TW200303881A - Preparation of polytetrahydrofuran having a reduced content of oligomeric cyclic ethers - Google Patents

Abstract

The present invention relates to a process for preparing polytetrahydrofuran or tetrahydrofuran copolymers having a mean molecular weight of from 650 to 6000 and a content of cyclic oligomeric ethers of less than 1% by weight by solvent treatment, which comprises a) extracting PTHF or THF copolymers at from 20 to 120 DEG C with an aliphatic, linear or branched or cycloaliphatic or olefinic hydrocarbon having from 1 to 15 carbon atoms, a mixture of such hydrocarbons or a mixture comprising at least 50% by weight of such hydrocarbons in one or more stages, b) separating the PTHF or THF copolymer phase and the hydrocarbon phase from one another, c) substantially freeing the PTHF or THF copolymer phase of hydrocarbon, d) separating the hydrocarbons by distillation from the hydrocarbon phase obtained in step b), and e) redissociating the mixture of cyclic oligomeric ethers and linear PTHF oligomers or oligomeric THF copolymers obtained in step d) over catalysts to give THF and, if desired, recirculating THF to the polymerization.

Description

(2) (2) 200303881 (1) Description of the invention (The description of the invention shall state: the technical field to which the invention belongs, the prior art, the content, the embodiments, and the simple description of the drawings) the technical field; Method for polytetrahydrocran or tetrahydrocran copolymer with low cyclic culture λκ test content from 650 to 6000. Polytetrahydrofuran of the prior art, hereinafter referred to as pTHF, which is also known as polybutylene oxide, is used as a multipurpose intermediate in the plastics and synthetic fiber industry, and especially for the preparation of polyurethane elastomers, polyesters Elastomers and polyamide elastomers are also 'similar to some of their derivatives, which are valuable aids in many applications (for example as dispersants) or deinking of waste paper. PTHF is generally manufactured industrially by polymerization of tetrahydrofuran (hereinafter abbreviated as thf) on a suitable catalyst. The addition of a suitable reagent allows the chain length of the polymer chain to be controlled and therefore allows the average molecular weight to be set to a desired value. Such agents are known as chain terminators or regulators. "Control can be achieved through the choice of the type and amount of the withdrawing agent. The selection of a suitable regulator allows additional functional groups to be added at one end of the polymer chain or Both ends are introduced. In this way, for example, using monoacid or diacid anhydride as a regulator, PTHF can be prepared as mono- or di-g, which must then be converted to PTHF by saponification or g-group transfer. So this method It is called the two-stage 1 > 1 ^ 1? Method. Other modifiers are not only used as chain terminators, but also incorporated into pTHF's growing spout chain. They not only have the function of regulators but are also comonomers and therefore They may be referred to as regulators or comonomers equally. Examples of such comonomers are regulators with two hydroxyl groups, such as diols (diacolls). They can be, for example, ethylene glycol, propylene glycol, butanediol, 3-propanediol, ^ (3) (3) 200303881

Butanediol, butyne-1,4 · diol, 1,6-hexanediol, or low molecular weight ρτ ^^ Other suitable comonomers are cyclic ethers such as 1,2-fluorene oxides, such as ring gas-1 Or propylene oxide, 2-methyltetrahydrofuran or fluorene methyltetrahydrofuran. 2 Hexaσ The use of such j ± monomers (except water, butanediol, and low-molecular-weight pTHF) results in the preparation of furan copolymers (hereinafter referred to as THF copolymers), and PTHF is improved in this way. . The chemical industrial preparation is mainly carried out by a two-stage process, in which, for example, a four gas port is polymerized in the presence of fluorosulfonic acid to form polytetrahydrofuran esters and the latter == is hydrolyzed to polytetrahydrofuran. Alternatively, if tetrahydrofuran is present in the presence of an acidic catalyst ^ polymerized with acetic anhydride to form polytetrahydrofuran diacetate and then transesterified with methanol to obtain polytetrahydrofuran, such as European Patent-A 38 009 and German Patent · A 28 0 1 578. The single-stage synthesis of PTHF has been known from WO 96/039355 and was carried out on an acidic catalyst with the polymerization of THF using water, 1, butanediol or low molecular weight hitachi as a regulator. Known catalysts include systems that dissolve uniformly in the reaction system and are non-uniform (i.e., large stings do not resolve), such as heteropolyacids already known from European patents and those known from US patents and 4 128093. Super acid Nafion (R) ion exchange resin. German patent-A 44 33 ϋ 丨 丨 4 private, especially 疋 describes a kind of conditioner water, 1,4-butanediol, and ram

The method of preparing PTHF by polymerizing tetrahydrofuran in the presence of a mixture of pthF of 200 to 700 Daltons in the knife or one of the two inscriptions, Japan / v W, and M, is now The catalyst is a carrier catalyst, which includes the catalytic activity of an antacid or molybdenum compound or a mixture of these compounds on a oxidized carrier material. Oxygen-containing tungsten or molybdenum compound 200303881

(4) After the precursor compound, it is fired from 500 ° C to 1000 ° C. German Patent-A 196 49 803 discloses that the catalyst activity described in German Patent A 44 33 606 is increased by a co-catalyst. U.S. Patent-A 5 149 862 describes sulfate-doped zirconia as a heterogeneous acid catalyst for the polymerization of tetrahydrofuran. A considerable proportion of low-molecular-weight products are formed in the above-mentioned and other methods of tetrahydroanthran polymerization or copolymerization. These unwanted by-products include or consist of oligomeric cyclic ethers, they can be present in proportions of up to 20% by weight, and the proportion formed in the two-stage process of polymerization or copolymerization is smaller than in a single stage. These oligomeric cyclic ethers are undesirable for several reasons. As inert compounds, they involve further methods of polymers, for example they react with isocyanates to form polyurethanes, they are used as plasticizers and generally have a negative effect on the mechanical properties of the finished product. The surface of the finished product oozes or can be filtered out by a solvent, for example, it has a negative effect on the shape stability of the finished object. Therefore, many attempts have been made to reduce the content of oligomeric cyclic ethers in tetrahydroan polymers or copolymers. German patent 35 14 547 discloses the extraction of oligocyclic ethers from PTHF and THF copolymers by a mixture of water and hydrocarbons, and the polymer is recovered from the aqueous phase. U.S. Patent No. 3,478,109 discloses a method for removing low molecular weight portions from polytetrahydrofuran or a tetrahydrofuran copolymer in which a hydrocarbon solution of the polymer is extracted with a methanol / water mixture. European Patent 153 794 describes a method for reducing the content of oligomeric cyclic ethers in polytetrahydrool and tetrahydrocollane copolymers, in which cyclic ethers are synthesized by hydrocarbons (5) 200303881

From 20 to 60 ° C from crude, the residual amount of cyclic oligoethers in the prior art method is still to the extent that the THF copolymer does not comply with the invention. ^ Tetrahydrofuran and tetrahydrofuran copolymer extraction. The point is that even after repeating the method, it remains quite high in the polymer. Requirements for the obtained PTHF or the obtained degree of distribution and chromaticity. Because cyclic oligoethers involve a further method of% hydrogen squeegee or tetrahydrofuran copolymers, such as by acting as a plasticizer or having a negative effect on the mechanical properties of the finished product, the purpose of the present invention is to discover the production of polytetrahydrofuran Or a method of a tetrahydrofuran copolymer 'which can reduce the proportion of oligomeric cyclic ether of the following formula in a simple and economically advantageous manner [0-CH2-CH2] II [CH2-CH20] m [CH2-CH2-O] 2 [OCH2-CH2 -CH2- * CH2] m [(DCH2 -CH2 -CH2 -CH2]

I I

[CH2-CH2-CH2-CH2〇] m (where n = 1, 2 or 3 and m = 2, 3, 4, 5, 6, 7 or 8) to less than 1 weight percent (based on polytetrahydrofuran or tetrahydrofuran) Copolymer). And 'this method makes it possible to have a molecular weight from 600 to 6000, a degree of polymerization distribution from 1.5 to 2.5, preferably from 15 to 23, and a chroma of less than 40 aphA, preferably less than 20 Eighteen eighteen? Butylene or copolymers are manufactured. Embodiments We have found that these purposes can be used to prepare polytetrahydrobites with average molecular weight from 650 to 6000 and cyclic polyether content of less than 1% by weight through solvent treatment. -10- 200303881

(6) A method of sulfan or tetrahydrofuran copolymer comprising: a) a linear or branched aliphatic or cycloaliphatic or fumes-based hydrocarbon having from 4 to 15 carbon atoms, such a hydrocarbon Mixtures of compounds, or mixtures containing at least 50% by weight of such hydrocarbons, range from 20 to 120 in one or more stages. (: Extracting the PTHF or THF copolymer, b) separating the PTHF or THF copolymer phase and the hydrocarbon phase,

C) fully release the hydrogen-barrier compounds of the PTHF or THF copolymer phase, d) separate the hydrocarbons 5 and e by distillation from the hydrocarbon phase obtained in step b) and dissociate on the catalyst in step d) A mixture of the obtained cyclic oligoether and linear PTHF oligomer or oligomeric THF copolymer to obtain THF and, if necessary, recycle THF to the polymerization reaction.

The PTHF or THF copolymer to be treated is prepared in a single stage known per se in the presence of a strong acid catalyst or in two stages via PTHF esters, which are then hydrolyzed and transesterified. PTHF can be prepared, for example, by a single-stage method described in German Patent-A 44 33 606 or WO 96/9335 and generally contains from 0.5 to 10% by weight of cyclic oligomeric ethers. THF copolymers with it olefin oxides such as ethylene oxide can also be obtained from the methods described in GB-B-854 958 and German Patent-B-3 346 Π4 and generally contain oligomerization from 1 to 20% by weight Cyclic ether. Selective removal of cyclic oligomers from PTHF or THF copolymers in step a) can be used according to the invention with from 4 to 15 carbon atoms, preferably from 7 to ii carbon atoms, particularly preferably 9 It is achieved by extraction of aliphatic, cycloaliphatic or dilute smoke hydrocarbons of one carbon atom or a mixture of such hydrocarbons or a mixture of such hydrocarbons containing at least 50% by weight of -11-200303881 ⑺. Suitable hydrocarbons for use in the extraction step a) include saturated and unsaturated aliphatic and cycloaliphatic compounds and olefinic compounds, each of which may have a substituent such as a tooth atom or an oxyalkyl group, preferably a saturated and unsaturated , Branched and straight chain aliphatic chlorocarbons, any mixture of chlorocarbons can also be used. By way of example, the following carbon and nitrogen compounds: saturated aliphatic and cycloaliphatic nitrogen-breaking compounds such as sintered with 4 to 15 atomic hindrances such as butanol, pentyl and decyl, and branched chain compounds such as 2. Roasting and isomerization of 'Cyclolipids with 5 to 12 carbon atoms such as cyclopentan, m-hexane, cyclooctane and cyclodecane, unsaturated aliphatic or cycloaliphatic hydrocarbons such as from 4 to Twelve carbon atoms such as isobutylene and cyclohexene. The preferred solvent is a saturated hydrogenated compound having from 4 to 15 carbon atoms. Particularly preferred are hydrocarbons having from 7 to 丨 carbon atoms, and most preferably 9 carbon atoms. The amount of hydrocarbons or hydrocarbon mixtures used for extraction can be varied over a wide range. Generally, the weight ratio of hydrocarbons to ρτΗρ or thf copolymer is at least 0.5: 1. In particular, its range from 15: 1 to 5: 1 in the range from 1: 1 to 10: 1. Extraction is generally carried out from 20 to 120 ° C, preferably from 40 to 100 t :, particularly preferably from 50 to 80 t :. The pressure depends on the vapor pressure of the solvent at the selected extraction temperature, preferably extraction at atmospheric pressure. Liquid / liquid stroke is performed in a conventional manner in one or more stages, typically up to five stages. Appropriate devices and operating procedures are known and described by those skilled in the art, for example, in "Ullmann, S EnCydopediaf 6-6, Electronic Release". Batch extraction can be carried out in a stirred container -12- 200303881

⑻ OK. Examples of continuous extraction are sieve tray columns, stirrer columns and extractor groups such as mixer-settler. Thin-film extraction towers such as hollow fiber modules can also be used. In this extraction, the content of cyclic oligoether can be reduced to less than 1% by weight based on PTHF. After extraction, the cyclic oligoether-containing hydrogen-blocking compound phase and a small amount of linear PTHF oligomers (less than 2% by weight based on pthF or THF copolymer) were separated from the PTHF or THF copolymer phase by phase separation. In step c), the PTHF or THF copolymer phase is again released by distillation of most of the hydrocarbons remaining in it, that is, reduced to from 0.01 to 1% by weight (based on PTHF), preferably It is reduced to a content of from 0.05 to 0.5% by weight. Suitable devices and procedures are known and described by those skilled in the art, such as in "Ullmann, s Encyclopedia of Industrial Chemistry, 6th Edition, Electronic Release". Distillation can be carried out batchwise or continuously, preferably single-stage or multi-stage evaporation, in which purified THF is taken from the bottom of each stage and sent to the next stage if appropriate. The vapors from the evaporation stage are condensed separately or together, and the condensate from the evaporation stage is preferably recycled to extraction. However, individual condensates can be recycled to the previous evaporation stage. There can be one distillation column for each winding stage. The first stage of the distillation is carried out at a pressure ranging from 0.1 to 10 bar (preferably atmospheric pressure) and the subsequent stage is from 0.00 1 to 0.1 bar (preferably 0.01 bar). The single-stage evaporation is carried out from 0.01 to 1 bar (preferably 0.05 bar). The temperature depends on the boiling point of the hydrocarbon or hydrocarbon mixture, and is generally in the range from 100 to 301, and preferably from 180 to 220. (:. The cyclic oligomers with molecular weights from 650,000 to 6,000 WPthf or copolymers obtained in this way are less than!% By weight (based on thirteen or thf total -13- 200303881

(9) Polymer), the degree of distribution of polymerization is from 15 to 25, and the color is less than 40APHA. If a particularly low degree of polymerization distribution is required, such as from 15 to 丨 · 8, it is more advantageous to separate the residual amount of the lower oligomer 'extract from the obtained PTHF by further distillation, which is also advantageously removed here. This distillation can be performed at, for example, from 200 to 250 C and pressure from 0 to 10 mbar, preferably from 0.5 to 5 mbar. In step d) 'the cyclic oligoether is separated from the hydrocarbon phase by distillation. Appropriate equipment and operating procedures are known and described by those skilled in the art, such as in Ullmann s Encyclopedia 〇f industrial Chemistry, 6th Edition, Electronic

Release ". The steaming hall can be carried out in a continuous or continuous manner, preferably in a single stage or multiple PI's, where the oligomer to be concentrated is taken out from each stage as the bottom product and if appropriate, it is sent to the next one. Stage. The vapors from the evaporation stage are condensed separately or together. The condensate from the stage is preferably recycled to extraction. However, the 'condensate can also be recycled to the previous evaporation stage. Each evaporation stage can have a distillation column. One stage is performed at a pressure ranging from 0.1 to 10 bar (preferably atmospheric pressure) and the subsequent stage (if applicable) is from 0.001 to 0.1 bar (preferably 0.001 bar). Single The stage evaporation is carried out at from 0.01 to 1 bar, preferably at 0 2 bar. The temperature depends on the boiling point of the solvent or solvent mixture, and is generally in the range from 100 to 300, preferably 2 in steps. d) The mixture of the obtained cyclic oligoether, linear PTHF oligomer and linear-polyTHF copolymer can be dissociated from outside to Τρρ such as aluminosilicate, as described in German patent _a_441〇685 .J THF obtained in this way can be recycled THF is used as the polymerization or U, he uses -14--. 200303881

⑽ If the lower nutrients have been separated from ρ τ H F obtained in step c) by distillation, the lower aggregates obtained can be combined with the oligomer mixture obtained in step d) (Figure 1). All the mentioned steps can be carried out batchwise, but preferably continuously. It cannot be expected that the combination of methods provided by the present invention results in PTHF with a cyclic oligomer content of less than 1% by weight (based on PTHF or THF copolymer), a degree of polymerization distribution from 1.5 to 2.5 ', and a chromaticity of less than 40 APHA or THF copolymer

The high yields are feasible and therefore surprising.

In addition, 'the amount of PTHF (ie, linear polymer) that can be extracted under the conditions according to the present invention cannot be expected. From an economic point of view, this amount is important because of the size of the plant and the dissociation of the pTHF oligomer into THF. The energy required increases with the amount of oligomer. Example 1 surprisingly confirmed that about 2% of linear PTHF was extracted. Moreover, according to the invention, even less than 2% of the linear PthF is dissolved and extracted in n-nonane. Moreover, in the case of very long long-chain hydrocarbons, it was found that the solvent content in the product P T H F is reduced, which significantly reduces energy and equipment costs in distillation. Examples The present invention is illustrated below with examples and drawings. The molecular weight determines the average molecular weight (Μη) of the obtained PTHF by colloidal filtration chromatography (GPC) and is defined by the following equation: Mn = ZCi / Z (Ci / Mi) and the weight average Mw is defined by the following equation: Mw = (I (Ci * Mi) / I Ci > -15-200303881

⑼ where Ci is the concentration of individual polymer i in the resulting polymer mixture (expressed as% by weight) and Mi is the molecular weight of individual polymer i. The degree of polymerization distribution D is used as a measure of the molecular weight distribution of the polymers prepared in the examples and is calculated from the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) according to the following formula D = MW / Mn

Mw & Mn was determined by colloidal filtration chromatography (GPC) using standard PTHF as a calibration. Superfluid chromatophoresis is described by, for example, K. Anton et al. In Tomography Science Vol. 32, October 1994, pages 430-437. Decisions are made by internal standard methods. Quantitation is based on a reference material with a known ratio of cyclic oligomers, and methyl caprate is used as an internal standard. The contents shown below are based on the PTHF solution and the values are the unrounded averages of two injections in a single test portion.

Determination of the number of OH The number of hydroxyl groups is the milligram amount of potassium hydroxide, which is equivalent to the amount of acetic acid linked when 1 g of the substance is tritiated. The number of hydroxyl groups is determined by the esterification of hydroxyl groups in the presence of excess acetic anhydride. After the reaction, the excess acetic anhydride is hydrolyzed with water according to the following reaction formula and titrated back to acetic acid using sodium hydroxide. Example 1 5 04.5 grams of cyclic oligopolyether content 2.5% by weight (8? (:), molecular mass (Mn) 204 0 (OH number: 55 mg KOH / g) and the degree of polymerization distribution of 2.5-5 -16 -(12) 200303881

PTHF at 50. (: And 1.3 times the amount of n-heptyl ^ ^ ^ ^ 黡 pits were blended in a stirring container. The mixture was stirred vigorously for 15 minutes, then precipitated, and the phases were separated. The resulting PTHF phase was 1.3 times the amount as described. The n-heptane was re-extracted a total of five times with PTHF. This time, the heptane dissolved in PTHF was treated at a single > Eph point 1 8 3 C and then at 500 bar; [9 4 ° C steamed to 0. 1% by weight. In order to remove low molecular weight PTHf, mbar was subjected to bulb distillation. Stage batch distillation was performed before 200 mbar to distill off. The residual heptane extract was found at 180 ° C and 1 knife analysis. PTHF has an average molecular weight distribution degree β of 2.1, a cyclic oligoether content of 0 ″% by weight, and a color of 18 ApHA. 2 22 grams of this first n-heptane extract was preceded by a single-stage batch distillation. 220¾ bar to a boiling point of 70 t, followed by boiling at 20 mbar and 7 (Γ (: and finally boiled at Yuzhaiba and room temperature to an oligomer, that is, no longer heptane is detected. Residue The analysis shows that the content of cyclic oligoether is 1% by weight and the concentration of PTHF is 2.2% by weight, both based on the amount of extract. From this, 57% (extraction degree) of cyclic polyether is calculated 2.9% of PTHF is extracted in the first extraction step, which corresponds to a selectivity of 20, based on the extraction degree ratio.

Figure 1 shows a flowchart of the method of the present invention. -17-

Claims (1)

200303881 Pick up and apply for patent scope 1. A method for preparing polytetrahydrofuran or tetrahydrofuran copolymer by solvent treatment, which has an average molecular weight from 650 to 6000 and a cyclic oligopolyether content of less than 1% by weight. This method includes a) to Linear or branched aliphatic or cycloaliphatic or olefinic hydrocarbons or mixtures of such hydrocarbons or mixtures containing at least 50% by weight of such hydrocarbons having from 1 to 15 carbon atoms Extract the PTHF or THF copolymer from 20 to 120 ° C in one or more stages, b) separate the PTHF or THF copolymer phase and the hydrocarbon phase, C) fully release the PTHF or THF copolymer phase Hydrocarbons, d) separating the hydrocarbons from the hydrocarbon phase obtained in step b) by distillation, and e) dissociating the cyclic oligoethers obtained in step d) and linear PTHF on the contact butterfly Or oligomeric THF copolymer to obtain THF and, if necessary, recycle THF to polymerization. 2. The method according to item 1 of the patent application scope, wherein a hydrocarbon having from 7 to 11 carbon atoms + is used. 3. The method according to item 1 or 2 of the applied patent, wherein the extraction is performed from 20 to 120 ° C. 4 The method according to item 1 or 2 of the scope of patent application, wherein the carbon gas compound separated in step C) is recycled to step a). 5. The method according to item 1 or 2 of the patent application scope, wherein the gaseous compound separated in step d) is recycled to step a).