CA1295800C - Texturing yarns - Google Patents

Abstract

ABSTRACT
Modifying a polyester with trimesic or trimellitic acid or its derivatives as chain-brancher to provide a draw-texturing feed yarn that can be draw-textured at a speed of 1,000 mpm without excessive filament breaks, and with other advantages in the resulting textured yarns,such as improved bulk and dyeability over unmodified polyester yarns textured under similar conditions, and preferably without sacrificing dye uniformity.

Description

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Improvements Relating to Texturing Yarn6 TECHNICAL FIELD OF THE INVENTION
This invention concerns improvements in and relating to texturing yarns, and is more particularly concerned with improved polyester draw-texturing feed yarns havin~ ~ capability of being draw-textu~ed at high speeds without exce~sive broken filamentci and with other advantaqes, to such high speed process oi- draw-texturing, and to ~ proce~s for preparing ~uch feed yarn6.
BACRGROUND OF THE INVENTXON
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The preparation of textured polyester ~ultifilament yarns has been carried out commercially on a worldwide scale or many years. The simultaneous draw-texturing by a fal~e-twist texturing process of partially oriented feed yarns of low crystallinity prepared by spin-orientinq, i.e., withdrawing the ; melt-spun polye6ter fil~ment6 at high withdrawal ~peeds of, e.g., 3,000 ypm, was disclosed by Petrille in U.S.P. 3,771,307, and the feed yarns were disclosed by Piazza and Reese in U.S.P. 3,772,872. Use of these spin-oriented feed yarns has ~ade possible siqnifican~
increas~s in texturing speeds. ~n about 1970, commercially-available texturing machines (false-twist texturing) were capable of maximum ~peeds only of the order of about 200 mpm (meters per minute). For sever~l years now, owing ~o improvements in machinery design, draw-texturing machines have been commercia}ly available with a capability of operating at very high speeds of, e.g., 1,000 mpm or more. Despite the availability of such machines, capable of machine operation at such desirable very high ~peed~, commercially-available draw-texturing polyester feed yarn~ (DT~Y) have not been textured commercially at the very high speeds of which the ~achines ~re capable. This is ~ainly because of the excessive number of ~roken ~ilaments produced at these very high .~ .
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speeds. Any broken filaments are undesirable, ~ince they may cause difficulties, and even yarn breaks, during subsequent processinq, and also fabric defects. The number of broken filaments that ~ay be tolerated in practice will depend upon the intended use for the ¦ textured yarn and eventual fabric. In practice, in the ¦ trade, the ends of the bobbin are examined for broken ; ¦ filaments, and the number of protruding broken filaments is counted so as to give a measure of the probable number of broken filaments in the yarn of that package. The total number o~ these broken fil~ments counted is then divided by the nu~ber of pounds in the package and expressed as ~FC. ~or certain end uses, the ~aximum that - can be tolerated i6 between 0.5 and 0.6 BFC, i.e., between 15 5 and 6 broken ~ilaments for every 10 lbs. of polyester yarn, it being understood that one break will probably count as two broken filaments. Thus, for any texturer ¦ having a texturing machine capable o~ operation at 1,000 mpm or more, if the polyester draw-texturing feed yarns commercially available cannot be processed on ~his machine at more than about eso mp~ without significantly exceeding the desired maximum (e.g.,about 0.5 aFc)r he will be forced in practice to operate his machines at this speed of 850 mpm instead of increasing the speed to the maximum capability of the machine. Despite the obvisus commercial incentive to provide polyester draw-texturing feed yarns capable of being draw-textured at ~peeds of more than 1,000 mpm without excessive BFC, however, hitherto, this problem of providing a commercially-satisfactory feed yarn has not yet been solved.
I have found it possible to increase texturing peeds without causing excessive broken filaments by increasing the withdrAw~l ~peed used to obtain the desired 6pin-orientation in the feed yarn. Such feed yarn~, prepared ~t relatively high withdrawal speeds o 4,000 mp~, have not been textured commercially on a large :
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scale because of accompanying disadvantages, mainly that the resulting textured yarns have not been ~s bulky a~
yarns that are already available commercially. ~ulk is generally measured as CCA, a Yalue of at least about 4 being considered desirable, or as TY~, ~ value o over 20 being considered desirable, generally, ~t this time.
The problem that has ~aced the industry, therefore, has been to provide a polyester ~ultifilament draw-texturing feed yarn (DTFY) that is capable of being draw-textured on existing commercial ~achines at a 6peed of at least 1,000 ~pm and yet of providing a pac~age of textured yarn with, by way of example, not more than about 0.5 BFC and over 20 TYT, it being understood that such fiqures depend very much on economic and other commercial considerations and on what competitors are prepa~ed to offer at any time. Generally, with the passage of time, the demands of any indu~try tend to increase.
SUMMARY OF THE INVENTION
The present invention provides a so}ution to this problem. In one aspect of the invention, there is provided a process whereby ~n improved new polyester feed yarn can be draw-textured at high speeds to give yarn~ of satisfactory texture without excessive BFC. In another aspect, improved new polyester feed yarns are provided, whereby this problem can be solved. In a further aspect, there is provided a process for prep ring these improved new feed yarns. ~n a further aspect, u~e of ~he feed yarns c~n provide other advant~ges, even when increased ~peed of texturing is not necessary or desirable.
According to one aspect of the invention, there _ is provided a continuous process for preparing polyester draw-~exturing feed yarns, involving the ~teps o~ first forming a molten polyester by reac~ion ~a) of ethylene glycol with terephthalic acid and/or esters thereof, followed by polycondensation (b), these reaction steps being carried out in the presence of appropri~te catalysts : ,:
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~herefor, and then ~elt-~pinning the resulting molten polyester into filaments and withdrawing them at a speed of about 3,000 to 4,000 mp~, preferably a~ speeds in the lower portion of thi~ range, such as about 3,000 eo 3,200 mpm, to provide partially oriented yarn~ of low crystallinity, wherein the polyester i~ modified by introducing into the polymer, ~5 a ~olution in ethylene glycol, ~ substance selected fro~ the group con~i~ting of trimesic acid, trimellitic acid or an es~er thereof in 1~ amount as indicated ~pproximately by the line AB of Figure 1 of the accompanying drawinq.
: According to another aspect of the invention, there i5 provided a partially orien~ed polyester multifilament draw-'texturing feed yarn of low crystallinity, a5 ~hown by a boil-off 6hrinkage of about 45% and an elcngation to break of about 155%, cons$6ting essentially of polymerized ethylene terephthalate re~idues chain-branched with trimellitate or trimesate residues in amount about'6 MEQ, and of relative viscosity about 21 LRV. Alternatively, the boil-off shrinkage may be about 20-25~, the elongation to break about 133%, and the amount o trimesate or trimellitate residues about 4 MEQ. ~he ' elongation (to break) is a measure of orientation (a6 i6 birefringence), the elongation being reduced as th~
' 25 spin-orientation 1~ lncreased, while the shrinkage 16 : affected by the cry~tallinity, as well as the orientation, and i5 reduced as the crystallinity increases. Thu6, there i~ provided a multifilament draw-texturing feed yarn that has been prepared by polymerizing ethylene and ter~phthalate derivatives with trimesate or trimellitate _ residues acting a~ chain-brancher and by spin-orienting at a withdrawal 6peed of at least about 3,000 to 4,000 ~pm, preferably a'lower ~peed, ~uoh a~ about 3,000 to 3,200 mpm, and that i~ capable of being draw-textured at a speed of at least 1,000 ~pm to provide a package of text~red yarn with ~ot more than about 0.5 ~FC and a ~YT
o~ over 20.
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- s -According to a further aspect of the invention, there is provided a process for preparing a false-twi~t textured yarn, wherein a multifilament polyester feed yarn is subjected to simultaneous draw-texturing at a ~peed of at least 500 ~p~, the feed yarn con~ists essentially of poly~erized ethylene terephthalate residues and of trimesate or trimellitate residues acting as a chain-brancher, and the resulting packagle of textured yarn has not more than about 0.5 BFC and oYer 20 TYT.
A~ will be apparent, the new feed yarns and their process of preparation make possible the provisaon of textured polyester yarns having increased dye-uptake and/or l~proved cr~mp, a~ co~pared with prior commerclal polyester yarns tex~ured under comparable conditions.
Ac will be explained hereinafter with reference to the drawings, the amount of chain-brancher will depend on various considerations, especially the spinning speed, since it will generally be des~rable to use as ~uch chain-brancher a6 pos6ible to obtain increased advantages in certain respects, whereas the amount should not be so much as will cause spinning difficultie6, and thi6 will depend on the withdrawal speed in the 6ense that the desircd amount o chain-brancher will be reduced as the withdrawal Epeed i~ increased. Furthermore, an adv~ntage in dye uniformity of the textured yarns (~nd fabric~ has been obtained by withdrawing the filaments of the feed yarns at lower 6peed~ within the ~peed range indicated.
E~RIEF DESCRIP~ION OF THE; DRAWINGS
Figure 1 i5 a graph showing the relationship of the withdrawal speed in ypm and the amount of chain-brancher in MEQ.
~ Figure 2 is a graph plotting crimp propertie~
- ITYT) against the amount of chain-brancher used in E~ample 2.

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The preparation of the feed yarn is preferably by a continuous process in which the steps of polymerization and spinning are coupled together,-because the alternative process that has been carried out in some plants of first ma~ing the polyester ~nd then extruding it in the for~ of ribbons whieh are cooled with water and cut into pellets or flakes, which are then remelted for a separate process of spinning into filaments, can introduce uncertainties and problems, which can lead to variability in the resulting feed yarn filaments. It will be emphasized that uniformity of the polyes~er filaments in the feed yarn is of great importance in achieving high draw-texturing spee-ds without excessive broken filaments.
An important element of the invention ls believed to be the use of trimellitic acid, or trimesic acid, or a derivative thereof in small amounts ~e.g. 4-6 MEQ) as a chain-brancher in the process of preparation of the polyestet, which is accordingly a copolymer. It is believed that such çhain-branching has not previously been used commercially for the objective of producing a feed yarn capable of being draw-textured at high speeds, e.g., of 1,000 mpm, without excessive broken filaments, e.g., not more than about 0.5 BFC, while giving de~irably bulky yarns, e.g. of TYT over 20. It is not, however, new to suggest the use of chain-branchers for other purposes.
For instance, MacLean et ~1., U.S.P. 4,092,299 suggests a high draw ra~io polyester feed yarn and its draw-tex~uring and companion U.S.P. 4~,113,704 suggests a polyester ~ilament-forming polymer and its ~ethod of production.
Since the two disclosures are practically identical, only U.S.P. 4,092,299 wi}l be discussed.
MacLean ~t al., U.S.P. 4,092,299 suggests ;~ improving productivity by using a chain-brancher in such amount that the polyester has 1-15 or 2-14 ~ ~ microeguivalents ~f reactive branching sites per gram of : :
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polymer (MEQ), and preferably 5-12 MEQ. The increased productivity is obtained by increasing the draw ratio during draw-texturing and/or increasing the withdrawal speed during filament formation, because the orient~tion (birefringence) of the feed yarn i5 reduced by using chain-brancher. The optimum level of chain branching is discussed in column 11, and wili depend on ~any factors.
Pentaerythritol is suggested as the preierred chain brancher, but is not desirable accordincl to the present invention, because it vDlatizes during polymer preparation. We have found that use of such volatile chain-brancher leads to problems and consequential lack of uniformity in the resulting filaments for the draw-texturing feed yarns. Although a volatile chain-brancher, such as pentaerythritol, may be quite adequate for operation at low texturing speeds and for MacLean's objective of increasing productivity, it is not a solution to the problem of providing a draw-texturing feed yarn capable ofi draw-texturing at a speed of, e.g., 1,000 mpm without excessive broken filaments, e.g., not more than about 0.5 BFC, while giving a desirably bulky yarn, e.g., over 20 TYT.
According to the present invention, we have found it desirable to use a chain-brancher that is adequately stable (both in monomer form during processing and polymerization and in polymeric form during formation of the poly~er and spinning into filaments and subsequent processing), not so volatile as to cause pro~lems and variability during preparation of the polymer, and that is soluble in the catalyzed glycol for ease of addition to the reaction. Trimellitic acid and its ester derivatives fulfill all these functions, and it is believed that trimesic acid and its ester derivatives would have similar unctions and advant~ges. ~here are ~wo main routes to preparing polyethylene te~rephthalate polyesters, namely ester interchange of dimethyl terephthalate (D~T) with -B ~2535~

ethylene glycol (EG) to form a prepolymer, followed by further polymerization, or reaction of terephthalic acid ( ~PA ) with EG to form the prepolymer, followed by further polymerization. If the DMT route is used, then an ester, such as trimethyl trimellitate (TMTM), will be preferred, whereas trimellitic acid (TMA) will be preferred generally for the TP~ route.
MacLean is not limited to the use of pentaerythritol, but covers other chain-branching agents having a functionality greater than 2, that is containing more than 2 functic~nal groups such as-hydroxyl, carboxyl or ester. Accordin~lly, other polyhydroxy chain branchers are mentioned, and aromatic polyfunctional acids or their esters (column 7). Trimesic acid, trimethyl tcimesate and tetramethyI pyromellitate are specifically men~ioned in lines 41-42, but are not used in the Examples. In Table IV, column 12, trimer a~id is used in amounts 11,~00 and 23,600 ppm (said to be 6.5 and 12.9 MEQ, but calculated instead 35 12.9 and 25.1 MEQ, respectively) and ~ellitic acid (benzene hexacarboxylic acid) is used in amounts 9.B
and 14.7 ME0. The only texturing speed mentioned by MacLean is 200 ypm (column 10, line 15). The withdrawal (spinning) speeds vary between 3,4~0 and 4,400 ypm in Examples 2 and 4, and are 5,500 and 6,000 ypm in Example 6, and are otherwise 3,400 ypm. Productivity (MacLean~s objective), it was said, "definitely increases with spinning speed over most of the speed range capability of the equipment u~ed" (colul~n 11, lines 58-60), and it was impossible to determine whether the productivity curve continued to increase with 6pinning speed.
As will be 6een in the Examples, hereinafter, wherein the DMT ester interchange route i5 used to prepare the polyeste'r, the chain-brancher is conveniently dissolved in the catalyzed EG ~olution that is used in an otherwise conventional ester interchange reaction between DMT and EG using approprizte catalysts to prepare the .
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-9- 1295i~3Q61 prepolymer. Further polymerization (sometimes referred to as finishing) i5 carried out under vacuum with an approp~iate material such as phosphorus again in conventional manner to prepare a polymer of the required ~iscosity ~measured as LRV). The resulting polymer is then preferably passed continuously to the ~pinning unit with~ut intermediate conversion into flake and remeltingj and is spun to prepare partially oriented filament of low crystallinity at withdrawal speeds of 3,000 ~pm or ~ore, with particular care in the spinning conditions to provide uniform filaments, to minimize breaks during the spinninq or during subsequent draw-texturin~ operations at high speed.
TM~M has-three reactive carboxyl groups of which two are reacted in the molecular chain. The other one reacts to form a side chain which is referred to ~s a chain branch. ~f and when these chain branches realct with another molecule, a crosslink is formed. Obviously there ~re many more chain branches than crosslinks formecl. Also because there are only three of these (carboxyl) reactive s.ites in TMTM, there is only one for chain branching.
Therefore, the equivalent weight and the molecular weight are the sa~e. 0.15% by weight of TMTM (on the weigh;t of the polymer) is the same as 10500 ppm and is almost 6! MEQ
~5.~5). Similarly, 0.10~ of TMT~ (1,000 ppm) is almo~st 4 MEQ~ Trimesic acid h~s the same molecular weight ~B
tri~ellitic acid, 60 the ~ame vDlues apply.
As indicated above, and herein elsewhere, th~
amount of chain-brancher must be carefully adjusted, 1 30 especially according to the withdrawal speed, i~ the full benefits of the invention are to be obtaine~. Optimum amounts are indicated graphically as the line AB in Figur~ 1 of the accompanying drawings, plotting such optimum amounts ~as MEQ) against the withdrawal speeds (in ~ 35 ypm) for the equipment that I have used. It will bc ; ~ undersl:ood that so~e variation can be permitted, and the :,:: :
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exact optimum may well differ according to various factors, such a6 the ingredients and equipment used to make the polymer and the yarns, and operating preferences.
However, as the a~ount of chain-brancher increases, so does the ~elt viscosity generally inçreas~, and thi~ ~oon causes problems, particularly in spinni~g, so that spinning becomes impossible because of ~elt fracture.
However, it is generally desirable to use as ~uch chain-brancher as possible, consistent with the above, co as to obtain the indicated benefits in t:he textured yarns, especially of increased crimp and dye-uptake over yarns of unmodified polymer. Thus there is a rather narrow range of proportions of chain-br~ncher within which I prefer to operate. As indicated, ~his range decreases with the withdrawal ~peed used to make the DTFY, since the ~elt viscosity increases, ~nd accordinqly spinning problems increase with increased speeds. Furthermore, the dye uniformity of th~ textured yarn has been better when lower withdrawal speeds have been used within the indicated range. If this is i~portant, a withdrawal speed that is relatively low within the operational range is preferred i.e. less than 3,500 mpm, and especially about 3,000 to 3,200 mpm. This preferred relatively low speed is surpri~ing, being contrary to what I had expected from my ; 25 knowledge of this field and of the teaching in the art.
However, the 6peed should not be too low, since thi6 will lead to filaments that are unstable to heat, and that may cause problems of fusing together or mel~ing on the (first) heater of the texturing machine, or of string-up.
In this respect the desir~ble minimum withdrawal speed is ~ignificantly more than taught by Petrille and by Piazza and Reese in U.S.P. 3,771,307 and 3,772,B72 for un~odified (homopolymer) PET yarns. As indieated already, and is well known, the elongation (to break) generally decreases as the withdrawal speed increases, being a measure linverse) of the orientation. Thus an increase in , Z5~5 elongation (other parameters being kept constant~
generally indicates a tendency to instability of the filaments to heat, whereas a decrease in elongation ~imilarly indicates less dye uniformity. It will be understood that all the numerical parameters expressed herein will depend ~n the ingredient~, equipment and operating preferences to 60~e extent. The preferred value of 21 for the LRV is because too high a value will increase the melt viscosity ~nd this leads to spinning problems, as already explained. Too low an LRV, however, tends to reduce the tensile properties, especially the toughness of ~he filaments, and this leads to breaks during draw-texturing. Similarly, if the shrinkage is too low, this indicates too ~uch crystallinity, ~nd leads to ~ariability, which generally shows up first as reduced dye-uniformity, whereas insufficient crystallinity ~too high a shrinkage) leads to variability in other respects, and can produce filaments that are not sufficiently ~table to heat, as indicated above. So it will be understood that the spinning conditions must be carefully monitored, and the desired amount of chain-brancher must be care~ully selected, and is affected by the speed of withdrawal, which may be selected according to the properties desired in the eventual textured yarns. If dye uniformity i6 essential, then a lower speed of about 3,000 mpm m~y be preferred. If better crimp properties are more important, then higher withdrawal speeds may be preferred. A6 the ~ withdrawal speed rises, however, there comes a point when ; the presence of chain-brancher does not apparently continue to improve crimp propetties, although other advantages, such as of impro~ed dye-uptake will still 3pply.
The use of chain-brancher has been noted to provide significantly higher ~pinning tensions, than with unmodified polymer. This is believed to be an i~portant advantage in the process of the invention.
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As indicated, an important advantage in the resulting textured yarns, obtained by draw-texturing of the improved modified feed yarns of the present invention, is the low number of broken filaments IBFC) obtained even when the texturing is carried out at the very high speeds indicated. The resulting textured yarns also have other advantages. As can be seen from the Examples herein, the dyeability, or dye-uptake, is improved. This, in retrospect, may not ~eem so ~urprising, since there have been several prior suggestions of using other trifunctional chain-branching a~ents in polyester polymers in much larger amounts (0.5-0.7 mole percent, i.e. about 10 times as much~ in order to obtain better dyeability, oil-stain release or low pilling, as mentioned in column 1 of MacLean. ~owever, despite these general suggestions of improving such properties in the prior art, it is believed that no one has previously actually made a textured polyester fiber of improved dyeability by incorporating a trimellitate or trimesate chain brancher in the polymer used to make the DTFY.
A further improvement in the textured yarns, believed to be a result of the chain-branching according to the invention, is the improved crimp properties, a~s shown by the CCA and TYT va}ues in the Exa~ples. Thi 5 i S
an important advantage commercially. ~n practice, it is necessary to operate the draw-texturing process so a5 to obtain textured yarn having at least equivalent crimp ; properties to those that are already available ~ commercially. The crimp properties can be adjusted to ; 30 some exte~t by varying the draw-texturing conditions, and this can also depend on the skill and knowledge of the texturer, who ~ay be forced to reduce the ~exturing speed in order to improve the crimp properttes o the resulting textured yarn. Thus, a desirable objective ~or the texturer is to achieve or surpass the target crimp properties, while reducing his costs by operating at the maxlmum possible speed.

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The invention is further illustrated in the following Examples. The yarn properties are measured a~
in U.S. Patent 4,134,8a2 (Frankfort and ~nox) except as f~llows.
~FC (~roken Filament Count) is measured as indicated hereinabove in number of broken filaments per pound of yarn. In practice, a representative number of yarn pachages are evaluated and an average sFc is obtained by visually counting the total number of free ends on both ends, and dividing by the total weiyht of yarn on these packages.
TYT (Textured Yarn Tester) measures the crimp of a textured yarn continuously as follows. The instrument has two zones. In-the first zone, the crimp contraction of the textured yarn is ~easured, while in the second zone residual shrinkage can be measured. Only the first zone (crimp contraction) i5 of interest, however, for present purposes. Specific~lly, the textured yarn is taken o~f from its package and passed through a tensioning clevic~
which increases the ~ension to the desired level, 10 grams for 160 denier yarn (0.06 gpd). The yarn is then passed to a first driven roll, and its separator roll, to isolate the incoming tension from the tension after this first roll. This roll is hereafter referred to as the first roll. Next, in this first zone, the yarn is passed through a first tension sensor, and through an insulated hollow tube, which iB 64.5 inche~ (~ 164 cm) long bnd 0.5 inches ~1.27 cm~ in diameter and which i6 ~aintained at 160~C, to a second set of rolls, a driven roll and a separator, which isolate the tension in the yarn in the first zone fro~ that in the next zone, and to a third set of rolls, a driven roll and a separator roll, which further i~olates the tension in zone one from the tension in zone two. The cireumferential speed of roll three is 3~ et enough faster than roll two so that roll two imp~rts 2 grams tension to a 160-denier threadline (~ 0.013 gpd~, .

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and rolls tw~ and three are controlled by the first tension sensor at such speeds as to insure that the tension in zone one is that desired, (~ 0.001 gpd). When the yarn leaves the third set of rolls, it is passed through a second sensor and thence to a fourth set of rolls which isolate the tension in the ~econd zone ~rom any windup tension or waste jet. The ~peed of the fourth set of rolls is controlled by ~he second sensor and that tension is ~et at 10 gram~ for a 160-denier yarn or 0.0625 gpd. of course, the total tensions will chanqe with a change in denier of the textured yarn. As indicated, only the relative speeds in and out of the first zone are of interest in this instance.
The TYT is calculated as a percentage from the circumferential speeds V1 of the first roll and V2 of the second roll: -Vl - V2 TYT - x 100 CCA (Crimp Contraction) of textured yarns is determined ln the following manner: A looped skein having a denier of 5,000 is prepared by winding the textured yarn on a denier reel. The number of turns required on the reel is equal to 2,500 divided by the denier of the yarn.
A S00 gm. weight is suspended from the looped skein to initially straighten the ~kein. This weight is then replaced by a 25-gram weight to produce ~ load o~
5.0 mg/denier in the skein. The weiqhted skein i~ then heated for 5 minutes in an oven supplied with air at 120C, after which it i6 removed from the oven and allowed to cool. While still under the 5.0 mg~denier load, the length of the skein, Lc, is measured. The lighter weight is then replaced by the 500-gm. weight and the length of ~ 35 :~ -14-.

~' the skein, Le~ is measured ~gain. Crimp Contraction is then expressed as ~ percentage which is calculated by the formula:
CCA - ~ C x 100 Dye Uptake - Each yarn W3S knitt~d into a tubing using a L wson ~emphill rA~ knitter. The kn~t tubing wa~
scoured, dyed at 265'~ using Eastman Polyester ~lue GLF
(~isp~rsed Blue 27 No. 60767), rescoure~, dried, flattened and the light reflectance of the various sections of the tubing measu~ed with a Color Eye Instrument*, which is marketed by the Macbeth Corporation. Reflectance ~alues are conve~ted into ~/S values us~ng the ~u~elka-Munk function, which is the theoretical expression relating reflectance of dyed yarn ~in thls case in tubing), to the concentration of the dye in the ~iber. Sections of a "control yarn~ Dr~ knitted into each tubing 80 th~t all K/S values can be ratlonalized, i.e., exp~essed in ~ Dye Uptake" vs. this control as standard.

Copolymer or the new and improved ~eed yarn for draw texturing ~DTFY) i~ prepared by copoly~erizing di~cthyl ter~phthal~te ~DM~), ethylene glycol ~5) and about 4.3 MEQ trimethyl tri~ellitate ~TMT~) labout 4.3 icroequivalents per gra~ o~ DMT). 4.3~MEQ is 0.11~ of MSM per gram of copolymer. The T~TM is d~olved ~n and : added with the catalyzed glycol. ~t the concentration required, the TMTM 16 completely soluble ~n the catalyzed : 30 qlycol and neithe~ enhances nor inhibits the catalytic prope~ties of the mang~nese and antimony ~alts which are : used a~ catalyst~. Catalyst con~ents are ~dentical to ~ those us~d for ~tandard ~T. The required ~ount o~
.~ phosp~orus, either as an acid or salt, is ~dded when ~he ~xchange i~ complete and be~ore proceeding with : poly~erization to~nactivate the:manganese cataly~t dur~ng * denotes trademark -15-.. . .

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polymerization. 0.3% of TiO2 based on DMT is added, as a glycol slurry to the material, after the exchange is complete and before the polymerization, to provide opacity in the resultin~ DTFYS. It i5 found that the addition, exchange and polymerization process conditi~ns used f~r standard PET are acceptable. Indeed, the polymerization proceeds faster for the new copolymer. In the preparations used herein, both the copolymer and the standard (linear polymer) PET ~used as control) were prepared in a continuous polymerization process. It is found that the resulting new copolymer has a LRV slightly higher than that of the control, somewhat more than 21 vs.
; standard polymer of about 20.5. The new copolymer also had a slightly higher melt viscosity than the control.
lS This increased melt vi~cosity was not enough to cause problems in polymer making, polymer transport or spinning.
The polymer i5 pumped from the continuous polymerizer to the spinning machines where it is spun into the new and improved feed yarn for draw texturing.
The new copolymer is pumped through a filter pack and thence throuqh a spinneret which has 34 capillaries, each 15 x 60 ~ils (diameter x length).
Spinning temperatures are somewhat higher than those required for standard PET (about 300C vs. about 293C for the standard PET). The extruded filaments are quenched by passing room temperature air across the filaments below the 6pinneret, usinq the same cross-flow system as for the standard PET filaments. The amount of air flow across the filaments is adjusted to obtain the best operability.
Finish is applied after the filaments are quenched.
Filaments are then converyed into a threadline and handled as a threadline thereafter. This threadline is passed at ~,000 ypm (3,600 mpm) around the first godet, called a feed roll, thence to a second godet, called a let-down roll, through an interlace device and thence to an appropriate wind-up at about 4,000 ypm. The ,:

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circumferentinl 6peed of the let-down godet is ~dju~ted to give the tension between the feed and let-down godet~ that provides the best spinning continuity. These conditions were essentially the came as for st~ndard yarnO Spinning continuity w~s found to be excellent. ~ack~ge~ of the new D~FY were judged ~o be ~t le~st 2s good as ~hose fro~ the standard yarn.
The DTFY ha~ tensile and othelr physac~l properties that nre acceptable for DTFY. ~hese properties are set out and co~pared with ~tandard ~PE~ control DTFY ln ~able lA. ~ecause the new DT~Y ~s spun a~ ~,000 yp~, but has orientation propertie~ (elongation and bire~rin~ence) ~ore like standard POY spun at 3,500 yp~, ~tandard POY
spun ~t e~ch spe2d was prepared and used as control. The crystallinity of the new D~FY ls greater than eithe~
control (density and C.I.).
Each DTFY is textured on a laboratory ~odel, Barmag F~6-900 texturing ~achine, which is equipped for friction ~1~e twist texturing, with as d~sc stack ~
~arm~g ~-6 arrangement, using A O-g-0 array of Kyocera*
ceramic discs with a spacing of 0.75 mm. Texturing speed comparisons are m~de over the speed range fro~ 750 to 1,150 ~p~, incremented in 100 mpm intervals. The dr~w ratao to avoid ~urging for each yarn is determined and used. The temperatures of the ~irst and second heater plates are 60t ae 220~C 3nd 190C, conditions used by ~any in the trade for PET yarns. During texturing, pr~ctically no break~ occurred with the new yarn at any of th~se : speeds. In contrast, there were several break~ for the ~ 30 control yarnc, cspec1ally at highcr speed~, such ~ at _ 950 mp~, more at 1,050 mpm, and neither control would run ; ~t all at 1,150 npm, i.e. ~t was not possible to draw-texture either control yarn at this speed. ~he pre-di~c and the post-di w tensions were ~easured for each yarn at each texeuring cpeed. The textured yarns are ~ te~t~d for textured y~rn properties of broken fila~ents `; * denotes trademark -17-, ` ~ .

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(BFC), and TY~ and CCA crimp properties and Dye Uptake with the results summarized in Table IB.
These results show that the new DTFY has very substantial advantages vs. either control yarn in the very important property of broken filaments ~sFC), especially at the highér texturing speeds of more ~han 1,000 mpm, higher crimp properties ~TYT and CCA), and greater dye uptake.

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TABLE IA
Identification ControlControl New Yarn TMTM (MEQ) 0 0 4.3 Count 250-34-R 235-34-R245-34-R
Spinning Conditions Temperature (C) 293 293 300 Spinneret No. Capillaries 34 34 34 Diversions 15x60 15x6015x60 Spin Speed (YPM) 3500 4000 4000 (MPM) 3200 3660 3660 Spun Yarn Properties Denier 249 235 246 Modulus 23 29 27 Tenacity 2.36 2.67 2.14 Elongation 127 102 134 T(Break) 5.22 5.39 5.02 Birefringence0.0384 0.0506 0.0351 Density 1.3426 1.3452 1.3491 CI 6.5 8.5 12 Interlace (cm) 9 9 9 , :

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E~ o.a3 0.07 O.CB 0.1 o.as 0.~6 0.~7 0.47 0.57 0.~ 1.04 1.03 1.40 5~ Z9 2~ 24 23 17 25 Z5 ~2 a a~ 5.3 4.9 4.6 4.2 2.q 4.6 4.5 4.1 3.9 4.7 4.7 4.2 3.9 79 f 86 70 n 7s 7s 69 n 79 ~5 ~1 ' ~ .`~`
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Table IIB shows that the performance of the DTFY
decreases as the TMTM content is decreased below about 4 MEQ. Example 1 is repeated for items S, X, V and Y, except that the concentration of TMTM is changed as shown in Table IIA. There are no problems in polymer making, polymer transport or spinning, except for item Y, wherein almost 6 MEQ were used, 50 the melt viscosity increased and this caused some problems in spinning. When the TMTM
concentration is increased 61ightly further to 6.3 MEQ, spinning continuity is so poor, with individual filaments pullin~ away from the spinneret, that this either causes the spinning threadline to break or the free end filament ; is recaptured by the threadline and carried to the wind-up. Such free end f~laments are very serious defects, and cause problems in subsequent texturing and, in fabric, give harsh spots. When such fabric is dyed these ~free-ends~ dye deeply and give a very serious and unwanted "spotty" appearance to the fabric. At these higher TMTM contents, filament "fall-out" becomes such a serious problem that spinning is called "Impossible", because of "Melt-Fracture". Changes in spinning conditions, generally used to reduce or eliminate ~Melt ;l Fracture" in PET, did not correct the problem with TMTM
copolymers where the content is about 6.3 MEQ. Similar ~ problems o~ spinning continuity exist at 5.9 MEQ titem Y), j but filaments can be cpun with poor continuity, and so the properties have been measured for item Y.
Each such yarn is textured on a Barmag M-B0, but otherwise as in Example 1. Operability was excellent, even at 1,000 mpm. Each textured yarn was evaluated for textured yarn properties, ~nd compared with controls E and B spun at 3,500 ypm and 4,000 ypm without ~MTM in Table IIB. aroken filaments are much fewer of the TMTM-containing yarns than for the control, but item X
(containing less than 1 ffEQ of TMTM) gave some results of ' ~; :
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borderline acceptability. The TYT crimp properties of these yarns is best understood from the plot of TYT vs.
TMTM content ~MEQ) shown as Figure 2. The preferred concentraticn is about 4 MEQ of TMTM at this withdrawal speed (4,000 ypm).

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~PELE ILA
Identificaticn : Item S Y V X
IMIM (MEQ) 4.0 5.9 2.0 0.8 ~ TMIM (% owP) 0.10 0.15 0.05 0.02 ; Ccunt ~Spun)255-34-R 255-34-R 255-34-R 255-34-R
Spinr m g Con~itions Temçerature 292 292 292 292 Spinneret No capillaries 34 34 34 34 Dimension 15x60 15x60 15x60 l~x60 Spin Speed Spun Yarn Pr erties ~enier 255 253 256 255 Mbdhlus 25 27 25 27 Tenacity 2.30 l.90 2.39 2.57 j Fl ongation 130 137 123 110 T~break) 5.30 4.50 5.33 5.40 Birefringence0.0340 - 0.0400 0.0463 ~` Density 1.3488 1.3508 1.3444 1.3q42 ~` Cl 12 13 8 7.7 ~I~ Interlace (om) 7 7 7 8 ; ~ ~ * Viscosity of yarns 21 ~ 1 W .

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IP~LE IIB
-ITEM MæQ ~ DRA~ RAIIOMæM T9NEIoNs BFC TYI
PR~-DISC PCST-DISC
X 0.8 0.02 1.66 850 107 113 0.25 22 1.66 1000 10~ 129 0.39 20 1.70 lO00 118 137 0.52 19 1.60 1000 79 102 ~0.4B 20 S 4.0 0.10 1.66 850 ~3 88 0.39 27 1.66 1000 B6 93 0.34 24 1.70 1000 92 108 0.09 24 V 2.0 0.05 1.66 850 g7 lt2 0~23 24 1.66 1000 90 llO 0.32 21 1.70 1000 113 126 0.43 20 1.60 1000 74 90 0.40 22 5.9 0.15 1.66 ` 850 ~7 105 0.16 23 1.66 1000 92 109 0.13 21 1.70 1000 107 118 0.23 21 1.60 lO00 80 92 0.36 22 Control O
~4000 ypm) 1.56 ~50 72 ~34 1.13 21 (3660 mpm) 1.56 1000 72 84 1.17 20 1.52 1000 65 82 1.13 1~
1.60 1000 81 96 1.27 20 ECcntrol 0 1.76850 65 77 1.25 21 (3500 yFm) 1.761000 71 B7 2.17 21 ' (3200 mFm) 1.721000 65 88 1.86 15 ~! 1.80lO00 76 90 2.98 21 I

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This Example shows the spinning of the new yarn at a spinning speed of 3,500 ypm (3,200 mpm), in the preferred range, and the change in properties as *he TMTM
content is varied at this spinning speed, followin~
essentially Example 1 in other respe~ts. At this speed of 3,500 ypm (3,200 mpm~, it is found that the concentration of TMTM can be increased to levels of 6.3 MEQ and still obtain feed yarn acceptable for draw texturing. Polymers can be made without 6erious problems at concentrations even hi~her than about 6.3 MEQ, even up to about 8 MEQ.
As the TMTM concsntration increases fro~ 3.9 MEQ to about 6.3 MEQ, the melt viscosity for the required Relative Viscosity increased significantly. The increase is, however, readily compensated for in polymer making and spinning at 3,500 ypm ~ 3,200 mpm) by moderate and acceptable increases in temperature. However, as the TMTM
concentration is increased from about 6.3 MEQ to about ~ MEQ melt viscosity lncreases sharply, for the desired relative viscosity, and I could not compensate for this lncrease in melt viscosity by using higher temperatures in polymer making, polymer transport and especially in spinning. Specifically in spinning, the higher ~elt viscosity sharply increases the melt fracture of the spinning filaments with the accompanying defects in the as-spun yarn and a very sharp increase in the number of spinning breaks. The usual corrective actions of adjusting spinning temperature, varying capillary dimensions and adjusting quench did not overcome the problems, especially at a TMTM concentration of ab~ut 7.9 MEQ and higher.
Table III compares the spinning conditions used and the propérties of the DTFY for the two TMTM-chain branched yarn~ selected for further evaluation and a control without any TM~M. The best spinning temperature found for each poly~er cummarized in the Table. ~he , 1, -26- ~58~

denier of each feed yarn was set during yarn preparation to give approximately 150 denier textured yarn.
Each yarn was textured at texturing ~peeds from 750 mpm to 1,050 mpm, incremen~ed in 100 mpm intervals, on the FK6-900 as in Example l, and the results are summarized in the Table. At the lowest texturing speed, the BFC is not dramatically be~ter for the TMTM chain branched yarn than for ~he con~rol. However, a~ the texturing speed is increased to 850 mpm and above, both 10 TMTM chain branched yarns show a much lo~er ~FC level than the control, which i6 unacceptable. When the two TM~M
chain branched yarns are compared, the higher level of TMTM chain branched yarn is much better in BFC than the lower level. Thus,~it i6 clear that, when making optimum D~FY at these lower withdrawal speeds, one ~ust use more TMTM than is desirable at a higher withdrawal speed ~Example 2). ~t is also clear that more optimization is desirable to obtain a DTFY at this withdrawal speed that will glve less than 0.5 ~FC. In crimp properties of TYT
and CCA, the TM~M crosslinked yarns are also be~ter than the control; these higher yarn crimp properties translate into higher bulk and a more pleasing hand in fabrics.
Again the higher TMTM chain branched yarn has hiqher textured yarn crimp properties than the lower TMTM chain branched. Finally, in dye uptake, both ~M~M chain branched yarns have higher dye uptake than the control and again the higher level of TMTM chain branched yarn has the higher dye uptake. Significantly better dye uniformity is noted at these lower preferred spinning speeds, which are contrary to the preference expressed by MacLean, who had an entirely different objective.
A~ will be appreciate~, for a valid comparison, the operatiny conditions must be comparable. For instance, different results have been obtained with the same DTFY on two texturing machines ~f different types made by the same manufacturer.
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It is well known that better bulk can be obtained, in general, by increasing the temperature of the ~first) heater ~ppropriately during texturing, when using standard linear polymer as D~FY. When using sufficient amounts of chain-brancher according to the inven~ion, I
have obtained similar levels of bulk ~nd dye uniformity (under standard conditions at 265F) at lower texturing ~ temperatures (e.g. about 220C) as I obtained at higher ; texturing temperatures (e.g. about 240C) when using 1~ standard linear polymer ~ DTFY, and then ~ have been able to obtain textured yarn that is improved in these respects by using higher texturing temperatures ~such as about 240C) with the chain-branched DTFY provided sufficient chain-brancher is used according to the present invention.
It is believed that, if trimethyl trimesate is substituted for trimethyl trimellitate in the foregoing Examples, essentially similar results would be obtained.

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I~BLE III
Feed Yarn Identification IMIM (ME~) O 3.9 6.3 IMIM (% OWP) O 0.10 0.16 Count 265-34-R 285-34-R 285-34-R
Spinm ng Ccn~itions - Temperature 2B5C 300C 304C
- Spinneret S~un Yarn ProPerties - Dem er 266 2~4 283 - Mbd~lus 29 23 24 - Tenacity 2.45 2.12 1.96 - Fl ongaticn 124 149 152 - T(break) 5.49 5.2B 4.94 - ~S 57 51 44 - Density 1.3439 1.3429 1.3431 - Cl 7.4 6.5 6.7 - Birefringence - O.0350 0.0316 0.0298 - Pin Cwnt 12 10 10 lexturinq Conlitions TexturiM SPeed ~7~
~FC 0.42 0.48 0.33 CCA 4.2 4.3 4.3 Dye Uptake 111 139 152 Pre-lisc 79 87 89 Post_disc 102 108 110 Draw Ratio 1.71 1.72 1.72 - ~50 mpm BFC 1.1 0.77 0.41 TY~ 25 25 27 CC~ 3.B 3.9 3.B
Dye Uptake 111 139 157 Pre-disc 80 85 84 Fost-disc 104 106 110 Draw Ratio 1.71 1.72 1.72 - 950 mpm ~FC 1.7 0.83 0.54 CCA 3.7 3.7 3.5 Dye UptaXe }05 140 159 Pre-disc B3 90 B6 ~_ Post-disc lOB 109 112 Draw Ratio 1.74 1.72 1.72 - I050 mpm ~FC 1.40 0.84 0.56 CC~ 3.4 3.4 3.2 Dye Uptake 110 141 160 Pre~disc 85 86 79 Post-disc 9B 105 91 Dr~w Ratio 1.79 1.72 1.72

Claims (7)

1. A multifilament draw-texturing feed yarn that has been prepared by polymerizing ethylene and terephthalate derivatives, and by spin-orienting at a withdrawal speed of about 3,000 to 4,000 mpm, and that is improved in that it is capable of being draw-textured at a speed of at least 1,000 mpm to provide a package of textured yarn with not more than about 0.5 BFC, and a TYT of over 20, and by being characterized by the presence of a sufficient amount of trimellitate or trimesate units acting as chain-brancher.

2. A partially oriented polyester multifilament draw-texturing feed yarn of low crystallinity, as shown by a boil-off-shrinkage of about 45% and an elongation to break of about 155%, consisting essentially of polymerized ethylene terephthalate units chain-branched with about 6 MEQ of trimellitate or trimesate units, and of relative viscosity (LRV) about 21.

3. A partially oriented polyester multifilament draw-texturing feed yarn of low crystallinity, as shown by a boil-off-shrinkage of about 20-25% and an elongation to break of about 133%, consisting essentially of polymerized ethylene terephthalate units chain-branched with about 4 MEQ of trimellitate or trimesate units, and of relative viscosity (LRV) about 21.

4. A continuous process for preparing polyester draw-texturing feed yarns, involving the steps of first forming a molten polyester by reaction, in the presence of catalysts therefor, (a) of ethylene glycol with terephthalic acid and/or esters thereof, followed by (b) polycondensation, and then melt-spinning the resulting molten polyester into filaments and withdrawing them at a speed of about 3,000 to 4,000 mpm to provide partially oriented yarns of low crystallinity, wherein the polyester is modified by introducing into the polymer, as a solution in ethylene glycol, trimellitic acid, trimesic acid or an ester of either acid, in a small amount, measured as microequivalents per gram of polymer (MEQ), that depends on the speed (V), in ypm, at which the filaments are withdrawn, the optimum amountsmeasured as MEQ per gram of terephthalate, given by the expression MEQ = 19 -4V, where V is the withdrawal speed in mpm.

5. A process according to claim 4, characterized in that the filaments are withdrawn at a speed of about 3,000-3,200 mpm.

6. A process for preparing a package of false-twist-textured yarn, wherein a multifilament polyester feed yarn is subjected to simultaneous draw-texturing at a speed of at least 500 mpm, the feed yarn consists essentially of polymerized ethylene terephthalate units, chain-branched with trimellitate or trimesate units in such amount that the resulting package of textured yarn has not more than about 0.5 BFC, and over 20 TYT.

7. A process according to claim 6, wherein the texturing speed is at least 850 mpm.