JP2696944B2 - Continuous production method of oxymethylene copolymer - Google Patents

Description

The present invention relates to a method for producing a novel oxymethylene copolymer.

More specifically, the present invention relates to a method for producing a high-molecular-weight oxymethylene copolymer in a short time and in a high yield by bulk-polymerizing trioxane or the like using a boron trifluoride-based catalyst.

<Prior Art> A method of obtaining an oxymethylene copolymer by bulk polymerization of trioxane and a cyclic ether using a boron trifluoride-based catalyst is known, for example, from Japanese Patent Publication No. 36-14640. Since then, various improved methods have been proposed, but recently, a large number of bulk polymerization methods using a twin-screw reactor have been proposed. For example, JP-A-51-84890, JP-A-53-86794
JP-A-55-164214, JP-A-56-38313, JP-A-57-139113, JP-A-59-159812, JP-A-60-101108, etc. A method for producing an oxymethylene copolymer by a polymerization method has been proposed.

<Problems to be Solved by the Invention> The above-mentioned JP-A-51-84890, JP-A-53-86794, JP-A-55-164214, JP-A-56-38313, and JP-A-56-38313 In order to obtain a polymer having a high degree of polymerization in a high yield of 95% or more by the techniques disclosed in JP-A-57-139113, JP-A-59-159812, and JP-A-60-101108, The residence time is too short in a single-screw reactor in one stage, which is impossible, and a two-stage or multi-stage reactor is absolutely necessary.

Further, for example, even if the L / D of the reactor (L is the length of the reactor and D is the inner diameter thereof) is increased to increase the residence time, the reactants become liquid to slurry as the polymerization proceeds.
Because of a large change from a lump to a powder, in a two-shaft reactor with a large L / D, eccentricity of the rotating shaft occurs, making steady operation difficult.
Further, for example, in the above-mentioned Japanese Patent Application Laid-Open No. 59-159812, trioxane, cyclic ether and catalyst are premixed once and then supplied to a twin-screw reactor to shorten the residence time in the twin-screw reactor. Attempts to do so are disclosed. However, the mixture of the three naturally reacts and easily solidifies, so that the polymer easily accumulates in the pre-mixer and the supply port is easily clogged, so that steady operation is also difficult.

The inventors of the present invention have solved the problems of the prior art described above and have conducted intensive studies to obtain a high polymerization degree polymer in a single stage in a single-screw or multi-screw reactor in a short time. Reached.

<Means for Solving the Problems> That is, the present invention relates to the coordination of trioxane, a cyclic ether, boron trifluoride, boron trifluoride hydrate, and boron trifluoride with an organic compound containing an oxygen atom or a sulfur atom. Oxymethylene using an extruder-type reactor in which at least one polymerization catalyst selected from the group consisting of compounds is supplied from an inlet of a polymerization reactor to perform bulk polymerization, and the produced polymer is discharged from an outlet of the polymerization reactor. In a continuous production method of a copolymer, a polymerization reactor has two parallel stirring shafts, a plurality of paddles mounted on each shaft and a barrel close to the outer periphery of the paddle, and the shafts are simultaneously moved in the same direction. Using a self-cleaning type twin-screw mixer that rotates with a slight clearance between the paddle surface and barrel inner surface of each other when rotating, the catalyst is Before entering the polymerization reactor, the catalyst is activated by merging with a cyclic ether and mixing in a pipe in 0.1 to 3 minutes, and then supplied to the polymerization reactor so as to come in contact with trioxane. This is a method for continuously producing a polymer.

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

(Wherein, 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 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,
m shows the integer of 0-3. Alternatively, X is - (CH ₂₎ p
—O—CH ₂ — or —O—CH ₂ — (CH ₂ ) p—O—CH ₂ —, where m = 1 and p is 1-3
Is an integer. Among the cyclic ethers represented by the above general formula (I), particularly preferred compounds are ethylene oxide, propylene oxide, 1,3-thioxolan, 1,3-dioxane, 1,3
-Dioxepane, 1,3,5-trioxepane, 1,3,6-trioxocan, epichlorohydrin and the like.

The copolymerization amount of the cyclic ether of the present invention is in the range of 0.1 to 10 mol%, particularly preferably 0.2 to 6 mol%, based on trioxane.
If the amount is more than mol%, the polymerization time is undesirably long.

The polymerization catalyst used in the present invention is boron trifluoride, at least one selected from the group consisting of boron trifluoride hydrate and a coordination compound of boron trifluoride and an organic compound containing an oxygen atom or a sulfur atom. Compound, gaseous,
Used as a liquid or as a solution in a suitable organic solvent. Examples of the organic compound having an oxygen or sulfur atom that forms a coordination compound with boron trifluoride include alcohol, ether, phenol, sulfide, and the like. Among these catalysts, coordination compounds of boron trifluoride are particularly preferable, and especially boron trifluoride / diethyl ether complex, boron trifluoride / di (n-butyl) ether complex,
Boron trifluoride-phenol complexes are preferred.

In addition, benzene, toluene,
Aromatic hydrocarbons such as xylene, aliphatic hydrocarbons such as n-hexane, n-heptane and cyclohexane, alcohols such as methanol, ethanol and isopropanol, chloroform, dichloromethane, 1,2-dichloroethane, carbon tetrachloride And ketones such as acetone and methyl ethyl ketone.

The amount of the polymerization catalyst to be added is 0.1 to 1 mol of trioxane.
The range is preferably from 0.1 to 0.1 mol, particularly preferably 0.0
The range is from 0001 to 0.01 mol.

The activation of the catalyst of the present invention by the cyclic ether is achieved by allowing a certain period of time to elapse after the two are combined. In the present invention, the simplest in-pipe mixing is used.

It is performed in a time of 0.1 to 3 minutes. The temperature may be within a range in which both the catalyst and the cyclic ether are in a liquid state, and usually 0 to 70 ° C is preferably used. If the time is less than 0.1 minute, the activation of the catalyst is insufficient and the effect of improving the polymerization time is small, and if the time exceeds 3 minutes, the polymerization of the cyclic ether itself proceeds, and the viscosity is high, so that supply to the polymerization machine becomes difficult. Or copolymerized in a block shape, which is not preferable from the viewpoint of physical properties.

The term "activation time" as used herein means the total residence time of the mixed liquid including the supply pipe and the supply nozzle to the inside of the mixer and further to the polymerization reactor at the junction of the catalyst and the cyclic ether.

In the case of the bulk polymerization used in the present invention, a self-cleaning type mixer having a strong stirring ability and capable of controlling the reaction temperature is particularly preferably used because rapid solidification and heat generation occur during the polymerization in the case of the bulk polymerization. Is done.

The L / D that can maintain the small clearance between the paddle and barrel inside the polymerization reactor or between the paddles is 20
The following is usually selected in the range of 6 to 15. The residence time in this polymerization reactor is usually 0.5 to 30 minutes, preferably 1 to 1
0 minutes, more preferably 1 to 5 minutes.

The polymerization temperature is preferably in the range of 50 to 140C, particularly preferably in the range of 65 to 125C. If the temperature is lower than 50 ° C., the polymerization rate is slow because trioxane is solid, and if the temperature is 125 ° C. or higher, the depolymerization reaction becomes predominant and a high molecular weight polymer cannot be obtained, which is not preferable.

In addition, the polymerization reactor can be supplied with suitable molecular weight regulators and other additives.

Oxymethylene copolymer produced according to the present invention,
It is put to practical use after stabilization by blocking or removing unstable terminals. In this case, a generally known method is employed as a stabilization method.

Next, an example of an embodiment of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, the catalyst supplied from the catalyst supply pipe 3 joins with the cyclic ether supplied from the cyclic ether supply pipe 2 before entering the supply port 4 and is activated by mixing in the pipe. The mixture of the activated catalyst and the cyclic ether enters the polymerization machine 5 together with the trioxane supplied from the trioxane supply pipe 1. The polymerization machine 5 is a two-shaft self-cleaning type mixer having a stirring shaft 9, a plurality of plate-like paddles 7, and a temperature adjusting jacket 8. The cross-sectional shape of the paddle 7 has a convex lens shape as shown in FIG. The lower part of the supply port of the polymerization machine 5 is constituted by a usual screw 10. The polymerized polymer is discharged from the discharge port 6.

<Action> In the present invention, the catalyst is sufficiently activated in advance by a cyclic ether. By supplying the activated catalyst to the polymerization reactor, the polymerization time can be greatly reduced, and a high yield and high molecular weight polymer of 95% or more can be obtained in a short time.

<Examples> 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.

Relative viscosity of oxymethylene copolymer ηr; 0.5 g of oxymethylene copolymer was dissolved in 100 ml of p-chlorophenol containing 2% α-pinene, and measured at 60 ° C. using an Ostwald viscometer.

Polymerization yield of oxymethylene copolymer; 100 g of oxymethylene copolymer discharged from the polymerization machine in 3 ml of benzene
After stirring at room temperature for 0 minutes, the polymer was filtered off and dried in vacuo. The polymer weight after drying was measured, and the polymerization yield (%) was determined.

Thermal decomposition rate of oxymethylene copolymer Kx; Kx means the decomposition rate when left for a certain period of time at x ° C. About 10 mg of a sample is left at x ° C in an air atmosphere using a thermobalance device, and the following formula is used. I asked for it.

Kx = (W ₀ −W ₁ ) / W ₀ × 100% W ₀ ; weight of sample before heating W ₁ ; weight of sample after heating The thermal balance apparatus used was a thermal analyzer 1090/1091 manufactured by DuPont.

Mechanical properties of oxymethylene copolymer; Injection molding of tensile test specimens and Izod impact test specimens by setting the cylinder temperature to 200 ° C, the mold temperature to 60 ° C, and the molding cycle to 50 seconds using an injection molding machine with an injection capacity of 5 oz. did. Using these molded products, the tensile strength and Izod impact value were each measured using ASTM D-
638, measured according to D-256.

Example 1 A self-cleaning type twin-screw mixer having a paddle of a convex lens type in cross section as shown in FIG. 2 was used as a polymerization reactor, and trioxane 433 g / h was used in a flow as shown in FIG.
Was supplied. 1.95 g / h of a benzene solution containing 3.70% by weight of boron trifluoride / diethyl etherate as a catalyst and 14.1 g / h of 1,3-dioxolane as a cyclic ether at room temperature,
The mixture was supplied at 30 ° C. by mixing in a pipe.

The inner diameter of the reactor was 25 mm, and the L / D was 10. The paddle has 22 flat / paddles and helical paddles combined, and the lower part of the supply port is a normal screw. The reactor jacket was adjusted to 90 ° C. with warm water.
The stirring shaft was set at 175 rpm with the same rotation. At this time, the average residence time was 5 minutes, and a white fine powder polymer was obtained.

Table 1 shows the test results obtained by adjusting the length of the supply pipe after the catalyst and 1,3-dioxolan were combined and changing the activation time.

Example 2 Polymerization was carried out in the same manner as in Example 1 except that the supply pipe portion after the catalyst and 1,3-dioxolan were combined was heated with warm water.
The catalyst activation time was 3 minutes. The results are shown in Table 2.

Example 3 In the same apparatus as in Example 1, trioxane 860 g / h, catalyst 3.90
g / h and 38.9 g / h of 1,3-dioxepane were fed, and the catalyst was activated at 30 ° C. for 1 minute to carry out polymerization in the same manner as in Example 1. At this time, the average residence time was 3 minutes, and ηr of the obtained polymer was
2.00, yield was 96%.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that the catalyst and 1,3-dioxolane were not combined and supplied to the reactor through a separate supply pipe. The resulting polymer is still in a slurry state and the conversion is
It was as low as 50-60%.

As is clear from Examples 1 to 3 and Comparative Example 1, by pre-activating the catalyst, the polymerization time can be greatly reduced, and a high polymerization degree and a high yield can be obtained with one polymerization machine.

Based on 100 parts by weight of the polymer obtained in Example 3, 0.27 parts by weight of bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, pentaerythrityl-tetrakis [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate] 0.50 parts by weight, calcium hydroxide 0.
10 parts by weight and 0.10 parts by weight of dicyandiamide were added, and the mixture was melt-kneaded at 210 ° C. for 10 minutes in a mixer having two roller blades. After crushing the obtained polymer and performing injection molding, the mechanical properties and heat resistance stability of the molded product were measured,
All exhibited good values. The measured values are shown below.

Tensile strength; 64 MPa Tensile breaking elongation; 62% Izod impact value: 66 J / m (1/2 "notch) Thermal decomposition rate K ₂₄₀ (60 min); 3.0% Example 4 A reactor similar to that of Example 1 was used as a reactor. D = 100mm, L /
20 kg / h of trioxane was supplied using a two-shaft self-cleaning mixer with D = 10. 0.10 kg / h of a benzene solution containing 3.70% by weight of boron trifluoride / diethyl etherate as a catalyst and 0.64 kg / h of 1,3-dioxolane in 30
C., and the mixture was supplied for 1 minute in the piping.

The reactor is equipped with 36 flat-paddles and helical paddles, each with a convex lens cross section, and a shaft. The lower part of the supply port is a normal screw. The reactor jacket was adjusted to 60 ° C. with warm water. The stirring shaft was set at 60 rpm with the same rotation. The average residence time at this time was 4 minutes. 19.6 kg / h of powdery polymer was obtained from the discharge part.
The ηr of the polymer was 2.03 and the yield was 98%.

Based on 100 parts by weight of the polymer thus obtained, 0.27 parts by weight of bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate and triethylene glycol-bis [3- (3-t- Butyl-5-methyl-hydroxyphenyl) propionate] 0.50 parts by weight, calcium hydroxide
0.10 parts by weight of melamine and 0.10 parts by weight of melamine were added, and the mixture was continuously supplied to a conventional twin-screw extruder equipped with a vent, and was melt-stabilized at 230 ° C. and 50 torr. The stabilized polymer was immediately pelletized and obtained as pellets at 18.0 kg / h.

Injection molding was performed using this polymer, and the mechanical properties and heat stability of the molded product were measured. The results are shown below.

Tensile strength: 64 MPa Tensile breaking elongation: 63% Izod impact value: 66 J / m (1/2 ″ notch) Thermal decomposition rate K ₂₄₀ (60 min); 2.9%

<Effects of the Invention> By using the production method of the present invention in the production process of polyacetal copolymer used for a wide range of applications such as mechanical mechanism parts and electric / electronic parts, the production process can be greatly reduced, and the productivity can be improved. I can do it.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view of a polymerization machine for carrying out the present invention, and FIG. 2 is a partial cross-sectional view of a convex lens type paddle in the polymerization reactor. DESCRIPTION OF SYMBOLS 1 ... Trioxane supply pipe, 2 ... Cyclic ether supply pipe, 3 ... Catalyst supply pipe, 4 ... Supply port, 5 ... Polymerization reactor, 6 ... Discharge port, 7, 7 '... Paddle, 8 ... jacket, 9, 9 '... stirring shaft, 10 ... screw.

Claims (1)

(57) [Claims] At least one member selected from the group consisting of trioxane, a cyclic ether, boron trifluoride, boron trifluoride hydrate, and a coordination compound of boron trifluoride and an organic compound containing an oxygen atom or a sulfur atom. In the continuous production method of an oxymethylene copolymer using an extruder-type reactor in which a polymerization catalyst is supplied from an inlet of a polymerization reactor to perform bulk polymerization and the produced polymer is discharged from an outlet of the polymerization reactor. Having two parallel stirring shafts as a polymerization reactor, a plurality of paddles mounted on each shaft and a barrel close to the outer periphery of the paddle, and simultaneously rotating the shafts in the same direction, the paddle surfaces of each other. And using a self-cleaning twin-screw mixer that rotates with a slight clearance between the barrel and the inner surface of the barrel. Performs activation of the catalyst by pipe mixed with 0.1 to 3 minutes flowed, continuous process for preparing polyoxymethylene copolymers, which comprises subsequently fed to the polymerization reactor in contact with trioxane.