Polyethylene fibers have improved post-processing capabilities, and fabrics containing these fibers exist.

Abstract

The invention proposes a polyethylene fiber capable of improved post-processing, and more specifically, the invention proposes a polyethylene fiber that maintains good mechanical properties even under harsh environments such as high temperatures, making it capable of improved post-processing such as dyeing or coating.

Description

Polyethylene yarn with improved post-processing properties and fabric containing the same

[0001] The present invention relates to a polyethylene yarn with improved post-processing properties and a fabric comprising the same.

[0002] Polyethylene resin is increasingly used in engineering plastics, film fibers, and nonwovens due to its low price, chemical resistance, and excellent processability. In the textile industry, it is manufactured into monofilaments and multifilaments, expanding its applications to include clothing and industrial applications. In particular, interest in high-performance polyethylene fibers, which require high strength and modulus, is growing in line with recent textile trends.

[0003] In U.S. Patent No. 4,228,118, a polyethylene resin having a number average molecular weight of 20,000 or more and a weight average molecular weight of 125,000 or less was used, and a spinning temperature of 220 to 335°C was used, and the minimum spinning speed was 30 m / min. Then, the spinning speed was drawn 20 times or more to produce a fiber having a density of 10 to 20 g / d. However, this method has limitations in the production volume due to the low spinning speed depending on the nozzle hole number and spin draw method for commercial production of polyethylene fibers, and it is difficult to produce polyethylene fibers with excellent uniformity and spinning workability when producing tens to hundreds of multifilaments.

[0004] Polyethylene fibers typically have unique properties, such as high strength, lightweight, and chemical resistance, making them suitable for a wide range of applications, including safety products, leisure goods, and daily necessities. However, compared to polyethylene terephthalate fibers or polyamide fibers, which have relatively high melting points, polyethylene fibers have a low melting point, which makes their properties susceptible to deterioration at high temperatures. This limits the possible post-processing conditions. To address these issues, there is an urgent need to manufacture polyethylene yarns that maintain their mechanical properties even after high-temperature post-processing.

[0005] The purpose of the present invention is to provide a polyethylene yarn with improved post-processing properties by maintaining mechanical properties even in a high-temperature environment.

[0006] In addition, it provides a fabric with excellent mechanical properties, including polyethylene yarn with improved post-processing properties.

[0007] The polyethylene yarn according to the present invention has a melt index (MI) of 0.3 to 3 g / 10 min as measured according to ASTM D1238, a ratio (B / A) of strength (B) measured after heat treatment at 120°C for 30 minutes to strength (A) measured at room temperature according to ASTM D885 of 85% or more, and a ratio (C / A) of strength (C) measured after heat treatment at 50°C for 30 minutes to strength (A) measured at room temperature of 90% or more.

[0008] In a polyethylene yarn according to one embodiment of the present invention, the polyethylene yarn may have a crystallinity of 60 to 85%.

[0009] In a polyethylene yarn according to one embodiment of the present invention, the polyethylene yarn may have a crystal size of 200 Å or more in a direction parallel to the fiber axis (002 plane) and a crystal size of 110 Å or more in a direction perpendicular to the fiber axis (110 plane), as measured by an X-ray diffraction pattern using CuKα rays.

[0010] In a polyethylene yarn according to one embodiment of the present invention, the polyethylene yarn may have a melting temperature of 130 to 140°C.

[0011] In a polyethylene yarn according to one embodiment of the present invention, the polyethylene yarn has a density of 0.93 to 0.97 g / cm 3 It could be.

[0012] In a polyethylene yarn according to one embodiment of the present invention, the dry heat shrinkage rate of the polyethylene yarn is 2.5% or more.

[0013] In one embodiment of the polyethylene yarn of the present invention, the polyethylene yarn may have a strength of 1 to 20 g / d as measured according to ASTM D2256.

[0014] In one embodiment of the polyethylene yarn of the present invention, the polyethylene yarn may have a breaking elongation of 20% or less as measured according to ASTM D2256.

[0015] The fabric according to the present invention comprises the polyethylene yarn described above.

[0016] In a fabric according to one embodiment of the present invention, the abrasion resistance (cycles) of the fabric may be 500 or more.

[0017] The polyethylene yarn according to the present invention can maintain a certain level of strength or higher in a high-temperature environment and thus have excellent post-processing properties.

[0018] In addition, the fabric according to the present invention can maintain the excellent mechanical properties unique to polyethylene by including polyethylene yarn with excellent post-processing properties, and can be applied to various fields such as safety products, leisure products, daily necessities, or cooling materials.

[0019] Figure 1 is a schematic diagram for measuring the strength of polyethylene yarn according to one embodiment of the present invention.

[0020] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings attached to the present invention. In describing the present invention, specific descriptions of related known functions or configurations are omitted to avoid obscuring the gist of the present invention.

[0021] The following specific examples or embodiments are only a reference for explaining the present invention in detail, and the present invention is not limited thereto and may be implemented in various forms.

[0022] Unless otherwise defined herein, all technical and scientific terms have the meaning commonly understood by those of ordinary skill in the art to which this invention pertains. The terminology used in the description of the present invention is solely for the purpose of describing specific embodiments and is not intended to limit the present invention.

[0023] Additionally, the singular forms used in the specification may be intended to include the plural forms as well, unless the context specifically indicates otherwise.

[0024] Additionally, when a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0025] Units used below without special mention are based on weight, and for example, units of % or ratio mean weight% or weight ratio.

[0026] The inventors of the present invention noted that polyethylene yarn possesses unique properties such as high strength, lightweight, and chemical resistance, as well as excellent cooling properties due to its high crystallinity. However, its low melting point makes it vulnerable to high temperatures, making post-processing extremely difficult. Accordingly, they intensified their research and discovered that polyethylene yarn, when it satisfies specific melt index and strength requirements, maintains high crystallinity and mechanical properties even after post-processing, thereby completing the present invention.

[0027] In this specification, polyethylene yarn refers to monofilaments and multifilaments manufactured from polyethylene chips as raw material through processes such as spinning and drawing. For example, polyethylene yarn may comprise 40 to 500 filaments, each having a fineness of 1 to 3 denier, and may have a total fineness of 100 to 1,000 denier.

[0028] The polyethylene yarn according to the present invention is characterized in that it has a melt index (MI, @190℃) of 0.3 to 3 g / 10 min measured at 190℃, 2.16 kg according to ASTM D1238, a ratio (B / A) of strength (B) measured after heat treatment at 120℃ for 30 minutes to strength (A) measured at room temperature according to ASTM D885 is 85% or more, and a ratio (C / A) of strength (C) measured after heat treatment at 50℃ for 30 minutes to strength (A) measured at room temperature is 90% or more.

[0029] Specifically, the ratio (B / A) of the strength (B) measured after heat treatment at 120°C for 30 minutes to the strength (A) measured at room temperature may be 87% or more, and advantageously 90% or more. In addition, the ratio (C / A) of the strength (C) measured after heat treatment at 50°C for 30 minutes to the strength (A) measured at room temperature may be 92% or more, and advantageously 95% or more.

[0030] Additionally, the melting index (MI) may advantageously be 0.4 to 3 g / mol, more advantageously 0.7 to 3 g / mol.

[0031] Polyethylene yarns that satisfy such high strength and melting index have the advantage of being advantageous for post-processing such as weaving and twisting, as their properties hardly deteriorate even when exposed to high temperatures for long periods of time.

[0032] In addition, the polyethylene yarn may have a polydispersity index (PDI) of 1 to 20, specifically 3 to 15, and more specifically 5 to 10, and at this time, the weight average molecular weight (Mw) may be 600,000 g / mol or less, specifically 80,000 to 500,000 g / mol, and more specifically 200,000 to 400,000 g / mol. The polyethylene yarn having the polydispersity index and weight average molecular weight in the above range has good melt flowability during melt extrusion of the yarn, prevents thermal decomposition, and does not cause yarn breakage during stretching, thereby ensuring fairness, thereby manufacturing a yarn with uniform physical properties, and providing a yarn with excellent durability. At this time, the number average molecular weight is not limited as long as it can satisfy the above-described PDI value for the above-described weight average molecular weight.

[0033] In addition, the polyethylene yarn may have a crystallinity of 60 to 90%, more preferably 60 to 85%, and even more preferably 65 to 85%, but is not limited thereto. The crystallinity of the polyethylene yarn can be derived through crystallization analysis using an X-ray diffractometer. In a range where the crystallinity satisfies the above range, heat can be rapidly diffused and dissipated through lattice vibrations called 'phonons' in the direction of molecular chains connected through covalent bonds of polyethylene, thereby achieving excellent thermal conductivity.

[0034] In addition, the polyethylene yarn may satisfy a crystal size of 200Å or more in a direction parallel to the fiber axis (002 plane) and 110Å or more in a direction perpendicular to the fiber axis (110 plane), as measured by an X-ray diffraction pattern using CuKα rays. Specifically, the crystal size in the direction parallel to the fiber axis may be 210Å to 360Å, and more specifically, 220Å to 350Å. In addition, the crystal size in the direction perpendicular to the fiber axis may be 120Å to 190Å, and advantageously 130Å to 180Å, but is not limited thereto. However, within the above range, the polyethylene yarn may exhibit high strength and low shrinkage characteristics, and may not only satisfy excellent heat resistance but also improve heat absorption, thereby improving coolness.

[0035] Additionally, polyethylene yarn can have a melting temperature of 130 to 140°C. Specifically, it can be 138 to 140°C, but is not limited thereto. However, yarns that satisfy the above melting temperature can maintain mechanical properties even at relatively high temperatures.

[0036] In addition, the polyethylene yarn has a density of 0.93 to 0.97 g / cm 3 , specifically, 0.941 to 0.965 g / cm 3 Polyethylene yarn satisfying the above density maintains its mechanical properties even when exposed to high temperatures for a long time, and its heat resistance increases, resulting in a lower shrinkage rate.

[0037] Specifically, the polyethylene yarn may have a dry heat shrinkage of 1.5 to 3.5%, specifically 2 to 3%, or 2.5 to 3%.

[0038] The polyethylene yarn may have a tenacity of 1 to 25 g / d, as measured according to ASTM D2256. Preferably, the tenacity is 1 to 20 g / d, and more preferably, 7 to 20 g / d. Polyethylene yarns satisfying the above tenacity have relatively high flexibility and excellent weaving properties, resulting in superior quality fabrics when subsequently woven or knitted into fabrics.

[0039]

[0040] Hereinafter, a method for manufacturing the polyethylene yarn of the present invention will be described in detail. The polyethylene yarn of the present invention is not limited to the manufacturing method as long as it satisfies the above-mentioned ranges of physical properties such as PDI, strength ratio, and intensity. The following describes one embodiment.

[0041] First, a step of melting polyethylene chips to obtain polyethylene melt;

[0042] A step of spraying the polyethylene melt through a nozzle having a plurality of nozzle holes;

[0043] A step of cooling and stretching and heat-setting a plurality of filaments formed when the polyethylene melt is discharged from the nozzle holes at a total stretching ratio of 5 to 20 times; and

[0044] It may include a step of winding the multifilament yarn that has been stretched and heat-set.

[0045] To explain each step in detail, first, polyethylene in the form of chips is fed into an extruder and melted to obtain a polyethylene melt.

[0046] The above polyethylene chips may have a polydispersity index (PDI) of greater than 5 and less than 9, preferably 5.5 to 8. In addition, it may have a melt index (MI) of 0.3 to 3 g / 10 min, preferably 0.4 to 3 g / mol, and more preferably 0.7 to 3 g / mol. In addition, it may have a weight average molecular weight (Mw) of 600,000 g / mol or less, more specifically 80,000 to 600,000 g / mol, preferably 100,000 to 500,000 g / mol, and more preferably 200,000 to 400,000 g / mol.

[0047] Molten polyethylene is conveyed through a die by a screw within the extruder and extruded through a plurality of holes formed in the die. The number of holes in the die 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 die can have 20 to 75 holes, and when manufacturing a yarn with a total fineness of 450 denier, the die can have 90 to 450 holes, preferably 100 to 400 holes.

[0048] The melting process within the extruder and the extrusion process through the die can be varied and applied depending on the melting index of the polyethylene chips, but specifically, for example, it can be performed at 150 to 315°C, preferably 220 to 300°C, and more preferably 250 to 290°C. That is, it is preferable that the extruder and the die are maintained at 150 to 315°C, preferably 220 to 300°C, and more preferably 250 to 290°C.

[0049] When the above-mentioned spinning temperature is less than 150℃, the low spinning temperature may cause the polyethylene to not melt uniformly, making spinning difficult, and excessive shear stress may be generated inside the nozzle, which may cause the melt fracture phenomenon to worsen. On the other hand, when the spinning temperature exceeds 315℃, the thermal decomposition of polyethylene may be accelerated, making it difficult to express the physical properties at the target level. The ratio of the hole length (L) to the hole diameter (D) of the spinneret, L / D, may be 3 to 40. When L / D is less than 3, the die swell phenomenon occurs during melt extrusion, and it becomes difficult to control the elastic behavior of the polyethylene, resulting in poor spinnability. When L / D exceeds 40, the necking phenomenon of the molten polyethylene passing through the spinneret may cause thread breakage and an uneven discharge phenomenon due to a pressure drop.

[0050] As molten polyethylene is discharged from the holes of the detention chamber, the difference between the radiation temperature and room temperature initiates solidification of the polyethylene, forming semi-solid filaments. In this specification, both semi-solid filaments and fully solidified filaments are collectively referred to as "filaments."

[0051] A plurality of the above filaments are completely solidified by cooling in a cooling section (or "quenching zone"). Cooling of the filaments can be performed by air cooling.

[0052] It is preferable that the cooling of the filaments in the cooling section be performed to a temperature of 15 to 40°C using cooling wind at a wind speed of 0.2 to 1 m / sec. If the cooling temperature is less than 15°C, the elongation is insufficient due to supercooling, which may cause breakage during the drawing process. If the cooling temperature exceeds 40°C, the fineness difference between the filaments increases due to uneven solidification, which may cause breakage during the drawing process.

[0053] Additionally, by performing multi-stage cooling in the cooling section, crystallization can be made more uniform.

[0054] More specifically, the cooling section may be divided into two or more sections. For example, if it is composed of three cooling sections, it is preferable that the temperature be designed to gradually decrease from the first cooling section to the third cooling section. Specifically, for example, the first cooling section may be set to 40 to 80°C, the second cooling section may be set to 30 to 50°C, and the third cooling section may be set to 15 to 30°C.

[0055] In addition, by setting the wind speed in the first cooling section to the highest, a fiber with a smoother surface can be manufactured. Specifically, the first cooling section may be configured to cool to 40 to 80°C using cooling wind at a wind speed of 0.8 to 1 m / sec, the second cooling section may be configured to cool to 30 to 50°C using cooling wind at a wind speed of 0.4 to 0.6 m / sec, and the third cooling section may be configured to cool to 15 to 30°C using cooling wind at a wind speed of 0.2 to 0.5 m / sec. By adjusting the conditions as described above, a yarn with a higher degree of crystallinity and a smoother surface can be manufactured.

[0056] Next, the cooled and fully solidified filaments are focused using a focusing device to form a multifilament.

[0057] The polyethylene yarn of the present invention can be manufactured through a direct spin drawing (DSD) process. That is, the multifilament is directly transferred to a multi-stage drawing unit including a plurality of godet roller sections, and is multi-stage drawn at a total draw ratio of 5 to 20 times, preferably 8 to 15 times, and then wound on a winder.

[0058] For example, the stretching step using the plurality of godet rollers is preferably performed as a multi-stage stretching of two or more stages. Preferably, the stretching step may be performed as a multi-stage stretching of two or more stages and 20 or fewer stages using the plurality of godet rollers. If the multi-stage stretching is less than two stages, rapid stretching may occur in each section of the godet rollers, which may increase the frequency of hair formation during filament yarn production and increase the initial modulus, which may make the fabric excessively stiff. In addition, if the multi-stage stretching is performed in 20 or more stages, friction between the filament yarn and the godet rollers may increase, which may cause filament damage and yarn breakage.

[0059] In addition, even if polyethylene chips having a polydispersity index (PDI) of 5 to 10 and a melt index (MI) of 0.3 to 3 g / 10 min at 190°C are used, if the draw ratio, draw temperature, and number of stages according to the method of the present invention are not satisfied, the intended properties cannot be satisfied. For example, during the draw, the maximum draw temperature may be 100 to 150°C, and if the draw temperature is less than 100°C, the amount of heat transferred to the yarn is not sufficient, so that the draw efficiency decreases and the draw yarn breakage occurs severely, and if it exceeds 150°C, the filaments may fuse, which may lower the yarn strength. The total draw ratio may be 5 to 20 times, and multi-stage draw of two or more stages may be performed. The above maximum drawing temperature means the highest temperature during the drawing section, and the above total drawing ratio means the final drawing ratio of the fiber after the last drawing compared to the fiber before drawing.

[0060] For example, the multi-stage stretching may be performed using a plurality of godet rollers in two or more stages, more specifically, four or more stages and twenty or less stages. The temperature of the first godet roller (GR1) among the plurality of godet rollers (GR1...GRn) may be 50 to 80° C., and the temperature of the last godet roller (GRn) may be 100 to 150° C. The temperature of each of the remaining godet rollers except for the first and last godet roller sections (GR1, GRn) may be set to be equal to or higher than the temperature of the godet roller immediately preceding it. The temperature of the last godet roller section (GRn) may be set to be equal to or higher than the temperature of the godet roller section immediately preceding it, but may also be set somewhat lower than that.

[0061] In addition, by providing 1 to 5% of shrinkage (relaxation) in the final stretching section during multi-stage stretching, a yarn with superior durability can be provided.

[0062] More specifically, for example, the multi-stage stretching may be composed of a total of four godet roller sections, and the first godet roller section may be set to stretch 2 to 4 times at 50 to 80°C, the second godet roller section may be set to stretch 3 to 10 times at 70 to 100°C, the third godet roller section may be set to stretch 1.1 to 3 times at 80 to 110°C, and the fourth godet roller section may be set to contract and stretch (relax) 1 to 5% at 100 to 150°C. Each of the first to fourth godet roller sections may be composed of multiple godet rollers. Specifically, for example, it may be composed of two or more godet rollers, and more specifically, two to ten godet rollers.

[0063] Alternatively, the polyethylene yarn of the present invention may be manufactured by first winding the multifilament as an undrawn yarn and then drawing the undrawn yarn. That is, the polyethylene yarn of the present invention may be manufactured through a two-step process of first producing an undrawn yarn by melt-spinning polyethylene and then drawing the undrawn yarn.

[0064] If the total draw ratio applied in the drawing process is less than 5, the degree of fiber orientation is low, so the polyethylene yarn cannot have a crystallinity of more than 60%, and it may be difficult to develop strength.

[0065] On the other hand, if the total elongation ratio exceeds 20 times, there is a possibility of yarn breakage, and the strength of the polyethylene yarn ultimately obtained is not suitable, so not only is the weaving property of the polyethylene yarn poor, but the fabric manufactured using the polyethylene yarn is excessively stiff, which may cause discomfort to the user.

[0066] When the linear speed of the first godet roller section (GR1) that determines the spinning speed of the melt spinning of the present invention is determined, the linear speeds of the remaining godet roller sections are appropriately determined so that a total stretching ratio of 5 to 20 times, preferably 8 to 15 times, can be applied to the multifilament in the multi-stage stretching section.

[0067] The multi-stage stretching unit performs multi-stage stretching and heat fixation of the multifilament simultaneously, and the multi-stage stretching multifilament is wound on a winder to complete the polyethylene yarn of the present invention.

[0068] The polyethylene yarn of the present invention, manufactured as described above, exhibits high strength retention, low shrinkage, and excellent heat resistance even when applied at high temperatures, making it suitable for use in articles requiring post-processing. For example, it can be used as a material for general clothing.

[0069] The fabric according to the present invention comprises the polyethylene yarn described above, and since it comprises yarn with improved post-processing properties, it can maintain excellent mechanical properties unique to polyethylene, such as high strength, low shrinkage, coolness, and heat resistance, even when going through fabric manufacturing processes such as knitting and weaving, and thus can be applied to various fields such as safety products, leisure products, daily necessities, or cool-feeling materials.

[0070] In addition, since it includes yarn with improved post-processing properties, the fabric manufactured from it can also maintain mechanical properties even during post-processing such as dyeing or coating.

[0071] Specifically, the fabric according to the present invention may have an abrasion resistance (cycles) of 500 or more, preferably 530 to 700, measured in accordance with ASTM D3884.

[0072] The fabric according to the present invention may be made using the polyethylene yarn described above alone, and may further include different yarns to provide other functionalities. However, from the viewpoint of simultaneously having post-processing properties and cooling sensation, it is preferable to use the polyethylene yarn alone.

[0073] The present invention will be described in more detail based on the following examples and comparative examples. However, the following examples and comparative examples are merely illustrative examples for further explaining the present invention and the present invention is not limited by the following examples and comparative examples.

[0074]

[0075] The properties of polyethylene yarn were measured as follows.

[0076]

[0077] Melting index

[0078] It was measured according to ASTM D1238, the measurement temperature was 190℃, the weight was defined as 2.16kg, and the amount flowing for 10 minutes was measured.

[0079]

[0080] <Weight average molecular weight (Mw) (g / mol) and polydispersity index (PDI)>

[0081] After completely dissolving the polyethylene yarn in the solvent below, the weight average molecular weight (Mw) and polydispersity index (Mw / Mn; PDI) of the polyethylene yarn were obtained using the following gel permeation chromatography (GPC).

[0082] - Analytical instrument: Tosoh HLC-8321 GPC / HT

[0083] - Column: PLgel guard (7.5

[0084] - Column temperature: 160℃

[0085] - Solvent: Trichlorobenzene (TCB) + 0.04 wt% dibutylhydroxytoluene (BHT)

[0086] (after drying with 0.1% CaCl2)

[0087] - Injector, Detector Temperature: 160℃

[0088] - Detector: RI Detector

[0089] - Flow rate: 1.0㎖ / min

[0090] - Injection volume: 300mL

[0091] - Sample concentration: 1.5 mg / mL

[0092] - Standard sample: polystyrene

[0093]

[0094] <Strength (g / d), initial modulus (g / d), and elongation (%)>

[0095] According to ASTM D2256 method, the strain-stress curves of polyethylene yarns were obtained using a universal tensile tester from Instron Engineering Corp., Canton, Mass. The sample length was 250 mm, the tensile speed was 300 mm / min, and the initial load was set to 0.05 g / d. The strength (g / d) and elongation (%) were obtained from the stress and elongation at break, and the initial modulus (g / d) was obtained from the tangent line that gave the maximum slope near the origin of the curve. Five measurements were performed for each yarn, and the average was calculated.

[0096]

[0097] <Strong Measurement>

[0098] The strength (g / d) of polyethylene yarns was measured using a universal tensile tester from Instron Engineering Corp., Canton, Mass., according to ASTM D885. The sample length was 250 mm, the tensile speed was 300 mm / min, and the initial load was set to 0.05 g / d.

[0099] As shown in Fig. 1, after cutting the polyethylene yarn to obtain a sample (200) with a length of 250 mm or more, the sample was passed through a cylindrical glass tube (100) with both ends open, and both ends of the sample were fixed to both ends of the glass tube.

[0100] At this time, no load was applied to the sample. Afterwards, the sample was heated at the test temperature (50℃, 120℃) for 30 minutes using a hot air circulation annular heater, and the strength of the yarn sample was measured. Afterwards, the sample was removed from the heater and slowly cooled to room temperature (20±5℃), and the strength of the yarn sample was measured. The strength was measured five times in total and the average value was calculated.

[0101] Then, the ratio of strength was calculated using the following equation.

[0102] [ceremony ]

[0103] Strength ratio (%) = (Strength of polyethylene yarn at high temperature (B or C)) / (Strength of polyethylene yarn at room temperature (A)) x 100

[0104] In the above formula, the high temperature may be the test temperature, specifically 50°C or 120°C.

[0105]

[0106] <Crystallization degree of yarn>

[0107] 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, and measurements were performed under the following conditions.

[0108] - Light source (X-ray source): Cu-Kα radiation

[0109] - Power: 45kV X 25 mA

[0110] - Mode: Continuous scan mode

[0111] - Scan angle range (2Θ): 10~40˚

[0112] - Scan speed: 0.1˚ / sec

[0113] -Calculation of crystallinity

[0114] Crystallinity (%) = I C / (I A +I C ) x 100

[0115] In the above 2Θ range scanned using XRD, the crystalline region fraction of polyethylene is Ic, and the amorphous region fraction is I A The above crystallinity is expressed as the ratio of the crystalline region fraction to the crystalline and amorphous regions fractions of polyethylene.

[0116]

[0117] <Dry heat shrinkage rate>

[0118] The sample is left in a constant temperature and humidity chamber at 25℃ and 65% relative humidity for 24 hours. After heat shrinkage under no force at 150℃ x 30 minutes, the sample is left in a constant temperature and humidity chamber at 25℃ and 65% relative humidity for 24 hours. The length change before and after yarn shrinkage is shown.

[0119] Shrinkage (%) = (L o -L1) / L0x 100

[0120] L o : After leaving the sample before heat shrinkage in a constant temperature and humidity room at 25℃ and 65% relative humidity for 24 hours, the length of the sample

[0121] L1: After heat shrinkage, the sample was left in a constant temperature and humidity room at 25℃ and 65% relative humidity for 24 hours, and then the length of the sample was measured.

[0122]

[0123] <Wear resistance evaluation>

[0124] The abrasion resistance of knitted fabrics manufactured using polyethylene yarn according to the present invention was measured in accordance with ASTM D3884. A Martindahl abrasion tester was used as the evaluation device. The friction cloth used was 320Cw sandpaper, and the applied load was 1,000 g.

[0125]

[0126] [Example 1]

[0127] Polyethylene yarn containing 240 filaments and having a total fineness of 500 denier was manufactured.

[0128] Specifically, 0.962g / cm 3Polyethylene chips having a density of 100,000 g / mol, a weight-average molecular weight (Mw) of 340,000 g / mol, a polydispersity index (PDI) of 7.5, and a melt index (MI at 190°C) of 1.8 g / 10 min were fed into an extruder and melted. The molten polyethylene was extruded through a die having 240 holes. The ratio of the hole length to the hole diameter of the die, L / D, was 5. The die temperature was 270°C.

[0129] The filaments formed by being discharged from the nozzle holes of the detention were moved to the cooling section and the drawing section. The cooling section and the drawing section each consisted of four sections, and the multifilament yarn was sequentially cooled and drawn. In the first cooling section, it was cooled to 50°C, in the second and third cooling sections, it was cooled to 45°C, and in the fourth cooling section, it was cooled to 40°C. The drawing section consisted of a total of four godet roller sections, and each godet roller section consisted of 1 to 10 godet rollers. The first godet roller section was set to have a maximum temperature of 80°C, the second godet roller section to have a maximum temperature of 90°C, the third godet roller section to have a maximum temperature of 95°C, and the fourth godet roller section to have a maximum temperature of 120°C. The elongation ratio was set to be 2 times elongation in the first godet roller section, 3 times elongation in the second godet roller section, 1.4 times elongation in the third godet roller section, and 4% shrinkage (relaxation) in the fourth godet roller section compared to the third godet roller section, so that the elongation and heat setting were performed at a total elongation ratio of 8 times.

[0130] Next, the above-mentioned elongated multifilament yarn was wound on a winder. The winding tension was 0.8 g / d.

[0131] The physical properties of the manufactured yarn were measured and are shown in Table 1 below.

[0132]

[0133] In addition, the strength (A) of the yarn manufactured at room temperature was measured, and the strength (B) of the manufactured yarn was measured after heat treatment at 120°C for 30 minutes.

[0134] The ratio (B / A) of the strength (B) measured after heat treatment at 120°C for 30 minutes to the strength (A) measured at room temperature and the ratio (C / A) of the strength (C) measured after heat treatment at 50°C for 30 minutes to the strength (A) measured at room temperature were calculated and shown in Table 1.

[0135]

[0136] Fabric manufacturing

[0137] Knitting was performed using the polyethylene yarn manufactured above to produce a knitted fabric. The physical properties of the manufactured knitted fabric were measured and are shown in Table 2 below.

[0138]

[0139] [Examples 2 and 3]

[0140] It was manufactured in the same manner as Example 1 except that the conditions were changed as shown in Table 1 below.

[0141] In addition, the physical properties of the fabric manufactured in the same manner as Example 1 were measured and are shown in Table 2 below.

[0142]

[0143] [Example 4]

[0144] In the above Example 1, the cooling section and the stretching section each consisted of two sections, and specifically, the first cooling section cooled to 50°C, and the second cooling section cooled to 40°C, and the stretching section consisted of a total of two stages of godet roller sections, the maximum temperature of the first godet roller section was set to 80°C, and the maximum temperature of the second godet roller section was set to 120°C, and the stretching ratio was adjusted so that the stretching ratio was 4.4 times in the first godet roller section and 3 times in the second godet roller section, so that the total stretching ratio was 13 times, and the yarn was manufactured in the same manner as in Example 1.

[0145]

[0146] [Example 5]

[0147] In the above Example 1, 0.961 g / cm 3A yarn was manufactured in the same manner as in Example 1, except that polyethylene chips having a density of 340,000 g / mol, a weight average molecular weight (Mw) of 340,000 g / mol, a polydispersity index (PDI) of 5.5, and a melt index (MI at 190°C) of 1.7 g / 10 min were used, and the total draw ratio was adjusted to be 13 times.

[0148]

[0149] [Example 6]

[0150] In the above Example 1, 0.961 g / cm 3 A yarn was manufactured in the same manner as in Example 1, except that polyethylene chips having a density of 10, a weight average molecular weight (Mw) of 340,000 g / mol, a polydispersity index (PDI) of 8, and a melt index (MI at 190°C) of 1.6 g / 10 min were used, and the total draw ratio was adjusted to be 13 times.

[0151]

[0152] [Comparative Example 1]

[0153] In the above Example 1, 0.960 g / cm 3 A yarn was manufactured in the same manner as in Example 1, except that polyethylene chips having a density of 100,000 g / mol, a weight average molecular weight (Mw) of 200,000 g / mol, a polydispersity index (PDI) of 7.5, and a melt index (MI at 190°C) of 5 g / 10 min were used, and the total draw ratio was adjusted to be 11 times.

[0154] In addition, the physical properties of the fabric manufactured in the same manner as Example 1 were measured and are shown in Table 2 below.

[0155]

[0156]

Claims

1. The melting index (MI) measured according to ASTM D1238 is 0.3 to 3 g / 10 min, The ratio (B / A) of the strength (B) measured after heat treatment at 120°C for 30 minutes to the strength (A) measured at room temperature according to ASTM D885 is 85% or more, A polyethylene yarn having a ratio (C / A) of strength (C) measured after heat treatment at 50°C for 30 minutes to strength (A) measured at room temperature of 90% or more.

2. In paragraph 1, The above polyethylene yarn is a polyethylene yarn having a crystallinity of 60 to 85%.

3. In paragraph 1, The above polyethylene yarn is a polyethylene yarn having a crystal size of 200Å or more in a direction parallel to the fiber axis (002 plane) and a crystal size of 110Å or more in a direction perpendicular to the fiber axis (110 plane), as measured by an X-ray diffraction pattern using CuKα rays.

4. In paragraph 1, The above polyethylene yarn is a polyethylene yarn having a melting temperature of 130 to 140°C.

5. In paragraph 1, The above polyethylene yarn has a density of 0.93 to 0.97 g / cm 3 In, polyethylene yarn.

6. In paragraph 1, Polyethylene yarn having a dry heat shrinkage rate of 2.5% or more.

7. In paragraph 1, The above polyethylene yarn is a polyethylene yarn having a tenacity of 1 to 20 g / d as measured according to ASTM D2256.

8. In paragraph 1, The above polyethylene yarn is a polyethylene yarn having a breaking elongation of 20% or less as measured according to ASTM D2256.

9. A fabric comprising a polyethylene yarn according to any one of claims 1 to 8.

10. In paragraph 9, The above fabric is a fabric with an abrasion resistance of 500 or higher.

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