Note: Descriptions are shown in the official language in which they were submitted.
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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
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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
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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.
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~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
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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
13
~so2~o~ f~o-
CH3
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
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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.
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For the elimination reaction to be favoured the
organic halide should preferably have the formula
R1 R2 R R6
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
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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
R5 R6
''' l
R4- C - C-Z
L. n B
to use compounds wherein n i~ 0 and R4 = R6 = H. An example
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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
R1 R2
A - C - C - Z
1 13
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
R1 R2
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
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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
H R3 H B
(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
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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,
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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.
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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.
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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
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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
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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.
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_ ~ ~ ~
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
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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
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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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