U.S. patent application number 13/125523 was filed with the patent office on 2011-09-01 for process for preparing a poly(aryl ether ketone) using a high purity 4,4'-difluorobenzophenone.
This patent application is currently assigned to SOLVAY ADVANCED POLYMERS, L.L.C.. Invention is credited to Chantal Louis.
Application Number | 20110213115 13/125523 |
Document ID | / |
Family ID | 41445399 |
Filed Date | 2011-09-01 |
United States Patent
Application |
20110213115 |
Kind Code |
A1 |
Louis; Chantal |
September 1, 2011 |
Process for preparing a poly(aryl ether ketone) using a high purity
4,4'-difluorobenzophenone
Abstract
The present invention describes a process for preparing a
poly(aryl ether ketone) by reacting a nucleophile with
4,4'-difluorobenzophenone (4,4'-DFBP) that is improved through the
use of 4,4'-DFBP that meets one or more particular purity
conditions. Also described are improved poly(aryl ether ketone)
produced using the invention 4,4'-DFBP. Amounts of
2,4'-difluorobenzophenone (2,4'-DFBP), 4-monofluorobenzophenone
(4-FBP), chlorine, and monochloromonofluorobenzophenone in
4,4'-DFBP are discussed.
Inventors: |
Louis; Chantal; (Alpharetta,
GA) |
Assignee: |
SOLVAY ADVANCED POLYMERS,
L.L.C.
Alpharetta
GA
|
Family ID: |
41445399 |
Appl. No.: |
13/125523 |
Filed: |
October 23, 2009 |
PCT Filed: |
October 23, 2009 |
PCT NO: |
PCT/EP09/64008 |
371 Date: |
April 21, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61108096 |
Oct 24, 2008 |
|
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61108097 |
Oct 24, 2008 |
|
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61140205 |
Dec 23, 2008 |
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Current U.S.
Class: |
528/126 ;
528/125 |
Current CPC
Class: |
C08G 65/4087 20130101;
C07C 45/78 20130101; C08G 75/23 20130101; C08G 2261/3444 20130101;
C08G 8/02 20130101; C08G 65/4012 20130101; C07C 315/06 20130101;
C08G 65/4093 20130101; C01D 7/00 20130101 |
Class at
Publication: |
528/126 ;
528/125 |
International
Class: |
C08G 8/02 20060101
C08G008/02 |
Claims
1. A process for preparing a semi-crystalline poly(aryl ether
ketone), said process comprising reacting a nucleophile with a
4,4'-difluorobenzophenone, wherein the 4,4'-difluorobenzophenone
meets the following impurity limitation:
[2,4'-difluorobenzophenone]+[4-monofluorobenzophenone].ltoreq.1250
ppm wherein the amounts of 2,4'-difluorobenzophenone and
4-monofluorobenzophenone in 4,4'-difluorobenzophenone are
determined by liquid chromatography analysis.
2. The process according to claim 1, wherein the
4,4'-difluorobenzophenone further meets the following impurity
limitation: [2,4'-difluorobenzophenone].ltoreq.750 ppm.
3. The process according to claim 1, wherein the
4,4'-difluorobenzophenone further meets the following impurity
limitations: [2,4'-difluorobenzophenone].ltoreq.750 ppm, and
[4-monofluorobenzophenone].ltoreq.500 ppm.
4. The process according to claim 1, wherein the
4,4'-difluorobenzophenone further meets the following impurity
limitations: [2,4'-difluorobenzophenone].ltoreq.300 ppm, and
[4-monofluorobenzophenone].ltoreq.950 ppm.
5. The process according to claim 1, wherein the
4,4'-difluorobenzophenone further meets the following impurity
limitations: [total chlorine content].ltoreq.0.075 wt. % wherein
the total chlorine content is determined by a combustion followed
by microcoulometric titration analysis (TOX).
6. The process according to claim 1, wherein the
4,4'-difluorobenzophenone further meets the following impurity
limitations: [chlorofluorobenzophenone].ltoreq.5000 ppm.
7. The process according to claim 1, wherein the
4,4'-difluorobenzophenone has a GC purity of .ltoreq.99.9 area
%.
8. The process according to claim 7, wherein the
4,4'-difluorobenzophenone has a GC purity of .ltoreq.99.9 area
%.
9. The process according to claim 1, wherein the nucleophile is
selected from the group consisting of p-hydroquinone,
4,4'-dihydroxybenzophenone, 4,4'-biphenol,
1,4-bis-(p-hydroxybenzoyl)benzene, and
1,3-bis-(p-hydroxybenzoyl)benzene.
10. The process according to claim 1, wherein the poly(aryl ether
ketone) is poly(ether ether ketone) (PEEK).
11. The process according to claim 10, wherein the poly(aryl ether
ketone) has a heat of fusion in J/g.gtoreq.68.0-26.6*RV (dl/g)
where RV is the polymer reduced viscosity measured at 25.degree. C.
in concentrated H.sub.2SO.sub.4.
12. The poly(aryl ether ketone) according to claim 1, wherein the
poly(aryl ether ketone) is poly(ether ketone) (PEK).
13. The process according to claim 1, wherein the reaction is
carried out in the presence of diphenylsulfone.
14. The process according to claim 1, wherein the nucleophile is
reacted with the 4,4'-difluorobenzophenone via aromatic
nucleophilic substitution in the presence of particulate sodium
carbonate, said particulate sodium carbonate having a particle size
distribution as follows: D.sub.90.gtoreq.45 .mu.m, and
D.sub.90.ltoreq.250 .mu.m, and D.sub.99.5.ltoreq.710 .mu.m.
15. A poly(aryl ether ketone) obtainable by or prepared according
to the process of claim 1.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the priority benefit to U.S.
provisional application No. 61/108,096 filed on Oct. 24, 2008, to
U.S. provisional application No. 61/108,097 filed on Oct. 24, 2008,
and to U.S. provisional application No. 61/140,205 filed on Dec.
23, 2008, the whole content of all these applications being herein
incorporated by reference for all purposes.
FIELD OF THE INVENTION
[0002] The present invention relates to highly pure
4,4'-difluorobenzophenone (4,4'-DFBP). Also described is the use of
this highly pure 4,4'-DFBP in the preparation of poly(aryl ether
ketone) polymers (PAEK), and the resulting PAEK polymers.
BACKGROUND OF THE INVENTION
[0003] 4,4'-difluorobenzophenone (4,4'-DFBP) is a well known
chemical intermediate having the following chemical formula:
##STR00001##
[0004] 4,4'-DFBP is known to be useful in the preparation of, e.g.,
PAEK polymers such as PEEK and PEK. PAEK polymers are a well known
class of engineering polymers useful in various fields of
endeavour. Processes for preparing PAEK polymers, including those
using 4,4'-DFBP, can be found in, e.g., U.S. Pat. Nos. 3,953,400,
3,956,240, 3,928,295, and 4,176,222, all incorporated herein by
reference. Generally, PAEK polymers are prepared by aromatic
nucleophilic substitution. For example, p-hydroquinone, commonly
referred to as "hydroquinone", a bisphenol, etc. can be used as a
nucleophilic component which is deprotonated with a base such as
NaOH, Na.sub.2CO.sub.3 or K.sub.2CO.sub.3 to form a nucleophile
that then reacts with, e.g., a dihalobenzophenone such as 4,4'-DFBP
to form a PAEK polymer via nucleophilic substitution, with the
fluorine atoms of the 4,4'-DFBP acting as leaving groups.
[0005] It is generally known that purified starting materials are
preferred in the chemical synthesis of complex molecules, and this
is true for monomers used in the synthesis of PAEK polymers. For
example, WO2007/144610 and WO2007/144615 describe the use of
monomers having a purity of at least 99.7 area %, including 99.9
area % (as measured by gas chromatography), as providing improved
melt flow index in the product polymer. It should be noted that a
material that is 99.9% pure contains 1000 ppm of one or more
impurities. However, these references remain silent on the nature
and amount of specific impurities to be avoided. In addition, this
measurement by area % leads only to a general purity level of the
monomers and is nonspecific with regard to the type and amount of
specific impurities to be avoided.
[0006] Common impurities of 4,4'-difluorobenzophenone are for
example other positional isomers (mainly the 3, 4' and 2, 4'
isomers), coloured impurities and polymeric by-products as
described in U.S. Pat. No. 5,777,172.
[0007] Semi-crystalline poly(aryl ether ketone)s exhibit
interesting properties as compared to their amorphous counterparts
including, notably, excellent chemical resistance and good
mechanical properties over a large temperature range. Ultimate
mechanical properties of semi-crystalline resins are in particular
linked to the crystallinity level. A high level of crystallinity is
thus important to maintain these properties. Another important
property of PAEK polymers is their melt stability.
[0008] There is a long felt need for PAEK polymer having improved
chemical resistance and mechanical properties over a large
temperature range, and therefore PAEK polymer with improved
crystallinity and/or melt stability are needed.
SUMMARY OF THE INVENTION
[0009] The art, while generally recognizing that the purity of
4,4'-DFBP can have an influence on PAEK polymers obtained
therewith, does not identify which impurities in 4,4'-DFBP should
be limited, and to what extent. This is in particular true for
semi-crystalline PAEK polymers, which have different monomer purity
requirements from amorphous PAEK. Only semi-crystalline PAEK have
gained wide acceptance due to their increased chemical resistance
properties. A semi-crystalline polymer is a polymer which
crystallizes on cooling from the melt or from solution. The amount
of crystallinity can be determined by different methods
("Crystallinity Determination", J. Runt, M. Kanchanasopa,
"Encyclopaedia Of Polymer Science and Technology", Online Ed,
2004), Wide Angle X-Ray diffraction (WAXD) or Differential Scanning
calorimetry (DSC) are two common methods used to determine
crystallinity. By DSC, the reference (Blundell et al., Polymer,
1983, V 24, P 953) is that a fully crystalline PEEK exhibits an
enthalpy of fusion of 130 J/g. Semi-crystalline PAEK have
crystallinity levels of above 5%, preferably above 10% as measured
by WAXD or by DSC.
[0010] As will be explained in detail below, the present inventor
has now discovered that when the amounts of specific impurities in
4,4'-DFBP, namely 2,4'-difluorobenzophenone, 4-mono
fluorobenzophenone and chlorinated organics, are controlled as
described herein a PAEK polymer is obtained having improved
crystallinity and/or melt stability. The inventor has also
discovered that the presence of chlorine end groups has a
deleterious effect on the stability of the whole polymer.
[0011] The method described in WO2007/144610 and WO2007/144615 does
not allow baseline separation of the 2,4'-difluorobenzophenone and
4-monofluorobenzophenone impurities found in 4,4'-DFBP: hence a
quantitative determination of these key impurities is ambiguous
using this method. In fact, the quite similar structures and
boiling points of the different difluorobenzophenone isomers lead
to complicated chromatograms where the isomers cannot be clearly
and unambiguously separated from each other (overlapping or
shouldering), when using common high pressure liquid chromatography
(HPLC) or gas chromatography (GC) methods.
[0012] The inventor of the present invention has found out that the
gas chromatography method described in WO2007/144610 and
WO2007/144615 is not suitable for the purity determination of DFBP,
since it does not allow the differentiation of specific impurities.
The inventor has found out that the liquid chromatography analysis
of DFBP is much more appropriate and allows the detection of
specific impurities which presence has an adverse effect on the
PAEK properties.
BRIEF DESCRIPTION OF THE DRAWING
[0013] For a detailed description of the invention, reference will
now be made to the accompanying drawing in which:
[0014] FIG. 1 represents a graph of the enthalpy of fusion of
polymers according to the present invention versus the reduced
viscosity (RV) of the polymers.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] PAEK are generally prepared by aromatic nucleophilic
substitution, i.e. a fundamental class of substitution reaction in
which an "electron rich" nucleophile selectively bonds with or
attacks the positive or partially positive charge of an atom
attached to a group or atom called the leaving group; the positive
or partially positive atom is referred to as an electrophile. A
nucleophile is thus intended to denote a reagent that forms a
chemical bond to its reaction partner (the electrophile) by
donating both bonding electrons. Common nucleophilic monomers used
in the synthesis of PAEK are hydroxylated monomers such as
p-hydroquinone (commonly known as "hydroquinone"),
4,4'-dihydroxybenzophenone, 4,4'-biphenol,
1,4-bis-(p-hydroxybenzoyl)benzene,
1,3-bis-(p-hydroxybenzoyl)benzene, etc. On the other hand, common
electrophilic monomers used in the synthesis of PAEK are
4,4'-difluorobenzophenone, 1,4-bis(p-fluorobenzoyl)benzene;
1,3-bis(p-fluorobenzoyl)benzene, 4,4'-bis(p-fluorobenzoyl)biphenyl,
etc. 4,4'-DFBP is frequently used as an electrophile in the
preparation of PAEK polymers such as PEEK and PEK. In studying
4,4'-DFBP impurities the inventor has found that
2,4'-difluorobenzophenone (2,4'-DFBP), 4-monofluorobenzophenone
(4-FBP), and monochloromonofluorobenzophenone
(chlorofluorobenzophenone, C1FBP) to be commonly present in
commercially available 4,4'-DFBP. In addition, the inventor has
discovered that both 2,4'-DFBP and 4-FBP have a deleterious effect
on PAEK crystallinity as measured by the heat of fusion on the
2.sup.nd heat cycle in DSC and that chlorofluorobenzophenone has a
deleterious effect on PAEK resin melt stability.
[0016] The inventor, after much study, has further discovered that
in order to maintain acceptable crystallinity the levels of
2,4'-DFBP and 4-FBP in 4,4'-DFBP should obey a particular
relationship with regard to their amount present.
[0017] A first aspect of the present invention is thus related to a
process for preparing a PAEK by reacting a nucleophile with
4,4'-difluorobenzophenone (4,4'-DFBP), the improvement comprising
using a 4,4'-DFBP that meets at least one, and preferably both, of
the following impurity limitations:
[2,4'-difluorobenzophenone].ltoreq.750 ppm,
[2,4'-difluorobenzophenone]+[4-monofluorobenzophenone].ltoreq.1250
ppm wherein the amounts of 2,4'-difluorobenzophenone and
4-monofluorobenzophenone in 4,4'-difluorobenzophenone are
determined by liquid chromatography analysis, as described in the
following examples; where these expressions mean that: [0018] the
content of 2,4'-DFBP in the 4,4'-DFBP is less than or equal to 750
ppm and [0019] the content of 2,4'-DFBP in the 4,4'-DFBP plus the
content of 4-FBP in the 4,4'-DFBP is in total less than or equal to
1250 ppm.
[0020] In the description, impurities levels are expressed on
weight basis, i.e. weight of the impurity of concern/(weight of the
4,4'-DFBP+weight of all present impurities), expressed either in
parts per million or in wt. %.
[0021] Generally chromatographic data is presented as a graph of
detector response (y-axis) against retention time (x-axis). This
provides a spectrum of peaks for a sample representing the analytes
present in a sample eluting from the column at different times.
Retention time can be used to identify analytes if the method
conditions are constant. Also, the pattern of peaks will be
constant for a sample under constant conditions and can identify
complex mixtures of analytes. In most modern applications however
the GC or LC apparatus is connected to a mass spectrometer or
similar detector that is capable of identifying the analytes
represented by the peaks. The area under a peak is proportional to
the amount of analyte present. By calculating the area of the peak
using the mathematical function of integration, the concentration
of an analyte in the original sample can be determined. In most
modern systems, computer software is used to draw and integrate
peaks.
[0022] In the process according to the present invention the
4,4'-DFBP contains at most 750 ppm of
2,4'-difluorobenzophenone.
[0023] Preferably, the 4,4'-DFBP meets the following impurity
limitations: [2,4'-difluorobenzophenone].ltoreq.750 ppm, more
preferably 300 ppm, and [4-mono fluorobenzophenone].ltoreq.950 ppm,
more preferably 500 ppm.
[0024] In a preferred embodiment the 4,4'-DFBP meets the following
impurity limitations: [2,4'-difluorobenzophenone].ltoreq.750 ppm,
and [4-mono fluorobenzophenone].ltoreq.500 ppm.
[0025] In another preferred embodiment the 4,4'-DFBP meets the
following impurity limitations:
[2,4'-difluorobenzophenone].ltoreq.300 ppm, and [4-mono
fluorobenzophenone].ltoreq.950 ppm.
[0026] In another preferred embodiment [2,4'-DFBP].ltoreq.750 ppm
(including .ltoreq.700, 650, 600, 550, 500, 450, 400, 350, 300,
250, 200, 150, 100, 50 ppm etc., of course including 0 ppm, and all
values and subranges between stated values as if explicitly written
out) and [4-FBP].ltoreq.500 ppm (including .ltoreq.450, 400, 350,
300, 250, 200, 150, 100, 50 ppm etc., of course including 0 ppm,
and all values and subranges between stated values as if written
out).
[0027] In another preferred embodiment [2,4'-DFBP].ltoreq.300 ppm
(including .ltoreq.250, 200, 150, 100, 50 ppm etc., of course
including 0 ppm, and all values and subranges between stated values
as if explicitly written out) and [4-FBP].ltoreq.950 ppm (including
.ltoreq.900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350,
300, 250, 200, 150, 100, 50 ppm etc., of course including 0 ppm,
and all values and subranges between stated values as if explicitly
written out).
[0028] In another preferred embodiment
[2,4'-difluorobenzophenone]+[4-monofluorobenzophenone].ltoreq.1250
ppm (including .ltoreq.1200, 1100, 1000, 900, 800, 700, 600, 500,
400, 300, 200, 100, 50 ppm etc., of course including 0 ppm, and all
values and subranges between stated values as if explicitly written
out).
[0029] In another preferred embodiment the total chlorine content
(representing the chlorinated organics) in the 4,4'-DFBP should be
0.075 wt. % or less, preferably 0.053 wt % or less (including 0.05,
0.045, 0.040, 0.035, 0.030, 0.025, 0.020 wt % or less etc., of
course including 0 wt %, and all values and subranges between
stated values as if written out) which, expressed as
chlorofluorobenzophenone, is .ltoreq.5000, ppm, 3500 ppm or less
(including .ltoreq.3400, 3300, 3200, 3100, 3000, 2750, 2500, 2250,
2000, 1750, 1500, 1250, 1000, 900, 850, 800, 750, 700, 650, 600,
550, 500, 450, 400, 350, 300, 250, 200, 150, 100, 50 ppm etc., of
course including 0 ppm, and all values and subranges between stated
values as if explicitly written out. Chlorofluorobenzophenone
contains 15% of the chlorine element; so 0.053% chlorine=530 ppm
Cl=(530/0.15) ppm chlorofluorobenzophenone=3530 ppm.
[0030] This total chlorine content (representing the chlorinated
organics) in the 4,4'-DFBP is determined by Total Organic Halogen
analysis (TOX), i.e. by combustion followed by microcoulometric
titration analysis (TOX), as described in the following
examples.
[0031] In a particular embodiment, the 4,4'-difluorobenzophenone
used in the process according to the present invention may have a
GC purity of .ltoreq.99.9 area %, and even .ltoreq.99.9 area %,
since some impurities have no adverse effect on the PAEK
properties.
[0032] Another aspect of the present invention is related to a
4,4'-DFBP that meets all the above described impurity limitations,
and in particular: [2,4'-difluorobenzophenone].ltoreq.750 ppm and
[2,4'-difluorobenzophenone]+[4-monofluorobenzophenone].ltoreq.1250
ppm.
[0033] Preferably, the 4,4'-DFBP according to the present invention
meets the following impurity limitations:
[2,4'-difluorobenzophenone].ltoreq.750 ppm, more preferably 300 ppm
and [4-monofluorobenzophenone].ltoreq.950 ppm, more preferably 500
ppm.
[0034] In another preferred embodiment, the 4,4'-DFBP according to
the present invention meets at least two, preferably at least three
and more preferably all the above mentioned impurity
limitations.
[0035] Still another aspect of the present invention is related to
PAEK polymer obtainable by or prepared according to the process as
above described.
[0036] Improved melt stability and/or improved crystallinity may be
observed under these conditions. Ultimate mechanical properties of
semi-crystalline resins are linked to the crystallinity level. The
enthalpy of fusion as measured by DSC provides an easy measure of
the polymer crystallinity level. Acceptable crystallinity depends
on the polymer (PEEK is different from PEK) and on the polymer
molecular weight as measured by its reduced viscosity (RV). The
inventor has found out that acceptable ranges, i.e. those leading
to good mechanical properties, for PEEK and PEK are as follows. For
PEEK, the acceptable enthalpy of fusion, also described as the
target enthalpy of fusion, is .gtoreq.68.0-26.6*RV, (more
preferably .gtoreq.69.0-26.6*RV) wherein RV is the reduced
viscosity measured in H.sub.2SO.sub.4. For PEK it is
.gtoreq.72.0-21.0*RV; more preferably .gtoreq.74.0-21.0*RV.
[0037] Another aspect of the present invention is thus related to a
poly(aryl ether ketone), wherein the poly(aryl ether ketone) is
PEEK having a heat of fusion in J/g.gtoreq.68.0-26.6*RV (dl/g)
where RV is the polymer reduced viscosity measured at 25.degree. C.
in concentrated H.sub.2SO.sub.4, or wherein the poly(aryl ether
ketone) is PEK.
[0038] Melt stability can be measured by the ratio of melt flow
index measured at different holding times. Details of the methods
are described further. Melt flow ratio (MFR) is preferably between
0.5 and 1.5, preferably between 0.5 and 1.2.
[0039] Amounts of all these impurities (2,4'-DFBP, 4-FBP, total
chlorine content, chlorofluorobenzophenone) can be measured in the
4,4'-DFBP using the test methods described in examples. Enthalpy of
fusion can be determined by DSC as described in the examples. All
of these measurement techniques are within the skill of the
ordinary artisan.
[0040] It is within the skill of the ordinary artisan to purify
4,4'-DFBP in order to meet, both singly and collectively, the above
impurity limits for all of 2,4'-DFBP, 4-FBP, total chlorine
content, and chlorofluorobenzophenone using, for example,
techniques such as chromatography, washing with a non solvent,
dissolution in a solvent at high temperature and recrystallization
at low temperature, distillation optionally under vacuum, ion
exchange, etc.
[0041] 4,4'-DFBP meeting one or more of the purity descriptions
herein is particularly useful in the preparation of poly(aryl ether
ketone) (PAEK) polymers.
[0042] The term "poly(aryl ether ketone)" (PAEK) as used herein
includes any polymer of which more than 50 wt. % of the recurring
units are recurring units (R1) of one or more formulae containing
at least one arylene group, at least one ether group (--O--) and at
least one ketone group [--C(.dbd.O)--] and which was prepared using
4,4'-DFBP as a starting material.
[0043] Preferably, recurring units (R1) are chosen from:
##STR00002##
wherein: Ar is independently a divalent aromatic radical selected
from phenylene, biphenylene or naphthylene, X is independently O,
C(.dbd.O) or a direct bond, n is an integer of from 0 to 3, b, c, d
and e are 0 or 1, a is an integer of 1 to 4, and preferably, d is 0
when b is 1.
[0044] More preferably, recurring units (R1) are chosen from:
##STR00003##
[0045] Still more preferably, recurring (R1) are chosen from:
##STR00004##
[0046] Most preferably, recurring units (R1) are:
##STR00005##
[0047] A PEEK polymer is intended to denote any polymer of which
more than 50 wt. % of the recurring units are recurring units (R1)
of formula (VII). A PEK polymer is intended to denote any polymer
of which more than 50 wt. % of the recurring units are recurring
units (R1) of formula (VI).
[0048] The poly(aryl ether ketone) may be notably a homopolymer, a
random, alternate or block copolymer. When the poly(aryl ether
ketone) is a copolymer, it may notably contain (i) recurring units
(R1) of at least two different formulae chosen from formulae (VI)
to (XV), or (ii) recurring units (R1) of one or more formulae (XVI)
to (XXV) and recurring units (R1*) different from recurring units
(R1):
##STR00006##
[0049] Preferably more than 70 wt. %, more preferably more than 85
wt. % of the recurring units of the poly(aryl ether ketone) are
recurring units (R1). Still more preferably, essentially all the
recurring units of the poly(aryl ether ketone) are recurring units
(R1). Most preferably, all the recurring units of the poly(aryl
ether ketone) are recurring units (R1).
[0050] The PAEK according to the present invention is a
semi-crystalline PAEK, preferably a semi-crystalline PEEK. A
semi-crystalline PAEK is intended to denote a PAEK featuring areas
of crystalline molecular structure, but also having amorphous
regions. In contrast with completely amorphous PAEKs,
semi-crystalline PAEKs have generally a melting point. Very often,
the existence of a melting point is detected and the value of the
melting point is measured by Differential Scanning calorimetry, for
example as reported in the examples. The melting point is
advantageously determined by a certain construction procedure on
the heat flow curve: the intersection of the two lines that are
tangent to the peak at the points of inflection on either side of
the peak define the peak temperature, namely the melting point. In
accordance with the present invention, the semi-crystalline PAEK
has a melting point advantageously greater than 150.degree. C.,
preferably greater than 250.degree. C., more preferably greater
than 300.degree. C. and still more preferably greater than
325.degree. C.
[0051] A particularly preferred PAEK polymer prepared using the
invention 4,4'-DFBP is a homopolymer of recurring units (R1) of
formula (VII), i.e. a polymer of which all the recurring units of
the poly(aryl ether ketone) are recurring units (R1) of formula
(VII).
[0052] This PEEK homopolymer preferably has a RV of between 0.50
and 1.40; more preferably between 0.60 and 1.30 and can be made
using, e.g., the invention 4,4'-DFBP and p-hydroquinone. Using the
DSC conditions detailed in the examples, the target heat of fusion
in J/g for this PEEK polymer is preferably .gtoreq.68.0-26.6*RV
(dl/g) where RV is the polymer reduced viscosity measured at
25.degree. C. in concentrated H.sub.2SO.sub.4, as detailed in the
examples.
[0053] U.S. Pat. Nos. 3,953,400, 3,956,240, 3,928,295, and
4,176,222, and RE 34085, all incorporated herein by reference, also
disclose PAEK resins and methods for their preparation. As noted
above, PAEK polymers are generally prepared by aromatic
nucleophilic substitution. For example, a bisphenol can be
deprotonated with a base such as NaOH, Na.sub.2CO.sub.3 or
K.sub.2CO.sub.3 and the resultant bisphenolate may then react with,
e.g., a dihalobenzophenone, especially 4,4'-DFBP, via nucleophilic
substitution with the halogen atoms of the dihalobenzophenone,
especially the fluorine atoms of the 4,4'-difluorobenzophenone
(4,4'-DFBP), acting as leaving groups.
[0054] Such PAEK reactions are typically carried out in a solvent,
that often is, or that often contains, diphenylsulfone. However,
other solvents can be used: benzophenone, dibenzothiophene dioxide,
etc.
[0055] In the process according to the present invention, a
semi-crystalline PAEK is prepared by reacting a nucleophile with a
4,4'-DFBP meeting the specific one or more impurity limitation(s)
as previously detailed.
[0056] In the process according to the present invention, various
nucleophiles may be used. The nucleophile used in the present
invention is preferably selected from the group consisting of
p-hydroquinone (commonly known as "hydroquinone"),
4,4'-dihydroxybenzophenone, 4,4'-biphenol,
1,4-bis-(p-hydroxybenzoyl)benzene,
1,3-bis-(p-hydroxybenzoyl)benzene and mixtures thereof. More
preferably, it is p-hydroquinone. In the process according to the
present invention, the reacting of the nucleophile with the
4,4'-difluorobenzophenone takes advantageously place via aromatic
nucleophilic substitution in a solvent. The solvent includes
preferably diphenylsulfone meeting one or more impurity
limitations, as specified in embodiment (D) hereinafter.
Embodiment (D)
[0057] In a preferred embodiment (D) of the present invention, the
process for preparing a semi-crystalline poly(aryl ether ketone) is
a process by reacting a nucleophile with a
4,4'-difluorobenzophenone via aromatic nucleophilic substitution in
a solvent comprising a diphenylsulfone, wherein said
diphenylsulfone meets at least one of the following impurity
limitations:
TABLE-US-00001 Monomethyldiphenylsulfone content (sum of all Less
than 0.2 area % isomers) Monochlorodiphenylsulfone content (sum of
all Less than 0.08 area % isomers) Sodium content Less than 55 ppm
Potassium content Less than 15 ppm Iron content Less than 5 ppm
Residual acidity content Less than 2.0 .mu.eq/g Diphenylsulfide
content Less than 2.0 wt. % APHA of 20 wt. % solution in acetone at
25.degree. C. Less than 50 Total chlorine content Less than 120
ppm
where ppm and wt. % are based on the total weight of the
diphenylsulfone and area % represents the ratio of the GC peak area
of the impurity of concern over the total area of all GC peaks of
the diphenylsulfone.
[0058] The residual acidity content in diphenylsulfone can be
determined as follows. Approximately 3 g of diphenylsulfone sample
is weighed to the nearest 0.1 mg and added to an empty glass
titration vessel. 55 ml of high-purity methylene chloride is added,
followed by addition of a 5.00 ml aliquot of spiking solution,
which contains six drops of 37% hydrochloric acid per liter, into
the same titration vessel. The vessel is then attached to the
titrator cell assembly containing the buret tip, pH electrode, and
magnetic stirrer. The vessel is then purged with carbon dioxide
free nitrogen for 5-7 minutes. While continuing the nitrogen purge,
the vessel contents is titrated with 0.025 N tetrabutylammonium
hydroxide in 1:12 methanol:toluene and the volume of titrant
required to reach the strong acid endpoint is measured. A blank
titration is performed using the same parameters, except that the
sample was omitted. Results are calculated using the following
equation:
Acidity=((VS1 VB1)*N*100000)/W in microequivalents per gram of
sample
[0059] Where VS1 is the amount of titrant in ml required to reach
the strong acid/base equivalence points when sample solution is
titrated and VB1 is the amount of titrant in ml required to reach
the strong acid/base equivalence point when only the blank solution
is titrated, W is the sample weight, and N is the normality of the
tetrabutylammonium hydroxide titrant. If acidity is negative, the
sample contains basic species.
[0060] The sodium, potassium, and iron content in diphenylsulfone
can be determined as follows. Concentrations of sodium, potassium,
and iron are measured in diphenylsulfone by ashing of the sample
followed by measurement of element concentration by
inductively-coupled plasma atomic emission spectrometry.
Approximately 3 g of diphenylsulfone sample is weighed into
platinum crucibles using an analytical balance. Two drops of
concentrated, trace metals grade sulfuric acid is added to each
sample and the crucibles are placed into a muffle furnace set to
250.degree. C. After the diphenylsulfone has vaporized, the furnace
temperature is raised to 525.degree. C. for 1 hour to remove any
organic residues. Metallic residues are dissolved by adding 1 ml of
concentrated hydrochloric acid to the crucible and warming at
50.degree. C. to dissolve the ash. After addition of 5 ml of
deionized water and additional warming, crucible contents are
quantitatively transferred to a 25-ml volumetric flask, diluted to
the mark with deionized water, and mixed well. The diluted
solutions are then analyzed by ICP-AES against standards made from
certified sodium, potassium, and iron standard solutions. Emission
is monitored at the following wavelengths for the elements of
interest: sodium: 589.592 nm, potassium: 766.490 nm and iron:
238.204 nm. Plasma conditions used for the analysis are: plasma
input power: 1300 watts, plasma argon flow: 15 liters per minute,
auxiliary argon flow: 0.5 liters per minute, nebulizer flow: 1.2
liters per minute, and sample flow rate: 1.5 milliliters per
minute. Element concentrations in the samples are calculated by the
ICP operating software from the element emission line
intensities.
[0061] The total chlorine content in diphenylsulfone can be
determined as follows. Using forceps, a clean, dry combustion boat
is placed onto a microbalance, and the balance is zeroed. 1 mg of
diphenylsulfone sample is weighed into the boat and weight is
recorded to 0.001 mg. The combustion boat and sample are placed in
the introduction port of a Thermo Electron Corporation ECS 1200
Halogen Analyzer, and the port is capped. The sample weight is
entered into the sample weight field on the instrument computer.
The sample analysis cycle is then started. The sample is burned in
a mixture of argon and oxygen and the combustion products are
carried by the combustion gas stream into a titration cell.
Hydrogen chloride produced from the combustion is absorbed into the
cell solution from the gas stream, and is coulometrically titrated
with silver ions. Total chlorine content is displayed at the end of
the titration.
[0062] The diphenylsulfide content in diphenylsulfone can be
determined by liquid chromatography, as explained hereinafter. HPLC
analysis is carried out on a Waters Alliance 2795 LC instrument
using a Supelco Discovery HS F5 25 cm.times.4.6 mm column. The
analysis conditions are:
[0063] Mobile phase: acetonitrile/deionized water.
[0064] Gradient: 60/40 acetonitrile/water, hold for 5 minutes,
increase to 100% acetonitrile in further 10 minutes, hold for 5
minutes at 100% acetonitrile
[0065] Flow rate: 1 ml/minute
[0066] Injection volume: 10 .mu.l
[0067] Detection: UV at 254 nm
[0068] The sample is prepared by dissolving 0.2 g of DPS in 10 g of
acetonitrile. The concentration of diphenylsulfide is determined
using a low concentration diphenylsulfide as an external
calibration standard (commercially available). The retention time
for DPS is typically 6.2 minutes and the retention time for
diphenylsulfide is typically 10.7 minutes. The diphenylsulfide
concentration in the DPS sample is assessed by the area of the
diphenylsulfide peak/total peak area of DPS plus impurities.
[0069] The monochlorodiphenylsulfone and monomethyldiphenylsulfone
content in diphenylsulfone can be determined by gas chromatography,
as explained hereinafter. GC analysis is performed on an HP5890
series 11 gas chromatograph using a Restek RTx-5MS, 15 m.times.0.25
mm internal diameter.times.0.25 .mu.m film thickness column. The
following GC conditions are used:
[0070] Helium flow rate: 1 ml/minute,
[0071] Injector temperature: 250.degree. C.
[0072] FID temperature: 250.degree. C.
[0073] Oven Temperature Program: 100.degree. C., hold 1 minute,
30.degree. C./minute to 250.degree. C., hold 1 minute
[0074] Total run time: 14 minutes
[0075] Injection volume: 1 .mu.l
[0076] Split 40:1
[0077] The sample is prepared by dissolving 0.2 g of DPS in 5 ml of
acetone. The GC retention times for monomethyldiphenylsulfone
isomers are typically 8.0 and 8.1 minutes and for
monochlorodiphenylsulfone 8.2 minutes. The identity of the
impurities is determined by GCMS run on the sample solution. The
impurity concentrations are quoted as area %, calculated from GC
FID peak areas. When several isomers are present, the concentration
includes the sum of these isomers.
[0078] The color (APHA) of DPS in acetone can be determined as
follows. 20 g of diphenylsulfone are dissolved in 80 g of acetone
at 25.degree. C. The acetone used contains less than 0.5 wt. %
water. Color of the solution is measured as compared to Pt-Co
standards in the APHA scale (ASTM D1209-00), using a Gretag Macbeth
Color Eye Ci5 Spectrophotometer for the comparison. The blank used
is distilled water.
[0079] In the process in accordance with embodiment (D) of the
present invention, said diphenylsulfone meets preferably the
impurity limitations for monomethyldiphenylsulfone,
monochlorodiphenylsulfone, and residual acidity.
[0080] Additionally or alternatively, in the process in accordance
with embodiment (D) of the present invention, said diphenylsulfone
meets preferably the impurity limitations for sodium, iron,
diphenylsulfide, and APHA of 20 wt. % solution in acetone at
25.degree. C.
[0081] In the process in accordance with embodiment (D) of the
present invention, excellent results were obtained when all the
impurity limitations as above recited were met.
[0082] In the process according to the present invention, the
reacting of the nucleophile with the 4,4'-difluorobenzophenone
takes advantageously place via aromatic nucleophilic substitution
in the presence of alkali-metal carbonate, often under an inert
atmosphere and often at temperatures approaching the melting point
of the polymer. The alkali-metal carbonate includes preferably
particulate sodium carbonate having a certain particle size
distribution, as specified in embodiment (E) hereinafter.
Embodiment (E)
[0083] In a preferred embodiment (E) of the present invention, the
process for preparing a semi-crystalline poly(aryl ether ketone) is
a process by reacting a nucleophile with a
4,4'-difluorobenzophenone via aromatic nucleophilic substitution in
the presence of particulate sodium carbonate, wherein the
4,4'-difluorobenzophenone meets the one or more impurity
limitation(s) as above detailed, and said particulate sodium
carbonate has a particle size distribution as follows:
[0084] D.sub.90.gtoreq.45 .mu.m and D.sub.90.ltoreq.250 .mu.m and
D.sub.99.5.ltoreq.710 .mu.m.
[0085] As used herein, a sodium carbonate particle size
distribution expressed as D.sub.xx.ltoreq.Y .mu.m refers to the
percentage (xx %) of sodium carbonate particles by weight in a
sample that are less than or equal to Y .mu.m in diameter.
[0086] On one hand, in accordance with embodiment (E),
Na.sub.2CO.sub.3 that is "too fine" is avoided as it can notably
lead to a low bulk density product that is difficult to handle and
synthesis reaction kinetics that are difficult to control. With
this regard, the Applicant found that Na.sub.2CO.sub.3 with a
D.sub.90.gtoreq.45 .mu.m was beneficial.
[0087] On the other hand, in accordance with embodiment (E),
Na.sub.2CO.sub.3 that contains a certain amount of "big" particles,
and especially of "very big" particles (i.e., typically of about
710 .mu.m or more), is also to be avoided as it can notably slow
down the polymerization rate, or require the use of an undesirably
high amount of K.sub.2CO.sub.3 or other higher alkali metal
carbonate (at fixed Na.sub.2CO.sub.3 amount); Na.sub.2CO.sub.3 that
contains a certain amount of "big" particles, and especially of
"very big" particles, can also result in polymerizations having
poor kinetics consistency. With this regard, the Applicant found
that Na.sub.2CO.sub.3 with a D.sub.90.ltoreq.250 .mu.m and with a
D.sub.99.5.ltoreq.710 .mu.m was also beneficial.
[0088] The use of particulate sodium carbonate in accordance with
embodiment (E) provides several benefits, including the ability to
synthesize easily PAEKs in the absence of a cosolvent forming an
azeotrope with water such as p-xylene, and thereby prepare PAEKs
with no trace of residual cosolvent (such cosolvents, like
p-xylene, are generally toxic). Cosolvents forming an azeotrope
with water used in the synthesis of PAEK resins are known to those
of skill in the art, and in addition to p-xylene include
chlorobenzene, toluene, etc. The use of particulate sodium
carbonate in accordance with embodiment (E) makes it also possible
to manufacture lower color, whiter PAEK resins. The use of
particulate sodium carbonate in accordance with embodiment (E)
results also beneficially in improved kinetics consistency.
[0089] Preferably, the D.sub.99.5 of the sodium carbonate particles
in accordance with embodiment (E) is of at most 630 .mu.m; more
preferably, it is of at most 500 .mu.m; still more preferably, it
is of at most 425 .mu.m; most preferably, it is of at most 355
.mu.m.
[0090] Preferably, the D.sub.90 of the sodium carbonate particles
in accordance with embodiment (E) is of at least 63 .mu.m; more
preferably, it is of at least 90 .mu.m; still more preferably, it
is of at least 112 .mu.m.
[0091] Preferably, the D.sub.90 of the sodium carbonate particles
in accordance with embodiment (E) is of at most 212 .mu.m; more
preferably, it is of at most 180 .mu.m; still more preferably, it
is of at most 150 .mu.m.
[0092] In certain preferred sub-embodiments of embodiment (E), the
sodium carbonate has the following particle size distributions:
[0093] D.sub.99.5.ltoreq.630 .mu.m, D.sub.90.ltoreq.212 .mu.m, and
D.sub.90.gtoreq.45 .mu.m; or
[0094] D.sub.99.5.ltoreq.500 D.sub.90.ltoreq.212 .mu.m, and
D.sub.90.gtoreq.45 .mu.m; or
[0095] D.sub.99.5.ltoreq.425 .mu.m, D.sub.90.ltoreq.212 .mu.m, and
D.sub.90.gtoreq.45 .mu.m; or
[0096] D.sub.99.5.ltoreq.630 .mu.m, D.sub.90.ltoreq.180 .mu.m, and
D.sub.90.gtoreq.45 .mu.m; or
[0097] D.sub.99.5.ltoreq.500 .mu.m, D.sub.90.ltoreq.180 .mu.m, and
D.sub.90.gtoreq.45 .mu.m; or
[0098] D.sub.99.5.ltoreq.425 .mu.m, D.sub.90.ltoreq.180 .mu.m, and
D.sub.90.gtoreq.45 .mu.m; or
[0099] D.sub.99.5.ltoreq.630 .mu.M, D.sub.90.ltoreq.212 .mu.m, and
D.sub.90.gtoreq.63 .mu.m; or
[0100] D.sub.99.5.ltoreq.500 .mu.m, D.sub.90.ltoreq.212 .mu.m, and
D.sub.90.gtoreq.63 .mu.m; or
[0101] D.sub.99.5.ltoreq.425 .mu.m, D.sub.90.ltoreq.212 .mu.m, and
D.sub.90.gtoreq.63 .mu.m; or
[0102] D.sub.99.5.ltoreq.630 .mu.m, D.sub.90.ltoreq.212 .mu.m, and
D.sub.90.gtoreq.90 .mu.m; or
[0103] D.sub.99.5.ltoreq.500 .mu.m, D.sub.90.ltoreq.212 .mu.m, and
D.sub.90.gtoreq.90 .mu.m; or
[0104] D.sub.99.5.ltoreq.425 .mu.m, D.sub.90.ltoreq.212 .mu.m, and
D.sub.90.gtoreq.90 .mu.m.
[0105] The particle size distribution of the sodium carbonate in
accordance with embodiment (E) can be determined by mechanical
sieving. This method is appreciated because of its easiness, broad
availability, and excellent repeatability. Mechanical sieving is
generally based on the mechanical separation of the various
fractions on a series of superimposed sieves. The analysis can be
made partly or fully in accordance with ASTM E 359-00 (reapproved
2005).sup..epsilon.1, the whole content of which being herein
incorporated by reference. ASTM E 359-00 (reapproved
2005).sup..epsilon.1 concerns various measurements made
specifically on sodium carbonate, notably sieve analysis. The
particle size distribution is advantageously determined with an
automatic mechanical sieving device, such Ro-Tap RX-29 sieve shaker
(as commercialized by W. S. Tyler Company). The sieves mounted on
the sieve shaker are advantageously in conformity with standard ISO
3310-1 or ASTM E-11, preferably with wire stainless steel circular
sieves with square meshes, metal mounting with a diameter 200 mm.
The device and its sieves are advantageously checked periodically
using a reference powder; the control frequency should be desirably
be as high as possible for early detection of any deviation, as
possibly resulting for damaged meshes. Typically, it is proceeded
as follows: the sieves are superimposed and assembled from top to
bottom by descending order of opening mesh; a fixed weight amount
of the powder to be investigated is weighed with an analytical
balance and placed on top of the widest sieve; by vibrating the
sieving machine, the powder material is conveyed through the
various sieves; the sieving operation is run for a fixed amount of
time; the residues on the sieves are weighed with an analytical
balance and related mathematically to the initial weight of
material. Notably D.sub.90 and D.sub.99.5 values can be calculated
from the residues weights. This calculation is generally made as
follows:
1) Calculate the weight percentage of the test specimen retained on
each sieve. 2) Express the weight percentage passing through each
sieve, and cumulated.
[0106] The results can be displayed on a graph were the
Y-coordinate represents the cumulative weight percent particles
retained on a particular sieve. The X-coordinate corresponds to
sieve size. The Y-value for a particular sieve can be determined by
adding the weight of the particles retained on that sieve plus the
weights of the particles retained on all larger sieves above it and
dividing the sum by the total weight of the sample.
[0107] The sieves can be ISO 3310-1 or ASTM E-11 test sieves having
a diameter of 200 mm, notably commercialized from LAVAL LAB Inc. A
certain suitable set of sieves is composed of eight ISO 3310-1 or
ASTM E-11 test sieves having a diameter of 200 mm, having the
following aperture size or ASTM opening designation: 1000 .mu.m
(ASTM No. 18), 500 .mu.m (ASTM No. 35), 250 .mu.m (ASTM No. 60),
180 .mu.m (ASTM No. 80), 125 .mu.m (ASTM (No. 120), 90 .mu.m (ASTM
No. 170), 63 .mu.m (ASTM No. 230) and 45 .mu.m (ASTM No. 325).
[0108] At the end of the sieving analysis, the weight fraction
caught on each screen can be calculated. .PHI..sub.i., the fraction
on sieve i, of size x.sub.i, is thus:
.phi. i = w i i = 1 n w i ##EQU00001##
wherein w.sub.i is the weight of powder collected on sieve i sample
weight
[0109] The percentage under the size x.sub.t P.sub.t is thus
defined as:
P t = i = 1 t - 1 .phi. i ##EQU00002##
[0110] To obtain the cumulative curve, P.sub.t, the percentage
under the size x.sub.t can be plotted versus x.sub.t. The curve can
be built by considering in each point the following slope:
( P x ) x = x t = .phi. t x t + 1 - x t ##EQU00003##
3) Determine D.sub.z values (0<z<100), e.g. determine
D.sub.90 and D.sub.99.5.
[0111] D.sub.z is defined as the abscissa of the curve for P=z/100,
i.e. z wt. % of the sample is under the size of D.sub.z.
[0112] D.sub.90 is defined as the abscissa of the curve for P=0.90,
i.e. 90 wt. % of the sample is under the size of D.sub.90.
[0113] D.sub.99.5 is defined as the abscissa of the curve for
P=0.995, i.e. 99.5 wt. % of the sample is under the size of
D.sub.99.5.
[0114] Exemplary Method for Measuring the Particule Size
Distribution, in Particular the D.sub.90 and D.sub.99.5, of
Particulate Na.sub.2CO.sub.3
[0115] Apparatus:
[0116] Mechanical sieving apparatus able to transmit combined
movements in the horizontal plane and shocks along the vertical
axis to a pile of superimposed sieves (apparatus used: RO-TAP RX-29
Model or equivalent, with 278 horizontal revolutions and 150 taps
per minute)
[0117] Series of circular sieves, wire stainless steel with square
meshes, metal mounting with a diameter 200 mm, in conformity with
NF ISO 3310-1 standard and periodically checked using a reference
powder.
[0118] Sieves superimposed by descending order of opening mesh
(size in .mu.m): 1000 .mu.m, 500 .mu.m, 250 .mu.m, 180 .mu.m, 125
.mu.m, 90 .mu.m, 63 .mu.m and 45 .mu.m. [0119] Analytical balance,
accuracy 0.01 g.
[0120] Method: [0121] Test Specimen: 70 g of powder weighed to 0.01
g. [0122] Transfer the test specimen on the pile of sieves and
position it in the apparatus [0123] Sieve for 15 minutes. [0124]
Weigh the content of each sieve to 0.01 g.
[0125] Calculation:
[0126] Calculate the weight percentage of the test specimen
retained on each sieve.
[0127] Express the weight percentage passing through each sieve,
and cumulated.
[0128] Determine by graphical interpolation the mesh opening
equivalent to the 90% and 99.5% cumulated weight percentage
(D.sub.90, D.sub.99.5).
[0129] The particle size distribution of the sodium carbonate used
in accordance with embodiment (E) is advantageously determined on a
sample which is representative of the whole sodium carbonate which
is used in said process. To achieve appropriate sampling, the
skilled person will advantageously rely upon all those sampling
recommendations which do form part of the general knowledge and are
broadly described in various encyclopaedias, including but not
limited to "Sampling", Reg. Davies, in "Kirk-Othmer Encyclopaedia
of Chemical Technology", online Ed. 2000, the whole content of
which is herein is incorporated by reference. Since sodium
carbonate can be viewed as a free-flowing powder, sampling
procedures suitable for stored free-flowing powders will be used
preferably.
[0130] Sodium carbonate is broadly commercially available, either
in the form of dense sodium carbonate or light sodium carbonate.
Light sodium carbonate, also called light soda ash, has generally a
free flowing density, as measured in accordance with ISO 903
standard, of between 0.48 kg/dm.sup.3 and 0.65 kg/dm.sup.3. Dense
sodium carbonate, commonly called dense soda ash, has generally a
free flowing density, as measured in accordance with ISO 903
standard, of from 0.90 kg/dm.sup.3 to 1.20 kg/dm.sup.3. In general,
neither the commercially available dense sodium carbonates nor the
commercially available light sodium carbonates have a particle size
distribution as required by embodiment (E). Yet, as will explained
below, it is easy for the skilled person, searching for obtaining a
sodium carbonate with the appropriate particle size requirements,
to obtain it.
[0131] Dense sodium carbonates having the particle size
distribution as required by present embodiment (E) can be notably
obtained by appropriate grinding and/or sieving dense sodium
carbonates having a particle size distribution not in accordance
with embodiment (E). Insofar as dense sodium carbonates are
concerned, methods including at least one grinding step followed by
at least one sieving step are preferred. As suitable grinders, it
can be notably cited jet mills such as helical jet mills, oval tube
jet mills, counterjet mills, fluidized bed jet mills, and ball and
plate jet mills, can notably be used. As suitable sieves, it can be
notably cited 710 .mu.m, 630 .mu.m, 500 .mu.m, 400 .mu.m, 300
.mu.m, 250 .mu.m, 200 .mu.m, 150 .mu.m and 125 .mu.m sieves.
[0132] Light sodium carbonates having the particle size
distribution as required in present embodiment (E) can also be
obtained by appropriate grinding and/or sieving light sodium
carbonates having a particle size distribution not in accordance
with embodiment (E). However, insofar as light sodium carbonates
are concerned, methods free of any grinding step are preferred;
such methods may include a sieving step or not. A particularly
preferred method for obtaining light sodium carbonates having the
particle size distribution in accordance with embodiment (E)
comprises selecting said light sodium carbonates among different
lots of one or more grades of commercially available light sodium
carbonates, as detailed below. The Applicant determined the
particle size distribution of numerous lots of commercially
available (unground) light sodium carbonates from different
sources, and observed that, among all these lots, none had a
D.sub.90 below 45 .mu.m; as a matter of fact, their D.sub.90 often
ranged usually from about 100 .mu.m to about 250 .mu.m, i.e. the
lots often complied with both requirements set forth for the
D.sub.90 in accordance with embodiment (E) of the present
invention. Concerning the D.sub.99.5 of the commercially available
light sodium carbonates, the Applicant observed surprisingly that
its variability from one lot to another was very high, including
when considering lots produced at relatively short intervals of
time by the same manufacturer in the same plant; it deduced wisely
therefrom that this variability could be exploited to its own
benefit, because, among the lots produced, certain had the
appropriate particle size requirements, while certain other lots of
the same commercial grade had a D.sub.99.5 above 710 .mu.m, not in
accordance with embodiment (E) of the present invention. Among the
tested sodium carbonates, SODASOLVAY.RTM. L sodium carbonate, as
produced notably in Dombasle or Rosignano plants, is particularly
attractive because a rather high fraction of this commercial grade
is formed by lots in accordance with the invention; thus, the
Applicant could very easily identify appropriate lots suitable for
use in accordance with embodiment (E) of the present invention.
[0133] An important and surprising benefit resulting from the use
of sodium carbonate powder meeting the requirements of embodiment
(E) is that it allows one to limit the amount of potassium
carbonate, and more generally of any other higher alkali metal
carbonate, to be used in the preparation of the PAEK. As higher
alkali metal carbonates other than potassium carbonate, it can be
particularly cited rubidium carbonate and caesium carbonate.
[0134] Thus, in accordance with embodiment (E), the molar ratio of
A/Na (wherein A designates either K, Cs or Rb or any combination
thereof) can be of at most 0.050 mol A/mol Na, preferably at most
0.020 mol A/mol Na, and more preferably at most 0.010 mol A/mol Na.
In an especially surprising particular sub-embodiment, the molar
ratio of A/Na is equal to 0 (i.e. the nucleophilic substitution
takes place in the absence of K, Cs and Rb). In another
sub-embodiment, the molar ratio of A/Na, although being maintained
at a low level (e.g. in accordance with the above specified upper
limits), is above 0, preferably of at least 0.001 mol A/mol Na,
more preferably of at least 0.002 mol A/mol Na and still more
preferably of at least 0.003 mol A/mol Na. Unlike the particle size
distribution of the sodium carbonate, the particle size
distribution of the potassium carbonate, when present, is not
important, although a slight additional improvement in terms of
polymerization kinetics might be observed when using a very finely
ground potassium carbonate.
[0135] In a particular sub-embodiment of embodiment (E), the method
for the preparation of a poly(aryletherketone) meets further the
technical limitations as met in accordance with previously
described embodiment (D).
EXAMPLES
Analytical Methods
DSC Conditions
[0136] DSC measurements were done according to ASTM D3418-03,
E1356-03, E793-06, E794-06 on TA Instruments DSC 2920 with nitrogen
as carrier gas (99.998% purity, 50 ml/min). Temperature and heat
flow calibrations were done using indium. Sample size was 5 to 7
mg. The weight was recorded.+-.0.01 mg.
[0137] The heat cycles were: [0138] 1st heat cycle: 50.00.degree.
C. to 380.00.degree. C. at 20.00.degree. C./min, isothermal at
380.00.degree. C. for 1 min. [0139] 1.sup.st cool cycle:
380.00.degree. C. to 50.00.degree. C. at 20.00.degree. C./min,
isothermal for 1 min. [0140] 2.sup.nd heat cycle: 50.00.degree. C.
to 380.00.degree. C. at 20.00.degree. C./min, isothermal at
380.00.degree. C. for 1 min.
[0141] The enthalpy of fusion was determined on the 2nd heat scan.
The melting of PEEK was taken as the area over a linear baseline
drawn from 220.degree. C. to a temperature above the last endotherm
(typically 370-380.degree. C.).
Melt Flow Index Measurement Conditions
[0142] Melt flow index was measured according to ASTM D1238-04 at
400.degree. C. with 2.16 kg load. The die had the following
dimensions: 2.0955 mm diameter and 8.000 mm length. A charge of 3 g
of dry polymer (dried at 170.degree. C. for 4 hours) was used.
MF.sub.10 is the melt flow index measured after the polymer has
been kept 10 minutes in the barrel. MF.sub.30 is the melt flow
index measured under the same conditions but after the polymer has
been kept in the barrel at 400.degree. C. for 30 minutes. MFR (melt
flow ratio) is the ratio of MF.sub.30/MF.sub.10 and reflects the
melt stability of the polymer. MFR .ltoreq.1 indicates an increase
of viscosity overtime.
RV Measurement Conditions
[0143] Reduced Viscosity (RV) was measured according ASTM D2857-95
(2007) at 25.degree. C. in concentrated sulfuric acid (1 wt.
%/vol). The viscometer tube was number 50 Cannon Fenske. The
solution used was prepared by dissolving 1.0000.+-.0.0004 g of
resin in 100 ml.+-.0.3 ml concentrated sulfuric acid (95-98%,
density=1.84). The concentration C in g/dl is equal to the polymer
weight in g divided by the volume in dl (100 ml=1 dl). In order to
facilitate the dissolution, ground powder (approx mean particle
size 200-600 .mu.m) was used. The sample was dissolved at room
temperature (no heating).
[0144] The solution was filtered on glass frit (medium porosity)
before use. The
[0145] RV was calculated as
RV = t so ln - t solvent t solvent * C ##EQU00004##
wherein t.sub.soln and t.sub.solvent are the efflux times measured
for the solution and the blank solvent, respectively. The average
of at least 3 measurements was used for efflux times. Under these
conditions, the efflux times should be longer than 200 s and, no
correction for kinetic energy was applied.
[0146] Since sulfonation of the polymer can occur in concentrated
sulfuric acid, the efflux time of the solution has to be measured
within the 3 hours after the preparation of the solution.
Determination of 2,4'-DFBP and 4-Monofluorobenzophenone in
4,4'-Difluorobenzophenone By Liquid Chromatographic Analysis
[0147] The HPLC method is carried out on a Agilent 1100 LC
instrument using a Supelco Discovery HS F5, 5 .mu.m, 25
cm.times.4.6 mm column. The analysis conditions were:
Mobile Phase: acetonitrile/deionized water Gradient: 60/40
acetonitrile/water for 5 minutes, increase to 100% acetonitrile in
a further 10 minutes. Flow rate: 1 ml/minute
Detection: UV 254 nm
Temperature: 50.degree. C.
Injection Volume: 5 .mu.l
[0148] The sample was prepared by dissolving about 0.01 g of
4,4'-DFBP in 100 ml of acetone.
[0149] The amount of 2,4'-difluorobenzophenone and
4-monofluorobenzophenone in 4,4'-difluorobenzophenone was
determined using a calibration with three external standards of
these commercially available compounds, of different
concentrations, to generate a calibration curve.
[0150] The retention time of 2,4'-DFBP was about 7.4 minutes and
7.1 minutes for 4-mono fluorobenzophenone. The retention time for
4,4'-DFBP was about 7.7 minutes.
[0151] Results are expressed as parts per million of the two
impurities.
Determination of the Purity of 4,4'-Difluorobenzophenone by Gas
Chromatography and of Chlorofluorobenzophenone in
4,4'-Difluorobenzophenone by Gas Chromatography
[0152] Gas chromatographic analysis was performed on an Agilent
HP6890 Gas Chromatograph, using an HP column: HP-5, 15 m.times.0.25
mm diameter, 0.25 micron film thickness and the running conditions
were:
Injector temperature: 290.degree. C. Detector temperature (FID):
300.degree. C. Oven ramp: 60.degree. C., hold for 1 minute, then to
325.degree. C. at 30 C/minute, 5 minute hold at 325.degree. C.
Split ratio: 60:1 Injection volume: 0.2 .mu.l Carrier gas flow
(helium): 1 ml/minute
[0153] The sample is prepared by dissolving 150 mg of
4,4'-difluorobenzophenone in 5 ml of acetone.
[0154] The GC retention time for 4,4-difluorobenzophenone is around
5.7 minutes, and about 7.0 minutes for mono-Cl,F-benzophenone.
[0155] The 4,4'-DFBP purity is quoted as an area %, calculated from
the GC peak areas in the area % table. The chlorofluorobenzophenone
impurity peaks were identified by GCMS analysis and their amounts
were estimated from their GC peak areas using external standards of
commercially available compounds and assuming that isomers had the
same response factor.
Determination of Chlorine Content in 4,4'-Difluorobenzophenone
[0156] Using forceps, a clean, dry combustion boat was placed onto
a microbalance, and the balance was zeroed. 1 mg of
4,4'-difluorobenzophenone sample was weighed into the boat and
weight was recorded to 0.001 mg. The combustion boat and sample
were placed in the introduction port of a Thermo Electron
Corporation ECS 1200 Halogen Analyzer, and the port was capped. The
sample weight was entered into the sample weight field on the
instrument computer. The sample analysis cycle was then started.
The sample was burned in a mixture of argon and oxygen and the
combustion products were carried by the combustion gas stream into
a titration cell. Hydrogen chloride produced from the combustion
was absorbed into the cell solution from the gas stream, and was
coulometrically titrated with silver ions. Total chlorine content
was displayed at the end of the titration.
[0157] The invention will now be illustrated by the following
non-limiting examples. In these examples, the amounts are indicated
as percentages by weight unless otherwise indicated.
Example 1
[0158] In a 500 ml 4-neck reaction flask fitted with a stirrer, a
N.sub.2 inlet dip tube, a Claisen adapter with a thermocouple
plunging in the reaction medium, and a Dean-Stark trap with a
condenser and a dry ice trap were introduced 175.00 g of
diphenylsulfone [meeting all the impurity limitations of embodiment
(D)], 28.00 g of p-hydroquinone, 57.12 g of 4,4'-DFBP containing
780 ppm 4-FBP and less than 40 ppm 2,4'-DFBP as measured by LC
(supplied by Jintan ChunFeng Chemical Co. and used without further
purification), 26.77 g of Na.sub.2CO.sub.3 (having a
D.sub.90.gtoreq.45 .mu.m, a D.sub.90.ltoreq.250 .mu.m and a
D.sub.99.5.ltoreq.710 .mu.m) and 1.80 g of very finely ground
K.sub.2CO.sub.3 (D.sub.50.ltoreq.45 .mu.m). The flask content was
evacuated under vacuum and then filled with house nitrogen 4 times
using a Firestone valve and then placed under a nitrogen purge (30
ml/min). 80.00 g of xylene were then introduced into the reactor
and the reaction mixture was heated slowly to 200.degree. C. (1
hour heating period). Xylene/water azeotrope started distilling off
at 163-170.degree. C. The reaction mixture was held at 200.degree.
C. for 30 minutes and then heated up to 250.degree. C., held at
250.degree. C. for 30 minutes, heated up to 310.degree. C. and held
at this temperature for 3 hours. Termination was carried out by
adding 1.42 g 4,4'-DFBP (of above-mentioned purity) and 2.21 g LiCl
to the reaction mixture and keeping the mixture at 310.degree. C.
for an additional 30 minutes. The reactor content was then poured
from the reactor into a SS pan and cooled. The solid was broken up
and ground through a 2 mm screen. DPS and salts were extracted from
the mixture with acetone and water and acidic water (pH=1). The pH
of the final wash water was .gtoreq.5. The polymer was dried at
120.degree. C. under vacuum. The polymer had a reduced viscosity
measured at 25.degree. C. in concentrated H.sub.2SO.sub.4 of 1.17.
The enthalpy of fusion measured on the 2.sup.nd heat cycle of the
DSC, determined as explained below, was 43.8 J/g.
Examples 2 to 8
[0159] Examples 2 to 8 were made using the same procedure as
Example 1 but substituting the 4,4'-DFBP used with different
4,4'-DFBP having different levels of 2,4'-DFBP and 4-FBP (supplied
by Jintan ChunFeng Chemical Co. or Navin Fluorine and used without
further purification). The reaction was stopped at different
reaction time to obtain polymer samples with different molecular
weights.
[0160] Examples 1 through 4 demonstrate that, using 4,4'-DFBP with
less than 750 ppm 2,4'-DFBP, polymer with good crystallinity level
can be made.
[0161] Comparative examples 5 through 8 show that, using 4,4'-DFBP
with more than 750 ppm 2,4'-DFBP, polymer with reduced
crystallinity level is obtained.
TABLE-US-00002 TABLE 1 Target .DELTA.H fusion .DELTA.H 2nd heat
Exam- GC fusion (68.0 - ple purity 4FBP 2,4'DFBP RV 2nd heat
26.6*RV) # (area %) (ppm) (ppm) (dl/g) (J/g) (J/g) 1 99.8 780
<40 1.17 43.8 36.88 2 99.8 1089 <40 0.84 47.7 45.66 3 99.8
780 307 1.13 38.8 37.94 4 99.8 780 323 0.70 51.1 49.38 C5 99.8 1512
788 0.80 44.7 46.72 C6 99.9 780 870 0.67 34.8 50.18 C7 99.8 780
1004 0.97 41.5 42.20 C8 99.8 780 1208 0.71 45.3 49.11
[0162] Surprisingly, the examples 1-4, while featuring a lower GC
purity level, gave better results compared to example C6. In other
words, impurities different from the 4FBP and 2,4'DFBP (that were
specifically detected in these examples) have minor or no impact at
all on the properties of the resulting polymers, and in particular
on their enthalpy of fusion.
[0163] The enthalpy of fusion from 2.sup.nd heat cycle in DSC is
shown in FIG. 1, which represents the graph of the enthalpy of
fusion expressed in J/g versus the reduced viscosity (RV) expressed
in dl/g, and where Examples 1-4 are Examples according to the
invention, Examples 5-8 are Comparative Examples and the
represented line corresponds to the target enthalpy of fusion.
Examples 10 and 11
[0164] Examples 10 and 11 were made using the same procedure as in
Example 1 but substituting the 4,4'-DFBP used with different
4,4'-DFBP (supplied by Jintan ChunFeng Chemical Co), containing
added 2-chloro-4'-fluorobenzophenone (supplied by DSL Chemicals,
Shangai) as indicated in Table 2. The melt stability was measured
by the ratio of melt flow at 400.degree. C. after 30 minutes over
the melt flow measured after 10 minutes. As shown, when the monomer
contains more than 5000 ppm of chlorofluorobenzophenone, the
polymer exhibits unacceptable melt stability (MFR 0.05). Preferred
MFR values include from 0.50 to 1.20.
[0165] It is expected that isomers of
2-chloro-4'-fluorobenzophenone would have a similar effect on melt
stability.
[0166] Example 11 (comparative) shows that high levels of
chlorofluorobenzophenone have a deleterious effect on melt
stability (MFR too low).
TABLE-US-00003 TABLE 2 GC 2-chloro-4'- Example purity 4FBP 24'DFBP
Fluorobenzo- [CI] RV MF10 # (area %) (ppm) (ppm) phenone (ppm) (wt
%) (dL/g) (g/10 min) MFR 1 99.8 780 <40 50 0.0008 1.17 3.28 0.66
2 99.9 1089 <40 50 0.0008 0.84 23.05 1.02 10 99.5 780 <40
3450 0.052 0.93 9.47 1.02 C11 99.2 780 <40 6650 0.101 0.83 19.86
0.05
[0167] As described above, the present invention has many facets.
In one facet, an advancement is described in that processes for
preparing a PAEK polymer by reacting a nucleophile with
4,4'-difluorobenzophenone (4,4'-DFBP) are improved through the use
of 4,4'-DFBP that meets one or more of the above purity conditions.
In another facet, improved PAEK polymers are produced using the
invention 4,4'-DFBP.
[0168] Additional aspects and other features of the present
invention will be set forth in part in the description that follows
and in part will become apparent to those having ordinary skill in
the art upon examination of the following or may be learned from
the practice of the present invention. The advantages of the
present invention may be realized and obtained as particularly
pointed out in the appended claims. As will be realized, the
present invention is capable of other and different embodiments,
and its several details are capable of modifications in various
obvious respects, all without departing from the present invention.
The description is to be regarded as illustrative in nature, and
not as restrictive.
[0169] The above written description of the invention provides a
manner and process of making and using it such that any person
skilled in this art is enabled to make and use the same, this
enablement being provided in particular for the subject matter of
the appended claims, which make up a part of the original
description.
[0170] As used herein, the phrases "selected from the group
consisting of," "chosen from," and the like include mixtures of the
specified materials. Terms such as "contain(s)" and the like as
used herein are open terms meaning `including at least` unless
otherwise specifically noted. Phrases such as "mention may be
made," etc. preface examples of materials that can be used and do
not limit the invention to the specific materials, etc.,
listed.
[0171] All references, patents, applications, tests, standards,
documents, publications, brochures, texts, articles, etc. mentioned
herein are incorporated herein by reference. Where a numerical
limit or range is stated, the endpoints are included. Also, all
values and subranges within a numerical limit or range are
specifically included as if explicitly written out.
[0172] The above description is presented to enable a person
skilled in the art to make and use the invention, and is provided
in the context of a particular application and its requirements.
Various modifications to the preferred embodiments will be readily
apparent to those skilled in the art, and the generic principles
defined herein may be applied to other embodiments and applications
without departing from the spirit and scope of the invention. Thus,
this invention is not intended to be limited to the embodiments
shown, but is to be accorded the widest scope consistent with the
principles and features disclosed herein. In this regard, certain
embodiments within the invention may not show every benefit of the
invention, considered broadly.
* * * * *