SU1754732A1 - Method of producing polytetramethylene ester of glycol - Google Patents

Abstract

This invention relates to methods for producing polytetramethylene ether glycol (PTMEG). The invention allows to simplify the technology and reduce catalyst losses due to the polymerization of tetrahydrofuran (THF) in the presence of heteropoly acids, separation of the PTMEG solution in THF from the catalyst, distilling off a part of THF, and pre-purifying the PTMEG solution in the presence of 0.05 0.5% by weight of THF water, purification from traces of the catalyst using 1-10% by weight of a solution of pyridine polymer, its derivatives or alkylamine at 20-100 ° C for 0.5-10 hours, purifying the polymer solution from the catalyst, distilling off the solvent. 1table

Description

The invention relates to methods for producing polyesters, in particular polytetramethylene ether glycol (PTMEG) by polymerization of tetrahydrofuran (THF). PTMEG is used in the production of polyurethanes and products from them: leather, fibers, sealants, adhesives, etc.

The aim of the invention is to simplify the technology and reduce catalyst loss.

The essence of the proposed method is as follows.

THF is stirred in an inert atmosphere for 0.5–20 hours at 10–80 ° C with HPA heteropoly acids with a ratio of HPC:, 05–20, then the mixture is settled 0.1–1 h) until complete separation of the catalyst layers and the PTMEG solution in THF). the solution of PTMEG in THF, containing 1-10% of HPA, is separated, the THF is distilled to a concentration of PTMEG 50-90%, the organic solvent is added (hydrocarbons with 1-15 atoms

carbon) in the amount of 0.5-5 of the amount of the PTMEG solution and water in the amount of 0.05-0.5% of the amount of the initial THF. stirred for 0.5-5 hours at 40-100 ° C. the catalytic phase precipitated from the solution is separated (solution of HPA in THF-water mixture), which is returned to the polymerization reactor, 1-10% of the nitrogen-containing solvent is added, stirred for 0.5-10 hours at 20-100 ° C, the formed the precipitate is distilled off the solvent mixture and get PTMEG. HPA is used as a catalyst - strong mineral acids of the general formula HhXMmOo, where X is a heteroatom1 SI, P, As, Sb. Ge, B- M-W, Mo, V, Nb; , m-2,5-12, 0 24-62 HPK usually contain a lot of water of crystallization.

To efficiently carry out the polymerization reaction, it is necessary that the CCP contains 1-10 moles of water per CCP molecule. This is achieved by drying the CCP before the reaction at 150-300 ° C for 1-3 hours.

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The water content is 5 molecules. You can also use anhydrous CCP, but control the water content in THF (within 0.05-0.5%). The presence of water is necessary because it is consumed during the reaction:

pС4НвО + Н20 - ОН- (С4Н80-) П-Н.

A small amount of excess water against the stoichiometry may be present in the reaction mass. The total amount of water should be 0.05-0.5% of the amount of THF. According to the present invention, it is most expedient to feed all the water required for polymerization into the apparatus for the preliminary purification of PTMEG and HPK. In this case, the advantages are achieved: acceleration of the separation of the HPC solution from the PTMEG solution, the possibility of pumping the HPC solution into the polymerization reactor with a pump (in the presence of water, the HPA solution in THF becomes liquid).

Aliphatic or aromatic hydrocarbons with 1-15 carbon atoms or their halogenated derivatives, for example, pentane, hexane, heptane, octane, nonane, benzene, toluene, xylenes, are used as the organic solvent used for the preliminary purification of PTMEG from HPA. , cyclohexane, cyclooctane, their isomers, chloroform, carbon tetrachloride, freons, chlorobenzene, tetrachloroethane, isopropyl bromide, isobutyl chloride, and the like.

For final purification of the GPK PTMEG used nitrogenous solvent which is selected from the pyridine, methylpyridine (picoline), dimetilpiri- dynes (lutidines) piperidine metilpiperi- dynes (pipecoline), pyrrolidine, ethylenediamine, diethylamine, hexylamine, etc. . It is necessary that the solvent has a boiling point in the range of 20-180 ° C, is stable and affordable, and easily mixed with PTMEG. The nitrogen-containing solvent is an organic base that binds the acid in solution (HPA) to form an insoluble salt. Salt precipitated as a large precipitate is easily separated by any known method. The amount of nitrogen-containing solvent 1-10% of the amount of the PTMEG solution is necessary for complete precipitation of β-HPA. Increasing the amount of solvent by more than 10% will lead to energy costs for separating the mixture of solvents after the separation of PTMEG. Sludge formation occurs within 0.5-10 hours at 20-100 ° C. At a temperature below 20 ° C, the formation of sediment is difficult

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Allows for a low viscosity of the solution; exceeding the temperature of 100 ° C requires an increase in pressure to prevent the solution from boiling.

After separating the precipitate, the nitrogen-containing solvent together with the residual THF and the organic solvent is separated from the PTMEG by distillation. Salt of the CCP with a nitrogen-containing base is easy to regenerate in the CCP by known methods.

The proposed method to teach the ash-free PTMEG, practically not containing the CCP. The content of the CCP in PTMEG is less than 0.005%, which meets the requirements of Specifications 15-02-646-81 and the results obtained by the prototype method. At the same time, the technology of obtaining PTMEG is simplified: it is easy to transfer the catalytic phase from the preliminary purification stage of the HPC to the polymerization reactor by increasing its flowability, reducing the laboriousness of the PTMEG purification stage from HPC traces and reducing the loss of HPA when using nitrogen-containing solvent instead of solid sorbents. In the prototype, 0.1-0.5% of the CCP is lost.

PRI me R 1. In a 200 ml reactor with a stirrer, 50 g of heteropoly acid and 100 g of anhydrous THF are charged. The mixture is stirred for 4 hours at 60 ° C under nitrogen atmosphere, then set aside for 10 minutes. The mixture is exfoliated, the upper layer (a solution of PTMEG in THF) is separated by THF to a concentration of 5% PTMEG (the amount of solution is 20 g), while part of the HPC drops out of the solution as a solution in THF, which is sent to the reactor for polymerization and 30 g of octane and 0.5 g (0.5% of the initial THF) of water are added to one evaporated solution of PTMEG, stirred for 0.5 h at 100 ° C, and the precipitated phase of the solution of HPA in a mixture of THF- water that is recycled to the polymerization reactor. 5 g (10% of the amount of the PTMEG solution) pyridine was added to the PTMEG solution, stirred for 0.5 h at 105 ° C, and the precipitate was filtered on a large-porous filter. A mixture of THF, octane and pyridine is distilled off at 120 ° C to obtain PTMEG as a colorless or slightly yellow, viscous liquid. The results are presented in table 1.

PRI mme R 2. Reaction

polymerization

THF in the presence of H4SiWi2CMo-5H20 and purification of PTMEG is carried out as in Example 1, but 2-picoline is taken instead of pyridine. 9 g of polymer are obtained with a CCP content of 0.0001%.

Example The reaction of polymerization of THF in the presence of H / iSiW OwSHaO and purification of PTMEG is carried out in the same way as in Example 1, but instead of pyridine, take triethylamine. Get 9 g of polymer containing less than 0.0001% of the HPC.5

Example 4. A 200 ml reactor with a stirrer is charged with 50 g of H SiWiaCMo 5 HgO m 100 g of anhydrous THF. The mixture is stirred for 4 hours at 60 ° C under nitrogen atmosphere, then set aside for 10 minutes. The mixture is stratified, the upper layer of the PTMEG solution in THF) is separated. The THF is distilled to a PTMEG concentration of 50% (the amount of solution is 20 g), while part of the CCP precipitates from the solution as a solution in THF, which is sent 15 to the polymerization reactor. 30 g of benzene and 0.05 g (0.05% of the initial THF) of water are added to one stripped off solution of PTMEG, stirred for 5 hours at 40 ° C, and the precipitated phase of the solution of HPA in 20 mixtures of THF-water is recovered, which is returned polymerization reactor. 0.5 g (1% of the amount of the PTMEG solution) of 2.5-lutidine is added to the LTMEG solution, stirred for 10 hours at 20 ° C, and the precipitate is filtered off. A mixture of benzene, THF and lutidine is distilled off at 120 ° C to obtain PTMEG as a colorless viscous liquid. The polymer yield 10%, the content of the CCP is less than 0.0001% .30

EXAMPLE 5 THF polymerization is carried out in a continuous manner, which is carried out according to the scheme shown in the drawing.

In the reactor 1 with a stirrer with a volume of 150 l 35 load 50 kg of acid HUSiW CMo-l-bO and 100 kg of anhydrous THF, stirred for 1 h at 60 ° C. This forms a catalytic phase — a solution of HPA in THF. Then, anhydrous 40 THF with a flow rate of 25 kg / h is continuously fed to the reactor, and a solution of PTMEG vTHP is taken from the upper part of the reactor with the same flow rate. In the stripper 2, the THF is distilled off, while part of the dissolved HPA drops out of the solution, which is sent back to the polymerization reactor. A solution of PTMEG from apparatus 2 with a flow rate of 10 kg / h enters the apparatus 3 for preliminary purification from the CCP, into which nonane is supplied with a flow rate of 10 kg / h and water with a flow rate of 50 0.05 kg / h (0.2% of the amount of initial THF) . The residence time of the solution in the apparatus is 2 hours, the temperature is 70 ° C. From the lower part of the apparatus 3 to the reactor 1 the catalytic phase is continuously pumped out; its consumption is about 0.5 kg / h. Next, the PTMEG solution is fed into the apparatus 4 of the final purification from the CCP, which receives pyridine at a rate of 0.3 kg / h (1.5% of the amount

solution P | MEG). The residence time of the solution in the apparatus was 42 hours at 70 ° C. When this occurs, a precipitate forms, which is collected at the bottom of the apparatus. Then, a solution consisting of 50% of nonane, 20% THF, 30% PTMEG and 1.5% pyridine is sent to apparatus 5, where a mixture of solvents is distilled off at 120 ° C, followed by rectification process. Purified PTMEG is obtained at the outlet of the steam tank. For 20 hours, 40 kg of PTMEG with a GPC content of 0.0001% was obtained. During this time, apparatus 4 forms 0.5 kg of sediment consisting of a CCP salt with pyridine. The precipitate is removed from the apparatus and is used to obtain CCP NzR L / 1204o by a known method. The yield is 0.405 kg, which is 100% based on the LuS. The regenerated HPA is sent to the polymerization reactor to continue to produce PTMEG.

PRI me R b (prototype).

The reaction of THF polymerization and pre-purification of PTMEG from HPA is also carried out as in Example 5, but water is not supplied to apparatus 3, but to reactor 1, instead of the nitrogen-containing solvent, powder MDO is fed to apparatus 4 with a flow rate of 0.25 kg / h. For 20 hours, apparatus 3 accumulated 10 kg of the catalytic phase in the form of a resin that could not be pumped by the pump during operation of apparatus 3. To filter the PTMEG solution from MDO through a finely porous filter, it was necessary to increase the pressure in apparatus 4 above atmospheric. After 20 h, 40 kg of PTMEG were obtained with a CCP content of 0.0025% and 5.4 kg of powder of composition 7.4%. Regenerating the CCP from such a mixture is not economically viable. Irreversible loss of HPA was 0.5% (5.35 g, per 1 kg of PTMEG).

Claims (1)

Invention Formula The method of producing polytetramethylene ether glycol by polymerizing tetrahydrofuran in the presence of heteropoly acids as a catalyst, separating a solution of polytetramethylene ether glycol in tetrahydrofuran from the catalyst, distilling a part of tetrahydrofuran, pre-purifying the polytetramethylene ether glycol solution to the tetrahydrofuran as a connection to a tetrahydrofuran solution, and pre-purifying the polytetramethylene glycol ether glycol solution to remove the tetrahydrofuran solution. distilling off the solvent, characterized in that, in order to simplify technology and reducing catalyst losses, preliminary purification of the polymer solution is carried out in the presence of 0.05-0.5% by weight of tetrahydrofuran water, and 1-10% by weight of the polymer solution is used as an organic solvent to remove traces of heteropoly-sputter pyridine, its derivatives or alkylamine at 20-100 ° C for 0.5-10 hours, followed by separation of the precipitate. The results of the synthesis of PTMEG using different GPK