NL8400148A - METHOD FOR PURIFYING POLYETHERS AND / OR COPOLYETHERS WITH AT LEAST A LIMITED SOLUBILITY IN WATER. - Google Patents

Description

M.O. 322M 1

Method for purifying polyethers and / or copolyethers with at least a limited water solubility.

The invention relates to a process for the purification of polyethers and / or copolyethers with at least a limited water solubility based on epoxyethane and / or epoxypropane, so that they can serve as a suitable raw material for the preparation of hydrophilic polyurethanes and other products. Removal of residues of catalysts of the polyaddition or copolyaddition, such as hydroxides of alkall metals and of products of side reactions of the polyether synthesis, is mainly the matter.

The production of polyurethanes requires that the content of alkali metals in polyethers be less than 5.10 wt.% (5 ppm). While the purification of water-insoluble polyethers or polyether sols to polyether polyols, for example, prepared by polyaddition of epoxypropane to diols to polyols, is protected by many patents and inventor certificates, on the other hand, purification of water-soluble ethers and copolyethers is primarily of the ions of alkall metals still problematic. Therefore, removal of alkali metal hydroxides from water-insoluble polyethers is based on their neutralization with aqueous solutions of sulfuric or organic acids, primarily dicarboxylic acids (see British Pat. Nos. 916,552 and 958,390). Alkaline catalysts are further adsorbed on magnesium silicates at a temperature of 80 to 130 ° C in the presence of a small amount of water. Silicates are then removed by filtration (U.S. Patent 4,129,718). Methods for removing alkaline catalysts from water-insoluble polyols so that alkaline catalysts are extracted by water are also known, which accelerate extraction by dissolving polyols in hexane (U.S. Pat. No. 3,715,402) or alkaline catalysts are neutralized with oleic acid together with alkylbenzenesulfonic acid or with alkyltoluenesulfonic acid, if necessary (German patent application 2,737,473). Polyols are further purified from bases using a suitable solution of potassium hydrogen sulfite at a temperature of 20 to 130 ° C and a pH of 6.5 to 7.5. Precipitated salts are filtered after removal under reduced pressure from water (Polish Patent 94,408). In a similar way it protects

East German Patent 71,622, the removal of the alkaline catalyst by 8400148 by means of an aqueous solution of sodium hydrogen sulfate. It is also known (German patent application 3,016,112) alkali metal salts from crude emulsions, from the neutralization of alkaline catalyst in a water-insoluble polyether 5 with sulfuric acid in the presence of 1 to 30% by weight of water and 0 to 30% by weight of an organic solvent.

The drawback of the above-mentioned processes is mainly that they are only suitable for purifying water-insoluble polyethers. In addition, in the case of using water or water-containing solutions, a large amount of heat is necessary for distilling the water. The above-mentioned drawbacks are eliminated and technical problems for purifying water-soluble polyethers are solved by the process of the present invention.

According to the present invention, the process for purifying at least partially water-soluble polyethers and / or copolyethylers based on epoxyethane and / or epoxypropane of a catalyst, namely ions of alkali metals or undesired mixtures from the manufacture, if necessary, carried out by purification with 20 acids or acidic reacting compounds, mainly from the group of the ion exchangers, inorganic or polyhydric organic acids, preferably orthophosphoric acid, in an amount of 0.3 to 2.0, preferably 0, 8 to 1.1 moles per mole of catalyst, in the presence of a solvent, sorbent or chemical decolorizer, if necessary, with subsequent removal of insoluble fractions by filtration or centrifugation.

A high efficiency of removal of alkali metal cations or alkali metals from polyethers or copolyethers is the advantage of the method of purifying at least partially water-soluble polyethers of the present invention. Thus, treated -4-4 polyether or copolyether contains less than 3.10 or 1.10 wt% alkali metal cations and the polyether or copolyether is suitable for the preparation of polyurethanes.

The ability to simultaneously remove other substantially colored blends from polyethers and in particular a low energy requirement for purification are further advantages.

The purification process of the present invention does not require any expensive equipment and can be carried out continuously, discontinuously or semi-continuously.

40 In the case of a concrete realization of the working method according to the

8 4 0 0 1 4 S

In the present invention, more variants may be used which are suitable for the respective manufacturer or user of polyethers or copolyethers depending on the circumstances. The term polyether or polyether diol to polyether polyol according to the present invention is understood to mean products of the homopolyaddition of epoxyethane or epoxypropane, therefore also polyethylene glycol and polypropylene glycol, furthermore products of the polyaddition of epoxyethane and epoxypropane to diol to polyol or optionally the mixtures thereof. By the term copolyether, on the one hand, products are meant of the copoly addition of epoxyethane with epoxypropane, usually products of block polyaddition, in which, for example, the polyaddition of epoxypropane is carried out on polyethylene glycol or the polyaddition of epoxyethane on polypropylene glycol. Copoly addition can also start with other diols or with polyols such as glycerol, trimethylol-15 propane, pentaerythritol, triethanolamine and the like. The present preparation of polyethers or copolyethers is carried out under the catalytic action of bases, mainly hydroxides of alkali metals or Lewis acids. The catalyst or catalyst residues should be resp. must be removed from the produced polyethers or copolyethers for a wide variety of technical applications. At the same time, it is convenient to ensure that polyethers are flowable at temperatures up to 150 ° C. In the event that this requirement cannot be easily met, it is possible to proceed in such a way that the polyether is diluted with a suitable solvent, eg with an alcohol with a small number of carbon atoms. Water can also be used as a diluent, in the case where ions are removed by cationic ion exchangers or anionic ion exchangers.

Use of alcohols such as methanol or isopropanol and the like is suitable because these alcohols do not dissolve sodium and potassium salts. Alkali metal salts can then be easily removed using conventional separation methods such as filtration and centrifugation. Except for the removal of alcohols from solutions by distillation, a considerably smaller amount of heat is required than for the removal of water. In addition to the proposed solvents, it is also possible to use non-active solvents or diluents, such as ketone, acetone, methyl ethyl ketone and dimethylformamide. If they are used for the preparation of polyurethanes by solution technology, in this case they need not be removed from the polyether. Preparation of 8 * 001 '3 4 <4 from microporous polyurethane materials can serve as an example.

When inorganic acids are used, the sodium and potassium salts actually used, for example phosphates, sulfates, carbonates and chlorides, are insoluble in polyethers or polyether diols and the precipitate thus obtained can be removed by filtration or optionally another separation method. For this reason, it is expedient to use anhydrous acids and substantially polyvalent acids, mainly ortho-phosphoric acid, which is moreover suitable from the viewpoint of low corrosion of construction materials. With the use of orthophosphoric acid, even an overdose above normal does not matter, because the acid salts of sodium and potassium in polyether or copolyether are also insoluble. Similarly, the salts of sulfuric acid are not dissolved in alcohols and in acetone.

In the actual practice of the process of the present invention, a stoichiometric amount of orthophosphoric acid, optionally an excess of 10%, is preferably added, depending on the amount of catalyst employed or present (sodium or potassium hydroxide) in the crude polyether or copolyether. The solution is mixed for about 20 minutes, heated to a temperature of 80 to 120 ° C and usually held thereon for 20 to 30 minutes and then the resulting precipitate is filtered off. The process can also be carried out such that the content of alkalis in the solution of polyether diol or polyether is determined by acidimetric titration and according to the result of the determination, the amount of acid necessary for precipitation is used.

In case the polyether diol is dark, optionally activated charcoal or a chemical decolorizing agent such as sodium sulfite, hypophosphorous acid or sodium hypochlorite can be added to the solution before sedimentation of the alkali metal salt takes place. Active charcoal is then filtered off together with precipitated salt, preferably potassium phosphate and / or sodium phosphate.

Deionization can also be accomplished by ion exchangers, anionic and / or cationic ion exchangers. They are used in the 0H ^ ^ or form. In addition, it is most suitable to use continuous or semi-continuous equipment in which polyether or polyether diol or copolyether or optionally its solution is passed through the tower filled with ion exchangers. The towers are suitably tempered for the reason that polyether was less viscous. The most suitable sequence of ion exchangers is anion exchanger-cation exchanger. An anion exchanger has except 9400143

Ut * 5 that it captures any residues of anions, a decolorizing effect on polyether or copolyether. Ions of sodium and potassium are then captured almost quantitatively by the cation exchanger. The ion exchange capacity of ion exchangers can be determined or investigated by titration with an acid or a hydroxide and the sodium or potassium content in the product is usually determined photometrically.

Regeneration of ion exchangers is usually carried out using suitable solvents of acids or hydroxides with 10 washes until neutral reaction with distilled water, the concentration of acid or hydroxide being 3 to 5 wt.%. After removal of acid and hydroxides, the ion exchanger is washed with a low carbon alcohol or acetone alcohol to lose moisture. The process can be combined with the aforementioned precipitation with acids after removal of the salt by filtration. In the cases mentioned, a sodium and potassium content of less than 1.10 wt.% (1 ppm) is reached and a long service life of ion exchangers in the treatment cycles is ensured.

The proposed process achieves a high purity of poly-ethers or polyether sols and copolyethers, which are products suitable for the preparation of polyurethanes, at lower energy costs compared to processes using water.

Further details of the purification process of the present invention are evident from the examples, which nevertheless do not include all possible combinations of applications.

Example I

Two columns with an internal diameter of 3 cm and a height of 92 cm, provided with a jacket for the purpose of tempering using recycled liquid, are filled with ion exchangers 30. Column I with an anion exchanger (Lewatite S-10) and column II with a cation exchanger (Ostion KS). The volume of each wage exchanger is 500 cm3, ion exchangers were activated with 1500 cm3 of ggn solution of sodium hydroxide in water at a concentration of 5% by weight or with hydrochloric acid at a concentration of 35% by weight, at a volume rate of 3 hours. After conversion to the OH or the mold, the ion exchangers are washed with distilled water by feeding 1.5 parts by volume per part by volume of ion exchanger per hour for a period of 7 hours at a temperature of 80 ° C. After removing residues of hydrochloric acid or sodium 40 hydroxide (determination by monitoring the pH value), the ion exchangers are washed with isopropanol in an amount of 1500 ml for 8 h 8 0 14 8 + * ** 6 used to deionize crude water-soluble products from the polyaddition or copolyaddition of epoxyalkanes of 2 to 4 carbon atoms. The analysis results of these products after substantially purifying ions of alkali metals by ion exchangers in the order of anion exchanger-cation exchanger are presented in Table A. The crude water-soluble starting products simultaneously have a total potassium hydroxide or sodium hydroxide content of from 0.20 to 0.30 wt.% (Ie, 2000 to 3000 ppm) as determined by titration.

Whereas polyglycols or polyethers with a molecular weight greater than 1000 or copolyethers greater than 1500 at room temperature are too viscous, they deionize in the form of an n-butanol or aqueous solution at a concentration of 10 to 30% by weight at a temperature of 80 ° C. The solvent is evaporated under reduced pressure after deionization on a rotary evaporator. One ppm of polyether is purified by the cation exchanger so that the content of potassium cations is less than 3 x 10 wt.% (Below 3 ppm).

After experiments for the preparation of polyurethanes with 4,4'-di-20-phenylmethane diisocyanate in a nitrogen atmosphere, unmixed polyurethanes soluble in organic solvents such as, for example, dimethyl formamide, are prepared.

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Table A

The type of Molecular Content Content after deionization -4 crude pro weight ethoxamer [1.10 wt% of the [g.mol *] groups weight; ppm] polyaddition or [wt%] [Na ^ + ^] [K ^ +] copolyaddition_ polyethylene- 650 100 0.2 1.3 glycol polyethylene- 1080 100 0.0 0.3 glycol polyethylene- 1600 100 0, 1 0.63 glycol polypropylene- 920 0 0.2 1.1 glycol copolyether of 990 10 0.1 0.54 ethylene oxide and propylene oxide copolyether of 1500 42.5 0.0 0.57 ethylene oxide and propylene oxide copolyether of 2340 69.8 0.2 1.6 ethylene oxide and propylene oxide 8 4 0 0 14 8 8

Example XI

A copolymer of epoxypropane and ethoxyethane with a molecular weight of 1200 g / mol, a content of ethoxamer units of 52 wt% and potassium hydroxide of 0.22 wt% (2200 ppm) is treated by the addition of 0.59 moles of sulfuric acid and 1 mole of potassium hydroxide; 0.39 moles of orthophosphoric acid per 1 mole of sodium hydroxide; 1.09 moles of hydrogen chloride per 1 mole of sodium hydroxide; by 1.17 moles of butyric acid and acetic anhydride, and 0.41 moles of oxalic acid always per one mole of potassium hydroxide and bubbling through carbon dioxide.

After a 30 minute action of the acid or individual acids at a temperature of 25 ° C with stirring, the solution or the solutions are heated to a temperature of 80 ° C and after 30 minutes the precipitate formed is filtered off. The precipitate of potassium chloride filtered best. The others are in the series: 15 KCL> K3PO4 K2C03, K2S04>. K2 (CO0) 2.

When formic acid and acetic acid are used, the precipitate hardly occurs at all. The following amount of potassium ions is determined by ionoselective electrodes in the product [K ^]: 0.0170 wt% (170 ppm) with orthophosphoric acid, 0.0205 wt% (205 ppm) with 20 sulfuric acid, 0.0392 wt% (392 ppm) with hydrogen chloride, 0.0070 wt% (70 ppm) with carbon dioxide, 0.0166 wt% (166.5 ppm) with oxalic acid, 0.18 to 0.21 wt% (1850 to 2100 ppm) ) with formic acid and acetic acid.

The products are deionized after filtration using a cation exchanger (sulfonated copolymer styrene-divinylben- (+) 25-bitumen in the [H] form. The purification efficiency of the cation exchanger is simultaneously increased four times when hydrogen chloride is used (purification efficiency 10 dm ^). copolyether per 1 dm3 cation exchanger) and ten times when orthophosphoric acid is used.

Example III

A copolymer polyether having a molecular weight of 1200 g. Mol and a content of 30 wt.% Ethoxamer units and residues of the polyaddition catalyst in an amount of 0.23 wt.%, Mainly potassium hydroxide mixed with sodium hydroxide, is mixed with 35 different amounts of orthophosphoric acid mixed. After addition of orthophosphoric acid, the polyether is stirred at room temperature for 10 minutes and then at 120 ° C for 30 minutes, after which it is filtered hot. The content of sodium and potassium ions in the filtrate is determined spectrophotometrically.

40 The results of the influence of the amount of ortho-8400148 9 phosphoric acid added to samples of 500 g copolymeric polyethers with a molecular weight of 1200 g. Mole and a content of ethoxamer units of 30 wt.% And of potassium hydroxide of 0, 23 wt% with mixtures of sodium hydroxide are summarized in Table B.

5

Table B Addition 10 of H3PQ4 1.0 1.5 2.0 2.5 2.7 2.9 3.1 3.3

Is]

Addition of H3PO4 0.42 0.63 0.84 1.05 1.13 1.22 1.3 1.38 15 Imol.mor1 KOH]

After purification: content [K ^] 190 1 73 1 52 3.7 3.0 0.0 0.0 0.0 [1.10-4 wt. Z] 20 content [Na (+)] 3.3 2 1.2 1.9 0.0 0.0 0.0 0.0 0.0 [Ï10 "4 wt.%] PH 9.9 7.7 6.4 4.5 3.8 - 25

The required amount of orthophosphoric acid or other acid can be determined by straight titration with an acid at a pH below 6. In case the pH drops below 6.0, calcium carbonate is added to the product (eg in an amount of 0.6 wt. Z) to neutralize the free acid and then, while stirring, it is heated to a temperature of 120 ° C and the solution is further filtered after about 10 minutes. When the water-soluble polyether is dark-colored before purification, it is suitable to add 1.5 wt. Active charcoal and filter the solution after 20 minutes before adding the acid. Filtration of active charcoal can optionally be combined with filtration after neutralization of the base. The solution is decolorized according to the described method. A similar discoloration is achieved by the use of sodium 40 sulfite. In case of acid overdose, this excess is removed using an anion exchange column using 84 0 0 1: 8 10.

Treatment with the orthophosphoric acid using one mole of acid per one mole of the alkaline catalyst does not require further purification of polyethers or copolyethers with ion exchangers.

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Claims (1)

Process for the purification of polyethers and / or copolyethers with at least limited water solubility on the basis of epoxyethane 5 and / or epoxypropane of a catalyst, namely alkali metal ions or any undesired mixtures from the manufacture, characterized in that the perform purification with acids or acidic reactants selected from the group consisting of ion exchangers, inorganic or polyvalent organic acids, preferably orthophosphoric acid, in an amount of 0.3 to 2.0, preferably 0.8 to 1.1 mol per mole of catalyst, optionally in the presence of a solvent, sorbent or a chemical decolorizer, after which the insoluble fractions are removed by filtration or centrifugation. * * 8400148 Improvement of errata in the description associated with patent application 84-0014-8 pre-ordered by applicant, dated February 29, 1984 5, line 35: 5 Change "3 hours -" * · "to" 3 liters of liquid per liter of ion exchanger per hour ". 8, lines 6 and 7: change "sodium hydroxide" to "potassium hydroxide" j ... ^ ^ 8400148