TW200303880A - Reduction of the proportion of cyclic oligomeric ethers in polytetrahydrofuran or copolymers of tetrahydrofuran - Google Patents

Abstract

To reduce the proportion of cyclic oligomeric ethers in polytetrahydrofuran (PTHF) or copolymers of tetrahydrofuran (THF), the PTHF or THF copolymers are extracted at from 30 to 200 DEG C in one or more stages by means of an aliphatic, linear or branched or cycloaliphatic or olefinic hydrocarbon having from 4 to 15 carbon atoms, a mixture of such hydrocarbons or a mixture comprising at least 50% by weight of such hydrocarbons and the PTHF or THF copolymer phase and the hydrocarbon phase are separated from one another. The extraction is carried out in a column having a central stirrer which extends over a plurality of stirring zones located one above the other, with the ratio of the circumferential velocity of the stirrer to the power of three to the height of the stirrer being more than 0.5 m2/s3.

Description

200303880 (〇 Mei, invention) (The description of the invention should state: the technical field to which the invention belongs, the prior art, the content, the embodiments and the drawings are simply explained) Technical field Polytetrahydrofuran, hereinafter referred to as PTHF, also known as polycyclic Oxybutanediol is used in the plastics and synthetic fiber industries as a suitable intermediate in many ways. Among them, polyurethane elastomers, polyester elastomers, and polyamide elastomers are used. In addition, like Like some of its derivatives, it is a valuable adjuvant in many applications, such as as a dispersant, or for the removal of ink from waste paper. PTHF is generally industrially polymerized by the polymerization of tetrahydrofuran on a suitable catalyst (hereinafter (Called THF) to be prepared. The addition of appropriate reactants enables the chain length of the polymer chain to be controlled and thus allows the average molecular weight to be set to the desired value. These reactants are called chain terminators or "telomers" ". Control is achieved by selecting the type and amount of telogen. Choosing an appropriate telomer enables the additional functional groups to be introduced at one or both ends of the polymer chain. Therefore, For example, using carboxylic acids or carboxylic anhydrides as telomers can produce mono- or diesters of PTHF, which must then be converted to PTHF by saponification or transesterification. These procedures are therefore referred to as two-stage PTHF procedures Other telomers not only act as chain terminators, but also incorporated into the growing polymer chain of PTHF. They not only have the function of telomers but are also comonomers, so they can be equally appropriately called telomers Or comonomers. Examples of such comonomers are telomers having two hydroxyl groups, such as glycols (diols). For example, these may be ethylene glycol, propylene glycol, butylene glycol , 1,3-propanediol, 1,4-butanediol, 2-butyne-1,4-diol, 1,6-hexanediol or low molecular weight PTHF. Also suitable comonomers are cyclic ethers such as ( 2) 200303880

Such as 1,2-alkylene oxide, for example, ethylene oxide or propylene oxide, tetrahydrofuran or 3. methyltetrahydrofuran. Except for water, l: i 夂 methylon amount PTHF, the use of these comonomers leads to the preparation of tetrahydrofur = low fractions (hereinafter referred to as THF copolymers) and can be chemically modified in this way. Preparation is mainly carried out by a two-stage procedure, with examples. THF is polymerized in the presence of fluorosulfonic acid to form a ρτΗρ ester, and this ester is hydrolyzed to PTHF. Alternatively, for example, THF: described below is polymerized using acetic anhydride in the presence of a medium to form PTHF, which is a secondary acid, and then this diester, for example, is transesterified with methanol, and PTjjp For example, as described in European patent A 38 009 and German patent a 28 001 '. The single-stage synthesis of the prior art PTHF in 8 is known from the world patent WO96 / 〇39355, 'the surface is made by using water, 1,4-butanediol or low molecular weight PTHF as a telomerizing agent. Polymerization proceeds on the catalyst. The well-known catalysts include two systems: homogeneous dissolution into the reaction system and heterogeneous systems (ie, mostly undissolved), for example, the heteropolyacids known from European Patent B 126 471 and U.S. Patent No. 4,120,903 is known as a peracid Nafion® ion exchange resin. German patent A 44 33 606 describes the existence of one or a mixture of these telomers via water, 1,4-butanediol, PTHF and the like having a molecular weight from 200 to 700 daltons. A method for preparing PTHF by polymerizing THF on a heterogeneous catalyst, which is a supported catalyst that includes a catalytically active amount of an oxygen-containing hafnium or molybdenum compound or these compounds 200303880

(3) It is mixed with an oxide-supporting substance. After applying a precursor compound containing molybdenum and / or tungsten compounds containing oxygen, it is burned at 500 ° c to 1000 ° c. German Patent A 196 49 803 discloses that the activity of a catalyst described in German Patent A 44 33 606 is increased by an accelerator. A very large proportion of low molecular weight products are formed during the polymerization or copolymerization of tetrahydrofuran in the above and other procedures. These undesirable by-products include or include oligomeric cyclic ethers. They may be present in a proportion of up to 20% by weight, while forming a smaller proportion in a secondary procedure of polymerization or copolymerization than in a single-stage procedure. These oligomeric cyclic ethers are undesirable for many reasons. As inert compounds, they interfere with further processing of polymers, for example, they react with isocyanates to form polyurethanes. They act as plasticizers and often have an adverse effect on the mechanical properties of the finished product. They can also leak out of the surface of the finished product like sweat or be leached by solvent, which, for example, adversely affects the dimensional stability of the finished object. To remedy these shortcomings, German Patent A-35 14 547 proposes to extract a cyclic oligoether 'from a PTHF or THF copolymer by using a mixture of water and hydrocarbons and the polymer is recovered from the aqueous phase. A method for removing low molecular weight fractions from a PTHF or THF copolymer is disclosed in U.S. Patent No. A-3,478,109, in which a hydrocarbon solution of a polymer is extracted with an alcohol / water mixture. European Patent No. A_153 794 describes a method for reducing the content of oligomeric 5 curtain ethers in PTHF and THF copolymers, in which cyclic ethers are copolymerized from original PTHF or THF by smoking at 20 ° C to 60 ° C. Extracted. One disadvantage of the various procedures of the prior art is the relatively high residual quantity of 200303880

(4) The cyclic oligoether is still in the polymer, even after repeating these procedures. From the viewpoint of its polydispersity and color number, the obtained pTHF or the obtained THF copolymer could not meet the requirements. SUMMARY OF THE INVENTION An object of the present invention is to provide a simple and economically advantageous way to reduce the proportion of cyclic oligoethers in PTHF or THF copolymers having a molecular weight from 600 to 6000 to less than 1% by weight (based on pTHF Or THF copolymer). When the content of the cyclic oligoether is reduced to the required value, a linear polyTHf oligomer or copolymer based on the extractant should not be more than 3% by weight. The others found that this objective was achieved through measures specified in item i of the patent application. Advantageous specific embodiments of the procedure of the present invention are defined in the sub-items 2 to 7 of the patent application park. The PTHF or THF copolymer to be treated is prepared in a manner known per se in the presence of a strongly acidic catalyst in a single stage or via the esters of PTHF in two stages followed by hydrolysis and transesterification. . For example, PTHF can be prepared via a single-stage procedure as described in German Patent No. 33 606 or World Patent WO 96 /% 35, and therefore usually contains up to 10% by weight of cyclic oligoethers. Τ η F copolymers with 1,2 · alkylene oxides, such as ethylene oxide, can also be obtained by methods described in British Patent B-854 958 and German Patent β-3 346 134 but usually contain from 1 to 20 weight percent oligomeric cyclic ether. The selective removal of cyclic oligomers from PTHF or THF copolymers is based on 200303880 (5)

Use of aliphatic, cycloaliphatic or olefinic hydrocarbons having from 4 to 15 carbon atoms, preferably from 7 to 11 carbon atoms, or a mixture of these hydrocarbons or including at least 50% by weight of these Extraction of mixtures of hydrocarbons is achieved. Suitable hydrocarbons for this extraction include saturated and unsaturated aliphatic, and cycloaliphatic compounds, and also olefinic hydrocarbons, each of which may also have a substituent such as a prime atom or an alkoxy group. Priority is given to the use of saturated and unsaturated ' branched and straight chain aliphatic hydrocarbons. It is also possible to use any mixture of hydrocarbons, for example 'saturated aliphatic and cycloaliphatic hydrocarbons such as fe having from 4 to 5 carbon atoms such as butane, pentane and decane; branched alkanes such as 2- Methylhexane and isononane; cycloaliphatic hydrocarbons having from 5 to 12 carbon atoms such as cyclopentane, cyclohexane, cyclooctane, and cyclododecane; unsaturated aliphatic or cycloaliphatic ^ such as having The number of feminine hydrocarbons from 4 to 12 carbon atoms, such as isobutene and cyclohexene. The amount of hydrocarbons or hydrocarbon mixtures used in the extraction can be changed within a wide range of fields. In general, the weight of hydrocarbons: pTHF or THF copolymers is at least 0 · 5 · 1. In particular, it is in the range from 1: 1 to 10: 1, more than 2 from 1'5.1 to 5.1. Crude extraction is usually from 30 to 2⑼. It is performed under c, preferably from / G ° to 1GG ° C, particularly preferably from 8Gt. The pressure is based on the solvent vapor pressure at the selected stroke temperature T. Priority, given under 1 atmosphere. In addition, according to the present invention, the liquid / liquid extraction is carried out in one or several stages in a tower with a 3 ^ agitated state. The central agitator extends all the way up to the top. Two or more stirrers, preferably from 10 to 200, particularly preferably I WO stirring zones. The proper tower is suitable for extraction as it is cold -10- 25 200303880

(6) One phase of the well-known ritual tower has a relatively high viscosity (Wagner, Ι; 2000; TU Munich paper "Der Einfluss der Viskositat auf den Stofftibergang in Fliissig-Fltissig-Extraktionskolonnen"). An example is "Die "Chemische Produktion" (1979, December) as described in "SCHEIBEL," tower, QVF ENGINEERING stirred tank agitator and ΚϋΗΝΙ stirring tower ("Κ''ΝΙ tower"). An important parameter in agitated systems is epsilon. The measure of the maximum energy dissipation on the stirring element is the cube of the peripheral speed u of the agitator: the ratio of the height h of the agitator: ε ~ u3 / h When constant, for many agitators, use a value of 0.1: ε = 0.1 u3 / h For optimal extraction, a mixture of PTHF or THF copolymer with hydrocarbons is processed at a u3 / h ratio higher than 0.5 m2 / s3 (ε = 0.05 W / kg). As a result of this measurement, the mass transfer of the self-adhesive PTHF phase is significantly accelerated. Furthermore, wetting of the inside of the tower via the viscous dispersed phase is suppressed, as shown in the examples. Priority is given to extraction in stirred towers which have a stirrer height of 0.1-l * d and a peripheral speed above 0.15 m / s of 0.2-0.8 * D (D = inner diameter of the tower) The usual stirrer diameter (d). Therefore, for example, in the case of a blade agitator having an outer diameter of 40 mm and an agitator height of 8 mm, the peripheral speed successfully employed is 0.31 m / s. This value shows the u3 / h ratio (ε = 0.39 W / kg) at a stirrer of 3.9 m2 / s3. According to a further feature of the invention, the effectiveness of the extraction can be obtained in a mixing device installed directly upstream of the tower. Use hydrocarbons fully or partially saturated 200303880 880 PTHF or THF copolymers to improve. Possible mixing devices are agitating vessels, static or dynamic pipe mixers or a chestnut. The extraction according to the invention can reduce the content of cyclic oligoethers to less than 1% by weight (based on PTHF). After extraction, the PTHF or THF copolymer is separated from the hydrocarbon phase including cyclic oligoether and PTHF based on a small amount of the total amount by less than 2% by mass based on phase separation. Subsequent to distillation, the PTHF or THF copolymer phase is predominantly free of hydrocarbons remaining therein, i.e., hydrocarbon contents as low as 0.01 to i% by weight (based on PTHF), preferably as low as 0.05 to 0.5% by weight. Distillation can be carried out batchwise or continuously. Priority is given to single-stage or multi-stage evaporation, among which purified pTHF or stubs will be removed; from each stage, it will be taken out as the bottom of the tower, and the steam from each evaporation stage will be separated or together if appropriate to the next stage. Condensation. The condensate from the first stage is recycled to the extraction and the condensate from the subsequent stages is also recycled to the extraction or to one of the previous evaporation stages. Each individual evaporation stage can be made up by means of a distillation column. The smoke phase is processed via distillation. The distillation can be carried out batchwise or continuously. Priority vertebrae are given single or multiple levels of evaporation. The distilled hydrocarbons are recycled to extraction. Residues (which include cyclic and linear oligoethers) are discarded or fed to the re-dissociation place to become THF and copolymers, which can be reused in this procedure if applicable. Example PTHF having a cyclic oligoether (SFC) content of 0.5% by weight and a molar mass (Mn) of 825 g / h at 112 ° g / h at 50 ° C was used in a stirred "Ktihni," tower 19.1 g / h of n-heptane extraction. The -12-200303880 with 27 stirred tanks

⑻ The tower's nominal diameter is 60 milliyangs & eight ^ w penwood and the separation-active height is 1.1 meters. The diameter d of the agitator is 40 亳 m and the same degree h of the visualizer is 8 亳 m. The open part of the partition is 20% in the upper part ^ one knife & 30% in the rest of the tower. Stirring was performed at a rate of 150 l / min. Circumferential speed ^ is 〇31, and the u3 / h ratio is 3.9 m / s (the calculated maximum energy dissipation ε = 〇39 w / kg). The raffinate from the extraction, namely: the PTHF phase, contains approximately 41% by weight of dissolved heptane and 0.08% by weight of cyclic oligomer (SFC) residual content, equivalent to 0.14% by weight of 0 / 〇 in heptane-free PTHF. Unexpectedly, it was found that Liquid system polyTHF / n-heptane, droplets of polyTHF in alkanes and droplets of alkanes in polyTHF generally wet solid surfaces of metals, glass / ceramics and plastics. Wetting angles range from 0 ° Within the range of 40 °. A high degree of wetting usually reduces the mass transfer area in the tower and reduces the separation performance. Three theoretical extraction stages are achieved in the agitated tower; one theoretical separation stage is 3 in height 7 cm. Separation performance is equivalent to the value in a non-wetting system with a viscous dispersed phase. This shows that it is particularly suitable for agitating towers to extract cyclic oligoethers from PTHF or THF copolymers. Analysis of oligomers: SFC method n = 3-7: The determination is based on the internal standard method . In quantified based on == n cyclic oligomers having known proportions of the used reference materials 3-7 decanoic acid methyl ester as the internal standard " 13 -..

Claims (1)

200303880 Patent Park 1. A method for reducing the proportion of cyclic oligoethers in a copolymer of polytetrahydrofuran (PTHF) or tetrahydrofuran (THF), wherein the PTHF or THF copolymer is borrowed in one or more stages from 30 to 20 CTC Extraction from aliphatic, linear or branched or cycloaliphatic or olefinic hydrocarbons of 4 to 15 carbon atoms, mixtures of these hydrocarbons or mixtures of these hydrocarbons comprising at least 50% by weight, and PTHF or The THF copolymer phase and the hydrocarbon phase are separated from each other, in which the extraction is performed in a tower having a central agitator which extends through a plurality of agitating zones located one above the other, and the agitator has a cubic speed of three : The ratio of the height of the agitator exceeds 0.5 m2 / s3. 2. The method according to item 1 of the patent application, wherein the hydrocarbons of the PTHF or THF copolymer installed in the mixing device directly upstream of the column are fully or partially saturated. 3. The method of claim 2 in which the mixing device is a stirring vessel. 4. The method according to item 2 of the patent application, wherein the mixing device is a pipe mixer. 5. The method according to item 4 of the patent application, wherein the pipe mixer is a static mixer. 6. The method according to item 4 of the patent application, wherein the pipe mixer is a dynamic mixer. 7. The method according to item 6 of the patent application, wherein the dynamic pipeline mixer is a pump. 200303880 Lu, (a) (b) The designated representative of this case is: Di Li Brief description of the element representative symbols of this representative: 柒 If there is a chemical formula in this case, please disclose the chemical formula that can best show the characteristics of the invention: