Method for manufacturing polyethylene yarn having reduced surface roughness

Abstract

The present invention discloses: a method for manufacturing a polyethylene yarn having reduced surface roughness and reduced yarn breakage and fuzz formation by adjusting the contact time between a godet roller and a fiber during a stretching process; and a polyethylene cooling fabric obtained by weaving or knitting the yarn manufactured by the manufacturing method.

Description

Method for manufacturing polyethylene yarn with reduced surface roughness

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0115891, filed August 28, 2024, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a method for producing polyethylene yarn with reduced surface roughness.

[0004] As the climate crisis continues to cause heat waves, heavy rains, and droughts around the world, various technologies related to cooling fabrics are gaining attention as a response to climate change.

[0005] Cooling fabrics are manufactured by adding thermally conductive materials to synthetic fibers. They have the functionality of regulating body temperature and providing a cooling effect to the wearer. These cooling fabrics play a crucial role in promoting energy conservation and eco-friendly lifestyles. Given the climate crisis, demand for these high-value-added products is expected to continue to grow.

[0006] Coolness is divided into contact cooling and functional cooling. Contact cooling refers to a fabric's inherently low temperature, while functional cooling refers to fabrics with superior moisture absorption, quick-drying, and ventilation capabilities, resulting in a cooling sensation. Cooling fabrics, particularly contact cooling fabrics, offer the advantage of an immediate cooling effect, providing a cooling sensation immediately upon contact with the skin.

[0007] Contact cooling fabrics can be manufactured from various materials, and among them, the development of contact cooling fabrics using polyethylene fibers, such as those described in Patent Documents 1 and 2, is rapidly growing.

[0008] Polyethylene contact cooling fabrics are manufactured through melt spinning, drawing, and winding processes. This drawing process enhances the crystal orientation of the polyethylene, increasing strength and reducing surface roughness. However, if the thermal contact time between the godet roller and the fiber during the drawing process is prolonged, the fiber may break or fuzz. Lowering the godet roller temperature during the process can lead to defects such as increased fiber strength variation and surface roughness.

[0009] Therefore, in order to produce high-quality polyethylene fibers, a manufacturing method is needed that reduces the contact time while maintaining the temperature at which the heat exchanger is in contact with the heat exchanger during the drawing process.

[0010] [Prior Art Literature]

[0011] (Patent Document 1) KR Registered Patent No. 10-2137243 (Announced on July 23, 2020)

[0012] (Patent Document 2) KR Registered Patent No. 10-2183247 (Announced on November 26, 2020)

[0013] The present applicant has found that by controlling the contact time between the fiber and the godet roller among various parameters involved in the drawing process to produce high-quality polyethylene fiber, it is possible to minimize fiber breakage and pilling, thereby increasing the strength of the fiber and reducing the surface roughness, and thereby providing a technology that can obtain the effects of improved cooling function, a smooth surface, and excellent wear resistance in the fabric produced.

[0014] The present invention provides a method for producing polyethylene yarn, comprising the steps of melt-spinning a polyethylene polymer; drawing the produced undrawn yarn; and taking up the step, wherein the drawing is performed by multi-stage drawing using a plurality of godet rollers, and during the multi-stage drawing, the first godet roller is performed at a speed of 250 to 650 m / min, and the contact time between the first godet roller and the undrawn yarn is performed at 33% to 45% of the total contact time between the godet rollers and the fiber.

[0015] The polyethylene yarn of the present invention does not cause pilling and has low surface roughness, enabling the production of a fabric with a very smooth surface and excellent wear resistance.

[0016] The fabric manufactured from the polyethylene yarn of the present invention is a contact-cooling fabric that has an immediate cooling effect upon contact.

[0017] The method for manufacturing polyethylene yarn of the present invention has almost no yarn breakage during the drawing process, and by using this, the spinning processability is improved when manufacturing multifilament yarn, and the weaving or knitting efficiency is increased during the weaving or knitting process.

[0018] The polyethylene cooling fabric of the present invention can be applied to various fields, including cooling materials for clothing, and can play a leading role as a high value-added industry in light of the climate crisis.

[0019] Figure 1 is an SEM image of the yarn of Example 2.

[0020] Figure 2 is an SEM image of the yarn of Comparative Example 3.

[0021] In this specification, 'yarn' means yarn produced in a spinning process that has not been refined, bleached, dyed, or otherwise processed, and means yarn that has been melt-spun, cooled, and drawn.

[0022] The term 'fiber' as used herein means yarn unless otherwise specified.

[0023] In this specification, 'radiant yarn' means yarn radiated through a radiant chamber, also called radiant yarn, and means yarn before cooling treatment.

[0024] In this specification, 'unstretched yarn' means yarn that has been cooled and drawn before being subjected to stretching.

[0025] In this specification, 'drawn yarn' means a yarn that has been drawn.

[0026] In this specification, 'multifilament yarn' means yarn that has undergone a spinning process.

[0027] In this specification, 'pilling' includes fins, loops, and miscellaneous threads that occur on the exterior of the yarn. The fins (pilling) refer to a state in which several monofilaments are cut or cut monofilaments are pushed back and forth and bunched up, a loop refers to a state in which several monofilaments are protruding outward without being broken, and miscellaneous threads refer to a state in which external yarns are mixed in and bunched up.

[0028] In this specification, 'surface roughness' refers to the degree of unevenness of the surface in terms of how much of a flat surface is formed in the longitudinal direction of the yarn, and the lower the occurrence of hair, the lower the surface roughness.

[0029] The present invention provides a yarn with a reduced rate of yarn breakage and fuzzing, a reduced surface roughness, and a fabric produced thereby that has a cooling effect, a soft feel, and improved wear resistance. This is achieved through control of the drawing process.

[0030] Polyethylene yarn is manufactured by including a step of melt spinning a polyethylene polymer; a step of drawing the manufactured undrawn yarn; and a winding step.

[0031] The present invention is described in detail in each step below.

[0032] First, polyethylene resin is melted as a raw material for manufacturing polyethylene yarn.

[0033] Polyethylene resin has a weight average molecular weight (MW) of 50,000 to 99,000 g / mol and 0.941 to 0.965 g / cm 3 The polyethylene of the present invention used as a raw material has a density of 2 to 20 g / 10 min and a melt index (MI) (at 190°C) of 2 to 20 g / 10 min. Considering that the polydispersity index may decrease during the spinning process, the polyethylene used as a raw material has a polydispersity index (PDI) of 5.5 to 9, which is slightly higher than the target polydispersity index (i.e., the polydispersity index of the yarn).

[0034] If the weight average molecular weight (Mw) of the polyethylene resin is below the above range, it becomes difficult for the final polyethylene yarn to exhibit a strength exceeding 4 g / d, which may cause the fabric to fluff. Conversely, if it exceeds the above range, the polyethylene yarn has poor weaving properties due to excessively high strength and tensile modulus, and its stiffness is excessively high, making it unsuitable for use in the production of cool fabrics that are intended for contact with the user's skin.

[0035] If the polydispersity index of the polyethylene resin is below the above range, the relatively narrow molecular weight distribution results in poor flowability and poor processability during melt extrusion, resulting in uneven yarn thickness or breakage during the spinning process. Conversely, if the polydispersity index exceeds the above range, melt flowability and processability during melt extrusion improve; however, because an excessive amount of low-molecular-weight polyethylene is included, the strength of the final polyethylene yarn is reduced, making it easy for the fabric to become fluffy.

[0036] If the melt index of the polyethylene resin falls below the above range, the high viscosity and low flowability of the molten polyethylene make it difficult to ensure smooth flow within the extruder, degrading the uniformity and processability of the extrudate and increasing the risk of yarn breakage during the spinning process. Conversely, if a polyethylene resin with an excessively high melt index is used, the flowability within the extruder will be relatively good, but the strength of the resulting polyethylene yarn will be reduced.

[0037] Next, the molten mixture is radiated through a spinneret and then cooled.

[0038] Specifically, the molten mixture is conveyed through a spinneret by a screw and extruded through a plurality of holes formed in the spinneret.

[0039] The number of holes in the spinneret can be determined according to the DPF (Denier Per Filament) and fineness of the yarn to be manufactured. For example, when manufacturing a yarn with a total fineness of 75 denier, the spinneret can have 20 to 75 holes, and when manufacturing a yarn with a total fineness of 450 denier, the spinneret can have 90 to 450 holes, preferably 100 to 400 holes.

[0040] The melting process within the extruder and the extrusion process through the spinneret can be varied and applied depending on the melting index of the polyethylene chips, but specifically, it is preferable to perform the process at, for example, 150°C to 315°C, preferably 250°C to 315°C, and more preferably 265°C to 310°C. That is, it is preferable that the extruder and the spinneret are maintained at 150°C to 315°C, preferably 250°C to 315°C, and more preferably 265°C to 310°C.

[0041] It is recommended to use a 100-500 mesh filament filter (a mesh filter made of metal wire) during spinning. This is to remove foreign substances and impurities remaining in the polyethylene chips and to ensure uniform fineness between yarns by forming a uniform pressure on the chips remaining within the pack.

[0042] The emitter passes through a cooling zone to obtain cooled emitter, i.e., unstretched emitter.

[0043] Cooling may be performed using, but is not limited to, open quenching, circular closed quenching, radial outflow quenching, and radial inflow quenching methods, depending on the method of blowing cooling air. Preferably, the cooling is performed at 15°C to 40°C using cooling air at a wind speed of 0.2 to 1 m / sec. If the cooling temperature is less than 15°C, the elongation may be insufficient due to supercooling, which may cause yarn breakage during the drawing process. On the other hand, if the cooling temperature exceeds 40°C, solidification may proceed unevenly, increasing the fineness difference between undrawn yarns, which may cause yarn breakage during the drawing process of undrawn yarns or drawn yarns.

[0044] If necessary, an additional step of applying an oil to the unstretched yarn obtained after cooling using an oil roller or an oil jet may be included. The oil application step may be performed using the MO (metered oiling) method, and an oil that reduces the friction coefficient in a short period of time while simultaneously exhibiting excellent stretchability and thermal efficiency may be applied.

[0045] Next, the unstretched yarn is subjected to multi-stage stretching using equipment equipped with multi-stage stretching godet rollers.

[0046] Multi-stage stretching is performed by multi-stage stretching including multiple godet rollers (GR1...GRn) and is performed by controlling the total stretching ratio.

[0047] The total draw ratio applied during the drawing process should be adjusted to 2.5–7.5, preferably 3.5–7.5. Low draw ratios reduce the crystallinity of the polyethylene yarn, resulting in a lower Qmax value. Conversely, excessively high draw ratios lower physical properties such as strength, tensile modulus, and elongation, resulting in poor weaving properties and a stiff feel.

[0048] Multiple elongation godet rollers can be used for multi-stage elongation, preferably three or more, more preferably five-stage elongation godet rollers (GR1, GR2, GR3, GR4, GR5).

[0049] If the contact time between the godet roller and the fiber during the drawing process is prolonged, the fiber may break or fuzz may occur. Therefore, if the temperature of the godet roller is lowered to proceed with the drawing process, the yarn strength deviation and surface roughness increase. The fiber includes undrawn yarn that comes into contact with the first godet roller (GR1), drawn yarn that passes through it, and drawn yarn that passes through the first godet roller (GR1) and is drawn to the take-up roll.

[0050] In the present invention, the contact time with the godet rollers is controlled during the multi-stage stretching process. For example, the contact time with the first godet roller (GR1) is the longest, and the contact time decreases as it progresses to the second and nth godet rollers. When five godet rollers, GR1, GR2, GR3, GR4, and GR5, are used, the contact time with the first godet roller (GR1) is the longest, and the contact time decreases in the order of the second godet roller (GR2), the third godet roller (GR3), and the fourth godet roller (GR4), and the fourth and fifth godet rollers (GR4, GR5) proceed with the same contact time.

[0051] The contact time (Tn) of the godet roller (GRn) is calculated using the following equation 1.

[0052] [Formula 1]

[0053] Tn(millisecond, ms) = (Ln / Vn) × 60 × 1000

[0054] (In the above formula, Ln is the contact length of the godet roller, which is calculated by multiplying the diameter of each godet roller x the number of yarn turns x the circumference of the godet roller, and Vn is the speed of the godet roller.)

[0055] Compared to the total contact time for all the godet rollers, the first godet roller (GR1) makes contact for 33% to 45% of the time, the second godet roller (GR2) makes contact for 25% to 33% of the time, the third godet roller (GR3) makes contact for 9% to 15% of the time, the fourth godet roller (GR4) makes contact for 8% to 10% of the time, and the fifth godet roller (GR5) makes contact for 8% to 10% of the time.

[0056] The total contact time for all the godet rollers (GR1 to GRn) is 509 ms to 1250 ms and 535 ms to 1170 ms, wherein the first godet roller (GR1) is performed at 210 ms to 500 ms and 220 ms to 480 ms, the second godet roller (GR2) at 165 ms to 380 ms and 170 ms to 370 ms, the third godet roller (GR3) at 50 ms to 130 ms and 55 ms to 120 ms, the fourth godet roller (GR4) at 42 ms to 120 ms and 45 ms to 100 ms, and the fifth godet roller (GR5) at 42 ms to 120 ms and 45 ms to 100 ms.

[0057] If the total contact time of all the godet rollers (GR1 to GRn) is less than the above range, a sufficient draw ratio cannot be secured, and if it exceeds the above range, the long contact time causes fiber breakage or fiber fuzziness. In particular, the contact time of the first godet roller (GR1) is directly related to the fiber breakage and fuzziness, and if the contact time of the first godet roller (GR1) is performed within the above range, the fiber breakage of the undrawn yarn is reduced and fuzziness is not generated, enabling the production of a yarn with a smooth surface.

[0058] The temperature of the godet roller along with the contact time is related to the strength and surface roughness of the yarn.

[0059] In the multi-stage stretching process of the present invention, the temperature of the godet rollers is also controlled. For example, the temperature of the first godet roller (GR1) is the lowest, and the temperature increases as it progresses to the second and nth godet rollers (GR2 to GRn). When five godet rollers, GR1, GR2, GR3, GR4, and GR5, are used, the temperature of the first godet roller (GR1) is the lowest, and the temperature increases in the order of the second godet roller (GR2) and the third godet roller (GR3), and the third to fifth godet rollers (GR3 to GR5) are performed at the same temperature.

[0060] Specifically, stretching is performed at 110°C to 140°C, the first godet roller (GR1) at 110°C to 125°C, the second godet roller (GR2) at 120°C to 130°C, the third godet roller (GR3) at 125°C to 140°C, the fourth godet roller (GR4) at 125°C to 140°C, and the fifth godet roller (GR5) at 125°C to 140°C.

[0061] The first godet roller (GR1) has a relatively long contact time compared to other godet rollers, but the drawing is carried out at a relatively low temperature. As the contact time decreases as you go to the second to fifth godet rollers (GR2 to GRn), the drawing is carried out at a relatively high temperature.

[0062] The multi-stage drawn yarn is wound on a winder by performing multi-stage drawing and heat setting simultaneously to produce the polyethylene yarn of the present invention.

[0063] In the present invention, the first godet roller (GR1) has a speed of 250 to 650 m / min and 300 to 600 m / min. The speed of the first godet roller (GR1) is to control the contact time of the undrawn yarn with the first godet roller (GR1). If the speed is too slow, the contact time increases, and if it is too fast, the contact time decreases.

[0064] During the drawing process, the non-uniformity of the undrawn or drawn yarn increases due to thermal or physical stress applied to the yarn, or the puckering that occurs during drawing, which causes yarn breakage in the undrawn or drawn yarn during the multi-stage drawing stage. At this time, the undrawn yarn is the fiber that comes into contact with the first godet roller (GR1), and the drawn yarn is the fiber that passes through the first godet roller (GR1) and reaches the take-up roll.

[0065] The number of yarn breaks is defined as the number of times the yarn is cut during its movement from the first godet roller (GR1) to the take-up roll, based on 24-hour operation. The number of yarn breaks for the drawn yarn according to the present invention is one or less, preferably zero. As yarn breaks increase, yarn quality deteriorates, ultimately leading to a significant drop in productivity.

[0066] The multi-stage stretched yarn through the above process is wound on a winder to produce the polyethylene yarn of the present invention.

[0067] Winding is performed at 1200 to 3300 m / min through a winding roll.

[0068] The polyethylene yarn of the present invention has a crystallinity of 60% to 85% and a density of 0.941 to 0.965 g / cm 3 It is a high-density polyethylene (HDPE) yarn with a density of .

[0069] The polyethylene yarn of the present invention has a strength of 4 g / d or more and in the range of 4 to 5.5 g / d, measured at a length of 250 mm, an ambient temperature of 20±2℃, and a relative humidity of 65±4% according to ASTM D2256.

[0070] The polyethylene yarn of the present invention has an elongation of 25% or less and 20 to 25%, measured at a length of 250 mm, an ambient temperature of 20±2℃, and a relative humidity of 65±4%, according to ASTM D2256.

[0071] The polyethylene yarn of the present invention may have a DPF (Denier Per Filament) of 1 to 5. That is, the polyethylene yarn may include a plurality of filaments each having a fineness of 1 to 5 denier. In addition, the polyethylene yarn of the present invention may have a total fineness of 75 to 450 denier. If the fineness of each filament in the polyethylene yarn having a predetermined total fineness exceeds 5 denier, the smoothness of the fabric manufactured from the polyethylene yarn will be insufficient and the contact area with the body will be reduced, so that it will not be able to provide sufficient cooling sensation to the user. In general, the DPF can be adjusted through the output amount and draw ratio of the spinneret.

[0072] The polyethylene yarn of the present invention may have a circular cross-section or a non-circular cross-section, but it is preferable to have a circular cross-section in that it can provide a uniform cooling sensation to the user.

[0073] The polyethylene yarn of the present invention does not cause pilling and has a very low surface roughness, enabling the production of a fabric with a very smooth surface and excellent wear resistance.

[0074] After winding 10,000 m of 400d (denier) yarn on a bobbin, the surface of the wound yarn is visually observed, and the average value obtained after a total of 10 measurements is calculated. As a result, the polyethylene yarn of the present invention has 1 or less, preferably 0, hairs measured by the above method.

[0075] Yarns with reduced surface roughness exhibit more even fiber properties and thickness, which reduces breakage of multifilament yarns during the spinning process and minimizes raw material loss, thereby improving spinning processability. Furthermore, yarns with reduced surface roughness yield multifilament yarns with greater strength and greater even thickness. Furthermore, they reduce friction during weaving or knitting, thereby increasing weaving or knitting efficiency. Consequently, fabrics woven or knitted from multifilament yarns with improved physical properties exhibit a smooth surface and a clearly defined texture, as well as increased gloss and wear resistance.

[0076] The polyethylene yarn of the present invention can be produced into a polyethylene fabric, preferably a polyethylene cooling fabric, by a known method.

[0077] The polyethylene yarn of the present invention is a yarn capable of weaving a cool-feeling fabric, and the cool-feeling fabric is a contact cool-feeling fabric.

[0078] The contact coolness of a contact cool fabric can be measured according to the JIS L 1927: 2020 method (Japanese Industrial Standards), and the maximum instantaneous heat absorption Qmax is measured after a heat plate with a temperature difference between the fabric and the surface of the fabric is brought into contact with it. In the present invention, the measuring equipment used was the Thermofeel PF-QMM-01 equipment, and the test conditions were 20±2℃, 65±4% relative humidity, and a heat plate (T-box) of 40±2℃ was brought into contact with the fabric of 20±2℃, and the test was repeated 5 times in total, and the average value was calculated. The Qmax value in the contact coolness test result was 0.15 W / cm 2 If this is above, it can be seen that there is a contact cooling effect, and the higher the number, the better the contact cooling function can be seen.

[0079] The polyethylene cool-touch fabric of the present invention exhibits superior physical properties and is woven or knitted with uniform yarns without causing yarn breakage during stretching, thereby improving wear resistance. Specifically, the fabric can be provided with a pilling resistance of grade 4 or higher, or better, grades 4 to 5, as measured under conditions of 14,400 rotations according to the pilling box method specified in KS K ISO 12945-1:2014.

[0080] The polyethylene cooling fabric of the present invention has a density of 70 to 1300 g / m 2 It can be a woven fabric or knitted fabric having a weight per unit area (i.e., an area density). If the area density of the fabric is below the above range, the fabric becomes insufficiently dense, resulting in many voids within the fabric, which reduce the coolness of the fabric. Conversely, if the area density of the fabric exceeds the above range, the fabric becomes very stiff due to the excessively dense fabric structure, causing problems in the tactile sensation felt by the user, and the high weight causes problems in use.

[0081] Made from the aforementioned polyethylene yarn, the polyethylene cool-touch fabric is comfortable and cool, as it doesn't feel sticky due to sweat or moisture. It also absorbs and dries quickly, effectively absorbing sweat and moisture. Furthermore, it doesn't cling to the body, maintaining a soft, fluffy feel. It also absorbs body heat, providing a cool and refreshing sensation to the touch.

[0082] The fabric made from the polyethylene yarn of the present invention can be applied to a variety of fields. For example, the cooling fabric can be used as a cooling material for various types of clothing, including sportswear, workwear, and innerwear, as well as bedding, medical underpads, stroller pads, and pet clothing and pads.

[0083] Hereinafter, an embodiment according to the present invention will be described.

[0084] [Measurement of physical properties]

[0085] - Strength and elongation: Measured according to ASTM D2256, measured at a sample length of 250 mm, an ambient temperature of 20℃, and a relative humidity of 65%. The stress at the breaking point of the curve was defined as strength (g / d), and the increased length was defined as elongation (%). Each value was defined as the average value of 10 measurements.

[0086] - Fineness: The fineness of the fineness was measured using a wrap reel device according to the KS K ISO 2060 standard, and the unit was defined as d (denier). A total of five measurements were taken, and the average value was calculated.

[0087] - Number of times the yarn is cut: The number of times the yarn is cut while moving from the first godet roller to the take-up roll is measured based on 24-hour operation.

[0088] - Appearance: This is defined as checking the yarn wound on the bobbin 10 times at 10,000m intervals and measuring the number of times the appearance is found.

[0089] - Surface roughness: The yarn surface was measured using a thermal type FE-SEM.

[0090] - Crystallinity: The crystallinity of polyethylene yarn was measured using an XRD device (X-ray Diffractometer) [Manufacturer: PANalytical, Model: EMPYREAN]. Specifically, polyethylene yarn was cut to prepare a sample with a length of 2.5 cm, and the sample was fixed to a sample holder, after which measurements were performed under the following conditions.

[0091] *Light source (X-ray source): Cu-Kα radiation

[0092] *Power: 45 KV x 25mA

[0093] *Mode: Continuous scan mode

[0094] *Scan angle range: 10~40°

[0095] *Scan speed: 0.1° / sec

[0096] - Qmax: Thermofeel PF-QMM-01 equipment was used according to JIS L 1927: 2020, and the average value was calculated after 5 measurements were made by contacting a 40±2℃ hot plate (T-box) to a 20±2℃ fabric at 20±2℃ and 65±4% RH.

[0097] - Abrasion Resistance: The fabric's pilling resistance was measured at 14,400 rotations using a Martindale tester, according to the pilling box method specified in KS K ISO 12945-1:2014. The pilling resistance grades are as follows. A higher grade indicates better abrasion resistance.

[0098] - Grade 1: Very severe peeling

[0099] - Grade 2: Severe peeling

[0100] - Grade 3: Moderate peeling

[0101] - Grade 4: Slight peeling

[0102] - Grade 5: No peeling at all

[0103] Test Example 1

[0104] [Yarn manufacturing]

[0105] Polyethylene resin (80,000 g / mol) pellets with the contents shown in Table 1 below were fed into an extruder, extruded through a spinneret at a spinning temperature of 260°C, and the produced spun yarn was moved to a cooling zone to cool. Next, the undrawn yarn was drawn five times to an overall draw ratio (DR) of 5.0 and wound to produce polyethylene yarn. The properties of the yarn were then measured and shown in the table below.

[0106] [Evaluation Results]

[0107] Classification Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 1st Godet Roller Speed ​​(m / min) 600 500 400 300 700 200 100 Contact Time (ms) 2 36 28 335 347 120 27 0 7 14 14 Temperature (℃) 120 120 120 120 120 120 120 2nd Godet Roller Contact Time (ms) 18 12 17 27 236 21 5 5 44 10 87 Temperature (℃) 125 125 125 125 125 125 125 3rd Godet Roller Contact Time (ms) 57688511349170340 Temperature (℃) 1301301301301301301304th Godet Roller Contact Time (ms) 4757719440142283 Temperature (℃) 1301301301301301301301305th Godet Roller Contact Time (ms) 4757719440142283 Temperature (℃) 130130130130130130130130130 Total Godet roller total contact time (ms) 568682852113448617053407 Winding speed (m / min) 300025002000150035001000500 Physical properties Denier 411.0412.1411.6411.2411.2411.6411.9 Strength (g / d) 5.45.15.04.84.04.74.5 Elongation (%) 22242525212625 Crystallinity (%) 76.575.976.277.479.472.169.5 Number of times of elongation (times) 0000457 Appearance (hair, number) 00007912

[0108] As shown in the table above, the yarns of Examples 1 to 4, in which the speed, contact time, and temperature of the first godet roller were controlled, had excellent strength and elongation. In addition, no breakage occurred during the drawing process, and no fluff was observed in the appearance. In Comparative Example 1, the yarn was manufactured through a short contact time between the first to fifth godet rollers and the undrawn and drawn yarns due to the fast speed of the first godet roller. As a result, the strength of the yarn was greatly reduced, yarn breakage occurred during the drawing process, and many fluffs were also observed.

[0109] The yarn of Comparative Example 2 was manufactured by lengthening the contact time of the undrawn yarn and drawn yarn with the godet roller, and the strength of the yarn was slightly increased compared to the yarn of Comparative Example 1, but yarn breakage occurred during the drawing process and many hairs were also observed.

[0110] The yarn of Comparative Example 3 was manufactured by greatly reducing the speed of the godet roller and making the contact time between the undrawn yarn and the drawn yarn very long. Compared to the yarn of Comparative Example 2, the strength was reduced, yarn breakage occurred during the drawing process, and many hairs were also observed.

[0111] Therefore, it can be seen that controlling the speed, contact time and temperature of the first godet roller in the yarn drawing process can improve the properties of the yarn and prevent yarn breakage and pilling.

[0112] Fig. 1 is an SEM (Scanning Electron Microscope) image of the yarn of Example 2, showing that the surface was very smooth. In comparison, Fig. 2 is an SEM (Scanning Electron Microscope) image of the yarn of Comparative Example 3, showing that the surface was rough and had fur.

[0113] Test Example 2

[0114] [Fabric Manufacturing]

[0115] The manufactured yarn is woven to a cotton density of 500 g / m 2 A cooling fabric was manufactured. The physical properties of the manufactured cooling fabric were measured and shown in the table below.

[0116] [Evaluation Results]

[0117] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Qmax(W / cm 2 )0.3020.3140.3020.3050.2940.2750.265Wear resistance (grade)5554-5433

[0118] As shown in the table above, the cool fabrics manufactured with the yarns of Examples 1 to 4 have a thermal conductivity of 0.3 W / cm 2The fabrics exhibited excellent wear resistance with a Qmax value above and little or no pilling. In comparison, the cool fabrics manufactured from the yarns of Comparative Examples 1 to 3 showed a decrease in wear resistance along with a decrease in Qmax value.

Claims

1. A method for manufacturing polyethylene yarn, comprising the steps of melt spinning a polyethylene polymer; drawing the manufactured undrawn yarn; and winding; The above stretching is performed by multi-stage stretching including a plurality of godet rollers, A method for manufacturing polyethylene yarn, wherein the first godet roller is operated at a speed of 250 to 650 m / min during the above multi-stage stretching, and the contact time between the first godet roller and the undrawn yarn is 33% to 45% of the total contact time between the godet roller and the fiber.

2. In paragraph 1, The total contact time of the fibers for the entire above-mentioned rollers is 509 ms to 1250 ms, A method for manufacturing polyethylene yarn, wherein the contact time between the first godet roller and the unstretched yarn is 210 ms to 500 ms.

3. In paragraph 1, A method for manufacturing polyethylene yarn, wherein the temperature of the first godet roller is 110°C to 125°C.

4. In paragraph 1, A method for manufacturing polyethylene yarn, wherein the above multi-stage stretching is performed using five godet rollers.

5. In paragraph 1, A method for manufacturing polyethylene yarn, wherein the above stretching is performed at a total stretching ratio of 2.5 to 7.

5.

6. In paragraph 1, A method for manufacturing polyethylene yarn, wherein the above winding is performed at a speed of 1200 to 3300 m / min.

7. In paragraph 1, A method for manufacturing polyethylene yarn, wherein the polyethylene yarn has a strength of 4 g / d or more as measured at a length of 250 mm, an ambient temperature of 20±2℃, and a relative humidity of 65±4% according to ASTM D2256.

8. In paragraph 1, A method for manufacturing polyethylene yarn, wherein the above polyethylene yarn has an elongation of 25% or less as measured at a length of 250 mm, an ambient temperature of 20±2℃, and a relative humidity of 65±4% according to ASTM D2256.

9. In paragraph 1, A method for manufacturing polyethylene yarn, wherein the polyethylene yarn has a total fineness of 75 to 450 denier and includes a plurality of filaments each having a fineness of 1 to 5 denier.

10. In paragraph 1, A method for manufacturing polyethylene yarn, wherein the polyethylene yarn has a crystallinity of 60% to 85%.

11. In paragraph 1, A method for manufacturing polyethylene yarn, wherein the polyethylene has a weight average molecular weight (MW) of 50,000 to 99,000 g / mol.

12. In paragraph 1, A method for manufacturing polyethylene yarn, wherein the number of hairs found is 0 after checking the above polyethylene yarn 10 times at intervals of 10,000 m of yarn wound on a bobbin.

13. Polyethylene cooling fabric manufactured from the polyethylene yarn of paragraph 1.

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