POLYMERIC MATERIAL
The invention relates to a process for making a polymeric material and a polymeric
material per se. Particularly, although not exclusively, the invention relates to a process for
making polyetheretherketone (PEEK) and a novel PEEK per se.
PEEK polymers are known to have a range of outstanding properties, including
excellent heat resistance, chemical resistance, dimensional stability and mechanical
properties. They are utilised in a wide range of demanding applications, including, amongst
others, aerospace, automotive, electronics, deep sea oil and gas, and nuclear industries, as
well as being approved for a wide range of medical uses.
A number of companies currently manufacture PEEK polymers (including Evonik
Industries, Solvay and Applicant), and currently all of these manufacturers rely on a
nucleophilic reaction process (as disclosed generally in European Patent Publication EP1 879)
whereby 1,4-dihydroxybenzene (HQ) is reacted with 4,4'-difluorobenzophenone (BDF) at
elevated temperature in the presence of a suitable high boiling solvent (typically
diphenylsulfone or sulfolane) and typically in the presence of a carbonate base in order to
promote the polymerisation reaction.
Alternative, electrophilic routes, to PEEK polymers are also possible (see for example
European patents EP1 263836B and EP1 17031 8B) although such routes are believed not to
be used to produce PEEK commercially.
There are a number of significant problems with the standard industrial nucleophilic
process to PEEK polymers which will be well known to those skilled in the art and include:
The process is typically run batch-wise, with all reagents present in the reactor at the
start of reaction .
In order to control molecular weight, precise control of the ratio of 1,4-dihydroxybenzene
and 4,4'-difluorobenzophenone monomers is required. Whilst this is straightforward on
a small scale, on an industrial scale this precise control can be a problem , meaning that
control of polymer molecular weight can be difficult.
Both monomers need to be of exceptionally high purity in order to produce high quality
PEEK polymer. Very small changes in the purity of either monomer can have a
dramatic and undesirable effect on the resultant polymer properties, as well as making
the polymerisation reaction difficult to control.
Both monomers are susceptible to being lost from the reaction mixture by sublimation at
elevated temperatures, meaning that precise control of monomer ratio can be difficult.
Two moles of base (typically carbonate) are required to generate every mole of PEEK
polymer repeat unit.
The nucleophilic process generates two moles of C0 2 gas for every polymer repeat unit
which is generated. If not controlled, this gas evolution can represent a significant
process safety hazard.
Control of gas evolution rate results in extended polymerisation times.
The risk of the reaction mixture foaming means that the polymerisation vessels have to
be run with a significant headspace present - thus reducing plant efficiency.
As molecular weight increases, the oligomers which are formed have the potential to
crystallise in the reactor - resulting in poor heat transfer and, consequently, extended
reaction times. Because of this effect, there is essentially a limit on how concentrated
the polymerisation reaction can be run.
The ,4-dihydroxybenzene monomer which is used is known to have significant health
hazards associated with it (category 3 mutagen).
k) The ,4-dihydroxybenzene monomer is very sensitive to reaction with atmospheric
oxygen, meaning that the polymerisation process has to be rigorously inerted with
nitrogen.
I) Every mole of polymer repeat unit which is generated also results in the generation of
two moles of fluoride salt bi-product. This has to be removed in a subsequent process,
generating significant quantities of effluent.
It is an object of the preferred embodiments of the present invention to address at least
some of the aforementioned problems.
In addition, commercially available PEEK has a Tg of 43 °C and a Tm of about 340 °C.
For many applications, however, it is desirable to maintain relatively high Tg but lower the Tm
so as to facilitate melt processing. It is an object of preferred embodiments of the invention to
address this problem .
Furthermore, it is desirable for PEEK polymers produced to be as light in colour as
possible, since darker polymers may be perceived to be of lower quality (e.g. as being
relatively impure). Lighter coloured PEEK is generally preferred for applications where the
aesthetics of the article are important. It is an object of preferred embodiments to address this
problem .
According to a first aspect of the invention, there is provided a process for producing a
polymeric material having a repeat unit of formula
the process comprising polycondensing a monomer of structure
Thus, in the process, monomers of structure II are polycondensed with one another to
produce the polymeric material of formula I .
Said process is preferably carried out in the presence of one or more carbonates. The
process is preferably carried out in the presence of alkali metal carbonate. Said process is
preferably carried out in the presence of one or more carbonates which preferably include
sodium carbonate, which may, optionally, be in combination with potassium carbonate.
The total mol% of carbonates used in the process ( i .e. the total number of moles of
carbonates used in the process divided by the total number of moles of hydroxy monomer(s)
used (especially said monomer of structure II), expressed as a percentage) is suitably at least
00 mol%.
The total mol% of carbonates may be greater than 00 mol%. It may be less than 05
mol%.
The mol% of sodium carbonate used in the process (i.e. the moles of sodium carbonate
used in the process divided by the moles of said monomer of structure II) may be at least 90
mol%, preferably at least 92 mol%, more preferably at least 95 mol%.
The total mol% of sodium carbonate and potassium carbonate used in the process (i.e.
the sum of the moles of sodium carbonate and potassium carbonate used in the process
divided by the moles of said monomer of structure II) is preferably at least 100 mol% and is,
more preferably, greater than 00 mole%. It may be in the range 00 to 05 mol%.
The mol% of carbonates (which term is intended to encompass carbonate (C03
~) and
bicarbonate (HC03
~)) other than sodium carbonate and potassium carbonate used in the
process is preferably less than 5 mol%, more preferably less than 1 mol% (again related to
the moles of said monomer of structure II).
Preferably, the only carbonates used in the process are sodium carbonate and
potassium carbonate.
In the process, alkali metal fluoride (which suitably comprises sodium fluoride and may
comprise both sodium fluoride and potassium fluoride when sodium and potassium carbonate
are used in the process, as is preferred) is suitably produced as a bi-product of the
polycondensation. The ratio of the total number of moles of alkali metal fluoride produced in
the process divided by the number of moles of repeat units of formula I is suitably in the range
0.9 to .1 and is preferably about .
In the process, carbon dioxide is suitably produced as a bi-product of the
polycondensation. The ratio of the total number of moles of carbon dioxide produced in the
process divided by the number of moles of repeat units of formula I is suitably in the range 0.9
to 1.1, and is preferably about 1
Said polymeric material having a repeat unit of formula I may include at least 90 mol%,
suitably at least 95 mol%, preferably at least 98 mol%, especially at least 99 mol% of repeat
units of formula I.
Said polymeric material having a repeat unit of formula I may include at least 90 wt%,
suitably at least 95 wt%, preferably at least 98 wt% of repeat units of formula I .
Said polymeric material having a repeat unit of formula I preferably includes fluorine
moieties at its ends. Preferably at least 90 % (more preferably about 00 %) of the number of
end groups in said polymeric material comprise fluorine atoms.
In the process, the ratio of the number of moles of monomer of formula I I divided by the
total number of moles of monomers used in the process is preferably in the range 0.90 to 1,
more preferably in the range 0.95 to 1, especially in the range 0.98 to 1. When said ratio is not
equal to 1, the process may include introducing an additional monomer into the process. Said
additional monomer preferably does not include an hydroxyl moiety. Said additional monomer
preferably includes at least two halogen atoms, especially two fluorine atoms. Said additional
monomer is preferably a difluoro-compound. It is preferably arranged to react with and replace
the OH moieties of monomer of formula I I . It is preferably arranged to end-cap the polymeric
material formed in the process. As a result, ends of the polymeric material of formula I
suitably include fluorine atoms which suitably help to stabilise the polymeric material.
In the process, it is preferred that no hydroxyl group-containing monomer is used other
than said monomer of structure I I . Said process preferably does not comprise use of a
hydroquinone.
Said additional monomer preferably includes one or more phenyl moieties. Said
additional monomer suitably includes at least one phenyl moiety, substituted in the 4-position,
suitably with a fluorine atom. Said additional monomer may include two phenyl moieties. In
this case, preferably both of said two phenyl moieties are substituted by fluorine atoms,
suitably in the 4-positions. Said two phenyl moieties may be separated by a ketone moiety.
Said additional monomer is preferably 4,4'- difluorobenzophenone.
Said process suitably include polycondensing 95 to 00 wt% (preferably 97.5 to 99.5
wt%) of said monomer of structure I I in the presence of 0 to 5 wt% (preferably 0.5 to 2.5 wt%)
of said additional monomer.
In a preferred embodiment, said process is carried out in the presence of a solvent
(which is suitably a polar aprotic organic solvent). Advantageously, the ratio of the total
number of moles of monomers used in the process divided by the total number of moles of
solvent may be greater than 0.3, suitably greater than 0.4. The ratio may be in the range 0 .1
to 0.8, for example in the range 0.3 to 0.6.
Said solvent may be of formula
where W is a direct link, an oxygen atom or two hydrogen atoms (one attached to each
benzene ring) and Z and Z', which may be the same or different, are hydrogen atoms or
phenyl groups. Examples of such aromatic sulphones include diphenylsulphone,
dibenzothiophen dioxide, phenoxanthin dioxide and 4-phenylsulphonyl biphenyl.
Diphenylsulphone is a preferred solvent.
The process is preferably carried out under substantially anhydrous conditions. In the
process, the compound of formula I I is suitably contacted with carbonate of the type described
in the presence of said solvent, especially diphenylsulphone. Polymerisation is suitably
effected at a temperature within the range 15 C to 400 °C. In the process, the reactants are
suitably heated up to a maximum temperature which may be greater than 300 °C, for example
in the range 300 °C to 350 °C. The process may be carried out without holding the temperature
at any temperature less than 300 °C. Heat up, to a temperature in excess of 300 °C, may be
substantially continuous.
Advantageously, preferably no blanket of inert gas (e.g. N2) is introduced and/or used in
the process, for example to minimise oxidation. The process may be carried out under
ambient atmospheric conditions.
The process may be carried out in a receptacle and, advantageously, the receptacle
may be run fuller than in prior art processes for production of said polymeric material because
only half the amount of carbon dioxide is produced compared to prior art processes. In the
process the maximum amount of liquid in the receptacle during the process may fill at least
80%, preferably at least 85% of the volume of the receptacle. Said volume may be less than
95%.
The polymeric material of the first aspect preferably has a Tm of less than 340 °C. It
may have a Tg in the range 142 to \ 44°C. Said polymeric material of the first aspect may
include any of the preferred features described according to the second embodiment.
According to a second aspect of the invention, there is provided a polymeric material
which comprises a repeat unit of formula I, wherein said polymeric material has a Tm of less
than 340 ° and a Tg in the range 42 to 44 € .
Preferred features of the polymeric material of the first and second aspects are
described below.
Preferably, the only repeat units in said polymeric material of formula I are repeat units
which include phenyl moieties (especially unsubstituted phenyl moieties), ether moieties and
ketone moieties. Preferably, the only repeat units in said polymeric material of formula I are
repeat units which comprise unsubstituted phenyl moieties separated by ether or ketone
moieties. In said repeat units, preferably the ratio of the number of ether moieties divided by
the number of ketone moieties is 2 ; and the ratio of the sum of the number of ether moieties
and ketone moieties divided by the number of phenyl moieties is 1.
Said polymeric material having a repeat unit of formula I may include at least 90 mol%,
suitably at least 95 mol%, preferably at least 98 mol%, especially at least 99 mol% of repeat
units of formula I.
Said polymeric material having a repeat unit of formula I may include at least 90 wt%,
suitably at least 95 wt%, preferably at least 98 wt% of repeat units of formula I .
Said polymeric material having a repeat unit of formula I preferably includes fluorine
moieties at its ends. Preferably at least 90% (more preferably at least 99%, especially about
00%) of the number of end groups in said polymeric material comprise fluorine atoms.
Said polymeric material may have a Tm (assessed as described hereinafter) of less than
339 °C, suitably less than 338 °C, preferably less than 337 € . The Tm may be in the range
332 °C to 339 °C, suitably in the range 333 °C to 337°C.
The difference (Tm-Tg) between the Tm and Tg of said polymeric material may be in the
range 89-1 95 °C.
In a preferred embodiment, said polymeric material has a Tg in the range 142 - 144°0,
a Tm in the range 333 °C to 337 and the difference between the Tm and Tg is in the range
189 °C to 195 °C.
Said polymeric material may have a crystallinity measured as described hereinafter of at
least 25%. Crystallinity may be less than 38%.
Said polymeric material suitably has a melt viscosity (MV) of at least 0.06 kNsm 2 ,
preferably has a MV of at least 0.08 kNsm 2 , more preferably at least 0.085 kNsm 2 , especially
at least 0.09 kNsm 2 . MV of said polymer material is suitably measured using capillary
rheometry operating at 400 °C at a shear rate of 1000s 1 using a tungsten carbide die, 0.5mm x
3.1 75mm. Said polymer material may have a MV of less than 1.00 kNsm 2 , suitably less than
0.8 kNsm 2 .
Said polymeric material may have a tensile strength , measured in accordance with
IS0527 of at least 40 MPa, preferably at least 60 MPa, more preferably at least 80 MPa. The
tensile strength is preferably in the range 80-1 10 MPa, more preferably in the range 80-1 00
MPa.
Said polymeric material may have a flexural strength, measured in accordance with
IS01 78 of at least 130 MPa. The flexural strength is preferably in the range 135-1 80 MPa,
more preferably in the range 140-1 50 MPa.
Said polymeric material may have a flexural modulus, measured in accordance with
IS01 78 of at least 2 GPa, preferably at least 3GPa. The flexural modulus is preferably in the
range 3.0-4.5 GPa, more preferably in the range 3.0-4.0 GPa.
Said polymeric material may be in the form of pellets or granules, wherein the pellets or
granules include at least 95wt%, preferably at least 99wt%, especially about 100wt% of said
polymeric material. Pellets or granules may have a maximum dimension of less than 10mm,
preferably less than 7.5mm, more preferably less than 5.0mm.
Said polymeric material suitably has L* , assessed as described hereinafter, of at least
65, preferably at least 66, more preferably at least 67. The L* may be less than 78. In some
embodiments, it may be less than 75. L* is suitably in the range 66 to 782.
According to a third aspect of the invention, there is provided a pack comprising a
polymeric material as described herein .
Said pack may include at least 1kg, suitably at least 5kg, preferably at least 10kg, more
preferably at least 14kg of material of which at least a part is made up of said polymeric
material. Said pack may include 1000kg or less, preferably 500 kg or less of said material.
Preferred packs include 10 to 500 kg of said material.
Said pack may include at least 1kg, suitably at least 5kg, preferably at least 10kg, more
preferably at least 14kg of a said polymeric material. Said pack may include 1000kg or less,
preferably 500kg or less of said polymeric material . Preferred packs include 10 to 500 kg of a
said polymeric material.
Polymeric material in said pack may be in powder or granular form .
Said pack may comprise packaging material (which is intended to be discarded or re
used) and a desired material (which suitably comprises said polymeric material). Said
packaging material preferably substantially fully encloses said desired material. Said
packaging material may comprise a first receptacle, for example a flexible receptacle such as a
plastics bag in which said desired material is arranged. The first receptacle may be contained
within a second receptacle for example in a box such as a cardboard box.
Any feature of any aspect of any invention or embodiment described herein may be
combined with any feature of any aspect of any other invention or embodiment described
herein mutatis mutandis.
Specific embodiments of the invention will now be described, by way of example, with
reference to the accompanying figures, in which :
Figure 1 is a polymerisation profile of a process for producing PEEK from a single
monomer and an equivalent profile for a standard process for producing PEEK; and
Figure 2 illustrates gas evolution during the process for producing PEEK from a single
monomer and the equivalent gas evolution from a standard process for producing PEEK.
The following materials are referred to hereinafter:
4-fluoro-4'-(4-hydroxyphenoxy) benzophenone synthesised as described in Example 4 ,
referred to as "FHPB".
In general terms the preparation of polyetheretherketone (PEEK) may be undertaken by
polycondensation of a single monomer (4-fluoro-4'-(4-hydroxyphenoxy) benzophenone) in
diphenylsulphone (DPS) solvent and in the presence of sodium carbonate and potassium
carbonate as summarized in the scheme below.
A small amount of 4,4'-difluorobenzophenone (BDF) may be included in the
polymerisation mixture (or may be added during the polymerisation) to control the rate of
polymerisation, act as an end stopper and/or to ensure the PEEK polymer is fluorine ended.
Compared to the process described in EP 879 which involves polycondensation of BDF
and hydroquinone (HQ), use of the single monomer may be advantageous for at least the
following reasons:
(a) The single monomer process only requires half as much carbonate to effect the
reaction , meaning that only half as much sodium fluoride (which needs to be removed in
subsequent processing) is formed.
(b) In the process of EP 879, molecular weight of the PEEK is controlled by precise control
of the ratio of BDF to HQ used. This can be difficult, particularly on an industrial scale,
meaning that molecular weight control can be difficult. There is no monomer ratio to
control in the single monomer process.
(c) In the process of EP 879, the BDF and HQ monomers need to be of very high purity in
order to produce high quality PEEK polymer and small changes in monomer purity can
have dramatic effects on resultant polymer properties. Purity is less critical with the
single monomer process.
(d) In the process of EP 879, the BDF and HQ are susceptible to being lost from the
reaction mixture by sublimation at elevated temperatures, meaning that precise control
of the BDF:HQ ratio can be difficult. This is not an issue with use of a single monomer
which is less susceptible to sublimation in any event.
(e) In the process of EP 879, equimolar amounts of carbonates (based on the moles of
HQ) are required and two equivalents of carbon dioxide are produced for every PEEK
unit. Holds are introduced into the process to control gas evolution but there is still a
risk of foaming meaning that polymerisation vessels are run with a significant head
space (as much as 30% headspace). Both of these lead to reduced plant efficiency.
Advantageously, the single monomer process produces half as much carbon dioxide
and, therefore, efficiency may be significantly improved.
(f) In the process of EP 879, the necessary holds in the process lead to production of
greater levels of oligomeric material which tends to crystallise in the polymerisation
vessel resulting in poor heat transfer and, consequently, extended reaction times.
Because of this there is a limit on how concentrated the polymerisation reaction can be
run. Advantageously, the single monomer process may be run without holds. In
addition, use of higher concentration means that more polymer can be made per batch,
increasing plant capacity.
(g) The single monomer process produces lighter-coloured polymer compared to that
produced using the process of EP 879.
Further details on the process are provided below.
Example 1 - General method for preparing PEEK using single monomer
DPS ( 32.0g, 0.61 6 mol), FHPB (92.49g, 0.300 mol) and BDF (0.87g, 0.004 mol) were
charged to a 500ml flange flask equipped with an anchor type agitator, overhead stirrer, gas
inlet and air condenser. After inerting with nitrogen, (a step which is not required but which was
included so as to be comparative with Example 3), the mixture was heated to 160 with
stirring at 70rpm . Sodium carbonate ( 5.98g, 0 .15 1 mol) and potassium carbonate (0.42g,
0.003 mol) was slowly added and the resulting mixture heated at 1°C/min to 3 1 °C. The
polymerisation mixture was maintained at 3 10°C until the desired torque rise was reached. At
this point the molten toffee was poured into a foil tray, allowed to cool, milled and washed with
2 litres of acetone and then with warm water at a temperature of 40 - 5 °C until the
conductivity of the waste water was < 2m . The resulting polymer powder was dried in an air
oven for 12 hours at 120°C.
Example 2 (Comparative Example) - General method for preparing PEEK using sodium salt of
single monomer
In this comparative example, PEEK was prepared using the sodium salt of FHPB as
illustrated in the scheme below.
FHPB was reacted with an equimolar amount of sodium hydroxide to produce the
sodium salt which could then be polymerised in DPS without any further sodium carbonate.
In the process, DPS ( 1 32.0g, 0.61 6 mol) was charged to a 500ml flange flask equipped
with an anchor type agitator, overhead stirrer, gas inlet and air condenser. After inerting with
nitrogen the mixture was heated to 290 °C with stirring at 70rpm . The FHPB sodium salt
(99.08g, 0.300 mol) was added over 10 minutes whilst maintaining the contents temperature at
290-300 °C. When the addition was complete potassium carbonate (0.42g, 0.003 mol) and
BDF (0.87g, 0.004 mol) were added . The resulting mixture was heated to 3 10°C and
maintained at this temperature until the desired torque rise was reached. If required, further
potassium carbonate (0.21 g , 0.002 moles) was added to increase the rate of polymerisation.
At this point the molten toffee was poured into a foil tray, allowed to cool, milled and washed
with 2 litres of acetone and then with warm water at a temperature of 40 - 5 °C until the
conductivity of the waste water was < 2m8 . The resulting polymer powder was dried in an air
oven for 2 hours at 20°C.
Example 3 (Comparative Example) - General method for preparing PEEK using BDF and HQ
as described in EP 879
DPS ( 1 32.0g, 0.61 6 mol), HQ (33.03g , 0.300 mol) and BDF (66.33g, 0.304 mol) were
charged to a 500ml flange flask equipped with an anchor type agitator, overhead stirrer, gas
inlet and air condenser. After inerting with nitrogen the mixture was heated to 160 °C with
stirring at 70rpm. When the mixture was molten , sodium carbonate (31 .96g, 0.302 mol) and
potassium carbonate (0.83g, 0.006 mol) was slowly added and the resulting mixture heated at
1°C/m\n to 3 °C. The polymerisation mixture was maintained at 3 10°C until the desired
torque rise was reached. The reaction mixture was then poured into a foil tray, allowed to cool,
milled and washed with 2 litres of acetone and then with warm water at a temperature of 60-
7 °C until the conductivity of the waste water was < 2m8 . The resulting polymer powder was
dried in an air oven at 120°C.
Example 4 Synthesis of 4-fluoro-4'-(4-hvdroxyphenoxy) benzophenone monomer (FHPB)
Aluminium chloride (333.35g, 2.5mol) and 1,2-dichlorobenzene (650 ml) and were
charged to a nitrogen inerted 1L jacketed reactor flask equipped with anchor style agitator,
overhead stirrer, temperature probe, addition funnel and a condenser with an outlet to a
caustic scrubber.
The reaction was heated to 60 °C and 4-phenoxyphenol ( 1 86.21 g , 1.0mol) was added
portion wise. When the addition was complete 4-fluorobenzoylchloride ( 1 58.56g, (LOmol) was
added drop-wise over 120 minutes. The reaction mixture was heated at 1°C/min to 90 °C and
maintained at this temperature for 60 minutes.
The brown coloured solution was then carefully quenched onto stirred cold water and
the biphasic mixture was allowed to exotherm to °C in order to solubilise the monomer in the
organic phase. The aqueous phase was removed and the organic phase washed with
demineralised water (3 x 500ml) to remove aluminium salts and excess acidity.
The organic phase was cooled at 1°C/m\n to °C and the crystalline solid filtered off and
washed with 60/80 petroleum ether (400ml).
The crude product was dissolved in hot toluene (5ml per 1g of product), stirred with
activated carbon (2% w/w) and then hot filtered to remove the carbon. The clear yellow filtrate
was slowly cooled to °C, filtered , washed with toluene (200ml), 60/80 petroleum ether (400ml)
and dried under vacuum at 60 °C. The product was 99.98% pure and had a melting point of
142.3 € .
Assessments and results for Examples , 2 and 3 are detailed and discussed below.
Note that references to "standard PEEK" and "standard PEEK process" refer to PEEK made
as described in Example 3 .
. Referring to Figure , the set point temperature and contents temperature substantially
overlie one another. More importantly, it will be noted that the torque for the Example 1
process increases steadily once the polymerisation temperature has been reached with
no increase in torque during the heat up to the polymerisation temperature. However,
for the standard PEEK process, the molecular weight of the polymer increases rapidly
and is difficult to control once the polymerisation temperature is reached. Also, the rise
and decrease in torque during heat-up, illustrates that oligomers formed in the reaction
have come out of solution. Such a crystallised material can detrimentally affect the
properties of the PEEK produced. This is in contrast to the torque rise for the standard
PEEK process which illustrates the greater difficulty in controlling this process.
2. The gas evolution of the Example 1 process was studied and compared with the
standard PEEK process. In the Example 1 process significant gas evolution began to
occur when the temperature of the contents reached 200 °C as opposed to 80 for the
standard PEEK process. For the Example 1 process only half the amount of gas was
evolved and at lower peak flow rates than for the standard PEEK process.
3 . The process of Example 1 was used to produce PEEK of relatively high MV (e.g.
MV=0.56 KNsm 2 and 0.57 KNsm 2 where MV is measured at 400 °C using a tungsten
carbide die of dimensions 0.5mmx3.1 75mm at a shear rate of 000s .
4 . A DSC analysis was undertaken on polymers made as described in Example . A DSC
method has been used to evaluate the crystallinity and other characteristics of polymers
of Example 1 using a Mettler Toledo DSC1 Star system with FRS5 sensor.
The Glass Transition Temperature (Tg),crystallisation temperature (Tc) and the Melting
Temperature (Tm) were determined using the following DSC method.
A dried sample of each polymer was compression moulded into an amorphous film, by
heating 7g of polymer in a mould at 400 °C under a pressure of 50bar for 2 minutes, then
quenching in cold water producing a film of dimensions 20 x 20mm, with a thickness in
the region of 0.20mm . An 8mg plus or minus 3mg sample of each film was scanned by
DSC as follows:
Step 1 Perform and record a preliminary thermal cycle by heating the sample from
30°C to 400°C at 20°C /min.
Step 2 Hold for 5 minutes.
Step 3 Cool at 20°C/min to 30°C and hold for 5mins.
Step 4 Re-heat from 30°C to 400°C at 20°C/min, recording the Tg, Tc and Tm,
From the DSC trace resulting from the scan in step 4 , the onset of the Tg was obtained
as the intersection of the lines drawn along the pre-transition baseline and a line drawn
along the greatest slope obtained during the transition. The Tm was the temperature at
which the main peak of the melting endotherm reaches a maximum. Tc is measured as
the maximum point of the crystallisation peak on the 2nd heat/cool cycle. The polymer
was subjected to three repeat cycles, to provide an indication of the thermal stability and
quality of the polymer. Cycle 1 also ensures any thermal history in the polymer has
been erased. Generally, values quoted for Tm etc. are those taken from Cycle 2 .
The Heat of Fusion for melting (DHiti) was obtained by connecting the two points at
which the melting endotherm deviates from the relatively straight baseline. The integrated
area under the endotherm as a function of time yields the enthalpy (mJ) of the melting
transition : the mass normalised heat of fusion is calculated by dividing the enthalpy by the
mass of the specimen (J/g). The level of crystallisation (%) is determined by dividing the Heat
of Fusion of the specimen by the Heat of Fusion of a totally crystalline polymer, which for
polyetheretherketone is 30J/g.
Results for polymers produced (referred to as Examples 1a , 1b and 1c) made as
described in Example 1 are provided in Table 1.
Table 1
Cycle 1 Cycle 2 Cycle 3
Example
T m ) T c ) T ) T m C) T c C) X (%) T m(°C) T c )
1a) 335.5 265.7 143.8 335.5 265. 1 29.8 335.6 264.8
1b) 335. 1 283.9 143.8 336.0 283. 1 27.6 335.7 282.6
1c) 334.2 277.2 144.2 334.5 265.3 27.0 334.3 262.8
The peak melting point value for commercially available PEEK made using a standard
PEEK process is approximately 340 . Thus, the Example 1 process leads, advantageously,
to a lower Tm (of approximately 335 °C).
5 . Measurement of PEEK colour is made on a thin crystalline film by a Minolta
Chromameter CR400.
PEEK powder (made as described in Examples 1 and 3 with different MVs) is melted
and pressed at 400 °C and 5 tonnes within a 12cm x 12cm aluminium foil frame, which
itself is between two aluminium foil plates, and cooled to 15 C for 10 minutes. This
produces a crystalline film of 0.25-0.30mm thickness.
The Chromameter CR400 is pressed onto the film and the trigger pressed so that an
L*a*b* colour measurement is made. This process is repeated on a different part of the
film. The difference is L* values must be < 1 .6 for a reliable result. An average of the two
readings is taken to generate the L* value.
Results of colour measurements are provided below
The above table confirms that the process of Example 1 produces lighter (i.e. higher L* )
compared to the standard PEEK process of Example 3 . The process of Example 2 was
found to produce relatively dark polymers which , on the basis of a simple visual
assessment, clearly had lower L* than both Example 1 and Example 3 polymers.
6 . A Jasco V-630 dual beam spectrophotomer was used to measure absorbance with 1cm
path length glass cells. Concentrated Sulphuric acid (density 1.84g/cm 3 ) was charged to
both the reference and sample cells and the machine zeroed. The sample cell was then
charged with a solution of respective polymers in sulphuric acid ( 1% w/v solution). The
UV spectrum was recorded from 600 to 500nm and the absorbance at 550nm was
measured.
The relatively low absorbance of the polymer illustrates that it has low chain branching
and is a high quality polymer.
Thus, it should now be appreciated that the process of Example 1 can be used to
produce high quality, relatively light coloured polymers having a lower Tm than those
produced using a standard PEEK process. Furthermore, the process of Example 1 is
advantageous over the standard PEEK process for reasons given herein.
The invention is not restricted to the details of the foregoing embodiment(s). The
invention extends to any novel one, or any novel combination, of the features disclosed
in this specification (including any accompanying claims, abstract and drawings), or to
any novel one, or any novel combination, of the steps of any method or process so
disclosed.
Claims
. A process for producing a polymeric material having a repeat unit of formula
the process comprising polycondensing a monomer of structure
2 . A process according to claim , wherein said process is carried out in the presence of
alkali metal carbonate.
3 . A process according to claim 1 or claim 2 , wherein the ratio of the total number of moles
of alkali metal fluoride produced in the process divided by the number of moles of repeat units
of formula I is in the range 0.9 to . .
4 . A process according to any preceding claim , wherein the ratio of the total number of
moles of carbon dioxide produced in the process divided by the number of moles of repeat
units of formula I is in the range 0.9 to . .
5 . A process according to any preceding claim , wherein said polymeric material includes at
least 90 mol% of repeat units of formula I .
6 . A process according to any preceding claim , wherein said polymeric material includes
fluorine moieties at its ends.
7 . A process according to any preceding claim , wherein, in the process, the ratio of the
number of moles of monomer of formula II divided by the total number of moles of monomers
used in the process is in the range 0.90 to .
8 . A process according to any preceding claim , wherein the process includes introducing
an additional monomer into the process, wherein said additional monomer does not include an
hydroxyl moiety and includes at least two fluorine atoms.
9 . A process according to claim 8 , wherein said additional monomer includes at least one
phenyl moiety, substituted in the 4-position, with a fluorine atom .
10 . A process according to claim 8 or claim 9 , wherein said additional monomer is 4,4'-
diflourobenzophenone.
11. A process according to any of claims 8 to 10 , wherein said process includes
polycondensing 95 to 100 wt% of said monomer of structure II in the presence of 0 to 5 wt% of
said additional monomer.
12 . A process according to any preceding claim , wherein said process is carried out in the
presence of a solvent of formula
where W is a direct link, an oxygen atom or two hydrogen atoms and Z and Z', which may be
the same or different, are hydrogen atoms or phenyl groups.
13 . A process according to any preceding claim, wherein the process is carried out without
holding the temperature at any temperature less than 300 °C.
14 . A process according to any preceding claim, wherein no blanket of inert gas (e.g . N2) is
introduced and/or used in the process.
15 . A process according to any preceding claim, wherein the process is carried out under
ambient atmospheric conditions.
16 . A process according to any preceding claim , wherein the process is carried out in a
receptacle and the maximum amount of liquid in the receptacle during the process fills at least
80% of the volume of the receptacle.
17 . A polymeric material which comprises a repeat unit of formula
wherein said polymeric material has a Tm of less than 340 °C and a Tg in the range 142 to
144°C.
18 . A material according to claim 17 , wherein the only repeat units in said polymeric material
of formula I are repeat units which include phenyl moieties, ether moieties and ketone
moieties.
19 . A material according to claim 17 or claim 18 , wherein said polymeric material includes at
least 95 mol% of repeat units of formula I .
20. A material according to any of claims 17 to 19 , wherein said polymeric material includes
fluorine moieties at its ends.
2 1. A material according to any of claims 17 to 20, wherein said polymeric material has a
Tm of less than 339 °C.
22. A material according to any of claims 17 to 2 1, wherein said polymeric material has a Tg
in the range 142 °C-1 44°C, a Tm in the range 333 °C to 337°C and the difference between the
Tm and Tg is in the range 189 °C to 195 °C.
23. A material according to any of claims 17 to 22, wherein said polymeric material has a
crystallinity of at least 25%.
24. A material according to any of claims 17 to 23, wherein said polymeric material has a
melt viscosity (MV) in the range 0.06 kNsm 2 to 1.00 kNsm 2.
25. A material according to any of claims 17 to 24, wherein said polymeric material has L* of
at least 65.
26. A pack comprising a polymeric material according to any of claims 17 to 25.