PARTIALLY ORIENTED POLY(TRIMETHYLENE TEREPHTHALATE) YARN

Abstract: A partially oriented yarn made from a 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%. In addition, processes for spinning a partially oriented yarn and for continuous draw-texturing a partially oriented feed yarn.

Description: TITLE OF INVENTION PARTIALLY ORIENTED POLY(TRIMETHYLENE TEREPHTHALATE) YARN FIELD OF THE INVENTION The present invention relates to textured polyester yam. More particularly, the invention provides a partially oriented poly(trimethylene terephthalate) feed yam, a continuous draw-texturing process for false-twist texturing of said feed yam and a textured poly(trimethylene terephthalate) yam. BACKGROUND OF THE INVENTION The preparation of textured polyester multifilament yams 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 yams. Such texturing processes are commonly used to impart improved properties in textile yams such as increased stretch, luxurious bulk and improved hand. In one such process, false-twist texturing, yam 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 yam. False-twist texturing of polyester yams originally employed a pin spindle method and has been generally performed on fully oriented yam. In more recent years, a friction false-twist method was developed for use with partially oriented yams. False-twist texturing using the friction method permits considerably higher processing speeds than the pin spindle method. In addition, partially oriented yams 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 yams. Such processes have most commonly been carried out using conventional polyester and polyamide yams. More recently, attention has been turned to a wider variety of polyester yams. In particular, more resources have been allocated to commercializing poly(trimethylene terephthalate) yams 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) yams. 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 yam. After spinning, a partially oriented yam is typically wound onto a tube, or package. The yam packages are then stored or sold for use as a feed yam in later processing operations such as drawing or draw- texturing. A partially oriented yam package will not be useable in subsequent drawing or draw-texturing processes if the yam or the package itself are damaged due to aging of the yams or other damage caused during warehousing or transportation of the yam package. Partially oriented poly(ethylene terephthalate) yams do not typically age very rapidly, and thus they remain suitable for downstream drawing or draw- texturing operations. Such partially oriented yams 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) yams using a spinning speed in this same range have failed. The resulting partially oriented poly(trimethylene terephthalate) yams 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 yam. In more common cases, the contraction renders the partially oriented poly(trimethylene terephthalate) yams unfit for use in drawing or draw-texturing operations. In such cases, the package becomes so tightly wound that the yam 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 yam quality, such as too high or too low bulk and/or excessive broken filaments. In addition to the poor yam 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 yam 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 yams 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 yam, a poor yam quality, and a lower operating efficiency. To compensate for these problems, adjustments in feed yam denier must be made to obtain the desired final denier. There is therefore a need for a stable partially oriented poly(trimethylene terephthalate) yam and a continuous draw-texturing process for false-twist texturing the partially oriented yam. Moreover, the need exists for an economical method for false-twist texturing of a poly(trimethylene terephthalate) partially oriented yam. The present invention provides such a yam and process. SUMMARY OF THE INVENTION The invention is directed to a partially oriented yam made from a 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 yam has an elongation to break of at least 1 10%. In addition, the invention is directed to a process for spinning a partially oriented yam, 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. Preferably the spinning speed is between 1650 mpm and 2300 mpm. The invention is also directed to a process for continuous draw- texturing a partially oriented feed yam made from a polymer substantially comprising poly(trimefhylene terephthalate), comprising the steps of: (a) feeding a partially oriented feed yam through a heater, wherein the heater is set to a temperature between about 160°C and 200°C; (b) feeding the heated yam to a twist insertion device, whereby the yam is twisted such that in a region between the twist insertion device and up to and including the heater, the yam has a twist angle of about 46 degrees to about 52 degrees; and (c) winding the yam on a winder. The invention is further directed to a draw textured yam made by continuous draw-texturing a partially oriented yam with the following steps: (a) feeding the partially oriented yarn described above through a heater, wherein the heater is set to a temperature between about 160°C and 200°C; (b) feeding the yam to a twist insertion device, whereby the yam is twisted such that in a region between the twist insertion device and up to and including the heater, the yarn has a twist angle of about 46 degrees to about 52 degrees; and (c) winding the yam on a winder. Preferably the twist insertion device is a friction spindle, such as disc type. Preferably the friction spindle comprises at least one entry guide disc, three to five working discs, and one exit guide disc. More preferably the friction spindle comprises working discs spaced apart by about 0.75 to 1.0 mm. In another preferred embodiment, the twist insertion device is a cross belt. Preferably prior to step (a), the yam is passed through a twist isolation device. Preferably, the 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 elongation to break is preferably at least 120% and more preferably at least 130%. The elongation to break can be up to 180% or higher. Generally is will be up to 160%, or up to up to 145%). The intrinsic viscosity is preferably at least 0.90 dl/g, and more preferably at least 1.0 dl/g. DESCRIPTION OF THE DRAWINGS Figure la is a schematic diagram showing the twist imparted in a twisted yam. Figure lb is a schematic diagram showing the twist lines as they would look if the yam is sliced longitudinally along one side and then flattened into a rectangular shape. The figure further shows the twist angle for a twisted yam as defined herein. Figure 2a is a diagram of a friction false-twist spindle used in one embodiment of the present invention. Figure 2b is a schematic diagram of the friction discs of the friction false-twist spindle shown in Figure 2a. Figure 3 is a diagram of a friction false-twist spindle used in the prior art for a polyethylene terephthalate false-twist process. Figure 4 is a schematic diagram of a twist stop device used in an embodiment of the present invention. Figure 5 is a schematic diagram of the friction false-twist process of the present invention. DETAILED DESCRIPTION OF THE INVENTION A stable partially oriented poly(trimethylene terephthalate) yam has been developed according to the present invention. Furthermore, a process for friction false-twist texturing the partially oriented poly(trimethylene terephthalate) yams has also been developed. The present invention overcomes the problems heretofore experienced with partially oriented poly(trimethylene terephthalate) yams and processes for friction false-twist texturing such yams. To overcome the difficulties encountered when attempting to produce a stable partially oriented poly(trimethylene terephthalate) yam and a continuous draw-texturing process, one must understand the inherent properties of partially oriented poly(trimethylene terephthalate) yam, as well the principles of friction false-twist texturing. Applying this understanding, a stable partially oriented poly(trimethylene terephthalate) yam has been produced and a process for continuous draw-texturing via friction false-twist for partially oriented yam 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) yam 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) yam, the yam must have very low orientation. Orientation of a partially oriented poly(trimethylene terephthalate) yam is inversely proportional to elongation to break (E B ) of the yarn. Thus, a more highly oriented yam will have a lower E B value. Similarly, a less highly oriented yam will have a higher E B value. According to the present invention, a partially oriented poly(trimethylene terephthalate) yarn having an E B of at least 110% is a stable partially oriented poly(trimethylene terephthalate) yam. That is, with such a partially oriented yam physical properties are substantially uniform and are substantially maintained over time. In a preferred embodiment, the partially oriented poly(trimethylene terephthalate) yam has an E B of at least 120%), and most preferably, the E B is at least 130%o. E B is generally up to 180%), preferably up to 160%), even more preferably up to 145% and most preferably up to 137.1%). This high elongation/low orientation can be achieved by altering the spinning process. For example, the partially oriented yams 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 yam 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. Intrinsic viscosity is preferably no more than 1.5 dl/g, more preferably no more than 1.2 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) yams having an E B 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 yams cannot be successfully employed for the false-twist texturing of poly(trimethylene terephthalate) yams. 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) yams have higher recoverable elongation and lower tensile modulus than polyethylene terephthalate yams. Consequently, the use of a conventional friction false-twist texturing process used for polyethylene terephthalate yams 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. The elongation may be up to 55% or higher. 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 yam and filament breakage. For yarns of a given stiffness, the higher the twist force, the greater the level of twist insertion. The yam is twisted to a level where the torque forces built up in the yam overcome the frictional forces between the yam surface and the texturing discs. Thus, the twisting force acts on the yam until the yam's stiffness resists further twisting. Poly(trimethylene terephthalate) yams are less stiff and therefore less resistant to twisting force than polyethylene terephthalate yams. In other words, application of the same twisting force to a poly(trimethylene) yam as is conventionally used for polyethylene terephthalate yams 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 yam. 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 yam is the angle of filaments in relation to a line drawn perpendicular to the twisted yam shaft as shown in Figure 1. According to the process of the invention, the twist angle should be about 46 to about 52 degrees. If the twist angle is less than about 46 degrees, the partially oriented poly(trimethylene terephthalate) yam will have poor processing performance and cannot be textured because of excessive texturing breaks. Additionally, the textured yam will have poor quality because of excessive bulk. If the twist angle is more than about 52 degrees, the partially oriented poly(trimethylene terephthalate) yam will have good processing performance, but very poor yam quality because of low bulk and excessive broken filaments. However, by maintaining the twist angle at about 46 to 52 degrees, the processing performance results in an acceptable level of texturing breaks while producing the desired yam quality. Table I, below, summarizes the yam quality and processing performance experienced for a range of twist angles. Table I Twist TPI (70 TPI (150 ___ = ______ = ___ Angle, ° Den.) Den.) Yarn Quality Process Performance 46.8 89.0 60.8 Some tight spots, Higher texturing breaks higher bulk 49.2 81.8 55.9 Good bulk, low broken Lower texturing breaks filaments 51.8 74.5 50.9 Lower bulk and higher Least texturing breaks broken filaments 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 yam. For example, when draw-texturing very fine denier partially oriented poly(trimethylene terephthalate) yams (i.e., yams having a denier per filament of less than 1.5), the twist angle is preferably 46 to 47 degrees. For larger denier yams, 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 yam quality are acceptable. The twist angle, α, is the angle between twist line 10 and transverse axis 11, as shown in Figure lb. Figure la shows a schematic view of a twisted yam. Twist line 10 represents the twist in the yam. Figure lb shows the yam laid out flat if split along longitudinal line 12 (shown in Figure la). Lines 12L and 12R represent the left and right side, respectively, of the laid out yam. Larger angles correspond to lower levels of twist insertion. From the geometry of the twist and the properties of the yam, as shown in Figure lb, the relationship between twist angle, yarn denier, and the number of twists per inch is given by equation I, below: 1 / T (I) Tan(α) = , where T is the number of twists per inch, π x D y and D y is the diameter of the yam. The diameter of a yam can be approximated from the yarn denier, in microns (10 "6 meters), according to equation (II): (II) D y ≤ 10.2 x VDenier Thus, after converting twist per inch to twist per micron, twist angle α can be determined according to equations III or IV, below. m τ ( , (2.54 χ l0 4 /τ) 2.49χ l0 3 (III) Tan(α) = — * = π x 10.2 x VDenier π x T x VDenier The level of twist insertion is measured by taking a sample of the yam 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 yam 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 yam. 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 yam 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) yam employs only three or four working discs, as shown in Figures 2a and 2b. Working discs 20, 21, 22, and 23 are mounted on parallel axles 24, 25, 26. Entry guide disc 27 and exit guide disc 28 serve to guide the yam into the false-twisting apparatus and do not impose twisting force on the yam. In a more preferred embodiment, the spacing between discs, S, is about 0.75 to 1.0 mm, as shown in Figure 2a. In contrast, a conventional process for false-twist texturing of polyethylene terephthalate yams typically employs five to seven working discs which are spaced apart by about 0.5 mm, as shown in Figure J . Further, when making textured poly(trimethylene terephthalate) yams 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 Figure 2a, best achieves the desired result. 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 Figure 4, the preferred twist stop consists of two circular rims 41 and 42 spaced apart from one another and having a series of spokes or ribs 43. The yam is woven through the spokes 43. Such twist stop devices may be obtained from textile machine suppliers such as Eldon Specialties, Inc., Graham, NC. Figure 5 is a schematic diagram showing an apparatus useful in carrying out a preferred embodiment of the friction false-twist process of the invention. Partially oriented yam 50 is fed from creel supply 51 through the first feed roll 52. From feed roll 52, the partially oriented yam 50 is threaded through twist stop 53, as described above. As shown in Figure 5, the yam is twisted between twist stop 53 and twist insertion device 54. Twisted yam 50' passes through heater 55 which is set to a heat setting temperature of about 160°C to about 200°C, preferably about 180°C. Twisted yam 50' is then passed through cooling plate 56 which is adjacent to heater 55, as shown in Figure 5. As yam 50' passes over cooling plate 56, it is cooled to a temperature substantially lower than the heat setting temperature in order to heat set the twist in the yam. From twist insertion device 54, the yam is fed into second roll 57 as shown in Figure 5. The speed of second feed roll 57, S 2 , and the speed of first feed roll 52, Si, determine the draw ratio, which is defined as the ratio: S /Sι. Because the present example employs a false-twist process, the yarn loses the twist inserted by twist insertion device 54 as it exits that device. However, the yam retains the texture imparted by the false-twist process. Drawn and textured yam 50" passes from second feed roll 57 to third feed roll 58. Interlace jet 59, located between second feed roll 57 and third feed roll 58, is used to increase cohesion between the filaments. Second heater 60 is normally used to post heat set the yam, but in texturing poly(trimethylene terephthalate) yams for maximum stretch it is turned off. Thus, yam 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, S 3 , of take-up winder 61, as shown in Figure 5. In a preferred embodiment, twist insertion device 54 is a friction spindle comprising parallel axles and friction discs as described above. In another embodiment, the twist insertion device is a cross belt. The yams of this invention can have round, oval, octa-lobal, tri-lobal, scalloped oval, and other shapes, with round being most common. 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. TEST METHODS The physical properties of the partially oriented poly(trimethylene terephthalate) yams reported in the following examples were measured using an Instron Corp. tensile tester, model no. 1122. More specifically, elongation to break, E B , 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 yam to produce a 0.2 g/d (0.18 dN/tex) load on the yam and measuring its length, The weight was then removed and the yam was immersed in boiling water for 30 minutes. The yam was then removed from the boiling water, centrifuged for about a minute and allowed to cool for about 5 minutes. The cooled yam is then loaded with the same weight as before. The new length of the yam, L 2 , was recorded. The percent shrinkage was then calculated according to equation (V), below: (V) Shrinkage (%) = l x 100 Dry Heat Shrinkage ("DHS") was determined according to ASTM D 2259 substantially as described above for BOS. Li was measured as described, however, instead of being immersed in boiling water, the yam was placed in an oven at about 160°C. After about 30 minutes, the yam was removed from the oven and allowed to cool for about 15 minutes before L 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 yams. EXAMPLES Example I - Polymer Preparation Poly(trimethylene terephthalate) polymer was prepared from 1 ,3- propanediol and dime hylterephthalate in a two-vessel process using tetraisopropyl titanate catalyst, Tyzor® TPT (a registered trademark of E. I. du Pont de Nemours and Company, Wilmington, DE) 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. Titanium dioxide was added to the process as 20%> slurry in 1,3-propanediol to give 0.3 weight % TiO in the polymer. 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. Example II - Partially Oriented Yarn Preparation Yam 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) yams were measured using an Instron Corp. tensile tester, model no. 1 122, and are set forth in Table III. Table II Ex. Cross- Orifice Polymer # of Spin Feed Winding section Dia. Temp, Filaments Finish Roll Speed (mm) °C (wt.%) Speed (mpm) (mpm) II-A Round 0.38 265 34 0.5 2286 2307 II-B Octa-lobal ~ 260 50 0.5 2103 2106 II-C Round 0.38 255 34 0.4 2103 21 19 II-D Round 0.23 254 100 0.6 1829 1808 II-E Round 0.23 254 200 0.6 1796 1767 II-F Round 0.32 260 68 0.5 1920 1915 Table III Ex. E B , % POY Denier (dtex) Tenacity, g/d Modulus, g/d BOS, % (dN/tex) (dN/tex) II-A 131.6 226(251) 2.13(1.88) 19.0(16.8) 53.8 II-B 130.7 227(252) 2.06(1.82) 20.7(18.3) 56.2 II-C 130.3 105(117) 2.32(2.05) 19.6(17.3) 52.1 II-D 128.1 107(119) 2.47(2.18) 18.6(16.4) 52.4 II-E 137.1 226(251) 2.33(2.06) 18.0(15.9) 53.3 II-F 127.5 113(125) 2.34(2.07) 19.2(16.9) ~ As illustrated in Examples III and IV, below, the partially oriented poly(trimethylene terephthalate) yams 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) yams. Example HI - Single End Drawing This example showed that partially oriented yams produced according to the present invention are useful in subsequent drawing operations. The example further showed that the yams are useful as flat yams, Le., the yams in this example were not textured. Partially oriented yams 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 yams, 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. Table IV Ex. Draw Draw Denier Tenacity, g/d EB? Modulus, g/d BOS, Speed Ratio (dtex) (dN/tex) % (dN/tex) % (mpm) III-A 400 1.41 164(182) 2.89(2.55) 59.8 ~ - III-C 420 1.53 74(82) 2.91(2.57) 60.0 13.4(1 1.8) - III-Di 400 1.40 78(87) 2.98(2.63) 54.0 21.2(18.7) 13.3 III-D 2 400 1.50 73(82) 3.21(2.83) 42.5 23.4(20.7) 13.9 III-D3 400 1.52 73(81) 3.21(2.83) 39.0 23(20.3) 14.0 III-E 400 1.54 71(79) 3.13(2.76) 63.0 1 1.4(10.1) 5.4 Example IV - Draw-Texturing 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) yam using a false-twist texturing process. Using an apparatus as illustrated in Figure 5, the partially oriented yams prepared in Examples II-A to II-E were friction false- twist textured in accordance with the present invention. The yams were heated to a temperature of about 180°C as they passed through the heater and cooled to a temperature below the glass transition temperature of poly(trimethylene terephthalate) as they passed over the cooling plate. The remaining draw-texturing process conditions and the properties of the resulting draw-textured poly(trimethylene terephthalate) yams 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, S 2 /S 1 . The tension reported in Table V is as measured at tension monitoring device 63, shown in Figure 5. The ratio of disc speed to yarn speed reported in Table IV is determined by dividing the surface speed of the friction discs, S 4 , by the speed, Y s , of the yam as it passes through the twist insertion device. The processing conditions and properties for commercially available polyethylene terephthalate textured yams are provided for comparison. Table V Draw-Texturing Conditions and Textured Yarn Properties Example Draw Heater Temp, Take-up Disc Disc to Tension 5 , g/d Final Denier Final Tenacity, g/d Final Leesona Id. Ratio" °C Speed 2 (M/1M) Config 3 Yarn (dN/tex) (dtex) (dN/tex) E B , % Shrinkage Ratio 4 1V-Λ 1 509 180 500 1/3/1 1 95 35(31 ) 162( 180) 2 88(2 54) 43 8 47 7 cotnp A 1 710 225 500 1/5/1 1 95 65(57) 163( 181 ) 4 46(3 94) 20 2 42 04 IV-B 1 539 180 450 1/3/1 1 95 32(28) 159( 177) 2 50(2 21 ) 37 1 31 6 comp B 1 647 220 600 1/5/1 1 95 34(30) 156( 173) 4 06(3 58) 23 8 33 8 IV-C 1 539 180 500 1/3/1 1 95 27(24) 72(80) 2 90(2 56) 46 2 48 9 comp C 1 710 210 600 1/5/1 1 95 20(18) 73(81 ) 4 81(4 25) 23 2 50 5 IV-D 1 464 180 400 1/4/1 1 95 27(24) 72(80) 2 86(2 52) 46 2 16 05 comp D 1 560 200 500 1/7/1 1 95 20(18) 74(82) 4 39(3 87) 39 3 13 35 IV-E 1 495 180 400 1/4/1 2 1 33(29) 151( 168) 2 80(2 47) 39 0 10 25 comp E 1 590 200 500 1 /7/1 2 1 20(18) 160( 178) 3 80(3 35) 43 7 9 30 IV-F 1 470 180 400 1/4/1 1 95 28(25) 78(87) 3 15(2 78) 34 9 30 6 - S 2 /S|, 2 - S 3 3 - Entry guide discs/Working discs/Exit guide discs, 4 - S 4 Y s , 5 - Measured at tension monitor 63

Claims: WHAT WE CLAIM IS: 1. A partially oriented yarn made from a 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 yam has an elongation to break of at least 110%. 2. A process for spinning a partially oriented yam, 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. 3. The process of claim 2, wherein the spinning speed is between 1650 mpm and 2300 mpm. 4. A process for continuous draw-texturing a partially oriented feed yam made from a polymer substantially comprising poly(trimethylene terephthalate), comprising the steps of: (a) feeding a partially oriented feed yam through a heater, wherein the heater is set to a temperature between about 160°C and 200°C; (b) feeding the heated yarn to a twist insertion device, whereby the yam is twisted such that in a region between the twist insertion device and up to and including the heater, the yarn has a twist angle of about 46 degrees to about 52 degrees; and (c) winding the yam on a winder. 5. A draw textured yarn made by continuous draw-texturing a partially oriented yam with the following steps: (a) feeding the partially oriented yam of claim 1 through a heater, wherein the heater is set to a temperature between about 160°C and 200°C; (b) feeding the yam to a twist insertion device, whereby the yam is twisted such that in a region between the twist insertion device and up to and including the heater, the yam has a twist angle of about 46 degrees to about 52 degrees; and (c) winding the yam on a winder. 6. The process or yam of claims 4 or 5, wherein the twist insertion device is a friction spindle (such as disc type). 7. The process or yarn of claim 6, wherein the friction spindle comprises at least one entry guide disc, three to five working discs, and one exit guide disc. 8. The process or yam of claim 6 or 7, wherein the friction spindle comprises working discs spaced apart by about 0.75 to 1.0 mm. 9. The process or yam of claims 4 or 5, wherein the twist insertion device is a cross belt. 10. The process or yam of any of claim 4-9, further comprising the step of, prior to step (a), passing the yam through a twist isolation device. 11. The process or yam of claim of any of claims 4-10, wherein the polymer has an intrinsic viscosity of at least 0.70 dl/g and the partially oriented yam has an elongation to break of at least 110%. 12. The yam or process of any of the preceding claims, wherein the elongation to break is at least 120%. 13. The yarn or process of claim 11, wherein the elongation to break is at least 130%. 14. The yam or process of any of the preceding claims, wherein the elongation to break is up to 180%. 15. The yam or process of claim 14, wherein the elongation to break is up to 145%. 16. The yam or process of any of the preceding claims, wherein the intrinsic viscosity is at least 0.90 dl/g.

Inventors: HOWELL JAMES M, LONDON JOE FORREST JR, WATKINS MICHELLE H, HOWELL, JAMES, M., LONDON, JOE, FORREST, JR., WATKINS, MICHELLE, H.
Applicants: DU PONT, E.I. DU PONT DE NEMOURS AND COMPANY
Application year: 2001
Main classification: D01F6
IPC codes: D01F6, D02G1