DE102006009150A1 - Tetrahydrofuran polymers of viscosity suited to polyurethane (e.g. spinning solution) production is obtained by adding a linear aliphatic ether to the polymerization mixture - Google Patents

Abstract

A linear aliphatic ether is present at 0.001-5 wt.% in the reaction mixture when polytetrahydrofuran or a tetrahydrofuran (THF) copolymer is produced by polymerization of THF with an acid catalyst in presence of a telogen and/or a comonomer.

Description

object The present invention is a process for recovering polytetrahydrofuran or tetrahydrofuran copolymers having reduced functionality Polymerization of tetrahydrofuran - hereinafter called THF - in the presence of a Telogens and / or comonomers on an acid catalyst, wherein a content of linear aliphatic ethers of 0.001 to 5% by weight is adjusted in the reaction mixture.

Polytetrahydrofuran - in the following Called PTHF - that Also known as polyoxybutylene glycol, is in the plastic and synthetic fiber industry used as a versatile intermediate and is used, inter alia, for the production of polyurethane, polyester and polyamide elastomers. A particularly important application is the production of spandex fibers. It is beside it, as well some of its derivatives, a valuable one in many fields of application Excipient, for example as a dispersant or during decolorization (deinking) of waste paper.

PTHF becomes technically common by polymerization of tetrahydrofuran - hereinafter called THF for short - suitable Catalysts produced. By adding suitable reagents can the chain length the polymer chains are controlled and so the average molecular weight to the desired Value to be set. The control is done by choice of type and amount of telogen. Such reagents become chain termination reagents or "telogens" Choice of suitable telogens can additionally functional groups at one or both ends of the polymer chain introduced become. In industrial processes are often acetic anhydride or water as Telogens used.

Other Telogens not only act as chain termination reagents, but are also incorporated into the growing polymer chain of the PTHF. she not only have the function of a telogen, but are simultaneous a comonomer and therefore can with equal authority both as telogens and as comonomers be designated. examples for such comonomers are telogens with two hydroxy groups such as Diols (dialcohols). This can for example, ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,3-propanediol, 2-butyne-1,4-diol, 1,6-hexanediol or low molecular weight PTHF. Furthermore, as comonomers cyclic ethers such as 1,2-alkylene oxides, for example, ethylene oxide or propylene oxide, 2-methyltetrahydrofuran or 3-methyltetrahydrofuran. The use of such comonomers leads with Exception of water, 1,4-butanediol and low molecular weight PTHF for Preparation of tetrahydrofuran copolymers - hereinafter called THF copolymers - and makes it possible in this way to chemically modify PTHF.

For the catalytic conversion of THF with anhydrides, eg acetic anhydride, different acidic catalysts, such as acidic clays, acidic ion exchangers such as Nafion ^®, acidic metal or mixed oxides or heteropolyacids are known.

Particularly advantageous is the THF polymerization or THF copolymerization in the presence of C ₂ - to C ₁₂ carboxylic anhydrides or mixtures thereof with C ₂ - to C ₁₂ carboxylic acids such as acetic anhydride or acetic anhydride mixtures in the presence of acidic catalysts to mono- and or diesters of PTHF or THF copolymers and subsequent base-catalyzed transesterification of the PTHF esters or esters of THF copolymers with methanol to PTHF or THF copolymers (with terminal hydroxyl groups), as described for example in DE-A 10245198. As acidic polymerization catalysts, for example, acidic clays, acidic ion exchangers such as Nafion ^®, acidic metal or mixed oxides, or fluorosulfonic heteropolyacids contemplated.

In general, efforts are made to ensure the highest possible functionality of PTHFs. Functionality is understood as the so-called end-group functionality of the PTHF. If all ends of the PTHF molecules in the PTHF carry an OH group, the functionality is 2.000. A monofunctional alcohol such as n-butanol has the functionality of 1.000. In the reaction of PTHF with diisocyanates, the higher the functionality of the PTHF, the higher are the chain lengths. For certain applications, eg to improve the spinnability of the spinning solution in the process of spandex fiber production, however, it is desirable to make the degree of polymerization as low as possible in the reaction of PTHF with diisocyanates. To achieve this, it is known to add to the PTHF monofunctional alcohols such as n-butanol, as described in the published patent application JP-A 07-278 246. This also facilitates the control of the viscosity of the spinning solution (the polyurethaneurea polymer) for spandex fiber production. The exact incorporation of these monofunctional alcohols in the highly viscous polymer means a great deal of technical effort. In order to ensure the exact concentration of monofunctional alcohol in the PTHF, a separate tank with the appropriate dosing and mixing unit is usually necessary. Because of the high investment and operating costs, it is desirable to avoid the subsequent addition of monofunctional alcohols, which also reduces the risk of fluctuations in the n-butanol content in the PTHF due to the high volatility of the n-butanol, unkontrol The volatilized volatilization thereof and the resulting process fluctuations in the application of the corresponding PTHF advantageously reduced and provide a priori PTHF, which has a functionality less than 2.

For the direct Determination of functionality of the PTHF's From the prior art no method known. Therefore, the functionality of the PTHF's over the viscosity the spinning solutions made with this PTHF (e.g., polyurethaneurea or Polyurethane urea polymers in dimethylacetamide or in dimethylformamide) certainly. With otherwise the same recipe, concentration and method of preparation as well as the same process conditions and other starting materials correspond to lower viscosities the spinning solution a lower functionality of the PTHF.

It was therefore the task of a process for the preparation of PTHF or THF copolymers, with the simple and economical PTHF and copolymers of THF with certain functionality can be produced.

It has now become a process for the production of polytetrahydrofuran or tetrahydrofuran copolymers having a functionality of less two (2) by polymerization of tetrahydrofuran and in the presence at least one telogen and / or comonomer on an acidic catalyst found, the reaction mixture, via the return of unreacted THF and / or over the fresh feed to educts, 0.001 to 5 wt .-%, preferably 0.005 to 1 wt .-% based on the reaction mixture, a linear aliphatic Ethers be added.

Of the Feed to the reactor comprises tetrahydrofuran, telogen and / or Comonomer. The linear aliphatic ether may be one of the educts or the mixture thereof. Preferably, the THF contains or the THF / comonomer mixture the linear ether. The addition of the linear ether can in principle carried out in the fresh feed to the reactor or in the from the workup the polymerization recovered Return from THF and unreacted linear ether, which are preferred in the polymerization is returned.

For use in the method according to the invention are linear ethers derived from linear C1-C10 alcohols are such as Dimethyl ether, diethyl ether, methyl ethyl ether, dipropyl ether, methyl propyl ether, Ethyl propyl ether, dibutyl ether, methyl butyl ether, ethyl butyl ether, Propyl butyl ether, 4-hydroxybutyl-1-butyl ether, 4-hydroxybutyl-1-methyl ether, 4-acetoxybutyl-1-butyl ether suitable. Particular preference is given to diethyl ether, methyl butyl ether, 4-Acetyoxybuty-1-butyl ether.

To the new procedure leaves highly pure PTHF with the desired functionality produce safely and reproducibly.

Examples of the acidic heterogeneous or homogeneous catalysts used in the process according to the invention are described below:
In the production process according to the invention for PTHF and THF copolymers, a mono- and / or diester of the PTHF or of the THF copolymers is prepared in a first step by polymerization of THF preferably in the presence of acetic anhydride and optionally comonomers over acidic, preferably heterogeneous catalysts.

suitable Catalysts are, for example, catalysts based on bleaching earths as described for example in DE-A 1 226 560. Bleaching earth, especially activated montmorillonites can be used as shaped bodies in the Fixed bed or used in suspension.

Furthermore, catalysts based on mixed metal oxides, in particular groups 3, 4, 13 and 14 of the Periodic Table of the Elements, are known for the polymerization of THF. Thus, JP-A 04-306 228 describes the polymerization of THF in the presence of a carboxylic acid anhydride on a mixed metal oxide consisting of metal oxides of the formula M _x O _y with integer x and y in the range 1-3. Al ₂ O ₃ -SiO ₂ , SiO ₂ -TiO ₂ , SiO ₂ -ZrO ₂ and TiO ₂ -ZrO ₂ are mentioned as examples. Heteropolyacids, in particular H ₃ PW ₁₂ O ₄₀ and H ₃ PMo ₁₂ O ₄₀ can be used as catalysts on a support, but preferably unsupported.

The US 5,208,385 discloses catalysts based on amorphous silicon / aluminum mixed oxides. Mixed oxides based on SnO ₂ / SiO ₂ , Ga ₂ O ₃ / SiO ₂ , Fe ₂ O ₃ / SiO ₂ , In ₂ O ₃ / SiO ₂ , Ta ₂ O ₅ / SiO ₂ and HfO ₂ / SiO ₂ are also known. The aforementioned catalysts are preferably prepared by coprecipitation / sol-gel methods. Supported catalysts are disclosed in DE-A 44 33 606, where tungsten or molybdenum oxides on, for example, ZrO ₂ , TiO ₂ , HfO ₂ , Y ₂ O ₃ , Fe ₂ O ₃ , Al ₂ O ₃ , SnO ₂ , SiO ₂ or ZnO be applied. Furthermore, ZrO ₂ / SiO ₂ catalysts are recommended in which the carrier has an alkali metal concentration <5000 ppm.

All cited catalysts can used in principle as a fixed bed as well as suspension catalysts become.

Catalysts based on acidic ion exchangers are in US 4,120,903 for the polymerization of THF, in particular alpha-fluorosulfonic acid-containing polymers (for example Nafion ^® ), described in the presence of acetic anhydride. Farther For example, catalysts containing a metal and perfluoroalkyl sulfonic acid anions are suitable for THF polymerization.

In addition, other optionally activated clay minerals are known as polymerization catalysts, disclosed, for example, in WO 94/05719, WO 96/23833, WO 98/51729, WO 99/12992 and DE-A 195 134 93. Zeolites are also suitable as catalysts and are described for example in DE-A 43 16 138. Finally, sulfated zirconium oxides, sulfated aluminum oxides, supported heteropolyacids and supported ammonium bifluoride (NH ₄ F · HF) or antimony pentafluoride are also known as suitable polymerization catalysts. The process according to the invention is preferably carried out with activated bleaching earths.

Catalysts based on a tellurium compound and a BF ₃ or B (C ₆ F ₅ ) ₃ complex are mentioned in European Journal of Inorganic Chemistry 18 (2003), 3314-3317. Also, BF ₃ alone or with addition of water shows catalytic activity for the reaction. Likewise, other Lewis acid compounds, namely AlCl ₃ , SbCl ₅ or SnCl ₄ , also react. Likewise, salts with SbCl ₆ , AsF ₆ , SbF ₆ as a counter anion for the use of THF in the presence of concentrated sulfuric acid are suitable. The use of fuming sulfuric acid or of SO _{3 is also} described. Furthermore, concentrated sulfuric acid with a contact based on iron acetyl acetonate or the iron salt of an organic acid can be used.

Also (CF ₃ SO ₂ ) ₂ O, CF ₃ SO ₃ H, fluorosulfonic acid, chlorosulfonic acid and similar derivatives of sulfuric acid and also its salts, hydrogen fluoride, and perchloric acid are suitable as catalysts.

Becomes a solid catalyst used comes as a pretreatment of the catalyst for example drying with gases heated to 80 to 200 ° C., preferably to 100 to 180 ° C., such as. Air or nitrogen, in question.

The Polymerization is generally carried out at temperatures of 0 to 80 ° C, preferably from 25 ° C up to the boiling point of THF. The applied pressure is usually for the result of the polymerization is not critical, which is why in general at atmospheric pressure or operating under the autogenous pressure of the polymerization system.

to Preventing the formation of ether peroxides will cause the polymerization advantageously completed under an inert gas atmosphere. As inert gases can e.g. Nitrogen, carbon dioxide or the noble gases serve, is preferred Used nitrogen.

The Method can be operated batchwise or continuously, However, for economic reasons, it is preferably continuous operated.

Since telogens lead to chain termination, the mean molecular weight of the polymer to be produced can be controlled via the amount of telogen used. Suitable telogens are C ₂ - to C ₁₂ -carboxylic anhydrides and / or mixtures of protic acids with C ₂ - to C ₁₂ -carboxylic anhydride. The protic acids are preferably organic or inorganic acids which are soluble in the reaction system. Examples are C ₂ - to C ₁₂ -carboxylic acids such as acetic acid or sulfonic acids, sulfuric acid, hydrochloric acid, phosphoric acid. Preferably, acetic anhydride and / or acetic acid are used. In the first step of the polymerization, therefore, mono- and diesters of PTHF or THF copolymers are formed. When heteropolyacids are used as the polymerization catalyst, water is generally used as the telogen, so that the polymer formed has hydroxyl groups.

The Concentration of the acetic anhydride used as telogen in the polymerization reactor fed educt mixture (Feed) is in between 0.03 to 30 mol%, preferably 0.05 to 20 mol%, more preferably at 0.1 to 10 mol%, based on the THF used. If additionally acetic acid is used, so is the molar ratio in the Feed of the current polymerization usually 1: 20 to 1: 20000, based on the acetic anhydride used.

The Mono- and diesters of the THF copolymers can be prepared by the extra Use of cyclic ethers as comonomers, which polymerize in a ring-opening manner preferably three-, four- and five-membered rings, such as 1,2-alkylene oxides, e.g. Ethylene oxide or propylene oxide, oxetane, substituted oxetanes, such as 3,3-dimethyloxetane, the THF derivatives 2-methyltetrahydrofuran or 3-methyltetrahydrofuran, with 2-methyltetrahydrofuran or 3-Methyltetrahydrofuran are particularly preferred.

Likewise, the use of C ₂ - to C ₁₂ -diols as comonomers is possible. These may be, for example, ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,3-propanediol, 2-butyne-1,4-diol, 1,6-hexanediol or low molecular weight PTHF. Further suitable comonomers are cyclic ethers, such as 1,2-alkylene oxides, for example ethylene oxide or propylene oxide, 2-methyltetrahydrofuran or 3-methyltetrahydrofuran.

Depending on the telogen content of the polymerization mixture, the process can be used to prepare mono- and / or diesters of PTHF or THF copolymers selectively produce with average molecular weights of 250 to 10,000 daltons, preferably the relevant PTHF esters having average molecular weights of 500 to 5000 daltons, particularly preferably 650 to 4000 daltons are prepared by the process according to the invention. In this application, the term "average molecular weight" or "average molecular weight" is understood to mean the number average M _{n of} the molecular weight of the polymers, the determination of which is carried out, for example, by wet-chemical OH number determination.

If a solid polymerization catalyst is used, the THF-containing Discharge from the polymerization stage filtered to traces of the polymerization catalyst withhold and then fed to the distillative THF separation. It however, TNF can be separated first and then the remaining ones Mono or diester of PTHFs of catalyst residues freed by filtration become. The second method is considered preferred. As filter devices become industrially conventional layer filters used.

The Ester groups in the polymers thus obtained must in a second step being transformed. A usual Method provides the reaction initiated by alkaline catalysts with lower alcohols. The transesterification with alkaline catalysts is known from the prior art and, for example, in DE-A 101 20 801 and DE-A 197 42 342 described. Preference is given to methanol as lower alcohol and as effective transesterification sodium methylate used.

The obtained polymers can by reaction with organic isocyanates in per se known Way of polyurethane and polyurethane urea production in particular for the production of thermoplastic urethanes, spandex, thermoplastic Ether esters or Copolyetheramiden be used. object The present invention therefore further the use of the according to the inventive method prepared polytetrahydrofuran or the tetrahydrofuran copolymers for the production of polyurethane polymers or polyurethane urea polymers, as for example for the production of elastic fibers, also Spandex or Elasthan called, thermoplastic polyurethane (TPU) or from Polyurethane cast elastomers (Cast elastomers) are needed.

there is in a conventional manner PTHF or a THF copolymer first with an organic diisocyanate in excess and then with a implemented organic diamine as described for example in JP-A 07-278 246.

The The invention will be explained in more detail below with reference to examples.

Examples

example 1

Preparation of a spinning solution (polyurethane polymer)

PTHF prepared according to the following inventive examples 2 and 3, or According to Comparative Example 1, with 4,4 'diphenylmethane diisocyanate in a molar ratio 1: 1.62 mixed and heated in a glass flask to 90 ° C. After 45 minutes was the resulting prepolymer at 30 ° C chilled and with so much N, N dimethylacetamide (DMAC) added that one 45% strength by weight solution originated (solution A)). For chain extension became a 1.9% by weight solution a mixture of ethylenediamine (EDA), 1,2-propylenediamine (PDA) and diethylamine (DEA) in DMAC. The molar ratio of EDA: PDA: DEA was 4: 1: 1 (solution B). 96 g of the solution A were at 30 ° C were submitted within 30 minutes with stirring 40th g of the solution B added. The viscosity the resulting spinning solution was at 40 ° C with a Haake VT550 SV 2. viscometer (Millipaskal · second = mPas).

Example 2

19.8 g / h THF and 3.4 g / h acetic anhydride were continuously over 200 in a fixed bed reactor at 40 ° C mL of an acid-activated, dislocated montmorillonite catalyst as described in DE-A 10245198, Example 3 is described, passed. The feed stream to the reactor 0.2 g / h (0.85% by weight) of n-butyl methyl ether was added. The reaction mixture was continuously pumped into the reaction apparatus by a pump guided in a circle through the reactor, with a constant circulation: feed ratio of 50: 1 complied has been. In each hour, 23.4 g of fresh feed was added to the reactor registered while the same amount of reaction product was removed from the circulation. For analysis, the volatile Proportions of the reaction output, essentially THF and acetic anhydride and unreacted linear ether, in vacuo at 70 ° C / 30 mbar, then at 170 ° C / 3 evaporated mbar. The polymeric residue was transesterified with methanol and sodium methylate to the diol, the Sodium ions by precipitation with phosphoric acid and subsequently Filtration removed. By distillation via a short path distillation at 1 mbar / 200 ° C the PTHF was freed from lower oligomers. The molecular weight of the thus obtained product was 2055 mol / g. The like from the so obtained PTHF by further reaction as described in Example 1 ultimately resulting polymer solution in DMAC had a viscosity of 63900 mPas at 40 ° C.

Example 3

As in Example 2, THF was polymerized in the presence of acetic anhydride, However, the feed stream to the reactor 4.3 wt .-% diethyl ether added. This according to the example 2 described PTHF had a molecular weight of 2036 g / mol. After conversion to the spinning solution according to Example 1 became a viscosity the spinning solution measured from 37500 mPas.

Comparative Example 1

As Example 2 described 20 g / h of THF and 3.4 g / h of acetic anhydride in a fixed bed reactor at 40 ° C continuously over 200 mL of an acid-activated, dislocated montmorillonite catalyst as described in DE-A 10245198, Example 3 is described. In contrast to the examples according to the invention the feed to the reactor was free of linear ethers the procedure of Example 2, the reaction mixture was a pump continuously in the reaction apparatus in a circle through led the reactor, with a constant circulation: feed ratio of 50: 1 was maintained. In each hour, a further 23.4 g of the reaction mixture in the Reactor registered while the same amount of reaction product was removed from the circulation. For analysis, the volatile Portions of the reaction effluent, i. essentially unreacted THF and acetic anhydride, in a vacuum at first 70 ° C / 30 mbar, then at 170 ° C / 0.3 evaporated mbar.

Of the polymeric residue was transesterified with methanol and sodium methylate to the diol, the sodium ions by precipitation with phosphoric acid and subsequently Filtration removed. By distillation via a short path distillation at 1 mbar / 200 ° C the PTHF was freed from lower oligomers. The molecular weight of the thus obtained PTHF's was 2024 mol / g.

The Product was reacted as described in Example 1 to a spinning solution. The viscosity the spinning solution at 40 ° C was 90300 mPas.

Claims (8)

A process for the preparation of polytetrahydrofuran or tetrahydrofuran copolymers by polymerization of tetrahydrofuran, in the presence of a telogen and / or a comonomer on an acidic catalyst, characterized in that the reaction mixture contains from 0.001 to 5 wt .-% of at least one linear aliphatic ether. Method according to claim 1, characterized in that the content of linear ether is between 0.005 and 1%. Method according to claim 1 or 2, characterized that the tetrahydrofuran or tetrahydrofuran / comonomer mixture used for the polymerization is the linear Contains ether. Method according to one of claims 1 to 3, characterized that the catalyst is selected is from bleaching earth, mixed metal oxides of groups 3, 4, 13 and 14 of the Periodic Table of Elements, supported tungsten or molybdenum oxides, heteropolyacids acidic ion exchangers, zeolites sulfated zirconium oxides and / or strong mineral acids Method according to one of claims 1 to 4, characterized that the linear ether is dimethyl ether, methyl ethyl ether, Dipropyl ethers, methyl propyl ethers, ethyl propyl ethers, dibutyl ethers, Methyl butyl ether, ethyl butyl ether, propyl butyl ether, 4-hydroxybutyl-1-butyl ether, 4-acetoxybutyl-1-butyl ether, 4-hydroxybutyl-1-methyl ether or their Mixtures are. Method according to one of claims 1 to 5, characterized that the linear ether is diethyl ether, methyl butyl ether and / or 4-acetoxybutyl-1-butyl ether is. Use of the method according to any one of claims 1 to 6 prepared polytetrahydrofuran or tetrahydrofuran copolymers for the production of polyurethaneurea polymers. Use according to claim 7, characterized that according to one of the claims 1 to 6 produced Polytetrayhydrofuran or tetrahydrofuran copolymer for the preparation of thermoplastic polyurethanes, spandex, thermoplastic ether esters or copolyetheramides is used.