PL229964B1 - Method for producing poly(phenylene oxide) with high molecular weight - Google Patents

Abstract

A method is disclosed for producing poly(phenylene oxide) with an assumed, regulated, high molecular weight by oxidative polymerization of 2,6-dimethylphenol (DMF), in a solvent/non-solvent system, using a catalytic complex of a secondary amine with a copper (II) salt, which is carried out at a fixed solvent/non-solvent volume ratio and with a fixed amount of the catalytic complex, expressed as the DMF/Cu(II) molar ratio. The obtained product is intended for the production of foils and membranes.

Description

Description of the invention

The subject of the invention is a process for the production of a predetermined, controlled, high molecular weight poly (phenylene oxide) by the oxidative polymerization of 2,6-dimethylphenol. The product obtained by the process of the invention is intended for the production of films and membranes.

Poly (phenylene oxide) (PPE or PPO) is one of the most important engineering thermoplastic polymers which, due to its unique combination of good mechanical and electrical properties, high thermal and dimensional stability, as well as resistance to acid and alkali and other features, is widely used in many industries, incl. in the electronics, electrotechnical and automotive industries. One of the most important areas of application of poly (phenylene oxide) is membrane technology, enabling the recovery of both raw materials and energy media used in industry, as well as reducing the amount of chemical substances discharged into the environment as post-production waste, In separation techniques, membranes made of PPE, characterizing high selectivity while maintaining good functional properties, allow, among others, for selective gas separation, light paraffin and olefin separation. The factor determining the use of PPE in the membrane production process is the high molecular weight of the polymer - also expressed by the value of the intrinsic viscosity number (GLL), with the lowest possible polydispersity. Good performance films and membranes are made from PPE with a GLL greater than 0.8 dL / g, which corresponds to a number average molecular weight (Mn) greater than 60,000.

Poly (phenylene oxide) is produced by the oxidative polymerization of 2,6-dimethylphenol (DMF) in an atmosphere of molecular oxygen, catalyzed by a copper (I) or (II) salt system, in which the anion is most often Cl ^- , Br ^- , with an amine . In the reaction of PPE production, aliphatic monoamines, aliphatic diamines, cyclic amines and aromatic amines are used as amines. The reaction is carried out in a solvent or a mixture of organic solvents, i.e. aliphatic and aromatic hydrocarbons, halogenated aliphatic and aromatic hydrocarbons, alcohols, ketones and others. During the polymerization of DMF, in addition to the PPE polymer, by-products such as water and 3,3 ', 5,5'-tetramethyldiphenquinone (TMDCh) - a colored crystalline substance, giving the polymer an unfavorable color, lowering the reaction efficiency and deteriorating the properties of the obtained polymer. By establishing the composition of the catalytic complex and the reaction medium, PPE can be produced in a wide range of molecular weights. The factors influencing the molecular weight of the growing macromolecules po 1 and (phenylene oxide) are: reaction environment, composition of the catalytic complex, concentration of the catalytic complex expressed by the molar ratio of DMF / Cu, etc.

From US 4,028,341 there is known a method of producing PPE in a mixture of toluen-methanol in a weight ratio of 85/1, with a high molecular weight (GLL = 1.215 dL / g) by means of a catalytic complex in which DMF / Cu = 1100, consisting of from copper ions, bromine and secondary and tertiary amines, but due to, among others, Due to the difficulties related to the insulation of the polymer, the lack of repeatability of the batches in terms of the molecular weight of PPE, this method is not suitable for use on an industrial scale.

US Patent No. 6,472,499 B1 discloses a process for the preparation of PPE with a GLL> 0.8 dL / g, which uses a copper catalytic complex consisting of bromide ions, Quaternary. mono- and diamines and tertiary. monoamines. The reactions were carried out in toluene at a concentration of the catalytic complex (DMF / Cu) in the range of 100-200. The disadvantages of the presented method of obtaining PPE are the necessity to constantly monitor the increase in the molecular weight of the polymer and the disadvantageous procedure following the production of a polymer with a specific molecular weight. When the target molecular weight of PPE is reached, the reaction is stopped with an aqueous solution of nitrilotriacetic acid, and then, after separation of the organic phase from the aqueous phase, the polymer precipitant, i.e. methanol, is added to the toluene solution of the polymer. These additional steps reduce the efficiency of the process.

US 2011/0 293 937 A1 discloses a process for the preparation of PPE in toluene having a weight average molecular weight (Mw) above 150,000. The reaction is catalyzed by a copper amine complex where the amine is N, N'-dibutylethylenediamine, dimethylbutylamine and dibutylamine, at a molar ratio of DMF / Cu to 114. According to the described method, the PPE production process is carried out in three temperature ranges, i.e. 20-30 ° C, 30-40 ° C and 45-55 ° C, respectively, for an initiation step (exothermic step), a polymer growth step, and a product purification step. Upon reaching the specified molecular weight gain of the PPE, the reaction

The solution is interrupted by oxygen cut-off in the solution, and the polymer is precipitated in two steps. The produced PPE is characterized by high polydispersity and the difference (up to approx. 38%) between the GLL of the PPE obtained at the end of the reaction, and the GLL of the finished product.

US 4,537,948 describes a method for the preparation of PPE by the polymerization of 2,6-dimethylphenol in a toluene / methanol medium, catalyzed by the morpholine / Cu system. Compared to the method according to US 4 537 948, the use of (on average) four times more morpholine in the catalytic system [morpholine / Cu ratio] and much less Cu (II) ions with respect to DMF [DMF / DMF ratio] in the process according to the present invention. Cu (II) (on average) from two to more than four times higher], with even twice the excess of Br ions to Cu ions, it is possible to obtain a polymer with a high molecular weight of at least 0.8 dL / g, which according to the invention No. US 4,537,948 ranged from 0.60 to a maximum of 0.86 dL / g.

Unexpected relationships were found between the action of a specific catalytic complex and the composition of the toluene / alcohol system and the molecular weight of the PPE homopolymer obtained. The figure (Fig. 1) shows the dependence of the GLL of the obtained polymer on the methanol content in the solution with toluene for fixed amounts of the catalytic complex (DMF / Cu).

According to the invention, the preparation of PPE with an assumed, regulated high molecular weight (GLL> 0.8 dL / g) in the toluene / methanol (ethanol) system consists in determining two parameters: the appropriate alcohol concentration in a mixture with toluene, expressed in% by volume, and the appropriate concentration of the catalytic complex, expressed as a DMF / Cu molar ratio, depending on the expected molecular weight of the PPE, expressed by GLL.

A method of producing poly (phenylene oxide) with an assumed, controlled, high molecular weight - expressed as the intrinsic viscosity number (GLL) - of at least 0.8 dL / g, by oxidative polymerization of 2,6-dimethylphenol (DMF) in the toluene system / methanol (ethanol), using the catalytic complex of morpholine with copper (II) bromide, with the presence of free hydrogen bromide, with a fixed volume ratio of toluene / methanol (ethanol) in the range of 90/10 to 50/50, respectively, according to the invention it consists in this that the polymerization is carried out with a fixed amount of the catalytic complex, expressed as the molar ratio of DMF / Cu (II), in the range 150-350, where the molar ratio of Cu (II) / HBr / morpholine in the catalytic complex ranges from 1 / 4/60 to 1/6/100.

In the process according to the invention, the amount of the catalytic complex, expressed as the DMF / Cu (II) molar ratio, set in the range 150-280, is preferably used.

Preferably, a catalytic complex formed by reacting copper oxide (CuO) with an aqueous solution of hydrogen bromide, dissolving the salt in methanol or ethanol, and then reacting with morpholine is used.

Preferably, in the process according to the invention, the toluene / ethanol volume ratio is set in the range from 90/10 to 65/35, more preferably in the range from 85/15 to 70/30.

Preferably, in the process according to the invention, the toluene / methanol volume ratio is set in the range from 90/10 to 60/40, more preferably in the range from 82/18 to 70/30.

The Cu / HBr / morpholine catalytic complex used in the process according to the invention does not exhibit catalytic activity in the known and used methods of obtaining PPE in toluene solution. The introduction of alcohol to toluene, i.e. carrying out the process of PPE preparation in the solvent / polymer non-solvent system, activates the action of the catalytic complex used. This complex, composed of copper (II) bromide, morpholine and hydrogen bromide, is a very active catalyst for the oxidative polymerization of DMF in the toluene / alcohol system. The method of its preparation and the molar amounts of ingredients used have a significant impact on its activity. The complex is most preferably obtained by reacting copper oxide (CuO) with a concentrated aqueous hydrogen bromide solution (preferably 48 wt% commercial product). The reaction product is dissolved in alcohol and the morpholine is dosed in, keeping the temperature below 35 ° C. The obtained catalytic complex is completely soluble in the reaction medium, which facilitates its contact with the reactants during the process of PPE preparation. The activity of the catalytic complex depends on the molar ratios of the components used. The molar ratio of the used: hydrogen bromide and copper (II) (HBr / Cu) ranges from 4 to 6. The molar ratio of the used copper (II) and morpholine (Cu (II) / morpholine) ranges from 60 to 100. The molar ratios between all components of the catalytic complex based on 1 mole of Cu (II) used (Cu / HBr / morpholine) range from 1/4/60 to 1/6/100.

PL 229 964 B1

The figure (Fig. 2) shows the dependence of the GLL of the PPE obtained on the amount of the catalyst complex used, expressed as the DMF / Cu ratio, for a methanol concentration of 20 vol.%. in a mixture with toluene.

The drawing in Fig. 1 and Fig. 2 illustrates the method of determining the process conditions (alcohol concentration, amount of catalytic complex) to obtain PPE with a predetermined molecular weight value.

The process of PPE preparation consists in dosing a DMF solution in a toluene / alcohol mixture at a predetermined concentration to a solution of the catalytic complex in a toluene / alcohol mixture and, at the same time, oxygen with a bubbler immersed in the reaction mixture. The dosing of the DMF solution is carried out from 1.5 to 3.0 hours, usually from 2 to 3 hours. The oxygen dosing is kept at a rate such that the oxygen concentration in the nitrogen-diluted exhaust gas is less than 7.0 vol.%. The process requires intensive agitation, preferably with the use of a turbine agitator. The process is exothermic and requires cooling so that the temperature in the reactor does not exceed 35 ° C, and is most preferably kept in the range of 25-30 ° C. At this stage of the process, 70 to 85% of the stoichiometric amount of oxygen required by the process is reacted. Upon completion of the dropwise addition of the DMF solution, the PPE oligomer in GLL is obtained in the range 0.1-0.2 dL / g. The oligomer is reactive, "living" and polymerizes in the next step in the process.

Oxygen is introduced into the obtained oligomer. The reactive oligomers are polymerized and the process is in a solid, swollen state. The oxygen is introduced at a rate such that the oxygen concentration in the nitrogen-diluted exhaust gas is less than 7 vol.%. The process is less exothermic than the oligomerization step, but requires cooling so that the temperature does not exceed 35 ° C and is most preferably kept in the range of 25-30 ° C. As the reaction progresses, the degree of oxygen conversion decreases. The process is complete when oxygen uptake to the reaction mixture ceases. At this stage of the process, 15-30% of the stoichiometric amount of oxygen required for the process is reacted.

After the end of the process, PPE is separated from the reaction mixture in a highly swollen form. After introducing additional alcohol in such an amount that the final alcohol concentration in the solution with toluene was 40% vol. for ethanol and 50 vol. for methanol, PPE is isolated in the form of a precipitate, which is washed successively with alcohol and dried. Unexpectedly, it turned out that by carrying out the process of PPE preparation with the amount of the catalyst expressed as DMF / Cu below 300, a polymer with a very low content of by-product (TMDCh) is obtained. The use of an increased amount of morpholine in relation to DMF inhibits the production of TMDCh.

PPE is obtained with the assumed, regulated, high molecular weight (GLL) resulting from the alcohol concentration in the mixture with toluene and the amount of the catalyst complex used, expressed as the DMF / Cu molar ratio.

The following examples illustrate the practice of the invention.

P r z k ł a d 1

Preparation of the catalytic complex.

1.304 g of hydrobromic acid (48%) are added to a glass flask with a stirrer, containing 0.1141 g of copper (II) oxide. After dissolution, 10 ml of methanol are introduced followed by 11.08 g of morpholine. The temperature is kept below 35 ° C at all times. The ratios of the components in the thus obtained complex are Cu (II) / HBr / morpholine = 1 / 5.4 / 88.1.

The course of the polymerization process

The reaction is carried out in a reactor with a capacity of 0.5 dm ³ , equipped with a high-speed stirrer (500 rpm), a heating and cooling jacket, a thermocouple, an oxygen inlet stub immersed in the reaction liquid, a cooler, an oxygen supply regulator and an exhaust gas meter. The catalyst complex solution for polymerization is prepared in the reactor by mixing 12.0 cm ^{3 of} methanol, 90.0 cm ^{3 of} toluene and the catalyst complex prepared as above. To obtain a DMF solution, mix 90.0 cm ^{3 of} toluene, 23.0 cm ^{3 of} methanol and 48.8 g of crystalline DMF. DMF / Cu (II) ratio = 280.

After setting the temperature of 25 ° C in the reactor, the pump dosing the DMF solution is started at such a speed as to stop dosing after 2.5 h and, at the same time, oxygen is dosed at a rate of 4 dm ³ / h, while observing the readings of the oxygen concentration meter Oxygen content in the gases did not exceed 7% vol. during the entire process of obtaining poly (phenylene oxide). The temperature of the reaction mixture was kept at around 28 ° C.

PL 229 964 Β1

After the dispensing of the monomer solution was completed, the oxygen supply was continued. The amount of oxygen absorbed was controlled. After the reduction in oxygen uptake was observed, the flow was gradually reduced and the administration of oxygen was terminated when the uptake ceased completely, which lasted for 2 hours.

^{A solution of acetic acid in methanol (8 cm 3 of} concentrated acetic acid + 135 cm ^{3 of} methanol) was added dropwise to the reactor to deactivate the catalytic complex and fully precipitate the polymer. The polymer was filtered off, washed several times with methanol and dried.

The thus obtained poly (phenylene oxide) is characterized by GLL = 1.06 dL / g, M _n = 69 348, M _w = 269 154, Mw / Mn = 3.8 and contains 0.008 wt. TMDCh.

Example 2

The reaction is carried out in the reactor described in Example 1.

The catalyst complex solution for polymerization is prepared in the reactor by mixing 18.25 cm ^{3 of} ethanol, 84.25 cm ^{3 of} toluene and the catalyst complex prepared as in Example 1, but using ethanol instead of methanol.

To obtain a DMF solution, mix 84.5 cm ^{3 of} toluene, 28 cm ^{3 of} ethanol and 48.8 g of crystalline DMF.

The next steps are as in example 1.

The thus obtained poly (phenylene oxide) is characterized by GLL = 0.80 dL / g, M _n = 66 690, Mw = 131 531, Mw / Mn = 2.6 and contains 0.004 wt. TMDCh.

Example 3

Preparation of the catalytic complex.

1.5144 g of hydrobromic acid (48%) are added to a glass flask with a stirrer, containing 0.1325 g of copper (II) oxide. After dissolution, 22 cm ^{3 of} methanol are introduced, followed by 12.8 g of morpholine. The temperature is kept below 35 ° C at all times.

The polymerization is carried out in the reactor described in example 1.

The solution of the catalyst complex for polymerization is prepared in the reactor by mixing 90 cm ^{3 of} toluene and the catalyst complex prepared as above.

To obtain a DMF solution, mix 90 cm ^{3 of} toluene, 23 cm ^{3 of} methanol and 30.5 g of crystalline DMF.

The next procedure is as in Example 1, with the difference that the oxygen is introduced at a rate of 2 dm ³ / h.

The thus obtained poly (phenylene oxide) is characterized by GLL = 2.11 dL / g, M _n = 396 969, Mw = 634 830, Mw / Mn = 1.6 and does not contain TMDCh.

Example 4

The reaction is carried out in the reactor described in Example 1.

The catalyst complex solution for polymerization is prepared in the reactor by mixing 102.8 cm ^{3 of} toluene, 34.3 cm ^{3 of} ethanol and the catalyst complex prepared as in Example 3, but using ethanol instead of methanol.

To obtain a DMF solution, mix 102.8 cm ^{3 of} toluene, 34.3 cm ^{3 of} ethanol and 30.5 g of crystalline DMF.

The next steps are as in example 2

The thus obtained poly (phenylene oxide) is characterized by GLL = 0.80 dL / g, M _n = 113 126, M _w = 359 219, Mw / Mn = 3.2 and does not contain TMDCh.

Table 1 List of examples

Example Methanol | vol.% Eianol |% vol Toluene |% vol4 DMF / Cu jmol / mol! GLL IdL / gj Ί TMDCh J wt. | Ł twenty - 80 280 1.06 69 348 269 154 3.8 O, tH58 2 - 25 75 280 0.80 66 690 13 Ϊ 531 2.6 0.004 3 twenty - 80 150 2.1! 396 969 634 830 J, 6 lack 25 75 150 i, iis 113 126 359 219 3.2 lack

Claims (5)

1. A method for the production of poly (phenylene oxide) with an assumed, controlled, high molecular weight - expressed as the intrinsic viscosity number (GLL) - of at least 0.8 dL / g, by oxidative polymerization of 2,6-dimethylphenol (DMF), in toluene / methanol (ethanol) system, using the catalytic complex of morpholine with copper (II) bromide, with the presence of free hydrogen bromide, with a fixed volume ratio of toluene / methanol (ethanol) ranging from 90/10 to 50/50, respectively, characterized by: that the polymerization is carried out with a fixed amount of the catalytic complex, expressed as the molar ratio of DMF / Cu (II), in the range of 150-350, while in the catalytic complex the molar ratio of Cu (II) / HBr / morpholine is in the range of 1/4 / 60 to 1/6/100. A method according to claim 1, characterized in that the amount of the catalytic complex is used, expressed as the molar ratio of DMF / Cu (II), set in the range 150-280. 3. The method according to claim 1, characterized in that the catalytic complex is formed by reacting copper oxide (CuO) with an aqueous solution of hydrogen bromide, dissolving the salt in methanol or ethanol, and then reacting with morpholine. The method according to claim 1, characterized in that the toluene / ethanol volume ratio is set in the range from 90/10 to 65/35, more preferably in the range from 85/15 to 70/30. 5. The method according to claim 1, characterized in that the toluene / methanol volume ratio is set in the range from 90/10 to 60/40, more preferably in the range from 82/18 to 70/30.