CA1045473A

CA1045473A - Production of aromatic polymers

Info

Publication number: CA1045473A
Application number: CA208,249A
Authority: CA
Inventors: John H. Ridd
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1973-08-31
Filing date: 1974-08-30
Publication date: 1979-01-02
Also published as: JPS5058195A; NL7411197A; FR2242421B1; GB1465686A; DE2441105A1; FR2242421A1; BE819303A

Abstract

ABSTRACT OF THE DISCLOSURE
A process is provided for the production of thermo-plastic aromatic polymers containing hydroxyl or thiol end-groups which comprises reacting a thermoplastic aromatic polymer containing alkali metal phenate, or thiophenate groups with at least one organic halide which undergoes elimination of both hydrogen and halogen atoms e.g. as hydrogen halide, rather tan substitution of the halide, under the reaction conditions employed.

Description

p 26417 ~045473 The present invention relates to aromatic polymers and in particular to thermoplastic aromatic polymers having hydroxyl or thiol end groups, British patent specifications 1 078 234, 1 124 200, 1 133 561, 1 153 035, 1 153 527, 1 153 528, 1 177 183, 1 234 301, 1 246 035, 1 255 588, 1 295 584, 1 296 383, 1 298 821, 1 303 252, 1 352 137 and 1 355 059 and U.S. patent specification 3 819 582 describe methods of making thermoplastic aromatic polymers by nucleophilic polycondensation of alkali metal salts of halophenols (or halothiophenols) i.e, halophenates (or halothiophenates), or of substantially equimolar proportions - of dialkali metal salt of a dihydric phenol (or thiophenol) i,e, a bisphenate (or bisthiophenate), and dihalobenzenoid compound, the halogen atoms of the halophenate (or halothiophenate) and dihalobenzenoid compounds being activated by inert electron withdrawing groups.
The end groups of these polymers as made will generally comprise halogen atoms and/or phenate (or thiophenate) groups, As described in British patent specification 1 342 589, it is possible to vary the relative proportion of halogen end groups to phenate (or thiophenate) end groups by varying the proportions of the reactants from equimolar when using a bisphenate (or bisthiophenate) and dihalobenzenoid compound, or by

-2-~045473 incorporating a small amount of, for example, a bisphenate when using a halophenate.
In order to stabilise the molecular weight and to reduce the reactivity of the polymer, it has been suggested that the reactive end groups should be removed by reaction with an alkyl halide such a~ methyl chloride.
~hus, when the desired molecular weight has been achieved, the polymerisation reaction is terminated by introducing methyl chloride. ~he latter compound reacts with the phenate (or thiophenate) end groups to ~orm methoxy (or methylthio) e~d`groups and hence prevents further polymerisation occurring during the subsequent extraction of the polymer from the polymerisation reaction mixture.
An example of such a polgmerisation termination is described in Canadian patent 847 96~. However,-for some uses of the polymers, particularly for uses as adhesives, it is desirable that the polymers have hydroxyl (or thiol) end groups e.g. as described in aforesaid British patent specification 1 342 589.
Such end groups can be made by hydrolysing phenate, or thiophenate end groups, for example with carbon dioxide and water or by treatment with an aqueous acid such as acetic or hydrochloric acid.
- Howe~er the requirement of having phenate (or thiophenate) end group~ present in the polymer so that they cPn be P 2~417 lU45473 hydrolysed to hydroxyl or thiol end groups necessitates that the polymerisation reaction cannot be stopped by incorporating methyl chloride, which, as explained above gives methoxy or methylthio end groups. However, as explained above it is difficult to control the polymer molecular weight unless the reactive end groups are modified when the desired degree of polymerisation has been achieved, i.e. by incorporating a polymerisation terminator such as methyl chloride.
In theory molecular weight could be controlled by the use of a known excess of bisphenate (or bisthiophenate) over dihalobenzenoid com~,ound, or by the addition of a known small amount of bisphenate (or bisthiophenate) to the polymerisation of the halophenate (or halothiophenate), so that polymerisation is terminated when all the activated halogen atoms of the dihalobenzenoid compound or halophenate (or halothiophenate) have reacted. However, this is not a practical technique because of the presence of ~mall amounts of impurities and the occurrence of side reactions. For example halophenates are liable to contain a small, generally u~measured, amount of bisphenate as impurity.
We have found, however, that certain other organic halides react with phenate (or thiophenate) end groups to give hydroxyl (or thiol) end groups rather than substituted derivatives thereof.

1~45473 ~he organic halides that :may be used are organic compounds which contain a halogen atomland at least one hydrogen atom and which will eliminate both the halogen atom and a hydrogen atom when in the presence of a nucleophile under the conditions prevailing in the reaction with thé phenate (or thiophenate) end-grouped polymer.
Accordingly we provide,a process for the production of thermoplastic aromatic polymers containing hydroxyl or thiol end groups which comprises reacting a thermoplastic aromatic polgmer containing alkali metal phenate or thiophenate end groups with at least one organic halide containing a halogen atom and at least one hydrogen atom that eliminates both the halogen atom and a hydrogen atom when in the presence of a : nucleophile, rather than displacement of just the halogen atom, under the reaction conditions employed.
The thermoplastic aromatic polymer preferably comprises repeating units of the formula .Ar-X-in which Ar is a bivalent aromatic radical and X is -C0-or -S02- and each may vary from unit to unit in the polymer chain (so as to form copolymers of various kinds). ~hermoplastic aromatic polymers generally ', . .

, .

have at leas~ some units of the structure ~Y~X_ in which Y i~ oxygen or sulphur or the residue of an aromatic diol such as 4,4'-bisphenol. One commercially available example of such a pol~mer ha~ repeating units of the formula ~O~S02-another i8 said to have repeating units of the formula ~so2~o~ f~o-andother similar polymers have repeating units of the formula ~3S~So2-The polymer~ may also contain a proportion of a unit having the formula ~ S02-~other group of thermoplastic aromatic polymers that . . . , . . ~ , , .
.. , . . ~ .
. -~ ,~ . ' 1~)454~3 may be used has repeating units of the formula -e3 Y~3~X-(where Y is oxygen or sulphur) which may be copolymerisea with units of other formulae given above.
In the presence of a nucleophile, organic halides are susceptible to two competitive reactions, i.e.
displacement of the halogen atom or elimination of both a hydrogen and the halogen atom. These two reactions may be unimolecular in which a carbonium ion is believed to be formed or bimolecular in which a transition state involving the organic halide and the nucleophile is considered important. In both the unimolecular and bimolecular reaction mechanisms, substitutions at the carbon atom linked to the halogen atom are important in deciding which of the two reactions is favoured. In general the greater the alkyl or aryl substitutions at the a and ~ carbon atom, the more favoured is elimination of both a hydrogen atom and the halogen atom at the expense of displacement of the halogen atom.
Where the organic halide has the hydrogen and chlorine atoms that are eliminated on adjacent carbon atoms, hydrogen halide is eliminated and the corresponding alkene is formed.

- . ~
.
.

, . ' '' ' 1~45473 For the elimination reaction to be favoured the organic halide should preferably have the formula A - C - C-Z or R4- C - I-Z
H R B
where Z is a halogen atom selected from chlorine, bromine and iodine;
R1, R2, R3, R4, R5 and R6 are selected from hydrogen and univalent hydrocarbyl radicals and may be the same or different;
A is selected from hydrogen, univalent h~drocarbyl, or the radical Q;
provided that A i6 aryl or Q if R1 = R2 = R3 = H
and R~ is a univalent hydrocarbyl radical if A is H or a univalent hydrocarbyl radical other than an aryl radical;
n i5 0 or 1;
~ i8 selected from aryl and the radical Q provided that where both R4 and R6 are univalent hydrocarbyl radicals, n ie 1;
and Q i8 selected from the radicals -o-R7, -So-R7, -Co-R7, -So2-R7 ~nd -SR7 where R7 i8 a univalent hydrocarbyl, preferabl~ phenyl, radical.
~wo or four of radicals A, R~, R2 and R3, or two of the radicals R4, R5 and R6 may be li~ked bivalent alkylene - 8 _ - .

1~)45473 radicals. Examples of compounds containing such linked bivalent alkylene radicals inc:Lude 2 ~ ~CH2 0 I CH /C
z Z CH3 H-- ~C~ ~1~:) By the term hydrocarbyl is meant an alkyl group containing up to eight carbon atoms such as for example methyl, ethyl, isopropyl, tertiary butyl or an aryl group.
By the term aryl is meant an aryl group directly coupled through an aromatic carbon atom, for example, phenyl, biphe~ylyl, naphthyl. The groups may be substituted with inert atoms or groups, but are preferably unsubstituted.
We prefer, when using compounds of the formula ''' l L. n B
to use compounds wherein n i~ 0 and R4 = R6 = H. An example _ g _ .: , ' : .
' ': ', ~

of such a compound wherein B is aryl and n is 0 is benzyl chloride (B ~ phenyl; R4 = R6 = H; Z = Cl), which has been found to be particularly effecti~e. Another compound that may be used is a-chloro acetone (B = co-R7;
R4 = R6 = H; R7 = CH3; Z = Cl.) An example of a compound of the formNla A - C - C - Z

where A i~ the radical Q is ~-chloropropiophenone (Q = -Co-R7 where R7 = phenyl; R1 = R2 = R3 = H; and Z = Cl).
We prefer however to u~e compounds of the formula Z
H R
where A i~ hydrogen or a univalent hydrocarbyl radical.
In such compounds, because of the effect of substitution at the a carbon atom, hydrogen halide elimination, with consequent alkene formation, rather than halogen displacement, i8 favoured when the carbon atom in the a-po~ition to the halogen atom i8 secondary or, preferably, tertiary, i.e. R2 or R3 a~d preferably both are univalent hydrocarbyl radicals. ~hu~ tertiary halides _ 10 -1()45~73 such as t-butyl chloride are preferred since they more favour the elimination reaction than secondary halides such as isopropyl chloride. Eowever the cyclohexyl halides, although only secondary halides, are particularly effective, presumably because of a steric effect.
Preferred organic halides are tertiary butyl (A1 = R1 = H; R2 = R3 = methyl), and cyclohexyl (A1 = R2 = H;
R1 = R3 = bimethylene, i.e. R1 and R3 together is tetramethylene) halides.
~limination of hydrogen halide from compounds of the formula R1 R2 R5 Rl6 A - C - C - Z or R - C - C - Z

(i.e. where n = 1) is generally insensitive to nature of the halogen although the rate of elimination appears to be iodide ~ bromide > chloride. However because the price per mole of iodide and bromide is higher than that for the corresponding chloride, chlorides are preferred.
Org~ic halides containing more than one halogen atom on the same carbon atom, such as chloro~orm or methylene dichloride, are ~ot suitable for use in the present invention as they tend to give rise to a marked increase in molecular weight of the polymer, and in some cases a cross-linked intractable product. A second halogen atom ~0~5473 may however be present (as for example in 2,6-dichloroheptane) if like the first it undergoes elimination and not displacement by nucleophilic substitution.
Hitherto thermoplastic aromatic hydroxyl or thiol ended polymers have ~een prepared by washing the arom~tic polymer with aqueous acid, for example dilute acetic acid, after extraction of the polgmer from the reaction mixture in which it has been produced. ~he present invention is advantageous in that the hydroxyl or thiol ended polymer can be produced by adding the organic halide to the reaction mixture at a predetermined stage of the polymerisation reaction 90 as to terminate the reaction.
The reaction between the organic halide and the polymer may be carried out at temperatures between 50C and 300C, the temperature and speed of reaction depending on the particular halide used. Accordingly, routes and apparatus for producing thermoplastic aromatic polysulphones used or de~cribed in the above British and U.S. patent specifications may be used for the process of the present invention.
Aromatic polymers having reduced viscosity of between 0.8 and 3.0 [as measured at 25C on a solution of polymer in concentrated sulphuric acid (density 1.84 g/cm3) containing 1 g of pol~mer in 100 cm3 of ~olution] whose molecular chains comprise 1,4-phenylene, lV45473 oxygen and ketone groups and optionally either or both of 4,4'-biphenylene and sulphone groups may be made by a process which comprises heating1 at temperatures of 250C to 400C (preferably at 280C to 350C), in the presence of diaryl sulphone having the formula R8R9So2 where R8 and R9 are selected from pheryl, napthyl and biphenylyl (1) a di(alkali metal) salt of at least one bisphenol selected from ( ~ )2 (49 to 50% molar) H ~ CO ~ CO ~ OH

H ~ CO ~ C ~ OH
together with at least one compound (2) selected from i) a dihalo compound (D ~ 2co (0-51% molar) ii) a dihalo compound D ~ CO ~ CO ~ D

or D ~ CO ~ ~ C ~ D ~ (0-51% molar) optionally with (3) a dihalo compound ( ~ 2so2 (0-25~ molar) where D is F, Cl or Br, m is 1, 2 or 3; and the percentages summing to 100~. The diaryl sulphone is preferably diphenyl sulphone.

~045~73 Polymeric material produced by the present process can be extracted from the reaction mixture by methods described in those specifications except that polymer should not be heated after reaction with organic halide above 300C because of attendant risk of cross-linking and i~crease in molecular weight.
Whilst it is preferred that the organic halide is heated with polymer at or towards the end of the polymerisation, the polymer containing phenate or thiophenate end groups can be extracted from the polymerisation reaction mixture first and subsequently heated with organic halide. Such procedure may be u~eful where batches are large and only a portion is required for conversion into hydroxyl or thiol ended polymer.
Where the reaction between the pol~mer and the organic halide is performed in solution, and it is desired to recover the solvent for future use, particularly where this solvent i8 the polymerisation solvent, the organic halide is preferably a volatile compound so that it can readily be removed prior to reuse of the solvent. For - this reason org~niC halides boiling, at atmospheric pressure, below the boiliug point of the solvent and preferably below about 100C are preferred.
~he in~ention is illustrated by the following examples.

_ 14 -lU~5473 EXAMPlæS 1 T0 5 A sample of 4~(4-chlorophenyl sulphonyl) phenol (50.1065 g; 0.1865 mole) was dissol~ed in methanol (redistilled) and aqueous potassium hydroxide solution (4 normal; 46~5 cm3; 0.1869 mole) was added. The solution was evaporated to dr~ness using a rotary evaporator and the resultant solid was powdered and dried for 18 hours under vacuum (~0.001 torr) to give the A~hydrous pota~sium salt.
The dipota~si~m salt of bis-(4-hydroxyphenyl) sulphone was prepared similarly by reacting bis-(4-hydroxyphenyl) sulphone (18.0190 g; 0.0720 mole) with aqueous potassium hydroxide solution (36.0 cm3; 0.144 mole~; 4 normal).
The potassium content of the salts was determined by potentiometric titration against standard 0.1 normal aqueous hydrochloric acid.
In a 100 cm3 3-necked flask fitted with stirrer, nitrogen inlet and outlet and an air condenser were placed, potassium salt of 4~(4-chlorophenyl sulphonyl) phenol (12.2728 g = 0.04 mole), dipotassium salt of bis-(4-hydroxyphenyl) sulphone (94.4~ purity, 0.138~ g, 0.0004 mole) and diphenyl sulphone (recrystallised from isopropanol; 18.8 g, to give 40~ 801ution by weight of the ~alts). The flask was lowered into an oil bath at 250C and the stirrer started. After a period ~as shown in _ 15 -~V45473 the following table) fir~tly anhydrous pota~sium carbonate (0.25 g) and secondly an alkyl chloride were added, the latter either as gas or as li~uid from a dropping funnel.
After all the alkyl chloride (RCl) had been added, methyl chloride gas was passed through the solution. The resultant material was poured out and, after cooling, was ground up, extracted three times with boiling methanol and three times with boiling water containing 1% v/v acetic acid to give the polymer which was dried at 130C for 18 hours at 1 torr.
In a control experiment (Example 1) the polymerisation reaction proceeded as described above but after 2.5 hours at 250C the reaction mixture was allowed to cool and solidify. ~he solid mass was macerated with water and then twice with boiling water containing 1X v/v acetic acid. ~he polymer was found by nuclear magnetic resonance spectroscopy to consist of repeat unit~ having the formula ~S02-Alkyl end groups per 100 polymer repeat units were estimated and detected by nuclear magnetic resonance spectroscopy. For determination of hydroxyl end groups per 100 polymer repeat units, samples of polymers were compression-moulded at 280C for 5 minutes under a pressure of 7 MN/m2 (5 tons on a 4 inch diameter platen~;
the film~ were examined by infra-red in the range 2.5 , . . . : ~.

.

to 3 .1 llm aIld 2 . O to 2. 3 llm ancL the h~ydroxyl content estimated by comparison of the bands at 2.96 ~Lm and 2.15 ~m.

-_ 17 --~45473 _ ~ ~ ~
o I ~ ~o,l~
~ F~l J~

:~_ ~
O ~ ~ r~ ff~
. ~ O ~ q~ K~ ~ ~ h P ~ ~ K~ ~ ~ ~ U~ P
~; O O O O O ~ ~ O

~$ ~
~ ~ ~ I KO~ 0 ~

~ h u~ ~ t ~ 2 ff~
h O O r~
~ O O O O O N
i'~ O Ll~ _~ h ._ _. ~ o L

. , ':' , . ~ , .

~)45473 The results show that addition of tertiary butyl chloride and cyclohexyl chloride to the pol~merisation mixture lead to hydroxyl end groups without detectable formation of alkoxy end groups.
The purpose of adding the potassium carbonate was to ensure truly comparative re~ults: the potassium carbonate converts to phenate end groups any hydroxyl end group~ that might already be present.
In repeat experiments of Examples 3 to 5 but omitting the potassium carbonate addition similar results were obtained showing that the alkyl halide is responsible for the formation of hydroxyl end groups rather than that they are already present before aIk~l halide addition.
The methyl chloride wa~ added in Examples 3 to 5 to show that the aIkyl halide added in accordance with the invention converted all of the end groups present that could be converted: thus if any reactive end groups had remained after addition of the alkyl halide of the invention, the methyl chloride would convert them to methoxy group~ - however in Examples 3 to 5 no such methoxy end groups were found.
~XAMæ~E 6 ~he polymerisatioi te~igue as used in ~xamples 1 to 5 wa~ repeated but after ~ polymeri~ation time of

3 hours, the polymerisation ~a~ terminated by the addition 1t)45473 of benzyl chloride (0.5 ml) (no potassium carbonate was added). The reaction mixture was maintained at 250C for 30 minutes and then the polymer isolated as in Examples 1 to 5, save that no methyl chloride was introduced.
The resulting polymer contained 2.51 hydroxyl end groups per 100 polymer repeat units and had a reduced viscosity of 0.33.
Reduced viscosity (RV) of the polymers in the above Examples was measured on solutions of the polymers in dimethyl formamide at 25C containing 1 g of polymer in 100 cm3 of solution.

' ''. "" ' ' . . .
.

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Claims

The embodiments of the invention in which an exclusive property and privilege is claimed are defined as follows:

1 A surface coated with an adhesive composition comprising a thermoplastic aromatic polymer containing hydroxyl or thiol end groups made by reacting a thermo-plastic aromatic polymer containing alkali metal phenate or thiophenate end groups with at least one organic halide containing a halogen atom and at least one hydrogen atom that eliminates both the halogen atom and a hydrogen atom when in the presence of a nucleophile, rather than displacement of just the halogen atom, under the reaction conditions employed

2. A surface as claimed in Claim 1 wherein the organic halide has the formula:

or where Z is a halogen atom selected from chlorine, bromine and iodine;
R1, R2, R3, R4, R5 and R6 are selected from hydrogen, univalent hydrocarbyl radicals (which are defined as alkyl groups containing up to eight carbon atoms, and aryl groups directly coupled through an aromatic carbon atom), and may be the same or different;
A is selected from hydrogen, univalent hydrocarbyl or the radical Q;

provided that A is aryl or Q if R1 = R2 = R3 = H, and R3 is a univalent hydrocarbyl radical if A is H or a univalent hydrocarbyl radical other than an aryl radical;
n is 0 or 1;
B is selected from aryl and the radical Q;
provided that where both R4 and R6 are univalent hydrocarbyl radicals, n is 1;
and Q is selected from the radicals -OR7, - SO-R7, - CO-R7, -SO2-R7 and -SR7, where R7 is a univalent hydrocarbyl radical,

3. A surface as claimed in Claim 2 wherein R7 is phenyl.

4, A surface as claimed in Claim 2 wherein two or four of the radicals A, R1, R2 and R3, or two of the radicals R4, R5 and R6 are linked bivalent alkylene radicals.

5. A surface as claimed in Claim 2 wherein the organic halide has the formula:

6. A surface as claimed in Claim 5 wherein the organic halide is a benzyl halide.

7. A surface as claimed in Claim 2 wherein the organic halide has the formula:

and A is hydrogen or a univalent hydrocarbyl radical.

8. A surface as claimed in Claim 7 wherein at least one of R2 and R3 are univalent hydrocarbyl radicals.

9. A surface as claimed in Claim 8 wherein the organic halide is a cyclohexyl halide.

10. A surface as claimed in Claim 8 wherein both R2 and R3 are univalent hydrocarbyl radicals.

11. A surface as claimed in Claim 10 wherein the organic halide is a t-butyl halide.

12. A surface as claimed in Claim 1 wherein the organic halide is a chloride.

13. A surface as claimed in Claim 1 wherein the organic halide has a boiling point, at atmospheric pressure, of less than 100°C.

14. A surface as claimed in Claim 1 wherein the thermoplastic aromatic polymer comprises repeating units of the formula -Ar-X- in which Ar is a bivalent aromatic radical and X is -CO- or -SO2- and each may vary from unit to unit in the polymer chain.

15. A surface as claimed in Claim 14 in which the aromatic polymer contains at least some units of the structure:

in which Y is oxygen or sulphur or the residue of an aromatic diol.

16. A surface as claimed in Claim 15 wherein the aromatic polymer has repeating units selected from the formulae and where Y is oxygen or sulphur.

17. A surface as claimed in Claim 15 wherein the aromatic polymer has repeating units selected from the formulae and together with units of the formula where Y is oxygen or sulphur.

18. A surface as claimed in Claim 15 wherein the aromatic polymer has repeating units selected from the formulae and together with units of the formula where Y is oxygen or sulphur.

19. A surface as claimed in Claim 15 wherein the aromatic polymer has repeating units selected from the formulae:

and together with units of the formulae:

and where Y is oxygen or sulphur.

20. A surface as claimed in Claim 1 wherein the organic halide is added to the reaction mixture used to produce the aromatic polymer so as to terminate polymerisation.

21. A surface as claimed in Claim 1 wherein the reaction between the organic halide and the polymer is performed at a temperature in the range 50 to 300°C.

22. A surface as claimed in Claim 1 wherein the reaction of the organic halide and the aromatic polymer is performed in the presence of an organic solvent.

23. A surface as claimed in Claim 8 wherein the polymer is prepared in the presence of an organic solvent and the reaction of the polymer with the organic halide is performed in the presence of the polymerisation solvent.

24. A surface as claimed in Claim 22 wherein the solvent is recovered and reused and wherein the organic halide has a boiling point, at atmospheric pressure, below the boiling point of the organic solvent.

25. A surface as claimed in Claim 1 wherein the aromatic polymer is prepared by polycondensation of a molar excess of at least one alkali metal bisphenate or bisthiophenate, with at least one dihalobenzenoid compound in which the halogen atoms are activated by inert electron withdrawing groups.

26. A surface as claimed in Claim 1 wherein the aromatic polymer is prepared by polycondensation of at least one alkali metal halophenate or halothiophenate, wherein the halogen atoms are activated by inert electron withdrawing groups in the presence of an alkali metal bisphenate or bisthiophenate.