JPS6053052B2 - Continuous polymerization method of phenols - Google Patents

Description

Detailed Description of the Invention The present invention relates to a continuous polymerization method for phenols, and more specifically, in the presence of a catalyst, a mixed solvent system consisting of a good solvent and a non-solvent for polyphenylene ether is used to polymerize oxygen-containing gas. In carrying out oxidative precipitation polymerization using a mixture of the general formula (I) and containing a phenol, a catalyst, and a solvent, the mixture is brought into countercurrent contact with oxygen or an oxygen-containing gas tower type or tubular reactor. The method is characterized in that preliminary polymerization is carried out in a tank-type reactor, and then precipitation polymerization is carried out in a tank-type reactor.

Polyphenylene ether is widely used as an engineering plastic with excellent heat resistance and mechanical properties, and blends with styrenic copolymers are particularly famous. Polyphenylene ether polymerization is a conventional polymer synthesis method, usually in an organic solvent system, using amine complexes such as copper, cobalt, manganese, alkoxides, imine complexes, etc., and blowing oxygen or oxygen-containing gas under vigorous stirring. This is carried out by an oxidative coupling reaction.

At this time, the reaction is thought to proceed as a type of equilibrium reaction called a quinol ether reaction. This reaction is difficult to control because it is a rapid reaction, and is not necessarily suitable for production by batch polymerization. On the other hand, polyphenylene ether is not necessarily as good as other polymers in terms of moldability. In JP-A No. 21798, the present inventors connected three complete mixing tanks in series, continuously added a mixed liquid consisting of monomer, catalyst, solvent, etc. to the first tank, and the first tank was used for homogeneous polymerization. We proposed a method in which precipitation polymerization is carried out in the second tank and thereafter.

The combination of a homogeneous polymerization tank and a precipitation polymerization tank is because the polymerization reaction is a quinol ether equilibrium reaction, so monomer is continuously added to the first tank, and the average degree of polymerization in this tank is difficult to increase. This is because it is difficult to complete the precipitation when the purpose is to obtain polyphenylene ether with a high degree of polymerization. The present inventors further improved this method,
The present invention was achieved by developing a method for producing polyphenylene ether with a uniform degree of polymerization in a shorter time using a simpler process. That is, this method cleverly takes advantage of the fact that this polymerization reaction proceeds through contact between oxygen gas and a catalyst, and that it proceeds through a quinol ether equilibrium reaction. In continuous polymerization using a complete mixing tank, monomer is constantly supplied to the first tank, so the molecular weight of the liquid discharged from this tank is lower than the molecular weight of batch polymerization at the same reaction time as the average residence time. , and the distribution is wide. stomach. Therefore, for example, if it is desired to complete the precipitation or to precipitate most of it in the second tank, it is necessary to set the average residence time of the first tank to be sufficiently long. However, when the reaction liquid and oxygen or oxygen-containing gas are brought into countercurrent contact as in the present invention, the gas-liquid contact area is large. Because it can be carried out quickly, and because the reaction liquid flows in one direction, there is little back mixing, the quinol ether equilibrium reaction can proceed toward the polymer production side, and the molecular weight can be rapidly increased in a short reaction time, allowing countercurrent flow. The molecular weight distribution at the outlet of the contact reactor is uniform, and the precipitation operation in the next tank reactor is easy, and problems such as scale adhesion can be avoided.
This will be explained in more detail below. The phenols that can be used in this invention have the following general formula (1).

(In the formula, R1, R2, R3, R4, R5 represent a hydrogen atom, a hydrocarbon group, a hydrocarbonoxy group, a halogen atom, a halogenated hydrocarbon group, an amino group, a substituted amino group, and X is a hydrogen atom or an alkali Represents a metal atom.

) Specific examples include o-cresol, 2,6-dimethylphenol, 2,6-diethylphenol, 2,4,
6-trimethylphenol, 2,3,6-trimethylphenol, 2,6-dimethyl-4-chlorophenol,
Examples include 2,6-diphenylphenol, 2-aminophenol, and others.

These may be used alone or in a mixture of two or more. All known catalysts can be used as catalysts, such as cuprous salts and mono-, secondary-, and tertiary amines, diamine complexes, polyamine complexes, cobalt and amines, diamine complexes, manganese and amines, diamine complexes, and these. Examples of combinations of alkali metal hydroxides, alkoxides, phenoxides, cobalt, manganese and salicylaldehyde alkylamine complexes, bissalicylaldehyde ethylenediimine complexes, and further alkali metal hydroxides, one,
Examples include secondary and tertiary amines, diamines, alkoxides, phenoxides, and other combinations.

Reaction solvents include toluene, benzene, xylene, chlorobenzene and other aromatic solvents, which are good solvents for polyphenylene ether, chloroform carbon tetrachloride, methylene chloride,
Examples include methyl chloroform, ethylene dichloride, other halogenated hydrocarbons, and non-solvents such as methanol, ethanol, propanol and other alcohols, dimethylformamide, dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, and the like.

These mixing ratios are appropriately selected depending on the molecular weight of the target polyphenylene ether, the precipitated particle size, etc. Usually, the above-mentioned phenols, catalyst, and solvent are mixed and supplied to the polymerization reactor as a homogeneous solution using a metering pump.
Each may be supplied singly or in combination.

When polyphenylene ether is obtained as precipitated particles in the reaction system, as in the present invention, the presence of a small amount of a surfactant in the system of 0.1 to 5% by weight based on the amount of monomers normally used can prevent the formation of scale. This ensures stable continuous operation for a long time.

Particularly, the effect is remarkable when prepolymerization is carried out in the countercurrent contact reactor of the present invention. After all, in a countercurrent contact reactor,
This is because there is always a large gas-liquid interface compared to the tank type, and scale tends to form in this area in many cases. Furthermore, when the countercurrent contact reactor of the present invention is used, the oxidative polymerization catalyst tends to become unstable because the contact area of gas and liquid is large.

For example, when polymerizing using a cuprous chloride-amine complex as a catalyst, non-negligible evaporation of the amine component is observed. On the other hand, when a chelate complex (for example, cobalt-bissalicylaldehyde ethylenediimine chelate, manganese-bissalicylaldehyde ethylenediimine chelate) is used as a catalyst, the above-mentioned problem does not arise. However, when catalysts in which amines or other volatile basic molecules are coordinated with these chelate complexes are used, similar evaporation is observed. It is desirable to add basic substances such as amines, diamines, amides, alkalis, alkoxides, and phenoxides. Generally, the presence of these basic substances significantly increases the stability of the catalyst. The feature of the present invention is that in continuous polymerization of polyphenylene ether, phenols,
The method involves prepolymerizing a mixed liquid consisting of a catalyst, a solvent, etc. and oxygen or an oxygen-containing gas by bringing them into countercurrent contact, and then precipitating polymerization in a tank reactor.

As a prepolymerizer for bringing the mixed liquid into countercurrent contact with oxygen or an oxygen-containing gas, a reaction tower such as a plate tower, a packed tower, a spray tower, or a leaking wall tower can be used. The reaction mixture is supplied from the upper part of the column. For example, tray columns using foam bell trays, uni-flux trays, cascade trays, perforated plate trays, etc., and packed columns using ring-shaped backing,
Use saddle type backing, McMahon packing, etc. The reaction solution after prepolymerization is continuously supplied to a tank-type reactor, and oxygen or oxygen-containing gas is blown into the reactor while stirring to precipitate polyphenylene ether while polymerizing it.
Although it depends on the solvent composition of the reaction solution, the [η] (chloroform at 25°C) of the polyphenylene ether discharged from the prepolymerization vessel is usually about 0.05 to 0.20, and the polyphenylene ether discharged from the tank reactor usually has a [η] of about 0.05 to 0.20. [η] (same as above) is about 0.2 to 0.7. Therefore, if the objective is to obtain polyphenylene ether with a higher intrinsic viscosity, or if the precipitated particles are separated and the monomer is added to the filtrate and recycled to the reaction system again, precipitation should be carried out at as high a rate as possible. If desired, it is preferable to combine one more tank reactor. The reaction temperature controls side reactions,
From the viewpoint of stability of continuous operation, the temperature should be set below the boiling point of the solvent, and it is usually carried out at a temperature of 20 to 80°C. In accordance with the most preferred embodiment of the present invention, the prepolymerization vessel is 30 to 60' C1, the first tank type reactor is 25 to 5 (generations),
The second tank reactor is set at a temperature of 10 to 30°C, but can be operated within the above temperature range. In addition, the average residence time in each reactor cannot be generalized because it can vary widely depending on the degree of polymerization of the target polyphenylene ether, the type of solvent used, and the composition ratio, but it is roughly shown below. The prepolymerization time in the prepolymerization vessel is 1 minute to 3 hours, particularly preferably 2 minutes to 1 hour, and the first tank type reactor is 1 minute to 5 hours, particularly preferably 1 to 2 hours. Two-tank reactor: 1 to 5 powders
The time is particularly preferably 1 to 3 hours. According to this invention, high quality polyphenylene ether can be obtained in a short time, and the process can be operated more stably, resulting in high productivity.

Examples will be described below.

Example 1 A jacketed glass tube with an inner diameter of 30 m was filled with 500 cc of stainless steel Dixon rings with three diameters, and the lower part was connected to a 1.5e jacketed glass tank reactor.

The tank reactor is equipped with an overflow pipe in the capacity 1e. A silicone rubber tube was attached to this overflow tube and squeezed with a pinch cock to continuously draw out the reaction solution. Each jacket has 40
C and 3C) C hot water was supplied.

The liquids used for the reaction are toluene 12' and methanol 6e1.
2,6-xylenol 2k9,N,N-ethylenebis(
Salicylidene iminate) Ethylenediamine complex of manganese was prepared by mixing ethylenediamine 1469. This liquid was supplied from the top of the prepolymerizer at a rate of 40 ml/min using a metering pump, and oxygen gas was supplied from the supply pipe attached to the tank reactor while vigorously stirring the tank reactor. Using a pinch cock connected to the overflow pipe of the tank reactor, the reaction solution is continuously drawn out at a rate of approximately 40 m1/min, and the solid and liquid are separated continuously using a centrifuge. After washing the solid portion with methanol, hydrochloric acid is removed. The mixture was washed with methanol and dried to obtain a white polyphenylene ether powder. The [η] of this polymer in chloroform at 25°C was 0.53.

Example 2 In Example 1, another tank reactor of the same type was connected in series, water at 20° C. was supplied to the jacket of this tank, and oxygen was passed through each tank for polymerization.

As a result, the conversion rate was 90% with respect to the amount of monomer charged [η
] (Same as above)=0.62 A white polyphenylene ether powder was obtained. Example 3 In Example 2, instead of using the ethylenediamine complex of N,N'-bis(salicylidene iminate) manganese and ethylenediamine 146y, cuprous chloride 2
A solution prepared by dissolving 2f in 1700 fI of pyridine was used.

As a result, a white polymer with [η]=0.43 was obtained with a yield of 86%. Example 4 In Example 2, Emulgen 903 (manufactured by Kao Atlas) 20y was added to the mixed solution and the same operation was performed.

As a result, in Example 2, some scale adhesion was observed on the stirring blade and gas-liquid interface of the first tank reactor, but almost no scale was observed in this example.

[η] (same as above) of the polymer obtained with a yield of 93% is 0.
It was 58. Example 5 Benzene 37.5k9, methanol 15.6k9, 2.
6-xylenol 8k9, N,N'-bis(salicylidene iminate) manganese ethylenediamine complex 374f
1 Ethylenediamine 590y1 Piperidine 80y1 Emulgen 903 (manufactured by Kao Atlas) 80y.
Example 2 was carried out with a feed rate of m1/min.

As a result, no scale was observed and stable operation was possible for a long period of time. The obtained polyphenylene ether has a yield of %,
[η] (same as above) was 0.73.

Claims (1)

[Claims] 1. In oxidation-precipitation polymerization of phenols in the presence of a catalyst in a mixed solvent system consisting of a good solvent and a non-solvent of polyphenylene ether, using an oxygen-containing gas, the following general formula (I ) is brought into countercurrent contact with an oxygen-containing gas in a column or tube reactor to prepolymerize it, and then precipitated and polymerized in a tank reactor. Continuous polymerization method for phenols. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1 to R_5 are hydrogen atoms, hydrocarbon groups, hydrocarbon oxy groups, halogen atoms, halogenated hydrocarbon groups,
It represents an amino group or a substituted amino group, and X represents a hydrogen atom or an alkali metal atom. )2 The continuous polymerization method for phenols according to claim 1, which uses a mixed solution containing phenols, a catalyst, a solvent, and a surfactant. 3 Claims that use a liquid mixture containing a basic substance selected from the group consisting of primary, secondary, tertiary amines, diamines, amides, alkalis, alkoxides, and phenoxides in addition to phenols, catalysts, and solvents. 1. Continuous polymerization method for phenols according to item 1.