JP2525460B2 - Method for producing polyacetal copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a novel method for producing a polyacetal copolymer.

More specifically, for example, it is a biaxially rotating twin-barreled cylindrical reactor which is parallel to each other and has a paddle having a plurality of convex lens-type or elliptical cross-sections using a boron trifluoride-based catalyst. The present invention relates to a method for producing a high-molecular-weight polyacetal copolymer by introducing trioxane in a solid phase state and continuously performing bulk polymerization with the continuous stirring and mixing machine.

<Prior Art> Using the above reactor, bulk polymerization of trioxane or the like to produce a polyacetal copolymer is disclosed in Japanese Patent Application Laid-Open
55-164212, JP-A-56-38312, JP-A-58
-32621, JP-A-62-96515 and the like.

<Problems to be Solved by the Invention> JP-A-55-164212, JP-A-56-38312,
In the technique of introducing molten trioxane into the reaction system disclosed in JP-A-58-32621 and JP-A-62-96515, the heat generated during the polymerization is insufficiently removed, so that the reaction The temperature rises too much to accelerate the depolymerization reaction, and it is difficult to obtain a polymer excellent in color tone, degree of polymerization, and mechanical properties.

Further, in the case of using molten trioxane in the prior art, there is a drawback that there is a melting step on equipment, and a loss is large in terms of time and energy.

Further, the molten trioxane supply pipe may be clogged due to solidification of trioxane or generation of oligomers, which may hinder the polymerization reaction.

Therefore, when producing a polyacetal copolymer by bulk polymerization of trioxane or the like, how to suppress heat generation and establish an industrially advantageous production method has been one of the major problems.

Therefore, the present inventors have found the present invention as a result of diligently studying a method for producing a polyacetal copolymer having a uniform and high degree of polymerization, which solves the above-mentioned problems of the prior art.

<Means for Solving the Problems> That is, the present invention is a method for producing a polyacetal copolymer by reacting trioxane with another cyclic ether compound in the presence of a catalyst, and as a polymerization reactor, a plurality of convex lenses or Equipped with an elliptical plate-shaped paddle, using a parallel biaxially rotating twin barrel continuous stirring mixer with self-cleaning action on the paddle surface and the cylinder inner wall, and solid trioxane in the reaction system. The present invention provides a method for producing a polyacetal copolymer, which is supplied in a state.

In the present invention, the polymerization reaction apparatus used is a so-called highly self-cleaning apparatus having a convex lens type paddle on the plate, which preferably has a sharp tip, and this type of apparatus includes scale adhesion and accompanying deflection of a stirring shaft and There is no problem of eccentricity. Further, it has an inner cavity provided with a raw material supply port and a reaction product discharge port at a distant position, and is provided with a temperature control jacket on the outer periphery of this barrel,
It is preferable that the hollow cylinder has an agitation shaft located parallel to the longitudinal direction of the cylinder, and the agitation shaft has a plurality of plate paddles fixed so as to be in contact with each other. As a preferable reaction method, the paddle on the plate has a convex lens type cross section in the direction perpendicular to the stirring axis direction, and the convex lens type cross section is sharp at both ends in the major axis direction and symmetrical with respect to a plane including the major axis. Using a continuous stirring mixer having a surface shape as a reactor, solid trioxane, a copolymerization component, a catalyst are continuously supplied from the supply port of the reactor, and the raw material mixture is moved to the discharge port by the rotation of the paddle. While carrying out the polymerization reaction.

Further, in the present invention, the copolymerization ratio of the cyclic ether is preferably 0.1 to 10 mol% with respect to trioxane,
It is particularly preferably in the range of 0.2 to 6 mol% and 0.1 mol%
If it is less than 10% by weight, thermal stability is low, and if it exceeds 10% by mole, mechanical properties are deteriorated, which is not preferable.

The cyclic ether used in the present invention means a compound represented by the following general formula (I).

However, in the formula, Y _{1 to} Y ₄ represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen-substituted alkyl group having 1 to 6 carbon atoms, and they 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-(C
_{H 2) P -O-CH 2} - or _{-O-CH 2 - (CH 2} ) P -O-C
It may be H ₂ −, in which case m = 1 and P is an integer from 1 to 3.

Among the cyclic ethers represented by the general formula (I), particularly preferable compounds are ethylene oxide, propylene oxide, 1,3-dioxolane, 1,3-dioxane, 1,
3-dioxepane, 1,3,5-trioxepane, 1,3,6-trioxocane, epichlorohydrin and the like can be mentioned.
Further, these copolymerization components may be mixed with the catalyst in advance, or the catalyst and the copolymerization component may be added separately.

The polymerization catalyst in the present invention is one or more compounds selected from the group consisting of boron trifluoride, boron trifluoride hydrate and a coordination compound of boron trifluoride and an organic compound containing an oxygen atom or a sulfur atom. It is preferably used in the form of a gas, a liquid or a suitable organic solvent.

As the solvent for the polymerization catalyst in the present invention, benzene,
Aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as n-hexane, n-heptane and cyclohexane, alcohols such as methanol and ethanol,
Halogenated hydrocarbons such as chloroform, dichloromethane and 1,2-dichloroethane, ketones such as acetone and methyl ethyl ketone are preferably used.

The addition amount of the polymerization catalyst was 0.
A range of 000005 to 0.1 mol is preferable, and 0.0 is particularly preferable.
It is in the range of 0001 to 0.01 mol. If it is less than 0.000005 mol, the polymerization reaction will be extremely slow, and if it exceeds 0.1 mol, the molecular weight will be decreased, which is not preferable.

In carrying out the method of the present invention, the temperature of the polymerization reaction is preferably 0 to 140 ° C, particularly preferably 20 to 100 ° C, further preferably 30 to 90 ° C. If the temperature is 0 ° C. or lower, the polymerization reaction is extremely slow, and if the temperature is 140 ° C. or higher, the produced polymer is thermally decomposed and it is difficult to obtain a high molecular weight polymer, which is not preferable.

The polyacetal copolymer produced by the present invention,
Since it has an unstable OH terminal group, it is thermally unstable, and after being stabilized in the stabilization step, it is put to practical use. In this case, the method for stabilizing the polyacetal copolymer includes a method of acetylating the terminal, a method of thermally decomposing in a basic solution, and a method of melt-stabilizing in the presence of a basic substance such as metal hydroxide. Generally known methods can be adopted.

In addition, the polyacetal copolymer of the present invention includes the known triethylene glycol bis [3- (3-t-butyl-
4-hydroxy-5-methyl-phenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-
t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-
An antioxidant such as di-t-butyl-4-hydroxyphenyl) propionate, a thermal decomposition inhibitor such as melamine and dicyandiamide may be optionally contained.

<Example> Next, the present invention will be described with reference to Examples and Comparative Examples.

In this example, a biaxial reactor as shown in FIG. 1 was used, that is, a co-rotating type reactor,
It is marketed under the product name of KRC Kneader S1 type (Kurimoto Iron Works). The diameter D of the paddle 4 was 25 mm, and the ratio of the trough length of the body 2 to the diameter of the paddle was L / D = 10.2. In the 4D region from directly below the supply port 3 to the discharge port 5, the tip is shifted by 45 ° or 90 ° in the same direction as the rotation direction of the stirring shaft 1, a feed helical paddle, and the next 5D region is rotated in the reverse direction. Flat and helical paddles were used alternately while shifting 45 ° or 90 ° each. For the last 1.2D area, a helical paddle was used, which was sequentially shifted in the opposite direction by 45 °. In the 4D area from directly below the supply port to the discharge port, feed angles 45 ° and 90 °
2 degrees, and reverse feed angles of 45 degrees and 90 degrees in the 5D area.
A total of 4 different paddle patterns were used. Table 1 shows the combinations. The temperature of the polymerization reactor was controlled by pouring hot water through the jacket, and the reaction system was measured by installing a thermocouple at 4D immediately below the feed port.

The obtained polymer was evaluated as follows.

(1) 0.1 g of Ca (OH) ₂ and pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] with respect to a crude polymer having a melt index (MI) of 100 g. To 0.5
g, bis (1,2,2,6,6-pentamethyl-4-piperidine)
Add 2 ml of 0.26 ml / of benzene solution of sebacate, and use a 100cc Labo Plastomill mixer from Toyo Seiki Seisakusho.
After the polymer was melt-stabilized at 10 ℃ for 15 minutes,
MI was measured.

MI measurement was carried out according to ASTM D1238 at a load of 2,160 g and a temperature of 190 ° C.

(2) A press sheet having a color tone of 1 mm was prepared, and the yellowness (YZ) was measured by a color machine manufactured by Suga Test Instruments Co., Ltd.

(3) Mechanical properties Using an injection molding machine with an injection capacity of 5 ounces, the cylinder temperature is 230 ° C, the mold temperature is 60 ° C, and the molding cycle is 50.
The tensile test piece, the Izod impact test piece, and the bending test piece were injection-molded by setting to seconds. Tensile properties were measured according to the ASTM D-638 method using the tensile test pieces obtained by the above injection molding. Also, impact strength is ASTMD-256 method, bending strength is ASTMD-
Each was measured according to the −790 method.

(5) Polymer Melting Point (Tm) Using a differential scanning calorimeter, the melting point (Tm) of the polymer was measured by raising the temperature at a rate of 10 ° C./min in a nitrogen atmosphere.

Examples 1 to 4 and Comparative Examples 1 and 2 433 g / h of solid trioxane in an A type twin-screw reactor.
Supplied with r. Also, a solution of 1,3-dioxolane, which is a copolymerization component, at 13.0 ml / hr and boron trifluoride / diethylate 0.158 ml / using benzene as a solvent was premixed at 2.2 ml / hr, and this was 15.2 ml / hr. Was fed at the rate of. The rotation speed is 100 rpm, each MI at reaction temperatures 30, 50, 70, and 90 ° C., the internal temperature at 4D from immediately below the supply port, and the measurement results by a color machine are shown in Table 2 as Examples 1 to 4.

For comparison, Table 2 shows the results of experiments in which molten trioxane at 70 and 90 ° C. was introduced and the reaction temperatures were 70 and 90 ° C., as Comparative Examples 1 and 2.

From the results shown in Table 2, it is understood that when the trioxane is introduced in the solid phase, the temperature rise due to heat generation is low, and a white polymer having a high degree of polymerization and excellent mechanical properties is obtained.
Further, it can be seen that the polymerization reaction is proceeding even below the melting point (64 ° C.) of trioxane.

Examples 5-7, Comparative Examples 3-5 Changing the paddle pattern type under the conditions of Example 3,
MI measurement and color machine measurement were performed. The results are shown in Table 3.

In addition, Table 3 shows, for comparison, the measurement results in the case where molten trioxane in the liquid phase was introduced into the reaction system.

From the results shown in Table 3, it can be seen that the polymer produced by the present invention has a high degree of polymerization, excellent mechanical properties and low yellowness in any of the paddle patterns.

Examples 8, 9 and Comparative Examples 6, 7 1,3-dioxolane was replaced by 1,3-dioxolane as a copolymerization component.
Examples of using dioxepane or ethylene oxide are shown in Table 4. Other conditions are the same as those in the third embodiment. Table 4 also shows the results of using molten trioxane at 70 ° C.

From the results shown in Table 4, even when other copolymerization components were used, the temperature rise due to heat generation was lower when solid phase trioxane was introduced,
It can be seen that a white polymer having a high degree of polymerization and excellent mechanical properties can be obtained.

Example 10 and Comparative Example 8 Table 5 shows the results of separately adding 1,3-dioxolane and the catalyst solution to solid trioxane as a raw material without premixing. The other conditions are the same as in Example 3. The results when molten trioxane at 70 ° C. is used as a comparative example are also shown in Table 5.

From the results shown in Table 5, compared with Example 3 in which the catalyst solution and 1,3-dioxolane were mixed in advance, Example 10 had a lower degree of polymerization, but the polymerization degree was higher than that in the case of using molten trioxane. It can be seen that a white polymer having an excellent degree of polymerization and mechanical properties was obtained.

Examples 11 and 12, Comparative Examples 9 and 10 Table 6 shows the results when the feed rate of solid trioxane was changed. Other conditions are the same as those in the third embodiment.
In addition, as a comparative example, the results of supplying molten trioxane at 70 ° C. at the same rate are also shown.

From the results shown in Table 6, even when the trioxane feed rate was increased, it was found that the solid phase trioxane feed did not cause a temperature rise due to heat generation and a white polymer having a high degree of polymerization and excellent mechanical properties was obtained.

Example 13 and Comparative Example 11 Table 7 shows the results when boron trifluoride / dibutyl etherate was used as the catalyst instead of boron trifluoride / diethyl etherate. Other conditions are the same as those in the third embodiment. In addition, as a comparative example, the experimental results of introducing molten trioxane at 70 ° C. are also shown.

From the results shown in Table 7, it can be seen that even when trifluoroboron dibutyl etherate is used as a catalyst, the solid polymer trioxane is supplied to obtain a white polymer having a high degree of polymerization and excellent mechanical properties.

Examples 14 and 15 and Comparative Examples 12 and 13 Table 8 shows the results of using hexane or toluene instead of benzene as the solvent. Other conditions are the same as those in the third embodiment. Further, as a comparative example, the experimental results of introducing molten trioxane are shown.

From the results shown in Table 8, it can be seen that even when the solvent is changed, a white polymer having a higher degree of polymerization and excellent mechanical properties is obtained when the solid phase trioxane is introduced.

Examples 16 and 17 Table 9 shows the results when methylal was used as a molecular weight regulator. Experimental conditions were the same as in Example 3, and methylal was further added to trioxane at concentrations of 240 and 330 ppm.

From the results shown in Table 9, it can be seen that when solid phase trioxane is used, a polyacetal copolymer of high viscosity grade to high fluidity grade can be produced by using a molecular weight modifier.

<Effects of the Invention> By using the production method of the present invention, trioxane can be supplied to a polymerization reactor in a crystalline state without being melted, and a high degree of polymerization can be obtained in a short time. A polyacetal copolymer can be obtained.

[Brief description of drawings]

1A and 1B are a partial cross-sectional plan view and a side view schematically showing a reactor used in the present invention, FIG. 2 is a partial cross-sectional view showing the shape of a pat, and FIGS. 3A and 3B are flat. It is a schematic diagram which shows a type paddle and a helical type paddle. 1 ... Stirring shaft 2 ... Cylinder 3 ... Supply port 4 ... Paddle 5 ... Discharge port

Claims (4)

(57) [Claims] 1. A method for producing a polyacetal copolymer by reacting trioxane with another cyclic ether compound in the presence of a catalyst, comprising a plurality of convex lenses or elliptical plate paddles as a polymerization reactor, and a paddle. A polyacetal characterized by using two parallel twin-spindle twin cylinder type continuous stirring mixers having self-cleaning action on the surface and the inner wall of a cylinder, and supplying trioxane in a solid state to a reaction system. Method for producing copolymer. 2. The method for producing a polyacetal copolymer according to claim 1, wherein the reaction temperature is in the range of 30 to 90 ° C. 3. The copolymerization ratio of the cyclic ether compound is 0.1 to 1.
The method for producing a polyacetal copolymer according to claim 1, wherein the content is in the range of 0 mol%. 4. The heavy catalyst is selected from the group consisting of boron trifluoride, boron trifluoride hydrate and a coordination compound of boron trifluoride with an organic compound containing an oxygen atom or a sulfur atom. The method for producing a polyacetal copolymer according to claim 1.