CS229840B1 - Manufacturing process of polyphenylene oxide - Google Patents

Description

The present invention relates to a process for the preparation of polyphenylene oxide by oxidative polycondensation of 2,6-xylenol in the presence of catalysts.

Complex copper compounds with nitrogen bases are most often used as catalysts. The polymerization medium consists of either organic polyphenylene oxide solvents, i.e. in the case of homogeneous polymerization, or a mixture of solvents and precipitants. The second case involves precipitation polymerization. This process precipitates the polymer during oxidative polycondensation.

The solvent / solvent mixture used has essentially two meanings. First, it allows the catalyst to be operated in a homogeneous phase. Second, by selecting the ratio of solvent to solvent, the molecular weight of the polymer produced can be very conveniently controlled. The most commonly used solvents are aromatic organic compounds, especially benzene or toluene. In particular, alcohol, especially isopropanol, is used as a precipitant.

In virtually all cases of polyphenylene oxide preparation, isopropanol has a number of advantages over other alcohols as a precipitant. For example, mixtures of isopropanol with aromatic solvents such as benzene, toluene, xylene are excellent solvents for the vast majority of catalyst complexes based on monobasic or divalent copper compounds with nitrogen bases.

The mixtures are well analytically controlled and well separated on relatively simple devices.

Compared to other alcohols, polymerizations in mixtures containing Isopropanol show higher yields. It has now been found that the increase in yields is due to acetone produced during the polymerization by oxidation of a small proportion of isopropanol. Except acetone, all keto-containing substances generally have a positive effect on yield. Thus, for example, ethylmethylketone, acetophenone, caprolactam and the like increase the yield in addition to acetone.

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 complexes in mixtures of polyphenylene oxide solvents and precipitants, wherein the oxidative polycondensation is carried out in the presence of 0.5 to 10 weight percent. keto group.

The possibility of applying substances having a keto group in their structure is very wide.

In practice, the present invention can be used in all known polyoxidation polymerization processes of phenols. The compounds are active not only when using catalyst complexes of monovalent and divalent copper compounds, but also when manganese complex catalysts are used.

This effect is achieved in the case of heterogeneous but also homogeneous polymerization.

An increased yield was already observed in the presence of 0.5% by weight of the substances of the mentioned type. A pronounced effect occurs at concentrations of 1 to 10% by weight, preferably at 2 to 5% by weight.

The effect of adding substances having keto groups in the polymerization system in their structure is most pronounced in the temperature range of 15 ° C to 45 ° C.

The yield-temperature curve of these substances has a flat maximum in this region and the yield increase over polymerizations without this group of compounds is on average lower by up to 5%.

It is best to add these types of compounds to the polymerization simultaneously with the catalyst, in all amounts at once. Said quantity Community ^one of these substances is meant to handle the whole polymerization, it is the weight of such a polymerization system after the dosing of all components. Indeed, polymerization processes are known in which certain components are dosed gradually for justified reasons.

It is preferred that said concentration of active ingredient containing a keto group in its structure does not fluctuate during the reaction. If the polymerization is carried out in a barbotage reactor and the active substance used has a low boiling point (e.g. acetone), the optimal concentration of the active substance must be maintained by adding it to the polymerization batch during the reaction.

The following examples illustrate the invention. The percentages given in the examples are by weight.

Example 1

The reaction mixture is formed by mixing 550 ml of methanol, 400 ml of toluene, 81 ml of acetone, 20.4 ml of morpholine, 86 g of 2,6-xylenol and 1.56 g of copper chloride at a rate of 1.5 liters per minute. The precipitated polyphenylene oxide was filtered, washed and dried to constant weight. Weighing yielded 73.16 g (85.6%). Repeating the experiment without adding acetone yielded 79.4% polyphenylene oxide.

Example 2

Simes formed by mixing 20 ml of cyclohexylamine, 86 g of 2,6-xylenol, 600 ml of benzene, 400 ml of ethanol, 1.92 g of crystalline copper chloride and. 50 g of caprolactam was heated to 50 ^Q C and vigorously stirred for 45 minutes in a closed reactor under a oxygen atmosphere. The decrease of oxygen in the space above the liquid surface was supplemented with oxygen and maintained by means of pressure Oz liquid at constant pressure manostat 10,11.10 N m ^{4 second}

The precipitated polyphenylene oxide was filtered, washed with benzene / ethanol 6: 4 by volume and dried to constant weight. Weighing yielded 74.03 g (86.1)

Repeating the experiment without adding caprolactam gave 78.8% polyphenylene oxide.

Example 1 a d 3

100 ml of xylene, 50 ml of methanol, 3 ml of morpholire, 0.3 g of copper chloride were successively charged to a 300 ml polymerization, temperature-controlled, 50 ml Celsius reactor and 0.3 g of copper chloride was bubbled for 11 minutes with oxygen. Oxygen before introduction into the reactor was saturated with vapors of xylene, methanol and morpholine by passing through a 50 ° C washer, filled with 200 ml of the mixture in the same ratio as in the reactor.

At 12 minutes from the start of the barbotage, 12 ml of acetophenone was added to this mixture, and a solution of 10 g of 2,6-xylenol in 50 ml of a xylene / methanol mixture (ν '2: 1 v / v) was added over 14 minutes under constant intensive oxygen barbotage. After the entire volume of the xylenol solution was added, oxygen was bubbled through for another 20 minutes, after which time the precipitated polyphenylene oxide was filtered, washed successively with a mixture of xylene with methanol, methanol and dried to constant weight. 7%.

Repetition of the experiment without the addition of acetophenone yielded 80.2% polyphenylene oxide.

Example 4

A mixture of 260 ml of isopropanol, 740 ml of benzene, 1.72 g of crystalline cupric chloride, 18 g of benzylamine, 0.2 g of bromine, 100 g of 2,6-xylenol and 30 ml of methyl ethyl ketone was stirred vigorously at 40 ° C for 38 minutes in a sealed reactor. under an oxygen atmosphere. The oxygen loss in the space above the liquid level was replenished with oxygen and the O2 pressure was maintained similarly as in Example 2 at a constant value of 10.1 x ^{10 4} Nm ^-2 .

The precipitated polyphenylene oxide was filtered, washed with a mixture of isopropanol and benzene (2.6 to 7.4 by volume) and dried to constant weight.

Weighing ´ yielded 89.5 g, that is 89.5% polyphenylene oxide.

Repeating the experiment without the addition of methyl ethyl ketone yielded 86.1% polyphenylene oxide.

Claims (1)

Process for the preparation of polyphenylene oxide by oxidative polycondensation of 2,6-xylenol in the presence of catalytic amine-copper ion complexes in mixtures of lyphenylene oxide solvent and precipitants characterized in that the oxidative polycondensation is carried out in the presence of 0.5 to 10% by weight of substances having a structure keto group.