GB1575529A - Polytetramethylene ether glycol esters - Google Patents

Description

(54) POLYTETRAMETHThENE ETHER GLYCOL ESTERS (71) We, E. I. DU PONT DE NEMOURS AND COMPANY, a corporation organized and existing under the laws of the State of Delaware, located at Wilmington, State of Delaware, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- Poly(tetramethylene ether) glycol (PTMEG) is a commodity in the chemical industry, widely used in the manufacture of polyurethanes and polyesters. it is commonly prepared by reacting tetrahydrofuran (THF) with fluorosulfonic acid and then quenching the product with water.

While this process has proved to be quite satisfactory, it is not as efficient as desired because the acid cannot be recovered and reused. Moreover, disposal of the spent acid is a problem because of its toxicity and corrosiveness.

It has now been found that esters of PTMEG can be prepared by polymerizing THF in a reaction mixture which contains THF, an acylium ion precursor and a catalyst for the polymerization reaction which, although more complex than that, can for purposes of summary be described as a polymer containing alpha-fluorosulfonic acid groups. These esters can then be converted to PTMEG by alcoholysis in a basic medium, using an oxide, hydroxide or alkoxide of calcium, strontium, barium or magnesium as a catalyst.

In the first portion of the process, the nature of the catalyst permits its reuse, thereby eliminating the disposal problem, and the catalyst's low solubility in the reaction mass makes it easy to separate the product from the catalyst at the end of the reaction. This low solubility also minimizes loss of catalyst as the reaction proceeds.

The invention comprises first bringing together, under conditions suitable for polymerization, the THF reactant, an acylium ion precursor, the catalyst and optionally a carboxylic acid.

The polymerization is believed to involve the steps of initiation, propagation, chain transfer, redistribution, terwination and catalyst regeneration. These steps occur simultaneously, in a competing manner, and are thought to proceed as shown in the following illustrative equations: Initiation

catalyst acylium ion precursor

acyl oxonium ion Propagation

Chain TransFer

Redistribution

Termination

Catalyst Regeneration

In these equations, R' in hydrogen or a hydrocarbon radical, e.g. having 1--36 carbon atoms, NfSO3H represents the catalyst and represents the poly(tetramethylene ether) chain.

When the reactions are complete, the catalyst can be separated from the reaction mass and reused.

The THF used as the reactant can be any of those commercially available. It preferably has a water content of less than about 0.001%, by weight, and a peroxide content of less than 0.002%, by weight, and preferably contains an oxidation inhibitor such as butylated hydroxytoluene to prevent formation of undesirable byproducts and color.

If desired, 0.1 to 50% by weight of the TMF of an alkyl tetrahydrofuran, copolymerizable with THF, can be used as a coreactant. Such an alkyl THF can be represented by the structure.

where any one of R1, R2, R3 or R4 is an alkyl radical of 1 to 4 carbon atoms, the remaining R's being hydrogen.

Illustrative of such alkyl tetrahydrofurans are 2-methyltetrahydrofuran and 3 methyltetrahydrofuran.

The catalysts used are polymers of ethylenically unsaturated monomers containing groups of the formula

where represents the polymer chain or a segment thereof; D is hydrogen, an aliphatic or aromatic hydrocarbon radical of I to 10 carbon atoms, a halogen atom or a segment of the polymer chain; X and Y are hydrogen, halogen, or an aliphatic or aromatic hydrocarbon radical of 1 to 10 carbon atoms, at least one being fluorine; R is a linear or branched linking group having up to 40 carbon atoms in the principal chain, and Z is hydrogen, halogen, or an aliphatic or aromatic hydrocarbon radical of 1 to 10 carbon atoms.

The linking group defined by R in formula (9) can be a homogeneous one such as an alkylene radical, or it can be a heterogeneous one such as an alkylene ether radical. In the preferred catalysts, this linking radical contains 1 to 20 carbon atoms in the principal chain. In the especially preferred catalyst, R is a radical of the structure

The catalysts of formulas (7) and (8) have equivalent weights of 950 to 1,500, preferably 1,100 to 1,300. Equivalent weight of a catalyst is that weight in grams which contains one gram equivalent weight of sulfonic acid groups, and can be determined by titration.

Illustrative of the ethylenically unsaturated monomers which can be used to prepare these polymer chains are ethylene, styrene, vinyl chloride, vinyl fluoride, vinylidene fluoride, chlorotrifluoroethylene (CTFE), bromotrifluoroethylene, vinyl ethers, perfluoroalkyl vinyl ethers, butadiene, tetrafluoroethylene, hexafluoropropylene and combinations of these The -SO3M groups are introduced into the catalyst polymer chain by copolymerizing these ethylenically unsaturated monomers with such ethylenically unsaturated monomers as trifluorovinyl sulfonic acid, linear or branched chain vinyl monomers containing sulfonic acid group precursors or perfluoroalkylvinyl ethers containing sulfonic acid group precursors. This can be done according to the procedures described in U.S. Patent 3,784,399 to Grot, and the patents cited therein. Monomer ratios are selected to give the resulting polymer the proper equivalent weight.

The catalyst preferably has a solubility such that no more than about 5%, by weight, dissolves in the reaction mass at the reaction temperature (preferably 22v5 C, see below) when the reaction is run in a batch mode for a time to be specified hereinafter. This solubility is determined gravimetrically.

It is desirable that the solubility of the catalyst be as low as possible because this minimizes catalyst loss and permits the process to be run for longer periods without catalyst replenishment. Preferably, the solubility is no more than 1%, by weight, and even more preferably is below the threshold of detection with present analytical techniques.

The catalyst should be effectively free of functional groups, other than -SO3M groups, which might interfere with the polymerization reaction, "Effectively free" means the catalyst may contain a small number of such groups, but not so many that the reaction is affected adversely or the product contaminated. Illustrative of such groups are carboxyl groups, hydroxyl groups and amino groups.

Catalysts whose polymer chains are of perfluorocarbon monomers are preferred for use. Illustrative of such monomers are tetrafluoroethylene (TFE), hexafluoropropylene, CTFE, bromotrifluoroethylene and perfluoroalkyl vinyl ethers. Mixtures of monomers can also be used.

Even more preferred as catalysts are copolymers of TFE or CTFE and a perfluoroalkyl vinyl ether containing sulfonic acid group precursors and optionally containing oxygen ether linkages in the perfluoralkyl group. Most preferred in this class are copolymers of TFE or CTFE and a monomer represented by the structure

These polymers are prepared in the sulfonyl fluoride form and are then hydrolyzed to the acid form as described in U.S. Patent 3,692,569.

Most preferred as catalysts are copolymers of TFE and monomers of formula (10) in which the respective monomer weight ratios are 50--75/255-50. Such copolymers, having equivalent weights of 1100, 1150 and 1500, are sold by E. I. du Pont de Nemours and Company as Nafionat perfluorosulfonic acid resin.

The catalyst is ordinarily present in the reaction mass in a catalytically effective amount, which in the usual case means a concentration of about 0.01% to 30%, by weight of the mass, preferably 0.05% to 15%, even more preferably 0.1% to 10%.

The acylium ion precursor used can be any compound capable of generating the acyl oxonium ion of equation (1) under reaction conditions. Thus, the term "acylium ion" as used herein means an ion represented by R'-C+= 0 where R' is hydrogen or a hydrocarbon radical.

Representative of such precursors are acyl halides and carboxylic acid anhydrides. Anhydrides of carboxylic acids whose carboxylic acid moieties contain 1 to 36 carbon atoms are preferred, especially those of 1 to 4 carbon atoms.

Illustrative of such anhydrides are acetic anhydride, propionic anhydride and formic-acetic anhydride. The anhydride preferred for use because of its efficiency is acetic anhydride.

The acylium precursor is ordinarily present in the reaction mass, at least initially, at a concentration of 0.1 to 15 mol percent, preferably 0.7 to 10%.

The molecular weight of the polymer product can be limited by the addition to the reaction mass of an aliphatic carboxylic acid, for example of 1 to 36 carbon atoms, preferably 1 to 5 carbon atoms. Acetic acid is preferred for its low cost and effectiveness.

The acylium ion precursor/acid weight ratio should be within the range of 20/1 to 0.1/1, preferably 10/1 to 0.5/1. Generally speaking, the more carboxylic acid used, the lower the molecular weight of the product.

The aliphatic carboxylic acid is ordinarily added to the reaction mass at a concentration of 0.1 to 10% by weight of the THF, preferably 0.5 to 5%.

Since the preferred acylium ion precursor, acetic anhydride, reacts with THF and the catalyst to give the corresponding acid, separate addition of an acid in that instance is not necessary, although it is generally desirable for improved molecular weight control.

To obtain a product having a commercially desirable number average molecular weight of 650 to 30,000, it is preferred that the acylium ion precursor and carboxylic acid be present in the reaction mass at a combined concentration of 0.5 to 20%, by weight of the reaction mass, preferably 1 to 10%.

The polymerization reaction can be run in a batch mode or continuously.

When run in a batch mode, proper amounts of THF, acylium ion precursor, catalyst and carboxylic acid are placed in a reactor and stirred while reaction conditions are maintained at optimum. When the reactions are finished, the catalyst and the reaction mass are separated, and the product is then separated from the remainder of the mass.

When run continuously, the reaction is preferably and similarly run in a backmixed slurry reactor, with continuous stirring and with continuous addition of reactants and continuous removal of product. Alternatively, the process can be run in a pipeline reactor.

In a pipeline reactor, the reaction is run under plug-flow conditions, whereby premixed reactants move through the reactor, which is packed with catalyst. The movement is continuous, with little or no mixing of the initial feed with partially converted reactants, and with the reactants reacting as they move along.

The pipeline reactor is preferably oriented vertically, with the reactants moving upwardly through the catalyst, which tends to suspend the catalyst and make the flow of reactants freer. The reactants can also move downward through the reactor, but this tends to compact the catalyst and restrict the flow of reactants.

In either the slurry reactor or the pipeline reactor, it is preferable to adjust the temperature in the reaction zone, the concentration of rectants in the reaction zone, and the flowrate of the reactants into and out of the reaction zone so that 5 to 85%, by weight, preferably 15 to 60%, even more preferably 15 to 40% of the THF is converted to ester end-capped PTMEG on each pass through the reactor. The effluent of each pass, after the product has been removed, can be recycled to the reactor.

It is also preferable that at least 40%, by weight, even more preferably 80 to 90%, of the acylium ion precursor be consumed on each pass of reactants through the reactor.

With proper adjustment of concentrations of rectants in the feed stream, of flowrates and of temeprature, all of this can ordinarily be accomplished with a residence time of the reactants in a continuous reactor of 10 minutes to 2 hours, preferably 15 to 60 minutes, even more preferably 20 to 45 minutes.

Residence time (in minutes) is determined by measuring the volume (in milliliters) of the reaction zone and then dividing this figure by the flowrate (in milliliters per minute) of the reactants through the reactor. In a slurry reactor, the reaction zone is the entire volume of the reaction mixture; in a pipeline reactor the reaction zone is the zone containing the catalyst.

In either the batch or continuous mode, the polymerization is ordinarily run at atmospheric pressure, but reduced or elevated pressure may be used to aid in controlling the temeprature of the reaction mass during the reaction.

The temperature of the reaction mass is kept in the range of 0 to 1200C, preferably 220 to 650C.

It is preferable to exclude oxygen from the reaction zone. This can be done by running the process in an inert atmosphere, such as of dry nitrogen or argon.

The time required for the reaction to reach a given conversion of THF to polymer depends upon the conditions under which it is run. Time will therefore vary with temperature, pressure, concentrations of reactants and catalyst, and like factors. Generally, however, in a continuous mode, the reaction is run for 10 minutes to 2 hours, preferably 15 minutes to 60 minutes, even more preferably 20 to 45 minutes. In the batch mode, the reaction is ordinarily run for 1 to 24 hours On completion of the-polymerization reaction, the catalyst can be separated from the reaction mass by filtration, decantation or centrifugation, and reused. If the reaction is run in a continuous fashion, the catalyst can simply be allowed to remain in the reactor while fresh reactant is fed in and product is removed.

In either the batch or continuous mode, after removal of the catalyst, the polymer product is separated from the reaction mass by extracting residual unreacted THF, acylium ion precursor and carboxylic acid by distillation or by stripping with steam or an inert gas such as nitrogen.

The poly(tetramethylene ether) diacetate (PTMEA) thus produced can range in physical properties from a clear viscous liquid to a waxy solid. The number average molecular weight of the product can be as high as 30,000, but will usually range from 650 to 5,000, and more commonly will range from 650 to 2,900.

Number average molecular weight is determined by end group analysis using spectroscopic methods well known in the art.

The molecular weight of the PTMEA can be kept within any range desired by - varying the carboxylic acid-acylium ion precursor ratio in the reactant feed, by varying the total amounts of carboxylic acid and precursor in the reactant feed, by varying the temperature of the reaction mass within certain limits, by controlling the residence time of the reactants in the reaction zone and by varying the catalyst concentration. Generally speaking, use of larger amounts of carboxylic acid and/or acylium ion precursor gives polymers with lower molecular weights; lower reaction temperatures favor production of polymers with higher molecular weights; higher catalyst concentrations favor lower molecular weights.

The PTMEA thus produced is then converted to PTMEG by reacting it with an alkanol in a basic medium, using as a catalyst an oxide, hydroxide or alkoxide of calcium, strontium, barium or magnesium. This conversion is easily accomplished and gives nearly catalyst-free PTMEG.

This alcoholysis proceeds according to the following illustrative equation:

where R is an alkyl radical of 1 to 4 carbon atoms, and is a poly(tetramethylene ether) polymer chain.

In the alcoholysis, a mixture of PTMEA, catalyst and alkanol is first prepared.

This can be done by simply mixing the components together in a reactor, in any order. Preferably, the catalyst is first slurried in the alkanol and this slurry is then mixed with a solution of the PTMEA in alkanol.

The mixture is generally prepared so that it contains 5% to 80%, by weight of PTMEA 0.05% to 20%, by weight of catalyst, and a complementary amount of alkanol. Preferably, the mixture contains 20% to 60% of ester, 0.1% to 5% of catalyst and a complementary amount of alkanol.

The PTMEA can be added to the reactor as it is needed, or it can be fed directly from the apparatus used to prepare it.

The catalyst used in this mixture is an oxide, hydroxide or alkoxide (in which the alkyl group contains I to 4 carbon atoms) of calcium, barium, strontium or magnesium. The preferred catalyst is calcium oxide. The catalyst is rodinarily particulate and is preferably in powder form.

The alkanol in the mixture is one containing 1 to 4 carbon atoms. Methanol is preferred, especially when calcium oxide is used as the catalyst.

It is most important that the mixture be basic, i.e., that it have a pH value of above 7, preferably 10 to 12, for if the pH value is below about 7, the process slows to the point of uselessness or does not proceed at all. In the usual case, the mixture will have the proper pH value inherently if concentrations of components are held within the limits just recommended. If, for some reason, component concentrations must be varied from these recommended figures, or if acid enters the mixture with one of the components, the pH of the mixture may have to be brought to 7 or above by adding more catalyst.

The mixture is then brought to its boiling point and held there, with stirring, while vapors of the alkanol/alkyl ester azeotrope which form are continuously withdrawn from the reaction zone. In the usual case, the boiling point of the mixture will be in the range of about 50 to 1500C. If temperatures higher than this are required, the reaction can be run under a pressure of up to 100 atmospheres.

This boiling and withdrawl of azeotrope is continued until the alcoholysis is substantially complete, i.e., until no more alkyl ester forms.

The alcoholysis can be conducted batchwise or in continuous fashion. The continuous mode is preferred for its efficiency.

Although the alcoholysis can be run in a single stage, it is preferably run in two stages, especially when run continuously, because this gives a higher degree of conversion. The continuous two-stage process is run exactly as the one-stage process except that the contents of the first reactor are transferred to a second reactor when alcoholysis is about 98% complete, which ordinarily requires a residence time of about 90 minutes. Alcoholysis is completed in the second reactor, and this genreally requires a residence time of another 90 minutes.

It may be desirable that alkanol be continuously added to the second reactor in an amount equal to the amount of alkanol in the azeotrope withdrawn.

After the alcoholysis is complete, the catalyst and such other insoluble materials as may be present are removed from the reaction mass by conventional techniques such as filtration, decantation or centrifugation. Ordinarily and preferably, the catalyst is filtered from the reaction mass and recycled to one of the reactors, but the reaction mass can also be withdrawn from the reactor through a filter which holds back the catalyst and other insolubles and keeps them in the reactor.

It may also be desirable, before or after the separation of catalyst, to strip the reaction mass of residual alkanol and alkyl ester byproduct. This can be done by conventional engineering techniques.

The PTMEG product can be put to any conventional use, such as the preparation of polyesters or polyurethanes according to methods well known in the art.

EXAMPLES A NafionB perfluorosulfonic acid resin powder with an equivalent weight of 1,100 and an average particle size of 0.2 to 0.5 mm was used in the following examples and is referred to as the catalyst.

All polymerizations were conducted at 220C and at ambient pressure, except where indicated otherwise.

Screen meshes are expressed in Tyler Series sizes.

Percentages are by weight unless otherwise indicated.

Although molecular weights were not determined for some of the samples, the intrinsic viscosity figures given in their stead are indicative of variations in molecular weight. Intrinsic viscosity is the value obtained by extrapolating to zero concentration the ratio of the specific viscosity of a given solution to the concentration of that solution.

Example 1.

A 1.75 g sample of catalyst was added to a flame dried and tared flask which was then evacuated to 10-5 mm Hg pressure and heated to l200C.for 16 hours. By reweighing the flask it was determined that 1.60g of anhydrous catalyst was present.

Next, 134.8 g of THF, dried over lithium aluminum hydride, and 1.08 g of acetic anhydride were distilled into the flask using standard vacuum line technique, and the mixture was stirred for 24 hours. Then 500 ml (444 g) of THF was added to reduce solution viscosity, and the catalyst was removed by filtration.

Evaporation of unpolymerized THF under reduced pressure, followed by drying at 800C and 120 mm of Hg gave 89.8 g (66 weight percent conversion of the THF) of polymer with an intrinsic viscosity [11], of 1.05 and an absorption peak at 1750cam~' in the infrared spectrum, charactersitic of acetate end groups.

Under similar conditions but in the absence of acetic anhydride and therefore outside of the invention 51.4 g (36% conversion) of polymer was obtained with [#] = 4.04, indicative of a very high molecular weight, and with no acetate end groups.

Example 2.

Wet catalyst (about 1.0 g containing about 0.3 g water) was mixed with 30 ml (26.6 g) of THF, and the THF was decanted. Fresh THF (50 ml, 44.4 g) and 2.16 g (2 ml) of acetic anhydride were added to the catalyst and the mixture was stirred for 4 hours. This was more than enough acetic anhydride to combine with all the water present, forming acetic acid.

After filtering the catalyst from the reaction mass, stripping the solvent under vacuum, and drying the product at 90 C at 50 mm Hg, 12.5 g (30% conversion) of polymer with [#] = 0.30 was obtained (Sample 1).

Under similar conditions but using dry catalyst and in the absence of water, 38% conversion of THF to polymer with [#] = 0.78 was obtained in 2 hours (Sample 2). The results are summarized below.

Acetic Catalyst(1) THF Anhydride Time PTMEA Conversion Sample No. (g) (g) (g) (hr) (g) (%) [#] 1 0.7 44.4 2.16 4 12.5 30 0.30 2 0.84 72 2.1 2 27 38 0.78 (1) Dry weight Example 3.

A series of separated batch runs covering the range of 9:1 to 1:9 weight ratio of acetic anhydride: acetic acid was carried out by adding 3 g of catalyst to a reaction vessel, adding 70 ml (62 g) of a solution in THF of varying amounts of acetic anhydride and acetic acid, and then stirring the reaction mass at 22 C for the indicated time.

Samples were removed at intervals for percent conversion and molecular weight determination. The results are presented below (Samples 3 to 9).

These experiments show that molecular weight can be a function of acetic anhydride:acetic acid ratio and of time.

Acetic Acetic Ratio THF Anhydride Acid Anhydride Time Conversion Sample No. (g) (g) (g) Acid (hr) % Mn 3 55.8 3.1 3.1 1:1 1.5 37 1528 4 55.8 3.1 3.1 1:1 5.5 60 1488 5 55.8 3.1 3.1 1:1 21 61 1397 6 55.8 5.6 0.6 9:1 1.5 47 2808 7 55.8 5.6 0.6 9:1 5.5 74 1270 8 55.8 5.6 0.6 9:1 21 82 1002 9 55.8 0.6 5.6 1:9 21 23 2304 Example 4.

A batch polymerization of THF was carried out as in Example 3, using 1 g of catalyst with 0.36 g of trifluoroacetic acid and 21 ml (18.7 g) of solution of THF containing 10% acetic anhydride. The results are presented below (Samples 10 to 12).

Ratio Sample Anhydride: Time Conversion No. Acid (hr) % 10 5.8:1 3 58 11 5.8:1 8 78 12 5.8:1 24 83 The resulting polymers were viscous oils having both acetate and trifluoroacetate end groups.

Example 5.

A mixture of 75.5 g THF, 3.1 g propionic anhydride and 1.0g catalyst was stirred for 4 hours.

After the catalyst was removed by filtration and the unreacted THF was removed by vacuum distillation, 24.1 g (33.5% conversion) of polymer with propionate end groups was obtained.

Example 6.

A mixture of 75.5 g THF, 4.2 g formic-acetic anhydride and 1.0 g catalyst was stirred for 2.5 hours.

After the catalyst was removed by filtration and the unreacted THF was removed by vacuum distillation, 16.3 g (23% conversion) of polymer with [9] = 0.33 was obtained.

Example 7.

A mixture of 72.0 g THF, 5.0 g propionic anhydride, 3.0 g acetic acid and 1.0 g catalyst was stirred for 6 hours. Analysis of the mixture from which the catalyst had been removed by filtration, by NMR spectroscopy showed that 19% of the THF had been converted to polymer having propionate and acetate end groups in a 3:2 ratio and a Mn of 1500.

Example 8.

A mixture of 2 g catalyst, 100 g THF, 10 g PTMEG having an Mn of 650, and 6 g acetic anhydride was stirred at 250C for 4 hours. The catalyst was then separated from the mixture by filtration and unreacted monomer was removed by vacuum distillation. The polymer yield was 42 g and the molecular weight of the PTMEG diacetate was 2000.

Example 9.

A 1 g sample of catalyst, dried as in Example 1, was added to a monomer mixture consisting of 80 g of THF and 20 g of 3-methyl-tetrahydrofuran (3MeTHF). A mixture of 9 g of acetic anhydride and 1 g of acetic acid was added, and the system was stirred for 4 hours at 220 C. At this point, the polymerization was interrupted by removing the catalyst by filtering it from the colorless, viscous polymer solution. Unreacted monomer was removed from the reaction mass by vacuum distillation, and the polymeric product was extracted with water and dried at 2 mm of pressure and 80"C to constant weight.

Conversion to diacetate copolymer: 56% Yield of pure copolymer (% of total polymer): 94% Mn: 3130 Molar composition of copolymer: 11% 3 MeTHF units 89% THF units Example 10.

A 1 g sample of catalyst, dried as in Example 1, was added to a monomer mixture consisting of 40 g of THF and 10 g of 2-methyl-tetrahydrofuran (2 MeTHF). A mixture of 4.5 g of acetic anhydride and 0.5 g of acetic acid was added, and the system was stirred for 5 hours. At this point, the polymerization was interrupted by removing the catalyst by filtering it from the colorless, viscous polymer solution. Unreacted monomer was removed from the reaction mass by vacuum distillation, and the polymeric product was washed with water and dried as in Example 9.

Conversion to diacetate copolymer: 44% Yield of pure copolymer (% of total polymer): 89% Mn: 1800 Molar composition of copolymer: 6.5% 2 MeTHF units 93.2% THF units Example 11.

A vertical pipeline reactor was used having a volume of 50 ml and an inside diameter of 25 mm, and having stainless steel screen packs (120 mesh) to retain the catalyst at each end of the tube. Valves and tubing were provided to feed the reactants in below the bottom screen pack and to take reactants and products off above the top screen pack. A constant temperature bath surrounded the reactor.

With 5 g of catalyst in the reactor chamber, dried as in Example 1, and a reactant feed composition of 90% THF, 9% acetic anhydride and 1% acetic acid, the reactants were fed in and product was removed at a rate to give a controlled residence time.

With a residence time of 190 minutes, the conversion of THF to PTMEA was 49% with Mfl of 1,500 to 2,000. With a contact time of 425 minutes, the conversion was 74% and the polymer had Mn of 900 to 1,200. Runs made in the same reactor, with the same feed composition and with a 43 minute residence time, gave a THF conversion of 39% and a productivity of 5 g PTMEA/g catalyst/hr.

The same system can be operated in either an upflow or downflow mode.

Example 12.

A back-mixed slurry reactor having a volume of 100 ml was used.

The reactor was operated with a liquid volume of 50 ml. The reaction mixture was stirred magnetically. A constant temperature bath surrounded the reactor.

With an initial charge of 1 g of catalyst, dried as in Example 1, and a reactant feed composition containi

Example 14.

A 25 g sample of PTMEA was dissolved in 100 ml of methanol. After addition of 0.5 g of calcium hydroxide, the mixture was heated to 650C and held there for 3 hours, with stirring, while vapors of the methanol/methyl acetate azeotrope which formed were withdrawn.

The product was then dried for 1 hour at 850C in a vacuum of about 1 mm of mercury. Filter aid, 0.1 g, was added and the product was filtered to remove insoluble material.

The final product contained less than 2 ppm of calcium, as determined by flame photometry. Infrared spectroscopic analysis demonstrated that alcoholysis was complete.

Example 15.

A 25 g sample of PTMEA was dissolved in 100 ml of methanol, as in Example 14. Instead of calcium hydroxide, 0.5 g of calcium oxide was added, and the mixture processed as in Example 14.

Infrared spectroscopic analysis showed that alcoholysis was complete.

Example 16.

A 36 g sample of PTMEA was dissolved in 160 ml of methanol, and 1 g of barium oxide was added to the solution. The resulting slurry was heated to 65"C and held there for 3 hours, while vapors of the methanol/methyl acetate azeotrope which formed were continuously withdrawn.

The resulting product was processed as in Example 14, to give PTMEG free of ester groups.

Claims (41)

WHAT WE CLAIM IS:

1. A process for preparing ester end-capped poly(tetramethylene ether) glycol, or ester end-capped poly(tetramethylene ether) glycol copolymer, the process comprising (A) bringing together, under conditions suitable for reaction: (1) tetrahydrofuran, and optionally, up to 50% by weight of the tetrahydro furan of a copolymerizable alkyl tetrahydrofuran represented by the structure

where any one of R1,R2,R3 or R4 is an alkyl radical of 1 to 4 carbon atoms, the remaining R's being hydrogen; (2) an acylium ion precursor, the acylium ion being as defined herein; (3) as a catalyst, a polymer of ethylenically unsaturated monomers, the polymer (a) containing groups of the formula

where -vvvrepresents the polymer chain or a segment thereof; D is hydrogen, an aliphatic or aromatic hydrocarbon radical of 1 to 10 carbon atoms, a halogen or a segment of the polymer chain; X and Y are hydrogen, halogen, or an aliphatic or aromatic hydrocarbon radical or 1 to 10 carbon atoms, at least one being fluorine; R is a linear or branched linking group having up to 40 carbon atoms in the principal chain; and Z is hydrogen, halogen, or an aliphatic or aromatic hydrocarbon radical of 1 to 10 carbon atoms and (b) being effectively free of functional groups which interfere with the reaction and then (B) separating the resulting ester-end cap poly(tetramethylene ether) glycol product from the reaction mass.

2. A process as claimed in claim 1 in which the acylium ion precursor in (A) (2) is an anhydride or a carboxylic acid.

3. A process as claimed in claim 2 in which the anhydride is an anhydride of a carboxylic acid whose carboxylic acid moiety contains 1 to 36 carbon atoms.

4. A process as claimed in claim 1 in which the acylium ion precursor is acetic anhydride.

5. A process as claimed in any one of claims 1, 2 or 4 in which an aliphatic carboxylic acid is additionally present in step (A).

6. A process as claimed in claim 5 in which the carboxylic acid has 1 to 36 carbon atoms.

7. A process as claimed in claim 5 in which the aliphatic carboxylic acid is one of 1 to 5 carbon atoms.

8. A process as claimed in claim 5 in which the acid is acetic acid.

9. A process as claimed in any one of the preceding claims in which the catalyst has a solubility in the reaction mass of no more than 5% by weight, when run in a batch mode at 220C to 650C.

10. A process as claimed in any one of the preceding claims in which the catalyst in (A) (3) is a polymer of perfluorocarbon monomers.

11. A process as claimed in claim 10 in which the catalyst is a polymer of TFE or CTFE and R is

12. A process as claimed in claim 11 in which the catalyst is a hydrolyzed copolymer of TFE or CTFE and a monomer represented by the structure

the TFE or CTFE and monomer units being present in weight ratios of 50-75/25-50, respectively.

13. A process as claimed in any one of claims 1,2,4 or 5 in which the catalyst is a perfluorocarbon polymer containing groups of the formula

where D is hydrogen, chlorine or fluorine.

14. A process as claimed in any one of claims 1, 2, 4, or 5, in which the catalyst is a hydrolysed copolymer of (a) tetrafluoroethylene and/or chlorotrifluoroethylene and (b) perfluoroalkyl vinyl ether sulfonyl fluoride in which the perfluoroalkyl group may optionally contain oxygen ether linkages.

15. A process as claimed in claim 14 in which the monomer (b) is

16. A process as claimed in any one of the preceding claims conducted in a continuous manner.

17. A process as claimed in any one of claims 13 to 15 conducted in a continuous manner.

18. A process as claimed in claim 16 conducted in a back-mixed slurry reactor.

19. A process as claimed in claim 1 for preparing ester end-capped poly(tetra methylene ether) glycol, the process comprising continuously (A) bring together tetrahydrofuran, acetic anhydride, acetic acid and a catalytically effective amount of a hydrolyzed copolymer as defined in claim .12 and then (B) separating the resulting ester end-capped poly(tetramethylene ether) glycol from the reaction mass.

20. A process as claimed in claim -19 wherein the catalyst is a hydrolysed copolymer of TFE or CTFE and the monomer

21. Ester end-capped poly(tetramethylene ether) glycol or ester end-capped poly(tetramethylene ether) glycol copolymer, when produced by a process as claimed in any one of the preceding claims.

22. Ester end-capped poly(tetramethylene ether) glycol or ester end-capped poly(tetramethylene ether) glycol copolymer, when produced by a process as claimed in any one of claims 13 to 15, 17 and 20.

23. Poly(tetramethylene ether) glycol homopolymer or copolymer when produced from an ester as claimed in claim 21.

24. Poly(tetramethylene ether) glycol homopolymer or copolymer when produced from an ester as claimed in claim 22.

25. A process for preparing poly(tetramethylene ether) glycol homopolymer or copolymer as claimed in claim 23 or claim 24, the process comprising (A) preparing a basic mixture of (1) ester end-capped poly(tetramethylene ether) glycol, (2) a catalyst which is an oxide, hydroxide, or alkoxide of calcium, strontium, barium or magnesium, and (3) an alkanol of 1 to 4 carbon atoms (B) bring the mixture to its boiling point and holding it there while the vapors of the alkanoValkyl ester azeotrope which form are continuously removed from the reaction zone, until conversion is substantially complete; and then (C) removing the catalyst, and optionally the residual alkanol and residual alkyl ester, from the reaction mass.

26. A process as claimed in claim 25 wherein the catalyst in (A) (2) is calcium oxide.

27. A process as claimed in claim 25 or claim 26 wherein the alkanol in (A) (3) is methanol.

28. A process as claimed in any one of claims 25 to 27 wherein the mixture of (A) contains 5 to 80% by weight of ester end-capped poly(tetramethylene ether) glycol, 0.05 to 20% by weight of catalyst and a complementary amount of alkanol.

29. A process as claimed in any one of claims 25 to 28, run in continuous manner.

30. A process as claimed in any one of claims 25 to 29 wherein ester to be converted is an ester of poly(tetramethylene ether) glycol.

31. A process as claimed in any one of claims 25 to 30 wherein step (B) is performed in two stages.

32. A process as claimed in claim 31 wherein the ester to be converted is as defined in claim 30.

33. A process as claimed in claim 25 for converting poly(tetramethylene ether) diacetate to poly(tetramethylene ether) glycol, wherein the mixture prepared in step (A) comprises 5 to 80% by weight of poly(tetramethylene ether) diacetate, 0.05 to 20% by weight of calcium oxide, and a complementary amount of methanol.

34. A process as claimed in claim 33 run in continuous fashion, and wherein step (b) is performed in two stages.

35. A process as claimed in claim 25 wherein the ester to be converted is an ester as claimed in claim 21.

36. A process as claimed in claim 25 wherein the este to be converted is an ester as claimed in claim 22.

37. Poly(tetramethylene ether) glycol homopolymers and copolymers when produced by a process as claimed in any one of claims 25 to 36.

38. Poly(tetramethylene ether) glycol homopolymers and copolymers when produced from an ester as claimed in claim 22 by a process as claimed in any one of claim 25 to 30.

39. A process as claimed in claim 1 substantially as described herein in any one of Examples I to 10.

40. A process as claimed in claim I substantially as described herein in any one of Examples 11 or 12.

41. A process as claimed in claim 25 substantially as described herein in any one of Examples 13 to 16.