CS227586B1 - Method of preparing polyphenylene oxide - Google Patents

Description

(54) A method for producing polyphenylene oxide

The present invention relates to a process for the preparation of polyphenylene oxide by oxidative condensation of 2.6 xylenol in the presence of catalytic amine-copper complexes. This reaction can be carried out either in good polyphenylene oxide solvents or in solvent mixtures _; and non-solvents. In the first case, the polymer remains dissolved in the reaction mixture during the polycondensation and precipitates only after the oxidation reaction. In the latter case, the polymer gradually precipitates during the reaction.

The conditions of oxidation of phenols to the desired products i are studied in both methods very carefully and the synthesis of some products with significant properties is technologically mastered. They testify to it. wide patent documentation, publications in professional journals and commercial products prepared as described. The vast majority of publications of all kinds deal mainly with the factors influencing the course of the reaction and the representation of individual compounds in the final product.

In practice, however, there is no quantitative or qualitative classification of the parameters decisive for the particle size distribution of precipitation polyoxidation polymers.

From the technological point of view, the proportion of the finest polymer particles with a diameter below 25 μιη is decisive.

The nature of the particle size distribution of the polymer significantly affects the technological equipment, its economy and product processing. An inappropriate particle distribution adversely affects, for example, the polymer wash time, the consumption of washing liquids, the time and, of course, the resulting purity of the polymer. It also affects the drying process, the drift, the transport of the native polymer and possibly the homogenization of the polymer with the necessary additives before processing, etc. When studying the conditions affecting the particle size distribution of the prepared polymer produced by the precipitation polymerization, it was found that polyhenylene oxide whose cohesive energy density is close to that of polyphenylene oxide, which is estimated to be 0.34 to 0.38 GJ.m ^-3 .

SUMMARY OF THE INVENTION The present invention provides a process for the preparation of polyphenylene oxide by oxidative polycondensation of 2.6 xylenol in the presence of catalytic amine-copper ion complexes in solvent mixtures and 2.6 xylenol precipitators, wherein oxidative polycondensation is carried out in the presence of 1-10 vol% polyphenylene oxide precipitants. energy is in the range of 0.28 to 0.48 GJ.m ^-3 .

The cohesive energy of liquids E is usually calculated from the relation E = Lj / V, in which L _; is the internal heat of discharge and V is the molar volume of the substance.

Suitable aliphatic and cycloaliphatic ethers, aliphatic and cycloaliphatic ketones, simple esters, lactams, for example acetone (E = 0.407 GJ.m ^-3 ), methyl ethyl ketone (E = 0.3) are particularly suitable as precipitants of polyphenylene oxide with cohesive energy close to this polymer. 1 gJ.m ^-3 ), acetophenone (E = 0.298 GJ.m ^-3 ), ethyl acetate (E = 0.353 GJ.m ^-3 ), caprolactam (E = 0.455 GJ.m ^-3 ).

The presence of these substances in the polymerization system already at a low concentration very positively influences the particle size distribution in the sense that the proportion of particles of very small dimensions below 25 µm decreases rapidly depending on the concentration of these substances.

It has been found that the effect of these precipitants increases with the temperature of the oxidative polycondensation, which makes it possible to conduct the reaction at higher temperatures.

The addition of 1 to 10% by volume of the total polymerization batch volume significantly affects the particle size distribution.

Their optimum concentration is between 3 and 8% by volume, depending on the type of reactor and the polymerization temperature and boiling point of the active component used. In general, in technology with a barbotage reactor, higher polymerization temperature and lower boiling point of the active component, it is necessary to increase its concentration. If the polymerization is carried out in a closed reactor (the oxygen consumed is replenished to constant pressure), it is sufficient to produce the same effect by a quantity of active substances lower, on average about 1/2, under otherwise identical reaction conditions.

The following examples illustrate the invention. % by weight in the examples, unless otherwise indicated. ·

Example 1

This example illustrates the effect of the concentration of the substance of said group, in this case the acetone content. By injecting oxygen for 45 minutes into the barbotage-type reactor, 100 g of xylenol dissolved in 1 liter of ethanol-benzene mixture (50% by volume: 50% by volume) were polymerized at 50 ° C. The catalyst used was a complex of copper chloride with morpholine (1.2 g CuC1 ₂ .2H ₂ O + 21.2 ml of morpholine).

The polymer was isolated by centrifugation and washing of the catalyst residues by sequential washing with 5% hydrochloric acid in methanol and pure methanol. After drying to constant weight, a yield of 86% was determined by weighing and sieve analysis determined by% of the particle size fraction.

Oxidative polycondensation was repeated with the addition of different amounts of acetone, always at the beginning of the experiment. The results are shown in Table 1 below.

Table 1% of particles

% By volume of acetone in the polymerization mixture greater than 0.1 [them] 0.08 to 0.1 [mm] 0.025 to 0.085 [mm] smaller than 0,025 [mm] O 79.0 2.8 15.2 3.0 1 81.0 3.1 13.8 2.1 2 80.9 2.9 15.3 0.9 5 78.6 2.6 18.6 0.2 10 75.1 9.1 15.5 0.3 20 May 73.2 12.3 13.1 1.4

Example 2

The experiment of Example 1 was repeated at 18 ° C, 24 ° C, 30 ° C, 40 ° C, 50 ° C, 55 ° C. 5.6 vol% acetophenone was added as the active component. The results of a tapered screen analysis of the polymers prepared at these temperatures are shown in Table 2.

Table 2

Temperature % of particles greater than 0,1 [mm] 0.08 to 0.1 [mm] 0.025 to 0.08 [mm] less than 0.025 [mm] Deň: 18 ° C 48.4 8.1 28.6 14.9 Deň: 29 ° C 66.4 1.0 23.8 8.8 Deň: 32 ° C 70.5 7.6 17.4 2.5 . Deň: 32 ° C 80.9 2.9 15.3 0.9 High: 55 ° C 81.3 3.1 15.2 0.4

Example 3

This example illustrates the more general significance of the particle size distribution group described, also applicable under other polymerization conditions.

The conditions of the polymerization experiments and the results are summarized in Table 3. The proportion of particles smaller than 0.025 mm was determined by sieve analysis. These particles are the main cause of the mentioned technological difficulties.

Table 3

The polymerization conditions of Experiments 1 to 6 of Example 3 and their effect on a particle content of less than 0.025 mm. Recreation time polymerization I, 2 ... 60 minutes, 3, 4 ... 75 minutes, 5, 6 ... 45 minutes

Polyme- race number Catalyst Environment reaction Temperature reaction Noc: 2 ° C Active substance in polymerization mixture Proportion of particles smaller than 0.025 mm (%) species concentration (%) 1 (2.li) ² mol CuCl, azeotrope 50 - - 6.8 2 + 0.20 moles CHAI) ethanol, benzene 50 methyl ethyl ketone 10.8 1.0 3 (0.7.10 ^-2 mol CuCl azeotrope 50 - - 5.3 4 + 0.41 mol of pyridine); methanol, toluene 50 caprolactam 3.0 1.1 5 (10 g Cu + 4 g NH ₄ Cl isopropanol 52 - - 4.8 6 + 20 ml diisopropylamine)! xylene volume (1: 1) 52 ethyl acetate 10.01 3.0

CHA is cyclohexylamine

Claims (1)

SUBJECT Process for the preparation of polyphenylene oxide by oxidative polycondensation of 2,6-xylenol in the presence of catalytic amine-copper complexes in polyphenylene oxide solvent and precipitant mixtures INVENTION, characterized in that the oxidative polycondensation is carried out in the presence of 1 to 10% by volume of polyphenylene oxide precipitants having a cohesive energy density j in the range of 0.280 to 0.480 G.m · ³ .