Note: Descriptions are shown in the official language in which they were submitted.
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212328
BIO~I D~ODUhUS pOLYTr8TE3'~t Y~1 p0lt
T~Rg CORZlB ~D~D CO~ED09IT$$
1. ~~ og ~~ zrrv~r~rzoN t
Thin invention relates to polyethyl~ne
aaphthalate (PEN) multifilament yarn and other yarns '
grade from eim,ilarly rigid monomer combinations with
extremely high modulua, good tenacity, and low
shrinkage particularly useful for the textile
reinforcement of tires. The P8N yarn of this invention
provides enhanced modulus and dimensional stability
when compared to conventionally processed p$N yarns. A
1o process for production of the mufti-filament PST yarn
ie an aspect of this invention.
a. ~~~~~ OF RELATED ART
Currently, polyethylene terephthalate (PET>
' filaments are co~nonZy used in industrial applicatiane
i5 including radial tire bodies, conveyor belts, seat
baits, V belts and hoeing. However, higher modulus and
dimenBional stability is preferred in more demanding
applications such ae bodies of monoply high pertornance
tires and ie required in the belts oP radial paesez~ger
2o tires. Dimensional stability is defined ae the darn oL
the elongation at ~.5 g/d (39.7 mN/dtex) and shrinkage,
U.9. Patent 3,516,832 to Bhima et ai. provides rubber
articles rein.torced with PEN of good dimensional
stability and. tenacity and U.6. Patent 3,929,18Q to
25 Kawase et al. provides a tire with PEN used as a
carcass reinforcement. However, these patents are
concerned with conventionally processed PBN of low
undrawn birefringence and hence do not achieve the full
property potential of this material ae ie the object of
3o this invention. The ~eame is true of British Pa.tant .._
1,445,464 to Hamana et al. which teaches optimized
drawing of conventionally spun PBN. U.S. Patent
4,OOO,a39 to Hamana et al, provides a process for
producing a high melting point, heat resistant undrawn
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pEN for electrically insulating fabrics. Since these
materials were prepared under high stress conditions
favoring high. cryetallinity or at least highly
nucleated structures, they lack drawability and
s cannot attain. high moduZus for the applications
contemplated herein. A product for the same application
is provided i,n U. S . 4, 001, 4'79 to Hama.na et ai . , which
is concerned with partially oriented yarns of high
elongation arid low tenacity.
14 BUI~ARY OR THE ~jVFNTION
The: yarns of thi~ invention are prepared by
spinning PAN or other semi-crystalline polyester
polymers made: from similarly rigid monomer combinations
to a state off' optimum amorphous orientation and
13 crystallini.t~~. The invention is accomplished by
selection of process parameters to form an uadrawn
polyester yarn of birefringence at least: 0.030. The
spun yarn is then hots drawn to a total draw ratio of
between x.5/1 and 6.0/1 with the resulting drawn eemi-
2o crystalline ~~olyeeter yarn having Tg greater than 100°C
and a melting pciat elevation at least ~''C. The
preferred yarn has a tenacity at leant 6.5 g/d (5'7.4
mN/dtex), diatenrioaal stability (ERBL f Shrinkage) of
lees than 5~, sad shrinkage 4~ or less.
25 They resulting yarn exhibits surprisingly high
modulue and tenacity together with low ~hrinkage when
compared to ~~rior art yarns.
B,~~z~R nAQC~RIpTION OF TEL DFtlltR_ INGS
Fic~. 1 represents a comparison of modules at
30 a tenacity o!: 6.2 g/d (54.7 mN/dtex) for the Pa~N yarns
of Examples ~'~. and ~ .
DSSCFtIISTION OF T ~ PRTs~'ERRED EMBODTMENT
ThE~ polyester multifilament yarn of the .
present inve=ition provides high modules, high. , .._
3s dimensional ~~tability and good tenacity,
characterietj.ce which are extremely desirable when this
material ie j.ncorporated as fibrous reinforcement into
rubber cornpo~iitee such as tires. PEN multifilament
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yarns or other yarns of polyester polymers made Irom
similarly rigid monomer combinations can be used
advantageously to reinforce two parts of a radial
passenger tine, the carca9s and the belt. Currently,
s passenger tine carcasses are reinforced primarily by
polyethylene terephthalate. Two tire characteristics
xhich are cox~troiled by the carcass cord property of
dimensional e~tability (modulue at a given shrinkage)
are sidewall indentations and tire handling. The high
1o modulus and d.imeneional stability of the P$N or other
polyester yarns of this invention relative to ~BT and
prior art p~ yarns means that tires with carcasses
reinforced with the yarns of thin invention will
exhibit lower' eidewall indentation and betCer handling
is behavior. The. yarns of this invention are also a
desirable reinforcement material because of their high
glass transition temperature (Tgy greater than 100°C,
i . a . 1~ 0°C for P$N, compared to a Tg Qf 80°C for PST .
Ths high Tg will result in lower cord heat generation
z0 over a widex temperature range relative to P$T tires,
resulting in longer tire lifetimes and overall cooler
tire operating temperatures. zn addition, since modulus
tends to drop precipitou~ly at temperatures above Tg,
the yarns of this invention will maintain modulus over
Zs a wider temperature range than PST. All of the above
mentioned advantages will be of critical importaac~e
when yarns of this invention are used to reinforce high
performance tires since this application requires low
cord heat generation and high modulue, especially at
30 elevated operating temperatures characteristic of high
speed perfora;ance driving.
PSIf multifilameat yarns and other polyester
yarns of thi~ invention can also be used to reinforce
the belts of radial passenger tires and the carcaes~ee . w
35 of radial truck tires. Currently steel ie used for
these applications since B$T possesses insufficient
strength and modulus for a gives cord diameter. The
high modulue of PEN relative to PST, and the additional
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__ 212638
4
modulus advan,tageg of th~ P$N of this invention will
make pSN an ideal material to be used as a steel
substitute.
The polyethylene naphthalate yarn of the
s invention contains at least 90 aiol percent polyethylene
naphthalate. Ia a preferred embodiment, the polyester
is substantially all polyethylene naphthalate.
Alternatively, the polyester may incorporate as
copolymer unite minor amounts of units derived from one
l0 or more eater-forming ingredients other than ethylene
glycol and 2,6 naphthy~,ene dicarboxylic acid or their
derivatives.
Illustrative examples of other ester forming
ingredient~ which may be copolymerized with the
1s polyethylene r~aphthalate unite include glycole such as
1,3-prvpanediol, 1,4-butanediol, 1,6-hexanadivl, etc.,
and dicarboxylic acids such as terephthalic acid,
isophthalic acid, hexahydroterephthalic acid, etilbeae
dicarboxylic acid, bibenzoic acid, adipic acid, eebacic
2o acid, azelaic acid, etc.
Other polyester yarns of the invention can
be prepared to contain polyester polymer made from
suitable combinations of rigid and flexible monomers
providing the resulting polymer is melt-epinnable, is
is ~emi-crystalline, and has a Tg greater than 100°.
Exampler of rigid monoa~ars include dicarboxylic acids
such ae ~,6-r~aphthaleae dicarboxyliC acid,
2,7-naphthale;4e dicarboxylic acid, Biphenyl
dicarboxylic ~~cid, etilbene dicarboxylic acid and
3o terephthalic ~~cid; dihydroxy compounds such as
hydroquinone, biphenol, p-xylene glycol, 2,4
cyclohexanedimethanol, neopentylene glycol; and
hydroxycarbox,~rlic acid such as P-hydroxybenzoic acid
and 7-hydroxy~-~-naphthvic acid. Examples of flexible
3S monomers inchide dicarboxylic aside such ae oxalic
acid, euccini~: acid, adipic acid, sebacic acid, and
dihydroxy corny?ounds such as ethylene glycol, 1,3
AMENDED SHEET
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propanediol, 1,4 butanediol, 1,6 hexaned:.ol. It is
important that the thermal stability of the polymer
above its melting point be sufficient to allow melt
processing without excessive degradation.
s 'rhs mufti-filament yarn of the present
invention coranonly possesses a denier per fila,~ent of
about 1 tv 20 (e. g. about 3 to iG), and commonly
consists of about 6 to 600 continuous filaments (e. g.
about 20 to 400 continuous filaments). The denier per
filament and the number of continuous filaments present
in the yarn m~,y be varied widely as will be apparent to
those skilled in the art.
Th~s mufti-filament yarn is particularly
suited for us~,e in industrial applications wherein high
is strength paly~eeter fibers have bees utilized in the
prior art. '
The fibers are particularly suited for use in
. environatenta where elevated temperatures (e.g. 100°Cy I
are encountered. Not only.dvea the fila,mentaxy material
2o provide enhanned rnodulus but it undergoes a very low
degree of ahr:.nkage for a high modulue r-Lbrous
thermoplastic.
The unexpected dimensional stability
advantage seems to originate from the foxznatior_ of a
2s unique rnorpho:Logy during spinning which arises from the
cryetallizati«n of highly oriented amorphous regions
characte-rized by as undrar~m birefringence of at least
0.03, preferaJ5ly 0.03 to C.30. This crystallization
occurs in either the drawing stage or the spinning
30 stage depending oa the level of stress imposed during
spinning. =f f:oo much stress is applied during
spinning, tha undrawn yarae tend to Lack drawability
and character:lstically exhibit melting points greater
than 290°C fox' PEN. The characterization parameters ~-
35 referred to hsarein may conveniently be determined by
testing the muitifilament yarn which consists of
s~ubetantially parallel filaments.
1. BIREBRINGBNCB - Birefringence was
AMENDED SHEET
~~J
~ a 1 lu as
CA 02126328 2001-08-29
- 6 -
extinction band is not visible the purple colored ha.-:~:
should be used for this measurement.
2. DENSITY - Densities were determined in a
n-heptane/carbon tetrachloride density gradient colu:~r. a~
23°C. The gradient column was prepared and calibrated
according to ASTM D1505-68.
3. MELTING POINT - Melting points were
determined with a Perkin-Elmer*Differential Scanning
Calorimeter (DSC) from the maxima of the endotherm
resulting from scanning a 10 mg sample at 20°C per
minute. Tg is to be taken under the same experimental
conditions as the inflection point in the change heat
capacity associated with the glass transition
temperature. Melting point evaluation for drawn yarns
( ~'~ Tm) is defined as:
~1 _ X11
where Tml is the melting point of the drawn yarn of
interest and Tmll is the melting point of a yarn which is
pre-melted and rapidly cooled in the DSC before
2o analysis.
4. INTRINSIC VISCOSITY - Intrinsic viscosity
(IV) of the polymer and yarn is a convenient measure of
the degree of polymerization and molecular weight. I~~~ is
determined by measurement of relative solution viscosity
(~ r) in a mixture of phenol and tetrachloroethane (60/40
by weight) solvents. ~ r is the ratio of the flow tire
of a PEN/solvent solution to the flow time of pure
solvent through a standard capillary. IV is calculated
by extrapolation of relative solution viscosity data to a
3o concentration of zero.
5. PHYSICAL PROPERTIES - The tensile
properties referred to herein were determined through the
utilization of an Instron*tensile tester using a 10 inc!~
gauge length and a strain rate of 120 percent per
minute. All tensile measurements were made at roots
temperature. Dimensional stability refers to the level
of stress achieved at a given shrinkage. In the tire
* trademark
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the level of stress achieved at a given shrinkage. In
the tire indu,etry, dimensional stability is defined ae
the sum of elongation at a specified load plus
shrinkage. Fc~r the present case, the elongation at a
s ap~cified load (EASL) is derived from the initial
modulue data using the following equation:
EA6L - 454/Modulus (g/d)
It ig well known that tenacity and madulue
increase with, increasing draw-ratio. while higher
io tenacity per se ie almost always highly desirable, the
high extensicn ratios are often net achievable due to
yarn quality problems or to excessive shrinkage.
Materials of this invention po~sees high levels of
modulus for a given level of tenacity. This ie
is quantified as the LT parameter, by ratioing L-5 to _
tenacity as follows:
LT ~~ ((L-5)4/T5.16) 1000
L-5 or~LA9$-5 is a measure of modulue defiaad ae load
in g/d at 5f elongation. The materials of this
Zo invention have LT at lea~t 25. If L-5 ig not measurable
because of yarn elongatione less than 5~ the yarns will
be pre-relaxed at elevated temperatures before testing .
to increase elongation beyond 5~.
Shrinkage values were determined is
25 accordance~with ATM D885 after one minute at 177°C
employing a constraining force o~ 0.05 g/denier (0.44
mN/dtex)-.
2dentified hereafter ie a description of a
process which has been found to be capable of forming
30 the improved ,yarn of the present invention. Tha yarn
product claimed hereafter ie not to be limited by the
parameters of the process which followra.
The melt-epinnable poly~eter it supplied to
an extrusion ~spinaerette at a temperature above its ~~-
3s melting point and below the temperature at which the
polymer d~gradee substantially. The residexlce time at
this stage is kept to a minimum and the temperature
should not ri;ae above 350°C, preferably 320°C.
AMENDED SHEET
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21263~~
8
The extruded filaments then traverse a
conventional yarn solidification $vne where quench air
impinges on the spun yarn thereby freezing in dea:irabia
internal structural features and preventing the
filaments fro:a fusing to one another. Tha
solidification zone preferably comprises (a) a retarded
cooling zone ca~mprising a gaseous atmosphere heated at
a te~aperature to at least 150°C, preferably 150 to
500°C, and (b) ~a cooling zone adjacent to said rstarded
to cooling sons wh,erain said yarn is rapidly cooled and
solidified in a. blown air atmosphere. The ksy to the
current proceso~ is to adjust processing conditions to
aohievv a highly oriented undrawn yarn of birafringenee
at last 0.03 a,nd an elevated melting point of ~-Z5°C,
is preferably 3-23°C. For pEN a malting point of 265 to
290°C, prafsrab.ly 268 to 288°C must be achieved. Ono
skilled in the art can aehiavo this by adjusting the
following eondi,tiona: length and temperature of the
retarded eoolin.g tone adjacent to the spinnorstte,
2o diameter of ths. apron~rette holes, method of blowing
the q~,iench, gue~nah air velocity, and drawdown in the
solidifioation ions. The speed of withdrawal of the
yarn from the aoiidification zone is an important
parameter affecaing the stress on the spun fiber, and
25 should ba adjus;ted to yi~ld the desired '
characteristics,. Tha spur: yarn is then drawn by
conventioAal means in either a continuous or
non-continuous process to yield a drawn yarn with Tg
greater than iC~o°c and a melting point elevation at
30 least 8°c, preferably 8 to 15°C. ~t is preferred to
have the following drawn yarn properties: tenacity at
least s.5 g/d (57.4 mN/dtox), preferably at least 7.5
g/d (66.Z mN/dt.ax): dimensional stability (EA3L +
shrinkage) of less than 5~~ and shrinkage of a~ .or , .._
3s leas.
y Ei~ - ( CondPnRATIVE )
~'A~~~EN~ undrawn yarn was produced by axtxvding
AMENDED SHEET
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._ ' ' Jr ' 2~2G328
9
3Z filaments through a spinnerette with orifices of
length 0.042 in~ch$s (o.107cm) and of width 0.021 inches
(0.053 cm) at a. thruput or 23.2 cc/min. The filaments
were soiiditied, in an air quenching column and'taken up
at winder spaed,s of 305 m/min.
This yarn was drawn in two stages using
conventional heated rolls. The undrawn yarn properties,
drawn yarn propartieo, and drawing conditions are
gumr~arised in Table I.
to The yarn of this example, which was prepared
conventionally from an undrawn yarn of 0 n m o.Io04,
possesses poorer modulus than the yarns of this
invention as evidenced by LT less than 25. Also'the
dimensional stability parameter (EA8L + shrinkage) of
i3 8.3 is higher than that of yarns of this invention,
indicating poorer dimensional stability (see Exnmpl~
zii) .
TAB I ,
A. UNDRAW~T Yet
20 ~ n 0.004
Tmnacity (g/d) 0.6 (5.3 mN%dtex)
Modulus (g/d) 18.6 (164 mN/dtex)
Tm (°C) 268
25 ~. DRAW N YARN
Dr aw Ratio 6 . 3
Roll 1 (C) 140
Roll 2 (~C) 157
Roll 3 (C) RT
30
n 0.426
Tenacit;Y (g/d) 6.Z (54.? mN/dtsx)
Modulus (g/d) 176 (1553 mN/dtox)
Tm (C) 272 , .._
35 Shrinka~~e (~) 5.7
EASL + ;shrink (~) 8.3
d Tm(C) ?
AMENDED SHEET
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p'i(1 :3:iEif3 - +~l~j 8~) '?:3~1JV4F~:~: # 13
-..' '_ ~_ ~ 2.~~632g
to
~~i,PLB II
PEN yarns were produced by extruding seven
filaments through a gpiru~erette with orifices' of length
s 0.036 inches (0.091 cm) and width of 0.016 inches
( 4 . O G 1 cm) a t a thruput of 9 . 6 c;1~3 /min . The f i l amen t s
were solidified in an air quenching calum~ and taken up
at winder speedy ranging from ??C-5000 m/min.;Theae
yarns were drawn in two stages using a heating pate it
to draw zone two. The undrawn yarn properties, drawn yarn
properties, and' drawing conditions are suuanarized ir.
Table II.
Visual inspection of the data in this
example illustrates that for yarns drawn to a~;given
13 tenacity, modulus increases with increasing spinning
speed and with drawn and undraam melting point. This is
reflected in the increasing LT parameter with'
iacreaeiag spinning speed.~Undrawr. birefringence alone
~ie not Sufficient to characterize the yarns of this
.
2o invention. Since this parameter is insensitive to
morphological cl~angee which occur at high spirir.ing
stresses, both melting point ane~ birefringence mu~c be
used to detirte the scope of this invention. In ordex zo
compare the data of thie~ example with that of ,
25 comparative Example I, the modulua values of
Table IZ were interpolated to 6.2 g/d (54.'1 mN/dtex),
tenacitp sad plotted ve epi:v-~ing speed (Fig. 1.) . This
ana7,yeie clearly shows the advar_tagea of the yarns of
this invention relative to prior art yarns.
i
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212328
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2126328
12
~sXAMPLB I2I
Then undrawn yarns of Exar~~ple II spun at X70
m/min a.-~d 4oc~0 m/min were drawn to their ultimate
limit.
s The: 770 m/min sample was drawn in ore stage
using an oven in the draw zone and the 4000 rr./rnin
sample waB di:awn in two stages using a heated plate in
the second di:aw zone.
ThE; drawn yarn properties and drawing
io conditions are summarized in Table III. This example
shows that ttie yarns of this invention poesegs
extremely hic_~h modulue, high tenacity, and low
shrinkage ma~.ing them desirable for in-rubber
applications.
is TAHLF III
A~RAWN YARN
-u~ s~&.$ ~rn/min)
,~Q 4000
2o Draw Ratio 5 . 9 Z . 0
Roll 1 I;Cl 120 95
Oven ( C ) 17 0 _ _
Roll 2 I:C) RT ~ RT
Heating Plate (C) -- 24a
2s Roll 3 (Cl -- RT
Ten-acit~~ tg/d) (mN/dtex) 10,3 (90.9) 7.6 (67.1)
Modulua (g/d) (mN/dtex) 362 (3204) 4?7 (3680)
Shrinkac; a ( ~r ) 3 . 5 c 1
30 EASL + 6~'.:rink ( ~ ) 4 . 8 <2 .1
L-5 (g/C;) (mN/dtex) B.3 (73.3) ?.5 (66.2)
LT 28 90
EXAMPLE ~ , .._
3s This: example shows that undrawn yarns of high
birefringence, rnodulue, and melting point can be
produced at e~pinning speeds slower than those of
Bxample II, thereby yielding a more commercially
AMENDED SHEET
RCS.\.(>\:E-ayysD'C:\CHH\''? ....., ,.'___.,'Bvl'y:j'3
y,,...F;)~3;i":fi)4y''() :3W1t3 - +v;3 E3J '?a3:),)~C-CE~:~:N1E~
._ ' y rJ 2126~32~
13
feasible process for those lacking high speed
capabilities. P~1 yarns were produced by extru3ing
seven f~.lamerite through a epinnerette with orifices of
length 0.069 inches sad width 0.030 inches at a thruput
s of 9.6 cc/mix:. The filaments ware eolidi~ied in an air
quenching column and taken up at winder speeds ranging
from 410 m/m!.n to 2500 m/min. The properties of these
yarns are sur;rnarized in Table zv.
'x'~LFi V
~~~,-~,rp 9PE8D fM/M~N~
2500
~n 0..178 0.159 0.192 0.232 0.233 0.226
is
Tenac i,ty ~ 2 . 1 2 . 0 2 . 6 3 . 8 4 . 0 4 . 5
tg/d)
(mN/dtex)(18.5) (1~.~) (22~9) (33.5) (35.3) (39.7)
Modulue 64 58 63 114 143 158
(g/d)
(mN/dtex) (565) (512) (556) (1006) (1x62) (1395)
°C) 269 267 Z68 279 291 292
AMENDED SHEET
~' P
. _....
