Note: Descriptions are shown in the official language in which they were submitted.
~VO 93/02122 2 1 1 t~ li 3 ^~ PCl`/US91/09020
COPOI~YEST~:RS FOR HIG}~ MODllLUS FIBERS
FIELD OF THE IN~lENq~ION
The present invention relates to high modulus
polyester fibers. More specifically, the invention
relates to a novel polyester ~omposition and fibers made
from that composition wherein the fibers have excellent
tensile properties at room temperature and at elevated
temperatures.
~ACRGROUND
Poly~ethylene terephthalate) (HPET"), nylons, such
a~ Nylon 6 and Nylon 66, and Rayon are the predomin~nt
syntheti~ polymers used in making tire yarn and tire
cord. Each polymer has it~ own advantages and
disadvantages. The most widely used ~f the~e, PET, h~s
high tensile ~trength and tensile modulus, a high glass
transition temperature, and good stability. Nylon has
exceilent strength, toughne~s and fatigue re~i~t~nce, but
has the ~erious disadvantage of "flat ~potting" in tires
because of its low glass transition temperature and a
tendency to creep. Rayon retains a higher percentage of
its tensile properties at elevated temper~ture~ (e.g.,
150C). Considerable research h~ ~een carried out in an
effort to improve the properties of the~e m~terial~.
One approach has been to try to synthesize a
polye~ter which ha~ a higher tensile strength ~nd tensile
modulus than PET and retains the~e propesties ~t elevated
temperatures. Such a material would retain the inherent
advantages of polyesters in general, such as ~hemical
stability. Alternative polyesters that have been made
and evalua~ed in~lude poly(ethylene naphthalate) (~PEN"),
W O 93/02122 PC~r/US91/09020 ~..
~ 3r,~ 3 ~J 2
the condensation polymer of ethylene glycol and 2,6-
naphthalenedicarboxylic acid, and the polymer of 4,4'-
bibenzoic acid and ethylene glycol. Copolymers in which
4,4'-bibenzoic acid and/or 2,6-naphthalene dicarboxylic
acid are included 8S comonomexs in PET have been reported
in European Patent Application ~o. 202,631. A copolymer
of 4,4'-bibenzoic acid, 2,6-naphthalenedicarboxylic acid,
and ethylene glycol was reported in Japanese Published
Patent Application 50-135333 to be particularly useful
for making tire yarn when the mole ratio of 4,4 -
bibenzoic acid to 2,6-naphthalenedicarboxylic acid is
less than about 1:4. This reference states that when
4,4'-bibenzoic acid makes up more than about 20 mole~ of
the diacids in the co~position, the composition is of no
value as a tire yarn because it has a low so.tenin~
temperature and a low Young~s modulus (tensile modulus)
This conclusion is supported by examples which indicate
that the softening te~perature has decreased from 275C
for PEN to 238~C in the copolymer in which monomer units
derived from 4,4'~bibenzoic acid make up 25% of the
monomer units derived from the two diacîds (i.e. the
ratio of monomer units derived from 4,4'-bibenzoic acid
to those derived from 2,6-naphthalenedicarboxylic acid is
1:3).
In view of the tea~hings of the above-named patent,
it is surprising that copolymers of 2,6-
naphthalene~icarboxylic acid and 4,4'-bibenzoic acid with
ethylene glycol in which the mole ratio of monomer units
derived from 4,4'-bibenzoic acid to those derived from
2,6-naphthalenedicarboxylic acid is grsater than 1:3
yield fibers which have excellent tensile propexties,
both at room temperature and at elevated temperatures.
W O 93/02122 2 1 1 3 ~ 3 9 PC~r/US91/09020
SUnfMU~RY OF THE INnJENrTION
The present invention is a copolyester composition
comprising monomer units derived from 4,4 -bibenzoic
acid, 2,6-naphthalenedicarboxylic acid and ethylene
S glycol, hut ~ot including monomer units derived from
terephthalic acid in a num~er greater than about 50% of
all the diacid ~omponents; the ratio of 4,4 -bibenzoi~
acid to 2,6-naphthale~edicarboxylic a~id is greater than
1s3. Preferred compositions have a ~rystalline melting
point less than about 320C and an inherent viscosity of
at least about 0.8 dl/g when measured at 25~C and 0.1%
concentration on a weight/volume basis in a solution of
egual parts by volume of h~xafluoroisopropanol and
pentafluorophenol. The best compositions for melt
~pinning of high modulus fibers compri~e the mono~er
unit~ derived from 4,4'-bibenzoic acid and 2,6-
naphthalenedicarboxylic acid in a ratio of about 40:60 to
about 60:40, with the best results being obtained with
about equimolar amounts of the two dia~id monQmers~
To make polymer ~ui~a~le for melt ~pinn ng, an
intermediats molecular weight ~opolye~ter having an
inherent vi~osity in the range of ~bout O~S dl/g up to
about 1.0 dltg is made by melt polymeriz~tion and is th~n
heated in the solid ~tate to a temperature of about 220C
to about 270~ for a time sufficient to increa~e the
inherent viscosity of the polymer to at least about 1~0
dl/g~ The intermediate ~ole~ular weight ~opolye~ter ~an
~e made in two steps by (1) heating a molten mixture of
about 40 to about 60 parts on a mole ~asi~ of dialkyl
2,6-naphthalenedicarboxylate, about 60 to about 40 parts
of dialkyl 4,4'-bibenzoate, and at least about 100 parts
WO93/02122 PCT/US91/0~20
3&V 4
of ethylene glycol with an ester interchange catalyst to
a temperature of about 200c until sufficient by-product
alcohol is distilled off to yield a low molecular weiqht
polyester, and (2) heating the low molecular weight
polyester in the molten gtate with a polycondensation
cataly~t to a temperature of about 240C to about 290C
to yield an intenmediate molecular weight polyester
having ~n inherent viscosity in the range of about 0.8
dl/g to about 1.0 dl/g. The preferred dialkyl esters of
the two diacids are the dimethyl esters, and the by-
product alcohol is then methanol.
$he copolyesters of the present invention are melt
~pun into higb modulus fi~ers in a ~ingle ~tep (i.e.,
without the need for a post-spinning draw ~tep) by
~pinning ~t a high draw down ratio with a relatively low
aelt temper~ture. As the melt temperature is increased;
a higher dr~w down ratio i~ needed to obtain an as-spun
fiber with a high modulus. Fibers made by this process
have a modulus of at least about 150 gpd; the most
preferred composition has a modulus of at least about 200
gpd.
~RIEF D SCR~PTION OF THE DRAWING
~ igure 1 i8 a plot of the ~elting temperature of the
copolyesters of the cur~ent invention as ~ function of
the composition. The composition i8 expres~ed as the
~ole % of 4,4'-bibenzoic acid of the two diacid monomer
units combined.
Figure 2 is a plot of the fi~er modulu~ as a
function of the draw down ratio for the composition
containing eguimolar amounts of the two diacids at
WO93/02122 2 1 1 3 S ~ ~ PCT/US91/09020
several different melt temperatures.
Figure 3 is a plot of the logarithm of the draw down
ratio vs. fiber modulus for the compositions having 4,4'-
bibenzoic acid and 2,6-naphthalenedicarboxylic acid in a
50:50 mole ratio and a 60:40 mole ratio.
Figure 4 shows the stress-strain curves at room
temperature ~nd 150C for single fibers of PET and for
the copolyester of the current invention having the two
diacids in a 50:50 mole ratio~
DETAII.ED DESCR~PTION OF THE INVENTION
The present invention discloses polyester
compositions comprising monomer units derived from 2~6~
n~phthalenedicarboxylic acid, 4,4'-bibenzoic acid and
ethylene glycol in which the ratio of the num~er of
monomer units derived from 4,4'-bibenzoic acid to those
derived from 2,6-naphthalenedicarboxylic acid i8 greater
than about l:3. These polymers are useful in making
films, ~haped articles, ~s by injection ~r ~mpression
molding, and high.modulus fibers. Compo~itions in which
the melting temperature of the polymer is le~s than about
320C ~re preferred for uses in which melt processing is
required.
The polymers of the present invention ~re
particularly useful in making high modulus fiberQ.
Fiber~ can be readily made by melt spinning when the
ratio of monomer units derived from 4,4'-bibenzoic acid
to those derived from 2,6-naphthalenedicarboxylic acid is
greater than l:3 as long as the melting temperature is
less than about 320~C. For fiber spinning~ better
WO93/02122 PCT/US91/090~0
C
~ 6
results are obtained when the ratio of monomer units
derived from the two diacids is in the range of about
40:60 to about 60:40. The best results are obtained when
the two diacids are present in about equal amounts.
Other monomers may also be- included in the
compositions useful for melt ~pinning as long as they
don't alter the properties to the extent that fibers can
no longer be melt spun or that the fiber properties are
no longer useful. Thus, for example, 2,6-naphthalene-
dicarboxyli~ acid monomer units, ~hown as Structure I,
~re the subject of this invention, but monomer units
based on 2,6-naphthalenediol (II), 2-hydroxy-6-naphthoic
~cid (III) or mixtures thereof
o o
~ 0~ _0~
o
11 lli
may be included in the ~omposition. Similarly, ~,4'-
bibenzoic acid monomer u~its (IV) are ~ssential to the
composition disclosed herein, but monomer u~it~ deriv~d
from 4,4'-~iphenol (V), 4-hydroxy-4'-biphenycarboxylic
~~id (VI) and mixtures thereof may al~o be included.
W093/02122 2 1 1 3 ~ PCT/US91/OgO20
_c~_o~o ~_
~v V V'
Substitution of non-reactive group~ for ~ome of the
hydrogen atoms on the aromatic ri~gs al80 iS within the
scope of the present invention~ Suitable substituents
include halogen atoms, such as fluorine, chlori.ne,
bromine or iodine; lower alkyl groups h~ving up to about
four c~rbon ~to~s, such as methyl, ethyl, n-butyl, or
tert-butyl; ~nd lower alkoxy groups having up to about
four carbon atoms, such as methoxy, ethoxy or butoxy.
Minor amounts of linkages other than ester linkage~, as
for ex~mple amide linkages, are also within the scope of
the inventi~n. Thus, the amine ~alogs of the ~lcohol
and phenol monomers may also be included ~ low levels;
examples include ethylenediamine ænd 4-aminobenzoic ~cid.
Terephthalic acid.may also be includ~d as a comonomer as
long ~ ~onomer unit~ derived from ter~phthali~ acid do
not make up more than about 50~ ~f the diacid mo~omer
units.
In addition small amounts of higher glycol~, 2S for
example 1,3-propanediol, 1,4-butanediol, and psopylene
glycol, may be substituted for ethylene glycol. ~inally,
other ~ifunctional or multifun~tional mon~mers not
specifically named above may be included.
To achieve the high molecular weight necessary for
good fiber properties, the number of hydroxyl groups in
W093/02122 PCT/US91/~020
~ ,~,?~ 3 j 8
the starting monomers must be about equal to the number
of carboxylic acid groups. Thus, for a composition in
which pure 2,6-naphthalenedicarboxylic acid and pure
4,4 -bibenzoic acid are the acid monomers, the amount of
ethylene glycol on a mole basis must be about equal to
the combined ~mounts of the two diacids. Substitution of
other monomers for the diacids may result in changes in
the ~mount of glycol needed to achieve tbe stoichiometry
needed for making a high molecular weight polyester.
The monomers utilized in this composition are
readily made by methods well known in the art. The
diacid monomers may also be purchased as the free acids
or as the dimetbyl esters from commercial ~uppliers of
fi~e chemic~ls. Ethylene glycol is commercially
lS available from several m~nufacturers.
The crystalline melting points of the copolyesters
of 2,6-naphthalenedicarboxylic acid, 4,4 -bibenzoic acid
~nd ethylene glycol vary according to the relative
amounts of the two diacids. The melting points of
~ever~l of these compositions ~re ~hown in Table 1 (after
Example 6). The melting points are plotted in Figure 1
as a function of the amount of 4,4 -bibenzoic acid
(measured as the mole % of the combined diacids). When
the mole % of 4,4'-bibenzoic acid i8 in the range of
about 40~ to ~bout 60%, the melting point of the
copolyester is in the range of about 260C to about
305-C. This is the preferred range for melt spinning of
fibers.
At the upper end of the range (about 30SC), thermal
decomposition of the polymer reduces the molecular weight
rapidly enough that high tensile properties of fibers are
WO g3/02122 2 ~ 1 3 ~ ~3 .~3 PCT/US91/0~20
difficult to attain. At the low end of the temperature
range, the polyester has lower crystallinity, resulting
in poorer fiber tensile properties. The best combination
of thermal properties and crystallinity for melt spinning
of fibers lie~ in the middle of this range. The melting
point and cry~t~llinity (a~ measured by ~H~ in the DSC
data ~hown in Table 1) appear to go through a minimum
when the mole % of 4,4'-bibenzoic acid is within the
range of about 20% to about 40%.
The copolyesters di~closed herein can be made by
~ethods commonly u~ed for making polyesters. These
methods include interfacial condensation of the glycols
with the ~cid chlorides of the diacids. The polymers can
~l~o be D~de by aelt condensation of the glycol~ with the
~cids or ~lkyl esters of the ~cid~. These methods are
generally well known in the art.
In order to obtain the desired fiber properties, it
is necessary to achieve a high molecular weigbt, ~s
indicated by a high inherent viscosity (~I.V.~). The
~pun f~bers preferably have an I.V. of at least about 0.8
dl/g wXen mea~ured at 25C at 0.1% concentration on a
weight/volume b~sis in a ~olution of egu~l part~ by
volume of hexafluoroisopropanol and pentafluorophenol.
In general, in order to achie~e this I.V. after spinning,
it i~ preferable to melt spin a polymer having an I.V. of
at least about l.0 dl/g before spinning so that thermal
decomposition and hydrolysis due to tr~ces of moisture do
not reduce the I.V. of the spun fiber to a value of less
than about 0.8 dl/g. Melt ~pinning of polymers having an
I.V. of less than about l.0 dl/g can be carried out
succe~sfully, but moisture must be excluded more
carefully and the residence time of the polymer at
W O 93/02122 PC~r/US91/09020
~ & 3~
elevated temperature must be reduced.
Tt has been discovered that a polymer having such a
high I.V. can be made by first making an intermed~ate
molecular weight polyester having an I.V. in the range of
S about 0.5 to about 1.0 dl/g and then raising the
molecular weight by 13olid ~;tate polymerization 80 that
the I.V. is at least about 1.0 dl/g.
The preferred method of making an intermediate
molecular weight polyester for solid state polymerization
i8 to carry out a melt polymerization in two stages. The
first stage of the melt polymerization consists of the
ester interchange reaction of dialkyl e~ters of the two
diacids with ~thylene glycol in the temperature range of
about 200C to about 240-C in the presence of an ester,
interchange c~talyst. The ester interchange reaction i~
carried out under an inert atmosphere (e.g. nitrogen)
under anhydrous conditions. Dimethyl esters are the
preferred dialkyl esters. The diesters are mixed in the
de~ired ratio with an excess of ethylene glycol in the
pre~ence of the ester interchange catalyst. Catalysts
which catalyze ester interchange reactions are well known
in ~he art and include ~ewis acids ~nd bases, zinc
acetate, calcium acetat~, titani~m tetrabutoxide,
germanium tetraethoxide, and mangane~e acetate.
Manganese acetate i~ preferred. As the ester interchange
reaction proceeds, by-product alcohol is removed by
distillation~ ~hen the preferred dimethyl esters are
used, the by-product is methanol. The ester interchange
reaction is normally complete in 1PSS than about ten
hours, preferably two to three hours, and leads to a very
low molecular weight material, having an I.V. of less
than about 0.2 dl/g.
WO93/02122 PCT/US9t/09020
21 ~ r~
The second stage of the melt polymerization
consists of a polycondensation reaction, wherein a
polycondensation catalyst is added and the ~emperature is
raised into the range of about 240C to about 290C.
This reaction is preferably carried out at reduced
pressure, as ethylene glycol must be removed to achieve
the desired intermediate molecular weight. Catalysts for
the polycondensation reaction are ~ell known in the art
and include Lewis acids and base~, polyphosphoric acid,
antimony trioxide, titanium tetraalkoxides, germanium
tetraethoxide, organophosphates, organophosphites, and
mixtures thereof, with a ~ixture of triphenylphosphate
and antimony trioxide being preferred. The
polycondensation reaction is carried out until the I.V.
5 i8 in the range of abo;t 0.5 dl/g to about 1.0 dl/g and
can normally be completed in less than about ten hours,
preferably in two to three hours.
The intermediate molecular weight polyester is
ground to a powder or is pelletized prior to solid state
polymerization. The powder is dried and is then heated
in the range of about 220C to about 270C under an inert
atmosphere (e.g., a nitroqen stream) or in a vacuum f or
a ti~e sufficient to raise the I.V. to at least about 1.0
dl~g. A typical time needed to achieve ~ high molecular
weight i8 in the range of a~out 16 hour~ to a~out 24
hours. The time needed to achieve ~igh mole~ular weight
can be longer or shorter, depending on the temp~xature
~nd the mole~ular weight of the powder. In general, the
higher the temperature, the faster the reaction pro~eeds.
However, the temperature cannot ~e so high that the
polymer agglomerates or ~oalesces, as that would
interfere with the progress of the polymerization.
WO93/02122 PCT/US91/09020
& 3
12
The high I.V. polyester is particularly suitable for
melt spinning into high modulus industrial fibers. Melt
spinning processes are well known in the art and are
widely used in the manufacture of PET fibers.
The polyester of the present invention is dried
immediately before spinning, preferably by warminq in a
dry atmosphere or under vacuum. The polyester is then
passed into a heated zone, where it is heated to ~
temperature above the melting point. The molten polymer
i~ then filtered by conventional methods and i5 extrud~d
through one or more spinnerettes, each having one or more
holes. As the polymer is extruded, it is taken up on a
reel at a much higher ~peed than the extrusion ~peed.
The ratio of the take-up speed t~ the extrusion ~peed is
the draw down ratio. As it is extruded, the fiber is~
quenched (cooled) in a gss or air stream, ~o that the
point at which drawing of the fiber takes place is
localized.
It has been found that the copolyesters of the
pre~ent inYention unexp~ctedly exhi~it ~elt spinning
~havior that i~ characteristic either of onventional
poly~er~ or of thermotropic liquid ~rystalline polymers,
depending on the m~lt ~pinning co~ditions. Conventional
fibers mu~t normally be drawn in a ~eparate post-~pinning
step in order to attain high tensile properties.
Thermotropic liquid crystalli~e polymers normally can be
spun into high modulus fibers without a subsequent
drawing step; however, liquid ~rystalline polymers
normally cannot be drawn.
With the copolyesters of the present invention,
excellent tensile properties can be achieved in a single
W O 93/02122 2 1 1 3 ~ 3 ~ PC~r/US91/09020
13
spinning step without a subsequent drawing step by
maintaining a relatively low melt temperature and a high
draw down ratio. When the melt temperature is just above
the melting point of the copolyester, excellent tensile
properties can be obtained at relatively low draw down
ratios. As the melt temperature is increased, ~ higher
draw down ratio is needed to ~hieve high tensile
properties. These data ~re presented in detail in
Examples 9-27 and in Table 2 for the copolyester
containing approxLmately equimolar amounts of 2,6-
naphthalenedicarboxylic acid and 4,4'-bibenzoi~ acid.
Analogous results have been achieved for the
~opolyesters containing different amounts of the two
diacids. For example, Figure 3 shows ~ plot of the
logarithm of the draw down ratio as a function of fi~er
modulus for the composition containing equimolar amounts
of the two diacid components (melting point about 285C)
at 300C and also for the co~position containing monomer
units derived from 4,4 -bi~enzoic acid and 2,6-
naphthalenedicarboxylic acid in a 60:40 mole ratio(melting point about 304-) at 315C and 334C. It can be
~een that for both compositions~ the ~s-spun modulus
increases with draw down ratio~ It ean al~o be ~een that
a~ the melt temperature in~reases for the 60:40
composition, a higher draw down ratio i~ needed to
achieve ~ particular modulus. It is also apparent in
Figure 3 that the composition containing equLmolar
~mounts of the two dia~ids yields a higher modulus fiber
than the 60:40 c~mposition~
The fact that the fiber modulus is high in the as-
spun fiber when the melt temperature is kept low and the
draw down ratio is kept high may be attributed to stress
~ 3~3 PCT/US91/09020
14
durinq spinning. Higher melt viscosity, which results
f~om lower temperatures, and higher draw down ratios both
cause increased stress during spinning, and may increase
the tendency of the elongated polymer chains to orient
themselves in the direction of the fiber. It thus
appears that high stress results in increased tensile
modulus in the as-spun fiber.
When the copolyesters are melt spun under conditions
that result in high tensile properties in the as-spun
fiber, the fibers in general can not be drawn appreciably
(perhaps a few %). However, if the fibers are spun under
conditions of low stress so that the tensile properties
are relatively low, then the as-spun fibers behave more
like conventional fibers in that they can be drAwn at
elevated temperatures in a ~ubsequen~ step to increa~e
the tensile properties. The fiber tensile properties
Improve on drawing, but they are not as high as tho~e
that are achieved under high stress (i.e. low melt
temperature and high draw down ratio).
The fact that the fiber csn be spun under condition~
that lead to high tensile properties in a single ~pinning
step without a subsequent drawing ~ep has great ~alue
because it simplifies the process for manufacturing
fiber. For compari~on, PET is ~pun in a continuous
proc~ss, but the proces~ i5 more complex than that of the
present invention because of the nece~ity of drawing the
PET fiber after spinning.
A valuable chara~teristic of the fibers of the
present invention is that they have excellent ~ensile
properties, both at room temperature and at elevated
temperatures. For example, fibers made of the 50:50
W093/02t22 PCT/US91/09020
2 3 ~
copolymer of 4,4 -bibenzoic acid and 2,6-
naphthalenedicarboxylic acid have a tensile modulus more
than twice that of a commercial PET tire yarn (Trevira~
Type 800 high denier industrial tire yarn, manufactured
by ~oechst Celanese Corporation), both at room
t~mperature (382 gpd vs. 115 gpd) and at 150C (154 gpd
vs. 57 gpd)-
.
Another valuable property of the fibers of thecurrent invention is that they exhibit reduced hot air
shrinkage in comparison with commercial PET tire yarns.
Thus, yarn made of the 50:50 copolymer has a hot air
shrinkage of about 0.7 - 0.8~, whereas Trevira~ D240 high
denier industrial yarn from Hoechst Celanese Corporation
has a hot air shrinkage of about 5.4%.
Fibers and yarns made using the copolyesters taught
herein can be treated in subseguent steps after spinning
~uch as other polyester fibers (e.g. PET). Thus the
fibers or yarns can be treated with one or more finishes,
depending on the ultimate end use. The yarns can also be
twisted and plied together to make tire cords using
conventional techniques.
The copolyesters of the present invention have other
end uses besides industri~l fibers and yarns. For
example, the copolyesters csn be extruded as a monofil,
a high denier single filament fiber. The copolyesters
can also be injection molded into shaped articles with
high tensile properties or extruded as tspes. Films,
including biaxially oriented films, can also be made from
these copolyesters by methods well known in the art.
Shaped articles can also be made by compression molding.
This is particularly useful for the very high melting
WO93~02122 ~ PCT/US91/~9020
'~3 ~
16
compositions.
In order that those skilled in the art can more
fully understand this invention, the following non-
limiting examples are provided.
SE~AM~LE 1
In a l-liter three-necked res~n flask equipped with
a nitrogen inlet and ou~let, thermometer, condenser and
mechanical stirrer were placed 29 grams (O.11888 moles)
of dimethyl 2,6-naphthalenedicarboxylate, 32.1 gram~
10(0.11888 moles) of dimethyl 4,4'-bibenzoate, 36.77 grams
(O.5930 moles) of ethylene glycol and 0.070 grams of
manganese acets~e tetrahydrate. The mixture was heat:ed
at 220 C for 2.5 hours while distilling out methanol.
Polycondensation catalysts consisting of 0.0675 grams of,
15triphenylphosphate and 0.02259 grams of antimony trioxide
were added to the mi~ture. The resulting mixture was
heated with ~tirring to 270C. Yacuum was ~hen ~pplied,
and the temperature wa~ raised to 283-C and held at that
temperature for 2.5 hours. The resulti-ng polymer was
cooled to room temperature to obtain a copolyestex with
an intermediate molecular weight having an I.V. of 0.85
dl/g ~ determined at 25 degrees and 0.1% ~oncentration
on a weight/volume ba~is in a ~olution of equal part~ by
volume of hexafluoroisopropanol ~nd penta1uorophQnol.
~5 The polymer had a melting point of 287C and a heat of
fusion of 44.6 j/g ~s measured by DoS~C~
The intermediate molecular weight polymer was ground
until it could be sifted through a No. 20 mesh screen.
The powder was then ~olid ~tate polymerized at 220
~0 degrees C for 24 hours under a reduced pressure to attain
a polyester with an increased molecular weight having an
WO93/02122 2 1 ~ i '? ~ PCT/US91~09020
17
I.V. of l.38 dl/g under the conditions described above.
The melting point was 288 degrees and the heat of fusion
was 62 j/g.
EXAMPLES 2-6
Other polymer compositions made from ethylene
glycol, 4,4'-bibenzoic acid, and 2,6-
naphthalenedicarboxylic acid were made accordin~ to the
method of Example l. The thermal proper~ies of these
compo~itions, including the 50:50 4,4'-bibenzoic acid:
2,6-naphthalenedicarboxylic acid composition of Example
1, are ~ummarized in Table l. The melting p~ints are
plotted in Figure 1 as a function of the amount of 4,4'-
bibenzoic acid, measured as a mole % of the two diacids.
TAB~E 1
.
~olo ~ I.V~ 5~p(~) ~q ~Bt
~pl~ al/q) ( oc) ( ~c) (~
.50 1.37 285- None 62
_. . __ _ ...
? o a. 58 265- 99~ 7
- 3 20 1.25 _ 238- 123-
20 ~ 40 N.D.~3) 263- 126 44
, .-- ...... . . _ _
1.40 304- ~n~ CO
. . .- . .
100 363 None 89
:
(1) Mole ~ of 4,4'-bibenzoic acid, oxpre~sed AB the ~ole 3 of 4,4'-bibenzoic ~cid and 2~6-n~phthalenedicsrbcxylic acid
c~bined.
~2) Endoth-rm peak tcmp~ratur~ by DSC.
(3) In~oluble in pentafluorophenol/hex~fluoroasoprop~nol
solution. Not Dotermined.
c1J~r ~3 Pcr/usgl/ngo20
18
EXAMPLE 7
A sample of polymer having the composition of
Example 1 and having an I.V. of 1.32 was dried under
va~uum overnight at 130C. The polymer was melt ~pun at
a melt temperature of 297C and a throughput of 0.128
g/min. through 8 O. 020" diameter capillary to yield a
single filament fiber. The fiber was quenched in air
before being taken up at 175 m/min to give 6.6 dpf fiber.
Thi~ corresponded to a draw down ratio at spinning of
360. Single fiber tensile properties were measured using
ASTM test method D 3822. The tests were carried out at
3" guage length and 60% strain rate. The fiber tensile
properties, expressed ~s tenacity in gpd (T)/~ elongation
~E)/modulus in gpd (M), were T/E/M - 11.6 gpd/3.8%/382
gpd. ~he fiber could not be drawn further over a hot
~hoe.
E~CAMPI.E 8
Another ~ample of polymer having the ~ame
composition as that of Example 7 ~nd having ~n I.V. of
1.15 dl/g was extruded in a ~L~ilar manner to that
described in Example 1 u~ing a melt temperature of 283C
~nd ~n extrusion rate of 0.161 g/min. Fiber of 5~8 dpf
was taken up at 2~0 m/min. Thi~ corresponded to a draw
down ratio at ~pinning of 409 and gave filaments with
tensile properties of T/E/M = 8~4 gpd/4.1%/406 gpd when
mea~ured according to the method~ set forth in Example 7.
. .~r T,.'T,.'`,'~ ,T~,~ T T ~ .S~
WO93/02122 21 1 3 & ~ 9 PCT/US91/09020
19
EXAMPLES 9-27
Another sample of polymer having the composition of
Example l and an I.V. of l.46 was dried prior to
spinning. The polymer was extruded in the same manner as
S in Example 7, except that the melt temperature during
spinning was varied and fiber samples were collected at
different take up speeds. The ~ingle fiber tensile
properties and fiber draw down ratio are shown in Table
2. The tensile properties were measured according to the
methods cited in Example 7.
WO 93/02122 P~/US9l/09020
T~LBLE 2
~-n~
Proporti~s
Xolt ~-~p ~k~ up ~(gpd)/~(~) Dr-w
5 ~ ~ pl - ~dog C. )(~/~iD) DPF/~(gpd)DOWD R~t~o
9 31~- 25 722.2/82~87 33
317- 50 342;3/4~111 70
_
11 317- 100 20__3.3/29~149 120
12 31~- 200 5.95.2/a.3/223 402
I
0 13 317- 330 6.0S .~/5.8/264 395
1~ 308- 2567 _ _ 1.8/96/67 36
lS 308- S02.6/19~153 59
I
16 308 100 144.0/6.0/201 17S
7 308 - 200 8.67.1/6.7~269 275
1~ 308- 330 4 89.5/5.2/338 490
19- 298- 25 ~2.0J15/108 52
299- S0 274.~ 235 88
21 299- 100 13~-3~4.5/267 180
22 299- 200 - 5.98.7/4.9/315 ~00
I , _.
1 23 299 330 3.510.7/4.8/345 680
~4 290- 25 462.9/9.8/178 52
I . .
290- 50 305-4/5.4/285 _ 79
26 289~ 100 139.2~5.6/322 190
I .
1 27 289 200 ~.01~.2/~.S/366 340
These data ~how that fiber ~ensile properties of
tenacity snd modulus increa~e both with increasing draw
down ratio and with decreasing ~pinnins melt temperature.
For example, when the copolyester i~ spun at a ~elt
temperature of 29QC, which is only about 5~C higher than
the melting point, the spun fiber has a modulus of about
285 gpd at a draw down ratio of about 79 (Exdmple 25).
When the melt temperature of the same polymer i8 about
317~C, the modulus of the spun fi~er is about 149 gpd at
a draw down ratio of about 120 (Example 11), but at a
W,O 93/02122 2 1 1 3 ~ 3 9 PC~r/US91/09020
draw down ratio of a~out 400, the modulus of the spun
fiber is in the range of about 223 to 264 gpd (Examples
12 and 13). It can also be seen in Table 2 that the best
tensile properties are obtained at the lowest melt
temperatures and the highest draw down ratios. The fiber
modulus v8. draw down ratio i~; plotted in Figure 2 for
thi~ polymer at ~everal different melt temperatures. The
general trend is again apparent in~Figure 2 that higher
draw down ratios are needed at higher melt temperatures
to achieve high tensile properties.
Three samples made at the lowest draw down ratio and
the higher spinning temperatures, Examples 9, 14 and 19,
could be drawn over a hot ~hoe ~t 200C to give fiber
with increa~ed tensile properties. The other fiber
~mples could not be drawn appreciably. The improved
tensile properties of the dr~wn fiber~ ~re shown in Table
3.
TABLE 3
T~ns~le Properties of Dr~wn F~b~rs
2 0 ~Prop~rt~o~
~AMP~ DRAW RAS~O ~I!(gpæ ~ ) J~l(gp )
r~ 9~ __ -6.0tlO.~/228
I , .
14 ,, ~ 2.l _ _ 5.o/8.1!198
~9 , _ 1.4 ,,, ___ __ 4~7/3.5/240
WO93/0212~ 6 ~ PCT/US91/09020
EXAMP~E 28
The tensile properties of three copolyester
compositions at elevated temperatures were evaluated by
measuring the fiber tensile properties first at room
temperature as described in Example 7 and then in a
heated atmosphere at 150C. A ~ample of a ~ingle
filament of a commercial polyester tire yarn, Trevira~
Type 800 high denier industrial tire yarn, manufactured
by Hoechst Celanese Corporation, was run under the ~ame
conditions for compari~on. The results are ~hown in
Table 4.
In addition, a ~ample of fiber grade PE~ polymer was
melt spun into ~ingle fil~ment fibers using the same
equipment as was used for ~pinning single fil~ment fiber
~amples of the polymer of the pre~ent invention. The
polye~ter had an I.V. of 0.92 dl/g when measured at 8%
concentration in o-chlorop~enol at 25C. The I.V. of the
~ame polymer ~ample was measured as l.22 dl/g at 0~1%
concentration on a weight/volume basis in a ~olution of
egual volumes of hex~fluoroisopropanol ~nd
pentafluorophenol at 25C. After ~pinning, the single
fil~ment PET fiber was drawn over two hot shoes to fully
develop the tensil~ properties. The fiber wa~ the~ heat
set in an o~en at 200C under nitrogen for 30 minute~ in
~5 a rack in which the fiber was placed with 2% ~train. The
tensile propertie~ of thiæ ~PET Control" are al~o shown
in Ta~le 4. The stress-~train curves for the ~ET Control
and for the 50: 50 copolymer at room temperature and at
150~C are shown in Fiqure 4.
wo g3/02l22 2 1 1 3 ~ ~ ~ PCT/US91/09020
TABLE ~.
Tensile Properties of Copolyesters as ~ Functio~ of
Temperature
~en~ PrODert~ T~C/H)
S ~oo ~p r~tur~ 150 C
. ..
40t60 NDAsJ~ 5 8 gpd~2 5~32~ gpd 2 ~ gpd/1 8~135 gpd
.
S0~50 NDA~BBA~ 11.6gpd~3.8~/382 gpd 5.8 qpd/4.0~/~5~9pd
~0~0 NDAt~A~ 3.0 gp~/~. 8~/178 gpd Not M ~ur-d
Sr v~r ~ 8.5gpd/13.~/115 gpd 5.4 gpd/lS S~/57 gpd
sr~ ~oo .
. . . ____
~t Control lo.o 9pd/s.~ 7o ~ 6.0 ~ /9.6~37 ~
~NDA = 2,6-naphthalenedicarboxylic acid
8BA - 4,4'-bibenzoic acid
EXAMP~É 29
A ~ample of copolyester having the composition of
Example 1 and having 1.36 I.V. was dried at 130C under
vacuum overnight. The polymer was melted in a 1~
diameter extruder, and the extrudate was metered using a
conventional melt pump to the 8pin~ing pack where it was
filtered through 70/120 ~hattered metal. The melt at
289-C was extruded through a 20 hole annular spinnerette
with 0.020" diameter capillaries. Crossflow quench was
applied to the emerging filaments to provide a stable
~pinning enviroI~ment by localizing the fiber draw point,
producing a stable spinning process which yielded fiber
with low denier variability along its length~ The yarn
was dressed with a spin finish before passing around a
~y~tem of godets. It was finally taken up on a Leesona
type winder. The polymer throughput was 7.06 g~min. The
,
wo 93/02l22~6 39 PGT/US91/~020
24
210 denier yarn taken up at 300 m/min (draw down ratio =
224) had tensile properties of T/E/M = 9.5 gpd/5.2~/295
gpd. That taken up at 400 m/min (draw down ratio = ~98)
had tensile properties of T/E/M = 10.6 gpd/4.9%/321 gpd.
The spinning melt temperature was carefully ~elected to
be as low as possible, but not so low as to preclude good
runnability of the spinning process. It was also found
that a 2% hot ~tretch at 200C ~mproved yarn tensile
properties from T/E/M = 9.3 gpd/5.9~/267 gpd to 10.5
gpd/4.1~/300 gpd. Yarns were tested with a twist at 10"
length and at 60% strain rate, using ASTM test method D
8B5.
E~AMPLE 30
A sample of dried copolyester having approximately~
equimolar ~mounts of the two diacids and an I.V. of 1.36
was melted and extrudéd through a glot die 0.2S0" long
and 0.005" wide at 0.3 g/min. The extrudate was cooled
in ~ir and the resulting tape taken up at ~low ~peed.
The tènsile properties of the tape samples were measured
using ASTM test method D 882 and are shown in Table 5.
For comparison, the tensile properties of a sample of
Vectra~ liquid crystalline poly~er, manufactured by
~oechst Celanese Corporation, which was extruded into
tape in a similar manner, are tenacity, 69 kpsi;
elongation, 2.3%; modulus, 3.5 kkpsi.
WO g3/02122 PCr/USgl/09020
-~` 2 1 .L ~ ~i ~ 3
TABLE 5
T~Pe Dimensions
M~lt T~ke- Dr~w Tensil- ProPerties
S~p up Width Thickne-s Down
(-C) ~/JLin (inch~-) (~1-) Ratio T(kpsi)~E(~)/M(kkpsi)
297- 5 0 070 1 00 17 9 43 3/2 1/3 0
290- S 0 200 1 30 4 8 34 7/3 2tl 7
291- 4 0 080 1 54 10.1 34._~2 3/2 3
28'~- 10 0 060 1 10 18.9 67.2/3.6~2.9
ESAMP~E 31
A copolyester with inherent viscosity of 1.21 dl/g,
prepared according to the method of Example 1, was
injection molded into 1/8" x 3/8" x 2-1/2" tensile and
flexural bars uRing a Plasticor Model 64 Injection
Molding Apparatus at 310-C. The following mechanica~
properties were measured using ASTM te~t methods D 638
and D 790: tensile strength, 6.9 Ksi; modulus, 645 ~si;
elongation to break, 1.28%; flexural strength at break,
13.84 Ksi; flexural strength at 5% ~train, 17.97 Rsi; and
flexural modulus, 560 Xsi. The moduluQ of ~everal other
commercial materials was measured for comparison: PET
molding resin with ~.V. 0.76 dl/g, 317 Xsi; CELANEX~ 2002
polybutylen~ terephthalate, 370 ~si; and Nylon 66, 172
~8i. These modulus values were ~ignificantly lower than
the modulus of 64~ Ksi for the copolyester of the pre~ent
invention.
E~AMPLE 32
Hot air shrinkage measurements were carried out on
a yarn sample made according to the method of Example 29
using the composition containing equLmolar amounts of the
two diacids. Measurements were performed.by heating a
W093/02t22 PCT/US91/~20
26
measured length of yarn with no stress or strain for 30
minutes in an oven at 3500F, coolin~ the ~mple to room
temperature, and then determining the % change in length.
Comparative measurements were also carried out using the
S same method on a sample of Trevira~ D240 high denier
industrial yarn from ~oechst Celanese Corporation. The
yarn of the current invention exhibited a hot air
hrinkage of 0.7 - 0.8~ where~s Trevira~ D240 exhibited
a hot air ~hrinkage of 5.4%.
It is to be understood that the above-described
~mbodiments of the invention are illustrative only and
that modification throughout may occur to one skilled in
the ~rt. Accordingly, thi~ invention is not to be
regarded as limited to the embodiments disclo~ed herein
but i~ to be limited and defined only by the appended
claims.
