Patent Publication Number: US-11655568-B2

Title: Insulating double-knit fabric

Description:
RELATED APPLICATIONS 
     The present application claims priority to U.S. Provisional Application No. 62/557,950 filed Sep. 13, 2017, entitled “Power Air Insulating Fabric,” and to U.S. Provisional Application No. 62/692,012 filed Jun. 29, 2018, entitled “Power Air Insulating Fabric” the entireties of which applications are hereby incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This invention relates to fabrics, and, more particularly, to insulating performance fabrics, e.g. for wearing apparel, and the like. 
     BACKGROUND 
     Performance fabrics manufactured for use in insulating garments often include fleece fabric, i.e. fabric having a raised or brushed fiber surface for improved insulation performance. The surface of such fabrics is often formed of fleece, which is raised, i.e. given relatively higher loft, by mechanical brushing. It has, however, been recognized that the brushing process can often result in broken fibers, which, over time, can work loose, potentially resulting in microfiber pollution. Loss of fibers, e.g., during washing, can also result in deterioration of insulation performance. Further, it is recognized that broken fibers released during washing can get into wastewater, causing pollution. 
     SUMMARY 
     Improved insulating performance fabrics have a knit, e.g., a double-knit, body, formed with a traditional, relatively smooth, outer surface, and an inner gridded surface with the form of multiple fabric “bubbles” separated by a grid pattern of intersecting grooves. Insulating performance fabrics, including double-knit fabrics of this disclosure, may also be found in the form, e.g., of garments comprising POLARTEC™ Power Air™ performance fabrics, including insulating, double-knit fabrics, e.g., in the form of fabric articles comprising POLARTEC™ Power Air™ fabrics, formed, e.g., of insulating, double-knit fabric, etc. 
     In one aspect of the disclosure, an insulating, double-knit performance fabric includes a first knit layer, a second knit layer coupled with the first knit layer, and a plurality of intermediate fiber regions. The intermediate fiber regions contain a plurality of fibers and positioned between the first knit layer and the second knit layer. The plurality of intermediate fiber regions are positioned in a plurality of air pockets formed by at least one of the first knit layer and the second knit layer. 
     In certain implementations, the insulating, double-knit performance fabric includes one or more of the following additional features. The plurality of intermediate fiber regions may include a plurality of regions of lofted fibers. The lofted fibers may be un-napped, un-brushed and/or are not mechanically lifted. The lofted fibers may be encapsulated in the plurality of air pockets loose. The lofted fibers can extend in a direction having an orthogonal component with respect to the at least one of the first knit layer and the second knit layer. The lofted fibers may be substantially parallel to first knit layer and the second knit layer. The lofted fibers may be randomly positioned. The lofted fibers may include microfibers. The plurality of regions of lofted fibers may be spaced apart from one another. When the plurality of regions of lofted fibers are spaced apart from one another this may be achieved via a plurality of spaced rows separating them. The insulating, double-knit performance fabric element can include at least one braided tube positioned in and extending along at least a portion of at least one space row in the plurality of spaced rows separating the plurality of regions of lofted fibers from one another. The braided tube comprises a monofilament composed, at least in part, of a material that is distinct from the plurality of fibers of the intermediate fiber. The first knit layer and the second knit layer comprise a denier gradient such that the first knit layer has a relatively finer denier than the second knit layer or the second knit layer has a relatively finer denier than the first knit layer. Each of the first knit layer and the second knit layer may have a relatively finer denier than the plurality of intermediate fiber regions. At least one of the first knit layer and the second knit layer may form a smooth surface. At least one of the first knit layer and the second knit layer may define a plurality of windows. The plurality of windows can be positioned over respective spaces of a plurality of spaces separating the intermediate fiber regions from one another. The plurality of intermediate fiber regions may be arranged in a gridded pattern. The plurality of intermediate fiber regions may be arranged in a plurality of rows. In some implementations, each of the intermediate fiber regions include a plurality of rows of fibers extending parallel to the at least one of the first knit layer and the second knit layer. The plurality of fibers of the intermediate fiber regions can include a low melt fiber. The plurality of fibers of the intermediate fiber regions can include at least one of a bi-component filament, a polyester blend, and a polyamide. The bi-component filament can include modacrylic fiber and cellulosic fiber. In some implementations, each of the first knit layer and the second knit layer comprise the air pockets include the plurality of intermediate fiber regions. The first knit layer and the second knit layer may include a circular knit. The first knit layer and the second knit layer can include a double raschel knit. The plurality of intermediate fiber regions can include a plurality of densities of lofted fibers. The intermediate fiber regions in the plurality of intermediate fiber regions that are adjacent a stitch coupling the first knit layer to the second knit layer can have a lower density than intermediate fiber regions in the plurality of intermediate fiber regions that are not adjacent to a stitch coupling the first knit layer to the second knit layer. 
     In another aspect of the disclosure, a garment comprising an insulating, double-knit performance fabric as described according to an implementation disclosed herein is provided. 
     One aspect of the disclosure provides a method of manufacturing an insulating, double-knit performance fabric. The method includes knitting a first layer, knitting a second layer, and positioning and/or attaching a plurality of fibers to at least one of the first layer and the second layer. The plurality of fibers positioned and/or attached as a plurality of separated fiber regions. The method includes encapsulating the plurality of separated fiber regions into a plurality of spaced apart air pockets. The method includes attaching the first layer and the second layer together so as to position the spaced apart air pockets encapsulating the plurality of separated fiber regions between the first layer and the second layer. 
     In certain implementations, the method of manufacturing an insulating, double-knit performance fabric includes one or more of the following processes. The method can include positioning a braided tube in a space between the air pockets encapsulating the plurality of separated fiber regions and between the first layer and the second layer. The method can include exposing the braided tube to heat to fuse a filament forming the braided tube together inside the space. The method can include forming a plurality of windows in at least one of the first layer and the second layer and positioning the plurality of windows over and between the pluralities of air pockets encapsulating the plurality of separated fiber regions. 
     One aspect of the disclosure provides a method of manufacturing an insulating, double-knit performance fabric disclosed herein. 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view of a first (upper) element of a POLARTEC™ Power Air™ fabric of this disclosure. 
         FIG.  2    is a perspective view of a second (lower) element of a POLARTEC™ Power Air™ fabric of this disclosure. 
         FIG.  3    is a perspective view of a POLARTEC™ Power Air™ fabric of this disclosure. 
         FIG.  4    is a perspective view of another embodiment of a POLARTEC™ Power Air™ fabric of this disclosure. 
         FIG.  5    is a plan view of the POLARTEC™ Power Air™ fabric of  FIG.  4   . 
         FIG.  6    is similar plan view of the POLARTEC™ Power Air™ fabric of  FIG.  4   . 
         FIG.  7    is a first side view of the POLARTEC™ Power Air™ fabric of  FIG.  4   . 
         FIG.  8    is a second side view of the POLARTEC™ Power Air™ fabric of  FIG.  4   . 
         FIG.  9    is an example of a yarn of the POLARTEC™ Power Air™ fabric of  FIG.  4     
         FIG.  10    is a somewhat schematic side plan view of the POLARTEC™ Power Air™ fabric of  FIG.  4   . 
         FIGS.  11 A- 11 E  show an embodiment of the POLARTEC™ Power Air™ fabric with windows and an inlay and formed with circular knit. 
         FIGS.  12 A- 12 G  illustrate embodiments of the POLARTEC™ Power Air™ fabric with a solid back and face and formed with double raschel. 
         FIGS.  13 A- 13 D  illustrate an embodiment of the POLARTEC™ Power Air™ fabric with a solid back and an open face and formed with double raschel. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     The invention of the present disclosure, shown, e.g., in  FIGS.  1 - 4   , provides a synthetic material that opens new worlds of design possibilities in this important industry. In particular, over the past half century, the process of developing performance fabrics has continued to evolve and reshape. In this same time span, our knowledge and understanding of how these synthetic materials can potentially have adverse impact on the environment has continued to grow. What&#39;s more, we have also begun to learn more about how, over time, many of these synthetic products continue to break down and shed small particulates, such as microfibers. There is, however, a way to change how synthetic fibers are designed, and thereby to reduce their longer term, undesirable impact. 
     In response, this application introduces POLARTEC™ Power Air™ synthetic fabric material  100  (see, e.g.  FIGS.  1 - 3   ), a revolutionary fabric that reduces microfiber shedding without sacrificing desirable warmth-to-weight ratios. In one particular embodiment, POLARTEC™ Power Air™ synthetic fabric material is a single fabric structure knit into multiple components. For example, referring to  FIGS.  1 - 3   , each of components  100 ,  102  encapsulates air around lofted fibers  118 , thereby to contain body heat in the manner of traditional insulation. The lofted fibers  118  are encapsulated via the knit structure of the fabric material  100 . In particular implementations, the regions of encapsulation are more densely knitted to trap the lofted fibers. The dense knitting is more dense on both the flat side as well as on the bubble side of the encapsulated region, in particular implementations. However, in an exemplary embodiment of the POLARTEC™ Power Air™ synthetic fabric material, these loftier fibers  118  are no longer exposed to outside elements or abrasive surfaces. Rather, these loftier fibers  118  are secured inside each of the air pockets  106 . The result is a fabric  100  that has proven to shed 5× (i.e. five times) less microfibers than standard fleece in laboratory tests. Furthermore, the advantages of the POLARTEC™ Power Air™ fabric design of the present invention do not stop at microfiber retention, as its exposed smooth face  108  reduces friction for less pilling, greater durability and easier layering with other fabrics. 
     In addition, the fabric platform of the POLARTEC™ Power Air™ fabric product creates entirely new categories of performance knits. These performance knits are designed to provide a wearer with relatively more warmth, and less shedding of microfibers, thereby giving any outerwear application of the POLARTEC™ Power Air™ fabric products even wider design versatility, and with a negative impact (i.e. undesirable shedding of microfibers) that has been reduced more than ever before. POLARTEC™ Power Air™ fabric products thus hold “more than just heat”. 
     In one embodiment, the opposite exterior surfaces  110 ,  112  of the POLARTEC™ Power Air™ fabric  100  are smooth and soft, while the respective opposed surfaces  114 ,  116  of the interior construction have the form of a symmetrical grid pattern of air pockets  106 , which are found to provide enhanced encapsulation of fibers and microfibers. In certain embodiments, the grid pattern of air pockets may include spaces between the air pockets  106 . The POLARTEC™ Power Air™ fabric  100  is thus recognized as “holding more than just heat,” and provides a number of particular features and advantages. These include, for example, high warmth-to-weight ratio. They also include shedding of 5 times (i.e., “5.times.”) less microfibers, e.g., as compared to fleece fabrics of similar utility and/or insulation performance. The POLARTEC™ Power Air™ fabric is also versatile in a range of design applications, including with smooth (outer) faces  110 ,  112  for easy layering. The disclosed fabrics, in preferred embodiments, also exhibit, e.g., lasting durability, resistance to pilling, and/or high breathability. 
     Also, by engineering a way to markedly enhance encapsulation of synthetic lofted microfibers  118 , POLARTEC™ Power Air™ fabrics are changing how insulating fabrics will perform over their lifetimes or how the insulating fabrics will retain their performance and thereby increase their longevity. This new fabric construction thus encases lofted fibers  118  within self-contained air pockets  106 . In certain implementations, the lofted fibers  118  are positioned in the air pocket randomly and/or are floating within the air pocket. The air pockets  106  capture and release warm air, while gaining added strength and support from the surrounding knit structure. The structure  106  also serves as a barrier, which prevents loose microfibers from shedding into the environment. The two distinctly contrasting surfaces  106  and  112  of the POLARTEC™ Power Air™ fabric  100  provide markedly wider design versatility, e.g., as compared to most other insulation fabrics. Finally, the symmetrical grid interior  114 ,  116  holds warmth, while the opposite smooth surfaces  110 ,  112  reduce surface drag, thereby to reduce or prevent pilling, and to allow easy layering with other materials. 
     The components  100  and  102  are stitched together in accordance with particular implementations. The components  100  and  102  are stitched together in a manner that reduces and/or avoids stitching within the inlay (i.e. the air pockets  106  containing the lofted fibers  118 ) to prevent the lofted fibers  118  from being trapped or causing them to protrude through the exterior surfaces  110 ,  112 . In certain implementations, the air pockets  106  along the edge of the fabric or adjacent to stitching are provided with less lofted fibers  118  than other air pockets away from an edge or not adjacent to stitching securing the components  100  and  102  together to reduce and/or eliminate trapping of lofted fibers and thereby prevent and/or reduce lofted fibers from protruding through the exterior surfaces  110 ,  112 . 
     For example, referring again to  FIGS.  4 - 9   , a further representative POLARTEC™ Power Air™ fabric product  10  is shown having horizontal positioning (in the main view), with air pockets  20  (seen at a macro level). The air pockets  20  provide encapsulation of lofted fibers, and thermal retention, with filtered microfibers (e.g., with approximately 5 times (i.e., “5.times.”) less shedding of undesirable microfibers, e.g. as compared to the shedding of microfibers by of comparable prior art fabric products). Furthermore, the fabric of the present invention typically has two distinct surfaces, including a symmetrical gridded interior  16  and a smooth outer surface  14 . 
     In use, a representative POLARTEC™ Power Air™ fabric product is well suited for use in cold weather conditions and activities, such as outdoor training, mountain trekking, in urban environments, and is base installations, etc. In can also reduce, or even make unnecessary, the putting on and removing of layers, i.e., as often necessary for maintaining comfort, e.g. in changing conditions and/or during varying degrees of exertion. 
     The improved, POLARTEC™ Power Air™ insulating fabric  10  has a double-knit body  12 , formed with a first, traditional, relatively smooth outside surface  14  and relatively high loft, grid (or gridded) inside surface  16 . POLARTEC™ Power Air™ insulating fabric  10  is a double (weft) knit fabric designed in such a way as to create a composite, three-layer construction, including, but not limited to, relatively flat, smooth outer ‘face’ surfaces  14 , an outer ‘backside’ surface  16  with generally hemispherical or somewhat irregular geometric-like raised areas  17  ( FIG.  4   ), and a middle layer  19  (FIG.  5 ), which consists of multifilament fibers contained between the two outer surface regions  14 ,  16 .™ 
     The double-knit “bubbles”  18  and air spaces  20  of the inside surface  16  of the POLARTEC™ Power Air™ fabric  10  provide an insulating air space equivalent to traditional brushed grid fabric. However, the POLARTEC™ Power Air™ insulating, double-knit fabric is manufactured without a brushing step, which can at least diminish the breaking of fibers, to eliminate (or at least reduce) microfiber pollution, and also to reduce fiber loss in washing, with resultant corresponding reduction in insulation performance. The result is reduction, or elimination, of fiber pollution in wastewater from washing. Additionally, there is a significant reduction in the production of waste fibers during manufacturing with the elimination of mechanical lifting via brushing or knapping. 
     The design and construction of the improved POLARTEC™ Power Air™ double-knit fabric  10  of the disclosure replaces the middle layer of a brushed grid fabric. 
     The POLARTEC™ Power Air™ fabric, provided in different gradients, in order to encourage advantageous movement of moisture through the body of the fabric, or the insulating fabric, may be formed of polypropylene yarns (recognized as a good water carrier, i.e., polypropylene does not hold moisture), or yarns of these or other materials, alone or in blend(s), may also be employed. 
     In some embodiments, the outer surface of at least some yarns forming the fabric POLARTEC™ Power Air™ insulating, double-knit fabric may define channels, e.g. the yarn has a star-shape outer surface contour  24  (see  FIG.  9   ), to encourage/permit moisture movement, where desired. 
     The POLARTEC™ Power Air™ insulating, double-knit fabric may be used, e.g., in insulating outdoor performance apparel to provide a significantly reduced propensity to shed microfibers during the life of the garment, while providing optimum comfort for the wearer. The processing of this fabric excludes the use of mechanical brushing or napping devices to increase insulation value of the material for use in outdoor apparel. Referring to  FIG.  10   , in one representative embodiment, the POLARTEC™ Power Air™ insulating, double-knit fabric  12  is formed into a garment  20 , e.g. a shirt, which, for comfort in chilly or inclement weather, could be worn as a mid-layer, in combination with and between a light weight t-shirt or undershirt  22 , worn against the wearer&#39;s skin, S, and an outer, windbreaker-type jacket  24  worn on over the POLARTEC™ Power Air™ insulating, double-knit fabric garment. 
     Other performance features incorporated into the POLARTEC™ Power Air™ insulating double-knit fabric include: thermal insulating properties (measured as Clo value) achieved by using fibers types and cross-sections that optimize thermal insulation efficiency with minimal added fabric weight. Also, moisture migration properties and fabric moisture retention are managed in a manner to maximize comfort by utilization of fibers with cross-sections that promote accelerated dry times and moisture vapor transport rate. In particular embodiment, the lofted fibers can be formed (e.g. geometrically or materially) to have a particular gradient (e.g., denier) that causes moisture to flow in a particular direction. In addition, pockets of air that add insulation value and air movement (measured as air permeability) for moisture management are created through the integration of alternating raised surfaces  17  ( FIG.  4   ) with the intersection of back and face layers. Also, fiber coatings comprised of polyurethane polymers are incorporated to promote fabric durability (measured as “Martindale abrasion/pilling rating”). Finally, fiber treatments comprised of silicon emulsions are incorporated to modify fiber orientation within the raised fabric structure and increase air volume, in certain implementations. 
     The POLARTEC™ Power Air fabrics thus provide multiple desired qualities that may be described and summarized, for example, as one or more of: “Warm more. Shed Less”; “Air Powered Design”; “Holds More Than Heat”; “It&#39;s Time to Get Knit-Picky”; “Want to catch more than just Air?”; “Harness Your Heat”; “Put Some Power in Your Insulation”; “Regulate Heat. Reduce Impact”; “The Power of Air”, etc. 
     As shown in the examples of  FIGS.  11 A- 13 D , the PowerAir™ fabric can include various versions of the dual-surface double-knit construction with various air encapsulation configurations. 
       FIGS.  11 A- 11 E  show an implementation of POLARTEC™ Power Air fabric with windows and an inlay formed into the circular knit construction. An inlayed fabric  1100  is illustrated in  FIGS.  11 A- 11 E . The inlayed fabric  1100  includes a plurality of windows  1106  formed in an outer layer  1101  of the fabric  1100 . The inner layer  1102 , in contrast, does not include window inlays  1106 . The outer layer  1101  and the inner layer  1102  form a plurality of rows or channels  1104  as shown in  FIGS.  11 C and  11 D . The rows  1104  form elongated air pockets housing intermediate fiber regions  1103  housing fibers  1107  positioned substantially parallel to the inner layer  1102  and the outer layer  1101 . In certain implementations, the fibers  118  are floating within the channels  1104 . The outer knit layer  1101  is formed as a circular knit and the inner knit layer  1102  is formed as a circular knit. 
       FIGS.  12 A- 12 G  illustrate POLARTEC™ Power Air™ fabric with a solid back and face and formed with a double raschel. A double raschel fabric  1200  is shown in  FIGS.  12 A- 12 G . The double raschel fabric  1200  has a solid knit layer  1201  as well as a solid knit layer  1202 . The solid knit layer  1201  and solid knit layer  1202  may be composed of various materials that can include, but are not limited to, polyester, polypropylene, nylon, wool, cellulosic fibers, flame resistant fibers, modacrylic fibers, polyamide fibers or other natural or synthetic fibers in whole or in part, blended or unblended. The solid knit layers  1201  and  1202  encapsulate a plurality of regions of lofted fibers  1203  between them. The lofted fibers  1203  can be comprise polyester fibers, cotton fleeces, rayon, polyamide, flame resistant fibers, but are not limited thereto. The regions of lofted fibers  1203  are separated from one another via spaces  1204 , which comprise encapsulated air regions without any lofted fibers disposed therein. The lofted fibers  1203  extend away from or substantially orthogonal (i.e., in a direction having an orthogonal component) to the solid knit layers  1201  and  1202 . The solid knit layers  1201  and  1202  form a denier gradient, in particular implementations. In certain implementations the knit layers  1201  and  1202  have a finer denier than the lofted fibers  1203 , which assist with moving the water from one layer  1202 , which may be adjacent to a user&#39;s skin, to the lofted fibers  1203  and then to the knit layer  1201  without retaining the water or moister in the encapsulated lofted fibers  1203 . Alternatively or additionally, the knit layers  1201  and  1202  may have a different denier with respect to one another. In certain implementations, the regions of lofted fibers  1203  are configured in a grid array where spaces separate each region from each other region. As demonstrated in  FIG.  12 C , one of the knit layers  1201  can have a corrugated, undulated, or other raised profile, while the opposing knit layer  1202  can have a planar or smoother profile.  FIGS.  12 E and  12 F  further demonstrate in a cross-section view the spaces  1204  separating the lofted fibers  1203  from one another. In certain implementations, the spaces  1204  may be extended lengthwise and form an air channel running from one end of the fabric to another end of the fabric. As demonstrated in  FIGS.  12 F and  12 G , a braided tube  1205  can be positioned in the elongated space  1204  between the encapsulated lofted fibers  1203 . The braided tube  1205  is flexible and stretchable. The braided tube  1205  can include a monofilament, which may be composed at least in part of a material that is distinct from the lofted fibers  1203 . The braided tube  1205  illustrated in  FIG.  12 G  can be incorporated into any space illustrated in other embodiments or implementations of the POLARTEC™ Power Air™ fabric disclosed herein. In particular embodiments, the braided tube  1205  is composed of nylon fibers. The braided tube  1205  can be composed of other materials in accordance with certain implementations. The braided tube  1205  can be composed of a nylon fiber having a denier in the range of 20-100 denier, in certain implementations. In particular, implementations, the denier of the fiber forming the braided tube  1205  may be greater than 100 denier or less than 20 denier. The braided tube can be composed, at least in part, from a monofilament or a multi-filament. The braided tubing provides permits the fiber to be provided with additional airspace with less weight and may be interspersed with regions of the lofted fibers (e.g., lofted fibers  1203 ). The braided tubing  1205  provides air space that can increase insulation, yet provide flexibility and elasticity to the fabric to prolong performance, effectiveness, and durability. In certain implementations, the braided tubing  1205  may be positioned between knit layers  1201  and  1202  in a fabric body provided without lofted fibers. 
       FIGS.  13 A- 13 D  illustrate an implementation of the POLARTEC™ Power Air™ fabric with a solid back and an open face and formed with double raschel. A double raschel knit fabric  1300  is illustrated in  FIGS.  13 A- 13 D  having a first knit layer  1301  comprising a plurality of windows  1306  formed therein. In certain implementations, the windows  1306  may have a constant size across the fabric  1300 . In certain implementations, the windows  1306  may have variable size across the fabric  1300 . The second knit layer  1302  does not include window inlays. The window inlays  1306  are positioned over the space regions  1304  positioned between the lofted fibers encapsulated in air pockets between the knit layer  1301  and  1302 . The window inlays  1306  are positioned in spaces that overlie air spaces between the knit layer  1301  and  1302  rather than being positioned over the lofted fibers  1303 . Accordingly, the lofted fibers  1303  are retained encapsulated between the knit layers  1301  and  1302 , thereby preventing fiber loss and retaining higher insulating performance levels for extended durations. 
     While various embodiments show the air/lofted microfiber encapsulation pockets in a rectangular or square grid, various embodiments can include other geometries, which can include constant or varying pocket sizes. For example, the air/fiber encapsulation pockets of lofted fibers may be larger and/or thicker in a certain region of the fabric than in another region. 
     A number of embodiments of the invention are described above. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, synthetic materials described above may be employed in industrial products, such as rubber tires, plastics, etc. Accordingly, other embodiments are within the scope of the following claims.