JPH07126387A - Production of polyether sulfone - Google Patents

Abstract

PURPOSE:To obtain a polyether sulfone having good heat stability. CONSTITUTION:This process for producing a polyether sulfone by polycondensing a dihalogenodiphenyl sulfone with a dihydric phenol compound in the presence of an alkali metal compound in an N,N-dimethylacetamide solvent, comprises using the N,N-dimethylacetamide as that recovered after the production of a polyether sulfone and purified to a tetramethylammonium chloride concentration of 50ppm or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyether sulfone having good heat stability.

[0002]

2. Description of the Related Art Polyether sulfone is
In an organic polar solvent, in the presence of an alkali metal compound, a polycondensation reaction of a dihalogenodiphenylsulfone compound and a dihydric phenol compound, or an alkali metal di-salt of a dihydric phenol is previously synthesized, and a dihalogenodiphenyl compound It is known that it can be obtained by a polycondensation reaction with (JP-B-42-7799, JP-B-45-21318, JP-A-48).
-19700).

Particularly, a method using N, N-dimethylacetamide as a solvent is described in, for example, ACS Polym.Prep., 14 (1), 36.
5 (1973), Japanese Patent Publication No. 5-408, etc. Generally, a method of improving thermal stability by adding an alkylating agent such as chloromethane as a terminal terminating agent after the polycondensation reaction is known, but when N, N-dimethylacetamide is recovered and reused. However, there is a problem that the thermal stability of the produced polyether sulfone is deteriorated.

[0004]

[Technical Means for Solving the Problems] The present inventors have found that after polycondensation reaction, tetramethylammonium chloride is present in the recovered N, N-dimethylacetamide solvent, and the recovered N, N-dimethylacetamide is recovered. It was clarified that this is one of the causes of the decrease in thermal stability of the produced polyether sulfone produced by reuse, and the concentration of tetramethylammonium chloride in the N, N-dimethylacetamide solvent was adjusted to 50 pp.
It was clarified that the thermal stability of the produced polyether sulfone was significantly improved by making the m or less.

In the present invention, in the presence of an alkali metal compound,
In a method for producing a polyether sulfone by polycondensing a dihalogenodiphenyl sulfone compound and a dihydric phenol compound in a N, N-dimethylacetamide solvent, N, N-
Dimethylacetamide was recovered after the production of polyethersulfone and the concentration of tetramethylammonium chloride was
The present invention relates to a method for producing polyether sulfone, which comprises using N, N-dimethylacetamide in an amount of 50 ppm or less.

The alkali metal compound used in the polycondensation reaction of the present invention is an alkali metal carbonate, an alkali metal hydroxide, an alkali metal hydride, or
Examples thereof include alkali metal alkoxides. Particularly, sodium carbonate and potassium carbonate are preferable.

The alkali metal compound is added before the polycondensation reaction.
It is also possible to use one which has been previously heat-treated in an inert gas such as nitrogen gas at 60 to 500 ° C. under normal pressure or reduced pressure for 1 minute or more, or one which has been dispersed in N, N-dimethylacetamide.

The dihalogenodiphenyl compound used in the present invention is a dihalogenodiphenyl compound having a sulfone group, for example, dihalogenodiphenyl sulfone such as 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone. Sulfones, 1,4-bis (4-chlorophenylsulfonyl) benzene, 1,4-bis (4-fluorophenylsulfonyl) benzene and other bis (halogenophenylsulfonyl) benzenes, 4,4'-bis (4- And bis (halogenophenylsulfonyl) biphenyls such as chlorophenylsulfonyl) biphenyl and 4,4′-bis (4-fluorophenylsulfonyl) biphenyl. In particular, 4,4'-dichlorodiphenyl sulfone, 4,4'-
Dihalogenodiphenyl sulfones such as difluorodiphenyl sulfone are preferred. Two or more kinds of the above dihalogenodiphenyl compounds can be mixed and used.

Examples of the dihydric phenol compound include hydroquinone, catechol, resorcin, 4,4'-biphenol, 2,2-bis (4-hydroxyphenyl) propane,
Bis (4-hydroxyphenyl) alkanes such as 2,2-bis (4-hydroxyphenyl) methane, dihydroxydiphenylsulfones such as 4,4′-dihydroxydiphenylsulfone, dihydroxydiphenylethers, hydroxydiphenylcycloalkanes, or At least one of the hydrogens on the benzene ring is substituted with a lower alkyl group such as a methyl group, an ethyl group or a propyl group, a lower alkoxy group such as a methoxy group or an ethoxy group, or a halogen such as chlorine, bromine or fluorine. There are some. In particular, hydroquinone, 4,4'-biphenol, 2,2-bis (4-hydroxyphenyl) propane, 4,
4'-Dihydroxydiphenyl sulfone is preferred. Two or more kinds of the above dihydric phenol compounds can be mixed and used.

The dihydric phenol compound is preferably used in a substantially equimolar amount with the dihalogenodiphenyl sulfone compound. In order to control the molecular weight of the polyaryl ether to be produced, the dihydric phenol compound may be used in an equimolar amount to a slight excess amount or an excessive amount amount. For this purpose, small amounts of monohalogenodiphenyl compounds or monohydric phenol compounds can be added to the polymerization solution.

In the present invention, the reaction temperature for polycondensation is usually
It is performed at 145 ° C or higher, preferably 150 ° C or higher. Water produced as a by-product during the reaction can be distilled out of the system with an inert gas stream or with an azeotropic dehydrating agent to produce a high molecular weight polyether sulfone. Examples of azeotropic dehydrating agents include benzene, toluene, xylene, and aromatic halogen compounds.

As a method of terminating the polymer, for example, chloromethane is usually added to the reaction solution at the end of the polycondensation in an amount of 90 to 1
Examples include a method of adding by blowing at 50 ° C. and a method of adding tetramethylammonium chloride in the presence of an alkali.

In the above production method, a polymer having a desired molecular weight is obtained as a reaction solution of an organic polar solvent.
The inorganic solid such as the alkali metal compound or the alkali metal halide remaining in the reaction solution can be separated by filtering or centrifuging the reaction solution. After the inorganic solid contained in the reaction solution is separated by filtration or centrifugation, or by adding the poor solvent to the reaction solution or the reaction solution to the poor solvent without separating the inorganic solid, the polyamine -Tersulphone can be separated as a precipitated solid.

Examples of the poor solvent for polyethersulfone include alcohols such as methanol, ethanol, isopropanol and butanol, nitriles such as acetonitrile, water and the like. Water is preferably used. Further, two or more kinds of the above compounds can be mixed and used. Further, the poor solvent may contain a good solvent for the polymer such as the above-mentioned polymerization reaction solvent, within the range where the polymer can be precipitated.

The precipitated solid is washed with a poor solvent and then dried, whereby a powder of polyethersulfone can be obtained.

The reduced viscosity of the polyethersulfone is usually 0.20 or more, preferably 0.25 or more.

In the present invention, as a method of recovering N, N-dimethylacetamide, the polymer is precipitated from the polymerization solution by stirring with the above poor solvent. Examples include a method in which the precipitated polymer is separated, then obtained as a mixed solution of N, N-dimethylacetamide and a poor solvent, and then separated and recovered by distillation or the like.

In the present invention, the concentration of tetramethylammonium chloride in N, N-dimethylacetamide is 50 pp.
It is necessary to be m or less, and preferably 10 ppm or less. When the concentration of tetramethylammonium chloride in N, N-dimethylacetamide exceeds 50 ppm, the thermal stability of the produced polyethersulfone decreases, as can be seen from the results of Comparative Examples described later.

There is no particular limitation on the method for reducing the concentration of tetramethylammonium chloride in N, N-dimethylacetamide to 50 ppm or less. The method of passing it through a column packed with the adsorbent is mentioned. A usual ion exchange resin can be used as the adsorbent.

[0020]

Industrial Applicability According to the method of the present invention, a polyethersulfone having excellent thermal stability can be produced in the method for producing a polyethersulfone using recovered N, N-dimethylacetamide.

[0021]

EXAMPLES Examples of the present invention will be described below. The reduced viscosity η _{SP / C} in the examples and comparative examples is represented by the following equation. η _{SP / C} = (tt ₀ ) / t ₀ / c where t is the transit time (sec) between the marked lines of the polymer solution in the viscometer, and t ₀ is the transit time between the marked lines of the pure solvent in the viscometer. (Sec), c represents the concentration of the polymer solution (g / 100 ml solvent). The viscosity was measured at 30 ° C. using an N-methyl-2-pyrrolidone solvent at a polymer solution concentration of 0.5 g / 100 ml.

The concentration of tetramethylammonium chloride in N, N-dimethylacetamide or the polymerization reaction solution was determined by the following method. N, N-dimethylacetamide containing tetramethylammonium chloride About 100 to 1
A sample of 20 g, or about 5-10 g of a polymerization solution containing tetramethylammonium chloride, was diluted with about 100 g of N, N-dimethylacetamide without tetramethylammonium chloride, and about 4,4'-biphenol was added to about 0.
After adding 7 g and about 1.25 g of potassium carbonate and heating at 160 ° C. for 90 minutes, the monomethoxy and dimethoxybiphenol compounds present in the reaction solution were quantified by gas chromatography. The concentration of tetramethylammonium chloride was determined in consideration of the N, N-dimethylacetamide dilution ratio after calculating the amount of tetramethylammonium chloride present in the sample by the following formula. (Amount of tetramethylammonium chloride present) = (Amount of monomethoxybiphenol present) + 2 × (Amount of dimethoxybiphenol present)

The thermal stability of polyether sulfone was evaluated by the following melt thermal stability test. That is, the internal volume
Using a 60 ml Brabender kneader, rotor speed 60
Kneading was carried out for 1 hour under the conditions of rpm, temperature of 340 ° C., and amount of polymer of 58 g, and the minimum torque value lowered by the melting of the polymer at the initial stage of kneading and the torque value after 1 hour of kneading were obtained. Since the torque value has a range during measurement, the average value of the minimum value and the maximum value was adopted as the torque value. The torque ratio was calculated according to the following formula. Torque ratio = (torque value after 1 hour) / (minimum torque value at the beginning of kneading) The smaller this torque ratio, the better the thermal stability of polyethersulfone.

Example 1 300 L of N, N-dimethylacetamide, 20 L of toluene as an azeotropic dehydration solvent, 4,4'-dichlorodiphenyl sulfone 7
3.3kg, hydroquinone 13.7kg, 4,4'-biphenol
Using 23.2 kg and 38 kg of potassium carbonate, stir at about 165 ° C for 8 hours in a nitrogen atmosphere to obtain a polymer concentration of about 23% by weight.
A polymerization solution of was obtained. After completion of the reaction, methyl chloride was blown into the polymerization solution to carry out a polymer end treatment operation. The polymerization solution was filtered under a nitrogen pressure of 1.5 kg / cm ² to obtain a polymerization solution in which inorganic substances were separated. The obtained polymerization solution contained 280 ppm of tetramethylammonium chloride.

300 L of the polymerization solution was poured into 1800 L of water, and the polymer was precipitated with vigorous stirring. After filtering and separating with a centrifuge, a polymer powder and a separation liquid (mixed liquid of N, N-dimethylacetamide and water) were obtained. 500 g of polymer powder in water
After washing twice with 3000 mL, dry at 90 ° C and reduce the reduced viscosity to 0.5.
A polyether sulfone powder of 5 was obtained. When a melt heat stability test was conducted using 58 g of this polyethersulfone powder, the initial kneading torque value was 90 Kgf · cm, and the torque ratio was 1.5.

The separated liquid is dehydrated under reduced pressure and then purified to obtain water content.
0.05wt%, tetramethylammonium chloride 30ppm
10 L of N, N-dimethylacetamide containing was recovered. Recovery
N, N-dimethylacetamide 300mL, azeotropic dehydration solvent toluene 200mL, 4,4'-dichlorodiphenyl sulfone
733g, hydroquinone 137g, 4,4'-biphenol 23
Using 2 g and potassium carbonate (380 g), the mixture was stirred under a nitrogen atmosphere at about 165 ° C. for 8 hours to obtain a polymerization solution having a polymer concentration of about 24% by weight. After completion of the reaction, methyl chloride was blown into the polymerization solution to carry out a polymer end treatment operation. The polymerization solution was filtered under a nitrogen pressure of 1.5 kg / cm ² to obtain a polymerization solution in which inorganic substances were separated.

200 mL of the polymerization solution was poured into 1200 mL of water, and the polymer was precipitated with vigorous stirring. Filtered by centrifuge,
After separation, a polymer powder was obtained. Polymer powder 500g
Was washed twice with 3000 mL of water and dried at 90 ° C to reduce the reduced viscosity.
A 0.55 powder of polyethersulfone was obtained. When a melt heat stability test was conducted using 58 g of this polyethersulfone powder, the initial kneading torque value was 95 Kgf · cm, and the torque ratio was 1.4.

Example 2 Example 2 was repeated except that 10 L of N, N-dimethylacetamide containing 0.05 wt% of water and 22 ppm of tetramethylammonium chloride was used, and the reduced viscosity was 0.5.
A polyether sulfone powder of 3 was obtained. When a melt heat stability test of this polyether sulfone was conducted, the kneading initial torque value was 92 Kgf · cm, and the torque ratio was 1.5.

Comparative Example 1 The same procedure as in Example 1 was repeated except that 10 L of N, N-dimethylacetamide containing 0.05 wt% of water and 100 ppm of tetramethylammonium chloride was used, and the reduced viscosity was 0.5.
A powder of polyethersulfone of 4 was obtained. When a melt heat stability test of this polyether sulfone was conducted, the initial kneading torque value was 89 Kgf · cm and the torque ratio was 1.8.

Comparative Example 2 The procedure of Example 1 was repeated except that 10 L of N, N-dimethylacetamide containing 0.07 wt% of water and 320 ppm of tetramethylammonium chloride was used, and the reduced viscosity was 0.5.
A polyether sulfone powder of 5 was obtained. When a melt heat stability test of this polyether sulfone was conducted, the kneading initial torque value was 92 Kgf · cm, and the torque ratio was 1.8.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kuniaki Kitamura 8-1 Goi Minamikaigan, Ichihara City, Chiba Ube Industries Ltd. Chiba Research Institute

Claims (1)

[Claims] 1. A method for producing a polyether sulfone by polycondensing a dihalogenodiphenylsulfone compound and a dihydric phenol compound in an N, N-dimethylacetamide solvent in the presence of an alkali metal compound, wherein N, N- A method for producing a polyethersulfone, which comprises using N, N-dimethylacetamide having a tetramethylammonium chloride concentration of 50 ppm or less, which was recovered after producing the polyethersulfone as dimethylacetamide.