CA1042168A - Polyester filament having lobes at ends of major axis - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Polyester filaments of 2 to 14 denier per filament having special oblong cross sections are particularly useful in pile fabrics for providing fur-like aesthetics. In compar-ison with previous polyester fibers, the new fibers provide an improved smooth, nontacky, resilient hand and pleasing luster, with freedom from fibrillation during processing or use of the pile fabric.

Description

104Zl~
This lnvention concerns improvements ln and relating to polyester fibers suitable for use in fur-llke plle rabrics.
Pile fabrlcs resemb~ing rurs have in recent years been manufactured from synthetic organic polymeric fibers and wldely sold for use in garments. These plle fabrics have been used both as liners for garments or as the actual outside sur-face Or the garment. The pile flbers have usually been acryl-icæ, modacryllcs, polyamides or polypropylene. Although it has been suggested, ror example, in Britlsh Patent Speclrlcatlon 1,198,819, to prepare a simulated sheepskln or lambswool pile rabric from conventlonal crimped polyethylene terephthalate ribers Or clrcular cross-section by sliver knlttlng techniques, in general, polyesters have been mlsslng from this 11st because Or problems relating to aesthetics. In particular, these fibers tend to develop a tacky hand when exposed to stock dyeing unless special precaution~ are taken. It has been round that the tacky ~uality results rrom a polye~ter trimer which exudes rrom the rlber durlng processing. The trimer and other low molecular welght materlals may be removed by carerul treatments, but this entails additional expen~e in fabric manuracture.
To overcome or minimize the above-mentioned diSrlcultles with prior-art polyester fur-like rabrics and permit the production Or such Sabrics having a smooth non-tacky hand, pleasing luster, low bending stirrness compared to round flbers, good resillence in the pile, and low propensity ror flbrlllation, the inventlon proYides a polyester rllament Or

2 to 14 denier having an oblong cross-section continuously along its length, wherein the cross-section has (a3 ma~or and mlnor axes Or symmetry which are perpendicular to each other, ~b) a ratlo Or length to width meagured along the axes Or from - 2 - ~

-, . ' -iO4;2~i8 1.4 to 2.4, (c) a lobe located on each extremtty o~ the ma~or axls which has a tip radius ratio rl/R Or 0.20 to 0.45, where rl is the radius of the lobe tip and R is the radius of a circle circumscribed about the oblong sectlon, (d) a lobe located on each extremlty Or the minor axis which has a tip radius ratio r2/R of 0.~ to 2.1 times the tip radius ratio of the lobes on the ma~or axis, and (e) indentations between the lobes, the shortest distince d between two of the indentations on opposite sides Or the ma~or axis being from 1.2 to 2.0 times the radlus rl of the lobes on the ma~or axis.
The present invention also includes the process Or making sliver-knit fur-like pile rabrics, by steps known per se, characterlzed by use Or the particular rilaments Or the invention de~cribed above.
The invention is better understood by rererence to the drawings in which:
Figure 1 is a diagram illustrating the method ror measuring the various rllament cross-section parameters;
Figures 2-4 illu~trate cross-sectlons ror several rllament shapes withln the scope Or the lnvention, the black dots on these cross-sectlons lndicating approximate centers Or curvatures ror the varlous parameters whlch wlll be descrlbed ln detall;
Flgure 5 ls a plan view Or a cluster Or three ad-Jacent splnneret orlrlces used for making a single fllament accordlng to Example I; and Figure 6 ls a plan view of a cluster Or three ad~acent splnneret orlrlces used ror maklng a slngle fllament according to Example II.
The cross-~ectlonal configuration Or ribers within ~he , ~04Z~68 invention may be determined rrom a photomicrograph Or the fiber cross-gection as illustrated in Figure l. The length of cross-section along the ma~or axis X is indicated by A. The width of the cross-section along the minor axis Y is indicated by B.
The ratio of length to width of the cross-section is A/~.
In the melt-spinning of filaments, the polymer tends to rlow so as to produce smooth curves or combinatlons of smooth curves and straight lines in the perlphery Or the cross-section.
Por the purpose oP measurement, the periphery may be considered to be composed of stralght lines and arcs of circles. In accordance with this concept, filaments of the invention have a lobe located at each end Or the ma~or cross-sectional axis, the extreme portion of the lobe being an arc Or a circle. The radius Or this lobe tip is indicated by rl at each end. Like-wise, a lobe is located at each end Or the minor axis Y of the cross-section; the radius ror each lobe tip being indicated by r2. While Figure l shows the center Or curvature ~or both lobes at the same point on the minor axis, this is not essential.
The centers Or curvature for the lobes on the minor axis may be separated, ror example, as in Figures 2 to 4. The circumscrib-lng radius ror the cross-section is lndicated by R. The tlp radlu3 ratlo rOr the lobes on the ma~or axis is rl/R and for the lobes on the mlnor axis is r2/R.
Another reature which is characteristic Or the cro~s-sectlon 18 r3, which is the radlus Or the circular arc between two ad~acent lobes. Whlle thls dlmenslon ls userul rOr construc-t~ns the theoretlcal outline Or the cross-section, an easler reature ror use ln mea~urement ls the alstance d, whlch ls the shortest dlstance between two lndentatlons m8asured across the maJor axls Or the rlber cross-section.

~04~
According to the invention, the ratio of length to wldth A/B o~ the cross-section is from 1.4 to 2.4 and the tip radius ratio rl/R for the lobes on the ma~or axis is ~etween 0.20 and 0.45. The tip radius ratio of the lobes on the minor axis i8 from 0.~ to 2.1 times the tip radius ratio Or the lobes on the ma~or axls. The cross-sectlon must be properly indented between lobes to provide the desirable properties Or the inven-tion; for this reason, the shortest distance d between two lndentations on oppos~te sides of the ma~or axis is rrom 1.2 to 2.0 times the radius rl Or the lobes on the ma~or axis.
While the above features may appear to be compllcated, they are quite simple to measure on enlarged photomicrographs Or cross-sectional views and the stated parameters are critlcal for obtalnlng the desirable flber and plle fabric properties.
Each Or the Figures 1 to 4 show cross-sectional shapes wlthln the scope Or the lnventlon. The measurements for each Or these are shown in Table 1.
The preclse reasons for the unusual comblnation Or ~ -properties Or the lnvention are not completely understood but a few general prlnciples have emerged ln the course Or developlng the rlbers Or the lnvention. First lt is necessary to have surrlclent lndentatlons ln the cross-sectlon to permlt hiding Or trlmer and other low molecular welght materlals present in polyester ~lbers. When synthetic flbers are lncorporated ln fur-llke pile rabrlcs, the pile rabrlcs are lroned and stroked very vlgorously wlth a rur lron to remove rlber crlmp thereby provldlng a smooth hand rOr the plle fabrlc. Thls lronlng operatlon tends also to deposit the low molecular weight mate-rials ln the grooves Or the riber thereby removlng lt rrOm the broad tactlle surfaces Or the flber. The resultlng rabric has .

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1(~4~68 an exceptionally smooth pleasant tactlle hand.
Another guideline of the invention is to avoid pro-vidlng large areas Or finger contact. For this purpose the cross-section of the filament Or the lnvention is designed so that it does not pack closely with ad~acent filaments.
The denier per filament~ which ls between 2 and 14, and the oblong cross-section of the fiber are important for providing fur-like fabrics with a soft feel but which still have resilience in the pile. Filaments with oblong cross-section are more satisractory for thls reason than filaments Or gener-ally round cross-section of the same denier per filament. The oblong cross-section filaments tend to bend easily in at least one dlrectlon providlng a soft hand. Ir denler is at least 2 and no more than 14, the rur-like fabrlcs have sort hand and good resillence.
Fllaments Or the lnventlon have a pleasant luster becuase they have a lobed surrace. Another lmportant feature Or the lnventlon ls avoldance Or fibrlllation. The tlp radlus ratio Or the lobes and the relatlve slzes Or the ma~or and mlnor lobes appear to have bearlng on thls quallty. Polyester rllaments whlch are too hlghly lndented or whlch have thln rlns along the length tend to rlbrlllate when passed through the fur lron, and durlng the llre and use of the garment. The fibril-latlon ln turn makes a garment unsatls~actory because o~ the matted appearance, partlcularly around the collar. The rllaments o~ the lnventlon avoid ribrillation by havlng a large mass at the center Or the cross-sectlon, by avoldlng excesslve indenta- -tion, and by requirlng a tip radlus ratlo above 0.2 for the lobes on the maJor axis.;
In the ~ollowlng Examples seven plle rabrics are 104;~

prepared; six withln the invention and one, for comparison, outside the invention. The cross-sectlon parameters Or the flbers used in each fabric are summarized in Table 3.
EXAMPLE I
A multifilament yarn of polyethylene terephthalate continuous filaments was melt-spun at 305C. from a polymer containing 0.1~ titanium dioxide having a relative viscosity of 21 determined for a ~olution of 80 mg. of polymer in 10 ml. of hexa~luoroisopropanol solvent at 25C. The polymer was extruded at the rate of 8.5 lbs./hr. [3.~6 kg./hr.] through a splnneret having 36 clusters of diamond-shaped orifices, there belng three diamond-shaped holes in each clu~ter. The three oririces within each cluster were closely spaced to permit melt coalescence immedlately downstream of the orlfices. A plan vlew Or a single ~ ;
cluster ls shown in Figure 5. The length Or the central diamond-shaped orifice in the cluster measured along the race of the spinneret was 0.020-inch [0.51 mm.] and the wldth was 0.012~
lncb [0.30 mm.]. The two orifices located on each ~lde of the central orlflce were 0.016-lnch C0.41 mm.] long and 0.009-lnch [0.23 mm.] wlde. The three orlrlces ln each clu~ter were sep-arated a dlstance Or o. 003-lnch [0.076 mm.] and were located ln a stralght row with thelr longest dlmen~ion~ parallel as indlcated ln Flgure 5. The multifilament yarn produced rrom -~
the 36-cluster splnneret was wound up at 1200 yard~/mlnute ~1100 meters/mlnute]. The wound-up yarn at this polnt was 530 denler with 36 rllaments. (Denler per rllament was 14.7).
About 100 ends Or yarn were comblned to produce tow o~ about 53,000 denler. Thls tow was drawn in 90C. water to obtaln tow having rllaments Or 4.6 denler per rllament.
Samples Or the tow 10 inches ~25 cm.] ln length had the following propertie6: tenacity, 4.0 gpd; break elongation 31%, boil-o~f shrinkage, 2.1%; and dry heat 6hrinkage at 196C., 7.2%. m e tow was then pasqed through a ~tuffer-box cri~per. The fila~ents a~ter this point had 9 cri~ps per inch [per 2.54 cm.~ and the denier was 4.6 per filament.
m e crimped tow wa~ cut to ~taple 1.25 inches [3.18 c~.]
in length.
m e drawn fila~ents prepared from the three-diamond ori~ice~ had a scalloped oval cros6-section with the rollowing para~eters: A/B = 1.6; rl/R = 0.33; r2/rl = 1.34;
and d/rl 3 1-64~ The cross-scctions were obtained by e~- -bedding a bundle o~ fila~cnts in a re~ln nedlu~ and cutting ~ith a ~lcrotome. The resulting slices ~ere observed in a ~icroscope under an iomer~ion oil and were then photo-graphed and enlarged ror measure~ent.
The staple fiber~ ~ere stock-dyed at 250F ~121C3 under pres~ure using 3 8ra~s per liter Or a ~odifled liquid biphenyl as d~e carrier and the rollo~ing dlsperse dye~
(% based on the ~abrlc ~eight): 2.7% Latyl Bordeaux B
(Color Index - Disperse Vlolet 26); 3.1~ Latyl Ceri~e N
(Color Index - Dlsperse Red 60); and o.8% Latyl Brown MS
(Color Index - Disperee Bro~n 2). The dyebath ~as drained arter th- teuperature had cooled to 160F [71C.]. No scouri~4 step ~as e~ployed arter the dye cycle. The resulting ~ibers ~ere maroon in color after tu~ble drying. These ribers ~ere proces-ed into sliver.
Tho above d~ein~ condltlons have been sho~n to leave a tac}y, lo~ olecular ~ei p t ~aterial 0n the surrace Or round rlbers. In contrast, although the 8an@ tacky ~aterial was rou~d pre~ent a8 partlcles on the surrace of the scalloped-oval cress-~ectlons Or the ribers Or this exa~ple, the ~aterl~l did not adversely ar~ect the aesthetic properties Or rur-li~e fabric prepared rrO~ these ribers. Tb avoid 8 tacky reel in plle - . ~ . . . . . .. .

iO4;216~

fabrlcs made with round fibers, it has usually been necessary to cool the bath to only ~hout 190F.[88C.] berore separating fiber from bath ~nd to scour the resultin~ ribers in a separate operation at close to the boiling point.
A sliver knit fabric was prepared from the above dyed staple as follows. Flrst, the dyed staple was processed on a woolen cara to proauce a 125 grain sllver. The sllver was then fed to a Wildman Maxi-Plle sliver knit machine. The machine is similar in basic principle to the machine depicted in U.S. Pat.

3,516,265 Por furs Or uneven density, but in the present case furs of uniform density were prepared. Sufficient staple fiber was picked up by the machine to give a knit tubing with a total weight of 8.5 oz./linear rt. [0.79 kg./linear meter]. The backing yarn ror thls fabrlc was a singles yarn with a cotton count of 14 made of polyethylene terephthalate homopolymer staple wherein the polymer had a relative vlscoslty o~ 23. The fllaments were 3.0 denier per filament and 2 lnches [5.1 cm.]
ln len~th.
Following knitting, the tubing was slit and back-coated with an acrylic resin latex, then heated to cross-link the resin and to dry. The resulting sliver-knit rabric was then rlnlshed ln the followlng sequence: (1) sheared in two passes to 7/16-lnch ~1.1 cm.~ pile length; (2) passed ~our times under a rur lron slmllar to that shown ln U.S. Pat. 3,557,415, otherwl~e known as an electrlfier cyllnder. The cyllnder was malntalned at 380F. tl93C-]- The plle rabric was passed under the lron at 3-1/2 yards per mlnute t3.2 meters/mlnute] at moderate pressure. Arter 4 passes, the crimps at the ends Or the plle fibers were substantlally remo~ed as desired; (3) resheared and wire-brushed, 1 pass; (4) resheared wlthout ~042168 brushlng; t5) ironed again at 380F. [I93dC.], 6 passes; (6) resheared 7/16 inch ~l.l cm.~, twice; (7) ironed at 300F.
[149C.] to polish, twi~e; and (8) sheared at 7/16 lnch [l.l cm.], twice.
The resulting ~abric had a pleasin~ luster and the hand Or the fabric was non-tacky- The pile was soft and re~llient. There was no evidence Or rlbrillatlon, i.e., no spllt ~iber ends observed in mlcroscoplc examlnation of the fabric. The hand was much less tacky than for similar ~abric made rrom round rlbers. Other properties of the rabric are shown ln Table 2. It wlll be noted rrom Table 2 that the rabric contained o.85S of an extractable material which is largely in the form Or surrace deposits of polyester trlmer.
A stereoscan photomlcrograph showed that the surface deposits were prlmarlly ln the grooves Or the fibers. Apparently, sur- -race deposlts ln thl3 location were not avallab}e to ringers touohlng the plle rabrlc. Pile rabrlcs of round ~lbers wlth slmllar amounts Or extractables were taoky ad unpleasant.
EXAMPLE II -- Fllaments wlth sGalloped oval cross-seotlon were pre-pared ~rom a dlrrerent type o~ splnneret, but were otherwise prepa~od as ln Example I. In thls oase the splnneret orlrice oonsl~ted Or 36 olusters wlth 3 round holes each. The 3 holes in eaoh cluster were lnterconnected by channels as shown ln ; Flgure 6. The outer holes were 0.008 lnch ~0.203 mm] in dla-- ~ ~eter and the large center hole was 0.0105 lnoh [0.267 mm~ ln . ::
dlamoter. The connectlng channels were about 0.0025 lnoh 0.0635 mm~ ~lde and 0.004 lnoh ~0.102 mm~ lonR. The outer hDles ~ere each centered 0.0133 lnoh [0.338 mm] rrOm the center ~: -- 30 Or the oenter hole. ; o . : , ; ~:; . .
~ ' 10 ' ' ' ,: ., .

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., . . .. .. . . .. - . ,. ... .. ,.... . -~f~4j~
The resulting rila~ents had a bundle tenacity o~ 3.3 gpd, elongation at break of 28~ and boil-ofr shrinkage of 1.1%.
The dry heat shrlnkage of the uncrimped drawn tow at 196C. was 6.5~. The cross-sectional measurements for the flla~ents were A ~ = 2-04; rl ~ = 0.33; r2/rl = 1.64; and d/rl = 1.54. After pa~slng through the stuffer-box~ the fllaments had 9 crimps per inch (per 2.54 cm). The filament denier was 4.7. The cut staple flbers were 1.25 lnches (3.17 cm.) long. The filaments were stock-dyed to produce a gray color. The dyeing conditlons were otherwise the same as ln Example I and no after-scour was used. The fabric was finished in a manner slmilar to Example I.
The ~abrlc was slmllar in aesthetic appeal. Propertles of the ~ - -fabric are shown in Table 2. The fabric had a non-tacky hand desplte the presence Or trlmer a. shown by 1.0% extractable ~;
materlal.
EXAMPLES III-VI
Several dlfferent types of spinneret and melt spinnlng conditionq were employed to make several types Or filament with scalloped oval cross-sectlon. These rilamentq were processed as ln Examples I and II. Sliver knlt rabrlcs were prepared.
The fllament cross-sectlonal measurements and properties o~ the rabrlcs are described ln Table 3. It wlll be noted that all Or the Plbers ln Table 3 except the comparatlve Example V produced acceptable fabrlcs. m e flber Or ~xample V had a ratlo Or d/rl Or 2.16 whlch is outslde Or the lnventlon, and the pile rabrlc Or Example V had a tacky hand. The pile fabrlc~ Or E~amples III, IV and VI had a non-tacky, soft and reslllent hand.
It was found that the rlbers Or Examples III, IV and Vl f~brll-lated less than a trllobal polyester flber havlng a modlflcatlon ratlo (a8 deflned ln Holland U. S. Pat. 2,939,201) of 1.8 and the ., - . ,:
- 11 - .'.'.,'.

A

same denler per rilament.
EXAMPLE VII
Another sliver knit rabric was prepared having a pile surrace composed of (a) 50S by weight of the 3.4-denier flbers Or Example III and (B) 50% o~ 14-denler fibers of 2 lnch [5.1 cm.] length wherein A/B was 1.79, rl/R was 0.32, r2/rl was 1.24, and d/rl was 1.56. The 3.4-denier flbers were dyed an off-white belge shade and the 14-denler fibers were dyed a dark brown.
The fabric was knit and rinished as ln Examples I and II, but was sheared to 3~4-inch [1.9-cm] plle helght. The flnished fabric had a pleasing luster, and a sort, resllient, non-tacky hand. The 14 dpr rlbers, belng longer, were more promlnent at the surrace Or the plle, and the resultlng fabrlc was slmllar ln appearance to natural rurs. The 14 dpf rlbers served as guard halrs, belng slmilar to the guard halrs Or natural furs ln appearance and ln feel.

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t ! , ' , ~'~';, ~ '. . ' :' :' ' , ' -: ` : : , , ~ 12 - ~ -`-,;: ' ' ,. ' iO42168 CROSS-SECTIONAL MEASUREMENTS FOR FILAMENTS SHOWN IN FIGURES_1-4 Fig. No. A/B rl/R r2/rl d/rl 1 2.0 0.3 1.67 1.84 2 2.0 0.2 2.0 1.18 3 2.0 o.38 2.0 1.86

4 1.5 0.4 1.5 1.98 TABLE II
PROPERTIES OF SYNTHETIC FURS PREPARED IN - :
- EXAMPLES I AND II
Ex. I Ex. II ~
Total rabrlc welght, oz/yd2 [g/m2] 14.8[503] 14.0[475] ~ -Shaved pile wel~ht ~ loS, oz/yd2 tg/m ] 6.8~231] 6.5[220]
Welght Or knlt backlng, oz/yd2 tg/m2] 8.0~271] 7.5[254]
Fabrlc thlckness ln rlnished state (arter latexlng),lnches ~ Gm .] 0.44[1.12] 0.49~1.29]
~ Weight 10s8 ln Wyzenbeeck -: :
- abraslonJ ~rter 50 cycles/arter ,. ~ 10 X oz/yd~ cycles - 0.47/.74 0.60/l.10 :
20 Extractable wlth carbon tetra-chlorlde, ~ by wt. Or dyed staple o.85 l.o .~ . .
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~. ~ . -TA B LE III
CROSS-SECTION PARAMETERS OF PILE :~IBERS O~ ~XAMPLES
EXample Denier per (2) ~o.(l) Filament A/B r~ 2/rl- d/r I 4.6 1.6 0.33 1.34 1.64 II 4.7 2.04 0.33 1.64 1.54 :
III 3.4 1.64 -35 1.01 1.42 IV 3.3 1.59 0.40 1.08 1.74 v(l) 3 4 1.74 0.38 1.38 2.16 . -10 Vl 2.7 1.60 0.35 1.26. 1.84 VII(A) 3.4 1.64 0.35 1.01 1.42 (B) 14.0 1.79 0.32 1.24 1.56 1. Example V 18 a comparative exampleJ outslde the scope of the lnventlon.
2. r2/rl 18 the same as the ratlo of r2/R to rl~R.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A polyester filament of 2 to 14 denier having an oblong cross section continuously along its length, characterized by:
(a) Major and minor axes of symmetry which arc perpendicular to each other;
(b) A ratio of length A to width B, measured along the axes of symmetry, of from 1.4 to 2.4;
(c) A lobe located on each extremity of the major axis which has a tip radius ratio r1/R of 0.20 to 0.45, where r1 is the radius of the lobe tip and R is the radius of a circle circumscribed about the oblong cross section;
(d) A lobe located on each extremity of the minor axis which has a tip radius ratio r2/R of 0.8 to 2.1 times the tip radius ratio r1/R of the lobes on the major axis; and (e) Indentations between the lobes on the major and minor axes, the shortest distance d be-tween two indentations on opposite sides of the major axis being from 1.2 to 2.0 times the radius r1 of the lobes on the major axis.