The present invention relates to textured polyester yarn. More particularly, the invention provides a partially oriented poly(trimethylene terephthalate) feed yarn, a continuous draw-texturing process for false-twist texturing of said feed yarn and a textured poly(trimethylene terephthalate) yarn.
The preparation of textured polyester multifilament yarns has been carried out commercially on a worldwide scale for many years. There are numerous well-known texturing processes, which involve crimping, looping, coiling or crinkling continuous filamentary yarns. Such texturing processes are commonly used to impart improved properties in textile yarns such as increased stretch, luxurious bulk and improved hand. In one such process, false-twist texturing, yarn is twisted between two points, heated to a heat-setting temperature, cooled and then allowed to untwist. This process imparts the desired texture because deformation caused by the twist has been set in the yarn.
False-twist texturing of polyester yarns originally employed a pin spindle method and has been generally performed on fully oriented yarn. In more recent years, a friction false-twist method was developed for use with partially oriented yarns. False-twist texturing using the friction method permits considerably higher processing speeds than the pin spindle method. In addition, partially oriented yarns can be drawn and textured in a continuous process thereby reducing operational costs. For these reasons, the friction false-twist method is preferable in the production of textured polyester yarns. Such processes have most commonly been carried out using conventional polyester and polyamide yarns.
More recently, attention has been turned to a wider variety of polyester yarns. In particular, more resources have been allocated to commercializing poly(trimethylene terephthalate) yarns for use in the textile industry. In the prior art, only the older and less efficient pin spindle method has been successful for texturing fully oriented poly(trimethylene terephthalate) yarns. Development of a draw-texturing process for partially oriented poly(trimethylene terephthalate) yarn has been impeded by several factors.
The first factor preventing successful commercialization of a continuous draw-texture process for poly(trimethylene terephthalate) has been the lack of a stable partially oriented yarn. After spinning, a partially oriented yarn is typically wound onto a tube, or package. The yarn packages are then stored or sold for use as a feed yarn in later processing operations such as drawing or draw-texturing. A partially oriented yarn package will not be useable in subsequent drawing or draw-texturing processes if the yarn or the package itself are damaged due to aging of the yarns or other damage caused during warehousing or transportation of the yarn package.
Partially oriented poly(ethylene terephthalate) yarns do not typically age very rapidly, and thus they remain suitable for downstream drawing or draw-texturing operations. Such partially oriented yarns are typically spun at speeds of about 3500 yards per minute (“ypm”) (3200 meters per minute “mpm”). In the past, attempts to make stable partially oriented poly(trimethylene terephthalate) yarns using a spinning speed in this same range have failed. The resulting partially oriented poly(trimethylene terephthalate) yarns have been found to contract up to about 25% as they crystallize with aging over time. In extreme case, the contraction is so great that the tube is physically damaged by the contraction forces of the yarn. In more common cases, the contraction renders the partially oriented poly(trimethylene terephthalate) yarns unfit for use in drawing or draw-texturing operations. In such cases, the package becomes so tightly wound that the yarn easily breaks as it is unwound from the package.
Another factor impeding the development of a commercially viable continuous draw-texturing process in the prior art has been that the proper processing conditions have not been identified. Efforts toward draw-texturing partially oriented poly(trimethylene terephthalate) yarn via a process similar to that used for polyethylene terephthalate have resulted in poor yarn quality, such as too high or too low bulk and/or excessive broken filaments. In addition to the poor yarn quality, the processing performance has been poor due to excessive texturing breaks. Whenever texturing breaks occur, the draw-texturing process comes to a halt as the yarn must be re-strung in the draw-texturing machine. Such processing inefficiencies result in reduced throughput and increased operating cost. Minor changes in the processing conditions for the friction false-twist method have likewise been unsuccessful.
Other efforts to develop a continuous draw-texture process for poly(trimethylene terephthalate) partially oriented yarns have involved lowering the draw ratio to compensate for the twist induced draw and natural contraction upon crystallization and reducing the tensions across the texturing discs to reduce the level of twist insertion. These efforts have not been successful because they have resulted in a much higher denier in the textured yarn, a poor yarn quality, and a lower operating efficiency. To compensate for these problems, adjustments in feed yarn denier must be made to obtain the desired final denier.
There is therefore a need for a stable partially oriented poly(trimethylene terephthalate) yarn and a continuous draw-texturing process for false-twist texturing the partially oriented yarn. Moreover, the need exists for an economical method for false-twist texturing of a poly(trimethylene terephthalate) partially oriented yarn. The present invention provides such a yarn and process.
The present invention comprises a stable partially oriented yarn made from polyester polymer, wherein said polymer comprises at least 85 mole % poly(trimethylene terephthalate) wherein at least 85 mole % of repeating units consist of trimethylene units, and wherein said polymer has an intrinsic viscosity of at least 0.70 dl/g and the partially oriented yarn has an elongation to break of at least 110%.
The present invention further comprises a process for spinning a stable partially oriented yarn, comprising extruding a polyester polymer through a spinneret at a spinning speed less than 2600 mpm and a temperature between about 250° C. and 270° C., wherein said polymer comprises at least 85 mole % poly(trimethylene terephthalate) wherein at least 85 mole % of repeating units consist of trimethylene units, and wherein said polymer has an intrinsic viscosity of at least 0.70 dl/g.
The present invention further comprises a process for continuous draw-texturing a partially oriented yarn made from a polymer substantially comprising poly(trimethylene terephthalate), comprising the steps of:
a is a schematic diagram showing the twist imparted in a twisted yarn.
b is a schematic diagram showing the twist lines as they would look if the yarn is sliced longitudinally along one side and then flattened into a rectangular shape. The figure further shows the twist angle for a twisted yarn as defined herein.
a is a diagram of a friction false-twist spindle used in one embodiment of the present invention.
b is a schematic diagram of the friction discs of the friction false-twist spindle shown in
A stable partially oriented poly(trimethylene terephthalate) yarn has been developed according to the present invention. Furthermore, a process for friction false-twist texturing the stable partially oriented poly(trimethylene terephthalate) yarns has also been developed. The present invention overcomes the problems heretofore experienced with partially oriented poly(trimethylene terephthalate) yarns and processes for friction false-twist texturing such yarns.
To overcome the difficulties encountered when attempting to produce a stable partially oriented poly(trimethylene terephthalate) yarn and a continuous draw-texturing process, one must understand the inherent properties of partially oriented poly(trimethylene terephthalate) yarn, as well the principles of friction false-twist texturing. Applying this understanding, a stable partially oriented poly(trimethylene terephthalate) yarn has been produced and a process for continuous draw-texturing via friction false-twist for partially oriented yarn poly(trimethylene terephthalate) has been developed.
As discussed above, when a partially oriented poly(trimethylene terephthalate) yarn crystallizes, the molecules contract. As partially oriented poly(trimethylene terephthalate) yarn becomes more oriented, total fiber shrinkage is greater upon crystallization. Thus, it has now been found that in order produce a stable partially oriented poly(trimethylene terephthalate) yarn, the yarn must have very low orientation. Orientation of a partially oriented poly(trimethylene terephthalate) yarn is inversely proportional to elongation to break (EB) of the yarn. Thus, a more highly oriented yarn will have a lower EB value. Similarly, a less highly oriented yarn will have a higher EB value.
According to the present invention, a partially oriented poly(trimethylene terephthalate) yarn having an EB of at least 110% is a stable partially oriented poly(trimethylene terephthalate) yarn. In a preferred embodiment, the partially oriented poly(trimethylene terephthalate) yarn has an EB of at least 120%, and most preferably, the EB is at least 130%. This high elongation/low orientation can be achieved by altering the spinning process. For example, the partially oriented yarns according to the invention can be made by spinning partially oriented poly(trimethylene terephthalate) at low spinning speeds, e.g., from about 1650 mpm to 2600 mpm. The spinning temperature may range from about 250° C. to about 270° C.
Further according to the present invention, the partially oriented feed yarn is made from poly(trimethylene terephthalate) having an intrinsic viscosity (“IV”) of at least 0.70 dl/g, more preferably at least 0.90 dl/g, and most preferably, at least 1.0 dl/g. The intrinsic viscosity is measured in 50/50 weight percent methylene chloride/triflouroacetic acid following ASTM D 4603-96.
As illustrated by the examples, only partially oriented poly(trimethylene terephthalate) yarns having an EB of at least 110%, and which are made from polymer having an IV of at least 0.70 dl/g are stable and can be successfully draw-textured according to the process of the present invention.
Conventional friction false-twist texturing methods used for imparting texture to polyethylene terephthalate yarns cannot be successfully employed for the false-twist texturing of poly(trimethylene terephthalate) yarns. This is due, at least in part, to the inherent differences in the physical properties of polyethylene terephthalate and poly(trimethylene terephthalate). For example, poly(trimethylene terephthalate) yarns have higher recoverable elongation and lower tensile modulus than polyethylene terephthalate yarns. Consequently, the use of a conventional friction false-twist texturing process used for polyethylene terephthalate yarns results in excessive filament and yarn breakage, kinking and overdrawing.
It has now been found that, in order to provide an operable draw-texturing process, the final elongation of the textured poly(trimethylene terephthalate) yarn must be at least about 35%, preferably at least about 40%. If the elongation is lower than about 35%, there will be an excessive number of broken filaments and texturing breaks, and the draw-texturing process will not be commercially viable.
It has further been found that the amount of twist force applied during false-twist texturing of partially oriented poly(trimethylene terephthalate) yarns must be carefully controlled to avoid excessive yarn and filament breakage. For yarns of a given stiffuess, the higher the twist force, the greater the level of twist insertion. The yarn is twisted to a level where the torque forces built up in the yarn overcome the frictional forces between the yarn surface and the texturing discs. Thus, the twisting force acts on the yarn until the yarn's stiffness resists further twisting.
Poly(trimethylene terephthalate) yarns are less stiff and therefore less resistant to twisting force than polyethylene terephthalate yarns. In other words, application of the same twisting force to a poly(trimethylene) yarn as is conventionally used for polyethylene terephthalate yarns results in a much higher level of twist insertion.
It has now been found that, in order to achieve a workable process for friction false-twisting of poly(trimethylene terephthalate) yarns, the twisting force should be adjusted such that the level of twist insertion is about 52 to 62 twists per inch, preferably about 57 twists per inch, for a 150 denier yarn. Twist angle provides a method of expressing the level of twist insertion that is independent of the yarn denier. The twist angle of a twisted multifilament yarn is the angle of filaments in relation to a line drawn perpendicular to the twisted yarn shaft as shown in
As Table I illustrates, the twist angle selected depends on the target yarn quality and processing goal. For example, in one application, it may be desirable to have increase bulk, at the expense of processing performance. On the other hand, better processing performance may be chosen over yarn quality. Another factor in determining the twist angle is the denier of the yarn. For example, when draw-texturing very fine denier partially oriented poly(trimethylene terephthalate) yarns (i.e., yarns having a denier per filament of less than 1.5), the twist angle is preferably 46 to 47 degrees. For larger denier yarns, the twist angle is preferably 49 to 50 degrees. In any event, as long as the twist angle is within the range of about 46 to 52 degrees, the false-twist texturing process and yarn quality are acceptable.
The twist angle, α, is the angle between twist line 10 and transverse axis 11, as shown in
where T is the number of twists per inch, and Dy is the diameter of the yarn.
The diameter of a yarn can be approximated from the yarn denier, in microns (10−6 meters), according to equation (II):
Dy≅10.2×√{square root over (Denier)} (II)
Thus, after converting twist per inch to twist per micron, twist angle α can be determined according to equations III or IV, below.
The level of twist insertion is measured by taking a sample of the yarn from the draw-texturing machine during the false-twisting process. The sample can be anywhere from 4 to 10 inches (10 to 25 cm) in length. The sample is obtained using clamps, which are applied to the yarn somewhere between the spindle and the heater. A twist counter is then used to count the number of twists in the sample. The twist angle can then be calculated using equation IV above. The denier used in equations II though IV is the final denier of the textured yarn.
The twisting force, and consequently the level of twist insertion, can be controlled in many ways in a friction false-twist process. For example, the number of working discs can be altered and/or the surface properties of the working discs can be adjusted. If the working discs are of the ceramic variety, the material used, the surface roughness and the coefficient of friction determines the twist force applied by each disc in the false-twist texturing device. For example, a highly polished working surface on the friction disc exerts less twisting force on the yarn than would be exerted by a less polished working disc. If the discs are of the polyurethane variety, the twisting force can be reduced by increasing the hardness, and consequently, the coefficient of friction for the disc surface. Standard polyurethane discs have a Shore D hardness of about 80 to 95. The twisting force can be reduced by using polyurethane discs having a Shore D hardness of more than about 90.
In a preferred embodiment, the false-twist texturing process for poly(trimethylene terephthalate) yarn employs only three or four working discs, as shown in
Further, when making textured poly(trimethylene terephthalate) yarns having a final denier per filament of 2 or higher, the desired twist angle is best achieved by using a 1/3/1 disc configuration, i.e., one entry guide disc, three working discs, and one exit guide disc. When making textured poly(trimethylene terephthalate) yarn having less than 2-denier per filament, a 1/4/1 disc configuration, as shown in
The preferred embodiment of the invention also utilizes a device to isolate the twist between the first delivery roll and the entrance to the heater. The preferred type of twist isolation device is known as a twist stop. As shown in
Thus, yarn 50″ is drawn and textured and has the desired level of cohesion between the filaments as it is fed through fourth feed roll 61 and rolled onto take-up package 62. Take-up speed is defined as the speed, S3, of take-up winder 61, as shown in
Measurements discussed herein were made using conventional U.S. textile units, including denier. The dtex equivalents for denier are provided in parentheses after the actual measured values. Similarly, tenacity and modulus measurements were measured and reported in grams per denier(“gpd”) with the equivalent dN/tex value in parentheses.
The physical properties of the partially oriented poly(trimethylene terephthalate) yarns reported in the following examples were measured using an Instron Corp. tensile tester, model no. 1122. More specifically, elongation to break, EB, and tenacity were measured according to ASTM D-2256.
Boil Off Shrinkage (“BOS”) was determined according to ASTM D 2259 as follows: a weight was suspended from a length of yarn to produce a 0.2 g/d (0.18 dN/tex) load on the yarn and measuring its length, L1. The weight was then removed and the yarn was immersed in boiling water for 30 minutes. The yarn was then removed from the boiling water, centrifuged for about a minute and allowed to cool for about 5 minutes. The cooled yarn is then loaded with the same weight as before. The new length of the yarn, L2, was recorded. The percent shrinkage was then calculated according to equation (V), below:
Dry Heat Shrinkage (“DHS”) was determined according to ASTM D 2259 substantially as described above for BOS. L1 was measured as described, however, instead of being immersed in boiling water, the yarn was placed in an oven at about 160° C. After about 30 minutes, the yarn was removed from the oven and allowed to cool for about 15 minutes before L2 was measured. The percent shrinkage was then calculated according to equation (V), above.
The well-known Leesona Skein Shrinkage test was used to measure bulk of the textured yarns.
Poly(trimethylene terephthalate) polymer was prepared from 1,3-propanediol and dimethylterephthalate in a two-vessel process using tetraisopropyl titanate catalyst, Tyzor® TPT (a registered trademark of E. I. du Pont de Nemours and Company, Wilmington, Del.) at 60 parts per million (“ppm”) (micrograms per gram) by weight, based on finished polymer. Molten dimethylterephthalate was added to 1,3-propanediol and catalyst at 185° C. in a transesterification vessel, and the temperature was increased to 210° C. while methanol was removed. If titanium dioxide was desired, it was added to the process as 20% slurry in 1,3-propanediol. The resulting intermediate was transferred to a polycondensation vessel where the pressure was reduced to one millibar, and the temperature was increased to 255° C. When the desired melt viscosity was reached, the pressure was increased and the polymer was extruded, cooled, and cut into pellets. The pellets were solid-phase polymerized to an intrinsic viscosity of 1.04 dl/g in a tumble dryer operated at 212° C.
Yarn was spun from the poly(trimethylene terephthalate) pellets prepared in Example I using a conventional remelt single screw extrusion process and a conventional polyester fiber melt-spinning (S-wrap) process. The melt-spinning process conditions are given in Table II, below. The polymer was extruded through orifices having a shape and diameter as set forth in Table II. The spin block was maintained at a temperature such as required to give a polymer temperature as set forth in Table II. The filamentary streams leaving the spinneret were quenched with air at 21 ° C., collected into bundles, a spin finish was applied, and the filaments were interlaced and collected. The physical properties of the partially oriented poly(trimethylene terephthalate) yarns were measured using an Instron Corp. tensile tester, model no. 1122, and are set forth in Table III.
As illustrated in Examples III and IV, below, the partially oriented poly(trimethylene terephthalate) yarns made in this example were suitable for subsequent drawing and/or draw-texturing operations. These subsequent operations were not hampered by excessive shrinking due to aging of the partially oriented poly(trimethylene terephthalate) yarns.
This example showed that partially oriented yarns produced according to the present invention are useful in subsequent drawing operations. The example further showed that the yarns are useful as flat yarns, i.e., the yarns in this example were not textured. Partially oriented yarns produced as described in Examples II-A, II-C, II-D and II-E were drawn on a Barmag draw winder, model DW48, with a godet temperature of 130° C. The draw speed, draw ratio, and physical properties of the resulting drawn yarns, as measured on an Instron tensile tester, model 1122, are given in Table IV, below. Partially oriented yarn produced as described in Example II-D was drawn with three different draw ratios, as reported in Table IV.
This example showed that partially oriented yarns produced according to the present invention are useful in subsequent draw-texturing operations. The example further showed the draw-texturing process conditions needed to successfully texture a partially oriented poly(trimethylene terephthalate) yarn using a false-twist texturing process. Using an apparatus as illustrated in
The remaining draw-texturing process conditions and the properties of the resulting draw-textured poly(trimethylene terephthalate) yarns are set forth in Table V, below. In Table V, the draw ratio is given as ratio of the speed of the draw roll to the speed of the feed roll, S2/S1. The tension reported in Table V is as measured at tension monitoring device 63, shown in
The ratio of disc speed to yarn speed reported in Table IV is determined by dividing the surface speed of the friction discs, S4, by the speed, YS, of the yarn as it passes through the twist insertion device. The processing conditions and properties for commercially available polyethylene terephthalate textured yarns are provided for comparison.
1S2/S1;
2S3;
3Entry guide discs/Working discs/Exit guide discs;
4S4,Ys;
5Measured at tension monitor 63
This is a divisional of U.S. patent application Ser. No. 09/795,933, filed Feb. 28, 2001, now U.S. Pat. No. 6,672,047, which is a divisional of U.S. patent application Ser. No. 09/518,732, filed Mar. 3, 2000, now U.S. Pat. No. 6,287,688, both of which are hereby incorporated herein by reference in their entirety.
Number | Name | Date | Kind |
---|---|---|---|
3350871 | Pierce et al. | Nov 1967 | A |
3584103 | Harris | Jun 1971 | A |
3671379 | Evans et al. | Jun 1972 | A |
3681188 | Harris | Aug 1972 | A |
3813868 | Lorenz | Jun 1974 | A |
3816486 | Vail | Jun 1974 | A |
3984600 | Kawase et al. | Oct 1976 | A |
4475300 | Ledenican | Oct 1984 | A |
4475330 | Kimura et al. | Oct 1984 | A |
5250245 | Collins et al. | Oct 1993 | A |
5340909 | Doerr et al. | Aug 1994 | A |
5645782 | Howell et al. | Jul 1997 | A |
5662980 | Howell et al. | Sep 1997 | A |
5782935 | Hirt et al. | Jul 1998 | A |
5885909 | Rudisill et al. | Mar 1999 | A |
5968649 | Aneja | Oct 1999 | A |
6023926 | Flynn | Feb 2000 | A |
6033777 | Best | Mar 2000 | A |
6066714 | Putzig | May 2000 | A |
6071612 | Roderiquez et al. | Jun 2000 | A |
6109015 | Roark et al. | Aug 2000 | A |
6245844 | Kurian | Jun 2001 | B1 |
6255442 | Kurian | Jul 2001 | B1 |
6284370 | Fujimoto et al. | Sep 2001 | B1 |
6287688 | Howell et al. | Sep 2001 | B1 |
6350895 | Kurian | Feb 2002 | B1 |
6353062 | Giardino | Mar 2002 | B1 |
6383632 | Howell | May 2002 | B1 |
6482484 | Brown | Nov 2002 | B1 |
6538076 | Giardino | Mar 2003 | B1 |
6576340 | Sun | Jun 2003 | B1 |
6663806 | Howell | Dec 2003 | B1 |
6672047 | Howell et al. | Jan 2004 | B1 |
6685859 | Howell et al. | Feb 2004 | B1 |
20020116802 | Moerman et al. | Aug 2002 | A1 |
Number | Date | Country |
---|---|---|
0 049 412 | Apr 1985 | EP |
0 745 711 | Dec 1996 | EP |
1 016 741 | Jul 2000 | EP |
1 052 325 | Nov 2000 | EP |
1075689 | Jul 1967 | GB |
1165312 | Sep 1969 | GB |
1254826 | Nov 1971 | GB |
1408094 | Oct 1975 | GB |
49-013457 | Feb 1974 | JP |
52-8123 | Jan 1977 | JP |
52-8124 | Jan 1977 | JP |
57-193534 | Nov 1982 | JP |
58-104216 | Jun 1983 | JP |
5-71013 | Mar 1993 | JP |
8-232117 | Sep 1996 | JP |
8-311177 | Nov 1996 | JP |
9-78373 | Mar 1997 | JP |
11-12824 | Jan 1999 | JP |
11-93026 | Apr 1999 | JP |
11-93031 | Apr 1999 | JP |
11-93036 | Apr 1999 | JP |
11-93037 | Apr 1999 | JP |
11-93038 | Apr 1999 | JP |
11-93049 | Apr 1999 | JP |
11-100721 | Apr 1999 | JP |
11-107036 | Apr 1999 | JP |
11-107038 | Apr 1999 | JP |
11-107081 | Apr 1999 | JP |
11-107154 | Apr 1999 | JP |
11-172526 | Jun 1999 | JP |
11-172536 | Jun 1999 | JP |
11-181626 | Jul 1999 | JP |
11-181650 | Jul 1999 | JP |
11-189920 | Jul 1999 | JP |
11-200143 | Jul 1999 | JP |
11-200175 | Jul 1999 | JP |
11-229276 | Aug 1999 | JP |
2001-020136 | Jan 2001 | JP |
1998-049300(A) | Sep 1998 | KR |
9823662 | Jun 1998 | WO |
9827168 | Jun 1998 | WO |
9939041 | Jan 1999 | WO |
99-11709 | Mar 1999 | WO |
99-11845 | Mar 1999 | WO |
0022210 | Apr 2000 | WO |
00-26301 | May 2000 | WO |
0029653 | May 2000 | WO |
WO 0039374 | Jul 2000 | WO |
WO 0104393 | Jan 2001 | WO |
Number | Date | Country | |
---|---|---|---|
20040134182 A1 | Jul 2004 | US |
Number | Date | Country | |
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Parent | 09795933 | Feb 2001 | US |
Child | 10735462 | US | |
Parent | 09518732 | Mar 2000 | US |
Child | 09795933 | US |