KR20220092605A - Radiant cooling fabric and method of making the same - Google Patents

Abstract

The fabric includes one or more yarns. Each of the one or more yarns includes a plurality of filaments. Each of the filaments has an average diameter in the range of 20-50 μm, whereby the fabric has an IR transmission of at least 37% at a wavelength of 9.5 μm.

Description

Radiant cooling fabric and method of making the same

Cross-referencing of related applications

This application is filed on November 6, 2019, and is filed under U.S. Provisional Application No. 35 U.S.C. of 62/931,727. 119(e), the content of which is incorporated herein in its entirety.

technical field

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates generally to fabrics for garments, and more particularly to radiative cooling fabrics for garments and methods of making the same.

Issues related to the energy crisis and climate change are becoming more important and need to be addressed. According to a recent study, 15% of the total electricity consumed worldwide is used to cool homes and offices, which causes an increase in greenhouse gas emissions worldwide. Accordingly, there is a need to develop a new technology capable of reducing energy demand. For example, increasing the cooling setpoint by 2°C can save energy by more than 20% worldwide.

Personal cooling management will be an effective way to reduce energy costs. In a typical indoor environment, when the skin temperature of the human body is 33.5℃, the body's radiant heat loss in mid-infrared thermal radiation (wavelength range of 7-14μm) accounts for more than 50% of the total heat loss. Most conventional textile fabrics, such as cotton and polyester, fail because they are infrared (IR) opaque materials.

Radiant cooling fabrics and garments made from the fabrics, and methods of making the fabrics, are described herein.

In one aspect, the fabric comprises one or more yarns. Each of the one or more yarns includes a plurality of filaments. Each of the filaments has an average diameter in the range of 20-50 μm, whereby the fabric has an IR transmission of at least 37% at a wavelength of 9.5 μm. In some embodiments, the fabric has a stiffness of less than 50 as measured by a PhabrOmeter or Nu Cybertek system.

In some embodiments, each of the one or more yarns has an average diameter of at most 400 μm. In some embodiments, the one or more yarns include at least one yarn having a coating on its surface. One or more yarns may have a different color by including a dye. In some embodiments, the one or more yarns include sunscreen. In some embodiments, the sunscreen comprises ZnO or TiO ₂ . In some embodiments, the one or more yarns include one or more ceramic fillers.

In some embodiments, the fabric has a porosity in the range of 0-12%. Porosity is defined herein as 1 - the cover factor.

In some embodiments, the filaments comprise one or more of polyethylene, polypropylene, or polyamide.

In another aspect, the device comprises a fabric. The fabric includes one or more yarns. Each of the one or more yarns includes a plurality of filaments. Each of the filaments has an average diameter in the range of 20-50 μm, whereby the fabric has an IR transmission of at least 37% at a wavelength of 9.5 μm. In some embodiments, the device comprises one of a garment, a shoe, a tent, or a sleeping bag.

Certain features of various embodiments of the present technology are specifically set forth in the appended claims. A better understanding of the features and advantages of the present technology will be obtained by reference to the following detailed description, which presents exemplary embodiments in which the principles of the present invention are employed, and the accompanying drawings.
1 is a schematic diagram depicting a yarn production apparatus according to an exemplary embodiment.
2 is a diagram showing the cooling performance, fabric thickness, and IR transmittance of various woven fabrics.
3 is a diagram illustrating stiffness test data and thickness data of a PE fabric formed by the disclosed technique, in accordance with an exemplary embodiment.
4 is a diagram illustrating stiffness test data and thickness data of a conventional PET fabric.

In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments of the invention. However, it will be understood by one of ordinary skill in the art that the present invention may be practiced without these details. In addition, while various embodiments of the present invention are disclosed herein, many modifications and variations can be made within the scope of the present invention in accordance with the common general knowledge of those skilled in the art. Such modifications include substitutions of known equivalents for any aspect of the invention for achieving the same result in substantially the same manner.

Unless the context requires otherwise, the terms "comprises" and variations thereof, such as "comprises(s)" and "comprising" throughout this specification and claims, are in an open and inclusive sense, i.e., "including but not limited to". should be construed as "not". Recitation of a numerical range of values throughout this specification is a shorthand notation of individually reciting each individual value falling within the inclusive range of values defining that range, and each individual value is incorporated herein as if it were individually recited. do. Additionally, the singular forms "a" and "the" include plural objects unless the context clearly dictates otherwise.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification may, but are not necessarily all referring to the same embodiment. Moreover, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Various embodiments described herein relate to IR transmissive fabrics for personal body cooling purposes. Previous studies in this field have suggested that fabrics made of fibers/filaments with a diameter of about 1 μm or less are effective for infrared transmission. It has been found that the fibers must be made with a small diameter (eg, a few micrometers or narrower) to be able to pass infrared light from the human body. However, small diameter fibers are weak in ordinary textile manufacturing processes. The techniques disclosed herein use fibers with much larger diameters of at least 20 μm to produce stronger yarns for radiant cooling fabrics, which significantly improves manufacturing quality and speed as traditional textile materials. The techniques disclosed herein also provide fabrics that are infrared transmissive. For example, the disclosed fabric has an IR transmittance of at least 37% at a wavelength of 9.5 μm.

An embodiment will now be described in conjunction with the accompanying drawings. First refer to FIG. 1 . 1 is a schematic diagram depicting a yarn production apparatus 100 according to an exemplary embodiment. The yarn making apparatus 100 includes a food hopper 102 configured to receive polymer granules 104 . The polymer granules 104 include one or more materials selected to form thin filaments for the yarn. For example, this material may include selected polymers and other additives. In some embodiments, the selected polymer may comprise one or more of polyethylene, polypropylene, or polyamide. In some embodiments, selected additives may include colorants, ultraviolet (UV) protection agents, or other functional agents.

The yarn making apparatus 100 further includes a heating unit 106 that melts the polymer granules 104 at a predetermined elevated temperature to produce a polymer melt 108 . The polymer used to make the polymer yarn may comprise, for example, linear low density PE (LLDPE) or high density PE (HDPE) having a viscosity in the range of 17-30 g/10 min (as per ASTM D1238), which is then melted Provides moderate mobility during extrusion. A pump 110 is used to move the polymer melt 108 to a spin nozzle device 112 comprising a plurality of spin nozzles 112-1. Each of the spinning nozzles 112-1 extrudes/produces filaments/fibers 114 that are collected by the yarn driving rollers 116 . Depending on the number of spinnerets 112-1 of the spinneret device and the material flow rate, different filament sizes with varying filament counts can be obtained. In some embodiments, the average diameter of the filaments 114 is controlled to be in the range of 20-50 μm. In some embodiments, to form a cooling fabric with good skin feel, the average diameter of the filaments 114 is 25-50 μm, 30-50 μm, 35-50 μm, 40-50 μm, 20-45 μm, 25-45 μm, 30 Controlled in the range of -45μm, 35-45μm, 20-40μm, 25-40μm, 30-40μm, 20-35μm, 25-35μm, or 20-30μm.

As the filament 114 is pulled by the yarn driving roller 116 , the filament 114 is cooled by the air 118 . In some embodiments, alternatively or additionally, after the filaments 114 have cooled, they may be steamed 120 to modify their properties. In some embodiments, the as-spun multifilament yarn is drawn from the spin nozzle 112-1 at a draw ratio of at least 2.2:1 and twisted at at least 155/m to form a strong yarn. The stretching process increases the mechanical strength, such as tenacity and elongation, of the polymer yarn 122 . For example, a drawn PE yarn can have a toughness of at least 1.61 g/d and an elongation of up to 111.26%. Filament 114 is collected by yarn driving roller 116 to form yarn 122 , which is fed to feed roller 124 . The yarn 122 is then rolled onto a bobbin 126 and ready to make a fabric.

One or more yarns 122 are made into a fabric for personal cooling garments by weaving and knitting techniques. In some embodiments, reducing the fabric thickness and controlling the fiber/filament and yarn size can have a significant effect on the cooling performance of the garment as both fiber and yarn size affect IR transmittance. In particular, it has been found that the fiber size of the yarn must have a diameter of about 1 μm to be effective for acceptable IR transmission. However, using the techniques disclosed herein, the fiber size of the yarn 122 is controlled within the range of 20-50 μm, which is about 20-50 times greater than the fiber size in prior art studies on cooling garments. The disclosed technique involves the selection of a polymeric material, fiber size, and yarn size to form a fabric that is strong and IR transmissive. For example, the one or more polyethylene, polypropylene, or polyamide is 20-50 μm, 25-50 μm, 30-50 μm, 35-50 μm, 40-50 μm, 20-45 μm, 25-45 μm, 30-45 μm, 35-45 μm. , 20-40 μm, 25-40 μm, 30-40 μm, 20-35 μm, 25-35 μm, or 20-30 μm for fibers with diameters that can achieve acceptable IR transmission.

To be effective for IR transmission, the diameter of the yarn 122 is controlled to be up to 400 μm. In some embodiments, the diameter of the yarn 122 is at most 350 μm, 300 μm, 250 μm, or 200 μm. In some embodiments, the diameter of the yarn 122 is 200-400 μm, 200-350 μm, 200-300 μm, 200-250 μm, 250-400 μm, 250-350 μm, 250-300 μm, 300-400 μm, 300-350 μm, or 350 μm. It is in the range of -400 μm.

This finding allows the fabric to have an IR transmittance of at least 37% at a wavelength of 9.5 μm. In some embodiments, fabrics formed by the techniques disclosed herein can have an IR transmittance of at least 38%, 40%, 42%, 45%, or 50% at a wavelength of 9.5 μm. In some embodiments, the fabric formed by the techniques disclosed herein is 37-50%, 37-45%, 37-40%, 38-50%, 38-45%, 40-50%, 40 at a wavelength of 9.5 μm. It may have an IR transmittance in the range of -45%, or 45-50%.

In some embodiments, the weaving and knitting processes to form the fabric may introduce voids in the fabric structure. For example, the fabric may have a porosity in the range of 0-12%. The voids can be used to modify the properties of the fabric, including IR transmittance and breathability.

In some embodiments, the yarn can be formed with various colorants that can provide color to the yarn to create a pattern or color in the fabric. In some embodiments, the yarn may be formed with other functional agents. For example, one or more UV blocking agents may be added to the yarn to provide the yarn with the ability to provide better UV-blocking function. In some embodiments, the UV blocking agent may include ZnO and TiO ₂ . In some embodiments, the functional agent may be added to the yarn in the form of a ceramic filler. In some embodiments, the added functional agent is added to the point where the maximum fabric IR transmittance (at a wavelength of 9.5 μm) drop does not exceed more than 15%.

2 is a diagram showing the cooling performance, fabric thickness, and IR transmittance of various fabrics. First, Figure 2 shows the cooling performance of two woven PE fabric samples formed by the techniques disclosed herein compared to traditional polyester and cotton woven fabric samples. The results show that PE fabric with a thickness of 0.28 mm (150D (denier)/24F (number of filaments per yarn), yarn diameter 285 μm, filament diameter 37 μm) was compared with conventional PET woven fabric (0.29 mm thickness) and cotton broadcloth at skin temperature. 2.1°C and 1.9°C cooler than the fabric (0.27 mm thick), respectively; On the other hand, PE fabric with a thickness of 0.36 mm (150D/50F yarn diameter 285 μm, filament diameter 22 μm) was 1.8° C. and 1.6° C cooler than PET woven fabric and cotton broadcloth fabric, respectively, at skin temperature. In addition, the IR transmittance is 50%, 37%, 0%, and 0% for 150D/24F PE fabric, 150D/50F PE fabric, PET woven fabric, and cotton broadcloth fabric, respectively. These results demonstrate the advantages of the disclosed PE fabrics in thermal control.

In some embodiments, fabrics formed by the techniques disclosed herein may have a stiffness of less than 50. 3 is a diagram illustrating stiffness testing and thickness data of a PE fabric formed by the disclosed technique, in accordance with an exemplary embodiment. 4 is a diagram illustrating stiffness test and thickness data of a conventional PET fabric. The stiffness test is performed based on the American Association of Textile Chemists and Colorists (AATCC) TM202 standard.

As shown in Figure 3, a woven fabric made of 150D/24F PE yarns (yarn diameter 285 μm; filament diameter 37 μm) with a thickness of 0.26 mm has a stiffness of 42.55 and 500D/72F PE yarns with a thickness of 0.53 mm (yarn size 376 μm). ; woven fabric made of filament diameter 37 μm) has a stiffness of 49. Woven fabrics made of 150D/24F PE yarns have a softer feel than woven fabrics made of 500D/72F PE yarns. These results represent the additional benefit of controlling yarn diameters up to 400 μm in apparel applications, with smaller yarn sizes resulting in thinner fabrics with better drape.

As shown in Figure 4, woven PET fabric sample 1 (thickness 0.38 mm) with a filament diameter of 36 μm had a stiffness of 56.64, and woven PET fabric sample 2 (thickness of 0.41 mm) with a filament diameter of 15 μm had a stiffness of 44.24. In conventional fabrics the filament diameter should be less than 20 μm to obtain an acceptable skin feel (stiffness less than 50). Referring again to FIG. 3 , fabrics made by the techniques disclosed herein can achieve acceptable stiffness even when the filament diameter is 37 μm.

In summary, fabrics consistent with the present invention achieve good infrared transmittance, good cooling performance and good drape, making them suitable for apparel applications. The fabric can also be used in other applications requiring cooling fabrics.

In one aspect, the disclosed radiation cooling fabric has an IR transmittance of at least 37% at a wavelength of 9.5 μm, for example from transmittance data collected from a thermal camera.

In another aspect, the fabric may be made from a material having an infrared transmittance of at least 38% at a wavelength of 9.5 μm. Materials can include, but are not limited to, polyethylene, polypropylene, and polyamide.

In another embodiment, the fabric is made from yarns of filaments having an average diameter in the range of 20-50 μm. The yarns have an average diameter of up to 400 μm.

In another embodiment, the radiation cooled fabric made with the drawn PE yarn has a thickness of up to 400 μm and a porosity range of 0-12%.

In another aspect, the yarn may be coated with a sizing material prior to weaving or knitting to avoid static, increase strength, and improve bonding of the filaments.

The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. The breadth and scope of the present invention should not be limited by any of the foregoing exemplary embodiments. Many modifications and variations will be apparent to those skilled in the art. Modifications and variations include related combinations of the disclosed features. The embodiments have been chosen and described which best explain the principles of the invention and its practical application, so that those skilled in the art can understand the invention in accordance with various embodiments, and can consider various modifications as are suited to the particular use. It is intended that the scope of the present invention be defined by the following claims and their equivalents.

Claims (20)

A fabric comprising one or more yarns, each of the one or more yarns comprising a plurality of filaments, each of the filaments having an average diameter in the range of 20-50 μm, such that the fabric has at least 37% infrared radiation at a wavelength of 9.5 μm. (IR) Fabric with transmittance. A fabric according to claim 1, characterized in that the filaments have an average diameter in the range of 20-40 μm. The fabric of claim 1 wherein the filaments comprise at least one of polyethylene, polypropylene, or polyamide. The fabric of claim 1 wherein the fabric has a porosity in the range of 0-12%. The fabric of claim 1 , wherein the at least one yarn comprises at least one yarn having a coating on its surface. 2. The fabric of claim 1, wherein at least one of the yarns contains a dye. 2. The fabric of claim 1, wherein at least one of the yarns comprises a sunscreen. The fabric of claim 7 wherein the sunscreen comprises at least one of ZnO or TiO ₂ . 2. The fabric of claim 1, wherein at least one of the yarns comprises a ceramic filler. The fabric of claim 1 , wherein each of the one or more yarns has an average diameter of at most 400 μm. An apparatus comprising a fabric, wherein the fabric comprises one or more yarns, each of the one or more yarns comprising a plurality of filaments, each of the filaments having an average diameter in the range of 20-50 μm, such that the fabric has an average diameter of 9.5 μm. A device having an infrared (IR) transmittance of at least 37% at a wavelength. The device of claim 11 , wherein the filaments have an average diameter in the range of 20-40 μm. 12. The device of claim 11, wherein the filaments comprise one or more of polyethylene, polypropylene, or polyamide. 12. The device of claim 11, wherein the fabric has a porosity in the range of 0-12%. 12. The apparatus of claim 11, wherein the at least one yarn comprises at least one yarn having a coating on its surface. 12. The apparatus of claim 11, wherein at least one of the yarns contains a dye. 12. The device of claim 11, wherein the at least one yarn comprises a sunscreen. 18. The device of claim 17, wherein the sunscreen comprises at least one of ZnO or TiO ₂ . 12. The apparatus of claim 11, wherein the at least one yarn comprises a ceramic filler. The apparatus of claim 11 , wherein each of the one or more yarns has an average diameter of at most 400 μm.

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