GB1558671A

GB1558671A - Aromatic polyethers

Info

Publication number: GB1558671A
Application number: GB517176A
Authority: GB
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1977-02-10
Filing date: 1977-02-10
Publication date: 1980-01-09

Description

(54) AROMATIC POLYETHERS (71) We, IMPERIAL CHEMICAL IN DUSTRIES LIMITED, Imperial Chemical House, Millbank, London, SW1P 3JF, a British Company, 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: This invention relates to aromatic polyethers and in particular to aromatic polyethersulphones and etherketone/sulphone copolymers.

Such aromatic polymers are useful plastic materials generally having high softening temperatures which enable the polymers to be used for applications wherein the polymer may be subject to a high service temperature.

It has been proposed in United Kingdom patent specification 1,078,234 to make such polymers by polymerisation of certain dihalo compounds and certain alkali metal bisphenates in a sulphoxide or sulphone solvent of formula R--SOO-R or R-SO,-R Although it is indicated in specification 1,078,234 that the alkali metal bisphenate may only have a limited solubility in the solvent and that this could provide for easy control of the reaction and, if desired, the slow addition of one reactant to the other to provide satisfactory high molecular weight polymers, a paper by the inventors of specification 1,078,234, Johnson and Farnham, together with some co-workers, in Journal of Polymer Science 1967 Vol 5 Part A-l pages 2375 et seq indicates, at pages 2378 to 2380, that the use of a solvent in which both the polymer and the bisphenate have the highest solubility leads to polymers having the highest molecular weight. The authors of this paper therefore preferred dimethyl sulphoxide, dimethyl sulphone, and 1,1 dioxothiolan (sulpholane) as the solvents and showed that the polysulphones prepared therein from alkali metal salts of bisphenol A (2,2 - bis (4 - hydroxyphenyl)propane) and 4,4' - dichlorodiphenyl sulphone have higher molecular weight than those prepared in diphenyl suiphone.

For more acidic bisphenols, for example, 4,4' - dihydroxydiphenyl sulphone, sulpholane was preferred to dimethyl sulphoxide so that higher polymerisation temperatures could be employed.

It has been proposed in United States patent 3,886,120 to polycondense an alkali metal salt of a bisphenol, for example 4,4' - dihydroxydiphenylsulphone, with certain dihalo compounds for example 4,4' - dichlorodiphenylsulphone, in the absence of a solvent.

This process is said to give polymers of im proved colour compared to the process of Japanese Patent Publication 7799/1967 (which is believed to be equivalent to aforesaid United Kingdom patent 1,078,234.

A comparative example in U.S.P. 3,886,120 shows that the polycondensation of the dipotassium salt of 4,4' - dihydroxydiphenylsulphone with 4,4' - dichlorodiphenyl sulphone in sulpholane (the solvent preferred by Johnson et al for bisphenols for example 4,4' - dihydroxydiphenylsulphone) gave a brown polymer.

Polymerisation in the absence of a solvent presents various practical difficulties; in particular, when operating on a large, commercial, scale, difficulty in stirring the molten reaction mix because of the high melt viscosity of the polymer, and difficulty of removal of the alkali metal halide byproduct of the polymerisation process.

It has also been proposed in United Kingdom patent specification 1,366,114 to commence polymerisation reactions in one solvent for example dimethyl sulphoxide and then to add a higher melting solvent, for example diphenyl sulphone, and then remove the original solvent by distillation.

It has been proposed in United Kingdom patent specification 1,414,421 to make polyetherketones and etherketone/ sulphone copolymers in which up to 25% of the ketone links were replaced by sulphone linkages from certain aromatic dihalides and alkali metal bisphenates under certain conditions using certain aromatic sulphones, for example diphenyl sulphone, as the polymerisation solvent. We have now found that that process is also of particular utility in the production of polyethersulphones and etherketone/sulphone co polymers containing more than 25 T, of sulphone linkages.

Accordingly we provide a process for the production of aromatic polyethers comprising heating, at. temperatures between 200C and 4000C, at least one dihalo compound of formula

where X is halogen, Q is -CO-- or -802-, n is 1, 2 or 3 and m is 0, 1, 2 or 3, with a substantially equimolar amount of at least one alkali metal bisphenate of formula

(at least 95-/ of the -GM groups being in the para position) where M=alkali metal, Q' is O- or -SO,-, n' is 1, 2 or 3 and m'is 0,1,2 or 3, said at least one bisphenate being in the form of a suspension in an aromatic sulphone of formula

in which Y is a direct link, an oxygen atom, or two hydrogen atoms (one attached to each benzene ring) and Z and Z' are hydrogen atoms or phenyl groups and may be the same or different, more than 25% of the total of groups Q+Q' being -SO,-.

The reaction between the dihalo compound and the bisphenate proceeds on an equimolar basis. This can be varied slightly but variation of more than 5% away from equimolar amounts, i.e. outside the molar ratio range of 100:95 to 100:105, seriously reduces the molecular weight of the polymers. However lower molecular weight products are useful for some applications, e.g. adhesives.

The proportions of the reactants determines also the nature of the polymer end groups.

Thus an excess (over equimolar) of the dihalo compound will tend to give halo end groups and this is generally to be preferred for reasons of thermal stability. An excess of bisphenate gives rise to phenate end groups, which may be converted, by means of alkyl halide end stopping agents to hydroxy or alkoxy end groups. [As described in our Belgian patent 819,303 hydroxy end groups may be given by end stopping with an alkyl halide, for example t - butyl chloride that favours the elimination of hydrogen halide rather than displacement of the halide.] Polymers with hydroxy end groups are particularly useful as adhesives.

For these reasons the dihalo compound and bisphenate are preferably employed in the molar ratios between 47:53 and 53:47, particularly 49:51 to 51:49. Where a hydroxy or alkoxy ended polymer is not desired, the dihalo compound preferably comprises 50 to 51 mole of the total reactants.

Examples of suitable dihalo compounds are the following: 4,4' - dichlorobenzophenone (X=CI, Q= CO, m=0) 4,4' - difluorobenzophenone (X=F, Q= CO, m=0) 4,4' - dichlorodiphenyl sulphone (X = Cl Q=SO, m=0) 1,4 (and 1,3) bis - (4 - shlorobenzoyl) benzene (X=CI, Q=CO, m=l, n=l) 4,4' - bis - (4 - chlorobenzoyl) diphenyl (X=CI, Q=CO, m=l, n=2) 4,4' - bis - (4 - chlorophenylsulphonyl) bi phenyl (X=CI, Q=SO,, m=1, n=2) bis - [4' - (4 - chlorophenylsulphonyl) bi phenylyl] sulphone (X=CI, Q=SO2, m=n=2) 4 - [4' - (4 - chlorophenylsulphonyl) bi phenylyl] sulphonyl - 4' - (4 - fluoro phenylsulphonyl) biphenyl (one X=CI, the other X=F, Q=SO2, m=n=2) 4,4' - bis - [4' - (4 - chlorophenylsul- phonyl) bipenylylsulphonyl] biphenyl (X=Cl, Q=SO,, m=3, n=2) 4,4" - bis - (4 - chlorophenylsulphonyl) p- terphenyl (X=Cl, Q=SO,, m= 1, n=3).

The production of the halides where m=2 or 3 and n=2 or 3 is described in United Kingdom patent specifications 1,308,139 and 1,352,137. The latter specification also describes the conversion of such halides into the corresponding bisphenols.

Examples of suitable bisphenates are the dialkali metal salts of the bisphenols corresponding to the above dihalo compounds in which the halogen atoms are replaced by hydroxy groups.

The preferred dihalo compounds are selected from 4,4'-dihalodiphenylsulphones, 4,4' - dihalobenzophenones and 1,4 (and 1,3) bis (4 - halobenzoyl) benzenes, and 4,4' - bis (4 halophenyl sulphonyl) biphenyls.

The preferred bisphenates are the dialkali metal salts of 4,4' - dihydroxybenzophenone, 4,4' - dihydroxydiphenylsulphone and 4,4' bis - (4 - hydroxyphenylsulphonyl) biphenyl.

We prefer to use the monomers where m or m' =0; n or n'=2 or 3; or, when n or n'= 1, Q=CO.

For cost reasons the dihalo compound is preferably 4,4' - dichlorodiphenylsulphone alone, or in conjunction with 4,4' - bis - (4 chlorophenylsulphonyl) biphenyl, 4,4' - dichlorobenzophenone and/or 1,4 - bis - (4 chlorobenzoyl) benzene, while the bisphenate is preferably a dialkali metal salt of 4,4' dihydroxydiphenylsulphone.

A particularly preferred combination is i) 4,4' - dichlorodiphenylsulphone alone or in conjunction with a minor proportion of 4,4' bis - '4 - chiorophenylsuiphonyl) biphenyl, and ii) a dialkali metal salt of 4,4' - di hydroxydiplienylsulphone.

The halogen atoms X in the dihalo compounds are preferably chlorine or fluorine.

The fluorine derivatives are generally more reactive and enable the displacement of alkali metal halide to be carried out more quickly, but are more expensive. Bromine derivatives are also relatively expensive and, although they resemble the chlorine derivatives in performance they usually offer no advantages. Iodine derivatives are generally less satisfactcry.

The alkali metal in the bisphenate is conveniently potassium or sodium.

The polymerisation procedure is as described in United Kingdom patent specification 1,414,421.

Examples of solvents that may be employed include diphenyl sulphone, 4 - phenylsulphonylbiphenyl, phenoxathiin dioxide and dibenzothiophen dioxide. The preferred solvent is diphenyl suiphone. One important feature of the process is that the bisphenate is only very slightly soluble in the solvent at the polymerisation temperature. The bisphenate is mostly present in the reaction mixture in the form of a suspension and for this reason should be added in finely divided form.

The particle size of the bisphenate should be below 1 mm, preferably less than 500 corm.

The bisphenate is conveniently obtained in the finely divided form by spray drying an aqueous solution of the bisphenate. The re sultant powder is then added to the aromatic sulphone solvent and heated, preferably under reduced pressure, to remove any residual water and then the dihalo compound or compounds added and the mixture heated to the poly merisation temperature.

The polymerisation temperature is prefer ably between 250 and 3000C for the poly merisation of 4,4' - dichlorodiphenylsulphone with a alkali metal salt of 4,4' - dihydroxy diphenylsulphone but higher temperatures may be required when utilising reactants contain ing ketone linkages and/or biphenylylene or terphenylylene groups, i.e. when n or n'=2 or 3.

Polymerisataion is conveniently terminated by addition of a reagent reactive with phenate end groups. Suitable reagents include alkyl halides for example methyl chloride, 4,4' dichlorodiphenylsulphone or 4 - chlorophenyl sulphone.

The polymers are generally amorphous thermoplastics of high softening point. Inclu sion of biphenylylene or terphenylylene groups containing reactants tends to increase the softening point while inclusion of a substantial proportion of ketone linkage containing reactant renders the polymer more readily crystallised.

The polymers are of particular utility in applications requiring a high service tempera- ture. Examples of such applications are listed in United Kingdom patent specification 1.016,245 and are particularly suited to the production of mouldings, by for example injection moulding, films and extrusions, e.g.

wire coatings.

The invention is illustrated by the following examples.

EXAMPLE 1 Hydrated dipotassium salt of 4,4' - dihydroxydiphenyl phone was finely ground co pass through a sieve having a mesh opening of 509 ,am. A sample of the ground salt was estimated by titration against a standard solution of sulphuric acid.

Accordingly a sample (37.03 g, corresponding to 0.100 mol) of the hydrated salt was weighed into a glass flask of capacity 250 ml fitted with a stirrer, nitrogen purge, and an air condenser. Diphenylsulphone (50 g) was added and powder blended with the hydrated salt. The flask was flushed with nitrogen and heated on a solder bath at 2300C. As the diphenyl sulphone melted, the stirrer was started, nitrogen purge commenced and the pressure in the flask reduced to 50 torr. Water distilled from the mixture and a slurry of the dipotassium salt in diphenyl sulphone remained in the flask. Care was taken to ensure that the diphenyl sulphone did not boil and hence did not splash the dipotassium salt on to the upper walls of the flask.

The pressure in the apparatus was increased to atmospheric by addition of nitrogen via the nitrogen inlet 4,4' - dichlorodiphenylsulphone (28.64 g; 0.0997 mol) and diphenyl sulphone (19.6 g) were added to the flask and the temperature increased with stirring to 2850C. After 16 hours polymerisation at 2850C, the polymerisation was terminated by bubbling methyl chloride gas through the reaction mixture via a syringe needle for 30 minutes while the mixture was maintained at 2850C.

The resultant reaction mixture was cooled and milled with dry-ice to a powder of particle size less than 1 mm.

The solvent (diphenyl sulphone) and reaction byproduct (potassium chloride) were extracted by means of a Soxhlet type extractor, first with a mixture of water (200 ml) and methanol (700 ml) for six hours; then with water (700 ml) for four hours; and finally with a mixture of acetone (300 ml) and methanol (600 ml) for two hours.

The resultant polymer powder was then dried at 1405C in an air oven for 24 hours at 100 torr.

The resultant off-white coloured powder had a reduced viscosity of 0.48 (measured at 250C on a solution in dimethyl formamide containing 1 g of polymer in 100 ml of solution). A sample (3.5 g) of the polymer was moulded into film about 0.25 mm thick by pressing at 320or for five minutes in an electrically heated press using a force of 20 tonnes on a 10 cm diameter ram.

The film was tough, transparent and pale amber in colour.

EXAMPLE 2 Example 1 was repeated but using a slight excess (28.86 g; 0.1005 mol) of 4,4' - dichlorodiphenylsulphone instead of the slight deficiency.

The polymer powder was off-white and had a reduced viscosity of 0.83.

Film made as in Example 1 was slightly paler than that of Example 1.

EXAMPLE 3 Example 2 was repeated but using a greater excess (29.08 g; 0.1013 mol) of 4,4' - dichlorodiphenylsulphone.

The polymerisation was conducted for 17 hours atter which the reaction mixture was so viscous that it was virtually unstirrable. For this reason end stopping was performed for one hour, changing the position of the methyl chloride injection syringe needle every few minutes.

The resultant polymer powder was off-white in colour and had a reduced viscosity of 1.46.

The presssed film was slightly paler than that of Example 2.

EXAMPLE 4 Example 1 was repeated but using 49.22 g (corresponding to 0.1329 mol) of the hydrated dipotassium salt of 4,4' - dihydroxybenzo- phenone and 75 g of diphenyl sulphone in the dehydration step. 38.94 g (0.1356 mol) of 4,4' dichlorodiphenylsulphone were employed and added together with 17.5 g of diphenyl sulphone after dehydration.

The polymerisation was conducted for 20 hours. The slightly off-white polymer powder had a reduced viscosiy of 0.49, and gave a very pale amber, almost colourless, tough film that was paler than that of Example 3.

WHAT WE CLAIM IS:- 1. A process for the production of aromatic polyethers comprising heating, at temperatures between 2000C and 4000C, at least one dihalo compound of formula

where X is halogen, Q is --COO- or n is 1, 2 or 3 and m is 0, 1, 2 or 3, with a substantially equimolar amount of at least one alkali metal bisphenate of formula

at least 95% of the -GM groups being in the para position) where M=alkali metal, Q' is O- or -SO2-, n' is 1, 2 or 3 and m' is 0, 1, 2 or 3, said at least one bisphenate being in the form of a suspension in an aromatic sulphone of formula

in which Y is a direct link, an oxygen atom, or two hydrogen atoms (one attached to each benzene ring) and Z and Z' are hydrogen atoms or phenyl groups and may be the same or different, more than 25% of the total of groups Q+Q' being -SO2-.

2. A process according to claim 1 in which the molar ratio of the dihalo compound to the bisphenate is in the range 47:53 to 53:47.

3. A process according to claim 2 in which the molar ratio of the dihalo compound to the bisphenate is in the range 49:51 to 51:49.

4. A process according to claim 3 wherein the dihalo compound comprises 50 to 51 mole % of the total reactants.

5. A process according to any one of claims 1 to 4 wherein the reactants are selected from those where m or m'=O; or, where m or are not 0, nor n' =2 or 3, or where nor n'=1, Q=CO.

6. A process according to claim 5 wherein the dihalo compound is selected from 4,4' dihalodiphenylsulphones, 4,4' - dihalobenzophenones and 1,4 - (and 1,4) bis - (4 - halobenzoyl) benzenes, and 4,4' - bis - (4 -halophenylsulphonyl) biphenyls.

7. A process according to claim 5 wherein the bisphenate is selected from the dialkali metal salts of 4,4' - dihydroxybenzophenone, 4,4' dihydroxydiphenylsulphone and 4,4' - bis (4 - hydroxyphenylsulphonyl) hiphenyl.

8. A process according to any one of claims 1 to 7 wherein the halogen atoms X are chlorine or fluorine.

9. A process according to claims 6, 7 and 8 wherein the dihalo compound is 4,4' - di chlorodiphenylsulphone alone, or in conjunc tion with 4,4' - bis - (4 - chlorophenylsul phonyl) biphenyl, 4,4' - dichlorobenzophenone and/or 1,4 - bis (4 - chlorobenzoyl) benzene, and the bisphenate is a dialkli metal salt of 4,4' - dihydroxydiphenyl sulphone.

10. A process according to any one of claims 1 to 9 wherein the alkali metal of the bisphenate is sodium or potassium.

11. A process according to any one of claims 1 to 10 wherein the solvent is diphenyl sulphone.

12. A process according to any one of claims 1 to 11 wherein the particle size of the bis phenate is below 1 mm.

13. A process according to any one of claims 1 to 12 wherein the polymerisation temperature is between 250 and 3000C.

14. A process according to claim 1 substan

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. heated press using a force of 20 tonnes on a 10 cm diameter ram. The film was tough, transparent and pale amber in colour. EXAMPLE 2 Example 1 was repeated but using a slight excess (28.86 g; 0.1005 mol) of 4,4' - dichlorodiphenylsulphone instead of the slight deficiency. The polymer powder was off-white and had a reduced viscosity of 0.83. Film made as in Example 1 was slightly paler than that of Example 1. EXAMPLE 3 Example 2 was repeated but using a greater excess (29.08 g; 0.1013 mol) of 4,4' - dichlorodiphenylsulphone. The polymerisation was conducted for 17 hours atter which the reaction mixture was so viscous that it was virtually unstirrable. For this reason end stopping was performed for one hour, changing the position of the methyl chloride injection syringe needle every few minutes. The resultant polymer powder was off-white in colour and had a reduced viscosity of 1.46. The presssed film was slightly paler than that of Example 2. EXAMPLE 4 Example 1 was repeated but using 49.22 g (corresponding to 0.1329 mol) of the hydrated dipotassium salt of 4,4' - dihydroxybenzo- phenone and 75 g of diphenyl sulphone in the dehydration step. 38.94 g (0.1356 mol) of 4,4' dichlorodiphenylsulphone were employed and added together with 17.5 g of diphenyl sulphone after dehydration. The polymerisation was conducted for 20 hours. The slightly off-white polymer powder had a reduced viscosiy of 0.49, and gave a very pale amber, almost colourless, tough film that was paler than that of Example 3. WHAT WE CLAIM IS:-

1. A process for the production of aromatic polyethers comprising heating, at temperatures between 2000C and 4000C, at least one dihalo compound of formula

14. A process according to claim 1 substan

tially as hereinbefore described and with particular reference to any one of the Examples.

15. Polymers whenever prepared by a process according to any one of claims 1 to 14.