Polyethylene yarn with improved dimensional stability and functional fabric containing the same

Abstract

The present invention relates to a polyethylene raw yarn having improved dimensional stability and a functional fabric containing the same, and more particularly to a polyethylene raw yarn having improved dimensional stability that can prevent deformation during post-processing such as weaving and cutting, and a functional fabric containing the same that can provide a cooling sensation to the user.

Description

[Technical Field]

[0001] The present invention relates to a polyethylene yarn having improved dimensional stability and a functional fabric containing the same, and more particularly to a polyethylene yarn having improved dimensional stability and exhibiting small dimensional deformation during post-processing such as weaving and cutting, and a functional fabric containing the same. [Background technology]

[0002] Recently, due to the improvement of living standards and population growth, the demand for textiles has been shifting from general-purpose yarns for general clothing and industrial fibers to advanced textile materials with high functionality and performance, which have a variety of functions. In particular, there has been active development of textile materials with a cooling effect that provides comfort to users in summer and in high-temperature working environments.

[0003] Cooling fiber materials are imparted with a cooling sensation by utilizing the thermal conductivity of the fiber itself, or by adjusting the thermal conductivity of the surface of the fiber material through coating with a metal component with high thermal conductivity, etc. In particular, cooling fiber materials that utilize the thermal conductivity of the fiber itself can be manufactured through the fabric weaving process alone, and can maintain a cooling sensation even after washing, so they are currently being produced in a variety of industrial fields.

[0004] Conventionally, as disclosed in Japanese Patent Publication JP2010-236130A and Korean Patent Publication No. 10-2017-0135342, attempts have been made to utilize the excellent thermal conductivity of high molecular weight polyethylene (HMWPE) fibers to apply them to a variety of fashion clothing and technical textile fields that require a high cooling sensation, such as sportswear, mountain climbing clothing, and workwear.

[0005] However, this cool-sensing polyethylene yarn contains high-viscosity high-molecular-weight polyethylene, which makes it difficult to manufacture due to the poor melt flow of the raw material. To improve the melt flow of the raw material, the raw material containing high-viscosity high-molecular-weight polyethylene is diluted with a solvent to produce the yarn, but this process becomes complicated, and additional problems arise, such as difficulty in managing and recovering the solvent.

[0006] On the other hand, compared to high-viscosity high-molecular-weight polyethylene fibers, low-viscosity low-molecular-weight polyethylene fibers have the disadvantage of being disadvantageous in post-processing such as weaving, knitting, and heat treatment due to their low strength, high elongation, and poor dimensional stability. Therefore, low-molecular-weight polyethylene fibers have lower industrial applicability than high-molecular-weight polyethylene fibers, and are not utilized in a variety of applications. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a polyethylene raw yarn that exhibits a small dimensional deformation rate and improved dimensional stability during post-processing such as weaving and cutting, and a functional fabric that contains the same and can provide a cooling sensation to the user. [Means for solving the problem]

[0008] The polyethylene yarn according to the present invention has a maximum thermal shrinkage stress of 0.1 to 0.7 g / d and a melt index (MI, at 190° C.) of 5 to 25 g / 10 min.

[0009] In the polyethylene yarn according to one embodiment of the present invention, the yarn may have a polydispersity index (PDI) of 5 to 20 and a number average molecular weight (Mn) of 1,000 to 10,000 g / mol.

[0010] In the polyethylene yarn according to one embodiment of the present invention, the yarn may have a tenacity of 6 to 17 g / d and an elongation of 10 to 25%, as measured according to ASTM D2256.

[0011] In the polyethylene yarn according to one embodiment of the present invention, the yarn may have a crystallinity of 65 to 85%.

[0012] In one embodiment of the present invention, the polyethylene yarn has a density of 0.92 to 0.97 g / cm 3 may be.

[0013] The functional fabric according to the present invention comprises the polyethylene yarn described above.

[0014] In one embodiment of the functional fabric according to the present invention, the fabric has a cooling sensation of 0.05 to 0.25 W / cm, measured by contacting a 30±2°C hot plate (T-box) with the fabric at 20±2°C at 20±2°C and 65±2% RH. 2 It could be.

[0015] In the functional fabric according to one embodiment of the present invention, the fabric may have a thickness-wise thermal conductivity of 0.05 to 0.25 W / mK, measured at 20±2°C and 65±2% RH by contacting a heat source plate (BT-box) at 30±2°C with the fabric at 20±2°C.

[0016] In one embodiment of the functional fabric according to the present invention, the fabric has a surface density of 150 to 800 g / m 2 may be.

[0017] The cooling product according to the present invention is made from the above-mentioned fabric. [Effects of the Invention]

[0018] The polyethylene yarn according to the present invention has excellent dimensional stability and excellent thermal conductivity, despite being a low-molecular-weight polyethylene yarn.

[0019] In addition, the functional fabric according to the present invention contains polyethylene yarn having excellent thermal conductivity and high dimensional stability, so that it has a cool feeling and is prevented from deforming during post-processing, thereby providing excellent quality. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram illustrating a polyethylene yarn manufacturing apparatus. [Figure 2] FIG. 1 is a schematic diagram showing an apparatus for measuring the cool touch feeling of fabric. [Figure 3] FIG. 1 is a schematic diagram illustrating an apparatus for measuring the thermal conductivity of a fabric in the thickness direction. [Figure 4] 1 is a graph showing the heat shrinkage stress of the fabric according to Example 1. [Figure 5] 1 is a graph showing the heat shrinkage stress of the fabric according to Example 7. DETAILED DESCRIPTION OF THE INVENTION

[0021] Unless otherwise defined, the technical and scientific terms used in this specification have the meanings that are commonly understood by those with ordinary knowledge in the technical field to which this invention belongs, and descriptions of known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted in the following description and accompanying drawings.

[0022] Also, as used herein, the singular forms "a," "an," and "the" can be intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0023] Furthermore, units used in this specification without any special mention are based on weight, and for example, the unit of % or ratio means % by weight or weight ratio, and unless otherwise defined, % by weight means the weight % of any one component in a total composition.

[0024] Furthermore, the numerical ranges used herein include the lower and upper limits, all values ​​within the range, logically derived increments in the form and width of the defined range, all limited values ​​therein, and all possible combinations of upper and lower limits for numerical ranges limited in different forms. Unless otherwise specified in the specification of the present invention, values ​​outside the numerical range that may occur due to experimental error or rounding of values ​​are also included in the defined numerical range.

[0025] As used herein, the term 'comprising' is an open-ended term that has the same meaning as terms such as 'comprising,' 'containing,' 'having,' or 'featuring,' and does not exclude additional, unrecited elements, materials, or steps.

[0026] Conventional cool-feeling polyethylene yarns contain high-viscosity high-molecular-weight polyethylene, which makes them difficult to manufacture due to the poor melt flow of the raw material. To improve the melt flow of the polyethylene yarn raw material, the raw material containing high-viscosity high-molecular-weight polyethylene was diluted with a solvent to produce the yarn, but this process became complicated and created additional problems such as difficulty in managing and recovering the solvent.

[0027] On the other hand, compared to high-viscosity high-molecular-weight polyethylene yarn, low-viscosity low-molecular-weight polyethylene yarn has the disadvantage of being disadvantageous in post-processing such as weaving, knitting, and heat treatment due to its low strength, high elongation, and poor dimensional stability. Therefore, low-molecular-weight polyethylene yarn has lower industrial applicability than high-molecular-weight polyethylene yarn and is not used in a variety of applications.

[0028] Therefore, the present applicant has developed a polyethylene yarn that contains low-viscosity low-molecular-weight polyethylene but has high dimensional stability. This allows for easy spinning due to the inherent high melt flow properties of polyethylene, without the need for dilution with a separate solvent, and provides a polyethylene yarn that has excellent dimensional stability and mechanical properties with little dimensional deformation during post-processing such as weaving, cutting, and dyeing.

[0029] In this specification, polyethylene raw yarn refers to monofilament or multifilament manufactured from polyethylene chips through processes such as spinning and drawing. For example, the polyethylene fiber may include 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.

[0030] The polyethylene yarn of the present invention has a maximum thermal shrinkage stress of 0.1 to 0.7 g / d and a melt index (MI, at 190°C) of 5 to 10 g / 10 min. Despite containing low-viscosity, low-molecular-weight polyethylene, it exhibits excellent heat shrinkage, i.e., excellent dimensional stability. Therefore, unlike when containing high-viscosity, high-molecular-weight polyethylene, the spinning process does not require dilution with a separate solvent, simplifying the process and resulting in high yarn productivity. It also maintains excellent thermal conductivity without deformation during post-processing such as weaving and twisting. Furthermore, its excellent thermal conductivity and dimensional stability enable it to be used in fabrics with excellent physical properties, such as a cooling sensation.

[0031] The dimensional stability of the polyethylene yarn according to the present invention refers to the property of resisting dimensional deformation due to heat, pressure, tension, etc. when the yarn is subjected to post-processing such as weaving or knitting into fabric, and may also refer to shape stability. The higher the dimensional stability, the smaller the dimensional deformation rate during post-processing.

[0032] The cooling sensation of fabrics containing polyethylene yarns according to the present invention is a characteristic that allows users wearing the fabric to feel an appropriate cooling sensation, i.e., a cooling feeling, due to the high thermal conductivity of the yarns. Specifically, in the case of polymers, heat is transferred within the polymer (particularly in the direction of molecular chains connected through covalent bonds) primarily through lattice vibrations called phonons. In other words, the thermal conductivity of yarns can be adjusted to differ depending on the structural characteristics of the polymer itself, such as the degree of crystallinity and orientation of the yarns, even for yarns made from the same resin.

[0033] As described above, the polyethylene yarn may have a maximum heat shrinkage stress of 0.1 to 0.7 g / d, specifically 0.2 to 0.5 g / d, and a melt index (MI, at 190°C) of 5 to 25 g / 10 min, specifically 6 to 15 g / 10 min, but is not limited thereto. However, within these ranges, the polyethylene yarn may have better dimensional stability and thermal conductivity. Furthermore, such polyethylene yarn has a low viscosity when melted, allowing it to be spun without the need for a separate solvent during the spinning process, resulting in excellent spinning efficiency.

[0034] In particular, the polyethylene yarn may contain low-molecular-weight polyethylene and have a polydispersity index (PDI) of 5 to 20, specifically 8 to 18, and more specifically 10 to 15, and a number-average molecular weight (Mn) of 1,000 to 10,000 g / mol, specifically 2,000 to 5,000 g / mol. Polyethylene yarns with a polydispersity index and number-average molecular weight within these ranges ensure good melt flow during melt extrusion, prevent thermal decomposition, and ensure processability, such as preventing yarn breakage during drawing. This allows for the production of yarns with uniform physical properties and excellent durability. The weight-average molecular weight is not limited as long as it satisfies the PDI value for the number-average molecular weight, but it may be lower than that of conventional polyethylene yarns for cooling sensations. Specifically, the weight-average molecular weight may be 20,000 to 90,000 g / mol, specifically 35,000 to 75,000 g / mol.

[0035] In addition, polyethylene yarn has a density of 0.92 to 0.97 g / cm 3 The crystallinity of the polyethylene yarn may be 60 to 90%, specifically 65 to 85%, after spinning. The crystallinity of the polyethylene yarn can be determined together with the size of the crystallites through crystallinity analysis using an X-ray diffraction analyzer. As described above, when the crystallinity satisfies the above range, heat is rapidly diffused and dissipated through lattice vibrations called 'phonons' in the direction of the molecular chains connected through covalent bonds of the polyethylene, improving the ability to expel moisture such as sweat and breath, thereby providing a fabric with an excellent cooling sensation.

[0036] The polyethylene yarn may have a strength of 6 to 17 g / d, specifically 10 to 15 g / d, and an elongation of 10 to 25%, specifically 12 to 20%, as measured according to ASTM D2256. Polyethylene yarn having a strength and elongation within these ranges not only has excellent thermal conductivity, but also relatively high flexibility and excellent weavability, so that when it is later woven into fabric, a fabric of better quality can be obtained.

[0037] A method for producing a polyethylene yarn according to one embodiment of the present invention will be described in detail below with reference to Figure 1. The polyethylene yarn of the present invention is not limited to any particular method for producing it as long as it satisfies the ranges of the physical properties such as PDI, strength, and elongation, and the following description will be limited to one embodiment.

[0038] First, polyethylene chips are fed into an extruder 100 and melted to obtain a polyethylene melt.

[0039] Molten polyethylene is transported through the die 100 by a screw (not shown) in the extruder 100 and extruded through a number of holes formed in the die 200. The number of holes in the die 200 can be determined depending on the DPF (Denier Per Filament) and fineness of the yarn to be produced. For example, when producing a yarn having a total fineness of 75 denier, the die 200 may have 20 to 75 holes, and when producing a yarn having a total fineness of 450 denier, the die 200 may have 90 to 450 holes, preferably 100 to 400 holes.

[0040] The melting process in the extruder 100 and the extrusion process through the die 200 can be changed and applied depending on the melt index of the polyethylene chips, but specifically, for example, they are preferably performed at 150 to 315°C, preferably 250 to 315°C, and more preferably 265 to 310°C. That is, it is preferable that the extruder 100 and the die 200 are maintained at 150 to 315°C, preferably 250 to 315°C, and more preferably 265 to 310°C.

[0041] If the spinning temperature is less than 150°C, the polyethylene may not be uniformly melted, making spinning difficult. On the other hand, if the spinning temperature exceeds 315°C, the polyethylene may be thermally decomposed, making it difficult to achieve the desired strength.

[0042] The ratio L / D, which is the ratio of the hole length L to the hole diameter D in the spinneret 200, may be 3 to 40. If L / D is less than 3, a die swell phenomenon occurs during melt extrusion, making it difficult to control the elastic behavior of the polyethylene, resulting in poor spinnability. If L / D exceeds 40, thread breakage due to necking of the molten polyethylene passing through the spinneret 200 and non-uniform extrusion due to a drop in pressure may occur.

[0043] As the molten polyethylene is extruded from the holes of the spinneret 200, the difference between the spinning temperature and room temperature causes the polyethylene to begin to solidify, forming semi-solid filaments 11. In this specification, both semi-solidified filaments and fully solidified filaments are collectively referred to as "filaments."

[0044] The filaments 11 are completely solidified by being cooled in a cooling section (or "quenching zone") 300. The filaments 11 can be cooled by air cooling.

[0045] The cooling of the filaments 11 in the cooling unit 300 is preferably performed using cooling air at a speed of 0.2 to 1 m / sec to cool the filaments 11 to 15 to 40° C. If the cooling temperature is less than 15° C., the filaments 11 may be overcooled, resulting in insufficient elongation, and may break during the drawing process. If the cooling temperature exceeds 40° C., the filaments 11 may be solidified non-uniformly, resulting in a large deviation in fineness, and may break during the drawing process.

[0046] Furthermore, by performing multi-stage cooling in the cooling section, crystallization can be more uniform, which allows for smoother discharge of moisture and sweat and allows for the production of yarn with an excellent cooling sensation. More specifically, the cooling section may be divided into two or more sections. For example, when it consists of two cooling sections, it is preferable that the temperature is designed to gradually decrease from the first cooling section to the second cooling section. Specifically, for example, the first cooling section may be set to 40 to 90°C, and the second cooling section may be set to 15 to 50°C.

[0047] Furthermore, by setting the air velocity in the first cooling section to the highest, it is possible to produce fibers with a smoother surface. Specifically, the first cooling section may use cooling air at a velocity of 0.8 to 1.2 m / sec to cool to 40 to 90°C, and the second cooling section may use cooling air at a velocity of 0.3 to 1.0 m / sec to cool to 15 to 50°C. By adjusting the conditions in this way, it is possible to produce raw yarn with a higher crystallinity and a smoother surface.

[0048] Next, the cooled and completely solidified filaments 11 are bundled in a bundler 400 to form a multifilament 10.

[0049] As illustrated in Figure 1, the polyethylene raw yarn of the present invention can be produced through a direct spin-draw (DSD) process. That is, the multifilament 10 is directly conveyed to a multi-stage drawing section 500 including a plurality of godet roller sections GR1...GRn, where it is multi-stage drawn at a total draw ratio of 2 to 20 times, preferably 3 to 15 times, and then wound on a winder 600. In addition, during the multi-stage drawing, a shrinkage draw (relaxation) of 1 to 5% is imparted in the final drawing section, thereby providing a raw yarn with superior durability.

[0050] Alternatively, the polyethylene raw yarn of the present invention can be produced by first winding the multifilament 10 as an undrawn yarn and then drawing the undrawn yarn. That is, the polyethylene raw yarn of the present invention can be produced through a two-step process of first producing an undrawn yarn by melt-spinning polyethylene and then drawing the undrawn yarn.

[0051] If the total draw ratio applied in the drawing process is less than 2, the final polyethylene yarn cannot have a crystallinity of 60% or more, and there is a risk of feathering (filling) being induced on the fabric produced from the yarn.

[0052] On the other hand, if the total draw ratio exceeds 15 times, yarn breakage may occur, and the strength of the finally obtained polyethylene yarn may not be adequate, resulting in poor weaving properties of the polyethylene yarn and fabrics made therefrom that may be too stiff, causing inconvenience to users.

[0053] Once the linear speed of the first godet roller unit GR1, which determines the spinning speed of the melt spinning of the present invention, is determined, the linear speeds of the remaining godet roller units are appropriately determined so that a total draw ratio of 2 to 20, preferably 3 to 15, is applied to the multifilament 10 in the multi-stage drawing unit 500.

[0054] According to one embodiment of the present invention, the temperatures of the godet roller units GR1...GRn of the multi-stage drawing unit 500 are appropriately set in the range of 40 to 140°C, thereby heat-setting the polyethylene yarn through the multi-stage drawing unit 500. Specifically, for example, the multi-stage drawing unit may be composed of three or more drawing sections, specifically, three to five drawing sections. Furthermore, each drawing section may be composed of a plurality of godet roller units.

[0055] Specifically, the multi-stage drawing section may comprise four drawing sections, in which the fiber is drawn to a total draw ratio of 7 to 15 times in the first to third drawing sections, and then contracted and drawn (relaxed) by 1 to 3% in the fourth drawing section. The total draw ratio refers to the final draw ratio of the fiber after the first to third drawing sections compared to the fiber before drawing.

[0056] More specifically, the first stretching section may be performed at 40 to 120°C, with a total stretch ratio of 2 to 5. The second stretching section may be performed at a higher temperature than the first stretching section, specifically at 90 to 140°C, with stretching to a total stretch ratio of 5 to 8. The third stretching section may be performed at 90 to 140°C, with stretching to a total stretch ratio of 7 to 15. The fourth stretching section may be performed at the same or lower temperature as the third stretching section, specifically at 90 to 140°C, with 1 to 3% shrinkage and stretching (relaxation).

[0057] The multistage drawing section 500 simultaneously performs multistage drawing and heat setting of the multifilament 10, and the multistage drawn multifilament 10 is wound on a winder 600 to complete the polyethylene raw yarn of the present invention.

[0058] The functional fabric according to the present invention contains the polyethylene yarn described above, which has excellent thermal conductivity and dimensional stability, and thus can have cooling properties and excellent quality.

[0059] The functional fabric according to the present invention may be made using the polyethylene yarn alone, or may further contain a different type of yarn to impart other functionality. However, from the viewpoint of simultaneously providing a cool feeling and dimensional stability, it is preferable to use the polyethylene yarn alone.

[0060] Specifically, the functional fabric can have excellent cooling sensation by containing the above-mentioned raw yarn. Specifically, the cooling sensation measured by contacting a 20±2°C fabric with a 30±2°C hot plate (T-box) at 20±2°C and 65±2% RH is 0.05 to 0.25 W / cm. 2 The thermal conductivity in the thickness direction measured by contacting a 30±2°C heat source plate (BT-box) with a 20±2°C fabric at 20±2°C and 65±2% RH can be 0.05~0.25W / mK. More specifically, the cool touch sensation is 0.07~0.20W / cm 2 The thermal conductivity in the thickness direction can be 0.07 to 0.20 W / mK. When this functional fabric with a cooling sensation is later manufactured or processed into a product and worn by a user, it can provide an appropriate cooling sensation that allows the user to feel comfortable in a high-temperature environment.

[0061] Furthermore, the functional fabric can have excellent dimensional stability by including the polyethylene yarn. Specifically, when the functional fabric is woven or knitted using the polyethylene yarn, the dimensional deformation rate of the final fabric relative to the designed dimensions is almost zero, resulting in almost no defective products and excellent quality.

[0062] Furthermore, by including a raw yarn having a specific heat shrinkage stress as described above, the functional fabric can have excellent dimensional stability even under harsh conditions at high temperatures. Specifically, under conditions of 90±2°C and 65±2% RH, the dimensional deformation rate of the fabric expressed by the following formula 1 can be -2.0% to 2.0%, preferably -1.8% to 1.8%, and more preferably -1.5% to 1.5%.

[0063] [Formula 1] Dimensional deformation rate (%) = {(FS1-FS0) / (FS0)} x 100

[0064] (In the above formula, FS0 is the dimension (mm) of the functional fabric measured after leaving it at room temperature (20±2°C, 65±2% RH) for 24 hours, and FS1 is the dimension (mm) of the functional fabric measured after leaving it at 90±2°C, 65±2% RH for 24 hours.)

[0065] In this way, functional fabrics have excellent dimensional stability even under harsh conditions, ensuring dimensional stability during post-processing when various external forces such as heat and pressure act on them, thereby providing excellent post-processability.

[0066] In addition, functional fabrics are available in a range of 150 to 800 g / m 2 The fabric may be a woven or knitted fabric having a weight per unit area (i.e., areal density) of 150 g / m. 2 If the surface density of the fabric is less than 800 g / m, the fabric will not be dense enough and many voids will be present in the fabric, which will reduce the cooling sensation of the fabric. 2 If it exceeds this value, the excessively dense fabric structure will make the fabric stiff, causing problems with the feel felt by the user, and the high weight will cause problems in use.

[0067] Such fabrics can be processed into cooling products that require a suitable cooling sensation. The products can be any conventional textile products, but are preferably summer clothes, sportswear, masks, and workwear that provide a cooling sensation to the human body.

[0068] The present invention will be described in more detail with reference to the following examples, but the following examples are merely a reference for explaining the present invention in detail and are not intended to limit the scope of the present invention, which may be embodied in various forms.

[0069] Furthermore, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used in the description of this application are merely for the purpose of effectively describing specific examples and are not intended to limit the present invention. Furthermore, the unit of additives not specifically described in the specification may be % by weight. [Example]

[0070] The physical properties were measured as follows.

[0071] [Measurement of yarn physical properties] <1. Thermal shrinkage stress> A loop-shaped sample was made by tying both ends of a polyethylene yarn, and then both ends of the loop-shaped sample were placed in the hot chamber of a thermal stress tester (Kanebo Eng., Japan, KE-2). The loop sample was then hooked on both sides to a load cell and a preload ring, and the maximum thermal shrinkage stress was measured under the following conditions: The circumference of the loop was 10 cm.

[0072] -Load cell: A load cell that can measure up to 500gf -Initial temperature: room temperature (20±2℃) - Heating rate: 300℃ / 120sec -Initial load: 0.06667g / d

[0073] The thermal shrinkage stress values ​​were obtained as a graph through an output device (Type 3086 XT Recorder, Yokogawa, Hokushin Electric, Tokyo, Japan).

[0074] 2. Number average molecular weight (Mw) (g / mol), weight average molecular weight (Mw) (g / mol) and polydispersity index (PDI) The polyethylene yarn was completely dissolved in the following solvent, and then the weight average molecular weight (Mw) and polydispersity index (Mw / Mn: PDI) of the polyethylene yarn were determined using the following gel permeation chromatography (GPC).

[0075] -Analytical equipment: Tosoh HLC-8321 GPC / HT -Column: PLgel guard (7.5 x 50 mm) + 2 x PLgel mixed-B (7.5 x 300 mm) -Column temperature: 160℃ -Solvent: Trichlorobenzene (TCB) + 0.04 wt.% dibutylhydroxytoluene (BHT) (after drying with 0.1% CaCl2) -Injector, Detector temperature: 160℃ -Detector:RI Detector -Flow rate: 1.0ml / min -Injection volume: 300mL -Sample concentration: 1.5mg / mL -Standard sample: polystyrene

[0076] <3. Strength (g / d) and elongation (%)> Deformation-stress curves of polyethylene yarns were obtained using a universal tensile tester manufactured by Instron Engineering Corp. (Canton, Mass.) according to ASTM D2256. The sample length was 250 mm, the tensile speed was 300 mm / min, and the initial load was set at 0.05 g / d. The strength (g / d) and elongation (%) were calculated from the stress and elongation at the break point, and the initial modulus (g / d) was calculated from the tangent line that gave the maximum slope near the origin of the curve. Five measurements were taken for each yarn, and the average value was calculated.

[0077] <4. Crystallinity> The crystallinity of the polyethylene yarn was measured using an X-ray Diffractometer (XRD) [manufacturer: PANalytical, model name: EMPYREAN]. Specifically, the polyethylene yarn was cut to prepare a sample having a length of 2.5 cm, and the sample was fixed to a sample holder and then measured under the following conditions.

[0078] -Light source (X-ray Source):Cu-Kα radiation -Power: 45KV x 25mA - Mode: Continuous scan mode -Scan angle range: 10~40° -Scanning speed: 0.1° / sec

[0079] [Measurement of fabric properties] <1. Cool sensation to the touch> The measurements were conducted at the Korea Clothing Testing and Research Institute using a KES-F7 (Thermo Labo II) device in a test environment of 20±2°C and 65±2% RH.

[0080] Specifically, a 20cm x 20cm fabric sample was prepared and left for 24 hours under conditions of 20±2°C temperature and 65±2% RH. The fabric's coolness to the touch (Q max) was then measured using a KES-F7 THERMO LABO II (Kato Tech Co., Ltd.) device in a test environment of 20±2°C temperature and 65±2% RH. Specifically, as illustrated in Figure 2, the fabric sample 23 was placed on a base plate (also called a 'Water-Box') 21 maintained at 20°C, and a hot plate (T-Box) 22a (contact area: 3cm x 3cm) heated to 30°C was placed on the fabric sample 23 for only 1 second. That is, one side of the fabric sample 23, which was in contact with the base plate 21, was momentarily brought into contact with the T-Box 22a. The contact pressure applied to the fabric sample 23 by the T-Box 22a was 6gf / cm. 2The Qmax value displayed on a monitor (not shown) connected to the device was then recorded. This test was repeated 10 times, and the arithmetic mean of the Qmax values ​​was calculated.

[0081] <2. Thermal conductivity> A 20cm x 20cm dough sample was prepared and left for 24 hours under conditions of 20±2°C and 65±2% RH. The thermal conductivity and heat transfer coefficient of the dough were then measured using a KES-F7 THERMO LABO II (Kato Tech Co., Ltd.) device under the test conditions of 20±2°C and 65±2% RH. Specifically, as illustrated in FIG. 3, the dough sample 23 was placed on a base plate 21 maintained at 20°C, and a BT-Box 22b (contact area: 5cm x 5cm) heated to 30°C was placed on the dough sample 23 for 1 minute. Heat was continuously supplied to the BT-Box 22b while in contact with the dough sample 23 to maintain its temperature at 30°C. The amount of heat supplied to maintain the temperature of the BT-Box 22b (i.e., heat flow loss) was displayed on a monitor (not shown) connected to the device. This test was repeated five times, and the arithmetic mean of the heat flow loss was calculated.The thermal conductivity and heat transfer coefficient of the fabric were then calculated using Equations 2 and 3 below.

[0082] [Equation 2]: K = (WD) / (A.ΔT) [Formula 3]:k=K / D

[0083] Here, K is the thermal conductivity (W / cm.°C), D is the thickness (cm) of the fabric sample 23, and A is the contact area of ​​the BT-Box 22b (=25 cm 2 ), ΔT is the temperature difference between the two surfaces of the fabric sample 23 (=10°C), W is the heat flow loss (Watt), and k is the heat transfer coefficient (W / cm 2 .℃).

[0084] 3. Dimensional stability After preparing a fabric sample measuring 20 cm x 20 cm, it was left for 24 hours under conditions of a temperature of 20 ± 2 ° C and a relative humidity of 65 ± 2%. After that, the dimensions of one edge of the fabric sample were measured.

[0085] After that, the fabric was left for 24 hours under the conditions of 90±2°C temperature and 65±2% RH, and the dimensions were measured again using the same method. The dimensional deformation rate of the fabric was then calculated using the following formula 1.

[0086] [Formula 1] Dimensional deformation rate (%) = {(FS1-FS0) / (FS0)} x 100

[0087] (In the above formula, FS0 is the dimension (mm) of the functional fabric measured after weaving and leaving it at room temperature (20±2°C, 65±2% RH) for 24 hours, and FS1 is the dimension (mm) of the functional fabric measured after weaving and leaving it at 90±2°C, 65±2% RH for 24 hours.)

[0088] [Example 1] <Production of polyethylene yarn> Using the apparatus illustrated in FIG. 1, a polyethylene yarn containing 200 filaments and having a total fineness of 400 denier was produced.

[0089] First, 0.93 g / cm 3 Polyethylene chips having a density of 1000 kJ / mol and a weight average molecular weight (Mw) of 8,500 g / mol were fed into an extruder 100 and melted. The molten polyethylene was extruded through a die 200 having 200 holes. The ratio of the hole length (L) to the hole diameter (D) in the die 200, L / D, was 6. The die temperature was 270°C.

[0090] The filaments 11 formed while being discharged from the nozzle holes of the spinneret 200 were sequentially cooled in the cooling section 300, which consisted of two sections. In the first cooling section, they were cooled to 60°C by cooling air at a speed of 1.0 m / sec, and in the second cooling section, they were finally cooled to 30°C by cooling air at a speed of 0.5 m / sec. After being cooled, they were bundled into a multifilament yarn 10 by a bundler 400.

[0091] The multifilament yarn was then transferred to the drawing section 500. The drawing section was a multi-stage drawing section consisting of four sections, and was composed of a total of four godet roller sections, each consisting of two to six godet rollers.

[0092] Specifically, in the first stretching section, the film was stretched to a total stretch ratio of 2 times at a maximum stretching temperature of 80°C, in the second stretching section, the film was stretched to a total stretch ratio of 1.5 times at a maximum stretching temperature of 120°C, in the third stretching section, the film was stretched to a total stretch ratio of 1.3 times at a maximum stretching temperature of 120°C, and in the fourth stretching section, the film was stretched and heat-set at a maximum stretching temperature of 120°C so as to be shrunk (relaxed) by 2% compared to the third stretching section.

[0093] The drawn multifilament yarn was then wound on a winder 600. The winding tension was 0.8 g / d.

[0094] The physical properties of the produced yarn were measured and are shown in Table 1 below.

[0095] The measured heat shrinkage stress graph is shown in FIG.

[0096] <Manufacturing of functional fabrics> The polyethylene yarn thus produced was woven to a surface density of 500 g / m 2 The physical properties of the functional fabric were measured and are shown in Table 3 below.

[0097] [Examples 2 to 9] Fabrics were manufactured in the same manner as in Example 1, except that the raw yarn conditions were changed as shown in Table 1 below. The physical properties of the fabrics manufactured in the same manner as in Example 1 were measured and are shown in Table 3 below. The measured heat shrinkage stress graph for Example 7 is shown in Figure 5.

[0098] [Comparative Examples 1 to 2] Fabrics were manufactured in the same manner as in Example 1, except that the raw yarn conditions were changed as shown in Table 2 below. In addition, the physical properties of the fabrics manufactured in the same manner as in Example 1 were measured and are shown in Table 4 below.

[0099] Comparative Example 3 The yarn and fabric were manufactured in the same manner as in Example 1, except that the yarn conditions were changed and the number of drawing sections was set to 2 as shown in Table 2 below. In addition, the physical properties of the fabric manufactured in the same manner as in Example 1 were measured and are shown in Table 4 below.

[0100] Comparative Example 4 The yarn and fabric were manufactured in the same manner as in Example 1, except that the yarn conditions were changed and the number of drawing sections was set to 6 as shown in Table 2 below. In addition, the physical properties of the fabric manufactured in the same manner as in Example 1 were measured and are shown in Table 4 below.

[0101] [Table 1]

[0102] [Table 2]

[0103] [Table 3]

[0104] [Table 4]

[0105] Referring to Tables 1 to 4 above, it was confirmed that the fabrics according to the examples had an appropriate cool feeling and excellent dimensional stability. In particular, in the case of Comparative Example 4, although the fabric was manufactured using a raw yarn with a relatively high degree of crystallinity, a large amount of fluff was generated during the manufacturing of the fabric, resulting in low cool feeling and thermal conductivity.

[0106] As described above, the present invention has been described using specific details and limited examples and drawings, but these are provided merely to assist in a more general understanding of the present invention, and the present invention is not limited to the above examples. Those skilled in the art will appreciate that various modifications and variations can be made from such descriptions.

[0107] Therefore, the concept of the present invention should not be limited to the described embodiments, and all aspects that are equivalent or have equivalent modifications to the scope of the claims, as well as the scope of the claims, should be considered to fall within the scope of the concept of the present invention. [Explanation of symbols]

[0108] 10: Multifilament 11: Filament 21: Base plate 23: Fabric 22a:T-box 22b:BT-box 100: Extruder 200: nozzle 300: Cooling section 400:Focusing part 500: Stretching part 600: Winder

Claims

1. A number average molecular weight (Mn) of 1,000 to 10,000 g / mol, The maximum thermal shrinkage stress is 0.1 to 0.7 g / d; A polyethylene raw yarn having a melt index (MI, @190°C) of 5 to 25 g / 10 min.

2. The polyethylene yarn according to claim 1, wherein the yarn has a polydispersity index (PDI) of 5 to 20.

3. 2. The polyethylene yarn according to claim 1, wherein the yarn has a tenacity of 6 to 17 g / d and an elongation of 10 to 25%, as measured in accordance with ASTM D2256.

4. 2. The polyethylene yarn according to claim 1, wherein the yarn has a crystallinity of 65 to 85%.

5. The raw yarn has a density of 0.92 to 0.97 g / cm ３ The polyethylene fiber according to claim 1,

6. The polyethylene yarn according to any one of claims 1 to 5 is included, Functional fabric having a dimensional deformation rate of -1.8% to 1.8% expressed by the following formula 1: [Formula 1] Dimensional deformation rate (%)={(FS 1 −FS 0 ) / (FS 0 )}×100 In the above formula, FS 0 is the dimension (mm) of the functional fabric measured after leaving it at room temperature (20±2°C, 65±2% RH) for 24 hours, and FS 1 is the dimension (mm) of the functional fabric measured after leaving it under conditions of 90±2°C, 65±2% RH for 24 hours.

7. The fabric has a cooling sensation of 0.05 to 0.25 W / cm when measured at 20±2°C and 65±2% RH by contacting a 30±2°C hot plate (T-box) with the fabric at 20±2°C. ２ The functional fabric according to claim 6,

8. The functional fabric according to claim 6, wherein the fabric has a thickness direction thermal conductivity of 0.05 to 0.25 W / mK, measured at 20±2°C and 65±2% RH by contacting a heat source plate (BT-box) at 30±2°C with the fabric at 20±2°C.

9. The fabric has a surface density of 150 to 800 g / m ２ The functional fabric according to claim 6,

10. A cooling product made from the fabric of claim 6.

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