CS256661B1 - Method of polyphenylenoxide's oligomers mixture insulation with copper from mother liquors after 2,6-xylenol's polymerization into polyphenylenoxide - Google Patents

Abstract

The solution relates to a method of isolation mixtures of oligomers with copper from mother liquors after polymerization of 2,6-xylenol to polyphenylene oxide. Mother liquors lightly distilled off volatile components are extracted with water or alcohols. The insoluble part it contains polyphenylene oxide oligomers together with metallic copper is isolated.

Description

The invention relates to a process for the isolation of a mixture of copper oligomers from mother liquors after polycondensation of 2,6-xylenol to polyphenylene oxide.

In the oxidative polycondensation of 2,6-xylenol, the catalytic system used has the greatest influence on polyphenylene oxide (PFO). Therefore, the prevalence of attention in the study of the course of catalytic oxidation is devoted to the choice of catalyst complexing agents. Catalytic systems based on monovalent copper salts with primary or secondary amines, divalent copper compounds with tertiary amines and divalent copper compounds with primary or secondary single alkylamine or ammonia have been proposed.

In technical practice, the polymerization medium for the oxidative polymerization of 2,6-xylenol consists of a mixture of an aromatic hydrocarbon with an alcohol, for example benzene or toluene, in combination with ethyl alcohol or methanol. The most commonly used catalyst system is a copper (II) or copper (I) chloride complex with an amine such as morpholine, cyclohexylamine and the like.

The precipitated polymer (polyphenylene oxide - PFO) is usually isolated from the polymerization medium by filtration. The filtrate (mother liquor), containing the oligomers of PFO, aromatic hydrocarbon, alcohol, copper (I) or copper (I) chloride with amine, is then subjected to separate processing.

The treatment of the mother liquor filtrates so far consists in injecting them into a film rotary evaporator or other type of evaporator and separating all volatile fractions on suitable rectification columns and returning them for reuse. A mixture of oligomers and the decomposition products of the catalyst system remains in or out of the continuously working evaporator. In order to improve the flow properties of the effluent, liquefiers, for example, oil, which is part of the feed of the mother liquor into the evaporator, are sometimes added. The isolation of copper from the evaporator thus obtained has not yet been addressed. The possibility of using this evaporator in practice, especially if it contains a plasticizer, is very problematic. In terms of quantity, it represents an important economic item.

Even without the liquefaction agent, the evaporators escaping from the thickening system - the evaporators still contain a considerable amount of amines, which make the evaporator plastic, soft to liquid and thus very difficult to handle. Its storage in metal containers is very limited because the evaporator is highly corrosive. In the description of the invention to U.S. Pat. No. 250,949 discloses a method of recovering copper from mother liquors by treating them with liquid extraction using an aromatic hydrocarbon-insoluble extractant such as water, ethylene glycol, glycerin, monoethanolamine, diethanolamine, and metallic copper precipitates from the severe polar phase after evaporation which is isolated by centrifugation or filtration.

SUMMARY OF THE INVENTION The present invention provides a process for the isolation of a mixture of polyphenylene oxide oligomers with copper from mother liquors after 2,6-xylenol oxidation polycondensation catalyzed by copper-amine complexes containing aromatic hydrocarbons, alcohols and amines. water or monovalent or polyhydric alcohols and the insoluble portion containing polyphenylene oxide oligomers together with metallic copper is isolated.

In addition to water, alcohols can be used for extraction. Of these, those forming part of the polymerization medium such as methanol, ethyl alcohol are most suitable, but ethylene glycol, glycerin and the like can also be used which very well extract from the concentrated mother liquor residues the residues of the non-distilled amines. As a result, the insoluble residue becomes very easily isolable by centrifugation, decanting or filtration and can be handled even after drying to a powder form.

The composition of the mother liquor is approximately: 35 to 50% by volume of the aromatic hydrocarbon, up to 65% by volume of alcohol, 0.5 to 4.0% by volume of water, 0.2 to 4.5% by volume of amines and 0.05 to 5% by weight of chloride copper or copper.

The advantage of this process is that the mixture of oligomers with copper metal can be extracted with mineral acids or by dissolving the oligomers in chlorinated hydrocarbons as an insoluble part by centrifugation or filtration.

A further advantage of this process is that the copper-oligomer mixture does not contain chlorine, which otherwise prevents its processing in the smelters.

When methanol or ethyl alcohol is used as extracting agents, these alcohols dissolve the oligomers of the lowest molecular weights, thereby allowing a mixture of oligomers with a significantly higher metallic copper content to be obtained.

Distillation - thickening of the mother liquors can be carried out on various types of evaporators operating under or without vacuum, continuously or discontinuously.

The following examples illustrate the invention. % in the examples are by volume.

Example 1 liters of mother liquor containing 43.4% toluene, 54.5% methanol, 1.0% water,

1.1% morpholine and 1.27 g / l of copper (II) chloride dihydrate are concentrated by distillation to a volume of 140 ml and extracted with 1500 ml of water. 50 g of a water-insoluble portion are obtained containing, in addition to the oligomers, 4.7 g of metallic copper.

Example 2

The procedure of Example 1 was followed except that an equal volume of methanol was used instead of water.

23 g of the methanol-insoluble part are obtained, containing, in addition to the oligomers, 4.7 g of metallic copper.

Example 3

The procedure of Example 1 was followed, except that an equal volume of ethyl alcohol was used instead of water.

24 g of an ethanol-insoluble part are obtained, containing, in addition to the oligomers, 4.7 g of metallic copper.

Example 4

The procedure of Example 1 was followed except that an equal volume of ethylene glycol was used instead of water.

37 g of an insoluble part are obtained containing, in addition to the oligomers, 4.7 g of metallic copper.

Example 5

Following the procedure of Example 2, only the mother liquors were concentrated to a volume of 170 ml. 20 g of a methanol-insoluble portion are obtained, containing 4.7 g of metallic copper.

Claims (1)

Process for the isolation of a mixture of polyphenylene oxide oligomers with copper from mother liquors after oxidative polycondensation of 2,6-xylenol catalyzed by a complex of amines containing aromatic hydrocarbons, alcohols, amines and alkanolamines characterized in that the mother liquors are concentrated by distilling off or monovalent or polyhydric alcohols and the insoluble portion containing the polyphenylene oxide oligomers together with the copper metal is isolated.