JPH10330444A - Production of polyacetal resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a polyacetal copolymer having high quality in high yield by smoothly transferring a slurry part and suppressing the elevation of the inside temperature of a reactor attributable to polymerization heat generation. SOLUTION: This is a method for producing a polyacetal resin by the continuous block polymerization of trioxane with a cyclic ether which is carried out by using a self cleaning-type continuous stirring mixer consisting of two or more parallel axes which rotate in the direction same to or different from each other, plural paddles attached to each of the axes, a body which locates closely to the periphery of the paddles, a raw material inlet located near one end of the axes and an outlet located near the other end of the axes for discharging the reaction product. In this process, the continuous stirring mixer is placed in such a state where the axes are tilted by 1-10 deg. to the horizontal direction by lifting the raw material inlet side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyacetal capable of obtaining a high-quality polymer in a high yield by smoothly feeding a slurry-like portion and suppressing a temperature rise in a reactor due to heat generated by polymerization. The present invention relates to a method for producing a resin.

[0002]

2. Description of the Related Art In bulk polymerization of trioxane, a polymer is rapidly precipitated with a rise in temperature due to polymerization heat generated in a reactor, and a polymerization product changes from a slurry to a paste.
Eventually solidifies. Some proposals have been made to remove the heat of polymerization and to carry out a polymerization reaction involving a phase change without causing problems such as deterioration due to heat generation and torque-out due to solidification.

For example, in the manufacturing method described in Japanese Patent Publication No. Hei 5-8725, the tip of the paddle of one shaft is always in contact with the inner surface of the body or the paddle of the other shaft while keeping a slight gap. It has been proposed to raise the rear outlet of the reactor so that the reaction is carried out in a state in which the reactor is inclined at an angle of 1 to 10 ° with respect to the horizontal. However, in this method, the feed amount of the reaction mixture, particularly at the stage from the slurry state to the paste state, becomes unstable, and the residence time varies, so that the heat removal of some reaction mixtures becomes insufficient, A high-quality polyacetal resin that is preferable as a product cannot be obtained.

In the production method described in Japanese Patent Publication No. 62-13973, the reaction mixture is fixed to the same stirring shaft so that the feed of the reaction mixture gradually decreases from the raw material supply port of the reactor toward the reaction product discharge port. It has been proposed to arrange the adjacent paddles continuously or stepwise at an angle or to use paddles of a different kind of feeding force. However, even in this method, the heat of the reaction mixture, particularly in the stage from a slurry state to a paste state, is insufficient, and the retention time of some reaction products varies, so that heat removal is not possible. It is not sufficient to obtain a high quality polyacetal resin which is preferable as a product.

In the manufacturing method described in Japanese Patent Publication No. 47-629, the self-cleaning function is insufficient due to a rapid phase change, so that the screw member is clogged and an overload state is caused. To avoid this, it has been proposed to reduce the filling rate of the polymerization reaction mixture and increase the pulverization efficiency by providing a gap between the screw member and the casing. However, in this method, the polymerization mixture adheres to the gap between the screw member and the casing, so that heat removal becomes insufficient, and a high-quality polyacetal resin cannot be obtained.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-quality polymer by smoothly feeding a slurry-like portion in the production of a polyacetal resin and suppressing the temperature rise in the reactor due to heat generated by polymerization. An object of the present invention is to provide a method for obtaining a high yield.

[0007]

That is, the present invention provides (1) two or more parallel shafts which rotate in the same direction or different directions, a plurality of paddles attached to each shaft, and a body close to the outer periphery of the paddle. Using a self-cleaning type continuous stirring mixer having a raw material supply port near one end of the shaft and a discharge port near the other end of the shaft to discharge a reaction product, trioxane and cyclic ether are continuously bulk-polymerized. Is a method of producing a polyacetal resin by raising the raw material supply port side of the continuous stirring mixer, making a gradient such that the axis of the continuous stirring mixer has an inclination angle of 1 to 10 ° with respect to the horizontal. A method for producing a polyacetal copolymer, comprising installing a continuous stirring mixer; (2) raising the raw material supply port side so that the axis of the continuous stirring mixer is 1 to 1 with respect to the horizontal.
The method according to the above (1), wherein a continuous stirring mixer is installed with a gradient so as to have a tilt angle of 0 °, and trioxane, a cyclic ether and a polymerization catalyst are supplied from a raw material supply port to cause a reaction. (3) The method for producing a polyacetal resin described in (3), wherein a plurality of self-cleaning type continuous stirring mixers are used as the reactor, and the reaction mixture discharged from the discharge port of the preceding continuous stirring mixer is subjected to the next continuous stirring. The mixture is connected so as to be supplied from the raw material supply port, and the raw material supply port side of the foremost continuous stirring mixer is lifted, and the axis of the continuous stirring mixer is inclined so as to have an inclination angle of 1 to 10 ° with respect to the horizontal. A continuous stirring mixer is installed, and trioxane, a cyclic ether and a polymerization catalyst are supplied from the raw material supply port to cause a reaction, and the polymer is supplied from the discharge port of the last stage continuous stirring mixer. (1) The method for producing a polyacetal resin according to the above (1) or (2), wherein a mixture obtained by previously mixing a cyclic ether and a polymerization catalyst is added to trioxane, followed by a polymerization reaction. (5) The method for producing a polyacetal resin according to any one of (1) to (3) above, wherein (5) the continuous stirring mixer is configured such that the tip of one paddle has a slight clearance with the inner surface of the body or the paddle of the other shaft. (1) to (1) to (4), which are continuous stirring mixers having a function of mutually scraping the reaction mixture by rotating while maintaining
(4) The method for producing a polyacetal resin according to any one of (4) and (6) a continuous stirring mixer in which the tip of one paddle is a paddle on the inner surface of the body or the other shaft, and a clearance of 2% or less of the diameter of the circumcircle of the paddle. The method for producing a polyacetal resin according to any one of the above (1) to (5), wherein the rotation is performed while maintaining the rotation.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A continuous stirring mixer used in the present invention has two or more parallel shafts rotating in the same direction or different directions, a plurality of paddles attached to each shaft, and close to the outer periphery of the paddle. Body, a self-cleaning type continuous stirring mixer having a raw material supply port near one end of the shaft and a discharge port near the other end of the shaft, and usually, the tip of one paddle has a body inner surface or By rotating the paddle with the other shaft while maintaining a small clearance, the function of scraping the reaction mixture from each other, ie, self-
A continuous stirring mixer having a cleaning function can be used.

In the present invention, the continuous stirring mixer used as a reactor is characterized in that the raw material supply port side is lifted up and installed with a gradient so as to be inclined at a specific range of angle. The inclination angle is set so that the axis of the continuous stirring mixer is inclined at 1 to 10 ° with respect to the horizontal plane, preferably at 2 to 5 °. As a result, during the continuous operation of the reactor, the reaction stage in which a remarkable phase change occurs, in particular, the feed amount from a slurry state to a paste state is stabilized, and the amount of abnormally retained polymer is significantly reduced, so that the polymerization operation is very good. And a high quality polymer can be obtained.

In the self-cleaning type continuous stirring mixer, in order to obtain a good self-cleaning effect, the clearance between the paddle tip and the inner surface of the drum is preferably 2% or less, more preferably, the diameter of the circumcircle of the paddle. 1% or less.

The continuous stirring mixer used in the present invention is usually provided with a jacket for controlling the reaction temperature, and the temperature of the cooling water or hot water flowing through the jacket is determined in consideration of the balance between the heat removal and the polymerization reaction rate. Usually 0 to 95
° C, preferably 1 to 70 ° C, particularly preferably 2 to 70 ° C.
50 ° C.

[0012] The ratio of the length (L) of the barrel of the continuous stirring mixer to the inner diameter (D) of the barrel, ie, L / D, is usually considered in consideration of machining accuracy and fluctuation of clearance due to shaft deflection and operation stability. 20 or less, preferably 3 to 15.

The shape of the paddle of the continuous stirring mixer used in the present invention is a convex lens type, an elliptical type, or a pseudo-polygon inscribed in an imaginary circle at each apex angle. A helical type that is symmetrically twisted and whose side surface is rotationally symmetric with respect to the stirring axis can also be used. That is, the helical type whose side is twisted to push the contents to the discharge port by the rotation of the stirring shaft has a larger feeding effect than the normal flat type, and the helical type twisted in the opposite direction has a larger reverse feeding effect. Is shown. The tip of the paddle may have a circumferential surface, may be flat, may be sharp, or may be provided with a sharp scraper.

In the present invention, a polyacetal resin is produced by continuously bulk-polymerizing trioxane and a cyclic ether, which are polymerization raw materials, using a self-cleaning type continuous stirring mixer as described above. In this method, as the reactor, one continuous stirring mixer is used, and trioxane and cyclic ether are supplied from a raw material supply port of the continuous stirring mixer, and polymerized from a discharge port of the continuous stirring mixer. Or a plurality of reactors including the continuous stirring mixer, the reaction mixture discharged from the discharge port of the preceding continuous stirring mixer may be supplied from the raw material supply port of the next continuous stirring mixture. At least one of the continuous stirring mixers is installed with a gradient as described above, and the raw material of the foremost reactor is used. Trioxane from the sheet inlet, and supplies the cyclic ether may be obtained polyacetal resin from the discharge port of the reactor of the last stage.

When a plurality of reactors are used, it is preferable to install a continuous stirring mixer at an inclined position in a portion where a reaction in which a significant phase change occurs occurs. Specifically, trioxane and a cyclic ether are supplied. It is preferable that the continuous stirring mixer is installed at an inclination at the foremost stage where the reaction is started. There is no particular limitation on the reactor at a later stage, but it can be installed substantially horizontally.

For example, a continuous stirring mixer is installed at the forefront,
Trioxane and cyclic ether may be supplied from the raw material supply port of the continuous stirring mixer, and a polymerized polyacetal resin may be obtained from the discharge port of the last reactor. In this case, there is no particular limitation on the reactor after the continuous stirring mixer installed with a gradient as long as the reactor can finally produce a polyacetal resin, and the same type of continuous stirring as the first stage is used. It may or may not be a mixer. As the most preferred embodiment, as a reactor, two or three continuous stirring mixers are connected, and a continuous stirring mixer in which the raw material supply port side is lifted and installed as described above is provided as a first stage, and trioxane, In this method, a cyclic ether is supplied, and a polyacetal resin is obtained from the discharge port of the last reactor.

The outlet of the reactor used in the present invention is
It is preferable that a taper whose diameter increases toward the subsequent stage is provided on the wall of the discharge port in order to prevent the reaction mixture from adhering. In the case where the reactors are connected to each other, it is preferable that a connecting pipe connecting the reactor discharge port and a reactor material supply port at a later stage is also provided with a taper whose diameter increases toward the latter stage.

The cyclic ether used in the present invention includes:
Formula (I)

Embedded image The compound shown by these is mentioned. (Where Y1-
Y4 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen-substituted alkyl group having 1 to 6 carbon atoms, which may be the same or different. X represents a methylene or oxymethylene group, which may be substituted with an alkyl group or a halogen-substituted alkyl group, and m represents an integer of 0 to 3. Or X is _{- (CH 2) p-O} -CH 2 - or _{-O-CH 2 - (CH 2} ) p-O-CH 2 - is a even better, in this case a m = 1, p = Integer of 1-3. Particularly preferred compounds among the cyclic ethers represented by the above general formula include ethylene oxide, propylene oxide, 1,3-dioxolan, 1,3-dioxane,
3-dioxepane, 1,3,5-trioxepane, 1,
3,6-trioxocan, epichlorohydrin and the like can be mentioned.

The copolymerization amount of the cyclic ether of the present invention is preferably from 0.1 to 10 mol%, particularly preferably from 0.2 to 6 mol%, based on trioxane.

In the present invention, a polymerization catalyst can be used for the polymerization of trioxane and cyclic ether.
Examples of such polymerization catalysts include metal halide compounds such as boron trifluoride, metal halide complexes such as boron trifluoride hydrate and coordination compounds of boron trifluoride and an organic compound containing an oxygen atom or a sulfur atom. , Inorganic acids such as heteropoly acids, or also organic acids and the like,
Used as a gaseous, liquid or solution of a suitable organic solvent. Among these catalysts, a coordination compound with boron trifluoride is preferable, and as an organic compound having an oxygen or sulfur atom forming a coordination compound with boron trifluoride,
Alcohols, ethers, phenols, sulfides and the like are mentioned, and among them, boron trifluoride / diethyl ether complex, boron trifluoride / di (n-butyl) ether complex and boron trifluoride / phenol complex are preferable.

Examples of the solvent for the polymerization catalyst include aromatic hydrocarbons such as benzene, toluene and xylene;
Aliphatic hydrocarbons such as hexane, n-heptane and cyclohexane, alcohols such as methanol, ethanol and isopropanol, halogenated hydrocarbons such as chloroform, dichloromethane, 1,2-dichloroethane and carbon tetrachloride, acetone and methyl ethyl ketone Ketones such as are used.

The amount of the polymerization catalyst to be added is preferably from 0.000005 to 0.1 mol, particularly preferably from 0.00001 to 0.01 mol, per 1 mol of trioxane.

Such a polymerization catalyst can be charged into a raw material supply port of a continuous stirring mixer together with trioxane and a cyclic ether to cause a polymerization reaction.
It is preferable to add the compound to trioxane or add it to the raw material supply port together with trioxane to cause a polymerization reaction.

The polymerization temperature is from 50 to 140 ° C., preferably from 65 to 140 ° C.
25 ° C. is preferred.

The polyacetal resin (coarse polymer) thus polymerized is usually discharged as a powder from the discharge port of the reactor, and such a coarse polymer is usually used after the polymerization catalyst is deactivated and the unstable terminal ends. Stabilized by blocking or removing, and put to practical use. In this case, a generally known method is employed as a method for deactivating and stabilizing the catalyst.

As a terminator for the boron trifluoride-based catalyst particularly preferably used in the present invention, an amine compound, a tertiary phosphine compound and a hindered amine compound are used. Of these, tertiary phosphine compounds and hindered amine compounds are extremely advantageous in terms of process because there is no need to remove the deactivated catalyst. In particular, hindered amine compounds give polymers with excellent thermal stability,
It is more preferably used.

It is also possible to supply an appropriate polymerization degree regulator and other additives to the polymerization reaction.

[0028]

Next, the present invention will be described with reference to Examples and Comparative Examples. The physical properties and the like shown in Examples and Comparative Examples were measured as follows.

MI value: A pellet obtained by stabilizing a powdery crude polymer obtained in the polymerization stage by a known method is dried in a hot air oven at 80 ° C. for 3 hours, and then subjected to ASTM D12.
The measurement was performed at a temperature of 190 ° C. and a load of 2160 g according to No.

Polymerization yield: 100 g of the powdery crude polymer discharged from the latter-stage polymerization machine was mixed with 500 g of benzene in 3 ml.
After stirring for 0 minutes at room temperature, the polymer was filtered off and dried under vacuum. The weight of the crude polymer after drying was measured to determine the polymerization yield (%).

Thermal decomposition rate K: K means the decomposition rate when left at 240 ° C. for a certain period of time, and about 10 mg of a sample is left at 240 ° C. in an air atmosphere using a thermobalance device to obtain the following formula: I asked for it.

K = (Wo−W60) / Wo × 100 (%) Wo: Weight of sample before heating W60: Weight of sample after heating for 60 minutes The thermobalance device is TG / DTA20 manufactured by Seiko Denshi.
Using 0, measurement was performed at 240 ° C. for 60 minutes.

Formaldehyde content in pellets:
3 g of a sample was charged into a mini autoclave made of SUS316 and having a volume of 5 ml, and the autoclave was replaced with nitrogen gas.
Heat treatment was performed at 30 ° C. for 30 minutes, and gas analysis was performed. Gas analysis was performed by gas chromatography using a GC-
12. The heat conduction type detector (TCD) and the column packing were TSG-1 manufactured by Wako Pure Chemical Industries, Ltd., and the column temperature was 150 ° C.

Measurement of the motor current value of the polymerization reactor: In the state where the polymerization reaction is continuously performed, the current value of 6
The average motor current value I for 0 minute and the standard deviation δ were determined.

Example 1 The self-cleaning type twin-screw reaction mixer shown in FIG. 1 was used as a first-stage reactor and a second-stage reactor. 3
Was set to have an inclination angle θ, and the latter reactor was set to an inclination angle of 0 degree.

A benzene solution containing 30 kg / h of trioxane melted at 75 ° C. at a raw material supply port and 2.4 wt% of boron trifluoride / diethyl etherate as a catalyst was added at 0.1 wt.
15 kg / h and 1,3-dioxolane as cyclic ether were fed at 1.1 kg / h. FIG. 1 is a partially cut-away side view of a self-cleaning twin-screw reaction mixer used as a pre-stage and post-stage reactor. The reactor is a twin-screw self-cleaning continuous mixer having a stirring shaft 1, a plurality of paddles 2, and a jacket 3 for temperature control.
The trioxane, the cyclic ether and the catalyst are supplied from a supply port 4, and the polymerized polymer is discharged from a discharge port 5. Reference numeral 6 denotes a screw. Further, 0.024 kg / hour of methylal was supplied as a molecular weight regulator.

The inner diameter and L / D of the reactor were 100 mm for the first stage reactor, L / D = 7.2, and 200 m for the second stage reactor.
m, L / D = 5. The paddle has a convex lens-shaped cross section as shown in FIG.
m and 20 mm were used. FIG. 2 is a cross-sectional view of a convex paddle having a self-cleaning function.
They were arranged in combinations shifted by 90 degrees and 90 degrees. The paddles of the latter reactor were arranged so as to have a small feeding effect. In particular, a paddle having a thickness of 10 mm was incorporated in the reverse direction in the second half to enhance the return effect. The stirring shaft was rotated in the same direction and the front stage was set at 75 rpm and the rear stage was set at 30 rpm. Cooling water at 15 ° C. was used in both the first and second stages.

From the discharge port, a white powder coarse polymer was 29.4.
kg / hr. At this time, the polymerization yield was 94%.

As a catalyst deactivator, bis (1,2,2,6,6) was added to 100 parts by weight of the obtained white powdery polymer.
0.18 parts by weight of -pentamethyl-4-piperidinyl) sebacate (Sankyo "Sanol" LS765) at 9% by weight
After the addition as a benzene solution, triethylene glycol bis {3- (3-t-butyl-5-methyl-4) is further added.
-Hydroxyphenyl) propionate (Ciba-Geigy "Irganox" 245) 0.5 part by weight, calcium stearate 0.1 part by weight, benzoguanamine 0.1
Parts by weight and continuously fed to a normal twin screw extruder, 23
The unstable terminal was melt-stabilized at 0 ° C. and 10 mmHg, discharged into water, and cut to obtain a pellet-like polyacetal copolymer. The MI value of the obtained pellet was 9.8 g / 10 minutes. The thermal decomposition rate K of the pellets was 2.9%, and the formaldehyde content was 25 p.
pm. The average value of the motor current during the polymerization reaction was 17
A, the standard deviation was 0.21 A, and the polymerization reaction was stably carried out. Table 1 shows the results.

[0040]

[Table 1] Example 2 Under the same conditions as in Example 1, the inclination angle θ of the pre-reactor was set to 5
The polymerization reaction was performed as a degree. The polymerization yield of the obtained crude polymer was 92%. After subjecting this crude polymer to the same treatment as in Example 1, the MI
The value was 9.5 g / 10 min, and the thermal decomposition rate was 2.4%. The average value of the motor current during the polymerization reaction was 16 A, the standard deviation was 0.15 A, and the polymerization reaction was stably carried out.

Example 3 Under the same conditions as in Example 1, the inclination angle θ of the pre-reactor was set to 8
The polymerization reaction was performed as a degree. The polymerization yield of the obtained crude polymer was 91%. After subjecting this crude polymer to the same treatment as in Example 1, the MI
The value was 8.9 g / 10 min, the formaldehyde content was 24 ppm, and the thermal decomposition rate was 2.5%. The average value of the motor current during the polymerization reaction was 16 A, and the standard deviation was 0.1.
2A, and the polymerization reaction was stably performed.

Comparative Example 1 Under the same conditions as in Example 1, the inclination angle θ of the pre-stage reactor was set to 0.
The polymerization reaction was performed as a degree. The polymerization yield of the obtained crude polymer was 95%. After subjecting this crude polymer to the same treatment as in Example 1, the MI
The value was 11.5 g / 10 min, the thermal decomposition rate was formaldehyde content of 120 ppm, and the thermal decomposition rate was 10.3.
%, And a high quality polymer was not obtained. The average value of the motor current during polymerization was 23 A, and the standard deviation was 0.93.
A, and the variation of the current value was large.

Comparative Example 2 Under the same conditions as in Example 1, the inclination angle θ of the pre-reactor was set to 1
The polymerization reaction was carried out at 5 degrees. The polymerization yield of the obtained crude polymer was 83%, which was significantly lower than that of Example 1. After subjecting this crude polymer to the same treatment as in Example 1, the MI value of the obtained polymer was 10.9 g / 1.
0 minutes, the formaldehyde content is 108 ppm,
The thermal decomposition rate was 9.8%, and a high quality polymer was not obtained. The average value of the motor current during the polymerization reaction was 14
A, the standard deviation was 0.12A.

[0044]

According to the present invention, by raising the raw material inlet side of the reaction mixer, the longitudinal axis of the reactor is 1 to the horizontal.
Obtaining a high quality polymer in high yield by controlling the temperature in the reactor due to the heat generated by the polymerization by smoothly feeding the slurry-like part with a gradient so as to have a tilt angle of 10 °. Can be.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view of a reactor used in the present invention in an example.

FIG. 2 is a cross-sectional view of a convex paddle having a self-cleaning function used in an example.

[Explanation of symbols]

 1: stirring shaft 2: paddle 3: temperature control jacket 4: supply port 5: discharge port 6: screw θ: tilt angle

Claims (6)

[Claims] 1. Two or more parallel shafts rotating in the same direction or different directions, a plurality of paddles attached to each shaft,
Using a self-cleaning type continuous stirring mixer having a body near the paddle periphery, a raw material supply port near one end of the shaft and a discharge port near the other end of the shaft to discharge a reaction product, trioxane and cyclic ether are mixed. A method for producing a polyacetal resin by continuous bulk polymerization, wherein the raw material supply port side of the continuous stirring mixer is lifted, and the axis of the continuous stirring mixer has an inclination angle of 1 to 10 ° with respect to the horizontal. A method for producing a polyacetal copolymer, wherein a continuous stirring mixer is provided with a gradient as described above. 2. A continuous stirring mixer is installed by raising the raw material supply port side so that the axis of the continuous stirring mixer has an inclination angle of 1 to 10 ° with respect to the horizontal. 2. The method for producing a polyacetal resin according to claim 1, wherein the reaction is carried out by further supplying trioxane, the cyclic ether and the polymerization catalyst. 3. A continuous stirring mixer of a plurality of self-cleaning types is used as a reactor, and a reaction mixture discharged from a discharge port of a preceding continuous stirring mixer is supplied from a raw material supply port of a next continuous stirring mixture. And the raw material supply port side of the first-stage continuous stirring mixer is lifted, and the continuous stirring mixer is inclined such that the axis of the continuous stirring mixer has an inclination angle of 1 to 10 ° with respect to the horizontal. And supplying trioxane, a cyclic ether and a polymerization catalyst from the raw material supply port to cause a reaction, and obtaining a polyacetal resin from the discharge port of the last continuous stirring mixer. 3. The method for producing a polyacetal resin according to 2. 4. The process for producing a polyacetal resin according to claim 1, wherein a mixture obtained by previously mixing a cyclic ether and a polymerization catalyst is added to trioxane, followed by a polymerization reaction. 5. The continuous stirring mixer has a function of scraping off the reaction mixture from each other by rotating the tip of one paddle while keeping a small clearance with the inner surface of the barrel or the paddle of the other shaft. The method for producing a polyacetal resin according to any one of claims 1 to 4, wherein the method is a continuous stirring mixer. 6. The continuous stirring mixer according to claim 1, wherein the tip of one paddle rotates while keeping a clearance of not more than 2% of the diameter of the circumcircle of the paddle with the paddle of the inner surface of the body or the other shaft. 6. The method for producing a polyacetal resin according to any one of items 5 to 5.