Note: Descriptions are shown in the official language in which they were submitted.
~95~
--1--
TIT1E
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
.
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
.~ .
2q5 --1--
::
:~
~, ' ' ~ :
, - '
~958(~
--2--
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
:
~ -2-
~9~
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
-3-
: ,:
:,
::
.' ,. . ~ . .
~2g~
--4--
~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.
-d-
:''
.
3L Z 9 ~
- 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.
_5_
:, ~
.,
- -6- ~ Z ~
DESCRIPTION OF THE PREFERRED EM90DIMENTS
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
: :
: -6-
j: : :
' ~ : :
: :
.
..... .
~%~
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
-7-
-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
-8-
.
,
. , .
-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
:,:: :
_g_
::;
. ; :
:,
'
,
-lo- ~.2~5~Q
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
--10--
,
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.
: `
--1 1--
-12~ 35~
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.
-12-
.
-13- ~2~
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~,
.
-13-
:
:,
.. . . . .
. ..
,' ' ~ " ~ ' ' , :
-
~ '.
-14~ g~
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.
EXAMPLE 1
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-
.. . .
`' ` :
.
` `
L29~
-16-
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
,:
-16-
.
~' '
.
,~, . . .
-17~
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-
,
` ~ .
,
~..~,., i, ,, ~
~2~5~
-18-
(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.
. ~ ,
~'
~ ~ .
, ~
18-
:
~ .
~ .
-19-
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
BOS 61 51 22
Birefringence0.0384 0.0506 0.0351
Density 1.3426 1.3452 1.3491
CI 6.5 8.5 12
Interlace (cm) 9 9 9
,
:
'
:
:
~' :
19-
. ~
~.
. "~ . . .
:
5'~63
--20--
~E IB
lMlM 1~ 4.3 0 ~ O
_
E~gOO
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
' ~ .`~`
:: ~
`:
~ ~ -20-
'~ ~
` ~: ` ` :
-21- ~9~-~
EXAMPLE 2
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
-21-
'
~; :
~, . . .
129~
-22-
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).
~'
~ 30
`: :
, ~: :
22-
~,
,,
~ ~:
:; :
~'
, ~ :
.
~2~5~`i[31~
-23-
~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
YFM 4000 4000 4000 4000
MPM 3660 3660 3660 3660
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
EOS 21 16 2B 48
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 .
.
:, :
:::
23-
::`
, .
' - .
-24-
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
,
:~
:: : :
:
, : : :
~ 24_
:
~ :
.
.
. : :.~ .
12~il30~
-25-
EXAMPLE 3
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
-25-
,
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.
.
~ -26-
.
.
-27- ~ ~ 9 ~3~ ~
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.
; 25
;
,:
~ -27-
~Z9~
-28-
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
TYT 27 27 29
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
TYT 22 24 25
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
TYT 21 22 23
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
-28-
