JPH11263820A - Continuous production of polyacetal resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous production method of a polyactal resin which enables an industrial and stable production of the polyacetal resin for a long term. SOLUTION: A continuous production method of a polyacetal resin by bulk polymerization of (A) a trioxane, (B) a cyclic polyether and/or a cyclic formal and (C) a low molecular weight polyacetal compound by use of (D) a cation polymerization catalyst is characterized in that (C) the low molecular weight polyacetal compound and (D) the cation polymerization catalyst are mixed in advance and the mixture is added to (A) the trioxane or the mixture of (A) the trioxane and (B) the cyclic polyether and/or the cyclic formal followed by polymerization thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyacetal resin, and more particularly, to a method for producing a polyacetal resin stably and continuously for a long period of time on an industrial scale.

[0002]

2. Description of the Related Art Polyacetal resins are well-balanced in mechanical properties, chemical resistance, slidability, etc., and are easy to process. Widely used mainly for parts and other various mechanical parts. In the case of polyacetal resins, in particular, in an industrial continuous production method of a copolymer-type polyacetal resin, a mixing step of a monomer and a comonomer and a catalyst, and a subsequent polymerization step are often performed by one polymerization apparatus.

[0003] In this case, in the polymerization step, a viscous intermediate reaction product and a formed bulk polymerization reaction product are mixed. This adheres to the screw, paddle, etc. of the polymerization machine and applies a high load to the screw rotating shaft. Therefore, there is a limit in increasing the rotation speed of the polymerization machine. As a result, the number of rotations of the polymerization machine is not sufficient for mixing the raw material monomers and the catalyst. For example, the rotation speed of the polymerization machine causes a fluctuation of the polymerization machine torque, which is a serious problem in production. To cope with such a problem, Japanese Patent Publication No. 4-59329 proposes a method in which trioxane and a catalyst, or trioxane, a cyclic ether and a catalyst are mixed in advance by another stirring device. However, this method is not a preferable method because the apparatus becomes complicated, the cost is high, and the risk of blocking the reaction product is high.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for continuously producing a polyacetal resin stably for a long period of time on an industrial scale with little fluctuation in the torque of a polymerization machine.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and have found that trioxane, a cyclic ether and / or cyclic formal, and a low-molecular-weight acetal compound are used by using a cationic polymerization catalyst. It has been found that the above problems can be solved by performing bulk polymerization under specific conditions, and the present invention has been completed.

That is, the present invention provides bulk polymerization of (A) trioxane, (B) a cyclic ether and / or cyclic formal, and (C) a low molecular weight acetal compound using a (D) cationic polymerization catalyst to form a polyacetal resin. In the continuous production method, a mixture obtained by once mixing (C) a low molecular weight acetal compound and (D) a cationic polymerization catalyst is mixed with (A) trioxane or (A) trioxane and (B) cyclic ether and / or cyclic formal. The present invention relates to a method for continuously producing a polyacetal resin, which comprises adding and supplying a mixture to polymerize the mixture.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for producing a polyacetal resin according to the method of the present invention will be described. The polyacetal resin in the present invention is a copolymer of (A) trioxane, (B) a cyclic ether and / or cyclic formal, and (C) a low-molecular-weight acetal compound, and (D) a bulk-polymerized polyacetal resin using a cationic polymerization catalyst. Be the subject.

The basic molecular structure is not particularly limited, and includes those having a branched / crosslinked structure, those having a block component introduced, and the like. Further, its molecular weight or melt viscosity is not limited to these as long as it can be melt-molded. If specifically defined, the melt index is 0.1 to 100 g / 10 min (A
STM D1238). When the melt index exceeds 100 g / 10 min, the mechanical properties are remarkably reduced, and when the melt index is less than 0.1 g / 10 min, the fluidity of the resin becomes poor.

Examples of the cyclic ether and / or cyclic formal (B) used in the present invention include ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, epibromohydrin, styrene oxide,
Oxetane, 3,3-bis (chloromethyl) oxetane, cyclic ethers such as tetrahydrofuran, ethylene glycol formal, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, trioxepane, 1,3-
Cyclic formals such as dioxolane, and mixtures thereof. Among them, ethylene oxide, 1,3
-Dioxolane, diethylene glycol formal,
1,4-butanediol formal and the like are preferred.

The amount of the cyclic ether and / or cyclic formal (B) to be used is 0.1 or more for trioxane (A) in consideration of the rigidity and chemical resistance of the molded article. 1 to 20% by weight, preferably 0.5
１５15% by weight. (B) When the use amount of the cyclic ether and / or cyclic formal exceeds 20% by weight, mechanical strength such as rigidity of the molded product and chemical resistance are reduced, and
If it is less than 0.1% by weight, the thermal stability of the resin is undesirably reduced. Further, (B) the cyclic ether and / or cyclic formal may be used after previously diluted with another organic solvent or the like.

As the low molecular weight acetal compound (C), a continuous transfer agent which does not form an unstable terminal and is represented by the following general formula (1) is exemplified. R ¹ —O — (— CH ₂ O—) n—R ² (1) (where R ¹ and R ² are alkyl groups having 1 to 20 carbon atoms,
Each may be the same or different, and n represents an integer of 1 to 20. )

Specific compounds include, for example, one or more compounds having an alkoxy group, such as methylal, methoxymethylal, dimethoxymethylal, trimethoxymethylal, and oxymethylene di-n-butyl ether. . The amount of the (C) low molecular weight acetal compound used is preferably (A) trioxane 10
0% by weight or a combination of one or more
01 to 0.5% by weight. Further, it may be used after previously diluted with another organic solvent or the like. When the amount of the (C) low molecular weight acetal compound is more than 0.5% by weight, mechanical properties are remarkably reduced, and when the amount is less than 0.001% by weight, the fluidity of the resin is unfavorably poor.

In the production method of the present invention, in addition to the above components, other chemical components such as a component capable of forming a branched / crosslinked structure can be used in combination. Examples of the component capable of forming a branched / crosslinked structure include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, hexamethylene glycol diglycidyl ether,
Resorcinol diglycidyl ether, bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polybutylene glycol diglycidyl ether, glycerin and its alkylene oxide adduct or derivatives such as glycidyl ether, pentaerythritol and its alkylene oxide One or more of adducts and derivatives such as glycidyl ethers may be used.

The amount of the component capable of forming a branched / crosslinked structure is 0.3% by weight or less based on (A) trioxane.
Preferably, it is at most 0.2% by weight. These branches
The component capable of forming a crosslinked structure may be added to (A) trioxane, (B) cyclic ether and / or cyclic formal, or (C) low molecular weight acetal compound. Further, it may be added by diluting in advance with another organic solvent or the like.

The (D) cationic polymerization catalyst used in the present invention includes lead tetrachloride, tin tetrachloride, titanium tetrachloride, aluminum trichloride, zinc chloride, vanadium trichloride, antimony trichloride, phosphorus pentafluoride, Antimony fluoride, boron trifluoride, boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, boron trifluoride dioxanate, boron trifluoride acetic anhydrate, boron trifluoride triethylamine complex compound, Boron trifluoride coordination compound such as 1,3-dioxolane coordination compound of boron fluoride, perchloric acid, acetyl perchlorate, t-butyl perchlorate, hydroxyacetic acid, trichloroacetic acid, trifluoroacetic acid, p-toluenesulfone Inorganic and organic acids such as acids, triethyloxonium tetrafluoroborate, Complex salts such as triphenylmethylhexafluoroantimonate, allyldiazonium hexafluorophosphate, allyldiazonium tetrafluoroborate, diethylzinc, triethylaluminum, alkyl metal salts such as diethylaluminum chloride, heteropolyacid, isopolyacid, etc. or Two or more types are mentioned.

Among them, boron trifluoride, or boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, boron trifluoride dioxanate, boron trifluoride acetic unhydrate, boron trifluoride A triethylamine complex compound or a boron trifluoride coordination compound such as a 1,3-dioxolane coordination compound of boron trifluoride is preferable. These (D) cationic polymerization catalysts may be used as they are, may be diluted in advance with an organic solvent or the like, or may be used by mixing with an inert gas such as nitrogen, and the preparation method is not particularly limited. The amount of the (D) cationic polymerization catalyst to be used is preferably 0.01 or more in total with respect to (A) trioxane.
001 to 0.02% by weight. (D) If the amount of the cationic polymerization catalyst is more than 0.02% by weight, the thermal stability of the resin is reduced. If the amount is less than 0.0001% by weight, the polymerization activity is remarkably reduced, which is not preferable.

In the production of the polyacetal resin of the present invention, (A) trioxane, (B) cyclic ether and / or cyclic formal, and (C) a low molecular weight acetal compound are used by using (D) a cationic polymerization catalyst. When performing bulk polymerization and continuous production of polyacetal resin, (C)
The mixture obtained by once mixing the low molecular weight acetal compound and the (D) cationic polymerization catalyst is added to and supplied to (A) a trioxane or a mixture of (A) trioxane and (B) a cyclic ether and / or cyclic formal. I do.
In mixing (C) the low molecular weight acetal compound and (D) the cationic polymerization catalyst, the mixing method is not limited at all.

As such a method, for example, a method of continuously joining and mixing in a pipe, a method of continuously joining,
Further, there may be mentioned a method of mixing with a static mixer, a method of supplying mixed components once mixed in a container equipped with a stirrer, and the like. In the mixing of the above components, the mixing temperature and the mixing time are not particularly limited. If specified, the mixing temperature is between -70 and 150C, preferably between -50 and 75C. The mixing time is 0.05 to
It is 10,000 seconds, preferably 0.1 to 2,000 seconds.

In the mixing of (C) the low molecular weight acetal compound and (D) the cationic polymerization catalyst, (C) the low molecular weight acetal compound may be used in its entirety, or may be used in its entirety. Some may be used for mixing with (D) the cationic polymerization catalyst and the remaining amount may be added to (A) trioxane and / or (B) cyclic ether and / or cyclic formal. The mixture of the (C) low molecular weight acetal compound and the (D) cationic polymerization catalyst mixed by the above method is liquefied (A) trioxane or (A)
A bulk polymerization is carried out by adding and supplying the mixture of the trioxane and the (B) cyclic ether and / or cyclic formal to obtain a polymer in the form of a solid powder. As a polymerization machine, 2
A kneader having a drive shaft and mixing means such as screws, paddles, disks, pins, and blades directly connected to the drive shaft.
A co-kneader type polymerization machine is exemplified. The polymerization temperature is preferably maintained at 65 to 135 ° C., and the residence time of the polymerization machine is preferably 0.2 to 30 minutes.

The deactivation after the polymerization is carried out by adding a basic compound, an aqueous solution thereof, or the like to a reaction product discharged from the polymerization machine after the polymerization reaction or a reaction product in the polymerization machine. Examples of the basic compound for neutralizing and deactivating the polymerization catalyst include ammonia; amines such as triethylamine, tributylamine, triethanolamine and tributanolamine; hydroxides of alkali metals or alkaline earth metals. , Carbonates and the like; other known catalyst deactivators are used.

After the polymerization method and the deactivation method, if necessary, washing, separation and recovery of unreacted monomers, drying, etc. are performed by a conventionally known method. Further, if necessary, such as decomposition removal of the unstable terminal, or sealing of the unstable terminal with a stable substance, a stabilization treatment by a known method,
Various necessary stabilizers are blended. Examples of the stabilizer used herein include one or more of a hindered phenol compound, a nitrogen-containing compound, an alkali or alkaline earth metal hydroxide, an inorganic salt, and a carboxylate. Can be mentioned. Further, as long as the present invention is not impaired, if necessary, general additives to the thermoplastic resin, for example, coloring agents such as dyes or pigments, lubricants, nucleating agents, release agents, antistatic agents, surfactants Agent, or
One or more kinds of organic polymer materials, inorganic or organic fibrous, powdery or plate-like fillers and the like can be added.

According to the method for producing a polyacetal resin of the present invention, polymerization can be carried out uniformly, and the fluctuation of the torque of the polymerization reactor is reduced. Can be obtained. In addition, the polyacetal resin obtained in the present invention is excellent in balance of mechanical properties, chemical resistance, slidability, etc., and also excellent in moldability, other than injection molded products,
It can be used in various fields such as extruded products and blow molded products, and is extremely useful.

[0023]

EXAMPLES Hereinafter, the present invention will be described specifically, but the present invention is not limited to these examples. In the present invention, in the case of a weight% of the substance A to trioxane,
It means that the weight ratio of substance A / trioxane is a% by weight / 100% by weight. (Example 1) A continuous mixing reactor using a barrel having a jacket through which a heat (cooling) medium passes and a cross section having a shape in which two circles partially overlap with each other and a rotary shaft with paddles is used. Was. While rotating the two rotating shafts with a paddle in the opposite direction at 150 rpm, one end is attached to one end.
Trioxane containing 3.3% by weight of 3-dioxane (vs. trioxane) was continuously fed. Subsequently, at the same time, methylal 0.1% by weight and boron trifluoride 0.002% by weight
(All with trioxane), and continuously mixed and mixed in the pipe (mixing temperature -5 ° C, mixing time 5 seconds),
While continuously adding and supplying the mixture into the polymerization machine,
Bulk polymerization was performed. The fluctuation of the rotating shaft torque of the polymerization machine
It was determined from the current value of the motor for driving the rotating shaft, and the fluctuation of the torque of the polymerization machine was evaluated by its standard deviation / average value and maximum value / average value. Table 1 shows the results.
The smaller these values are, the smaller the fluctuation of the polymerization machine torque is,
This shows that the production of polyacetal resin is stable.

Example 2 In the same manner as in Example 1, trioxane was continuously supplied using a continuous mixing reactor. Subsequently, at the same time, 0.1% by weight of methylal and 0.002% by weight of boron trifluoride (all with respect to trioxane) were continuously mixed and mixed in the pipe (mixing temperature −5 ° C.,
The mixing time was 5 seconds), and the mixture was continuously added to the polymerization machine. Bulk polymerization was carried out while continuously adding and feeding 3.3% by weight of 1,3-dioxolane (relative to trioxane) from another supply port into the polymerization machine. Subsequently, the fluctuation of the polymerization machine torque was evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 3 As in Example 1, a continuous mixing reactor was used to contain 3.3% by weight of 1,3-dioxolane and 0.03% by weight of methylal (all based on trioxane). Trioxane was fed continuously. Subsequently, at the same time, 0.07% by weight of methylal and 0.002% by weight of boron trifluoride (all based on trioxane)
After continuous merging and mixing in the pipe (mixing temperature -5
C., mixing time: 4 seconds), and the mixture was continuously added and fed into a polymerization machine to perform bulk polymerization. Subsequently, the fluctuation of the polymerization machine torque was evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 4 1,3-Dioxolane 3.3
Bulk polymerization was carried out in the same manner as in Example 1 except that 4.1% by weight of 1,4-butanediol formal (based on trioxane) was used instead of 1% by weight. Subsequently, the fluctuation of the polymerization machine torque was evaluated in the same manner as in Example 1. Table 1 shows the results.
Shown in

Example 5 Instead of boron trifluoride,
Bulk polymerization was carried out in the same manner as in Example 1 except that 0.006% by weight (based on trioxane) of boron trifluoride diethyl etherate was used. Subsequently, the fluctuation of the polymerization machine torque was evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 6 Instead of 0.1% by weight of methylal, oxymethylene di-n-butyl ether 0.2
Bulk polymerization was carried out in the same manner as in Example 1 except that the weight% (relative to trioxane) was used. Subsequently, the fluctuation of the polymerization machine torque was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Comparative Example 1) As in Example 1, a continuous mixing reactor was used, and at one end, 3.3% by weight of 1,3-dioxolane and 0.1% by weight of methylal (to trioxane) were added. The trioxane added was continuously supplied. Subsequently, simultaneously, boron trifluoride 0.002% by weight
Bulk polymerization was performed while continuously adding and supplying (to trioxane) to the polymerization machine. Subsequently, the fluctuation of the polymerization machine torque was evaluated in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 1,3-Dioxolane 3.3
Bulk polymerization was carried out in the same manner as in Comparative Example 1, except that 4.1% by weight of 1,4-butanediol formal (vs. trioxane) was used instead of 1% by weight. Subsequently, the fluctuation of the polymerization machine torque was evaluated in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 3 Instead of boron trifluoride,
Bulk polymerization was carried out in the same manner as in Comparative Example 1, except that boron trifluoride diethyl etherate was used in an amount of 0.006% by weight (based on trioxane). Subsequently, the fluctuation of the polymerization machine torque was evaluated in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 4 Oxymethylene di-n-butyl ether 0.2 was used instead of methylal 0.1% by weight.
Bulk polymerization was carried out in the same manner as in Comparative Example 1 except that the weight% (based on trioxane) was used. Subsequently, the fluctuation of the polymerization machine torque was evaluated in the same manner as in Example 1. Table 1 shows the results.

[0033]

According to the method for producing a polyacetal resin of the present invention, a polyacetal resin can be stably obtained industrially for a long period of time with little fluctuation in the torque of a polymerization machine.

[Table 1]

Claims (4)

[Claims] 1. A polyacetal resin is continuously produced by subjecting (A) trioxane, (B) a cyclic ether and / or cyclic formal, and (C) a low molecular weight acetal compound to bulk polymerization using a (D) cationic polymerization catalyst. In the method, the mixture obtained by mixing (C) the low molecular weight acetal compound and (D) the cationic polymerization catalyst once is converted into (A) trioxane or (A) trioxane and (B) a mixture of cyclic ether and / or cyclic formal. And a method for continuously producing a polyacetal resin by adding, supplying and polymerizing. (B) The cyclic ether and / or cyclic formal is ethylene oxide, 1,3-dioxolan,
The method for continuously producing a polyacetal resin according to claim 1, wherein the method is at least one selected from the group consisting of diethylene glycol formal and 1,4-butanediol formal. 3. The method for continuous production of a polyacetal resin according to claim 1, wherein the cationic polymerization catalyst (D) is at least one selected from the group consisting of boron trifluoride and a boron trifluoride coordination compound. 4. The method for continuously producing a polyacetal resin according to claim 1, wherein (C) the low molecular weight acetal compound is at least one selected from the group consisting of a chain transfer agent represented by the following general formula (1). . R ¹ —O — (— CH ₂ O—) n—R ² (1) (where R ¹ and R ² are alkyl groups having 1 to 20 carbon atoms,
Each may be the same or different, and n represents an integer of 1 to 20. )