JPS6055537B2 - Separation method of polyphenylene ether - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a resin synthesized from a phenol compound, and particularly to a method for separating a good solvent for polyphenylene ether and polyphenylene ether when producing polyphenylene ether.

The main object of the present invention is to obtain a dry polyphenylene ether that is finely divided, has little coloring, and has excellent quality. Polyphenylene ether is obtained by oxidative polymerization of phenols, and its manufacturing method is disclosed in Japanese Patent Publication No. 36-186.
It is well known from numerous domestic and international publications such as No. 9, Japanese Patent Publication No. 39-29373.

In the above method, polyphenylene ether is produced by adding a solution of polyphenylene ether obtained by oxidative polymerization to a mixture of a large excess of a non-solvent as a precipitant to the produced polymer and a large amount of acid for deactivating the catalyst. It is obtained by precipitating the polymer, separating it, and optionally washing it with a non-solvent for the polymer in order to remove catalyst residues and acids remaining in the polymer-containing solution, followed by heating and drying.

The operation of adding this polymerization reaction solution to a non-solvent is performed for the purpose of precipitating the polymer and removing the catalyst.

According to the method of Japanese Patent Publication No. 49-26318 filed by the present inventors, 2,6-
A dispersion of polyphenylene ether is obtained by performing oxidative polymerization of substituted phenol.

However, in this method, as shown in the Examples, when the proportion of the organic solvent that does not dissolve the polymer is increased, the degree of polymerization of the produced polymer decreases. Therefore, the proportion of organic solvent that can be used is limited. Further, since the third organic solvent is not added, the wet polymer separated from the dispersion thus obtained contains a large amount of the organic solvent that dissolves the polyphenylene ether. In such cases, lumps of molten polymer are produced during heating and drying. If polymer lumps are mixed into the polymer powder, it may cause problems such as clogging when the powder is stored, transported by air, or otherwise handled.

Furthermore, poor mixing tends to occur during the production of the polyphenylene ether resin composition, leading to deterioration in physical properties and poor appearance of the product. In more serious cases, the polymer melts and adheres to the dryer during drying, making the dryer inoperable. In this way, it is an extremely important issue in the industry to economically separate dry powder of polyphenylene ether into suitably fine particles from an organic medium containing a good solvent for polyphenylene ether.

A method disclosed in Japanese Patent Application Laid-Open No. 49-87799 is known to achieve this.

That is, by spraying a solution of polyphenylene ether into a hot inert gas and recovering the solvent, the polyphenylene ether is collected in the form of fine particles. No additional organic solvent is required in this method to separate the dry polymer. The examples also show that no lumps form in the dried polymer. However, this method has a serious drawback in that polymerization by-products such as diphenoquinone and low molecular weight substances contained in the polymerization reaction solution remain in the polymer, resulting in significant deterioration of product quality such as coloring.

Moreover, in order to overcome these drawbacks, complex pretreatments such as decolorization and terminal treatment are required. The present inventors have arrived at the present invention as a result of studies aimed at overcoming the drawbacks of conventional methods for obtaining dry powder of polyphenylene ether.

The present invention provides a novel method for obtaining dry polyphenylene ether powders.

The present invention provides a first organic solvent that dissolves polyphenylene ether, or a second organic solvent that mixes uniformly with the first organic solvent and does not dissolve polyphenylene ether, and a first organic solvent that dissolves polyphenylene ether.
This is a method of separating polyphenylene ether from polyphenylene ether impregnated with a medium consisting of an organic solvent (hereinafter referred to as 1. good solvent impregnated polymer), and 3. This is achieved by bringing the first organic solvent into contact with the polymer and transferring the first organic solvent from the polymer into the medium containing the second and third organic solvents.

The good solvent-impregnated polymer can be obtained by separating a polyphenylene ether dispersion using a mixture of the first and second organic solvents as a medium and a polyphenylene ether dispersion obtained by polymerization reaction.

After bringing the third organic solvent into contact with the good solvent-impregnated polymer,
The dry polymer can be obtained by a conventional method well known to those skilled in the art of separating and drying a wet polymer. It is necessary to carry out the weight part ratio between 1:4 and 1:15.

Within this range, dry polymer particles with little coloring can be obtained. When separating polyphenylene ether and the first organic solution, the first organic solvent
By being impregnated with rene ether, the third
It becomes possible to reduce the amount of organic solvent.

Since the polyphenylene ether obtained by the method of the present invention does not contain polymer lumps, it does not cause troubles such as clogging during transportation or storage, and does not cause poor mixing when producing a resin composition.

Moreover, a polymer of excellent quality with little coloring can be obtained. The method of the present invention will be described in detail below.

The polyphenylene ether as used in the present invention is a polymer obtained by oxidative polymerization reaction from a 2,6-monosubstituted phenol represented by the following formula.

In the formula, R. R'' is hydrogen, a hydrocarbon group having 6 or less carbon atoms, a halogenated hydrocarbon group (provided that there are at least 2 carbon atoms between the halogen atom and the phenol nucleus)
, an alkoxy group having 4 or less carbon atoms.

Among these, 2,6-dimethylphenol is representative. The first organic solvent for dissolving polyphenylene ether may be any solvent as long as it dissolves polyphenylene ether, but aromatic hydrocarbons and halogenated hydrocarbons are usually used.

Aromatic hydrocarbons include benzene, toluene, xylene, ethylbenzel, styrene, diethylbenzene,
Examples of halogenated hydrocarbons include methylene diclide, chloroform, dichloroethylene, trichlorethylene, tetrachlorethylene, dichloroethane, trichloroethane, etc.
Examples include tetrachloroethane and bromoform.

Examples of the second and third organic solvents include the following.

That is, alcohols such as methanol, ethanol, n-propanol, IsO-propanol, n-butanol, IsO-butanol, tert-butanol, cyclopentanol, cyclohexanol, petanol, and hexanol. Ketones such as acetone, ethyl methyl ketone, diethyl ketone, methyl isobutyl ketone, and di-n-propyl ketone. pentane, hexane, heptane,
Aliphatic hydrocarbons such as octane and their isomers, cyclopentane, and cyclohexane. Methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-acetate
-butyl, isobutyl acetate, sec-butyl acetate, acetic acid-n
- Esters such as amyl and isoamyl acetate. These are ethers such as diethyl ether, di-n-propyl ether, di-n-butyl ether, and furan. Using the same type of second and third organic solvents also has the advantage of simplifying solvent recovery.

The mode of bringing the good solvent-impregnated polymer into contact with the third organic solvent will be described in more detail. When bringing the good solvent-impregnated polymer into contact with the third organic solvent, the weight part ratio of the first organic solvent to the total of the second and third organic solvents is 1:4 to 1.
: Implemented in the range of 15.

If the weight part ratio of the second and third organic solvents becomes smaller than this and the ratio of the first organic solvent increases, drying becomes extremely difficult. Moreover, even if the ratio is made larger than the above range, the effect will not be further improved, and on the contrary, the amount of organic solvent used will increase, which will be economically disadvantageous. More preferably 1
:5 to 1:15.

Within this range, a highly purified dry polymer can be obtained in the form of fine particles. Furthermore, the amount of liquid contained in the good solvent-impregnated polymer is 20 parts by weight or less, usually 20 to 15 parts by weight, of the organic medium per 10 parts by weight of the polymer. Therefore, the amount of the third organic solvent used is extremely small in the case of polyphenylene ether impregnated with a good solvent. It is highly desirable from an industrial standpoint that a small amount of non-solvent can be used to separate the finely divided dry polyphenylene ether.

This is because it not only improves the solvent consumption rate but also has the advantage that the energy burden of distilling and recovering the solvent becomes extremely small. When the above-mentioned system is brought into contact with the non-solvent for the polymer, it can be used as long as it is below the boiling point of the mixed solvent, but it is usually preferable to bring it into contact with the non-solvent for the polymer at around room temperature.

Furthermore, when bringing the good solvent-impregnated polymer into contact with the third organic solvent, the non-solvent may be used in several portions. When repeating the contact separation between the polymer impregnated with a good solvent and the non-solvent, using the non-solvent in countercurrent can remove the first organic solvent impregnated into the polymer with a small amount of non-solvent, This is a preferred method because it facilitates drying.

Furthermore, it is also possible to use different types of non-solvent in the case of several contacts with the non-solvent. These operations may be performed continuously or batchwise.

In the present invention, it is also possible to perform operations such as stirring to facilitate the contact operation.

Hereinafter, the content of the present invention will be specifically illustrated in Examples.

In the examples, a 16-mesh sieve was used, and the percentage of what passed was shown. Generally, particles having a particle size larger than this are caused by melting and agglomeration during drying, resulting in an increase in particle size. Further, as a measure of the degree of purification of the polymer, the degree of coloration is used, which is obtained by comparing the absorbance of a chloroform solution of the polymer with a photoelectric colorimeter. The larger the value of the degree of coloring, the more significant the coloring of the polymer. In the Examples, the solvent composition was analyzed using a gas chromatograph. Example 1 Manganese chloride Mg, etaleramine 200g12,6
- A mixed solution of xylenol 1k9, benzene 2kg, and n-butanol 2kg is attached to a 5e with a cooler and an oxygen introduction tube.
Transfer to a reactor and circulate with a pump.

Oxygen was introduced at a rate of 3 e/min and the temperature was maintained in the 5's. The introduction of oxygen was stopped 3 hours after the start of the reaction. 1 kg of a 6% by weight hydrochloric acid aqueous solution is added to a dispersion of polyphenylene ether obtained by precipitation of the polymer during polymerization, and after stirring at 50° C., the mixture is allowed to stand to separate the aqueous phase. This extraction operation is repeated a total of two times. The polymer was separated by filtration from the polyphenylene ether dispersion thus obtained, and the liquid content was 100% (dry weight basis).
A wet polymer having a solvent composition of 7% by weight of benzene and 3% by weight of n-butanol was obtained. 200 g of this wet polymer is dispersed in 300 g of methanol, thoroughly stirred, and then filtered. This was dried at normal pressure and 150C using a cylindrical rotary dryer to obtain a dry polymer. The rate of passage through a 16 mesh sieve was 97%, and the degree of coloration was 8.

In this case, the third organic solvent used was 30 parts per 100 parts of polymer. Also, the total amount of organic solvent used is 7 (1)
It was hot at the club. Comparative Example 1 When the same operation as in Example 1 was performed using 180 g of methanol instead of 300 g of methanol, the passing rate through a 16 mesh sieve was 70% and the degree of coloration was 15.

Comparative Example 2 1k of polyphenylene ether 1% toluene solution
9 was poured into 2.7k9 methanol at room temperature with good stirring, and the precipitated polymer was separated and dried in a cylindrical rotary dryer at 150°C under normal pressure, resulting in polymer lumps. Ta.

The sieve passing rate was -30%. Comparative Example 3 In Comparative Example 2, instead of 2.7k9 methanol, 10
The procedure of Comparative Example 2 was repeated using k9 methanol.

The passage rate through the 16 mesh sieve was 97%.

In this case, the amount of the third organic solvent used per 100 parts of the polymer is 100 (4) parts, and the total amount of organic solvent used is 1
It was part 09(1). Example 2 Example 1 was repeated using n-hexane instead of methanol as the non-solvent for the polymer.

A similar operation resulted in a 16 mesh sieve passing rate of 97% and a degree of coloration of 9. Example 3 Example 1 was repeated using acetone instead of methanol as the non-solvent for the polymer.

By the same operation, the passing rate through a 16 mesh sieve was 97%, and the degree of coloration was 9. Example 4 Example 1 was repeated using diethyl ether instead of methanol as the non-solvent for the polymer.

By the same operation, the passing rate through a 16 mesh sieve was 97%, and the degree of coloration was 9. Example 5 Example 1 was repeated except that the amount of methanol used was 500 g.

By the same operation, the passing rate through a 16 mesh sieve was 99% or more. The degree of coloration was 6. Example 6 Example 1 was repeated using 250 g of methanol in two portions each.

By the same operation, the passing rate through a 16 mesh sieve was 99% or more. The degree of coloration was 4. Comparative Example 4 Polymer dispersion 4 obtained by extraction in Example 1
A polymer was obtained by distilling off the solvent from 00g by steam distillation as disclosed in Japanese Patent Publication No. 49-87799.

Claims (1)

[Claims] 1 Polyphenylene impregnated with a medium consisting of a first organic solvent that dissolves polyphenylene ether, or a second organic solvent that uniformly mixes with the first organic solvent and does not dissolve polyphenylene ether, and the first organic solvent. A third organic solvent that is a non-solvent for polyphenylene ether is added to the ether, and the total parts by weight ratio of the first organic solvent and the second and third organic solvents is in the range of 1:4 to 1:15. A method for separating polyphenylene ethers by contacting them in a similar manner.