GB2217322A - Aryl ketones and polyarylethers made therefrom, and processes for their manufacture - Google Patents

Abstract

Aryl ketones and polyarylethers made therefrom, and processes for their manufacture, are described. The aryl ketones are of the formula <IMAGE> wherein Ph is 1,4-phenylene and X is halogen, preferably F. The polyarylether has repeat units of formula <IMAGE> optionally with repeat units of formula -Phn- wherein n is an integer from 1 to 3 and/or other repeat units, the units being connected by ether linkages. Such polymers are crystalline and have high Tg's relative to Tm's.

Description

Acryl Ketones and Polymers made therefrom This invention relates to aryl ketones, which find particular but not exclusive application in the synthesis of polyetherketones, and to polymers made therefrom.

In the ensuing description the following abbreviations will be used: DSC differential scanning calorimetry; Tm melting point, the temperature at which the main peak of the melting endotherm is observed; Tc temperature at which crystallisation occurs on cooling the melt before or after solidification.

Tg glass transition temperature RV reduced viscosity, as measured at 250C on a solution of l.0g of 3 polymer in 100 cm of solution in sulphuric acid of density 3 1.84glum RV - (TslTo) -1.

The determination of Tg by DSC is carried out by examining a 10 mg sample of polymer in a Perkin Elmer DSC-4 and or DSC-7 instrument, using a heating rate of 200cumin under nitrogen. From the resulting curve the onset of the Tg transition is obtained. This is measured as the intersection of lines drawn along the pretransition baseline and a line drawn along the greatest slope obtained during the transition.

According to a first aspect of the present invention, there is provided an aryl ketone of formula I

wherein Ph is a 1,4-phenylene and X is halogen.

In preferred ketones, which are useful in manufacture of polymers by nucleophilic substitution, X is Cl or especially F.

The difluoro ketone II is especially useful in preparation of commercially attractive polymers

The compounds I and II have the advantage of containing an economically low weight of halogen in relation to commonly used monomers.

These compounds also find applications as intermediate for preparation of bisphenols and diamines.

Accordance with a second aspect of the present invention, the compounds I and II are prepared from meta-terphenyl which may be reacted with halobenzoyl chlorides in the presence of an acid capable of activating the reaction.

The acid may be a Lewis acid which functions as a Friedel-Crafts activator, for example anhydrous aluminium chloride which is preferably used in a molar ratio which exceeds the ketone groups present in intermediates and in acid chlorides; or the acid is a superacid such as a fluoroalkane sulphonic acid, preferably trifluoromethane sulphonic acid, and anhydrous hydrogen fluoride.

When the acid is a Friedel-Crafts activator, a substantially inert solvent has to be provided. Suitable solvents include nitrobenzene and 1,2,4-trichlorobenzene. When the acid is a superacid, the acid itself functions as a solvent.

According to a third aspect of the present invention, an aromatic polyetherketone comprises a repeating unit III

alone or together with other repeating units, said units being connected by ether linkages.

Homopolymers consisting essentially of the units III and copolymers of III with another monomer are crystalline and exhibit high Tg relative to Tm in comparison to previously known polyetherketones, for example polyetheretherketones.

Copolymers preferably include equimolar amounts of repeating units III and repeating units of formula IV Phn IV wherein n is an integer from 1 to 3.

The homopolymer or copolymers may include up to 20X of one or more other units preferably up to 10X for example bis-phenylene units especially of the type not containing electron-withdrawing groups para to ether linkages, for example diphenyl ether, diphenoxybenzene and diphenyl alkane especially diphenylpropane.

The relative proportions are by moles on the total of the three units in combination, ignoring any excess of any of them which may be included for the purpose of controlling molecular weight or providing particular end groups. In addition the polymer may contain up to 20 mole Z of other ether-linkable units.

Polymers of this invention may be characterised by one or more of (i) being 10-60Z crystalline, especially 15-40Z, after annealing; (ii) being tough when formed into an amorphous film by compression moulding and, preferably, being tough when formed into a crystalline film; and (iii) being resistant to a wide range of solvents when crystalline, in particular remaining coherent on immersion of 24 hours of a 0.3 mm film in methylene chloride (CH2Cl2) at 200C, and not dissolving or becoming sticky. Thus these polymers are particularly useful for applications which require resistance to solvents and to high temperatures.

Polymers in accordance with the invention can be melt processed into shaped articles, including films and insulating coatings on electrical conductors or used as matrices in composites. They can be used in applications for which polyaryletherketones have been proposed previously. In particular they may be used for bearings or bearing liners or for those applications which require a combination of one or more of good electrical insulating properties, good resistance to a wide range of chemicals, retention of mechanical properties up to high temperature, good resistance to burning and the emission of low proportions of toxic fumes and with low smoke density on burning. Films whether undrawn, uniaxially-drawn or biaxially-drawn are especially useful when made of these polymers.

Whilst for many applications the polymers of the invention may be used with few if any additives, other than stabilisers, additives may be incorporated for example inorganic and organic fibrous fillers such as of glass, carbon or poly-paraphenylene terephthalamide; organic fillers such as polysulphones, polyketones, polyimides, polyesters and polytetrafluorethylene at various levels of compatibility; and inorganic fillers such as graphite, boron nitride, mica, talc and vermiculite; nucleating agents; and stabilisers such as phosphates and combinations thereof.

Typically the total content of additives if 0.1 to 80Z, especially at most 70Z by weight of the total composition. The composition can contain for example 5 to 30Z by weight of boron nitride; or at least 20Z by weight of short glass or carbon fibre; or 50 to 70t especially about 60X, by volume of continuous glass or carbon fibre; or a mixture of a fluorine-containing polymer, graphite and an organic or inorganic fibrous filler and the total proportion of these additives is preferably 20 to 50X by weight of the total composition.

The composition may be made by mixing the polymer with the additives for example by particle or melt blending. More specifically the polymeric material, in the form of dry powder or granules, can be mixed with the additives using a technique such as tumble blending or high speed mixing. The blend thus obtained may be extruded into a lace which is chopped to give granules. The granules can be subjected to a forming operation, for example injection moulding or extrusion, to give a shaped article.

Alternatively the composition may be film, foil, powder or granules of the polymer with or without particulate additives, laminated with a fibrous filler in the form of mats or cloths.

Alternatively a composition containing fibrous filler may be obtained by passing essentially continuous fibre, for example glass or carbon fibre, through molten polymer or a mixture containing it in a dissolved or finely dispersed state. The product obtained is a fibre coated with polymer and may be used alone, or together with other materials, for example a further quantity of the polymer, to form a shaped article. The production of compositions by this technique is described in more detail in EP-A 56703, 102158 and 102159.

In the production of shaped articles from the polymers of the invention, or from polymer compositions containing them, desirably the crystallising of the polymer is developed as far as possible during the fabrication process, including any annealing stage, because in subsequent use an article which can continue to crystallise can suffer dimensional changes, warping or cracking and general change in physical properties. Furthermore, increased crystallinity results in improved environmental resistance. It also can increase Tg significantly, providing a major advance in heat-resistance.

If desired, for further improved crystallisation behaviour, polymers of the invention may be modified by forming, on the polymeric chains, terminal ionic groups - A - X, where A is an anion and X is a metal cation, as described in more detail in our EP-A 152161. The anion is preferably selected from sulphonate, carboxylate, sulphinate, phosphonate, phosphate, phenate and thiophenate and the metal cation is an alkali metal or alkaline earth metal. By such modification the temperature Tc for the onset of crystallisation, may be raised by at least 20C in comparison with a similar polymer not containing the ionic end-groups. However, useful polymers are obtained even when there is little or no change in Tc if sufficient nucleation results from the presence of end groups to increase the number of spherulites in comparison with a similar composition not containing the ionic end groups.

Such modified polymers are most suitably produced by reaction of a preformed polymer with reactive species containing the ionic group. For example, if the polymer has a terminal group selected from fluoro, chloro and nitro the reactive species contains a nucleophilic group such as a phenate or thiophenate or a group of formula - A - X.

Modified polymers containing terminal ionic groups may be used alone or in a blend with unmodified polymers.

The polymers may in principle be made by an electrophilic process but are most suitably made by a nucleophilic process in which halides and phenols corresponding to the specified repeating units are polycondensed together in presence of one or more bases.

According to a fourth aspect of the present invention a process for preparation of a polyarylether, comprises polycondensing, under substantially anhydrous conditions and in the presence of a base, at least one compound of the formula V

optionally in the presence of at least one compound of formula VI 3 4 Y Ph Y VI n VI wherein Ph and n are as hereinbefore defined.

1 2 3 4 Y and Y and, when present, Y and Y are each independently a halogen atom or a group -OH, the proportions of the compounds V and, 1 2 3 when present, VI and the nature of Y and Y and, when present Y and 4 Y , are such that the halogen atoms and -OH groups are present in substantially equimolar amounts.

Further, any of the repeating units can be introduced in the form of a polymer with any of the others, possibly as a residue left over in the reactor from a previous polycondensation leading to a polymer of the same structure or a structure tolerable as a blend or impurity. In any of these systems involving a haloaromatic reactant a copper catalyst can be used. A copper catalyst must be used if a halide reactant having no activating groups is present. Copper catalyst are of particular value 1 2 where Y and/or Y in formula V is chlorine. The base is preferably at least one alkali metal hydroxide or carbonate, carbonate being suitably introduced as bicarbonate.

The molecular weight of the polymer obtained can be controlled by using an excess quantity of halogen or -OH as above- mentioned, and alternatively or additionally by including in the reaction mixture a small proportion, for example less than 5Z mole, and especially less than 2Z mole relatively to the monomers andlor the polyarylethersulphone, of a monofunctional compound such as a phenol or, preferably an activated arylmonohalide.

The polycondensation reaction may be carried out in the presence or absence of a solvent.

Preferably a solvent is employed and is an aliphatic or aromatic sulpoxide or sulphonate of the formula R -SO R where a is 1 or 2; and R and R', which may be the same or different, are alkyl or aryl groups, and may together form a divalent radical.

Solvents of this type include dimethyl sulphoxide, dimethyl sulphone, and sulpholane (l,l-dioxothiolan) but the preferred solvents are aromatic sulphones of the formula

where T is a direct link, oxygen or two hydrogens (one attached to each benzene ring); and Z and Z1, which may be the same or different, are hydrogen or alkyl, alkaryl, aralkyl or aryl groups.

Examples of such aromatic sulphones include diphenylsulphone, ditolylsulphone, dibenzothiophen dioxide, phenoxathiin dioxide and 4-phenylsulphonyl biphenyl. Diphenylsulphone is preferred. Other solvents that may be used are to be found among that class classified as dipolar and aprotic, for example N-methyl-2-pyrrolidone. In addition co-solvents and diluents may be present. An azeotrope may be used to remove water from the reaction mixture.

The proportion of solvent used is typically such that the content of polymer and polycondensable material present is in the range 15-45Z by weight, it need not all be in solution, and it may be advantageous to operate such that polymer separates as it is formed.

In the polycondensation reaction mixture, if an alkali metal hydroxide is used, this is preferably pre-reacted with the halophenol or bisphenol. The resulting phenate should preferably be in a finely divided form, for example having a particle size of less than 1.0 preferably less than 0.5 mm more preferably less than 0.1 mm. The phenate is conveniently formed in aqueous or methanolic solution and, since the polycondensation should be effected in the essential absence of -OH containing compounds such as water and alcohols, it is necessary to remove such compounds prior to effecting the polycondensation.Thus the halophenol or bisphenol may be stirred in a solution of alkali metal hydroxide in water or a 90:10 by volume mixture of methanol and water, preferably in the ratio of 1 mole of phenol groups to one mole of hydroxide, until it has dissolved; then the solvent may be evaporated off, for example by spray drying. Any hydrated phenate obtained is preferably dehydrated for example by evaporation under reduced pressure, or by heating, preferably in the presence of a diaryl sulphone, at above 1500C, preferably above 2000C and preferably under partial vacuum, eg 25 to 400 torr. Dehydration of the phenate may be advantageous because if the diaryl sulphone does not boil, there is no splashing of the phenate on the walls of the reaction vessel and hence stoichiometry of the polycondensation reaction is maintained.Any dihalo-benzenoid monomers to be used in the polycondensation can be added after evolution of water has ceased, for example as indicated by cessation of foaming. After removal of the water, and addition of any necessary dihalo-benzenoid monomers and/or additional base, the temperature is increased to the polycondensation temperature.

If the base is an alkali metal carbonate added as such or as bicarbonate, whether for the whole base requirement or as an addition to the phenate, it is preferably anhydrous. However, if hydrated it may be dehydrated during heating up to the polycondensation temperature if that temperature is high enough.

The condensation agent may comprise one or more alkali or alkaline earth carbonates. In this specification it is to be understood that bicarbonates may be employed in addition to or in place of carbonates.

Generally a mixture containing an alkali or alkaline earth carbonate and a higher alkali carbonate is preferred. The higher alkali carbonate may be potassium carbonate although the caesium or rubidium salts may be employed. The alkali or alkaline earth carbonate may comprise sodium carbonate, lithium carbonate or other alkaline earth carbonates or mixtures thereof. Mixtures may also include a minor proportion of the higher alkali carbonate, the latter serving to activate the larger proportion of lower alkaline earth carbonates. Use of such mixtures is disclosed in GB 1586972. Use of lithium carbonate in admixture with potassium carbonate is illustrated in US 4636557.

Sole use of a higher alkali carbonate or use of a relatively high proportion of the latter allows use of cheaper but less reactive chloromonomers, particularly chloro-sulphones. Sole use of potassium carbonate or caesium carbonate or mixtures thereof has been found to be particularly efficacious.

The base is desirably used in a finely divided form since we have found that with coarse materials the product obtained may have a lower IV. The base or mixture of bases may also be milled to reduce particle size and increase surface area prior to use.

In order to achieve a satisfactory molecular weight the alkali metal hydroxide, carbonate or bicarbonate should be used preferably in excess over the stoichiometric proportion, the excess being particularly in the range 1 to 15X, for example 2Z, molar.

The polycondensation may also be conducted in the presence of an additional salt or salts especially where the cation comes from Group IA or lIA of the Periodic Table and especially where anion is a halide, an aryl sulphonate a carbonate, a phosphate, a borate, a benzoate, a terephthalate or carboxylate. Such salts may be generated or added, at any stage of the polycondensation.

If a copper containing catalyst is used the copper is preferably not more than 1Z, preferably less than 0.4Z, but desirably at least 0.1Z, molar with respect to the monomers. A wide range of materials may be used, cupric and cuprous compounds and also metallic copper and suitable alloys being usable to introduce the copper containing catalyst. Preferred copper compounds are essentially anhydrous and include cuprous chloride, cupric chloride, cupric acetylacetonate, cuprous acetate, cupric hydroxide, cupric oxide, basic cupric carbonate, basic curpic chloride and particularly cuprous oxide. Catalysis by copper is described in more detail in our EP-A 182648 published 28 May 1986 and British application 8527756 filed 11 November 1985.The stoichiometric excess of the alkali metal hydroxide, carbonate or bicarbonate is calculated after allowing for reaction with the copper compound if it is a salt of a strong acid and disregards any basicity of the copper compound.

If the polycondensation is effected in the presence of a copper containing catalyst, removal of copper residues from the polymer at the completion of the polymerisation is very desirable. The residues may be removed using a complexing agent such as ethylenediamine tetraacetic acid and thereafter washing the polymer with water or admixture of water and methanol.

The polycondensation reaction is carried out at least 1500C preferably in the range 2500C to 4000C, particularly 2800C to 3500C.

An increase in reaction temperatures leads to shorter reaction times but with risk of product decomposition and! our side reactions whereas a decrease in reaction temperature leads to longer reaction times but less product decomposition. However a temperature should be used which maintains the polymer at least partly in solution. In general the solubility of polymer in the polycondensation solvent, for example a diaryl sulphone, increases with temperature. Solubility also increases with increasing proportion of sulphone and ether groups in the polymer chain, hence polymers chain, hence polymers having a higher proportion of sulphone groups can, if desired, be produced at slightly lower polymerisation temperatures.It has been found that better results are obtained if after melting the reactants, the temperature is increased to the polycondensation temperature over several hours.

In order to obtain products of improved properties, it may be advantageous to use a prepolycondensation stage in which the monomers are heated together at a temperature at which some oligocondensation occurs but little, if any, polycondensation occurs. Such prepolycondensation can be effected at 2000C to 2500C, particularly 2200C to 2450C. The prepolycondensation is believed to result in the formation of relatively involatile oligomers and hence to reduce the possibility of volatile monomers being removed from the reaction mixture.

The polycondensation is preferably carried out in an inert atmosphere, for example argon or nitrogen. The reaction vessel can be made from glass but for operation on a large scale is preferably made from stainless steels (other than those which undergo surface crazing at the reaction temperatures in the presence of alkali metal halide), or made of, or lined with, titanium, nickel or an alloy thereof or some similarly inert material.

To neutralise any reactive oxygen-containing anions, a reagent therefor may be introduced into the polycondensation reaction. Reactive monofunctional halides, for example methyl chloride, and reactive aromatic halides such as, for example, 4,4'- dichlorodiphenylsulphone, 4,4 '-dichlorobenzophenone, 4- chlorodiphenylsulphone or 4-chlorobenzophenone are particularly suitable.

At the completion of polycondensation, the reaction mixture may be (i) allowed to cool and, depending on the polycondensation solvent, to solidify, (ii) ground, (iii) treated to remove any polymerisation solvent, for example by extraction with a solvent therefor, conveniently a mixture of acetone or an alcohol for example methanol, then with water to remove the salts, and finally (iv) dried. Additionally, the polymer may be treated to remove copper residues.

The polymers of this invention are very highly crystalline as made. This crystallinity is lost on melting and amorphous products may be made by quenching thin specimens into cold water. Crystallinity may be restored by slowly cooling the melt, at about 200cumin, or by annealing at a temperature between Tg and Tm. The products of this invention are conveniently annealed at 3000C for 90 minutes.

Crystallinity may be assessed by several methods for example by density, by ir spectroscopy, by X ray diffraction or by DSC. The DSC method has been used to evaluate the crystallinity that developed in samples annealed at 3000 for 90 mins in a nitrogen atmosphere. A heating rate of 200cumin was used until a temperature of 4500C was attained. A baseline was then constructed under the melting endotherm and the enclosed area used to calculated the heat of fusion of the samples in jouleslg. Assuming a heat of fusion of 130 joulesig for the crystalline material present, which could be in error by as much as 20Z, the degree of crystallinity was calculated.

We refer to degrees of crystallinity of: 30Z or above as very highly crystalline 20Z as highly crystalline 10Z as crystalline below 10Z as slightly crystalline At least 10Z crystallinity is required for useful products to be made, that is products with enhanced solvent resistance, but values of at least 20Z are preferred.

When the toughness of the polymers is to be determined, the test most frequently used consists in compression - moulding a film about 0.3 mm thick from a sample of the polymer at a temperature at least 40"C above the polymer melting point in a press(4400 MNlm for 5 minutes), then either cooling the film slowly to induce complete crystallisation else quench cooling and annealing it to induce the requisite ; crystallisation. The film is flexed at room temperature, eg 20-250C, through 1800 to form a crease, whereby the two faces of the film formed about the crease touch. The film is compressed manually to form the crease line.If the film survives this treatment without breaking (eg snapping or tearing) it is deemed to be tough; if it fails on the formation of the crease, it is deemed to be brittle and if it fails after folding but during creasing it is regarded as moderately tough.

The invention is illustrated by the following Examples ExamPle 1 23g (0.1 mol) of m-terphenyl, 40 ml of 1,2,4-trichlorobenzene, 39.7g (0.25 mol) of 4-fluorobenzoyl chloride and 37.4g (0.28 mol) of crushed anhydrous aluminium chloride were stirred together under nitrogen. The system was then slowly heated to 1000C over eighty minutes, cooled and poured into water. The organic material was separated and washed several times with water followed by methanol.

13 After drying the product was examined by C nmr and ir and found to be essentially consistent with the structure:

This melted at 2390C - 2420C and was obtained in 54Z yield.

Recrystallisation from 1,2-dichlorobenzene raised the melting point to 242.5-243.50C and analysis by high pressure liquid chromatography showed the purity had increased from 90 to 96Z.

Example 2 Example 1 was repeated except that 1,2-dichloroethane was used in place of 1,2,4-trichlorobenzene and the temperature was raised to 710C over eighty minutes. A 55Z yield of crude product mp 230-2370C was obtained which was raised to 242.6 - 243.50C by recrystallisation from 1,2-dichlorobenzene. Analysis by high pressure liquid chromatography showed the purity had increased from 78X to 97X by this recrystallisation.

Example 3 - Polymer with Hydroquinone 4.84g (102 mmol) of the product of Example 2, 30g of diphenylsulphone, 1.10g (100 mmol) of 1,4-dihydroxybenzene and 1.42g of anhydrous potassium carbonate (sieved to pass 300 microns) was charged to a 250 mml flask and purged with nitrogen. The flask was lowered into an oil bath at 1700C and stirring started under a slow stream of nitrogen. The temperature was then raised to 3050C over five hours. The reaction product was cooled and milled to give a granular product which was extracted with acetone and then with hot water.

The polymer was found to have an RV of 1.08, which indicates a high molecular weight, and this was confirmed by gel-permeation chromatography. Examination by DSC indicated a 'Tg of 1830C and a Tm of 3340C. Amorphous film was prepared by quenching a compression moulding from 4100C. Annealing the amorphous film at 2800C for forty-five minutes caused the sample to become highly crystalline.

ExamPle 4 - Polymer with BiPhenol The polycondensation was conducted in the same manner as for Example 3 except that 1.86g (100 mmol) of 4,4'-dihydroxybiphenyl was used instead of 1,4-dihydroxybenzene and the final temperature of the oil bath was 3300C.

This polymer was shown to have a similar gel-permeation chromatography trace to the polymer of Example 3. Examination by DSC showed the Tg to be 1850C and the Tm to be 3960C. An amorphous sample recrystallised by annealing at 3059C for ninety minutes and shown to be highly crystalline.

Claims (14)

Claims

1. An aryl ketone of formula I

wherein Ph is 1,4-phenylene and X is halogen.

2. An aryl ketone according to claim 1, in which, in formula I, X is CI or F.

3. A process for making an aryl ketone as claimed in claim 1 or claim 2 comprising reacting meta-terphenyl with the respective halobenzoyl chloride in the presence of an acid capable of activating the reaction.

4. A process according to claim 3, in which the acid is a Friedel-Crafts activator, preferably aluminium chloride.

5. A process according to claim 4, in which the Friedel-Crafts activator is aluminium chloride and is present in a molar amount which exceeds the ketone groups present in the reaction.

6. An aromatic polyetherketone comprising a repeating unit III

wherein Ph is 1,4-phenylene, alone or together with other repeating units, said units being connected by ether linkages.

7. An aromatic polymer according to claim 6, in which said other units comprise repeating units IV.

-Phn- IV wherein n is an integer from 1 to 3.

8. An aromatic polymer according to claim 7, which comprises equimolar amounts of units III and IV.

9. An aromatic polymer according to any one of claims 6 to 8, in which said other units are comprised by up to 20Z, preferably up to 10%, of other ether-linkable units.

10. An aromatic polymer according to claim 9, in which said other units are bis-phenylene units, especially bis-phenylene units not containing electron-withdrawing groups para to ether linkages.

11. An aromatic polymer according to any one of claims 6 to 10, characterised by one or more of: i) being 10-60Z crystalline, especially 15-40Z, after annealing; ii) being tough when formed into an amorphous film by compression moulding and, preferably, being tough when formed into a crystalline film; and iii) being resistant to a wide range of solvents when crystalline, in particular remaining coherent on immersion for 24 hours in methylene chloride (CH2Cl2) at 200C and not dissolving or becoming sticky.

12. A process for making a polyarylether comprising polycondensing, under substantially anhydrous conditions and in the presence of a base, at least one compound of formula V

optionally in the presence of at least one compound of formula VI Y3 Ph Y3 VI n wherein Ph is 1,4-phenylene, n is an integer from 1 to 3 and yl and y2 and Y4 are each independently a halogen or a group -OH, the proportions of the compounds V and, when present, VI and the nature of yl and y2 and when present Y3 and Y4, are such that the halogen atoms and -OH groups are present in substantially equimolar amounts.

13. An aryl ketone according to claim 1 or a process according to claim 3 substantially as hereinbefore described with reference to Examples 1 and 2.

14. A polyarylether according to claim 6 or a process according to claim 12 substantially as hereinbefore described with reference to Examples 3 and 4.