U.S. patent application number 09/898831 was filed with the patent office on 2002-08-29 for soft and stretchable textile fabrics made from polytrimethylene terephthalate.
Invention is credited to Chuah, Hoe Hin, Moerman, Marc.
Application Number | 20020116802 09/898831 |
Document ID | / |
Family ID | 22815156 |
Filed Date | 2002-08-29 |
United States Patent
Application |
20020116802 |
Kind Code |
A1 |
Moerman, Marc ; et
al. |
August 29, 2002 |
Soft and stretchable textile fabrics made from polytrimethylene
terephthalate
Abstract
In this invention, we found unexpectedly that when PTT fiber is
drawn,textured and set under certain conditions, the fabrics made
from textured fibers by this texturing process possess stretch and
hand which is much better than current commercially available PBT
and PET stretch fabrics, and better than PTT textured fibers made
under similar conditions without the setting step. Specifically,
the invention describes the spinning of PTT polymer into yarn with
an elongation of 60 to 160% and draw-texturing the yarn using a
false-twist draw-textured yarn machine at a draw ratio of 1.02 to
1.6 and a yarn temperature of 120 to 160.degree. C., preferably 130
to 150.degree. C. The yarn is further set, usually with a secondary
heater, at a yarn temperature of 70 to 130.degree. C., preferably
85 to 115.degree. C., prior to winding. Then knitted fabrics are
dyed, tentor-set, and finished with fabric softener. This invention
is different from the above teachings in that the PTT yarn is
draw-textured in a false-twist machine. The yarn is crimped
(textured) at a much lower first heater temperature of 130 to
160.degree. C. than described in the above prior art, is set with a
secondary heater at 70 to 130.degree. C. Fabrics made from the set
yarn have as good or better stretch and better hand than fabrics
made from the un-set yarn.
Inventors: |
Moerman, Marc; (Brugge,
BE) ; Chuah, Hoe Hin; (Houston, TX) |
Correspondence
Address: |
Donald F. Haas
Shell Oil Company
Legal - Intellectual Property
P. O. Box 2463
Houston
TX
77252-2463
US
|
Family ID: |
22815156 |
Appl. No.: |
09/898831 |
Filed: |
July 3, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60218447 |
Jul 14, 2000 |
|
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|
Current U.S.
Class: |
28/258 |
Current CPC
Class: |
D02G 1/022 20130101;
D01F 6/62 20130101 |
Class at
Publication: |
28/258 |
International
Class: |
D02G 001/20 |
Claims
We claim:
1. A process of making a stretch fabric with excellent hand from
polytrimethylene terephthalate which comprise: (a) spinning a
polytrimethylene terephthalate polymer into a partially oriented
yarn with elongation of 60 to 150%, (b) draw-texturing the yarn in
a false-twist draw-texturing machine at a draw ratio of 1.02 to
1.6, and a yarn temperature of 120 to 160.degree. C., and (c) heat
setting the draw-textured yarn at a yarn temperature of 70 to
130.degree. C.
2. The process of claim 1 wherein the draw-texturing temperature is
from 130 to 150.degree. C. and the second heat set temperature is
from 85 to 115.degree. C.
3. The process of claim 1 wherein the draw-texturing is carried out
at a draw ratio of from 1.05 to 1.4.
4. A process of making a stretch fabric with excellent hand from
polytrimethylene terephthalate which comprise: (a) spinning a
polytrimethylene terephthalate polymer yarn and drawing it in-situ
using heated godets to a final elongation of 60 to 150%, (b)
draw-texturing the yarn in a false-twist draw-texturing machine at
a draw ratio of 1.02 to 1.6, and a yarn temperature of 120 to
160.degree. C., and (c) heat setting the draw-textured yarn at a
yarn temperature of 70 to 130.degree. C.
5. The process of claim 4 wherein the draw-texturing temperature is
from 130 to 150.degree. C. and the second heat set temperature is
from 85 to 115.degree. C.
6. The process of claim 4 wherein the draw-texturing is carried out
at a draw ratio of from 1.05 to 1.4.
Description
FIELD OF THE INVENTION
[0001] This invention relates to 1,3-propanediol-based polyesters
such as polytrimethylene terephthalate which are used to make
textile fabrics and. More particularly, the invention relates to a
new polytrimethylene terephthalate textile fabrics which exhibit
very good stretch and very good hand.
BACKGROUND OF THE INVENTION
[0002] Stretch and hand are two highly desirable tactile properties
for textile fabrics. Hand is the term used in the textile industry
to describe the tactile qualities of a fabric, e.g., softness,
firmness, elasticity, fineness, resilience, and other qualities
perceived by touch. Stretch fabrics are typically made from (1)
fibers with good elastic recovery such as nylons and polybutylene
terephthalate (PBT), or (2) a mixture of typical nylon or polyester
yarns and an elastic fiber such as the polyurethane elastomer
Spandex. Soft hand derives partly from the intrinsic property of
the polymer such as modulus and also from the yarn and fabric
processing such as setting the yarn during draw-texturing and
mercerizing the fabric with caustic sodium hydroxide solution.
[0003] Therefore, stretch and soft hand can be manipulated to some
extent. However, improvement in one usually is accompanied by a
negative effect on the other. For example, fiber stretch can be
improved by increasing its crimp level or bulk and latent torque
energy during draw-texturing, by increasing the yarn count and
denier per filament (dpf), or by pre-twisting the yarn followed by
texturing. However, the increase in stretch is achieved at the
expense of hand. Higher crimp yarn and higher dpf fabrics feel
coarse and have poorer hand. The most common way to improve the
hand of a draw textured yarn (DTY) is to set the yarn using a
secondary heater at a temperature usually lower than the
temperature at which crimping is carried out (in the first or
primary heater). This secondary heat set treatment turns the yarn
into a set DTY. Although the hand is improved, the secondary
setting process also removes some of the crimp and latent torque
energy resulting in poorer stretch (see Lubos Hes and Petr Ursiny,
Yarn Texturing Technology, Comett Eurotex, 1994 and Ali Demir,
Hassan Mohamed Behery, Synthetic Filament Yarn: Texturing
Technology,Prentice Hall, 1997, on the technology of producing high
extensibility and low extensibility yarns)..
[0004] It is therefore difficult to obtain fibers or fabrics that
have both good stretch and good hand without using elastic fibers
such as Spandex. The only fiber currently that comes close to
achieving the combination of good stretch and hand is PBT
polyester. It is marketed by various fiber companies such as
Hoechst-Celanese as extra stretch performance fiber. However, it is
difficult to set PBT textured yarn because of its low glass
transition temperature.
[0005] PTT fiber is known to have good elastic recovery and soft
hand because of its low modulus. British patent no. 1254826,
Japanese application 09078373, and WO patent application 00/22210
teach the spinning and texturing of PTT yarns for applications in
carpets and stretch fabrics in sportswear, leisure wears, etc. The
texturing of the yarns were done either by air texturing or
false-twist texturing. Japanese application 09078373 teaches
texturing of PTT yarns by manipulating the texturing heater
temperature between 165 and 180.degree. C. such that the textured
yarn has a Young modulus <30 g/den to maintain a soft hand. WO
patent application 00/22210 teaches that PTT fiber with a modulus,
Q, and an elastic recovery, R, such that the ratio of Q/R satisfies
the relationship of 0.18<=Q/R<=0.45, is useful for making
textile fabrics. The Q/R ratio is merely a re-statement of
teachings found in British patent no. 1254826 and Japanese
application 09078373. None of the above references disclose further
setting the textured yarn with a secondary heater.
[0006] They also used modulus as a measure of soft hand. Although
hand is related to yarn modulus it is a much more complicated
tactile property. It encompasses softness without feeling limpy,
drapability, dry touch, and fabric fullness to touch. Although a
robotic instrument (Kawabata Evaluation System) was developed to
measure fabric hand, it has its advantages and drawbacks in
simulating human touch. Therefore, touch by experienced textile
personnel is still widely used to evaluate the hand of fabrics as
in Japanese application 09078373. In this patent application,
example 5 and its comparative example have Young moduli of 21 and
20 g/den., respectively, yet the hand of the example 5 was rated at
7 while the later was rated 5 on a scale of 1 to 8., 8 being the
best and 1 being the worst. This shows that low modulus, although
is a reasonable measure, is inadequate in evaluating hand.
BRIEF SUMMARY OF THE INVENTION
[0007] In this invention, we found unexpectedly that when PTT fiber
is drawn and textured under certain conditions, the fibers and
fabrics made from this texturing process possess stretch and hand
which is much better than current commercially available PBT and
PET stretch fabrics. Specifically, the invention describes the
spinning of PTT polymer into a partially oriented yarn (POY) and
draw-texturing the POY using a false-twist draw-textured yarn
machine at a draw ratio of 1.02 to 1.6, preferably between 1.05 to
1.4, and a yarn temperature of 120 to 160.degree. C., preferably
130 to 150.degree. C. Alternatively, the soft stretch yarn made be
made by spinning a polytrimethylene terephthalate polymer yarn and
drawing it in-situ using heated godets to a final elongation of 60
to 150% at the same temperature. The yarn is further set, usually
with a secondary heater, at a yarn temperature of 70 to 130.degree.
C., preferably 85 to 115.degree. C., prior to winding. Then knitted
fabrics are dyed, tentor-set, and finished with fabric softener.
This invention is different from the above teachings in that the
PTT partially oriented yarn is draw-textured in a false-twist
machine. The yarn is crimped (textured) at a much lower first
heater temperature of 130 to 160.degree. C. than described in the
above prior art.
DETAILED DESCRIPTION OF THE INVENTION
[0008] The polytrimethylene terephthalate polymer is prepared by
the reaction of a molar excess of 1,3-propanediol (PDO) and
terephthalic acid (TPA) (or dimethyl terephthalate) by
esterification followed by polycondensation, with the important
proviso that the reaction conditions include maintenance of
relatively low concentration of PDO and TPA in the melt reaction
mixture.
[0009] As used herein, "1,3-propanediol-based aromatic polyester"
refers to a polyester prepared by the condensation polymerization
reaction of one or more diols with one or more aromatic diacids or
alkyl esters thereof (herein referred to collectively as "diacid")
in which at least 80 mole percent of the diol(s) is
1,3-propanediol. "Polytrimethylene terephthalate" refers to such a
polyester in which at least about 80 mole percent of the diacid(s)
is terephthalic acid. Other diols which may be copolymerized in
such a polyester include, for example, ethylene glycol, diethylene
glycol, 1,4-cyclohexane dimethanol, and 1,4-butanediol; and other
aromatic and aliphatic acids which may be copolymerized include,
for example, isophthalic acid and 2,6-naphthalane dicarboxylic
acid.
[0010] The preparation of the invention composition can be
conveniently described by reference to an esterification step, a
prepolymerization step, and a polycondensation step. The process
can be carried out in batch or continuous mode. Each step can be
carried out in multiple stages in a series of reaction vessels if
desired for optimum efficiency in the continuous mode or for
product quality. Each step is preferably carried out in the absence
of oxygen. The following will describe the process in terms of the
preferred continuous mode.
[0011] An esterification catalyst is optional but preferred in an
amount of about 5 ppm to about 100 ppm (metal), preferably about 5
ppm to about 50 ppm, based on the weight of final polymer. Because
of the desirable lower temperatures under which the esterification
is carried out, the esterification catalyst will be of relatively
high activity and resistant to deactivation by the water byproduct
of this step. The currently preferred catalysts for the
esterification step are titanium and zirconium compounds. The
currently preferred catalyst for esterification, prepolymerization,
and polycondensation is titanium tetrabutoxide. The catalyst is
preferably formulated and added to the monomer feed, prior to or
during the esterification, as a dilute liquid solution in
1,3-propanediol. This catalyst feed will preferably contain 5 wt %
or less titanium.
[0012] The invention 1,3-propanediol-based aromatic polyester
prepared by the invention process has an intrinsic viscosity (IV)
of at least 0.6, preferably 0.7 or greater, most preferably 0.8 or
greater, and for some applications, preferably within the range of
about 0.9 to about 1.3, as measured in a solution of 0.4 g polymer
in 100 ml of a 60:40 solution of phenol:tetrachloroethane at
30.degree. C. (or as a dilute solution in another solvent such as
hexafluoroisopropanol, and converted by known correlation to the
corresponding IV in 60:40 phenol:tetrachloroethane).
[0013] The first step of the process of the present invention is
spinning the PTT polymer into a partially oriented yarn (POY) with
an elongation at break of <160% by varying the winder take-up
speed between 1,000 and 4,500 m/min.. Alternatively, the extruded
filament bundle can be cooled and then drawn between a set of
heated godets to a final elongation of 60 to 150%. The yarn is then
wound into appropriate packages.
[0014] Yarn made with either one of the above methods is then
draw-textured in a false-twist draw-texturing machine at a draw
ratio of 1.02 to 1.6, preferably 1.05 to 1.4. The false-twist
method is preferred for texturing into high elastic yarn for
stretch fabrics because it gives higher twist density, high crimp,
and latent torque energy needed for stretch yarn compared to other
texturing methods such as edge-crimping and stuffer box crimping.
The false-twist method is a continuous method for producing
textured yarns which utilizes simultaneous drawing, twisting, heat
setting, and untwisting. The yarn is taken from the supply package
and fed at controlled tension through the heating unit, through a
false-twist spindle or over a friction surface that is typically a
stack of rotating discs called an aggregate or crossed friction
belts, through a set of take-up rolls, and onto a take-up package.
The twist is set into the yarn by the action of the heater tube and
subsequently removed above the spindle or aggregate resulting in a
group of filaments with the potential to form helical springs.
[0015] The yarn is heated to a temperature of 120 to 160.degree.
C., preferably 130 to 150.degree. C. The goal is to make the yarn
soft for drawing and twisting. If a contact heater is used, then
the heater may be operated at the above temperature range. However,
if a non-contact heater is used, then the heater may be operated at
a higher temperature of 180 to 260.degree. C., preferably 200 to
240.degree. C.
[0016] The draw-textured yarn (DTY) is then subjected to a second
heat set treatment before it is wound and further processed. The
second heater is often part of the DTY machine but a separate
heater may also be used. The second heat set is done at a lower
temperature than the first heater by about 35.degree. C. Thus the
yarn is set in the second heater at 70 to 130.degree. C.,
preferably 85 to 115.degree. C. If a contact heater is used, it may
be operated at this temperature range. If a non-contact heater is
used, it should be operated at an appropriately higher temperature
of 120 to 200, preferably between 140 to 180.degree. C.
[0017] To finish the yarn and make a fabric, the standard steps of
knitting, dyeing of fabric with disperse dyes at 100 to 110.degree.
C. without using a carrier, setting the fabric in a tentor frame
with overfeed at 130 to 170.degree. C., and finishing with a
softener may be used. Some of the stretch of the yarn is lost
during the finishing but when the above proper finishing parameters
are used, the final fabric has good stretch and has very good hand.
This is quite surprising since the conventional wisdom is that a
second heat set will destroy the stretch of a polyester fabric.
EXAMPLES
Example 1
[0018] PTT Fiber Extrusion Using a SDY Machine:
[0019] PTT chips (IV=0.92 dl/g) were dried in a close-loop hot air
dryer at 130.degree. C. to a final moisture level of <30 ppm.
They were extruded at 254.degree. C. into 8-end 90 denier/24
filament yarns by first cooling the filament bundles in a quench
cabinet. 0.6% Delion HKS-19 (supplied by Takemoto Oil) spin finish
was applied to the filament bundles prior to wrapping on a
54.degree. C. heated godet at 2,500 m/min. The yarns were drawn
with a draw ratio of 1.43 between this first heated godet and a
second set of godet at 80.degree. C. and at a speed of 3,580 m/min.
They were then wound at 3,410 m/min. into 9-kg packages.
1 Yarn Properties: Denier 84.6 Tenacity 3.13 g/den. Elongation 65%
Boiling Water Shrinkage 9.2% Uster 1.2%
[0020] Draw-Texturing:
[0021] The yarns were draw-textured using a Teijin Seikki 15M
friction-disc type false-twist machine with non-contact heaters for
both the first heater and the second heater.
2 Texturing Conditions: Yarn Speed 650 m/min. Draw Ratio 1.15 D/Y
Ratio 2.25 OF2 2.0 OF3 4.5 First Heater: Short/Long 200/210.degree.
C. Sections Second Heater 160.degree. C. Disc 9 mm PU disc in 1-6-1
Configuration
[0022]
3 Textured Yarn Properties: Denier 81.5 Elongation 42% Crimp
Contraction 49.0% BWS 10.0%
[0023] Knitting:
[0024] The textured-set DTY yarn was knitted with interlock
circular knitting at 22 rpm using a 96- feeder, 36-inch and
24-gauge machine. The fabric weight was 230 g/yd.
[0025] Dyeing and Finishing:
[0026] The knitted fabric was dyed using disperse dye into navy
blue color at atmospheric boil for 30 minutes. The fabric width
before dyeing was 174 cm, and was 150.4 cm after dyeing. It was
further set at 150.degree. C. for 2 minutes in tentor frame and
finished with a silicone-based softener. The final fabric width was
140.2%. Shrinkage from dyed to finished fabric was 19.4%.
[0027] Fabric Properties:
[0028] The finished fabrics had excellent hand, stretch, and
recovery. This tactile property is evaluated based on touch by
five-experienced textile engineers as being exceptional.
[0029] Morphology of Fabric:
[0030] The course and wale directions of the final fabric are
skewed at an angle to each other instead of perpendicular to each
other. There is also an out-of-plane twist of the knitted loops in
the course direction. The degree of skewed angle and out-of-plane
twisting of loops were dependent on the amount of crimp input from
false-twisting and degree of set with second heater. The relatively
ordered loop structures after dyeing and finishing also contributed
to the overall excellent hand and stretch of the fabric.
Example 2
[0031] PTT Fiber Extrusion to POY Using Conventional Machine
Without Heated Godet:
[0032] PTT chips (IV=0.92 dl/g) were dried in a close-loop hot air
dryer at 130.degree. C. to a final moisture level of <30 ppm.
They were extruded at 258.degree. C. into 4-end 130 denier/24
filament yarns by first cooling the filament bundles in a quench
cabinet. 0.5% Lurol 7089 (supplied by Goulston) spin finish was
applied to the filament bundles. Via a Duo godet the yarn was wound
on a Barmag SW winder at a speed of 2800 m/min into 10 Kg
packages.
4 POY Properties: Denier 130 Tenacity 2.2 g/den. Elongation 110%
Uster 1.1%
[0033] False-twist-Texturing:
[0034] The yarns were draw-textured using a Barmag AFK disc type
DTY machine.
5 (1) HE (high extensibility) yarn: Texturing Conditions Yarn Speed
600 m/min. Draw Ratio 1.52 D/Y Ratio 1.8 First Heater: Short/Long
240/220.degree. C. Sections Disc 9 mm PU disc in 1-4-1
Configuration Second Heater (short) Off
[0035]
6 Textured HF Yarn Properties: denier/fil 89/24 Tenacity g/den.
3.05 Elongation % 35 Crimp contraction % 48 Crimp modulus % 33
Crimp stability % 90
[0036]
7 2) Low Extensibility Set yarn: Texturing Conditions Yarn Speed
600 m/min. Draw Ratio 1.52 D/Y Ratio 1.8 First Heater: Short/Long
240/220.degree. C. Sections Disc 9 mm PU disc in 1-4-1
Configuration Second Heater (short) 160.degree. C.
[0037]
8 Textured Set Yarn Properties: Den./fil 100/24 Tenacity g/den 3.74
Elongation % 47 Crimp contraction % 24 Crimp modulus % 9 Crimp
stability % 77
[0038] Knitting:
[0039] The textured HE and set yarn were knitted with interlock
circular knits at 22 rpm using a 96-feeder, 36-inch and 28-gauge
machine. The fabric weights were kept constant at 260 kg/m2 by
adjusting the stitch length since the low extensibility set yarn
has a slightly higher denier than the high extensibility yarn.
[0040] Dyeing and Finishing:
[0041] The knitted fabrics were dyed using disperse dye into purple
color at atmospheric boil for 30 minutes. Both fabrics were further
set at 150.degree. C. for 30 seconds on a tentor frame, and
finished with a silicone-based softener (Ultratex ex
Ciba-Geigy).
[0042] Fabric Properties:
[0043] The properties of both HE-based and set-based yarn are given
in the table below. The hand (tactile property) is evaluated based
on touch by five-experienced textile engineers. An independent
textile laboratory (ITF, France) measured elastic performance.
9 high extensibility yarn-based set yarn-based interlock interlock
property fabric fabric 2X hysteresis cycle Stitch length (cm/100
st.) 24.4 25.2 Stitch density (st/cm.sup.2) 486 464 fabric weight
Kg/m2 260 260 width E% at 10N 98 136 (length E% at 10N) 35 35
Elastic recovery 90 93 (.DELTA.1.sub.0 -
.DELTA.1.sub.1)/.DELTA.1.sub.0 .times. 100% Permanent deformation %
2 2.2 Touch/Handle good superior
[0044] Unexpected Results:
[0045] Unexpectedly, the knitted fabric of example 1 using set
false-twist textured yarn gave a fabric with a combination of good
stretch and hand.
[0046] In Example 2, false-twist texturing was done with a
controlled un-set high extensibility PTT yarn. As expected from
teachings of false-twist texturing technology such as by Lubos Hes
and Petr Ursiny, and Demir and Behery, the crimp contraction of PTT
textured yarn decreased from 48% (high extensibility DTY) to 24%
(low extensibility DTY) when it was set with a secondary heater.
However, we were surprised to find that the set yarn knitted fabric
had a higher stretch of 136% in the width direction than the 98%
stretch of the high extensibility yarn fabric. The stretch in the
length direction remained the same for the two fabrics. The elastic
recovery and permanent deformation of the two fabrics were
essentially similar at about 90% and 2% respectively. What was more
surprising was the hand of the set yarn fabric was superior than
that of the un-set high extensibility yarn fabric. These results
were totally unexpected since current false-twist technology
teaches that hand can only be improved at the expense of
stretch.
* * * * *