generation of scale as described above, for example, a method for reducing a polymerization catalyst used in producing a polyacetal copolymer can be mentioned.
As a technique capable of reducing the polymerization catalyst when producing the polyacetal copolymer, for example, a cyclic ether and / or a cyclic formal, a low molecular weight acetal compound, and a polymerization catalyst are mixed in advance, and then , A technology for adding and supplying to trioxane for polymerization (for example, see Patent Document 1), a technology for mixing cyclic ether and / or cyclic formal, a polymerization catalyst, and an organic solvent in advance and bringing them into contact with trioxane for polymerization. (See, for example, Patent Document 2). These are all techniques for achieving a high polymerization yield, that is, techniques capable of reducing the polymerization catalyst.
Further, in Patent Document 1, in order to improve the productivity of polymerization, in the step of copolymerizing trioxane and a cyclic ether, a cyclic ether, a cationic polymerization catalyst, and a low molecular weight acetal are mixed in advance, and this is mixed with trioxane. A polymerization method to be added to is also proposed.

Japanese Patent No. 3850546 Japanese Examined Patent Publication No. 6-62730

However, even with the above-described conventionally proposed technology, the generation of scale in the polymerization apparatus supply unit has not been sufficiently reduced.
Further, in order to improve the productivity of polymerization, in the step of copolymerizing trioxane and cyclic ether, a polymerization method in which cyclic ether, a cationic polymerization catalyst and a low molecular weight acetal are mixed in advance and trioxane is added thereto. When implemented, as described in the Examples of Patent Document 3, the polyacetal obtained is only a low molecular weight polyacetal copolymer, and for example, the melt index measured at 190 ° C. is 50 g / 10 min or less. There is no mention of manufacturing things.

  Therefore, in the present invention, generation of scale can be reduced, and a high-quality polyacetal copolymer can be stably produced continuously for a long period of time with a high polymerization yield. It is an object of the present invention to provide a method for producing a polyacetal copolymer, which can be maintained.

In order to solve the above-mentioned problems, the present inventors have intensively studied. As a result, in the polymerization step of the polyacetal copolymer, a pre-mixed cyclic ether and / or cyclic formal, the polymerization catalyst, and a predetermined alcohol are mixed. By obtaining a mixed liquid, supplying the pre-mixed liquid and trioxane to the polymerization reactor and conducting the polymerization reaction, it was found that the above-described problems of the prior art can be solved, and the present invention has been completed. .
That is, the present invention is as follows.

[1]
A method for producing a polyacetal copolymer for polymerizing trioxane with a cyclic ether and / or a cyclic formal,
The cyclic ether and / or cyclic formal;
A polymerization catalyst;
At least one alcohol represented by the following general formula (1);
To obtain a pre-mixed solution,
Supplying the premixed solution and the trioxane to a polymerization reactor, and performing a polymerization reaction;
The manufacturing method of the polyacetal copolymer which has these.
R— (CH ₂ —O) _n —H (1)
(In General Formula (1), R represents any one selected from the group consisting of hydrogen, a branched or linear alkyl group, a branched or linear alkoxy group, and a hydroxyl group. Represents an integer of 1 to 20.)
[2]
A step of previously mixing the alcohol represented by the general formula (1) with the cyclic ether and / or the cyclic formal, and then mixing the polymerization catalyst to obtain the premixed solution;
Supplying the premixed solution and the trioxane to a polymerization reactor, and performing a polymerization reaction;
The method for producing a polyacetal copolymer according to the above [1].
[3]
A step of previously mixing the alcohol represented by the general formula (1) with a polymerization catalyst, and then mixing the cyclic ether and / or cyclic formal to obtain the pre-mixed solution;
Supplying the premixed solution and the trioxane to a polymerization reactor, and performing a polymerization reaction;
The method for producing a polyacetal copolymer according to the above [1].
[4]
In the step of obtaining the pre-mixed solution, an organic solvent is further used,
The method for producing a polyacetal copolymer according to any one of [1] to [3], wherein the polymerization catalyst is mixed under a temperature condition of 25 ° C. or higher and lower than the boiling point of the organic solvent.
[5]
[1] to [4], wherein the polymerization catalyst is at least one selected from the group consisting of boron trifluoride, boron trifluoride diethyl etherate, and boron trifluoride-di-n-butyl etherate. ] The manufacturing method of the polyacetal copolymer as described in any one of.
[6]
The method for producing a polyacetal copolymer according to [4] or [5], wherein the organic solvent is at least one selected from the group consisting of n-hexane, n-heptane, and cyclohexane.
[7]
The method for producing a polyacetal copolymer according to any one of [1] to [6], wherein a part of at least one alcohol represented by the general formula (1) is mixed with the trioxane.
[8]
At least one alcohol represented by the general formula (1) is methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-1 The method for producing a polyacetal copolymer according to any one of [1] to [7], which is any one selected from the group consisting of -propanol and 2-methyl-2-propanol.
[9]
At least one alcohol represented by the general formula (1) is:
The method for producing a polyacetal copolymer according to any one of [1] to [8], which is used in a range of 0.01 mol to 100 mol with respect to 1 mol of the polymerization catalyst.

  According to the method for producing a polyacetal copolymer of the present invention, generation of scale can be reduced, a high-quality polyacetal copolymer can be stably produced continuously for a long period of time with a high polymerization yield, and less polymerization is performed. Even with a catalyst, the polymerization yield can be maintained over a long period of time.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

[Method for producing polyacetal copolymer]
The production method of the polyacetal copolymer of this embodiment is:
With trioxane,
Cyclic ether and / or cyclic formal;
A method for producing a polyacetal copolymer for polymerization of
Mixing the cyclic ether and / or cyclic formal, a polymerization catalyst, and at least one alcohol represented by the following general formula (1) to obtain a premixed solution;
Supplying the premixed solution and the trioxane to a polymerization reactor, and performing a polymerization reaction;
Is a process for producing a polyacetal copolymer having
R— (CH ₂ —O) _n —H (1)
(In General Formula (1), R represents any one selected from the group consisting of hydrogen, a branched or linear alkyl group, a branched or linear alkoxy group, and a hydroxyl group. Represents an integer of 1 to 20.)

(Materials used in the step of obtaining the pre-mixed solution)
In the method for producing a polyacetal copolymer of the present embodiment, first, the cyclic ether and / or cyclic formal, the polymerization catalyst, and at least one alcohol represented by the general formula (1) are mixed in advance. Thus, a pre-mixed liquid is obtained.
Materials used in the step of obtaining the pre-mixed solution will be described below.

<Cyclic ether and / or cyclic formal>
Cyclic ether and / or cyclic formal is a component copolymerizable with trioxane described later.
Examples of the cyclic ether or the cyclic formal include, but are not limited to, ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, epibromohydrin, styrene oxide, oxatan, and 1,3-dioxolane. , Ethylene glycol formal, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, and the like. From the viewpoint of easy availability, 1,3-dioxolane and 1,4-butanediol formal are preferred.
These may be used alone or in combination of two or more.

The addition amount of the cyclic ether and / or cyclic formal, from the viewpoint of mechanical strength, is preferably in the range of ^{1 × 10 -2 ~20 × 10 -2} mol relative to trioxane 1mol described below, and more preferably 1 × 10 ^{- 2} to 15 × 10 ⁻² mol, more preferably 1 × 10 ⁻² to 10 × 10 ⁻² mol, and even more preferably 1 × 10 ^{−2 to} 5 × 10 ⁻² mol.

<Polymerization catalyst>
Examples of the polymerization catalyst include boric acid represented by Lewis acid, tin, titanium, phosphorus, arsenic, and antimonide. In particular, from the viewpoint of easy availability, boron trifluoride, boron trifluoride hydrate, and a coordination complex compound of an organic compound containing an oxygen atom or a sulfur atom and boron trifluoride are preferable. Specifically, boron trifluoride, boron trifluoride diethyl etherate, and boron trifluoride-di-n-butyl etherate are preferable examples.
These may be used alone or in combination of two or more.

The addition amount of the polymerization catalyst is preferably in the range of 0.1 × 10 ^{−5 to} 0.1 × 10 ⁻³ mol, more preferably 0.3 × 10 ^{−5 to} 0.5 × with respect to 1 mol of trioxane described later. It is in the range of 10 ⁻⁴ mol, more preferably in the range of 0.5 × 10 ^{−5 to} 0.4 × 10 ⁻⁴ mol.
By setting the addition amount of the polymerization catalyst within the above range, it is possible to stably carry out the polymerization reaction for a long time while reducing the amount of scale generated in the supply section of the polymerization reactor.

<At least one alcohol represented by the general formula (1)>
In the method for producing the polyacetal copolymer of the present embodiment, at least one alcohol represented by the following general formula (1) is used as a material for the pre-mixed solution.
R— (CH ₂ —O) _n —H (1)
(In the general formula (1), R represents any one selected from the group consisting of hydrogen, a branched or linear alkyl group, a branched or linear alkoxy group, and a hydroxyl group. Represents an integer of 20 or more.)
Examples of the alcohol represented by the general formula (1) include, but are not limited to, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl- 1-propanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-hexanol, 2-hexanol, 3-hexanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, 4-methyl-1-pentanol, 2-methyl-2-pentanol, 3-methyl-2-pentanol, 4-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-3 -Pentanol, 2,2-dimethyl-1-butanol, 2,3-dimethyl-1-butanol, 3,3-dimethyl-1-butanol, , 3-dimethyl-2-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, ethylene glycol, propylene glycol, and the like. In particular, from the viewpoint of handleability, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-1-propanol, 2-methyl-2- Propanol is preferred. These may be used alone or in combination of two or more.

The at least one alcohol represented by the general formula (1) is a method in which the total amount is mixed with cyclic ether and / or cyclic formal and supplied to the polymerization reactor. The method may be selected from any one of a method of supplying, a method of partially mixing with trioxane described later, supplying the mixture to the polymerization reactor, and mixing the entire remaining amount into the premixed solution and supplying the mixture to the polymerization reactor.
In particular, from the viewpoint of uniform dispersion, it is preferable to select a method of mixing half or more of at least one alcohol represented by the general formula (1) into the pre-mixed solution.

The amount of the at least one alcohol represented by the general formula (1) is preferably in the range of 0.01 mol or more and 100 mol or less with respect to 1 mol of the polymerization catalyst described above.
By setting it as 0.01 mol or more with respect to 1 mol of polymerization catalysts, generation | occurrence | production of the colored scale can fully be suppressed, and it can be set as the usage-amount required practically by setting it as 100 mol or less. .
From the viewpoint of handleability, it is preferably in the range of 0.1 mol to 50 mol, more preferably in the range of 0.1 mol to 10 mol, with respect to 1 mol of the polymerization catalyst.

<Organic solvent>
In the step of obtaining the pre-mixed solution, an organic solvent may be used in combination.
The organic solvent is not particularly limited as long as it does not participate in the polymerization reaction or exert an adverse effect. For example, benzene (boiling point 80 ° C.), toluene (boiling point 110.63 ° C.), xylene (boiling point) Aromatic hydrocarbons such as n-hexane (boiling point 69 ° C.), n-heptane (boiling point 98 ° C.), cyclohexane (boiling point 80.74 ° C.); chloroform (boiling point 61.degree. C.). 2 ° C), dichloromethane (boiling point 40 ° C), halogenated hydrocarbons such as carbon tetrachloride (boiling point 76.8 ° C); diethyl ether (boiling point 35 ° C), diethylene glycol dimethyl ether (boiling point 162 ° C), 1,4-dioxane (Boiling point 101.1 ° C.) and the like, and particularly from the viewpoint of suppressing tar-like precipitates, n-hexane, n-heptane, Aliphatic hydrocarbons such as cyclohexane are preferred.
Only one organic solvent may be used alone, or two or more organic solvents may be used in combination.
The addition amount of the organic solvent is preferably in the range of 0.1 × 10 ^{−3 to} 0.2 mol, more preferably 0.2 × 10 ^{−3 to} 0.5 × 10 ⁻¹ mol, relative to 1 mol of trioxane described later. It is a range, More preferably, it is the range of 0.5 * 10 < ^-3 > -0.3 * 10 < ^-1 > mol.
When the addition amount of the organic solvent is within the above range, the amount of scale generated in the supply part of the polymerization reactor can be reduced, and a copolymer can be obtained in a high yield.

(Materials used in the polymerization reaction process)
In the manufacturing method of the polyacetal copolymer of this embodiment, the said pre-mixed liquid and trioxane are supplied to a polymerization reactor, and a polymerization reaction is performed.
Materials used in the step of performing the polymerization reaction will be described below.

<Trioxane>
Trioxane is a cyclic trimer of formaldehyde, and is generally obtained by reacting a formalin aqueous solution in the presence of an acidic catalyst.
Since this trioxane may contain impurities that cause chain transfer such as water, methanol, formic acid, and methyl formate, as a pre-stage of the polymerization reaction step, for example, these impurities are removed and purified by a method such as distillation. It is preferable to do.
In that case, the total amount of the impurities to be chain-transferred is preferably 1 × 10 ⁻³ mol or less, more preferably 0.5 × 10 ⁻³ mol or less with respect to 1 mol of trioxane.
By reducing the amount of the impurities as shown in the above numerical values, the polymerization reaction rate can be sufficiently increased practically, and excellent thermal stability can be obtained in the produced polymer.

<Low molecular weight acetal compound>
In the step of carrying out the polymerization reaction, a low molecular weight acetal compound may be used.
The low molecular weight acetal compound functions as a chain transfer agent in the polymerization step described later, and is an acetal compound having a molecular weight of 200 or less, preferably 60 to 170.
Examples of the low molecular weight acetal compound include, but are not limited to, methylal, methoxymethylal, dimethoxymethylal, and trimethoxymethylal.
These may be used alone or in combination of two or more.
The addition amount of the low molecular weight acetal compound is in the range of 0.1 × 10 ^{−4 to} 0.6 × 10 ⁻² mol with respect to 1 mol of the trioxane from the viewpoint of controlling the molecular weight of the polyacetal copolymer to a suitable range. preferable.
The low molecular weight acetal is a method of mixing all of the trioxane and supplying it to the polymerization reactor, a method of mixing all of the premixed liquid described later and supplying it to the polymerization reactor, and partially mixing the trioxane into the polymerization reactor. You may use by any method of the method of supplying, mixing the remaining whole quantity with a pre-mixed liquid, and supplying to a polymerization machine. In particular, from the viewpoint of uniform dispersion, a method in which half or more of the low molecular weight acetal compound is mixed with trioxane is preferable.

(Step of obtaining a pre-mixed solution)
In the method for producing a polyacetal copolymer of the present embodiment, the cyclic ether and / or cyclic formal, the polymerization catalyst, and the general formula (1) are shown as the previous stage of the step of performing the polymerization reaction described later. At least one alcohol is mixed in advance to obtain a premixed solution.

Specific methods for obtaining the pre-mixed solution include the following methods 1 to 3 and the like.
1: A method of mixing a polymerization catalyst, at least one alcohol represented by the general formula (1), and cyclic ether and / or cyclic formal.
2: A method of mixing at least one alcohol represented by the general formula (1) with the cyclic ether and / or cyclic formal, and then mixing with a polymerization catalyst.
3: A method in which at least one alcohol represented by the general formula (1) and a polymerization catalyst are mixed and then mixed with the cyclic ether and / or the cyclic formal.

In the step of obtaining the pre-mixed solution, the cyclic ether and / or cyclic formal may be added to the pre-mixed solution in whole, or part of the cyclic ether and / or cyclic formal may be added to the pre-mixed solution and the remaining amount in the polymerization reaction step. You may mix in the trioxane to be used.
In addition, after supplying the pre-mixed solution, while supplying the pre-mixed solution to the polymerization reactor for performing the polymerization reaction described later, in order to maintain the uniformity of the pre-mixed solution, mix thoroughly It is necessary to keep.
Examples of the mixing method include a method of continuously joining and mixing in a pipe, a method of continuously mixing in a pipe, and then mixing in a static mixer, a method of mixing in a container equipped with a stirrer, and the like. In particular, a method of continuously joining in a pipe and then mixing with a static mixer is preferable.

  As a method for obtaining the pre-mixed solution, among the methods 1 to 3, the operation 1 is preferable from the viewpoint of simplicity of operation, and the flow can be simplified. From the viewpoint of uniform mixing, operation 2 is particularly preferable, and stable operation is possible over a long period of time.

Moreover, as temperature which implements the process of obtaining a pre-mixed liquid, the range exceeding 0 degreeC and less than 60 degreeC is preferable.
By performing pre-mixing in the temperature range, it is possible to perform a mixing process at a low cost, suppress a sudden increase in viscosity, and enable long-term stable operation.
Moreover, as time to implement the process of obtaining a pre-mixed liquid, the range of 0.01-120 minutes is preferable, More preferably, it is the range of 0.01-60 minutes.
By setting the pre-mixing time within the above range, the materials are sufficiently mixed, and an abrupt increase in viscosity of the mixture is suppressed, thereby enabling long-term stable operation.

  The pre-mixed solution obtained by the step of obtaining the pre-mixed solution and the trioxane are supplied to a polymerization reactor that performs a polymerization step described later.

In addition, you may use a polymerization catalyst in the state previously mixed with the predetermined organic solvent.
The temperature at which the polymerization catalyst and the organic solvent are mixed is in the range of 15 ° C. or higher and lower than the boiling point of the organic solvent, preferably 25 ° C. or higher and lower than the boiling point of the organic solvent, and 35 ° C. or higher and the boiling point of the organic solvent. It is less than the range.
Generation of tar-like precipitates can be suppressed by mixing at 15 ° C. or higher, and volatilization of the organic solvent can be prevented by mixing below the boiling point of the organic solvent.

(Process for conducting polymerization reaction)
In the method for producing the polyacetal copolymer of the present embodiment, the premixed solution obtained as described above, the trioxane, and, if necessary, a low molecular weight acetal compound are supplied to a polymerization reactor, and a polymerization reaction is performed. To obtain a polyacetal copolymer.
As a polymerization method of the polyacetal copolymer, any of a slurry method, a bulk method, and a melt method may be used.

  Also, the shape (structure) of the polymerization reactor to be used is not particularly limited, and any of a biaxial paddle type and a screw type stirring and mixing type polymerization apparatus capable of passing a heat medium through the jacket are suitably used. it can.

The temperature of the polymerization reactor in the step of carrying out the polymerization reaction is preferably maintained at 63 to 135 ° C, more preferably in the range of 70 to 120 ° C, and further preferably in the range of 70 to 100 ° C.
The residence (reaction) time in the polymerization reactor is preferably 0.1 to 30 minutes, more preferably 0.1 to 25 minutes, and further preferably 0.1 to 20 minutes.
If the temperature and residence time of the polymerization reactor are within the above ranges, a stable polymerization reaction tends to be continued.

By the step of performing the polymerization reaction, first, a crude polyacetal copolymer is obtained, and a target polyacetal copolymer is obtained by performing post-treatment such as deactivation treatment.
As a method for deactivating the polymerization catalyst, the crude polyacetal copolymer discharged from the polymerization reactor is converted into amines such as ammonia, triethylamine, tri-n-butylamine, alkali metal or alkaline earth metal hydroxides, inorganic salts. And an aqueous solution containing at least one neutralization deactivator such as an organic acid salt or an organic solution, and continuously stirred in a slurry state for several minutes to several hours at room temperature to 100 ° C. or less. .
At this time, when the crude polyacetal copolymer is a large lump, it is preferably pulverized after the polymerization.
Then, the target polyacetal copolymer is obtained by filtering with a centrifuge and drying under nitrogen.
In addition to the above components, other copolymer components that can form a block, branched, or crosslinked structure can be used in combination in the polymerization reaction of the polyacetal copolymer of the present embodiment.

Hereinafter, the present invention will be described with reference to specific examples and comparative examples. However, the present invention is not limited to the following examples.
In addition, the measuring method of the characteristic in an Example and a comparative example was as follows.

(Polymerization yield)
In Examples and Comparative Examples described later, the amount of crude polyacetal copolymer discharged from the polymerization reactor was calculated by dividing the amount discharged per unit time by the feed amount per unit time of all monomers.
The polymerization yield was calculated 1 hour and 240 hours after the start of polymerization.

[Polymer supply section scale status]
In Examples and Comparative Examples described later, the polymerization reactor after completion of continuous operation was opened, and the scale state of the supply unit was visually confirmed.
It was judged that the operation was stable when the scale was small.
If there is no scale or slightly: ○
If a stable yield could not be maintained due to the occurrence of scale: ×
Between ○ and ×: △

[Confirmation of colored substance generation in polymerization machine]
In Examples and Comparative Examples described later, the polymerization reactor after completion of continuous operation was opened and visually confirmed.
The color of the polyacetal copolymer attached to the barrel of the polymerization reactor was evaluated as follows.
When white polyacetal copolymer is attached: ○
When a polyacetal copolymer colored brown or yellow is attached: x

[Example 1]
A jacketed biaxial paddle-type continuous polymerization reactor (Kurimoto Kakosho, diameter 2B, L / D = 14.8) through which a heat medium can pass was adjusted to 80 ° C.
Boron trifluoride-di-n-butyl etherate 0.18 g / hr as a polymerization catalyst, methanol 0.025 g / hr as an alcohol, cyclohexane (boiling point: 80.74 ° C.) 6.5 g / hr as an organic solvent, 1,3-dioxolane 120.9 g / hr as cyclic ether and / or cyclic formal was continuously premixed at a temperature of 50 ° C. and a mixing time of 2 minutes to obtain a premixed solution.
A static mixer was used for the preparation of the pre-mixed solution.
The pre-mixed liquid 127.61 g / hr was continuously supplied to the polymerization reactor by piping, and a trioxane mixture of trioxane 3500 g / hr and methylal 3.9 g / hr, which is a low molecular weight acetal compound, was supplied to the piping. The polymer was continuously supplied to the polymerization reactor and polymerized to obtain a crude polyacetal copolymer.
The crude polyacetal copolymer discharged from the polymerization reactor was sampled in an aqueous triethylamine solution (0.5% by mass), and then stirred at room temperature for 1 hr, filtered with a centrifugal separator, and then under nitrogen. The polyacetal copolymer was obtained by drying at 120 ° C. for 3 hours.
The polymerization yield of the obtained polyacetal copolymer was evaluated after 1 hr and 240 hr after the start of polymerization.
Moreover, the coloring substance production | generation condition after 240-hour driving | operation and the scale condition of the superposition | polymerizer supply part were confirmed visually.
The evaluation results are shown in Table 1.

[Examples 2 to 11]
The raw material composition and the premixed solution preparation conditions were changed as shown in Table 1 below.
Other conditions were the same as in Example 1, and a polyacetal copolymer was obtained.
The evaluation results are shown in Table 1 below.

Example 12
Using the same polymerization reactor as that of Example 1, 0.025 g / hr of methanol as alcohols and 120.9 g / hr of 1,3-dioxolane as cyclic ether and / or cyclic formal were used. Mixed continuously.
A static mixer was used for mixing.
Next, boron trifluoride-di-n-butyl etherate 0.18 g / hr as a polymerization catalyst, cyclohexane (boiling point: 80.74 ° C.) 6.5 g / hr as an organic solvent, and continuously mixed for 2 minutes. Premixing was performed to obtain a premixed solution.
A static mixer was used for the preparation of the pre-mixed solution.
The pre-mixed liquid 127.61 g / hr was continuously supplied to the polymerization reactor through a pipe, and a trioxane mixture of trioxane 3500 g / hr and methylal 3.9 g / hr as a low molecular weight acetal compound was supplied to the pipe. The polymer was continuously supplied to the polymerization reactor and polymerized to obtain a crude polyacetal copolymer.
Other operations were the same as in Example 1, and a polyacetal copolymer was obtained.

[Examples 13 to 15]
The raw material composition and the premixed solution preparation conditions were changed as shown in Table 1 below.
Other conditions were the same as in Example 12, and a polyacetal copolymer was obtained.
The evaluation results are shown in Table 1 below.

Example 16
Using the same polymerization reactor as in Example 1, methanol was 0.025 g / hr as the alcohol, boron trifluoride-di-n-ethyl etherate was 0.18 g / hr as the polymerization catalyst, and 1,4- Dioxane (boiling point: 80.74 ° C.) 6.5 g / hr was first continuously mixed at a temperature of 50 ° C.
A static mixer was used for mixing.
Next, 120.9 g / hr of 1,3-dioxolane as a cyclic ether and / or cyclic formal was continuously premixed at a mixing time of 2 minutes to obtain a premixed solution.
A static mixer was used for the pre-mixing.
The pre-mixed liquid 127.61 g / hr was continuously supplied to the polymerization reactor via a pipe, and a trioxane mixture consisting of trioxane 3500 g / hr and methylal 3.9 g / hr as a low molecular weight acetal compound was The polymer was continuously supplied to the polymerization reactor and polymerized to obtain a crude polyacetal copolymer. Other operations were carried out in the same manner as in Example 1 to obtain a polyacetal copolymer.

[Comparative Example 1]
A jacketed biaxial paddle-type continuous polymerization reactor (Kurimoto Kakosho, diameter 2B, L / D = 14.8) through which a heat medium can pass was adjusted to 80 ° C.
Boron trifluoride-di-n-butyl etherate 0.18 g / hr as a polymerization catalyst is first fed continuously to the reactor at a temperature of 50 ° C., then 1 as cyclic ether and / or cyclic formal. , 3-Dioxolane 120.9 g / hr was continuously premixed at a temperature of 50 ° C. and a mixing time of 2 minutes to obtain a premixed solution.
A static mixer was used for the pre-mixing.
121.08 g / hr of the pre-mixed solution was continuously supplied to the polymerization reactor through a pipe, and a trioxane mixture consisting of 3500 g / hr of trioxane and 3.9 g / hr of methylal as a low molecular weight acetal compound was polymerized through the pipe. Polymerization was carried out by continuously supplying to the reactor to obtain a crude polyacetal copolymer.
The crude polyacetal copolymer discharged from the polymerization reactor was sampled in an aqueous triethylamine solution (0.5% by mass), and then stirred at room temperature for 1 hr, filtered through a centrifuge, and 120 ° under nitrogen. The polyacetal copolymer was obtained by drying at ° C. for 3 hours.
The polymerization yield of the obtained polyacetal copolymer was evaluated 1 hour after the start of polymerization.
In addition, the polymerization was stopped because the pre-mixed liquid feeding became unstable after the 2 hr operation.
After the stop, the scale condition of the polymerization machine supply unit was visually confirmed.
The evaluation results are shown in Table 2 below.

[Comparative Example 2]
A jacketed biaxial paddle-type continuous polymerization reactor (Kurimoto Kakosho, diameter 2B, L / D = 14.8) through which a heat medium can pass was adjusted to 80 ° C.
First, boron trifluoride-di-n-butyl etherate 0.18 g / hr as a polymerization catalyst and cyclohexane (boiling point: 80.74 ° C.) 6.5 g / hr as an organic solvent, first at a temperature of 50 ° C. To obtain a catalyst solution.
6.68 g / hr of the catalyst solution is continuously supplied to the polymerization reactor by piping, 1,3-dioxolane is used as cyclic ether and / or cyclic formal, 120.9 g / hr, and trioxane is 3500 g / hr, A trioxane mixture consisting of 3.9 g / hr of methylal as a low molecular weight acetal compound was continuously supplied to the polymerization reactor via a pipe and polymerized to obtain a crude polyacetal copolymer.
The crude polyacetal copolymer discharged from the polymerization reactor was sampled in an aqueous triethylamine solution (0.5% by mass), and then stirred at room temperature for 1 hr, filtered through a centrifuge, and 120 ° under nitrogen. The polyacetal copolymer was obtained by drying at ° C. for 3 hours.
The polymerization yield of the obtained polyacetal copolymer was evaluated after 1 hr and 240 hr after the start of polymerization.
In addition, the polymerization stability after 240 hr operation and the scale condition of the polymerization machine supply unit were visually confirmed. The evaluation results are shown in Table 2.

[Comparative Example 3]
The raw material composition was changed as shown in Table 2 below.
Other conditions were the same as in Example 1, and a polyacetal copolymer was obtained.
The evaluation results are shown in Table 2 below.

As shown in Tables 1 and 2, in Examples 1 to 16, there is little generation of scale in the polymerization apparatus supply section after long-term operation, and high-quality polyacetal copolymers are stably produced for a long period of time with a high polymerization yield. Thus, stable and continuous production was possible for a long time.
In Comparative Example 1, the supply of the raw material became unstable in the middle, and it was difficult to continue the polymerization for 2 hours.
In Comparative Example 2, since the raw materials were separately supplied to the polymerization machine without performing pre-mixing, the scale of the polymerization apparatus supply section increased, and long-term stable operation was not performed.
In Comparative Example 3, a coloring substance was generated in the polymerization machine.

  The method for producing a polyacetal copolymer of the present invention is an industrial method which enables production of a polyacetal copolymer stably at a high polymerization yield for a long period of time while maintaining the polymerization yield even with a small amount of polymerization catalyst. There is a possibility of use.

Claims (9)

A method for producing a polyacetal copolymer for polymerizing trioxane with a cyclic ether and / or a cyclic formal,
The cyclic ether and / or cyclic formal;
A polymerization catalyst;
At least one alcohol represented by the following general formula (1);
To obtain a pre-mixed solution,
Supplying the premixed solution and the trioxane to a polymerization reactor, and performing a polymerization reaction;
The manufacturing method of the polyacetal copolymer which has these.
R— (CH ₂ —O) _n —H (1)
(In General Formula (1), R represents any one selected from the group consisting of hydrogen, a branched or linear alkyl group, a branched or linear alkoxy group, and a hydroxyl group. Represents an integer of 1 to 20.) A step of previously mixing the alcohol represented by the general formula (1) with the cyclic ether and / or the cyclic formal, and then mixing the polymerization catalyst to obtain the premixed solution;
Supplying the premixed solution and the trioxane to a polymerization reactor, and performing a polymerization reaction;
The manufacturing method of the polyacetal copolymer of Claim 1 which has these. A step of previously mixing the alcohol represented by the general formula (1) with a polymerization catalyst, and then mixing the cyclic ether and / or cyclic formal to obtain the pre-mixed solution;
Supplying the premixed solution and the trioxane to a polymerization reactor, and performing a polymerization reaction;
The manufacturing method of the polyacetal copolymer of Claim 1 which has these. In the step of obtaining the pre-mixed solution, an organic solvent is further used,
The method for producing a polyacetal copolymer according to any one of claims 1 to 3, wherein the polymerization catalyst is mixed under a temperature condition of 25 ° C or higher and lower than the boiling point of the organic solvent.   5. The method according to claim 1, wherein the polymerization catalyst is at least one selected from the group consisting of boron trifluoride, boron trifluoride diethyl etherate, and boron trifluoride-di-n-butyl etherate. A process for producing the polyacetal copolymer according to claim 1.   The method for producing a polyacetal copolymer according to claim 4 or 5, wherein the organic solvent is at least one selected from the group consisting of n-hexane, n-heptane, and cyclohexane.   The method for producing a polyacetal copolymer according to any one of claims 1 to 6, wherein a part of at least one alcohol represented by the general formula (1) is mixed with the trioxane.   At least one alcohol represented by the general formula (1) is methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-1 The method for producing a polyacetal copolymer according to any one of claims 1 to 7, which is any one selected from the group consisting of -propanol and 2-methyl-2-propanol. At least one alcohol represented by the general formula (1) is:
The manufacturing method of the polyacetal copolymer as described in any one of Claims 1 thru | or 8 used in the range of 0.01 mol or more and 100 mol or less with respect to 1 mol of said polymerization catalysts.