JPS62275126A - Purification of polyphenylene ether - Google Patents

Abstract

PURPOSE:To obtain a purified polyphenylene ether stable against heat oxidation and excellent in mechanical properties, electrical properties and dimensional stability, by treating a reaction product obtained by oxidatively polymerizing a 2,6-disubstituted phenol with sulfuric acid and steam-distilling the treated product. CONSTITUTION:A 2,6-disubstituted phenol of the formula (wherein R1 is a 1-4C hydrocarbon group and R2 is a halogen or R1) is oxidatively polymerized in the presence of an Mn salt/basic compound/amine catalyst in a solvent comprising a good solvent for a polymer, such as xylene, and, optionally, a good solvent for a catalyst, such as butanol. To the reaction product thus obtained a nonsolvent such as an alcohol or a ketone is added to precipitate the polymer, and the mixture is treated by adding 1-5 equivalents per equivalent of the total of the amine and the basic compound in the catalyst and filtered. The obtained wet polyphenylene ether is neutralized, dispersed in (hot) water and purified by removing the organic solvent, sulfates as by-products, etc., by steam distillation.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for purifying polyphenylene ether obtained by oxidative polymerization of J, O-disubstituted phenol.

Conventionally, oxidized polymers of 2,6-disubstituted phenols have been known as polyphenylene ethers, which have poor mechanical properties, electrical properties, heat resistance, etc., low water absorption, and poor dimensional stability. Due to its good properties, it has recently attracted attention as a thermoplastic engineering plastic.

(Conventional problems 1, 2 and problems) Generally, polyphenylene ether is dissolved in an organic solvent.
It is produced by oxidative polymerization of disubstituted phenol (2), but recovery and purification of polyphenylene ether from a polymer solution is common (2) is carried out after first extracting or decomposing the used catalyst, or at the same time as this operation. This is done by contacting with a non-solvent such as methanol.

Catalyst extraction and decomposition is done by Tokkosho! ; 3-'16360 (1) A method using organic acids such as hydrochloric acid or organic acids such as acetic acid; ) A method of adding a chelating agent for TA'4 has been proposed.

However, methods using hydrochloric acid or acetic acid have the disadvantage that the polymer exhibits significant discoloration during hot molding. Also,
It is known that the method of adding a chelating agent such as EDTA reduces the molecular stability due to the cutting of polymer chains during loading operation or heat molding. As shown in Publication No. 5-5, when the polymer is brought into contact with sulfuric acid, the terminals of polyphenylene ether (=existing hydroxyl groups and substituents at the co- and ot-positions undergo partial oxidation, and the generated hydroxyl groups become sulfuric esters and are protected. (Secondly, it is known to be very stable against thermal oxidation, but the extraction and decomposition of the catalyst (if sulfuric acid is used, NaOH or KO used for neutralization in the subsequent process)
Reaction with basic compounds such as Na2SO4 or 2S
Sulfates such as 04 are produced as by-products. Na2SO4 or So
Quaternary sulfates are virtually insoluble in solvents such as methanol and ethanol used during polymer recovery, so they remain in the polymer and cause adverse effects such as clouding the polymer and deteriorating water absorption. give.

As a result of intensive research into a method for separating and purifying polyphenylene ether, which is stable compared to thermal oxidation, the present inventors have discovered that thermal oxidation is possible by treating the reaction product with sulfuric acid and then steam distillation. (We have discovered that polyphenylene ether, which is more stable than the other two, can be obtained, and have completed the present invention.)

(Means for Solving the Problems) That is, the present invention provides for separating and loading polyphenylene ether from the reaction product obtained by oxidative polymerization of co-, di-substituted phenol. This is a loading method for polyphenylene ether, which is treated with 100% polyphenylene ether and then subjected to steam distillation.

The 2-di-substituted phenol used in the method of the present invention has the general formula (1) (wherein R1 is the number of carbon atoms) to a hydrocarbon group, and R2 represents a halogen or a hydrocarbon group having the number of carbon atoms/to . ), which are phenols represented by
For example, 2-dimethylphenol, 2-/f/
- Ethylphenol tylphenol, 2-ethyl-, 4-n-70 virphenol, λ-methyl-6-chlorophenol, -1-methyl-6-promophenol, 2-methyl-isopropylphenol, 2-ethyl-
-Methyl-Otsu- loaf' lobilphenol, Coethyl-Otsu-promophenol, Comethyl-≦-〇-butylphenol, Co-methyl-Otsu-n-propylphenol,
Examples include coethyl-chlorphenol.

These compounds may be used alone or in combination. Also a small amount of orthocresol,
Even if it contains meta-cresol, para-cresol, co-dimethylphenol, co-ethylphenol, etc., there is no practical problem.

Among these 2,6-disubstituted phenols, especially (nico,
O-dimethylphenol is important.

The polyphenylene ether used in the present invention is obtained by oxidative polymerization of 2,6-disubstituted phenol using various catalysts.

Specifically, the method using a manganese salt-basic compound-amine catalyst system (Japanese Patent Publication No. Sho J''7-4TG Otsu No. 2J), the method using a manganese chelate catalyst system (Japanese Patent Publication No. Sho J'' 9-2/
fri No. 5), basic No. 2'IA salt-diamine-3
A method using an absorbing amine-secondary monoamine-hydrogen bromide catalyst system (JP-A-Sho!; No. 3-301.91), cobalt salt-
Method using an amine catalyst system (Special Public Interest Publication No. 73 @
Oxidative polymerization can be carried out by i).

The method of the present invention (; As long as the polymerization medium to be used is one that is less likely to be oxidized than the phenols to be oxidized and has no reactivity to various radicals that are thought to be generated in the middle of the reaction process, Although there are no particular restrictions, it is preferable to use a material that can dissolve a phenol derivative and a polymerization catalyst. Examples of such materials include aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene;
Chloroform, /,;, -v halogenated hydrocarbons such as chloroethane, trichloroethane, chlorobenzene, dichlorobenzene, nitrated @ compounds such as nitrobenzene, etc. can be used as good solvents for polymers, and methanol, ethanol, Alcohols such as propatool, benzyl alcohol, and cyclohexanol, acetone,
Ketones such as methyl ethyl ketone, esters such as ethyl acetate and formate, and ethers such as tetrahydrofuran and diethyl ether can be used as good solvents for the catalyst. Therefore, it is preferable to use a polymer solvent alone or a combination of a good catalyst solvent and a polymer solvent (secondarily, it is preferable to configure the solvent by a combination of two or more types. Depending on the combination ratio of this polymer good solvent and catalyst good solvent The polymerization method can be a solution type method, or a late stage polymerization method (: precipitation polymerization method in which the polymer precipitates).

In the present invention (=), the method of treating the reaction product with sulfuric acid is specifically carried out, for example, by the following method.

After the polymerization reaction, methanol, ethanol, lovanol, 1so-7' lovanol, n
An alcohol such as -butanol, complex-butanol, iso-butanol, or tert-butanol, or a ketone such as acetone or methyl ethyl ketone is added to precipitate polyphenylene ether. The reaction product (= these solvents to be added are essentially non-solvents for the polymer, so they have the effect of precipitating the polymer. Then, sulfuric acid is added. Sulfuric acid may be added to decompose the catalyst and react with the hydroxyl groups in the polymer to improve the stability of polyphenylene ether against thermal oxidation. There is no problem at all. The amount of HzSO4tit added is sufficient to react with the basic components (amines, basic compounds) present in the reaction product. It is desirable to use it in slightly excess than the amount directly. - was added during the polymerization reaction (amine + basic compound)
/~5 times: Add Tsuji's 82804. Added)
The concentration of I2SO4 is not particularly specified, but from the viewpoint of operability and economy, a value of 7 to 9.5% H, So4 is desirable. The reaction product treated with H2SO in the method of the present invention (2) is filtered to obtain a moist polyphenylene ether containing the combined reaction powder.Since this is acidic, a polymer non-solvent such as methanol is again used. (- After dispersion, NaOH or KO
) (etc.). Through this process, a neutralized t'-containing polyphenylene ether is obtained.

In this neutralization operation, Na 2 SO4 or 2So
4 etc., MeOH, EtOH4 alcohols substantially (=
Insoluble sulfate is produced as a by-product. Steam distillation for removing the by-product sulfate is carried out, for example, by the method shown below.

The neutralized moist polyphenylene ether obtained above is bidispersed in water or hot water (bidispersed), and steam is blown into the system (steam distillation is performed from the second step. As the organic solvent in polyphenylene ether is removed (:, by-product/residual Na2SO4
Alternatively, sulfates such as 2S04 are removed. Steam distillation in the method of the present invention is carried out at reduced pressure, increased pressure, or normal pressure, and the temperature of the system can be controlled by pressure. Preferably, the pressure and the amount of steam blown are adjusted so that the temperature is 50 to 750°C. Steam distillation (
1. The time required is to perform steam distillation for 5 minutes or more, preferably 70 minutes to 3 hours.

(Effect of the invention) Separates and purifies polyphenylene ether (per 1
By treating the reaction product with FyL acid followed by steam distillation (2) and thermal oxidation (2) stable polyphenylene ethers can be obtained.

(Examples) Hereinafter, the present invention will be further described in detail with reference to Examples (2), but the present invention is not limited in any way by these Examples.

Definition of color index> Dissolve 0.52 of the polymer compression molded at 370℃ in chloroform, make the total amount 700-1.4t at 2.5℃
♂Measure the absorbance at 0 nm and calculate using the F format.

The value of the color index is used as a means of evaluating the degree of thermal oxidation of polyphenylene ether, and the lower the value, the less colored the polymer is due to heating, and the more stable it is than the thermal oxidation.

(Coloring index) ao smiling lo intensity of light from two people! =Intensity of transmitted light a: Cell length [1] b: Solution concentration [? [Shoulder] Example/Co, O-dimethylphenol/θOf (0.12 mol), xylene 2tlt09, butanol♂O? , MnCl2-NaO was dissolved in a mixed solvent of methanol♂Of.
In the presence of a H-N-methylethanolamine catalyst (dioxide polymerization is performed, Bo!J-(2,6-dimethyl-7,
A polymerization reaction solution of (cuphenylene) ether was obtained. Is the amount of catalyst used MnC6z (tetrahydrate)? (0,00F
2-fnyl), NaOH/, otcO, oyimol)
, N-methylethanolamine/, 2 f (0,0z
It was Otsumoru). Add 2 methanol to the obtained polymerization reaction solution.
¥01 was added to precipitate the polymer dissolved in the -line. This (= 7./f (0./g equivalent) of concentrated sulfuric acid) was added and stirred at 50° C. for 7 hours to complete the decomposition of the catalyst and the reaction with the OH groups in the polymer.

After filtering the above suspension, add methanol 30θ1 and suspend again.
．． Neutralized up to θ. This was filtered to obtain a medium-phase moist polyphenylene ether. Pour this into 0℃ hot water♂soy
Suspended in 'l 00?' and steamed under normal pressure. Steam distillation was carried out for 30 minutes by blowing at a flow rate of 71 r. During this time, the temperature inside the system was 29 to 93°C. After cooling, the polymer was filtered and dried under vacuum for 30 minutes at 1/1 °C to obtain polyphenylene ether powder. The ηs eva θ of the polymer at 30°C was 60. The color index of the 370°C heat-molded product is S, and the color index containing OlN a2804 is /
It was 20 ppm.

Comparative example / Substitute for sulfuric acid (23! Thihydrochloric acid / 9? (0, / Gutomin)
Polyphenylene ether powder was obtained in the same manner as in Example 1 except that 3/θ℃ heat-molded product was
Index is //, 3, NaCl-containing food is ♂o pp
It was m.

Comparative Example Instead of cosulfuric acid (=♂acetic acid, 4t? (0, / <i!:
A powder of polyphenylene ether was obtained in the same manner as in Example except that the same amount of polyphenylene ether was used. The color index of the 3/θ°C heat-molded product was /j,t, and the content of sodium acetate was /701)I)m.

Comparative Example 3 The color index of a 370°C heated molded product of a polymer obtained by vacuum drying the neutralized moist polyphenylene ether obtained in the middle of Example/ without steam distillation is j,! , Na2SO4 content is 3. Otsu00p
It was pm.

Example 2 Polyphenylene was added to the polymerization reaction solution (2) in the same manner as in Example except that methanol was added to the solvent shown in Table 1, and NaOH used in the middle phase was added to the basic compound shown in Table 7 (2). Ether powder was obtained and evaluated.

Table 7 shows the results.

Table / Table Examples 7 to 10 The weight of methanol added to the polymerization reaction solution shown in Table 2, and the added weight of %H, So, are used in place of the (equal number of liters) shown in Table 2. Polyphenylene ether powder was obtained and evaluated in the same manner as in Example except for the above. Table 2 shows the results. - Table 2 Examples//~/6 The pressure during steam distillation, the amount of steam blown, and the steam distillation time were prepared in exactly the same manner as in Example/, except for the changes shown in Table 3 (2). The results were shown in Table 2.

Claims (1)

[Claims] In separating and purifying polyphenylene ether from the reaction product obtained by oxidative polymerization of 2,6-disubstituted phenol, the reaction product is treated with sulfuric acid, and then,
A method for purifying polyphenylene ether characterized by steam distillation