CA2040093A1 - As-spun polyester yarn having small crystals and a high orientation - Google Patents

Abstract

ABSTRACT OF THE INVENTION

AN AS-SPUN POLYESTER YARN HAVING
SMALL CRYSTALS AND A HIGH ORIENTATION

The instant invention is directed to as-spun polyester yarn having small crystals and a high orientation. The as spun polyester yarn is characterized by a crystal size less than 55.ANG. and either an optical birefringence greater than 0.090 or an amorphous birefringence greater than 0.060 or a long period spacing less than 300.ANG..

Description

2 ~ 9 3 AN AS-SPUN POLYESTER YARN HAVING
SMALL CRYSTALS AND A HIGH ORIENTATION

Field of the Invention The instant invention is directed to an as-spun polyester yarn having small crystals and a high orientation.

Backqround o~ the Invention Since fiber-forming, melt-spinnable, synthetic polymers were introduced, fiber manufacturers have looked for ways to increase the strength and stability properties of the fibers made from those polymers. The addltional strength and stabllity properties o~ the ~ibers are needed so that applications beyond textile uses could be opened for their products. Such non-textile uses (also known as "industrial uses") include: tlre cord; sewing threadJ sail cloth;
cloth, webs or mats used ~or road bed construction or other geo-textlle applicationss industrial beltq~ composite materlals;
architectural fabrlcss reinforcement in hoses; laminated ~abrics;
ropes; and the llXe.

Originally, rayon was used in some of these industrial uses.
Thereafter, nylon supplanted rayon as the material of choice. In the 1970IB, conventional polyesters, such as polyethylene terephthalate, were introduced into competitlon against nylon. In about 1985, higher perfor~ance polyesters, i.e. higher strength and greater stability, were introduced.

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A brie~ review o~ some of the patent prior art, summarized below, indicates that three general areas 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 processe~
directed to the spinning. Hereinafter, the term "drawinq" shall refer to the heating and stretchlng performed on an as-spun yarn. The term "treatment to the polymer" shall refer to those thin~s done to the polymer prior to spinning. The term "spinning" shall refer to processes for forming filaments from polymer, but excluding drawing.

The processes directed to drawing are as follows:

In U. S. Patent No. 3,090,997, multistage drawing of polyamides, ror ugQ as tire cords, i8 dlsclosed. The fibers (nylon) are melt-spun in a conventional fashion. Therea~ter, qpun flbers are drawn in a three-stage process (drawn, then heated, then drawn agaln) to obtaln a drawn nylon having the ~ollowlng properties: tenacity ranging from 10.4 to 11.1 gram~ per denier (gpd); elongation ranglng from 12.9 to 17.1%; and initial modulus o~ 48 to 71 gpd/100%.

In U. S. Patent No. 3,303,169, there is disclosed a single-stage drawing process ~or polyamldes that yields high modulus, high tenacity, and low shrinkage polyamide yarns. The spun polyamide is drawn and heated to at least 115C to obtain a yarn having: tenacity in the range o~ 5 to 8.7 gpd; elongation ranging ~rom 16.2 to 30.3%;

2 ~ 3 . . .... .

initial modulus of 28 to ssgpd/100%; and shrinkage ranging from 3.5 to 15%.

In U. S. Patent No. 3,966,867, a two-stage drawing process ~or polyethylene terephthalate having a relative viscosity o~ 1.5 to l 7 is disclosed. In the first stage, the fibers are subjected 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, Ln the range o~ 5.6 to 6.1. The drawn 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 15S; and shrinkage, l to 4%.

In U. S. Patent No. 4,003,974j polyethylene terephthalate spun yarn, havlng an HRV o~ 24 to 28, is heated to 75 to 250C while belng drawn, is then pas~ed over a heated draw roll, and ~lnally relaxed.
~he drawn yarn has the ~ollowing properties: tenaclty, 7.5 to 9 gpd;
shrlnkage, about 4%; elongatlon at break, 12 to 20%: and load bearlng capaclty o~ 3 to 5 gpd at 7% elongation.

Those processe~ directed to enhanclng yarn properties by treat~ent to the poly~er are as ~ollows:

ln U. S. Patent Nos. 4,690,866 and 4,867,963, the intrinslc vl~¢oslty ~I.V.) Or the polyethylene terephthalate ls greater than - ` 2 ~
.

0.90. In U. S. Patent No. 4,690,868, the as-spun (undrawn) fiber properties are as follows: elongation at break, 52 to 193%;
birefriengence, 0.0626 to 0.136; and degree of crystallinity, 19.3 to 36.8%. The drawn fiber propertles 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 flber propertles are follows: tenacity, about 8.5 gpd;
elongation at brea~, about 9.9%: and ~hrinkage (at 177C), about 5.7%.

Those processes directed to spinning are as follows:

In U. S Patent No. 3,053,611, polyethylene terephthalate after leavlng the splnneret ls heated to 220C ln a spinning sha~t two meter~ long. Therearter, cold water i9 sprayed onto the ~ibers ln a ~econd ~haft. The flbers are taken up at a speed of 1,600 meters per mlnute ~mpm) and are sub~equently drawn to obtaln a tenaclty o~ 3.5 gpd.

In U. S. Patent No. 3,291,880, a polyamlde ls spun from a spinneret and then cooled to about 15C, then the ~lber is sprayed wlth llve ~team. The a~-spun ~lber has a low orlentatlon and a low blre~riengence.

In U. S. Patent No. 3,361,859, a synthetlc organic polymer is spun into a flber. As the ~lbers exlt the splnneret, they are ~ J~

sub~ected to "controlled retarded cooling". This cooling i9 conducted over the first seven inches from the spinneret. At the top (i.e. ad~acent the spinneret), the temperature is 300C and at the bottom (i.e. approximately 7 inches from the spinneret), tha minimum temperature ls 132C. The as-spun yarn has a low birefriengence (11 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 9.9%.

In U. S. Patent Nos. 3,936,253 and 3,969,462, there is disclosed the use o~ a heated shroud (ranging in len~th ~rom one-hal~ foot to two ~eet) with temperatures ranging from about 115 to 460C. In the ~ormer, the temperature is greater at the top of the shroud than at the bottom. The drawn yarn propertles of the ~ormer are as follows:
tenaclty, 9.25 gpd~ elongation, about 13.5%; and shrinkage, about 9.5%. In the latter, the temperature i9 constant within the shroud and the drawn yarn properties are as rollows: tenacity, 8 to 11 gpd; and elongation at break~ 12.5 to 13.2%.

In U. S. Patent No. 3,946,100, ~ibers are spun ~rom a splnneret and solidl~ied at a temperature below 80C. The solidified fibers are the~ reheated to a temperature between the polymer's glass transition temperature (Tg) and lts meltlng temperature. This heated ~iber ls withdrawn ~rom the heatlng zone at a rate o~ between 1,000 to 6,000 meters per minute. Spun yarn properties are as ~ollows: tenacity, 3.7 to 4.0 gpd; initial ~odulus, 70 to 76 gpd/100%; and blre~riengence, 0.1188 to 0.1240.

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In U.S. Patent No. 4,491,657, polyester multifilament yarn is melt-spun at high speed and solidified. 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, so - 130 gpd; and shrinkage (at 150C) less than 8.7S.

In U. S. Patent No. 4,702,871, ~iber is spun into a chamber having a subatmospheric pressure. Spun yarn properties are as follows:
strength, 3.7 to 4.4 gpd; blrefriengence, 104.4 to 125.8 (x 10 3); and dry heat contraction, 4.2 to 5.9% at 160C for 15 minutes.

In U. S. Patent No. 4,869,958, the ~iber is spun ln the absence Or heat and then taken up. At thls polnt, the ~lber has a low degree o~ crystalllnity, but lt ls hlghly orlented. Therea~ter, the ~lber is heat treated. The drawn ~iber properties are as ~ollows: tenaclty, 4.9 to S.2 gpds lnltial moduius, 92.5 to 96.6 gpd/lOOS; and elongatlon, 28.5 to 32.5S.

The roregolng revlew o~ patentq indicates that whlle some of the ~ibers produced by these varlous processes have hlgh strength or low shrlnkage proportles, none o~ the ~oregolng patents teach o~ a yarn or a process ~or producing such a drawn yarn havlng the combination o~

hlgh tenaclty, hlgh initial modulus, and low shrlnkage.

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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 instan~ invention. In these paten~s, 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 substantial stress (0.015 to 0.15 gpd). These as-spun solid fibers exhibit a relatively high ~irefriengence (about 9 to 70 x 10 3). The as-spun ~ibers are then drawn and subsequently heat treated. The drawn ~ilament properties are as follows: tenacity, 7.5 to 10 gpd; initial modulus, 110 to 150 gpd/100%; and shrinkage, le~s than ~.5% in air at 175C.

Summary o~ the Inventlon The instant invention is dlrected to as-spun polyester yarn h~vlng 9m~1l ary9tal~ ~nd ~ hlgh orientatlon. The as spun polyester yarn ls ch~racterized by a crystal slze less than 55A and either an aptical blre~ringence greater than 0.090 or an amorphous blre~ringence greater than 0.060 or a long perlod spacing less than 300A.

Descriptlon o~ the Drawina For the purpose o~ lllustrating the lnventlon, there ls shown in the drawing a schematlc o~ the process which is presently pre~erred;

it being understood, however, that this invention i5 not limited to the precise arrangement and instrumentallties shown.

~ B 4 ~ 3 Figure 1 is a schematic elevational view of the spinning process.

Figure 2 is a schematic elevational view of the drawing process.

Detailed Description of the Invention High tenacity, high initial modulus, and low shrinkage drawn yarns, the a~-spun yarn from which such drawn yarn i9 made, and the process by which such yarns arQ spun are dlscussed hereinafter. The term "yarn" or "rilament" or "~iber" shall refer to any fiber made ~rom a melt spinnable synthetic organic polymer. Such polymers may include, but are not limited to, polyesters and polyamides. The invention, however, has particular relevance to polyesters such as, ~or example, polyethylene terephthalate (PET), blends o~ PET and polybutylene terephthalate (PBT), and PET cross-linked with multl~unctlonal monomers (e.g. pentaerithritol). Any o~ the ~oregoing polymers may include conventlonal additives. The yarn I.V. (~or PET
based polymer) may be between 0.60 and 0.87. The instant invention, however, ls not dependent upon the lntrinsic viscosity (I.V.) o~ the polymer.

Re~erring to Figure 1, a spinning apparatus 10 is illustrated. A
conventional extruder 12 ~or melting polymer chip is in ~luid communication with a conventional spinning beam 14. Wlthln spinnlng beam 14, there is a conventlonal spinning pack 16. Pack 16 may be o~
an annular design and it ~ilters the polymer by pa~sing the polymer through a bed o~ ~inely divlded partlcles, as ls well known ln the art. Included as part o~ the pack 16 is a conventlonal spinneret (not 2 ~ 3 .. .... ....

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 de~ined only by the physical dlmensions of the pack 16 and greater flow rates may be obtained by the use of larger packs. The spun denier per ~ilament (dp~) ranges from 3 to 20; it being found that the optimum properties and mechanical qualities for the yarn appear between 5 and 13 dp~.

Optionally, the ~iber, as it leaves the spinneret, may be quenched 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 is about 230C and is provided at about six standard cubic ~eet per minute ~scfm). I~ the air is too hot, i.e. over 260C, the spun yarn properties are slgni~lcantly deteriorated.

Tmmediately below and snugly (l.e. alrtlght) mounted to spinnlng bean 14 19 an elongated column 18. The column comprises an insulated tube h~vlng a length o~ about 5 meters or greater. Column length will ~o diJcus~od in greater detail below. The tube's internal diameter is su~lclently large (e.g. twelve lnches) so that all ~llaments ~rom the splnnerQt may pas~ the length o~ the tube wlthout obstructlon. The column ls equlpped wlth a plurallty o~ conventlonal band heaters so that the temperature within the tube can be controlled along its length. Column temperatures will be discussèd in greater detall below. The column is, pre~erably, subdlvided lnto a number o~

discrete temperature zone~ ~or the purpose o~ better temperature ', control. A total of 4 to 7 zones have been used. optionally, the column 18 m~y lnclude an ~ir spArger 17 that 19 u~ed to control temperature in the column. sparger 17 is designed to evenly distribute an inert gas around the circumference of the column.

Inside the bottom-most end of the column 18 is a perforated, truncated cone l9, i.e. a mean~ ~or reducing air turbulence. The cone ls, which is pre erably three ~eet ln length and having a diameter co-extensive wlth the tube dlameter at it~ uppermost end and a diameter o~ about one hal~ 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 substantlally reduced or eliminated completely.

Below the bottom-most end o~ the column, the thread line ls convsrged. Thls convergence may be accomplished by a ~inlsh appllcator 20. Thls is the rlrst contac~ the yarn encounter~ a~ter le~vlng the ~plnneret.

The length Or the column, non-convergence ot the indlvidual ~llaments, and the alr temperature pro~ile within the column are o~
partlcular importance to the lnstant inventlon. With regard to the temperature pro~lle, it ls chosen so that the ~ibers are malntalned at a temperature above thelr Tg over a signl~icant length o~ the column (e.g. at least 3 meters). This temperature could be maintalned over the entire length o~ the column, but the wound ~ilaments would be unstable. There~ore, ~or 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 applled. However, the "no external heat" situation is impractical because of numerous variables that influence the column temperature, So, the temperature pro~ile is controlled, pre~erably in a linear fashion, to eliminate temperature as a variable in the process.

The air temperature within the column ia controlled by the use of the band heaters. Pre~erably, the column i8 divlded lnto a plurallty o~ sectlon~ and the air temperature in each sectlon i9 controllad to a predetermlned value. Thus, the temperature wlthin the column can be varied over the length o~ the column. The temperature within the column may range ~rom as hlgh as the polymer spinning temperature to at or below the glass transition (Tg) temperature o~ the polymer (Tg ~or polyester 18 about 80C). The polymer spinning temperature occurs around the splnneret, i.e. as the molten polymer exita the spinneret.
~OWèVQr~ alr temperature~ wlthln tne column are pre~erably controlled ~rom about 155C to about 50C. At wind-up speeds less than 14,000 ~eet per mlnuts, the ~lrst sectlon ad~acent the spinneret is pre~erably controlled to a temperature o~ about 155C and the sectlon ~urthest ~rom the splnneret i9 controlled to about 50C.

However, a linear temperature pro~ile is not the only temperature pattern that will yield the bene~lclal results disclosed herein. At taka-up (or wind-up) speeds greater than 14,000 fpm (4,300 mpm), the temperature profile (when the column is divided into ~our discrete zones) may be as follows: (starting from the spinneret down) 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 o~ five meters (with column temperature ovér the polymer's Tg ~or at least 3 meters) with ~ilament convergence thereafter appears to be necessary ~or the instant invention. Column lengths between five and nine meters are suitable for th~ inventlon. The upper limit of nine meters is a practical llmlt and may be increased, room permittlng. -To optlmize the tenaclty propertles, a column length o~ about seven meters is pre~erred.

The ~ibers are converged a~ter exiting the column 18. This convergenCe may b~ accomplished by use of a ~inish appllcator.

Followlng thQ ~lrot appllcation o~ thQ ~inish (l.e. at ~lnish applicator 20), the yarn ls taken around a pair o~ godet rolls 22~
Therea~ter, a second applicatlon o~ ~inish may be made (l.e. at ~inlsh appllcator 23). The ~lrst ~inish application may be made to reduce static electriclty bullt up on the ~ibers. But thls ~inlsh is sométimes thrown o~ as the fibers pass over the godet rolls. ~hus, the ~inish may be reapplied a~ter the godet rolls.

The fiber~ 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 optlmum range exists of about 10,500 to 13,500 fpm (about 3,200-4,100 mpm~. The most preferred range exists between about 3200 and 3BoO mpm (10,500 and 12,500 fpm). 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 unigue drawn yarn properties discussed below.

To guantify the general characterization o~ the as spun polyester yarn, the ~mall crystals are deflned in terms of crystal size (~easured in ~) and orlentatlon is defined in one of the following terms: optlcal birefringence; amorphous bire~ringence; or cry~tal birefringence. Additionally, the spun polyecter yarn is characterized in term o~ crystal size and long period spacing (t~le distance between crystals). In broad terms, the as spun polyester yarn may be characterlzed as having a cry6tal size less than 55~ and either an optical birefrlngence greater than 0.090 or an amorphous birefringence greater than 0.060 or a long perlod spacing o~ less than 300~. More pre~erred, the as spun polyester yarn may be characterized as having a crystal slze ranglng ~rom about 20 to about 55~ and elther an optical birefringence ranging from about o.o~o to about 0.140 or an amorphous birefrlngence ranglng from about o. 060 to about O.loo or a long period spacing ranging frol~ about loO to about 250~. Most pre~erred, L3~,.
~pun polyester yarn may be characterized as having a crystal size ranging from about 43 to about 54~ and either an optical birefringen,~
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 ~rom about 140 to about 200~.

As will be apparent to those o~ ordinary skill in the art, the crystal size o~ 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. Tha spun amorphous orientatlon ls v-ry hlgh, about twlce normal. This spun yarn has ~uch a high orl-ntatlon and low shrinkage, that it could be used without any drawlng.

In addltlon, the spun polyester yarn has the ~ollowing propertles: a cry~tal content (l.e. crystalllnlty level as determined by den~lty) o~ 10 to 43~; a spun tenaclty o~ about 1.7 to 5.0 gpd; a spun modulus in the range o~ 10 to 140 gpd/100%~ a hot air ~hrinkage o~ about 5 to 45%; and an elongation o~ 50-160%.

Therea~ter, the spun yarn is drawn. Re~er to Flgure 2. Either a one or two stage drawing operation may be used. However, lt has been determined that a second ~tage o~ers llttle-to-no addltional bene~lt.

It is possible that the spinning operation may he coupled directly to a drawing operation (i.e., spin/draw process).

The as-spun yarn may be fed rrOm 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. I~ heated rolls are not available, a hot plate 36, which may be heated fram 180 - 245, may be used. The hot plate ~6 (having a 5iX inch curved contact sur~ace) is placed in the draw zone, i.e., between ~eed roll 34 and draw roll 38. The draw speed ranges from 75 to 300 meters per minute.
The typical draw ratio is about 1.65 (for spun yarn made at about 3,800 meters per minute). The optimum ~eed roll temperature, giving the highest tensile strength, was ~ound to be about 90C. The optimum draw roll temperature i9 about 245C. I~ the hot plate i9 used, the optimum temperature is between about 240 - 245C. The draw roll temperature gives ~ome control over hot air shrinkage. In general, low qhrinkages are deslrable as they give rise to the best treated cord stability ratings. However, at least one end use, sail cloth, requlres higher drawn yarn shrlnkages and these can be controlled with lower draw roll temperatures.

Ba~ed on the ~oregolng, the drawn ~lber propertles may be controlled as ~ollows: Tenaclty may range ~rom 4.0 to 10.8 grams per denler. The elongatlon may range ~rom 7% to approxlmately 80%. The lnitlal secant modulus may range ~rom 60 to 170 gpd/lO0~. The hot air shrinkage (at 177C) is 6~ tc 15%. The denier of the flber bundle may range ~rom 125 to 1100 (th~ ter num~er may b~ ahtained ~y plying tows togethex) and the ~enier per filament ranges from 1. 5 to 6 dpf. Such a yarn could be ~S~ as the f~brous reinforcement of a rubber tire.

Polyester (l.e., PET) drawn yarns, made according to the proce~s described above, can obtain an initial secant modulus greater than 15u grams per denier/100. Moreover, those yarns may also have a shrinkaga o~ le~ than 8%, or those yarns may ha~e a tenacity o~ greater than 7.5 grams per denier.

Another preferred embodiment o~ the drawn polyester yarn may be characterized as ~ollows: a tenacity of at least 8.5 grams per denier;
an inltlal modulus o~ at least 150 grams per denier/100%, and a shrlnkage o~ less than 6%. Another preferred embodiment of the drawn polyester yarn may be characterized as ~ollows: a tenaclty o~ at least 10 grams per denler; an lnltlal modulus o~ at least 120 grams per denler/100%~ and a shrlnkage o~ les~ than 6%. Yet another pre~erred embodlment o~ the drawn polyester yarn may be characterized as ~OllOWB: a tenacity ranglng ~rom about 9 to about 9.5 grams per denler; an lnitlal modulus ranging ~rom about 150 to about 158 grams per denier/lOOSJ and a shrinkage less than 7.5S.

Any drawn yarn, made accordlng to the above descrlbed process, may be utlllzed ln the ~ollowlng end uses: tlre cord, sewing thread;

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sail cloth; cloth, webs or mats used in road bed construction or other geo-textile appllcation~; industrlal belts; composite materials;
architectural fabrics; reinforcement in hoses; laminated ~abrics;
ropes; etc.

The ~ollowing critical tests, which are usQd ln the ~oregoing dlscussion of the invention and the subsequent examples, were performed as follows:

Tenaclty re~ers to the "breaking tenacity" as de~ined in ASTM
D-2256-80.

Initial modulus (or "initi21 secant modulus") is de~ined per ASTM
D-2256-80, Section 10.3, except that the line representing the initial ~tralght llne portlons o~ the stress-strain curve is cpecirled as a ~ecant llne passlng through the 0.5% and 1.0% elongation points on the stress-straln curve.

All other tensile properties are as de~ined in ASTM D-2256-80.

Shrinkage (HAS) is de~lned as the llnear shrlnkage in a hot air environment maintalned at 177+1C per ASTM D-885-85.

Denslty, crystal slze, long perlod spaclng, crystal blre~ringence, and amorphous blre~ringence are the same as set ~orth in U.S. Patent No. 4,134,882 which 1~ incorporated herein by 2 ~ 3 ..... ... . ..................... ..........

re~erence. Speci~ically, 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 birefrlngence - column 11, llne 27.

3irefrlngence (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 i8 incorporated herein by reference. "Bi CV" is the coe~icient o~ varlation o~ optical birefrlngence between ~ilaments calculated ~rom 10 measured filaments.

Other tests referred to herein are performed by conventional methods.

Re~erence ~hould now bs made to the Examples whlch wlll more ~ully illustrate the lnstant invention.

Exampl~ I
In the ~ollowing set o~ experimental runs, a conventlonal polyester polymer (PET, IV-0.63) was ~pun. The splnning speeds were increased ~rom 12,500 ~pm to 19,000 fpm. The column length was 6.4 meters and dlvlded into ~our temperature control zones. The temperature was controlled by measurlng the alr temperature close to the wall at the center o~ each zone. The polymer was extruded at a rate o~ 22.9 pounds per hour through a spinning beam at 285C and a 40 hole splnneret (hole size 0.009 inches by 0.013 inches). The ~ibers 2 ~ 3 were not ~uenched. The spun fibers were not drawn, but they were hea~
set. The results are set forth ln TABLE 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 le,500 19,000 Col - Top, ~C 110 108 105 104 105 105 106 105 Temp. 2nd, ~C 105 104 104 107 109 110 106 110 3rd, C 131 130 129 132 132 132 130 133 Bottom, C 109 107 - 105 111 111 111 109 119 Denier 340 310 290 270 255 240 225 220 . dpf 8.5 7.8 7.2 6.8 6.4 6.0 5.6 5.5 "True Stress"
at Break gpd 6.51 6.41 6.55 6.65 7.23 6.98 6.86 7.14 Spun: Denier 340 316 289 270 254 240 228 222 T~nacity, gpd 3.93 3.89 4.10 4.18 4.55 4.52 4.57 4.71 Elon~, ~ 65.7 64.8 59.8 59.2 59.0 54.5 50.0 51.6 Tf~ 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 Flnlsh, ~ .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 ~n x 10 108 106 115 112 118 124 127 130 ~lCV ~ 3.2 4.3 6.5 5.8 4.7 6.7 6.9 8.4 Donslty,gm0/cc 1.3728 1.3742 1.3766 1.3788 1.3804 1.3827 1.3840 1.3841 YLeld Polnt Tenaclty, gpd l.lB 1.26 1.38 1.48 1.57 1.67 1.75 1.80 Heat-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 El~ 62.3 58.6 53.2 51.0 49.5 46.6 44.4 45.1 T~ 32.0 32.1 31.1 31.0 30.5 30.5 31.0 31.2 I.~.,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 Cry~t.3 55.7 55.9 56.6 56.9 56.9 57.0 57.3 57.2 ~n x 10 152 142 143 145 150 146 156 160 BlCY ~ 5.B 7.9 7.9 6.3 7.0 6.S 9.1 6.3 Denslty,~ms/cc 1.3996 1.3999 1.4007 1.4011 1.4011 1.4013 1.4016 1.4015 Yleld Polnt Tenaclty, gpd 0.89 0.97 1.04 1.11 1.19 1.25 1.33 1.30 Exa~ple II
In the ~ollowing set o~ experimental runs, a conventlonal polye~ter (PET, IV-0.63) was spun. The column temperatures ~ere 2 ~ 3 varied as indicated (air temperature, center of zones). The column length was 6~4 meters. The polymer was extruded at a ratQ of 23.1 pounds per hour through a spinning beam at 300C and a 72 hole spinneret (hole size 0.009 inches by 0.012 inches). The fibers were not quenched. The spun fibers were subse~uently drawn (as indicated).
The results are set forth in TABLE II.
TABLE II
No. 1 No. 4No. 5 No. 2 No. 3No. 6No. 7 _ Spin Speed-fpm-lOOO's 10.5 10.5 10.5 12.5 12.5 12.5 12.5 Hoc Quench-scfm/-C 6/230-Alr 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 Botto~ C 62 72 79 64 65 80 81 Spun: Denier 370 367 369 344 342 342 342 Tenaclty-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/lOOi 63 93 93 86 86 73 75 HAS~a 350-F 65.5 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 Flnish-~ 1.82 .44 .74 .96 .85 .50 ,54 IV 3 .63 .64 .64 .64 .64 .64 .64 ~n x 10 78 115 113 105 111 107 106 Cryst.11.0 17.9 16.6 14.8 15.9 20.5 24.7 Max Draw Ratlo tD.R.)1.70 1.80 1.80 1.60 1.57 1.77 1.74 Denler 224 210 213 218 227 202 206 Tenacity-gpt5.60 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 I.M.-gpd/100~ 92 137 133 127 110 146 140 HAS-4 350-F 6.2 10.0 9.8 9.2 7.8 10.0 10.0 Max D.R. - .03 1.65 1.77 1.77 1.54 1.54 1.74 1.72 Denler 230 214 217 227 231 205 205 Tenaclty-gpd5.34 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.-gpd/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, Flgure 1 . .... . .. . ....

In the above set of experimental runs (i.e., those set forth in TABLE II~, Nos. 4, 5, 6 and ? r~present the instant invention.

Exan,ple III
In the followlng sets of expe~ ntal runs, conventional polyester ~PET, IV-0.63) was spun. The fiber~ were wound up at a ~.~tc o~ 10,500 ~pm. The polymer was extruded at a rate of 19.5 pounds ~L
hour through a 72 hole spinneret (hole size 0.009 inches by 0.012 inches) and a spinnlng beam at 300C. The fibers were quenched wlth 6.5 scfm air at 232C. The column was 6.4 meter~ long and divided into 4 saction~ having the ~ollowing air temperature pro~lle (in descendlng order): 135C; 111C; 92C; and 83C at the center of the zones. The spun yarn had the ~ollowing propertles: denier - 334;
tenacity - 4.09 gpd; elongation 71.7%; initial modulus - 55.0 gpd/lOO~t hot air shrinkage ~ at 350F.; Uster 1.10; I.V.
-0.647J ~OY - 0.35~ bire~rlngence - 110 x 10 3; and crystallinity -21.6%.

In TABLE IIIA, the e~ect o~ draw ratio on drawn yarn properties 18 illustrated.

TA~LE IIIA

Draw_Ratlo _ _1.65 1 60 1 54 Denler 209 218 226 Tenaclty gpd 8.15 7.53 7.12 Elongatlon % 8.4 8.9 10.4 Inltial Modulus gpd/100O 123 115 115 Hot Air Shrlnkaga ~ 350 F 12.0 12.4 12.0 2 ~ 3 ...... ...

, In Table IIIB, the effect of the heating method during stretching is illustrated (the draw ratio was 1.65 and the yarn was not relaxed).

TABLE IIIB
Hot Air Feed Hot Draw In$tial Shrinkage Roll Plate Roll Denier Tenacity Elon~ation Modulus 350 F Temp. Temp. Temp.
gpd % gpd/100% ~ C C C
334 4.09 71.7 55 11.8 (As Spun) 209 8.15 8.4 123 12.0 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 g.2 120 245 200 In Table IIIC, the e~fect o~ higher drawing temperatures and draw ratios is lllustrated (the ~eed roll is at ambient temperature and the draw roll ls at 240C).

TA~LE IIIC
Draw Ratio 1.76 1.72 1.70 1.67 1.64 _ 1.61 Denler . 195 194 199 203 209 208 Tenaclty gpd 9.50 9.22 8.89 8.73 7.76 6.71 Elongatlon 0 6.1 6.1 6.3 6.7 6.6 7.5 Hot Alr Shrinkage %-350F 6.8 7.0 6.8 6.5 6.8 6.5 Example IV
In the ~ollowing set o~ experlmental runs, a conventional polyester (PET, IV-0.92) was spun. In runs Nos. 1-5, the ~lbers were spun and drawn in accordance with the methods set ~orth in U. S.
Patent Nos. 4,101,525 and 4,195,052. Nos. 6-9 were made as follows:

2 ~ 3 PET with a molecular welght characterlzed by an I.V. of 0.92 was dried to a moisture level of 0.001~ or less. Thls polymer was melted and heated to a temperature of 295c in an extruder and subsequently forwarded to a spinning pack by a metering pu~p. T~is pack was of an annular design, and provided filtration of the polymer by passlng it through a bed of finely divided metal particles. After flltratlon the polymer was extruded through an 80 hole spinneret. Each spinneret hole had a round cross section with a dlameter of o.457 mm and a capillary length o~ 0.610 mm.

An insulated heated tube g meters in length was mounted snugly below the pack and the multi~llament spinninq threadllne passed through the entlre length o~ thls tube before being converged or comlng into contact wlth any guid- surraces. The tube was dlvided down lts langth into seven zones for the purposes o~ temperature control. Indlvldual controllers were used to set the air temperature at the center Or each o~ these zones. Uslng a combinatlon o~ process heat and the external heaters around the tube, indlvidual controller ~ettlng~ were selected to arrlve at a unlrorm air temperature prorlle down the vertlcal dlstance o~ this tube. In a typical situatlon the alr temper~ture was 155C at the top zone o~ the tube and the temperature was reduced in an approximately unlrorm gradient to 50C
at the bottom.

Approximately 10 cm below the tube the threadllne was brought lnto contact wlth a ~lnlsh appllcator whlch also served as the convergence gulde and the first contact that the yarn encountered. At the exit of the tube the cross section of the un-converged yarn was very ~mall due to the proxlmlty o~ the flnlsh gulde. Thls permltted a very s~all aperture to be used, thus minimizing the amount of hot air lost from the tube.

Followlng the appllcatlon o~ spin ~inish the yarn was taken to a pair of godet rolls and then to a tension controlled winder. Wlnd up speeds were typically ln the range 3200 - 4100 mpm.

Drawing o~ this yarn was e~ected in a second step, in which the as spun yarn was passed over one set o~ pretension rolls to a heated ~eed roll malntained at a temperature set between 80 and 150C. The yarn was then drawn between thsse rolls and a set o~ draw rolls malntalned at a set point chosen in the range 180 to 255C. A typlcal draw ratio ~or a spun yarn made at 3800 mpm would be 1.65, wlth ~ample~ ~pun at higher and lower speeds requlrlng lower or hiqher draw ratios, respectively.

The results are set ~orth in TABLE. IV.

2 ~ 3 __Feed Roll Ta~r~tur- C
25 ___ _ _ Inlti~l Initi~l Ten~city llodulu~Dr~n Y4rnTen-city llod~ Dr~ Y~rn gpdgpd~100% Shrinlt~ge X gpd g~100X Shr~nk~ X
Sp~rningSpu~ Y~rn 350-f 350-F
Speed3 I ret r~ ngence No. ~fsm) x10 3 5000 21.9 7.94115.007.30 5.96 ~8.005.30 26000 30,1 7.85118.007.00 6.90 103.006.~0 37000 45.2 8.36120.007.00 - 7.2~10B.00 6.50 48000 60.5 8.511~0.007.90 7.31113.00 6.00 5900~0 78 8.5~122.006.80 7.671 10.00 6.00 610500 104 9.52158.007.50 10.94173.00 7.30 711500 115 9.03150.006.80 9.52152.00 7.00 812500 121 9.08152.007.50 9.53160.00 7.30 913500 119 9.32154.006.00 9.58161.00 6.70 EXAMPLE V
Polyester wlth a molecular welght characterlzed by an I.V. of 0.92 waa drled to a moisture level Or 0.001%. Thl~ polymer was melted and h-at-d to a temperature Or 29~C ln an extruder and the melt sub~equently rorwarded to a splnnlng pack by a metering pump. Arter ~lltratlon ln a bed Or ~lnely dlvided metal partlcles, the polymer was extruded through an 80 hole spinneret. Each splnneret hole had a dlameter Or 0.457 mm and a caplllary length Or 0.610 mm. on extruslon the measured I.V. Or this polymer wa~ 0.84.

The xtruded polymer was ~pun lnto heated cyllnArlcal cavity 9 meters in length. An approxlmately linear temporature prorile (gradlentl was malntained over the length Or thls tube. At the center o~ the top zone the alr temperature was 155C and at the bottom o~ the :~ .
: . . .

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. Under these conditions a series of four spun yarns were made at different spinning (wind-up) speeds. These yarns are referred to as examples A through D
~n Table V. A.

In another serles of experiments the heated tube was shortened by taking out some o~ its removable sections. Examples E and F ln Table V. A were spun through 7 and 5 meter columns. Other polymers with di~ferent molecular weights (I.V.'s) were also spun on this sy~tem to glve Examples G and H. Example I in Table VA illustrates a case ln whlch 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 ~eed roll and a 245C draw roll.

In a further serles of tests the same spun yarn which was described in Example A was drawn uslng different feed roll temperature~. The results from testlng these yarns are given in Example~ A, J and K in Table V. 3.

v TABLE V. A
Spi~ning Conds Spin Temp Spun Spun Yarn Draw Drawn Yarn Example Len~th Speed C IV 8ir Crys~ Ratlo Ten I.M. HAS
mpm % gpd ~pd/100% ~-350~F
A 9 3200 155 0.84 .104 30.5 1.89 9.52 158 7.5 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 .ll9 38.9 1.72 9.32 154 6;0 E 7 3200 155 0.84 .lOl 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 C 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 llO 5.0 I 9 4100 125 0.84 .120 31.9 1.53 7.34 116 5.3 TABLE V. B
Feed Roll Draw Drawn Drawn Hot Air Exa~pleTemp C RatioTenacityI Modulus Shrlnk gpd gpd/100% ~-350~F
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 E~UUMPLE VI

In the ~ollowlng experlmental run, a conventlonal polymer, nylo~, w~ ~pun accordlng to the lnventive process and compared to nylon made by conventlonal processes.

The nylon made by the inventive process.was spun under the ~ollowing condltions: throughput- 37 lbs. per hour; spinning speed -2,362 ~pm: denler - 3500~ number o~ ~llaments - 68; spun relatlve viscosity - 3.21 (H2 S04) or 68.4 (HCOOH equlv.) ~uench air - 72 sc~m:
winding tension 80g; column length - 24 ~t; column temperature top 240C and bottom 48C. The as-spun properties o~ thls yarn were as ~ollows: tenacity - 0.95 gpd; elongatlon 235S; TEl/2 - 14.6.

y~
J ,~

Thereafter the yarn was drawn under the following conditions: draw ratio 3.03; draw temperature 90c. The drawn yarn properties are as follow6: tenaclty 6.2 gpd; elongation -70%; TEl/2 - 52; 10% modulus -0.87 gpd; hot air shrinkage t~AS) at 400F - 1.4~.

One comparatlve nylon was spun ln the following conventional ~ashion: throughput - 23.4 lbs. per hour; spinning speed - 843 fpm;
denier - 5556: nu~ber o~ ~ilaments - I80; spun relatlve 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:
tena~ity 3.8 gpd; elongation - 89~; TEl/2 - 33; 10% modulus - .55 gpd.

Another comparative yarn was spun in the ~ollowing conventlonal ~a~hion: throughput - 57.5 lbs. per hour; spinning speed - 1048 ~pm;
denler - 12400; numb¢r o~ ~ilaments - 240; spun relatlve viscosity -42 (HCOOH equlv.); quench air - 150 sc~m. Therea~ter, the yarn was drawn under tho ~ollowlng condltlons: draw ratlo - 3.60; draw temperature - 110C. The drawn yarn properties are a~ rollows:
tenaclty - 3.6 gpd; elongation - 70%t TEl/2 - 30.1; modulus at 10%
elongation - 0.8 gpds ~AS ~at 400F) - 2.0%.

EXAMPLE VII
In the ~ollowing experlmental runs, low I.V. (e.g. 0.63) and high I.V. ~e.g. 0.92) conventlonal polyester (l.e. PET) as spun yarn is compared with as spun yarn set rorth in U.S. Patent No. 4,134,882.
Examples 1-8 are low I.V. polyester ~PET) and are made ln the ~anner ~ 3 ~ . ,~ .

set forth in Example I. Examples 9-11 are hlgh I.~. polyester (PET) and are made in the manner set forth in Example v. Examples 12-17 correspond to Exampl~s 1, 5, 12, 17, 86 and 20 of U.S. Patent No.
4,134,882.

For each example, the spinning speed (fpm), density (gms/cc), crystal size (~, 010), long period spacing (LPS), blrefrlngence (biref.), crystal b~re~ringence and amorphous birefr~ngence are given.
The results are set ~orth in Table VII.
TABLE VII
Spin CS LPS
Sp~ed D~nslty 1 Crystal A~orphou~
No. ~f~m) ~q/cc ~ RBiref. Biref. Bir~f.

1 12500 1.3728 45 1470.1080 0.1982 0.067 2 13500 1.3742 45 1600.1060 0.1994 0.061 3 14500 1.3766 47 1550.1150 0.2004 0.070 4 15500 1.3788 50 1580.1120 0.2021 0.060 16500 1.3804 51 1450.1180 0.2035 0.066 6 17500 1.3827 53 1520.1240 0.2042 0.071 7 18500 1.3840 55 1470.1270 0.2055 0.073 8 19000 1.3841 54 1500.1300 0.2052 0.078 9 10000 1.3485 21 1920 0761 0.1824 0.063 10 10000 1.3653 43 1920.1047 O.lg30 0.075 11 12500 1.3749 52 1830.1215 0.1994 0.083 12 16500 1.3700 61 3130.0958 0.2010 0.045 13 18000 1.3770 73 3290.1082 0.2010 0.057 14 19500 1.3887 72 325. 0.1153 0.2030 0.054 15 21000 1.3868 68 3300.1241 0.2050 0.063 16 21000 1.3835 64 0.1236 0.1980 0.073 17 16500 1.3766 65 0.0965 0.2060 0.038 The pre~ent lnventlon may be embodied ln other specl~lc ~orms wlthout departlng ~rom the splrlt or essentlal attrlbutes thereo~ and, accordlngly, re~erence should be made to the appended clalm~, rather than to the ~oregolng specl~lcatlon, as lndlcatlng the scope o~ the lnventlon.

Claims (9)

1. An as spun polyester yarn being characterized by:
a crystal size less than 55 .ANG.; and an optical birefringence greater than 0.090.

2. The as spun polyester yarn according to claim 1 further characterized by:
a crystal size ranging from about 20 to about 55 .ANG.; and an optical birefringence ranging from about 0.090 to about 0.140.

3. The as spun polyester yarn according to claim 2 further characterized by:
a crystal size ranging from about 43 to about 54 .ANG.; and an optical birefringence ranging from about 0.100 to about 0.130 .ANG..

4. An as spun polyester yarn being characterized by:
a crystal size less than 55 .ANG.; and an amorphous birefringence greater than 0.060.

5. The as spun polyester yarn according to claim 4 further chracterized by:
a crystal size ranging from about 20 to about 55 .ANG.; and an amorphous birefrigence ranging from about 0.060 to about 0.100.

6. The as spun polyester yarn according to claim 5 further characterized by:
a crystal size ranging from about 43 to about 54 .ANG.; and an amorphous birefringence ranging from about 0.060 to about 0.085.

7. An as spun polyester yarn being characterized by:
a crystal size less than 55 .ANG.; and a long period spacing less than 300.ANG..

8. The as spun polyester yarn according to claim 7 further characterized by:
a crystal size ranging from about 20 to about 55 .ANG.: and a long period spacing ranging from about loo to about 250 .ANG..

9. The as spun polyester yarn according to claim 8 further characterized by:
a crystal size ranging from about 43 to about 54 .ANG.; and a long period spacing ranging from about 140 to about 200 .ANG..