Cooling polyethylene fabric

Abstract

The present invention discloses a cooling polyethylene fabric which has Q-max value of 0.3 W / cm2 or grater and luxurious feel, and which exhibits UV-blocking effect as well as regulating increase in pack pressure and reducing frequency of yarn breakage during yarn production to thus increase productivity during production.

Description

polyethylene cooling fabric

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

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0089935, filed July 8, 2024, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a polyethylene cooling fabric.

[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 a variety of materials. Among these, the development of contact cooling fabrics using polyethylene fibers, as described in Patent Documents 1 and 2, is rapidly growing. Contact cooling fabrics made of polyethylene provide an immediate cooling effect, but cannot be expected to provide any other functional benefits beyond the aforementioned cooling effect.

[0008] Recently, functional fabrics have been proposed to provide not only a cooling sensation but also various functions.

[0009] Patent Documents 3 and 4 propose methods for improving cooling performance while exhibiting other physical properties. Specifically, Patent Documents 3 and 4 propose a cooling fabric that improves cooling performance by controlling the number-average molecular weight (Mn) and Z-average molecular weight (Mz). Patent Document 3 also proposes a cooling fabric that adds pigments to enhance color clarity, while Patent Document 4 proposes a cooling fabric that adds antibacterial properties by incorporating an antibacterial agent. These patents reveal that additives such as pigments and antibacterial agents affect the yarn spinning process, resulting in a deterioration in the physical properties of the yarn and fabric, particularly the cooling performance.

[0010] Therefore, the development of new technologies that can secure functionality without affecting the cooling function of cooling fabrics is required.

[0011] [Prior Art Literature]

[0012] (Patent Document 1) KR Registered Patent No. 10-2137243 (Announced on July 23, 2020)

[0013] (Patent Document 2) KR Registered Patent No. 10-2183247 (Announced on November 26, 2020)

[0014] (Patent Document 3) KR Registered Patent No. 10-2666243 (Announced on May 16, 2024)

[0015] (Patent Document 4) KR Registered Patent No. 10-2666244 (Announced on May 16, 2024)

[0016] The applicant has continuously conducted research on a cooling fabric using polyethylene to secure new functionality as well as a sufficient level of cooling functionality when applied to the human body.

[0017] Titanium dioxide possesses inherent matte and UV-blocking properties. Therefore, incorporating titanium dioxide into fabrics can enhance the fabric's luxurious feel and ensure UV-blocking effects due to its matte properties. However, the addition of titanium dioxide increases the pack pressure during the spinning process for yarn production and causes yarn breakage, which reduces the physical properties of the final yarn and the cooling properties of the cool-touch fabric made from this yarn.

[0018] The present invention provides a technology that can control the content of titanium dioxide in the production process of polyethylene yarn to impart new functionality, thereby suppressing an increase in pack pressure during the spinning process and reducing yarn breakage of unstretched yarn, thereby obtaining a luxurious feel and UV-blocking effect of the fabric without affecting the physical properties such as strength and elongation, including the cooling function of the cooling fabric.

[0019] The present invention relates to a polyethylene cooling fabric manufactured from polyethylene yarn, wherein the polyethylene yarn contains 0.2 to 0.7 wt% of titanium dioxide based on the total weight thereof, and the polyethylene cooling fabric has a contact cooling (Qmax, average value after a total of 5 measurements) value of 0.3 W / cm, which is measured by contacting a hot plate (T-box) of 40±2℃ with a fabric of 20±2℃ at 20±2℃ and 65±4% relative humidity. 2 We provide ideal polyethylene cooling fabric.

[0020] The polyethylene cooling fabric of the present invention has a thermal conductivity of 0.3 W / cm 2 A contact cooling fabric with a Qmax value above provides an immediate cooling effect upon contact.

[0021] The polyethylene cooling fabric of the present invention contains titanium dioxide, providing a luxurious feel and a UV-blocking effect.

[0022] The polyethylene cooling fabric of the present invention, despite containing titanium dioxide, prevents an increase in pack pressure and yarn breakage that occur during the yarn spinning process, thereby having equivalent physical properties to a cooling fabric using only polyethylene.

[0023] 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.

[0024] 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.

[0025] In this specification, 'radiant yarn' means yarn radiated through a radiant chamber, also called radiant yarn, and means yarn before cooling treatment.

[0026] In this specification, 'unstretched yarn' means yarn that has been cooled and drawn before being subjected to stretching.

[0027] In this specification, 'drawn yarn' means a yarn that has been drawn.

[0028] The present invention is described in detail below.

[0029] 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.

[0030] 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.

[0031] While high contact cooling performance can be achieved with high-density polyethylene alone, adding additional ingredients to create functional fabrics can reduce cooling performance or impact the spinning process, degrading the yarn's physical properties. In particular, the addition of inorganic additives can cause agglomeration during the melting and spinning processes, leading to increased pack pressure and yarn breakage during the spinning stage, significantly reducing production processability.

[0032] The polyethylene cooling fabric of the present invention contains titanium dioxide and has a Qmax value of 0.3 W / cm 2 It maintains a high cooling function and has mechanical properties (strength and elongation, etc.) equivalent to those of yarns that do not use titanium dioxide.

[0033] Titanium dioxide (TiO2) is a chemically stable substance with a matte finish, low relative density, high dielectric constant, semiconductor properties, excellent thermal stability, hydrophilicity, high hygroscopicity, and UV protection. These properties make it useful in a wide range of applications, including photocatalytic coating materials, gloss control in paints, inks, plastics, paper, and fibers like rubber, as well as in food and cosmetics (as UV blockers), pharmaceutical additives, matting agents, water purification and wastewater treatment, deodorization and sterilization (as an eco-friendly paint additive), and solar cells.

[0034] In the present invention, the addition of titanium dioxide reduces the gloss of the fabric itself, giving it a luxurious feel, and imparts a new functionality of UV blocking, enabling the fabric to be manufactured as a functional fabric.

[0035] The polyethylene cooling fabric of the present invention has a UV blocking rate of 95% or more, 97% or more, 98% or more, and 99% or more, and a UV blocking index of 30 or more, 40 or more, and 50 or more, as measured according to KS K ISO 139. Such a high UV blocking effect can eliminate a separate UV coating process after the fabric is commercialized. In addition, in the case of a method of separately coating for UV blocking, the effect decreases over time due to the coating layer being peeled off by environmental factors such as rain, snow, washing, and contamination, whereas the polyethylene cooling fabric of the present invention continuously maintains the UV blocking effect due to the presence of titanium dioxide in the yarn itself.

[0036] The polyethylene cooling fabric of the present invention has a density of 70 to 1300 g / m 2It 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 the existence of many voids within the fabric, which reduces the coolness of the fabric. On the other hand, 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.

[0037] The addition of titanium dioxide can coat the surface of a cooling fabric made of polyethylene yarn, but in this case, it is not easy to uniformly coat titanium dioxide, and an additional process for coating is required, which increases the cost.

[0038] Accordingly, in the present invention, polyethylene yarn is used as a raw material, and titanium dioxide is mixed with polyethylene resin prior to the spinning process to manufacture the yarn. As a result, titanium dioxide can be easily added to polyethylene yarn without additional processes, and the titanium dioxide is uniformly present throughout the fabric, thereby ensuring the effects of using the titanium dioxide. However, since titanium dioxide is an inorganic substance, and as mentioned above, it can cause deterioration of physical properties due to increased pack pressure and yarn breakage during the spinning process, control of the titanium dioxide used is necessary.

[0039] Below, we will take a closer look at the manufacturing method of polyethylene yarn.

[0040] The polyethylene yarn of the present invention is manufactured by including the steps of mixing and melting polyethylene resin and titanium dioxide; spinning through a spinneret and then cooling; and multi-stage drawing and winding the obtained undrawn yarn using equipment equipped with multi-stage drawing godet rollers.

[0041] Each step is explained below.

[0042] First, polyethylene resin and titanium dioxide are mixed and melted as raw materials to manufacture polyethylene yarn.

[0043] 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 / 1 0 min and a melt index (MI) (at 190°C) of 2 to 20 g / 1 0 min. Considering that the polydispersity index may decrease during the spinning process, the polyethylene of the present invention 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).

[0044] 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-feeling raw fabrics that are intended for contact with the user's skin.

[0045] 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.

[0046] 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, reducing 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.

[0047] In the present invention, titanium dioxide having an adjusted average particle size is used.

[0048] The average particle size is measured using a Shimadzu Model SALD-2300 analyzer with a Flow Cell type. The 'average particle size' refers to the average particle size of the entire sample, 'D10' refers to the particle size corresponding to 10 wt% of the cumulative percentage distribution, 'D50' refers to the particle size corresponding to 50 wt% of the cumulative percentage distribution, and 'D90' refers to the particle size corresponding to 90 wt% of the cumulative percentage distribution.

[0049] The titanium dioxide used in the present invention has an average particle size of 0.2 µm to 0.5 µm, a D10 of 0.1 µm to 0.2 µm, a D50 of 0.2 µm to 0.3 µm, and a D90 of 0.3 µm to 0.5 µm, and a narrow particle size distribution is used.

[0050] To manufacture yarn, polyethylene in chip form is fed into an extruder, and titanium dioxide is fed into the extruder in an amount of less than 0.7 wt%, less than 0.6 wt%, less than 0.5 wt%, more than 0.1 wt%, more than 0.15 wt%, or more than 0.2 wt% based on the total weight of the polyethylene, and then melted. The content of the titanium dioxide is within a range that can secure the gloss and UV-blocking effect of the fabric without reducing the cooling function, and suppress an increase in pack pressure and yarn breakage in the yarn manufacturing process.

[0051] Next, the molten mixture is radiated through a spinneret and then cooled.

[0052] Specifically, the molten mixture is conveyed through a spinneret by a screw and extruded through a plurality of holes formed in the spinneret.

[0053] 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.

[0054] 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, for example, it is preferable to perform the process at 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.

[0055] It is preferable to use a 100-mesh to 500-mesh spinning filter (a filter mesh made of metal wire) during spinning. This is to remove foreign substances and impurities remaining in the polyethylene chips or titanium dioxide raw material, and to uniformly form a pressure on the chips remaining in the pack to ensure uniform fineness between the yarns.

[0056] In the spinning process using a radiation filter, titanium dioxide coagulates, increasing the pack pressure. This increased pack pressure causes yarn breakage, which breaks the unstretched yarn. This breakage reduces yarn quality and ultimately reduces productivity.

[0057] In particular, limiting the content of titanium dioxide is very important because the addition of excessive amounts of titanium dioxide increases the pack pressure.

[0058] The increase in pack pressure can be measured by the pack pressure increase rate parameter.

[0059] The rate of increase in pack pressure is calculated by measuring the pressure of the radiation filter over time during the radiation process based on 24-hour operation, and using the following equation (1).

[0060] [Formula 1]

[0061] Pack pressure increase rate (%) = [(P2- P1) ÷ P1] × 100

[0062] (In the above formula, P1 means the initial pack pressure at the start of radiation, and P2 means the pack pressure 24 hours later.)

[0063] Based on the above formula, the pack pressure increase rate in the radiation process of the present invention is 20% or less, 17% or less, 14% or less, 10% or less, 8% or less, and 5% or less. Excessive use of titanium dioxide further increases the pack pressure increase rate, ultimately resulting in a decrease in productivity.

[0064] The emitter passes through a cooling zone to obtain cooled emitter, i.e., unstretched emitter.

[0065] Cooling may be performed by, 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 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, which may increase the fineness difference between undrawn yarns, which may cause yarn breakage during the drawing process.

[0066] If necessary, an additional step of applying an oil to the unstretched yarn obtained after cooling using an oil roller (OR) or an oil jet may be included. The oil application step may be performed using the Metered Oiling (MO) method, and applies an oil that reduces the friction coefficient in a short period of time while also exhibiting excellent stretchability and thermal efficiency.

[0067] Next, the polyethylene yarn is manufactured through a step of multi-stage stretching and winding using equipment equipped with multi-stage stretching godet rollers.

[0068] Multi-stage stretching is performed by multi-stage stretching including multiple godet rollers (GR1...GRn) and is performed by controlling the total stretching ratio.

[0069] The total draw ratio applied during the drawing process is adjusted to 2.5 to 7.5, preferably 3.5 to 7.5. A low draw ratio reduces the crystallinity of the polyethylene yarn, resulting in a decrease in the Qmax value. Conversely, an excessively high draw ratio reduces properties such as strength, tensile modulus, and elongation, resulting in poor weaving properties and a stiff feel.

[0070] In the plurality of godet rollers (GR1...GRn) for multi-stage drawing, the temperature of the first godet roller (GR1) may be 40 to 80°C, and the temperature of the last godet roller (GR5, or GRn) may be 110 to 140°C. The temperature of each of the remaining godet rollers excluding the first and last godet rollers may be set to be the same as or higher than the temperature of the preceding godet roller. The temperature of the last godet roller may be set to be the same as or higher than the temperature of the preceding godet roller, but may be set slightly lower due to warping. For example, an undrawn yarn may be passed through five-stage drawing godet rollers (GR1, GR2, GR3, GR4, GR5) to be multi-stage thermally drawn and wound.

[0071] Meanwhile, when titanium dioxide coagulates with each other during the radiation process, the pack pressure increases and the unevenness of the undrawn yarn increases, resulting in a decrease in physical properties such as strength, which in turn causes yarn breakage in which the undrawn yarn is cut during the multi-stage drawing stage for drawing.

[0072] The number of spin-offs is defined as the number of times a yarn is cut during its movement from the spinneret to the first godet roller in 24 hours of operation. The cut yarn may be a spun yarn, an undrawn yarn, or both. The number of spun-offs of the spun yarn or the undrawn yarn according to the present invention occurs 1 or less, preferably 0, and this can be achieved by limiting the content of titanium dioxide. Excessive use of titanium dioxide increases the number of spun-offs, ultimately resulting in a decrease in productivity.

[0073] The above multi-stage drawn yarn is subjected to multi-stage drawing and heat setting simultaneously and is wound on a winder to produce the polyethylene yarn of the present invention.

[0074] 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 .

[0075] 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, 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.

[0076] 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.

[0077] 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 becomes insufficient and the contact area with the body becomes small, so that it cannot provide sufficient cooling sensation to the user. In general, the DPF can be adjusted through the output amount and draw ratio in the spinneret.

[0078] 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.

[0079] The polyethylene yarn of the present invention can provide a sense of luxury by lowering the gloss compared to a polyethylene yarn alone that does not contain titanium dioxide.

[0080] The luxurious color of the yarn can be measured using a colorimeter to measure color fastness.

[0081] A colorimeter (a color measuring instrument) detects differences that are not visible to the naked eye and then immediately displays these differences numerically, using the L*a*b* values ​​to identify color differences. The L*a*b* color space defined by the CIE is modeled after the color selection theory that two colors cannot be red and green at the same time, or yellow and blue at the same time, where L* represents brightness, a* is the red / green coordinate, and b* is the yellow / blue coordinate. The deltas for L* (ΔL*), a* (Δa*), and b* (Δb*) can be positive or negative.

[0082] As titanium dioxide is added compared to polyethylene yarn alone, the L* value increases to a positive value, and a* and b* increase to negative values. The values ​​of L*, a*, and b* change depending on the content of titanium dioxide, and as the content increases, a* and b* increase to more negative values, but the L* value is hardly affected.

[0083] The color fastness of the polyethylene yarn of the present invention is such that the L* value is 92 to 97, 95 to 97, and 96 to 97, the a* value is a negative value less than 0, -1 to less than 0, -0.7 to less than 0, -0.5 to less than 0, -0.3 to less than 0, and -0.2 to less than 0, and the b* value is a negative value less than 0, -1 to less than 0, -0.9 to less than 0, -0.7 to less than 0, -0.5 to less than 0, and -0.3 to less than 0. The meaning of the above numbers is that, compared to a polyethylene yarn alone, the brightness increases as titanium dioxide is added, and it is closer to green than red and closer to blue than yellow, and these values ​​are values ​​that can feel a sense of luxury when judged with the naked eye compared to a polyethylene yarn alone.

[0084] Specifically, after winding 10,000 m of 400d (denier) yarn on a bobbin, CCM (Computer Color Matching) measurement of the surface of the wound yarn is performed, and after measuring a total of 10 times to obtain an average value, the color difference (dE) value can be calculated according to the following equation (2).

[0085] [Formula 2]

[0086] dE = [(L1-L0) 2 + (a1-a0) 2 + (b1-b0) 2 ] 1 / 2

[0087] (In the above formula, L1, a1, b1 are L*, a*, b* of the polyethylene yarn containing titanium dioxide. The values ​​are L0, a0, b0, and L*, a*, and b* of the yarn of polyethylene yarn without titanium dioxide. It's worth it.)

[0088] The polyethylene yarn of the present invention has a dE value of less than 7, 6.5 or less, 6.2 or less, and 4.0 or more, 4.5 or more, or 5.0 or more.

[0089] Made from the aforementioned polyethylene yarn, the polyethylene cool-touch fabric is comfortable and cool because it doesn't feel sticky due to sweat or moisture. It also absorbs sweat and moisture well and dries quickly. Furthermore, it doesn't cling to the body, maintaining a soft feel. It also wicks away body heat, leaving the skin feeling cool and cool to the touch. Furthermore, it blocks UV rays, protecting the skin from UV rays, making it extremely useful for extended outdoor activities.

[0090] 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.

[0091] Hereinafter, an embodiment according to the present invention will be described.

[0092] [Measurement of physical properties]

[0093] - Color fastness: The surface of 400d (denier) yarn wound 10,000 m on a bobbin was measured using a colorimeter.

[0094] - Color difference (dE) value: After winding 10,000 m of 400d (denier) yarn, CCM (Computer Color Matching) measurement of the surface of the wound yarn was performed. A total of 10 measurements were taken to obtain an average value, and the color difference (dE) value was calculated using the following equation (2).

[0095] [Formula 2]

[0096] dE = [(L1-L0) 2 + (a1-a0) 2 + (b1-b0) 2 ] 1 / 2

[0097] (In the above formula, L1, a1, and b1 are values ​​of polyethylene yarn containing titanium dioxide, and L0, a0, and b0 are values ​​of polyethylene yarn alone not containing titanium dioxide (Comparative Example 1).)

[0098] - 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.

[0099] - 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.

[0100] *Light source (X-ray source): Cu-Kα radiation

[0101] *Power: 45 KV x 25mA

[0102] *Mode: Continuous scan mode

[0103] *Scan angle range: 10~40°

[0104] *Scan speed: 0.1° / sec

[0105] - Pack pressure increase rate: The pressure of the radiation filter during the radiation process was measured over time based on 24-hour operation, and calculated using the following equation (1).

[0106] [Formula 1]

[0107] Pack pressure increase rate (%) = [(P2- P1) ÷ P1] Х 100

[0108] (In the above formula, P1 means the initial pack pressure at the start of radiation, and P2 means the pack pressure 24 hours later.)

[0109] - Number of thread breaks: The number of times the thread is cut while moving from the spinneret to the first roller is measured based on 24-hour operation.

[0110] - 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.

[0111] - UV blocking rate: Measured using a UV-VISIBLE-NIR Spectrophotometer according to KS K ISO 139. The UV transmittance of the sample was measured by scanning a wavelength of 290-400 nm at least every 5 nm using a Xenon Arc light source. The UV blocking rate was calculated as 100-UV transmittance.

[0112] - UV protection index: Measured according to KS K ISO 139, and the results were calculated according to the following equation (3).

[0113] [Formula 3]

[0114]

[0115] S λ : Erythema coefficient at each wavelength

[0116] E λ : Solar energy by wavelength at 35 degrees north latitude

[0117] T λ : Spectral transmittance (%)

[0118] Δλ: Measurement wavelength interval

[0119] λ: wavelength

[0120] [Yarn manufacturing]

[0121] Polyethylene resin (80,000 g / mol) and titanium dioxide were fed into an extruder with the contents shown in Table 1 below. At this time, titanium dioxide with an average particle size of 0.2 ㎛ to 0.5 ㎛, D10 of 0.1 ㎛ to 0.2 ㎛, D50 of 0.2 ㎛ to 0.3 ㎛, and D90 of 0.3 ㎛ to 0.5 ㎛, and a narrow particle size distribution was used.

[0122] Next, the yarn was extruded through a spinneret at a spinning temperature of 260℃, and the produced yarn was moved to a cooling zone to be cooled. Next, the undrawn yarn was drawn in two stages to an overall draw ratio (DR) of 5.4, and wound at a winding speed of 2100 m / min to produce polyethylene yarn with a total fineness of 400d (denier). The properties of the yarn were then measured and are shown in the table below.

[0123] [Fabric Manufacturing]

[0124] The manufactured yarn was woven to produce a cool-feeling fabric with a density of 500 g / m2. The physical properties of the manufactured cool-feeling fabric were measured and are shown in the table below.

[0125] [result]

[0126] Classification Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Titanium dioxide content (wt%) 0.2 0.5 0.7 0 1.0 1.2 Yarn color intensity L*969796919898a*-0.1-0.2-0.10.2-0.2-0.2b*-0.2-0.3-0.3-0.2-0.4-0.3dE5.0 16.0 15.01-7.0 17.01 Strength (g / d) 4.9 5.15.0 5.0 5.25.4 Elongation (%) 25 24 25 24 24 23 Crystallinity (%) 76.1 76.5 75.9 77.275.6 75.5 Packing pressure Increase rate (%) 4.38.5173.222.327.7 Number of radiation rejections (times) 001013 Fabric Qmax (W / cm) 2 )0.3120.3030.3010.3140.2900.273UV protection rate (%)99.199.399.487.399.699.7UV protection factor505055205555

[0127] As shown in the table above, the cool fabrics of the examples and comparative examples to which titanium dioxide was added showed a tendency for the Qmax value to decrease compared to Comparative Example 1. Among them, when the content of titanium dioxide added was adjusted as in Examples 1 to 3, the Qmax value was 0.3 W / cm, which is equivalent to the cool fabric of Comparative Example 1. 2The above Qmax value could be maintained. In addition, due to the addition of titanium dioxide, the cool fabrics of Examples 1 to 3 secured a UV blocking effect compared to the cool fabric of Comparative Example 1. In addition, as the content of titanium dioxide increased, the color fastness of the yarn changed, and the color difference (dE) value of the yarns of Examples 1 to 3 showed about 5 to 6, and it can be seen that among them, it affected the value of brightness (L*).

[0128] The content of titanium dioxide also had a slight effect on the strength, elongation, and crystallinity of the yarn. Specifically, the yarns of Examples 1 to 3 had comparable properties to the yarn of Comparative Example 1, which did not use titanium dioxide. In contrast, the yarn of Comparative Example 3 showed increased strength but decreased elongation.

[0129] In particular, the content of titanium dioxide significantly affects the rate of increase in pack pressure and the number of radiation rejections.

[0130] Compared to the yarn of Comparative Example 1, the addition of titanium dioxide resulted in an increase in pack pressure and an increase in the number of spinning breaks. In particular, the yarn of Comparative Example 3 showed a pack pressure increase rate of up to 9 times or more, and the number of spinning breaks also increased by more than 3 times. In comparison, for the yarns of Examples 1 to 3, it was possible to minimize the increase in pack pressure and significantly reduce spinning breaks by adjusting the content of titanium dioxide.

Claims

1. A polyethylene cooling fabric manufactured from polyethylene yarn. The above polyethylene yarn contains 0.2 to 0.7 wt% of titanium dioxide based on its total weight, The above polyethylene cooling fabric has a contact cooling (Qmax, average value after 5 measurements) value of 0.3 W / cm, measured by contacting a 40±2℃ hot plate (T-box) to a 20±2℃ fabric at 20±2℃ and 65±4% relative humidity. 2 Ideal, polyethylene cooling fabric.

2. In paragraph 1, The above polyethylene yarn is wound on a bobbin with 400d (denier) yarn of 10,000 m, and CCM (Computer Color Matching) measurement is performed 10 times in total on the surface of the wound yarn to obtain an average value, and then the color difference (dE) value calculated according to the following formula (2) is less than 7, a polyethylene cool-touch fabric: [Formula 2] dE = [(L1-L0) 2 + (a1-a0) 2 + (b1-b0) 2 ] 1 / 2 (In the above formula, L1, a1, b1 are L*, a*, b* of polyethylene yarn containing titanium dioxide. The values ​​are L0, a0, b0, and L*, a*, and b* of the yarn of polyethylene yarn without titanium dioxide. It's worth it.) 3. In paragraph 1, The above polyethylene yarn is a polyethylene cool-touch fabric having an L* value of 92 to 97, an a* value of a negative value less than 0, and a b value of a negative value less than 0.

4. In paragraph 1, The above polyethylene yarn is a polyethylene cool-touch fabric having a strength of 4 g / d or more when measured at a length of 250 mm, an ambient temperature of 20±2℃, and a relative humidity of 65±4% according to ASTM D2256.

5. In paragraph 1, The above polyethylene yarn is a polyethylene cool-touch fabric having an elongation of 25% or less when measured at a length of 250 mm, an ambient temperature of 20±2℃, and a relative humidity of 65±4% according to ASTM D2256.

6. In paragraph 1, A polyethylene cool-touch fabric, 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.

7. In paragraph 1, The above polyethylene yarn is a polyethylene cool-feel fabric having a crystallinity of 60% to 85%.

8. In paragraph 1, The above polyethylene yarn is a polyethylene cool-feel fabric manufactured by melting and spinning polyethylene resin and titanium dioxide and then stretching them.

9. In paragraph 8, The above polyethylene is a polyethylene cooling fabric having a weight average molecular weight (MW) of 50,000 to 99,000 g / mol.

10. In paragraph 8, The above polyethylene yarn is a polyethylene cool fabric having a pack pressure increase rate of 20% or less, calculated by the following formula (1) after measuring the pressure of the spinning filter applied during the spinning process over time based on 24-hour operation during the spinning: [Formula 1] Pack pressure increase rate (%) = [(P2- P1) χ P1] × 100 (In the above formula, P1 means the initial pack pressure at the start of radiation, and P2 means the pack pressure 24 hours later.) 11. In paragraph 1, Polyethylene cool-touch fabric with a UV blocking rate of 95% or higher and a UV blocking index of 30 or higher, measured according to KS K ISO 139.

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