JP6438270B2 - Process for producing polyacetal copolymer - Google Patents

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 polyacetal copolymers is also remarkable, and there is a high demand for polymer-type polyacetal copolymers, and there is a demand for a method for producing polymer-type polyacetal copolymers with high productivity. .

  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 during the polymerization of the polyacetal copolymer is important for stabilizing the quality of the parts using the polyacetal copolymer. As a cause that hinders long-term stable operation during polymerization, first, it is impossible to supply a stable raw material due to 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, and a polymerization catalyst are mixed in advance, A technique for adding and supplying to trioxane for polymerization (for example, see Patent Document 1), a technique in which a cyclic ether and / or cyclic formal, a polymerization catalyst, and an organic solvent are mixed in advance and brought into contact with trioxane for polymerization ( For example, see 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, the polyacetal copolymer obtained is substantially only a low molecular weight polyacetal copolymer, as described in the Examples of Patent Document 1, for example, a melt index measured at 190 ° C. is 50 g / There is no description about manufacturing a product of 10 min or less.

  Therefore, in the present invention, the generation of scale can be reduced, and a high-quality, high-molecular weight type polyacetal copolymer can be stably and continuously produced 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 that can maintain the polymerization yield over a long period of time.

As a result of intensive studies by the present inventors in order to solve the above-mentioned problems, a polyacetal copolymer that performs polymerization by supplying trioxane, a cyclic ether and / or a cyclic formal, and a polymerization catalyst to a polymerization reactor and performing polymerization is provided. In the production method, a premixed solution in which the cyclic ether and / or cyclic formal, the polymerization catalyst, a predetermined low molecular weight acetal, an organic solvent, and an antioxidant are mixed in advance is obtained. It has been found that the above-mentioned problems of the prior art can be solved by supplying the mixed solution and trioxane to the polymerization reactor and carrying out the polymerization reaction, thereby completing the present invention.
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,
A polymerization catalyst, an organic solvent and an antioxidant are mixed in advance,
Thereafter, a low molecular weight acetal represented by the following general formula (1) is mixed with the cyclic ether and / or cyclic formal to obtain a pre-mixed solution;
R— (CH ₂ —O) _n —R (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. Is 1
Represents an integer of 20 or more. )
Before Symbol pre mixed solution, and the trioxane, comprising the steps of supplying to both polymerization reactor, conduct the polymerization reaction,
The manufacturing method of the polyacetal copolymer which has these.
[2]
The method for producing a polyacetal copolymer according to [1] , wherein a polyacetal copolymer having a melt index of 0.1 g / 10 min to 50 g / 10 min is produced.
[3]
The polymerization catalyst is mixed under a temperature condition of 25 ° C. or higher and lower than the boiling point of the organic solvent,
[ 1] A process for producing the polyacetal copolymer according to [2] .
[4]
[1] to [3 ], 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.
[5]
The method for producing a polyacetal copolymer according to any one of [1] to [4] , wherein the organic solvent is at least one selected from the group consisting of n-hexane, n-heptane, and cyclohexane.
[6]
The whole amount of the low molecular weight acetal represented by the general formula (1) is mixed with the pre-mixture, or a part of the low molecular weight acetal represented by the general formula (1) is mixed with the trioxane,
The method for producing a polyacetal copolymer according to any one of [1] to [5] , wherein the remaining amount is mixed with the pre-mixed solution.
[7]
The method for producing a polyacetal copolymer according to any one of [1] to [6] , wherein the antioxidant is a phenolic antioxidant.

  According to the method for producing a polyacetal copolymer of the present invention, generation of scale can be reduced, and a high-quality, high-molecular-weight type polyacetal copolymer can be stably produced continuously for a long period of time with a high polymerization yield. In addition, the polymerization yield can be maintained over a long period even with a small amount of polymerization catalyst.

  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:
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;
A low molecular weight acetal represented by the following general formula (1):
R— (CH ₂ —O) _n —R (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.)
An organic solvent,
An antioxidant,
To obtain a pre-mixed solution,
Supplying the pre-mixed solution and the trioxane together to a polymerization reactor to perform a polymerization reaction;
Have

(Materials used in the method for producing the polyacetal copolymer of the present embodiment)
The material used in the manufacturing method of the polyacetal copolymer of this embodiment is demonstrated.
<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.

<Cyclic ether and / or cyclic formal>
Cyclic ether and / or cyclic formal is a component copolymerizable with the trioxane.
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 the cyclic formal is preferably in the range of 1 × 10 ^{−2 to} 20 × 10 ⁻² mol, more preferably 1 × 10 ⁻² mol with respect to 1 mol of the trioxane, from the viewpoint of mechanical strength. It is ˜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 × 10, with respect to 1 mol of the trioxane. ^-4 mol, more preferably 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.
In addition, the addition amount of the polymerization catalyst within the above range is a remarkably small amount as compared with the addition amount of the polymerization catalyst when a boron trifluoride-based polymerization catalyst is used in the prior art.

<Low molecular weight acetal represented by general formula (1)>
In the method for producing a polyacetal copolymer of the present embodiment, a low molecular weight acetal represented by the following general formula (1) is used.
R— (CH ₂ —O) _n —R (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.)
The low molecular weight acetal functions as a chain transfer agent in the polymerization step described later, and is an acetal having a molecular weight of 200 or less, preferably 60 to 170.
By using the acetal having the above molecular weight, the molecular weight of the final polyacetal copolymer can be adjusted.
Examples of the low molecular weight acetal represented by the general formula (1) include, but are not limited to, methylal, methoxymethylal, dimethoxymethylal, trimethoxymethylal, and the like. These may be used alone or in combination of two or more.

In the method for producing a polyacetal copolymer of the present embodiment, the amount of the low molecular weight acetal represented by the general formula (1) is controlled from the viewpoint of controlling the molecular weight of the target polyacetal copolymer within a suitable range. The range of 0.1 × 10 ^{−4 to} 0.6 × 10 ⁻² mol is preferable with respect to 1 mol of trioxane, the range of 0.1 × 10 ^{−4 to} 0.6 × 10 ⁻³ mol is more preferable, and The range of 1 × 10 ^{−4 to} 0.1 × 10 ⁻³ mol is more preferable.

  The low molecular weight acetal represented by the general formula (1) is a method in which the entire amount is mixed with the pre-mixture and supplied to the polymerization machine, partly mixed with the trioxane and supplied to the mixer, and the remaining total amount is mixed with the pre-mixture. Then, there is a method of supplying to the polymerization machine, and any method may be selected. In particular, from the viewpoint of uniform dispersion, it is preferable to mix at least half of the low molecular weight acetal with trioxane.

<Organic solvent>
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 and 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 in the range of 0.2 × 10 ^{−3 to} 0.5 × 10 ⁻¹ mol, relative to 1 mol of the trioxane. More preferably, it is in the range of 0.5 × 10 ^{−3 to} 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.

<Antioxidant>
Although it does not specifically limit as antioxidant, A phenolic antioxidant can be used.
Examples of the phenol-based antioxidant include, but are not limited to, for example, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate, n -Octadecyl-3- (3'-methyl-5'-t-butyl-4'-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5'-di-t-butyl-4'-hydroxy Phenyl) -propionate, 1,6-hexanediol-bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate], 1,4-butanediol-bis- [3- ( 3,5-di-t-butyl-4-hydroxyphenyl) -propionate], 2,2′-methylenebis- (4-methyl-t-butylphenol), triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate], tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, 3 9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] 2,4,8,10-tetraoxaspiro (5 5) Undecane, N, N′-bis-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionylhexamethylenediamine, N, N′-tetramethylene-bis-3- (3′-Methyl-5′-t-butyl-4′-hydroxyphenol) propionyldiamine, N, N′-bis- [3- (3,5-di-t-butyl-4-hydroxyphenol) propionyl] Dorazine, N-salicyloyl-N′-salicylidenehydrazine, 3- (N-salicyloyl) amino-1,2,4-triazole, N, N′-bis [2- {3- (3,5-di- t-butyl-4-hydroxyphenyl) propionyloxy} ethyl] oxyamide and the like. Preferably, triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] and tetrakis [methylene-3- (3 ′, 5′-di-t-butyl) -4'-hydroxyphenyl) propionate] methane. These antioxidants may be used alone or in combination of two or more.
Moreover, it is preferable to use 0.001-1 mass part for antioxidant with respect to 100 mass parts of the said cyclic ether and / or cyclic formal.
By using an antioxidant, it is possible to suppress an unintended decrease in molecular weight in the polymerization step.

(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. A low molecular weight acetal, the organic solvent, and the antioxidant are mixed in advance to obtain a premixed solution.

Specific methods for obtaining the pre-mixed solution include the following methods 1 to 4 and the like.
1: A method in which an antioxidant and an organic solvent are mixed, then mixed with a polymerization catalyst, and then a cyclic ether and / or cyclic formal and a low molecular weight acetal represented by the general formula (1) are mixed.
2: A method of mixing a polymerization catalyst, an antioxidant, and an organic solvent, mixing a low molecular weight acetal represented by the general formula (1), and then mixing the cyclic ether and / or the cyclic formal.
3: A method of mixing the cyclic ether and / or cyclic formal, an antioxidant and an organic solvent, and then mixing a polymerization catalyst and a low molecular weight acetal represented by the general formula (1).
4: A method of mixing the cyclic ether and / or cyclic formal, an antioxidant and a low molecular weight acetal represented by the general formula (1), and then mixing a polymerization catalyst and an organic solvent.

In the step of obtaining the pre-mixed solution, in particular, from the viewpoint of suppressing an unintended molecular weight decrease of the polyacetal copolymer obtained by polymerization, the cyclic ether and / or cyclic formal and the low formula represented by the general formula (1) are used. It is preferred to mix the antioxidant before contacting the molecular weight acetal directly.
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 joining in a pipe and then mixing with a static mixer, a method of mixing in a container equipped with a stirrer, and the like. In particular, a method in which continuous merging is performed in the pipe and then mixed using a static mixer is preferable.

  As a method for obtaining the pre-mixed solution, among the methods 1 to 4, the operation 1 is preferable from the viewpoint of the ease 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 liquid obtained as described above, the trioxane, and, if necessary, a low molecular weight acetal 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.

  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 suitable. Can be used.

The temperature of the polymerization reactor in the step of carrying out the polymerization reaction is preferably maintained in the range of 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 in the step of performing the polymerization reaction is preferably 0.1 to 30 minutes, more preferably 0.1 to 25 minutes, and further preferably 0.1 to 20 minutes. It is.
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 above-described 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 deactivation treatment method for the polymerization catalyst, the crude polyacetal copolymer discharged from the polymerization reactor is converted to amines such as ammonia, triethylamine, tri-n-butylamine, alkali metal or alkaline earth metal hydroxide, inorganic An example is a method in which an aqueous solution or an organic solution containing at least one neutralization deactivator such as a salt or an organic acid salt is charged and continuously stirred in a slurry state for several minutes to several hours at room temperature to 100 ° C. or less. It is done.
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.

The polyacetal copolymer obtained by the method for producing the polyacetal copolymer of the present embodiment preferably has a melt index of 0.1 g / 10 min to 50 g / 10 min, preferably 0.1 g / 10 min to 40 g / 10 min. More preferably, it is 0.1 g / 10min or more and 30 g / 10min or less. When the melt index is 0.1 g / 10 min or more, sufficient mechanical properties are obtained, and when it is 50 g / 10 min or less, good moldability is obtained.
The melt index of the polyacetal copolymer can be measured by the method described in Examples described later.

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 evaluation method and the characteristic measurement method in the examples and comparative examples were 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.

<Scale condition of polymerizer supply section>
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.
When there is no scale or slightly: ○
If a stable yield could not be maintained due to the occurrence of scale: ×
Between ○ and ×: △

<Confirmation of the colored substance generation in the 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 co-polymer colored brown or yellow is attached: x

<Measurement of melt index of polyacetal copolymer>
Measurements were performed according to ASTM D-1238.
The measurement temperature was 190 ° C.

[ Reference Example 1]
Two-axis paddle type continuous polymerization reactor with jacket through which heat medium can pass (manufactured by Kurimoto Steel Works,
The diameter 2B (2 inches) and L (distance from the raw material supply port to the discharge port of the polymerization reactor) / D (inner diameter of the polymerization reactor) = 14.8) were adjusted to 80 ° C.
An organic solvent mixed solution (I) was prepared by using cyclohexane (boiling point: 80.74 ° C.) as an organic solvent and Irganox 1010 as an antioxidant in a mass ratio of organic solvent: antioxidant = 540: 1.
Then, boron trifluoride-di-n-butyl etherate as a polymerization catalyst was 0.18 g /
hr, 0.24 g / hr of methylal as a low molecular weight acetal, the organic solvent mixture (
I) is 6.50 g / hr, cyclic ether and / or cyclic formal and 1,3-dioxone is 120.9 g / hr continuously at a temperature of 30 ° C. and a mixing time of 2 minutes. A liquid was obtained.
In addition, the static mixer was used for preparation of the said pre-mixed liquid.
The pre-mixed liquid (I) was continuously supplied to the polymerization reactor by piping at 127.82 g / hr, and trioxane was continuously supplied to the polymerization reactor by piping at 3500 g / hr. And a crude polyacetal copolymer was obtained.
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 below.

[ Reference Examples 2 to 5]
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 Reference Example 1 to obtain a polyacetal copolymer.
The evaluation results are shown in Table 1 below.

Example 6
A jacketed biaxial paddle type continuous polymerization reactor (manufactured by Kurimoto Steel Works, diameter 2B, L / D = 14.8) through which a heat medium can pass was adjusted to 80 ° C.
Boron trifluoride-di-n-butyl etherate as a polymerization catalyst, cyclohexane as an organic solvent, and Irganox 1010 as an antioxidant, in a mass ratio, polymerization catalyst: organic solvent: antioxidant = 15: 300 An organic solvent mixed solution (II) having a ratio of 1 was prepared.
Subsequently, 0.24 g / hr of methylal as a low molecular weight acetal, 3.79 g / hr of the organic solvent mixed solution (II), 120.9 g / hr of 1,3-dioxolane as a cyclic ether and / or cyclic formal, Continuous pre-mixing at a temperature of 30 ° C. and a mixing time of 2 minutes gave a pre-mixed solution.
In addition, the static mixer was used for preparation of the said pre-mixed liquid.
The pre-mixed liquid was continuously supplied to the polymerization reactor at 124.93 g / hr by piping, and trioxane was continuously supplied to the polymerization reactor by piping at 3500 g / hr to conduct polymerization. A polyacetal copolymer was obtained.
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 below.

[ Reference Example 7]
Two-axis paddle type continuous polymerization reactor with jacket through which heat medium can pass (manufactured by Kurimoto Steel Works,
Diameter 2B, L / D = 14.8) was adjusted to 80 ° C.
1,3-dioxolane as a cyclic ether and / or cyclic formal, Irganox 1010 as an antioxidant, and cyclohexane as an organic solvent, in terms of mass ratio, cyclic ether and / or cyclic formal: antioxidant: organic solvent = An organic solvent mixed solution (III) having a ratio of 10,000: 1: 300 was prepared.
Subsequently, 0.24 g / hr of methylal as a low molecular weight acetal, 123.61 g / hr of the organic solvent mixed solution (III), and 0.18 g / hr of boron trifluoride-di-n-butyl etherate as a polymerization catalyst. And continuously premixed at a temperature of 30 ° C. and a mixing time of 2 minutes,
A premixed solution was obtained.
In addition, the static mixer was used for preparation of the said pre-mixed liquid.
The pre-mixed solution is continuously supplied to the polymerization reactor at 124.03 g / hr by piping, trioxane is continuously supplied to the polymerization reactor by 3500 g / hr by piping, and polymerization is performed.
A crude polyacetal copolymer was obtained.
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 below.

[ Reference Example 8]
Two-axis paddle type continuous polymerization reactor with jacket through which heat medium can pass (manufactured by Kurimoto Steel Works,
Diameter 2B, L / D = 14.8) was adjusted to 80 ° C.
1,3-dioxolane as a cyclic ether and / or cyclic formal, Irganox 1010 as an antioxidant, and methylal as a low molecular weight acetal, in a mass ratio,
Cyclic ether and / or cyclic formal: Antioxidant: Low molecular weight acetal = 10000
A mixed solution (IV) having a ratio of 1:20 was prepared.
Subsequently, 120.25 g / hr of the mixed solution (IV), 4.2 g / hr of cyclohexane as an organic solvent, and 0.03 of boron trifluoride-di-n-butyl etherate as a polymerization catalyst.
The mixture was continuously premixed at a temperature of 30 ° C. and a mixing time of 2 minutes at 18 g / hr to obtain a premixed solution.
In addition, the static mixer was used for preparation of the said pre-mixed liquid.
The pre-mixed solution is continuously supplied to the polymerization reactor at 124.63 g / hr by piping, and trioxane is continuously supplied to the polymerization reactor by piping at 3500 g / hr to perform polymerization.
A crude polyacetal copolymer was obtained.
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 below.

[Comparative Example 1]
A jacketed biaxial paddle type continuous polymerization reactor (manufactured by Kurimoto Steel Works, diameter 2B, L / D = 14.8) through which a heat medium can pass was adjusted to 80 ° C.
Boron trifluoride-di-n-butyl etherate as a polymerization catalyst was continuously supplied to the reactor at a temperature of 50 ° C. at 0.18 g / hr, and then as a cyclic ether and / or a cyclic formal. 1,3-Dioxolane was continuously premixed at 120.9 g / hr at a temperature of 30 ° C. and a mixing time of 2 minutes to obtain a premixed solution.
A static mixer was used for the pre-mixing.
The pre-mixed solution was continuously supplied to the polymerization reactor at 121.08 g / hr via a pipe, and a trioxane mixture consisting of 3500 g / hr trioxane and 0.24 g / hr methylal as a low molecular weight acetal was polymerized via 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), then stirred at room temperature for 1 hr, filtered through a centrifuge, and 120 ° C. under nitrogen. X3 hr drying was performed to obtain a polyacetal copolymer.
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 (manufactured by Kurimoto Steel Works, diameter 2B, L / D = 14.8) through which a heat medium can pass was adjusted to 80 ° C.
1,3-dioxolane as a cyclic ether and / or cyclic formal and Irganox 1010 as an antioxidant in a mass ratio of cyclic ether and / or cyclic formal: antioxidant = 10000: 1 mixed solution (V ) Was prepared.
First, boron trifluoride-di-n-butyl etherate as a polymerization catalyst was 0.18 g / hr, and cyclohexane (boiling point: 80.74 ° C.) as an organic solvent was continuously mixed at 6.5 g / hr. A liquid was obtained.
This catalyst solution was continuously fed to the polymerization reactor by piping at 6.68 g / hr, the mixed solution (V) was 120.01 g / hr, trioxane 3500 g / hr and methylal as a low molecular weight acetal. A trioxane mixture consisting of 24 g / hr was continuously supplied to the polymerization reactor through piping, and polymerization was performed 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), then stirred at room temperature for 1 hr, filtered through a centrifuge, and 120 ° C. under nitrogen. X3 hr was dried to obtain a polyacetal copolymer.
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 below.

[Comparative Example 3]
A jacketed biaxial paddle type continuous polymerization reactor (manufactured by Kurimoto Steel Works, diameter 2B, L / D = 14.8) through which a heat medium can pass was adjusted to 80 ° C.
An organic solvent mixed solution (I) was prepared by using cyclohexane (boiling point: 80.74 ° C.) as an organic solvent and Irganox 1010 as an antioxidant in a mass ratio of organic solvent: antioxidant = 540: 1. .
Next, 0.18 g / hr of boron trifluoride-di-n-butyl etherate as a polymerization catalyst, 6.50 g / hr of the organic solvent mixed solution (I), 1,3 as cyclic ether and / or cyclic formal -Dioxolane was continuously premixed at 120.9 g / hr at a temperature of 30 ° C and a mixing time of 2 minutes to obtain a premixed solution.
A static mixer was used for preparing the pre-mixed solution.
3500 g / hr of trioxane and 0.24 g / hr of methylal as a low molecular weight acetal are continuously fed to the polymerization reactor after mixing through a pipe and the premixed liquid 127.82 g / hr is polymerized through a pipe. It supplied continuously to the reactor and superposed | polymerized and the crude polyacetal copolymer was obtained.
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 2 below.

As shown in Tables 1 and 2, in Reference Examples 1 to 5, Example 6, and Reference Examples 7 and 8 , there is little generation of scale in the polymerization apparatus supply section after long-term operation, and high quality is stable over a long period of time. The high molecular weight type polyacetal copolymer was able to be produced stably and continuously for a long period of time with a high polymerization yield.
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 application as a method that enables stable production of a polyacetal copolymer for a long period of time with a high polymerization yield while maintaining the polymerization yield even with a small amount of polymerization catalyst. there is a possibility.

Claims (7)

A method for producing a polyacetal copolymer for polymerizing trioxane with a cyclic ether and / or a cyclic formal,
A polymerization catalyst, an organic solvent and an antioxidant are mixed in advance,
Thereafter, a low molecular weight acetal represented by the following general formula (1) is mixed with the cyclic ether and / or cyclic formal to obtain a pre-mixed solution;
R— (CH ₂ —O) _n —R (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. Is 1
Represents an integer of 20 or more. )
Before Symbol pre mixed solution, and the trioxane, comprising the steps of supplying to both polymerization reactor, conduct the polymerization reaction,
The manufacturing method of the polyacetal copolymer which has these. Melt index is less than 0.1 g / 10min or more 50 g / 10min, to produce a polyacetal copolymer, method for producing a polyacetal copolymer according to claim 1. The method for producing a polyacetal copolymer according to claim 1 or 2 , 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. The polymerization catalyst, boron trifluoride, boron trifluoride diethyl etherate, and boron trifluoride - at least one selected from the group consisting of di -n- butyl etherate, any of claims 1 to 3 A process for producing the polyacetal copolymer according to claim 1. The method for producing a polyacetal copolymer according to any one of claims 1 to 4 , wherein the organic solvent is at least one selected from the group consisting of n-hexane, n-heptane, and cyclohexane. The whole amount of the low molecular weight acetal represented by the general formula (1) is mixed with the pre-mixture, or a part of the low molecular weight acetal represented by the general formula (1) is mixed with the trioxane,
The manufacturing method of the polyacetal copolymer as described in any one of Claims 1 thru | or 5 which mixes the remaining whole quantity with the said pre-mixed liquid. The method for producing a polyacetal copolymer according to any one of claims 1 to 6 , wherein the antioxidant is a phenol-based antioxidant.