CS275981B6 - Polyphenylene oxide production method - Google Patents

Abstract

• In the oxidative polycondensation of 2,6-xylenol catalysed copper and copper complexes salts with amines in a mixed solvent aromatic hydrocarbon-aliphatic alcohol decreases a batch of at least 0.2% by weight of the particles polyphenylene oxide based on final weight of polymer less than 50 / µm amount of deposits on the walls and copper content , and diphenoquinone in the polymer. Can also be performed reaction when you do

Description

The invention relates to a process for the production of poly (2,6-dimethylphenylene oxide) by precipitation polycondensation, in which 2,6-dimethylphenol is used as a monomer and its reaction with oxygen is catalyzed by a complex of copper compounds with nitrogen bases and the polycondensation medium consists of a mixture of polymer solvent and non-solvent. .

Poly (2,6-dimethylphenylene oxide) (PPO) is a major thermoplastic, widely used in the form of polymer blends in a variety of industries. The breadth of its applications has reached a level unparalleled in other plastics. .

'A characteristic feature of PPO production is high energy consumption. (Plastics and Rubber, 20, 1983, Nos. 4, 97-98). All known technologies work with relatively high volumes of solvents; their regeneration is the most important item in the price balance. The main possibilities of cost minimization with regard to the relation of consumption in individual technological nodes are in increasing the concentration of xylenol in the condensation medium and reducing the consumption of solvents in the node of polymer isolation and washing.

The paths to these savings have not been known so far, they did not presuppose an increase in the final concentration of xylenol per unit volume of polycondensation medium while improving the granulanetric parameters, leading to more advantageous isolation and washing of the polymer in terms of solvent consumption.

The actual concentration of xylenol in polycondensation affects not only the course of condensation, but also a number of other factors, especially the amount of stickers and particle size distribution. Increasing the actual and final concentration of xylenol in polycondensation has a very adverse effect on these factors. The formation of the polymer takes place through an adhesive gel phase forming deposits on the heat exchange surfaces, in the particle size distribution of the precipitated polymer particles larger than 100 .mu.m predominate with a closed large volume of catalyst and polycondensation side products. These circumstances necessitate frequent renewal of the heat transfer surfaces of the condenser by washing with effective solvents. Concentrations of 50 g to 200 g xylenol / l of polycondensation medium are generally reported in the literature, but in practice the use of high concentrations is unrealistic and is around 100 g / l. We have now found that most of the barriers to reducing the volume of solvents in the polymerization as well as polymer isolation problems can be significantly reduced if the polycondensation is performed in the presence of a certain quantum of polymer particles added or formed into the polycondensation medium before starting the polycondensation. The PPO particles can be added to the polycondensation medium, for example also in the form of particles of a polycondensation suspension from a previous polycondensation.

The present invention relates to a process for the production of polyphenylene oxide by oxidative polycondensation of 2,6-xylenol catalyzed by complexes of copper and copper salts with amines and in an aromatic hydrocarbon-aliphatic alcohol mixed solvent, in which the mixed solvent feed in the reactor contains at least 0.2% by weight before polycondensation. of polyphenylene oxide to a weight of the final polymer having an average particle size of less than 50 .mu.m. ,

Known technological processes for the precipitation polycondensation of 2,6-dimethylphenol take place in a mixture of solvent and non-solvent polymer. The most commonly used solvent is an aromatic hydrocarbon, especially benzene or toluene, and non-solvents are alcohols, especially methanol, ethanol or isopropanol. Thus, the polymer particles in the polycondensation medium can be formed by ^{dissolving polymer 1} in a component of the condensation medium having solvent properties and precipitating it with a second component, i.e. a precipitant, the ratio of these components being selectable can be additionally adjusted to the required composition. The particles in the polycondensation medium can also be formed by another method, for example by adding a polymer solution in a volume of solvent corresponding to the desired equilibration of the solvent to non-solvent ratio required by the technological prescription. The optimal way to use our invention leading to the best results in terms of suitable particle size distribution, achieving the highest conversion of xylenols per unit volume of polycondensation medium and lowest consumption of washing medium in polymer isolation and washing is a process in which PPO particles are formed from polymer stickers on heat transfer surfaces reactor. At the same time, this operation can solve problems with the renewal of heat-walled surfaces, the efficiency of which is significantly reduced due to polymer deposits, and the renewal of which otherwise prolongs polycondensation cycles and increases solvent consumption.

The use and nature of our invention will become apparent from the following examples, ppm - parts per million by weight, DFCH - diphenoquinone% by weight in the examples, unless otherwise indicated.

Example 1 g of polymer with VC = 45 del. g was dissolved in 250 ml of toluene in a reactor thermostated at 40 DEG C. and 250 ml of methanol were precipitated immediately after dissolution. _{1.5 g of CuCl 2} and 60 ml of morpholine were successively added to the resulting suspension, and 147.5 g of xylenols dissolved in 1/2 1 of a 1: 1 mixture of toluene and methanol. After the addition was complete, the mixture was cooled to 39 DEG C. and further bubbled with oxygen for 15 minutes. After this time, the addition of O ₂ to the mixture was stopped, 60 ml was separated from the reaction mixture, and 5 ml of a 50% by volume solution of triethanolamine in methanol was added to the residue, the mixture was centrifuged, and the polymer filter cake was washed with 1.2 L of anhydrous ethanol at 1,100. rpm

After drying, 14 ppm Cu and 2 ppm OFCH were found in the polymer. Stickers on the reactor walls detected. The reactor was washed with chloroform. After evaporation of chloroform, the weight of the residue was 3.687 g, i.e. 2.5%. Conversion to xylenol 96.8%, particle size distribution is shown in Table 1. ’

Table

Granulometric composition of PPO prepared according to Example 1

'vel. particles / Uíll % 0 to 10 5 10 to 30 15 30 to 70 67 70 to 100 10 over 100 3.

Example 2.

The suspension separated from the polycondensation according to Example 1 was added to a 500-ml mixture of toluene and methanol (1: 1) (by volume) and the procedure of Example 1 was followed. 22 ppm of Cu and 7 ppm of OFCH were found in the polymer. The stickers on the reactor walls were 4.1%. The granulometric composition is shown in Table 2.

CS 275981 8 6

Table 2

Granulometric composition of PPO prepared according to Example 2

particle size / Um 0 to 10 7 10 to 30 20 30 to 70 ' 34 70 to 100 26 over 100 ' 13

Example 3

The polycondensation according to Example 1 was repeated. After emptying the polycondensation reactor, 250 ml of toluene were metered into the reactor and intensive circulation of toluene was maintained at 40 ° C for about 20 minutes, unless the polymer deposits in the reactor dissolved. With continued stirring, 250 ml of methanol was added to the resulting solution, and 1.5 g of CuCl ₂ and 60 ml of morpholine were added sequentially to the resulting suspension, followed by Example 1.

12 ppm Cu and less than 1 ppm DFCH were found in the polymer. ’.

The stickers on the walls of the reactor were 2.82 g, i.e. 1.9%.

The granulometric composition is shown in Table 3.

Table 3

Granulometric composition of PPO prepared according to Example 3

particle size / Ufll % 0 to 10 10 to 30 30 to 70 70 to 100 over 100 2 25 65 7 less than 1%

Example 4

Example 1 was repeated. However, no polymer particles were introduced into the polycondensation mixture before polymerization or during the condensation process. During the polycondensation, the temperature of the tempering bath had to be reduced from 18 ° C to 12 ° C in order to maintain a constant condensation temperature of 42 (-2) ° C.

88 ppm Cu and 26 ppm OFCH were found in the polymer.

The stickers on the walls of the reactor were 16.37 g, i.e. 11%.

The granulometric composition of the polymer is shown in Table 4.

CS 275981 B 6

Table 4

Ganulometric composition of the PPO prepared according to Example 4

particle size 0, / Lim 0 to 10 ' 13 10 to 30 4 30 to 70 9 70 to 100 17 over 100 57

Example 5

The experiment of Example 4 was repeated.

The polycondensation suspension obtained according to Example 4 was washed with ethanol until a negative reaction on OFCH in the effluent filtrate by spectrophotometric indication until the absorption at 420 nm disappeared. During washing, samples of the washed polymer were taken successively, dried and analyzed for Cu and OFCH content. Table 5 shows the dependence of the residual Cu content on the volume of the washing ethanol.

Table 5

- volume of washing ethanol 1 / kg impurity content in the polymer Cu (ppni) DFCH (ppm) 1.2 92 27 6.2 67 14 11.0 59 12 13.7 5 5 12

. PATENT CLAIMS

Claims (1)

. PATENT CLAIMS Process for the production of polyphenylene oxide by oxidative polycondensation of 2,6-xylenol catalyzed by complexes of copper and copper salts with amines and taking place in a mixed solvent aromatic hydrocarbon - aliphatic alcohol, characterized in that the mixed solvent charge in the stock contains at least 0.2% by weight of particles before polycondensation. polyphenylene oxide, by weight of the final polymer, of a size of less than 50 .mu.m.