Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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A DRAWN POLYESTER YARN HAVING A HIGH TENACITY
A HIGH INITIAL MODULUS AND A LOW SHRINKAGE
Field of the Invention
The instant invention is directed to a drawn polyester yarn
having a high tenacity, a high initial modulus and a low shrinkage.
Backqround of the_Invention
Since fiber-forming, melt-spinnable, synthetic polymers were
introduced, fiber manufacturers have Iooked for ways to increase the
strength and stability properties of the fibers made from those
polymers. The additional strength and stability propertie~ of th~
fibers are needed so that applications beyond textile uses could be
opened for their products. Such non-textile uses (also known as
"industrial uses") include: tire cord; sewing thread; sail cloth;
cloth, webs or mats used for road bed construction or other
geo-textlle applications; industrial belts; composite materials;
architectural fabrics; reinforcement in hoses; laminated fabrics;
ropes; and the likQ.
Originally, rayon was used in some o~ these industrial uses.
Thereafter, nylon supplanted rayon as the material of choice. In the
1970's, conventional polyesters, such as polyethylene terephthalate,
were introduced into competition against nylon. In about 1985, higher
per~ormance polyesters, l.e. higher strength and greater stability,
were introduced.
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A brief review of some of the patent prior art, summarized
below, indicate~ that three general areag have been investigated as
possible ways of enhancing the strength and stability properties of
these synthetic fibers. Those general areas include: processes
directed to drawing; processes directed to the polymer; and processes
directed to the spinning. Hereinafter, the term "drawing" shall refer
to the heating and stretching performed on an as-spun yarn. The term
"treatment to the polymer" shall refer to those things done to the
polymer prior to spinning. The term "spinning" shall refer to
processes for forming fllaments from polymer, but excluding drawing.
The processes directed to drawing are a~ follows:
In U. S. Patent No. 3,090,997, multistage drawing of polyamides,
~or use as tire cords, ls dlsclosed. The fibers (nylon) are melt-spun
in a conventional fashion. Thereafter, spun fibers are drawn in a
threQ-stage process (drawn, then heated, then drawn again) to obtain a
drawn nylon having the following properties: tenacity ranging from
10.4 to ll.l grams per denier ~gpd); elongation ranging from 12.9 to
17.1%J and initial modulus o~ 48 to 71 gpd/100%.
In U. S. Patent No. 3,303,169, there 1~ dlsclo~ed a slngl--stage
drawing procese ~or polyamides that yields high modulus, high
tenacity, and low ~hrinkage polyamide yarns. The spun polyamide is
drawn and heated to at lea~t 115C to obtain a yarn having: tenacity
in the range of 5 to 8.7 gpd; elongation ranging from 16.2 to 30.3~:
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initial modulus of 28 to 5sgpd/100%; and shrinkaga ranging from 3.5 to
15%.
In U. S. Patent No. 3,966,867, a two-stage drawing process for
polyethylene terephthalate having a relative viscosity of 1.5 to 1.7
i5 disclosed. In the first stage, the fibers are sub;ected to a
temperature between 70 and 100C and a draw ratio of 3.8 to 4.2. In
the second stage, the fibers are subjected to a temperature between
210 and 250C and a draw ratio, in the aggregate of the first draw
ratio and second draw ratio, in the range of 5.6 to 6.1. The dxawn
yarn obtained has the following properties: tenacity, 7.5 and 9.5
gpd: elongation, approximately 2 to 5% at a load of 5 gpd; elongation
at break, 9 to 15~: and shrinkage, 1 to 4~.
In U. S. Patent No. 4,003,974, polyethylene terephthalate spun
yarn, having an HRV of 24 to 28, is heated to 75 to 250c while being
drawn, i8 then passed over a heated draw roll, and finally relaxed.
The drawn yarn has the following properties: tenacity, 7.5 to 9 gpd;
shrinkage, about 4~; elongatlon at break, 12 to 20S; and load bearing
capaclty o~ 3 to 5 gpd at 7~ elongation.
Those processes directed to enhancing yarn properties by
treatment to the polymer are as follows:
In U. S. Patent Nos. 4,690,866 and 4,867,963, the intrinsic
viscosity ~I.V.) o~ the polyethylene terephthalate is greater than
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0.90. In U. S. Patent No. 4,690,868, the as-spun (undrawn) fiber
properties are as follows: elongat~on at break, 52 to 193%:
birefriengence, 0.0626 to 0.136; and degree of crystallinity,
19.3 to 36.8%. The drawn fiber properties are as follows:
tenacity, 5.9 to 8.3 gpd: elongation, 10.1 to 24.4~: and dry
shrinkage (at 210C), 0.5 to 10.3~. In U. S. Patent No. 4,867,936,
the drawn fiber properties are follows: tenacity, about 8.5 gpd:
elongation at break, about 9.9%: and shrinkage tat 177C), about
5.7~.
Those processes directed to spinnlng are as follows:
In U. S Patent No. 3,053,611, polyethylene terephthalate after
leavlng the sp~nneret is heated to 220C in a spinnlng shaft two
meters long. Thereafter, cold water is sprayed onto the fibers in a
second shaft. The fibers are taken up at a speed of 1,600 meters per
minute ~mpm) and are subsequently drawn to obtain a tenaclty of 3.5
gpd.
In U. S. Patent No. 3,291,880, a polyamlde is ~pun ~rom a
splnneret and then cooled to about 15C, then the fiber ls sprayed
wlth llve steam. The as-spun fiber has a low orlentatlon and a low
birefriengence.
In U. S. Patent No. 3,361,~59, a synthetlc organlc polymer is
~pun into a fiber. AB the flbers exit the spinneret, they are
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subjected to ~controlled retarded cooling". This cooling is
c~ducted over the firs~ seven inches from the spinneret. At the
top (i.e. adjacent the spinneret), the temperature is ~00C and at
the bottom (i.e. approximately 7 inches from the spinneret), the
minimum te~perature is 132C. The as-spun yarn has a low
birefriengence (ll to 35 x 10 3) and drawn yarn properties are as
follows: tenacity, 6.9 to 9.4 gpd; initial modulus, 107 to 140
gpd/100%; and elongation at break, 7.7 to 9.5%.
In u. s. Patent Nos. 3,936,253 and 3,969,462, there is disclosed
the use o~ a heated shroud (ranging in length from one-half foot to
two feet) with temperatures ranging from about 115 to 460C. In the
former, the temperature is greater at the top of the shroud than at
the bottom. The drawn yarn propertles of the former are as follows:
tenacity, 9.25 gpd; elongation, about 13.5%; and shrinkage, about
9.5%. In the latter, the temperature is constant within the shroud and
the drawn yarn properties are as follows: tenacity, 8 to 11 gpd; and
elongation at break, 12.5 to 13.2%.
In U. S. Patent No. 3,946,100, flbers are spun from a spinneret
and solidified at a temperature below 80C. The solidified fibers are
then reheated to a temperature between the polymer's glass transition
temperature (Tg) and its melting temperature. This heated fiber is
withdrawn from the heating zone at a rate of between 1,000 to 6,000
meters per minute. Spun yarn propertles are as follows: tenacity, 3.7
to 4.0 gpds initial modulus, 70 to 76 gpd/100%s and birefriengence,
0.1188 to 0.1240.
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~ n U.S. Patent No. 4,491,657, polyester multifilament yarn is
melt-spun at high speed a~d solidlfled. Solidification occurs in a
zone comprising, in series, a heating zone and a cooling zone. The
heating zone is a barrel shaped heater (temperature ranging from the
polymer's melting temperature to 400C) ranging in length from 0.2 to
1.0 meters. The cooling zone is cooled by air at 10 to 40C. Drawn
yarn made by this process has the following properties: initial
modulus, 90 - 130 gpd: and shrinkage (at 150C) less than 8.7%.
In U. S. Patent No. 4,702,871, fiber is spun into a chamber
having a subatmospheric pressure. Spun yarn properties are as follows:
strength, 3.7 to 4.4 gpd: birefriengence, 104.4 to 125.8 (x 10 3): and
dry heat contraction, 4.2 to 5.9% at 160C Sor 15 minutes.
In U. S. Patent No. 4,869,958, the fiber is spun in the absence
of heat and then taken up. At this point, the fiber has a low degree
of crystallinity, but it is highly oriented. Thereafter, the fiber is
heat treated. The drawn fiber propertles are as follows: tenacity,
4.9 to 5.2 gpd: initial modulus, 92.5 to 96.6 gpd/100%; and
elongatlon, 28.5 to 32.5%.
The foregoing review of patents indicates that while some of the
fibers produced by these various processes have high strength or low
shrlnkage properties, none of the foregoing patents teach o~ a yarn or
a proces~ ~or producing such a drawn yarn having the combination of
high tenacity, high lnltlal modulus, and low shrinkage.
The patents which come closest to teaching such a drawn yarn are
U. S. Patent Nos. 4,101,525 and 4,195,052, related patents that are
assigned to the assignee of the instant invention. In these patents,
the polyester filaments (the polymer having an intrinsic viscosity of
0.5 to 2.0 deciliters per gram) are melt spun from a spinneret. Molten
filaments are passed through a solidification zone where they are
uniformly quenched and transformed into solid fibers. The solid
fibers are drawn from the solidification zone under a su~stantial
stress (0.015 to 0.15 gpd). These as-spun solid fibers exhibit a
relatively hlgh birefrlengence (about 9 to 70 x 10 3). The a~-spun
flbers are khen drawn and subsequently heat treated. The drawn
filament ~roperties are as follows: tenacity, 7.5 to 10 gpd; initial
modulus, 110 to 150 gpd/100%: and shrinkage, less than 8.5% in air at
175C.
Summary of the Invention
The instant invention i9 directed to a drawn polyester yarn.
This yarn is characterized by an initial secant modulus greater than
150 grams per denier/100%. The yarn may be ~urther characterized by
either a shrinkage o~ le~s than 8% or a tenacity o~ greater than 7.5
grams per denier. Alternatlvely, the yarn is characterized by a
tenacity of at least 10 gram~ pQr denler, an lnltlal modulus of at
least 120 grams per denier/100% and a shrinkage of les6 than 8%.
DescriPtion of the Drawinq
For the purpose of illustrating the invention, there is shown in
the drawing a 6chematic of the process which is presently preferred:
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it being understood, however, that this invention is not limited to
the preci~e arrangement and instrumentalities shown.
Figure 1 is a schematic elevational view of the spinning process.
Figure 2 is a schematic elevational view of the drawing process.
Detailed Descri~tion of the Invention
High tenacity, high initial modulus, and low shrinkage drawn
yarns and the process by which such yarns are spun are discussed
hereinafter. The term "yarn" or "~llament" or "~lber" shall refer to
any fiber made from a melt spinnable synthetic organic polymer. Such
polymers may includa, but are not limited to, polyesters and
polyamides. The invention, however, has particular relevance to
polyesters such ac, for example, polyethylene terephthalate (PET),
blends of PET and polybutylene terephthalate (P~T), and PET
cross-linked with multifunctional monomers (e.g. pentaerithritol). Any
of the foregoing polymers may include conventional additives. The yarn
I.V. (~or PET based polymer) may be between 0.60 and 0.87. The instant
lnvention, however, i5 not dependent upon the intrinsic visaosity
(I.V.) o~ the polymer.
Re~errlng to Figure 1, a spinning apparatus 10 is illustrated. A
conventional extruder 12 for melting polymer chip is in fluid
communication with a conventional spinnlng beam 14. Within spinning
beam 14, there i8 a conventional spinning pack 16. Pack 16 may be of
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an annular design and it filters the polymer by passing the polymer
through a bed of finely divided particle~, as is well known in the
art. Included as part of the pacX 16 is a conventional spinneret (not
shown). Flow rates of polymers through the pack may range from about
10 to 55 pounds per hour. The upper limit of 55 pounds is defined
only by the physical dimensions of t~e pack 16 and greater flow rates
may be obtained by the use of larger pac~s. The spun denier per
filament (dpf) ranges from 3 to 20: it being found that the optimum
properties and mechanical qualities for the yarn appear between 5 and
13 dpf.
Optionally, the fiber, as it leaves the spinneret, may be
guenched with a hot inert gas (e.g. air). See U. S. Patent No.
4,378,325 which is incorporated herein by reference. Typically,
the gas i8 about 230C and i9 provided at about six standard cubic
feet per minute (scfm). If the air is too hot, i.e. over 260c, the
spun yarn properties are significantly deteriorated.
Immediately below and snugly (i.e. airtlght) mounted to spinning
beam 14 ls an elongated column 18. The column comprlses an insulated
tube havlng a length o~ about 5 meters or greater. Column length will
be discussed in greater detail below. The tube's internal dlameter ls
sufflciently large (e.g. twelve inches) so that all fllaments from the
spinneret may pa6~ the length of the tube without obstruction. The
column is equipped with a plurallty of conventlonal band heaters so
that the temperature within the tube can be controlled along its
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length. Column temperatures will be discussed ln greater detail
below. The column is, pre~erably, subdivided into a ~umber o~
discrete temperature zones for the purpose of better temperature
control. A total of 4 to 7 zones have been used. optionally, the
column 18 may include an air sparger 17 that is used to control
temperature in the column. sparger 17 is designed to evenly
dlstribute an inert gas around the circumference of the column.
Inside the bottom-most end of the column 18 is a perforated,
truncated cone 19, i.e. a means for reducing air turbulence. The cone
19, which is preferably three feet in length and havlng a dlameter
co-extensive with the tube diameter at its uppermost end and a
diameter of about one half that at the bottom end, is used to exhaust
air, via a valved exhaust port 21, from the bottom-most end of the
tube so that movement in the thread line, due to air turbulence, is
sub~tantlally reduced or ellminated co~pletsly.
3elow the bottom-most end of the column, the thread line is
converged. This convergence may be accomplished by a finish
applicator 20. This i8 the first contact che yarn encounters after
leaving the spinneret.
The length of the column, non-convergence of the individual
filaments, and the air temperature profile within the column are of
particular importance to the instant invention. With regard to the
temperature profile, it is chosen so that the fibers are maintained at
a temperature above their Tg over a significant length o~ the column
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(e.g. at least 3 meters). This temperature could be maintained over
the entire length of the column, but the wound ~ilaments would be
unstable. Therefore, for practical reasons, the temperature within
the column is reduced to below the Tg, so that the filaments will
undergo no further changes in crystal structure before being wound up.
Preferably, the temperature profile is chosen to reflect the
temperature profile that would be established within the tube if no
external heat was applied. However, the "no external heat" situation
is impractical because of numerous variables that influence the column
temperature. So, the temperature profile is controlled, preferably in
a linear fashion, to eliminate temperature as a variable in the
proces~.
The air temperature within the column i~ controlled by the use of
the band heaters. Preferably, the column is divided into a plurality
o~ sections and the air temperature in each section ls controlled to a
predetermined value. Thus, the temperature within the column can be
varied over the length of the column. The temperature within the
column may range from as high as the polymer spinning temperature to
at or below the gla~s transitlon (Tg) temperature c~ the polymer (Tg
~or polyester ls about 80C). The polymer spinning temperature occurs
around the spinneret, i . e. as the molten polymer exits the spinneret.
However, air temperatures within the column are preferably controlled
from about 155C to about 50C. At wind-up speeds less than 14,000
feet per minute, the first section ad~acent the spinneret is
preferably controlled to a temperature o~ about 155C and the section
furthest from the spinneret is controlled to about 50C.
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However, a linear temperature profile i5 not the only temperature
pattern that wlll yield the beneficial results disclosed herein. At
taXe-up (or wind-up) speeds greater than 14 , ooo fpm (4, 300 mpm), the
temperature profile (when the column is divlded into four discrete
zones) may be as follows: (starting from the spinneret downJ the first
zone - about 105C to about 110C; the second zone - about 110C to
about 115C; the third zone - about 125 to about 130C; and the
fourth zone - 115C to about 120C.
With regard to column length, a minimum column length of five
meters (with column temperature over the polymer's Tg for at least 3
meters) with filament convergence thereafter appears to be necessary
for the instant lnvention. Column lengths between five and nlne meters
are suitable for the inventlon. The upper limit of nine meters is a
practical limit and may be increased, room permitting. To optimize
the tenacity propQrties, a column length of about seven meters is
preferred.
The fibers are converged after exiting ths column 18. This
convergence may be accomplished by use of a finish applicator.
Following the first application of the finish (i.e. at finish
applicator 20), the yarn is taken around a pair of godet rolls 22.
Thereafter, a second application of finish may be made (i.e. at finish
applicator 23). The first finleh application may be made to reduce
statlc electricity built up on the fibers. But this finieh is
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sometimes thrown off as the fibers pass over the godet rolls~ Thus,
the finish may be reapplied after the godet rolls.
The fibers are then passed onto a conventional tension control
winder 24. The wind-up speed is typically greater than 3,000 mpm
~9,800 fpm~ with a maximum speed of 5,800 mpm (19,000 fpm). An
optimum range exists of about 10,500 to 13,500 fpm (about 3,200-4,100
mp~). The most preferred range exists between about 3200 and 3800 mpm
(10,500 and 12,500 fpmJ. At speeds below 9,800 fpm (3,000 mpm), the
yarn uniformity properties deteriorate.
The as spun polyester yarn produced by the foregoing process may
be generally characterized as having relatively small crystals and a
relatively high orientation. It is believed that these qualities of
the as spun yarn enable the attainment of the unique drawn yarn
propertie~ discussed below.
~ o quantify the general characterization of the as spun polyester
yarn, the small crystals are de~ined in terms of crystal size
(m-a~ured in ~) and orientation is de~ined in one o~ the following
terms: optlcal birefringence: amorphous bire~ringence; or crystal
blre~ringence. Additlonally, the spun polyester yarn is characterized
ln term o~ cry~tal size and long period spacing ~the distance between
crystals). In broad terms, the as spun polyester yarn may be
characterized as having a crystal size less than 55~ and either an
optlcal blrefringence greater than 0.090 or an amorphous bire~ringence
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greater than 0.060 or a long period spacing of leg8 than 300~. More
preferred, the as spun polyester yarn may be characterized as having a
crystal size ranging from about 20 to about 55~ and either an optical
birefringence ranging from about 0.090 to about 0.140 or an amorphous
birefringence ranging from about 0.060 to about O.loO or a long period
spacing ranging from about 100 to about 250~. Most preferred, the as
spun polyester yarn may be characterized as having a crystal size
ranging from about 4~ to about 54~ and either an optical birefringence
ranging from about 0.100 to about 0.130 or an amorphous birefringence
ranging from about 0.060 to about 0.085 or a long period spacing
ranging from about 140 to about 200~.
As will be apparent to those of ordinary skill in the art, the
crystal size of the spun yarn is about 1~3 that of conventional yarns
ln the optlmum wind-up speed range. The crystal size increases with
speed, but it still remains low. The spun amorphous orientation i9
very high, about twice normal. This spun yarn has such a high
orlentation and low shrinXage, that lt could be used without any
drawing.
In addltlon, the spun polyester yarn has the following
propertle6: a crvstal content (i.e. cry~tallinity level as determined
by density) o~ 10 to 43~: a ~pun tenacity of about l.i to 5.0 gpd; a
spun modulus ln the range of 10 to 140 gpd/100%: a hot air shrinkage
of about 5 to 45%; and an elongatlon of 50-160%.
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Thereaftar, the spun yarn is drawn. Refer to Figure 2. Either a
one or two stage drawing operation may be used. However, it has been
determined that a second stage offers little-to-~o additional benefit.
It is possible that the spinning operation may be coupled directly to
a drawing operation (i.e., spin/draw proces~).
The as-spun yarn may be fed from a creel 30 onto a feed roll 34
that may be heated from ambient temperatures up to about 150C.
Thereafter, the fiber is fed onto a draw roll 38 which may be heated
from ambient temperatures to approximately 255C. If heated rolls are
not available, a hot plate 36, which may be heated from 180 - 245,
may be used. The hot plate 36 (having a six inch curved contact
surface) is placed in the draw zone, i.e., between feed roll 34 and
draw roll 38. The draw speed ranges from 75 to 300 meters per minute.
The typical draw ratlo is about 1.65 (for spun yarn made at about
3,800 meters per minute). The optimum feed roll temperature, givlng
the highest tensile strsngth, was found to be about 90C. The optimum
draw roll temperature is about 245C. If the hot plate is used, the
optimum temperature is between about 240 - 245C. The draw roll
temperature gives some control over hot air shrinkage. In general,
low ~hrlnXage~ are deslrable as they give rise to the best treatéd
cord stablllty ratlngs. However, at least one end use, sail cloth,
requlres higher drawn yarn shrlnkages and these can be controlled wlth
lower draw roll temperatures.
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Based on the foregoing, the drawn fiber properties may be
controlled as follows: Tenacity may range from 4.0 to 10.8 grams per
denier. T~e elongatio~ may range from 7% to approximately 80%. The
initial secant modulus may range from 60 to 170 gpd/100%. The hot air
shrinkage (at 177C) is 6% to 15%. The denier of the fiber bundle
may range from 125 to llOo (the latter number may be obtained by
plying tows together) and the denier per filament ranges from 1.5 to 6
dpf. Such a yarn could be used as the fibrous reinforcement of a
rubber tire.
Polyester (i.e., PET) drawn yarns, made according to the process
described above, can obtain an initial secant modulus greater than 150
grams per denier/100. Moreover, those yarns may also have a shrinkage
of less than 8%, or those yarns may have a tenacity of greater than
7.5 grams per denier.
Another preferred embodiment of the drawn polyester yarn may be
characterized as follows: a tenacity of at least 8.5 grams per denier;
an lnitial modulus of at least 150 grams per denierJ100%, and a
shrlnkage of less than 6%. Another preferred embodiment of the drawn
polyester yarn may be characterized as follows: a tenacity of at least
10 grams per denier; an initial modulus of at least 120 grams per
denier/100%s and a shrinXage of less than 6%. Yet another preferred
embodiment of the drawn polyester yarn may be characterlzed as
follows: a tenacity ranging from about 9 to about 9.5 grams per
denler; an initial modulus ranging from about 150 to about 158 grams
per denier/100%s and a shrinkage les~ than 7.5%.
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Any drawn yarn, made according to the above described process,
may be utilized in the following end uses: tire cord, sewlng thread;
sail cloth; cloth, webs or mats used in road bed construction or other
geo-textile applications; industrial belts; composite materials:
architectural fabrics; reinforcement ln hoses; laminated fabrics;
ropes: etc.
The following critical tests, which are used in the foregoing
dlscusslon of the inventlon and the subsequent examples, were
performed as follows:
Tenacity refers to the "oreaking tenacity" as defined in ASTM
D-2256-80.
Initial modulus (or "lnitial secant modulus") i5 defined per ASTM
D-2256-80, Section 10.3, except that the line representing the initial
straight line portions of the stress-strain curve is specified as a
secant line passing through the 0.5% and 1.0% elongation points on the
stress-straln cur~e.
All other tensile propertles are as defined in ASTM D-2256-80.
. ShrinXage (HAS) is defined as the linear shrinkage in a hot air
environment maintained at 177+1C per ASTM D-885-85.
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Density, crystal size, long period spacing, crystal
blrefringence, and amorphous birefringence are the same as set forth
in U.S. Patent No. 4,134,882 which is incorporated herein by
reference. Specifically, each of the foregoing may be found in U.S.
Patent No. 4,134,882 at or about: density - column 8, line 60; crystal
size - column 9, line 6; long period spacing - column 7, line 62;
crystal birefringence - column 11, line 12; and amorphous
birefringence - colYmn 11, line 27.
Blrefringence (optical birefringence or ~n) is as set forth in
U.S. Patent No. 4,101,525 at column 5, lines 4-46. U.S. Patent No.
4,101,525 is incorporated herein by reference. "Bi CV" is the
coefficient of variation of optical birefringence between filaments
calculated from 10 measured filaments.
Other tests referred to herein are performed by conventional
methods.
Reference should now be made to the Examples whlch will more
rully lllu~trat- the instant lnventlon.
Example I
In the followlng set o~ experimental runs, a conventional
polyester polymer (PET, IV-0.63) was spun. The spinning speeds were
increased from 12,500 fpm to 19,000 fpm. The column length was 6.4
meters and divided into four temperature control zones. The
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temperature was controlled by measuring the air temperature close to
the wall at the center of each zone. The polymer was extruded at a
rate of 22.9 pounds per hour through a spinning beam at 285C and a 40
hole spinneret (hole size 0.009 inches by 0.013 inches). The fibers
were not quenched. The spun fibers were not drawn, but they were heat
set. The results are set forth in TA~LE I.
TABLE I
No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8B
Spin Speed, fpm 12,500 13,500 14,500 15,500 16,500 17,500 18,500 19,000
Col - ~op, 'C110 108 105 104 105 105 106 105
T~mp. 2nd, ClOS 104 104 107 109 110 106 110
3rd, C131 130 129 132 132 132 130 133
~otto~, C 109 107 105 111 111 111 109 119
Denler340 310 290 270 255 240 225 220
dpf 8.5 7.8 7.2 6.8 6.4 6.0 5.6 5.5
~True Stress"
st Bresk gpd6.51 6.41 6.55 6.65 7.23 6.98 6.86 7.14
Spun: Denier340 316 289 270 254 240 228 222
s Tensclty, gpd 3.93 3.89 4.10 4.18 4.55 4.52 4.57 4.71
Elong, ~ 65.7 64.8 59.8 59.2 59.0 54.5 50.0 51.6
Tl~ 31.8 31.3 31.7 32.3 34.9 33.4 32.3 33.8
I.M.,gpd/100~ 54 0 56.4 52.1 59.2 65.4 60.1 66.6 76.2
HAS, ~-350'F 6.0 6.5 7.0 7.5 7.2 7.5 7.0 7.2
Uster, ~.96 1.29 1.14 1.28 1.33 1.59 1.34 1.52
Finlsh, ~ .098 .358 .119 .168 .263 .037 .160 .267
IV .623 .630 ,629 .631 .630 .629 .626 .627
~ Cryst.3 34.2 35.3 37.2 39.0 40.3 42.2 43.2 43.3
Qn x 10 108 106 115 112 118 124 127 130
BlCV ~ 2 4.3 6.5 5.8 4.7 6.7 6.9 8.4
Donslty,gmJ/cc 1.3728 1.3742 1.3766 1.3788 1.3804 1.3827 1.3840 1.3841
Ylelt Polnt
Tenaclty, gpd 1.18 1.26 1.38 1.48 1.57 1.67 1.75 1.80
Heae-Set: Denler 338 308 287 271 252 240 226 231
Tenaclty, gpd 4.06 4.19 4.26 4.34 4.33 4.46 4.65 4.64
Elong, ~ 62.3 58.6 53.2 51.0 49.5 46.6 44.4 45.1
Tl ~ 32.0 32.1 31.1 31.0 30.5 30.5 31.0 31.2
I.M.,gpd/100~ 60.2 62.2 66.3 70.0 68.8 64.0 73.2 72.6
HAS, ~-350-F 2.0 2.2 2.8 2.8 3.0 3.2 3.0 2.5
Cryst.3 55.7 55.9 56.6 56.9 S6.9 57.0 57.3 57.2
~n x 10 152 142 143 145 150 146 156 160
BlCV ~ 5;8 7.9 7.9 6.3 7.0 6.5 9.1 6.3
Density,gQs/cc 1.3996 1.3999 1.4007 1.4011 1.4011 1.4013 1.4016 1.4015
Yleld Point
Tenscity, gpd 0.89 0.97 1.04 1.11 1.19 1.25 1.33 1.30
... .. . . -
20~9~5~
Example II
In the following set of experimen~al runs, a conventional
polyester (PET, IV-0.63) was spun. The column temperatures were
varied as indicated (air temperature, center of zones). The column
length was 6.4 meters. The polymer was extruded at a rate of 23.1
pounds per hour through a spinning beam at 300C and a 72 hole
spinneret (hole size o.Oo9 inches by 0.012 inches). The fibers were
not quenched. The spun fibers were subsequently drawn (as indicated).
The results are set forth in TABLE II.
2~39~5~
TABLE II
No. 1 No._4No. 5 No. 2No. 3No. 6 No. 7
Spin Speed-fpm-lOOO's 10.5 10.5 10.5 12.5 12.5 12.5 12.S
Hot Quench-scfm/C 6/230
Air Bleed*-scfm/C 30/35
Col. Temp Top C70 68 120 80 98 121 135
2nd C83 101 99 81 88 101 107
3rd C75 88 85 75 78 86 88
Bottom C 62 72 79 64 65 80 81
Spun: Denier 370 367 369 344 342 342 342
Tenacity-gpd 2.87 3.68 3.77 3.50 3.72 3.86 3.75
Elong-~ 122 81.8 83.2 82.6 79.6 70.9 69.0
I~M~-gpd/ioo% 63 93 93 86 86 73 75
HAS-~ 350F65.5 27.2 41.0 49.5 42.0 11.2 9.5
Uster-~ 1.38 1.14 1.41 '.99 1.13 1.23 2.29
Finish-~ '1.82 .44 .74 .96 .85 .50 .54
IV 3 . .63 .64 .64 .64 .64 .64 .64
~n x 10 78 11,5 113 105 111 107 106
3 Cryst~11.0 17.9 16.6 14.8 15.9 20.5 24.7
Max Draw Ratio (D.R.)1.70 1.80 1.80 1.60 1.57 1.77 1.74
Denier 224 210 213 218 227 202 206
' Tenacity-gpd5.60 8.72 8.63 7.31 7.04 8.74 8.67
elong-~ 18.4 8.9 8.6 11.0 11.6 7.5 8.1
l.M.-gpd/100~ 92 137 133 127 110 146 140
HAS~ 350-F 6.2 10.0 9.8 9.2 7.8 10.0 lO.0
M~x D.R. - .03 1.65 1.77 1.77 1.S4 1.54 1.74 1.72
Denler 230 214 217 227 231 205 205
Tenaclty-gpt5.34 8.30 8.72 7.04 7.09 8.61 8.31
Elong~ 19.9 9.3 9.2 13.1 13.1 7.7 7.6
I,M. gpt/100~ 82 120 137 123 107 145 124
HAS~ 350'F 6.0 9.8 10.0 9.0 7.8 10.2 10.0
*Alr sparger, item 17, Figure 1
In the above set of experimental runs (i.e., those set forth in
TABLE II), Nos. 4, 5, 6 and 7 represent the instant invention.
Example III
In the following sets of experimental runs, conventional
polyester (PET, IV-0.63) was spun. The fibers were wound up at a rate
- ~ .
~)3~8~
of 10,500 fpm. The polymer was extruded at a rate of 19.5 pounds per
hour through a 72 hole spinneret (hole size 0.009 inches by 0. 012
inches) and a spinning beam at 300C. The fibers were quenched with
6.5 scfm air at 232C. The column was 6.4 meters long and divided
into 4 sections having the following air temperature profile (in
descending order): 135C; 111C; 92C; and 83C at the center of the
zones. The spun yarn had the following properties: denier - 334;
tenacity - 4.09 gpd; elongation 71.7% initial modulus - 55.0
gpd/100%; hot air shrinkage - 11.8% at 350F.; Uster 1.10; I.V.
-0.647: FOY - 0. 35%, birefringence - 110 x 10 3; and cry tallinity -
21.6%.
In TABLE IIIA, the effect of draw ratio on drawn yarn properties
ig illustratQd.
TABLE IIIA
Draw_Ratlo _ _ 1.65 1.60 1.54
Den er 209 218 226
Tenacity gpd 8.15 7.53 7.12
Elongatlon % 8.4 3.9 10.4
Inltlal Modulus gpd/100O 123 115 115
Hot Alr Shrinkage % 350 F 12.0 12.4 12.0
In Table III13, the effect of the heating method during stretching
is illustrated (the draw ratio was 1.65 and the yarn was not ,relaxed).
.
20398~1
TABLE IIIB
Hot Air Feed Hot Draw
Initial Shrinkage Roll Plate Roll
Denier TenrlcitY ElonR~ion Modulus 350F Temp. TemP. Temp.
gpd ~ gpd/L00~ ~ C C C
334 4.09 71.7 55 11.8 (As Spun)
209 8.15 8.4 12312.0 Amb 245 Amb
214 6.67 9.2 95 19.0 78 Amb Amb
212 8.05 9.3 86 8.0 78 245 A~b
209 8.05 9.0 93 9.0 78 Amb 200
211 8.45 9.1 110 9.2 78 245 200
211 7.96 8.8 110 9.2 100 245 200
211 8.18 9.2 108 9.2 120 245 200
In Table IIIC, the effect of higher drawing temperatures and draw
ratios is illustrated (the feed roll is at ambient temperature and the
draw roll is at 240C).
TABLE IIIC
Draw Ratio 1.76 1.72 1.70 1.67 1.64 1.61
D~nier 195 194 199 203 209 208
Tenac~ty gpd9.50 9.22 8.89 8.73 7.76 6.71
Elongatlon ~ 6.1 6.1 6.3 6.7 6.6 7.5
Hot Alr Shrlnkago ~-350F 6.8 7.0 6.86.5 6.8 6.5
Example IV
In the following set of experimental runs, a conventional
polye~ter (PET, IV-0.92) wa~ spun. In runs Nos. 1-5, the fibers were
spun and drawn in accordance with the methods set forth in U. S.
Patent Nos. 4,101,525 and 4,195,052. NOB. 6-9 were made as follows:
PET with a molecular weight characterized by an I.V. of 0.92 was
drlod to a moi~ture level of 0.001% or less. This polymer was melted
,
~ .
203~
and heated to a temperature of 295C in an extruder and subse~uently
forwarded to a spinning pack by a metering pump. This pack was of an
annular design, and provided filtration of the polymer by passing it
through a bed of f inely divided metal particles. After f iltration the
polymer was extruded through an 80 hole spinneret. Each spinneret
hole had a round cross section with a diameter of 0.457 mm and a
capillary length of 0.610 mm.
An insulated heated tube 9 meters in length was mounted snugly
below the pack and the multifilament spinning threadline passed
through the entire length of thi~ tube before being converged or
coming into contact with any guide surfaces. The tube was divided
down its length into seven zones for the purposes of temperature
control. Individual controllers were used to set the air temperature
at the center of each of these zones. Using a combination of process
heat and the external heaters around the tube, individual controller
settlngs were selected to arrive at a uniform air temperature profile
down the vertical dlstance of this tube. In a typical situation the
air temperature was 155C at the top zone of the tube and the
temperature was reduced ln an approxlmately uniform gradie~t to 50C
at the bottom.
Approximately 10 cm below the tube the threadline was brought
into contact with a finish applicator which also served as the
convergence guide and the first contact that the yarn encountered. At
the exit of the tube the cross section o~ the un-converged yarn was
24
21~3~51
very small due to the proximity of the finish guide. This pexmitted a
very small aperture to be used, thus minimizing the amount of hot air
lost from the tube.
Following the application of spin finish the yarn was taken to a
pair of godet rolls and then to a tension controlled winder. Wind up
speeds were typically in the range 3200 - 4100 mpm.
Drawing of this yarn was effected in a second step, in which the
as spun yarn was passed over one set of pretension rolls to a heated
feed roll maintained at a temperature set between 80 and 150C. The
yarn was then drawn between these rolls and a set of draw rolls
maintained at a set point chosen in the range 180 to 255C. A typical
draw ratio for a spun yarn made at 3800 mpm would be 1.65, with
samples spun at higher and lower speeds requiring lower or higher draw
ratios, respectively.
The results are set forth in TABLE IV.
2~39~1
.
T~LE IV
Fecd Roll Ten~erature C
InitiR~ Initi6~
Ten~cityMcdulus Dr~n Y-rnTenoc~ty Modu~ Dr~n rarn
sPd ~ OOX Shrink~e % gpd ~d/100X Shr~nkl~g~ X
SpimingS~ flrn 150-F 350-F
Speed 3irefringence
~o. ~f~n) x10 3
5000 21.9 7.94 115.00 7.30 5.9~ ~8,00 5.30
26000 30.1 7.85 118.W 7.00 6.90 103.00 6.70
3 7W0 45.2 3.3S 120.00 7.00 7.21 108.00 6.50
-4 ôO00 60.5 ~.51 130.00 7.80 7.31 113.00 6.00
59000 7~ 8.56 122.00 6.80 7.67 110.00 6.00
610500 104 9.52 158.00 7.50 10.94173.00 7.30
711500 115 9.03 150.00 6.80 9.52 152.00 7.00
812500 121 9.08 152.00 7.50 9.53 160.00 7.30
913500 119 9.32 15~.00 6.00 9.58 161.00 ~.?0
EXAMPLE V
Polyester with a molecular weight characterized by an I.V. of
0.92 was dried to a moisture level of 0.001%. This polymer was melted
and heated to a temperature of 295C ln an extruder and the melt
subsequently forwarded to a spinning pack by a metering pump. After
filtration in a bed of finely divided metal particles, the polymer was
oxtrudod through an 80 hole spinneret. ~ach spinneret hole had a
dia~-ter of 0.457 mm and a capillary length o~ 0.610 mm. on extrusion
the measurQd I.V. of this polymer was 0.84.
, The extruded polymer was spun into heated cylindrical cavity 9
meters in length. An approximately linear temperature profile
~gradient) was maintained over the length of thls tube. At the center
of the top zone the air temperature was 155C and at the bottom of the
26
....
2 ~ 3 ~
tube this temperature was 50C. The multifilament yarn bundle was not
converged until it came in contact with a finish guide just below the
exit of the heated tube. From this point the yarn was advanced by a
pair of godet rolls to a tension controlled winder. Und~r these
conditions a series of four spun yarns were made at dif~erent splnning
(wind-up) speeds. These yarns are referred to as examples A through D
in Table V. A.
In another series of experiments the heated tube was shortened by
taking out some of its removable sections. Examples E and F in Table
V. A were spun through 7 and 5 meter columns. Other polymers with
different molecular weights (I.V.'s) were also spun on this system to
give Examples G and H. Example I in Table VA illustrates a case in
which lower column temperatures were used. In this case a linear
gradient from 125C to 50C was established down the column.
All spun yarns in the series A through I were drawn in a single
stage proCess using an ambient feed roll and a 245C draw roll.
In a rurther serles of tests the same spun yarn which was
described in Example A was drawn using different feed roll
temperatures. The results from testing these yarns are given in
Examples A, J and K in Table V. 3.
2~3~
TABLE V. A
S~innin~ Conds
Spin Temp Spun Spun Yarn Draw Drawn Yarn
Exa~ple LenRth Speed C _V Bir Cryst Ratio Ten I.M. HAS
mpm ~ gpd gpd/100~ ~-350F
A 9 3200 155 0.84 .104 30.5 1.89 9.52 158 7.s
B 9 3500 155 0.84 .115 34~4 1.79 9.03 150 6.8
C 9 3800 155 0.84 .121 35.9 1.74 9.08 152 7.5
D 9 4100 155 0.84 .119 38.9 1.72 9.32 154 6.0
E 7 3200 155 0.84 .101 30.1 1.79 8.99 142 7.3
F 5 3200 155 0.84 .073 25.0 1.98 9.52 159 7.0
G 9 3200 155 0.76 .110 34.0 1.65 8.63 123 6.0
H 9 3200 155 0.66 .102 22.9 1.57 7.25 110 5.0
I 9 4100 125 0.84 .120 31.9 1.53 7.34 116 5.3
TABLE V. ~ -
Feed Roll Draw Drawn Drawn Hot Air
ExampleTemp C RatioTenacityI Modulus Shrink
gpd gpd/100% ~-350F
A 25 1.89 9.52 158 7.5
J 90 1.82 10.94 173 7.7
K 150 1.87 10.30 158 7.4
EXUiMPLE VI
In the ~ollowing experimental run, a conventional polymer, nylon,
was spun accordlng to the inventive process and compared to nylon made
by conventlonal processes.
The nylon made by the inventive process was spun under the
~ollowing conditions: throughput- 37 lbs. per hour; spinning speed -
2,362 fpm; denier - 3500; number of filaments - 68; spun relative
viscosity - 3.21 (H2 S04) or 68.4 ~HCOOH equiv.) quench air - 72 scfm;
winding tension 80g; column length - 24 ~t; column temperature top
240C and bottom 48C. The as-spun properties o~ thls yarn were as
28
.
2 [139~
follows: tenacity - 0.95 gpd; elongation 235% TEl/2 - 14.6.
Thereafter the yarn was drawn under the following conditions: draw
ratio 3.03; draw temperature 90C. The drawn yarn properties are as
follows: tenacity 6.2 gpd: elongation -70%: TEl/2 - 52: 10% modulus -
0.87 gpd; hot air shrinkage (HAS) at 400F - 1.4%.
One comparative nylon was spun in the following conventional
fashion: throughput - 23.4 lbs. per hour, spinning speed - 843 fpm:
denier - 5556; number of filaments - 180; spun relative viscosity -
3.3 (H2 S04) or 72.1 (HCOOH equiv.): quench - 150 scfm. Thereafter,
the yarn was drawn under the following conditions: Draw ratio - 2.01;
draw temperature - 90C. The drawn yarn properties are as follows:
tenacity 3.8 gpd: elongation - 89%: TEl/2 - 33; 10% modulus - .55 gpd.
Another comparative yarn was spun in the following conventional
~ashion: throughput - 57.5 lbs. per hour; spinning speed - 1048 fpm;
denier - 12400; number of filaments - 240; spun relative viscosity -
42 (HCOOH equlv.); quench air - 150 scfm. Thereafter, the yarn was
drawn under the following conditions: draw ratio - 3.60; draw
tamperature - 110C. The drawn yarn properties ar~ as follows:
tenacity - 3.6 gpd; elongation - 70%; TEl/2 - 30.1~ modulus at 10%
elongation - 0.8 gpd; HAS (at 400F) - 2.0%.
EXAMPLE VII
In the followlng experimental runs, low I.V. (e.g. 0.63) and high
I.V. ~e.g. 0.92) conventlonal polyester (i.e. PET) as gpun yarn is
compared with as spun yarn set ~orth in U.S. Patent No. 4,134,8~2.
29
2~3~
Examples 1-8 are low I.V. polyester (PET~ and are made in the manner
set forth in Exa~ple I. Examples 9-ll are high I.V. polyester (PET)
and are made in the manner set forth in Example V. Examples 12-17
correspond to Examples l, 5, 12, 17, 36 and 20 of U.S. Patent No.
4~134~8a2.
For each example, the spinning speed (fpm), density (gms/cc),
crystal size (~, OlO), long period spacing (LPS), birefringence
(biref.), crystal birefringence and amorphous birefringence are given.
The results are set forth in Table VII.
TABLE VII
Spin CS LPS
Speed Density 0~0 0 Crystal Amorphous
No. (fpm) ~ms/cc A A Biref.Biref. Biref.
1 12500 1.3728 45 147 0.10800.1982 0.067
2 13500 1.3742 45 160 0.10600.1994 0.061
3 14500 1.3766 47 155 0.11500.2004 0.070
4 15500 1.3788 50 158 0.11200.2021 0.060
16500 1.3804 51 145 0.11800.2035 0 066
6 17500 1.3827 53 152 0.12400.2042 0 071
~ 18500 1.3840 55 147 0.12700.2055 0.073
8 19000 1.3841 54 150 0.13000.2052 0.078
9 10000 1.3485 21 192 0.07610.1824 0.063
10000 1.3653 43 192 0.10470.1930 0.075
11 12500 1.3749 52 183 0.12150.1994 0.083
12 16500 1.3700 61 313 0.09580.2010 0 045
13 1800G 1.3770 73 329 0.10820.2010 0 057
14 19500 1.3887 72 325 0.11530.2030 0.054
lS 21000 1.3868 68 330 0.12410.2050 0.063
16 21000 1.3835 64 0.12360.1980 0.073
17 16500 1.3766 65 0.09650.2060 0.038
The present invention may be embodied in other specific forms
without departing from the spirit or essential attributes thereof and,
accordlngly, re~erence should be made to the appended claims, rather
than to the ~oregoing speci~ication, as indicating ths scope of the
invention.
