PATENT DOCUMENT

Publication Number: US-10718067-B1
Application Number: US-201715655740-A
Country: US
Kind Code: B1

Title: Magnetic strands for fabric items

Abstract:
Items such as fabric-based items may include magnetic strands. Magnetic strands may be formed using extrusion equipment. To form single component magnetic strands, first and second feed hoppers may respectively feed a base polymer and a magnet masterbatch to an extruder. The magnet masterbatch may include particles of a rare-earth alloy or other magnetic materials in a polymer blend. The extruder may push the base polymer and magnet masterbatch through a spinneret. To form bicomponent magnetic strands, a first extruder may push a base polymer and magnet masterbatch through a first set of openings in a spinneret, while a second extruder may push an additional polymer through a second set of openings in the spinneret. Bicomponent magnetic strands may have a magnetic core and non-magnetic sheath, may have a non-magnetic core and magnetic sheath, or may have other suitable configurations.

Claims:
What is claimed is: 
     
       1. A method for forming fabric, comprising:
 with a first feed hopper, feeding a magnet masterbatch to a feed path, wherein the magnet masterbatch includes magnetic particles in a polymer material; 
 with a second feed hopper, feeding a base polymer to the feed path, wherein the base polymer mixes with the magnet masterbatch in the feed path; 
 with the extruder, receiving a mix of the magnet masterbatch and the base polymer from the feed path and extruding the mix of the magnet masterbatch and the base polymer through an array of openings to produce magnetic strands; 
 with the first feed hopper, adjusting a ratio of the magnet masterbatch to the base polymer so that the ratio varies along a length of the magnetic strands; and 
 intertwining the magnetic strands. 
 
     
     
       2. The method defined in  claim 1  wherein the magnetic particles comprise rare-earth magnetic particles. 
     
     
       3. The method defined in  claim 2  wherein the rare-earth magnetic particles comprise neodymium alloy particles. 
     
     
       4. The method defined in  claim 1  wherein the base polymer comprises a material selected from the group consisting of: polyamide, polyester, polyethylene, polypropylene, and polyurethane. 
     
     
       5. The method defined in  claim 1  wherein the polymer material comprises a material selected from the group consisting of: polyamide, polyester, polyethylene, polypropylene, and polyurethane. 
     
     
       6. The method defined in  claim 1  wherein intertwining the magnetic strands comprises intertwining the magnetic strands with non-magnetic strands, wherein the magnetic strands form a magnetic portion of the fabric. 
     
     
       7. The method defined in  claim 1  wherein the magnetic strands have at least one non-magnetic segment that is formed entirely of the base polymer. 
     
     
       8. The method defined in  claim 1  wherein the magnetic strands comprise single component magnetic strands. 
     
     
       9. The method defined in  claim 1  further comprising:
 with a third feed hopper, feeding an additional polymer to an additional extruder; and 
 with the additional extruder, pushing the additional polymer through the array of openings to produce the magnetic strands. 
 
     
     
       10. The method defined in  claim 9  wherein the magnetic strands comprise bicomponent magnetic strands. 
     
     
       11. The method defined in  claim 10  wherein a first component of the bicomponent magnetic strands comprises the magnet masterbatch and the base polymer and wherein a second component of the bicomponent magnetic strands comprises the additional polymer. 
     
     
       12. The method defined in  claim 11  wherein the additional polymer forms a core in the bicomponent magnetic strands and the magnet masterbatch and the base polymer form a sheath in the bicomponent magnetic strands. 
     
     
       13. The method defined in  claim 11  wherein the magnet masterbatch and the base polymer form a core in the bicomponent magnetic strands and the additional polymer forms a sheath in the bicomponent magnetic strands. 
     
     
       14. A method for forming strands for fabric, comprising:
 with first and second feed hoppers, feeding first and second polymers to a common feed path, wherein the second polymer contains magnetic particles and wherein the first and second polymers mix in the common feed path to produce a magnetic material; 
 with a first extruder, receiving the magnetic material from the common feed path and extruding the magnetic material through a first set of openings in a spinneret to form a first component in a magnetic strand; 
 with a second extruder, extruding non-magnetic material through a second set of openings in the spinneret to form a second component in the magnetic strand; and 
 intertwining the magnetic strand with other strands, wherein the magnetic strand has a non-magnetic segment in which a cross-section of the magnetic strand is comprised entirely of the non-magnetic material. 
 
     
     
       15. The method defined in  claim 14  wherein the first component forms a core in the magnetic strand and the second component forms a sheath in the magnetic strand. 
     
     
       16. The method defined in  claim 14  wherein the second component forms a core and the first component forms a sheath in the magnetic strand. 
     
     
       17. A method for forming magnetic strands, comprising:
 with a first feed hopper, feeding a first polymer to a first extruder; 
 with a second feed hopper, feeding a second polymer to the first extruder, wherein the second polymer is mixed with magnetic particles and wherein the first polymer, the second polymer, and the magnetic particles are mixed together in a common feed path before being fed to the first extruder; 
 with a third feed hopper, feeding a third polymer to a second extruder; and 
 with the first and second extruders, pushing the first, second, and third polymers through a spinneret to form bicomponent magnetic strands, wherein an amount of the magnetic particles in one of the bicomponent magnetic strands varies along its length. 
 
     
     
       18. The method defined in  claim 17  wherein the magnetic particles comprise rare-earth magnetic particles. 
     
     
       19. The method defined in  claim 18  wherein the first, second, and third polymers are selected from the group consisting of: polyamide, polyester, polyethylene, polypropylene, and polyurethane.

Description:
This application claims the benefit of provisional patent application No. 62/381,991, filed Aug. 31, 2016, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to magnetic materials, and more particularly, to items that include magnetic materials. 
     BACKGROUND 
     Magnetic material is used to form components such as permanent magnets and soft magnetic materials. Magnetic materials may be difficult to incorporate into certain items such as fabric-based items and other items without creating undesirable visible and tactile artifacts. If care is not taken, the items into which permanent magnets and other magnetic structures are incorporated may be overly bulky, stiff, or unsightly. 
     SUMMARY 
     Items such as electronic devices, fabric-based items, and other items may include strands of magnetic material. Magnetic material may be used in forming clasps, closures for seams in fabric-based items, flaps and other structures with positions that may be sensed using magnetic sensors, and other structures. 
     Magnetic strands may include magnetic material formed from particles of a rare-earth alloy or other magnetic particles in a polymer blend. Magnetic strands may be formed using extrusion equipment. 
     Strands of magnetic material may be single component magnetic strands that are formed using one extruder or may be bicomponent magnetic strands that are formed using two extruders. A single component magnetic strand may include magnetic particles in a polymer blend. A bicomponent magnetic strand may include a magnetic cores surrounded by a non-magnetic sheath or may have a non-magnetic core surrounded by a magnetic sheath. 
     To form single component magnetic strands, first and second feed hoppers may respectively feed a base polymer and a magnet masterbatch to an extruder. The magnet masterbatch may include particles of a rare-earth alloy or other magnetic materials in a polymer blend. The extruder may push the base polymer and magnet masterbatch through a spinneret. 
     To form bicomponent magnetic strands, a first extruder may push a base polymer and magnet masterbatch through a first set of openings in a spinneret, while a second extruder may push an additional polymer through a second set of openings in the spinneret. Bicomponent magnetic strands may have a core-and-sheath type shape or may have other suitable configurations depending on the shape, size, and arrangement of openings in the spinneret. 
     If desired, the rate at which the magnet masterbatch that is fed to the extruder may be adjusted to change the ratio of magnetic material to non-magnetic material in the strands. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative system having one or more items with magnetic strands in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative item with magnetic strands in accordance with an embodiment. 
         FIG. 3  is a diagram showing how magnetic strands may be used in fabric in accordance with an embodiment. 
         FIG. 4  is a cross-sectional view of an illustrative magnetic strand in accordance with an embodiment. 
         FIG. 5  is a cross-sectional side view of an illustrative magnetic strand that includes a non-magnetic core and a magnetic sheath in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of an illustrative magnetic strand that includes a magnetic core and a non-magnetic sheath in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of an illustrative yarn formed from multiple magnetic strands in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of an illustrative yarn with magnetic and non-magnetic strands in accordance with an embodiment. 
         FIG. 9  is a diagram of illustrative extrusion equipment that may be used to form single component magnetic filaments in accordance with an embodiment. 
         FIG. 10  is a diagram of illustrative extrusion equipment that may be used to form bicomponent magnetic filaments in accordance with an embodiment. 
         FIG. 11  is a flow chart of illustrative steps involved in forming fabric with one or more magnetic strands in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Magnetic material may be used in forming electronic devices, may be used in forming accessories such as covers, straps, and bags that are associated with electronic devices, may be used in forming fabric for electronic devices and accessories, may be used in forming fabric that is incorporated into seating, furniture, building structures, and other items, and/or may be used in forming other items. Configurations in which magnetic material is used in forming items based on one or more strands of magnetic material may sometime be described herein as an example. The strands of material may be monofilaments of material and/or may be multifilament strands such as strands of yarn. Strands may be processed by twisting, texturizing, or otherwise modifying or combining strands of material to form strand-based items. Strand-based items may be formed by weaving, knitting, or braiding strands of material to form different types of fabric. 
     Magnetic material may be magnetized to form permanent magnets. Permanent magnets may interact with each other. For example, permanent magnets may be arranged to attract each other or to repel each other. Soft magnetic materials can also be attracted by permanent magnets. Electromagnets may be electrically configured to either attract or repel a permanent magnet. Unmagnetized magnetic material (e.g., ferromagnetic material or ferrimagnetic material that has not been magnetized by application of an external magnetic field to form a permanent magnet) may also interact with permanent magnets and electromagnets. For example, a permanent magnet may attract a fabric or other structure formed from strands of unmagnetized magnetic material based on a rare earth alloy such as a neodymium alloy (e.g., NdFeB). 
     An illustrative system that includes items with magnetic structures (e.g., electromagnetics, permanent magnets, unmagnetized magnetic material, etc.) is shown in  FIG. 1 . As shown in  FIG. 1 , system  10  may include one or more items such as items  12 A and  12 B that include magnetic structures. Items such as items  12 A and  12 B may be electronic devices (e.g., cellular telephones, tablet computers, laptop computers, watches, pendant devices, other wearable devices, or other electronic equipment), may be parts of electronic devices or accessories for electronic devices (e.g., covers for portable electronic devices, straps for electronic devices, earphones, bags, covers, sleeves, or other structures that form part of electronic equipment or that are used in conjunction with electronic equipment), may be part of furniture, seating, clothing, a vehicle, a building, a kiosk, or any other items. 
     System  10  may include multiple parts that interact with each other (e.g., using magnetic forces). For example, system  10  may include a first item (e.g., item  12 A) such as a portable electronic device and a second item (e.g., item  12 B) such as a cover for the portable electronic device. In this type of scenario, items (structures)  12 A and  12 B are separable and are often referred to as forming different items. These components may also be used together as part of a unified system (i.e., a system formed from a device with a cover). If desired, system  10  may be a single item that is formed from multiple structures that interact with each other (e.g., using magnetic forces). For example, system  10  may be an item such as a fabric enclosure. In this type of arrangement, item  12 A may form a main body portion of the enclosure and item  12 B may form a flap for a pocket in the main body portion. Other configurations may also be used for system  10  (e.g., arrangements with more than three magnetically interacting items, etc.). The configuration of  FIG. 1  is merely illustrative. 
     As shown in  FIG. 1 , items such as items  12 A and  12 B may include fabric such as fabric  14 A and fabric  14 B and may therefore sometimes be referred to as forming a fabric-based item or items. Fabric  14 A and/or fabric  14 B may include intertwined strands of material. Some or all of the strands in fabric  14 A and/or  14 B may be magnetic strands that include magnetic material such as rare-earth magnetic materials or other magnetic materials. Fabric  14 A and  14 B may also include dielectric strands (e.g., strands formed entirely from glass, plastic, or other dielectric), conductive strands (e.g., strands with magnetic or non-magnetic metal cores or coatings), and/or strands of other materials. 
     If desired, items  12 A and  12 B may include components  16 A and  16 B such as permanent magnets, electromagnets, structures formed from unmagnetized magnetic material, and non-magnetic components. During operation, magnetic structures in item  12 A (e.g., permanent magnets, electromagnets, structures formed from unmagnetized magnetic material, magnetic strands, magnetic components, and other magnetic structures) may attract, may repel, may generate a magnetic field that is sensed using a magnetic sensor, may sense a magnetic field, or may otherwise interact with magnetic structures in item  12 B (e.g., permanent magnets, electromagnets, structures formed from unmagnetized magnetic material, magnetic strands, magnetic components, and other magnetic structures). 
     If desired, components  16 A and  16 B may include circuitry. The circuitry of components  16 A and  16 B may include input-output devices such as buttons, touch sensors, light-based sensors such as light-based proximity sensors, force sensors, environmental sensors such as temperature sensors and humidity sensors, other sensors, status indicator lights and other light-based components such as light-emitting diodes for forming displays and other light-emitting structures, vibrators or other haptic output devices, etc. The circuitry of components  16 A and  16 B may also form control circuitry (e.g., processors, touch sensor circuits, etc.). 
     Fabric  14 A and  14 B may, if desired, include conductive strands of material that are coupled to control circuitry formed from processors and other circuits in components  16 A and  16 B, respectively. The conductive strands may serve as signal paths that carry signals between input-output components and control circuitry and may serve as capacitive touch sensor electrodes and other conductive structures in item  10 . This is, however, merely illustrative. If desired, fabric  14 A and fabric  14 B may not include any conductive strands. 
       FIG. 2  is a schematic diagram showing illustrative components that may be used in forming items such as item  12 A and  12 B of  FIG. 1 . As shown in  FIG. 2 , item  12  may include fabric  14  such as strands of magnetic material and/or other material. Magnetic material may also be used to form other structures in item  12 . 
     Item  12  may include sensors  18 . Sensors  18  may include magnetic sensors (e.g., Hall effect sensors, giant magnetoresistance sensors, or other sensors that measure magnetic fields). Sensors  18  may also include light-based sensors (e.g., light-based proximity sensors that emit light and detect reflected light, ambient light sensors that detect ambient light, image sensors, etc.), microphones, accelerometers and other sensors for detecting motion and position, temperature sensors, pressure sensors, strain gauges, touch sensors, and other sensors for detecting user input and for measuring environmental conditions. 
     Control circuitry  22  may include microprocessors, microcontrollers, digital signal processors, volatile and non-volatile memory and other storage, application-specific integrated circuits, and other circuitry for controlling the operation of item  12 . Control circuitry  22  may use information from sensors  18 , and other components  24  for controlling the operation of item  12 . 
     Electromagnets  20  may be controlled by circuitry  22  to attract or repel magnetic structures. Electromagnets  20  may, for example, be used to open and close an enclosure along a seam, may be used to secure flaps or other foldable edge structures, may be used to close and open straps, etc. 
     Components  24  may include input-output devices such as switches, touch screens, displays, light-emitting diodes, speakers, vibrators, haptic output devices, motors, keyboards, track pads, pointing devices, peripheral components, and other devices for gathering input from a user or the environment surrounding item  12  while supplying output (e.g., output for a user or an item associated with item  12 ). 
     All or part of the components of item  12  of  FIG. 2  may be incorporated into one or more items in system  10  (see, e.g., illustrative items  12 A and  12 B of  FIG. 1 ). Items such as item  12  of  FIG. 2  may include one or more fabric portions (see, e.g., fabric  14 A and  14 B of  FIG. 1 ) and may therefore sometimes be referred to as strand-based items or fabric-based items. In other situations, some or all of a given item  12  may not include fabric. For example, a first item without fabric may interact with a second item that includes fabric. 
     As shown in  FIG. 3 , item  12  may include fabric  14 . Fabric  14  may be woven fabric, knit fabric, braided material, felt, or other suitable fabric formed from intertwined strands of material. In the illustrative arrangement of  FIG. 3 , fabric  14  is woven fabric that is formed from strands  32 . Strands  32  may include warp strands  26  and weft strands  28 . Strands  32  may include magnetic portions and non-magnetic portions. For example, warp strands  26  may include non-magnetic portions  26 N and magnetic portions  26 M. Weft strands  28  may include non-magnetic portions  28 N and magnetic portions  28 M. Magnetic portions  26 M and  28 M may extend throughout the entire length of the strand or may only be located in a portion of the strand. If desired, magnetic portions  26 M and  28 M of strands  32  may be located near one another to form a magnetic region such as magnetic region  30 . 
     If desired, fabric  14  may also include conductive strands of material. Conductive strands in fabric  12  may be used in conveying signals between control circuitry  22  and electrical components  24  (see, e.g.,  FIG. 2 ). 
       FIGS. 4, 5, and 6  are cross-sectional side views of illustrative fibers (sometimes referred to as monofilaments) that may be used in forming magnetic yarn. 
     In the example of  FIG. 4 , magnetic strand  32  may include particles  36  of magnetic material (e.g., neodymium alloys or other rare-earth magnetic materials, non-rare-earth ferromagnetic or ferromagnetic magnetic materials, or other magnetic particles). Magnetic particles  36  may be hard magnets (e.g., with a particle size between 0.001 mm and 0.050 mm or other suitable size) or may be soft magnets (e.g., with a particle size between 20 nm and 0.050 mm or other suitable size). Hard magnetic materials retain their magnetism even after removal of an applied magnetic field. Soft magnetic materials are easily magnetized and demagnetized and may be used to form temporary magnets. A polymer blend such as polymer blend  34  (sometimes referred to as a polymer binder, a matrix, or supporting material) or other binder material may be used to support magnetic particles  36  (i.e., magnetic particles  36  may be embedded within blend  34 ). Examples of polymer materials that may be used to form blend  34  include polyamides (e.g., Nylon 6, Nylon 66, Nylon 12, etc.), polyester (polyethylene terephthalate (PET)), polyethylene, polypropylene, polyurethane, or other thermoplastic materials. Other polymers may be used, if desired. Strands of the type shown in  FIG. 4  may sometimes be referred to as single component strands. A single component strand may be formed by extruding a single polymer (e.g., polymer  34  in which magnetic particles  36  are embedded) to form a filament. 
     In the example of  FIG. 5 , strand  32  has a core portion such as fiber core  38  and has an exterior layer such as exterior layer  40 . Fiber core  38  may be a polymer core or other non-magnetic core and exterior layer  40  (sometimes referred to as a sheath) may be a layer of magnetic material (e.g., polymer  34  with embedded rare-earth alloy particles or other magnetic material particles  36 ). 
     In the example of  FIG. 6 , strand  32  includes a magnetic fiber core  38  and a non-magnetic outer layer  40 . Fiber core  38  of  FIG. 6  may include magnetic material particles  36  embedded in polymer  34 . Exterior layer  40  may be a non-magnetic polymer layer. Strands of the type shown in  FIGS. 5 and 6  may sometimes referred to as bicomponent strands. A bicomponent strand may be formed by extruding two polymers (e.g., a first polymer such as polymer  34  in which magnetic particles  36  are embedded and a second polymer such as polymer core  38  of  FIG. 5  or polymer sheath  40  of  FIG. 6 ) to form a filament. Examples of polymer materials that may be used to form core  38  and/or outer layer  40  include polyamides (e.g., Nylon 6, Nylon 66, Nylon 12, etc.), polyester (polyethylene terephthalate (PET)), polyethylene, polypropylene, polyurethane, or other thermoplastic materials, and any other suitable polymer. 
     If desired, strands  32  may include one or more additional layers of material (e.g., a central core, an outer coating, one or more intermediate layers interposed between the coating and the core, etc.). The layers of strands  32  may include one or more magnetic layers (e.g., layers of polymer blend containing embedded magnetic particles), may include solid magnetic alloy (e.g., rare-earth magnetic alloys such as neodymium alloys), may include dielectric (e.g., inorganic dielectric such as glass, oxides, nitrides, oxynitrides, etc.), organic dielectric such as polymers, ceramic, and/or other dielectric material, may include metal (e.g., non-magnetic metal), or other materials. Multilayer strand structures such as the structures forming strand  32  of  FIGS. 5 and 6  may be used along the entire length of strands  32  or may be used along one or more discrete segments of strands  32 . 
     Monofilament strands such as strands  32  of  FIGS. 4, 5, and 6  may be intertwined along their lengths to form multifilament strands (i.e., yarn).  FIGS. 7 and 8  show examples of yarns that have been formed using magnetic strands. Strands  32  for yarn  60  may be intertwined by spinning, braiding, or by otherwise intertwining strands  32 . In the example of  FIG. 7 , all of the strands  32  in yarn  60  are magnetic to form magnetic yarn  60 . 
     In the example of  FIG. 8 , yarn  60  includes both magnetic strands  32 M and non-magnetic strands  32 N and may therefore be magnetic. Strands  32 M and  32 N may be spun together in a yarn spinning tool or may otherwise be intertwined to form yarn  60  (e.g., using braiding equipment, etc.). 
     Illustrative equipment that may be used in forming magnetic structures such as single component magnetic strands  32  of the type shown in  FIG. 4  is shown in  FIG. 9 . As shown in the example of  FIG. 9 , strands  32  may be processed using extrusion equipment  42 . Extrusion equipment  42  may include an extruder such as extruder  48  (e.g., a single screw or twin screw extruder) that pushes polymers through small holes in a spinneret such holes  62  in spinneret  50 . As the polymer is pushed through spinneret  50 , continuous polymer filaments  32  exit the array of openings  62 . 
     Extrusion equipment  42  may form fibers  32  via melt spinning, which is sometimes described herein as an example. In arrangements where extrusion equipment  42  forms fibers  32  via melt spinning, the polymer that forms fibers  32  may be melted, extruded, and then solidified by cooling upon exiting spinneret  50 . 
     Openings  62  in spinneret  50  may have a circular cross-sectional shape to produce strands  32  with circular cross-sectional shapes, or openings  62  may have any other suitable cross-sectional shape (oval, rectangular, trilobal, pentagonal, octagonal, etc.). 
     Polymers may be fed to extruder  48  via feed hoppers  52 - 1  and  52 - 2 . Feed hopper  52 - 1  may feed base polymer  34 ′ to extruder  48 , and hopper  52 - 2  may feed magnet masterbatch  64  to extruder  48 . Magnet masterbatch  64  may include magnetic particles  36  embedded in a polymer blend  34 ″. Magnet masterbatch  64  may include, for example, about 20% magnetic particles by volume (or about 70% magnetic particles by weight), or may include any other suitable ratio of magnetic particles  36  to masterbatch polymer  34 ″. 
     Base polymer  34 ′ and magnet masterbatch  64  may be fed into a common feed path  46  before entering extruder  48 . If desired, base polymer  34 ′ and magnet masterbatch  64  may be solid or semi-solid in hoppers  52 - 1  and  52 - 2  and may be melted in extruder  48  by a heat source before reaching spinneret  50 . 
     Strands  32  that exit spinneret  50  may be single component fibers of the type shown in  FIG. 4 . In particular, base polymer  34 ′ and masterbatch polymer  34 ″ may mix in feed path  46  and extruder  48  to form polymer blend  34  of  FIG. 4 . The polymer blend  34  may have magnetic particles  36  to form magnetic strands  32 . 
     By feeding both non-magnetic base polymer  34 ′ and magnet masterbatch  64  separately into feed path  46 , extruding equipment  42  may control the ratio of magnet masterbatch  64  to base polymer  34 ′. If desired, extruding equipment  42  may change the ratio of magnet masterbatch  64  to non-magnetic base polymer  34 ′ during the extrusion process to create strands  32  with varying amounts of magnetic particles  36  along the length of strands  32 . The ratio of magnetic material  64  to non-magnetic material  34 ′ may, for example, be adjusted by adjusting the rate at which feed hopper  52 - 2  feeds magnetic material  64  to extruder  48 . Some portions of strands  32  may be formed entirely of non-magnetic base polymer  34 ′ and may not include may magnetic particles  36  (e.g., by feeding only base polymer  34 ′ to extruder  48  during the extrusion process). This is, however, merely illustrative. If desired, strands  32  may include uniform amounts of magnetic particles  36  relative to base polymer  34 ′ along the length of strands  32 . 
     If desired, magnetic strands  32  may be formed by extruding material from a single feed hopper. For example, magnetic material  64  may be fed to extruder  48  on its own (e.g., without base polymer  34 ′). Arrangements in which magnetic material  64  is extruded together with a base polymer such as base polymer  34 ′ are sometimes described herein as an example. 
     After exiting spinneret  50 , strands  32  may be processed further, if desired. For example, a stretching process may be used to stretch strands  32 . Strands  32  may, for example, be stretched to achieve the desired monofilament diameter (e.g., 0.02 mm to 2.0 mm or other suitable diameter). 
     Illustrative equipment that may be used in forming magnetic structures such as bicomponent magnetic strands  32  of the type shown in  FIGS. 5 and 6  is shown in  FIG. 10 . As shown in the example of  FIG. 10 , extrusion equipment  42  may include two extruders such as extruder  48 - 1  and extruder  48 - 2  (e.g., single screw or twin screw extruders) that push polymers through small holes in a spinneret such holes  62  in spinneret  50 . As the polymers are pushed through spinneret  50 , continuous, bicomponent polymer filaments  32  exit the array of openings  62 . 
     Extruder  48 - 1  may be used to extrude the magnetic component of strands  32  (e.g., magnetic sheath  40  of  FIG. 5 , magnetic core  38  of  FIG. 6 , or other suitable magnetic component of strand  32 ). Extruder  48 - 2  may be used to extrude the non-magnetic component of strands  32  (e.g., non-magnetic core  38  of  FIG. 5 , non-magnetic sheath  40  of  FIG. 6 , or other suitable non-magnetic component of strands  32 ). The magnetic component of strands  32  may be formed by extruding polymers  34 ′ and  34 ″ (which contains magnetic particles  36 ) from feed hoppers  52 - 1  and  52 - 2 , respectively, through extruder  48 - 1  and through a first set of openings  62  in spinneret  50 . The non-magnetic component of strands  32  may be formed by extruding polymer  54  from feed hopper  52 - 3  through extruder  48 - 2  and through a second set of openings  62  in spinneret  50 . 
     If desired, color may be imparted to strands  32  using a color masterbatch such as color masterbatch  68 . Color masterbatch  68  may include a colored pigment such as pigment  72  that is mixed with a polymer such as polymer  70  (e.g., polyamide, polyester, polyethylene, polypropylene, polyurethane, etc.). Colored pigment  72  may be concentrated pigment that imparts color to surrounding polymer when melted and mixed with the surrounding polymer. If desired, a colored dye may be used instead of or in addition to pigment  72 . 
     In the example of  FIG. 10 , feed hopper  52 - 4  feeds color masterbatch  68  to extruder  48 - 2 , where it mixes with and imparts color to polymer  54 . In arrangements where polymer  54  forms a sheath in strands  32 , pigment  72  may impart color to the sheath of strands  32  by imparting color to polymer  54 . In arrangements where magnetic material forms a sheath in strands  32 , the magnetic material may, if desired, be imparted with color using a color masterbatch of the type shown in  FIG. 10 . In general, color may be imparted to any portion of strands  32  by incorporating pigments or dye from a color masterbatch in the polymer that forms that portion of strands  32 . The example of  FIG. 10  in which non-magnetic material  54  is colored is merely illustrative. 
     Openings  62  in spinneret  50  of  FIG. 10  may be configured to produce bicomponent fibers of the type shown in  FIGS. 5 and 6 . In particular, openings  62  may include a central opening for producing a core such as core  38  of  FIGS. 4 and 5  and a ring shaped opening surrounding the central opening for producing a sheath such as sheath  40  of  FIGS. 4 and 5 . This is, however, merely illustrative. If desired, openings  62  in spinneret  50  may have other configurations for producing other types of bicomponent fibers (e.g., side-by-side bicomponent fibers, core and sheath bicomponent fibers where the core is off-center, segmented pie bicomponent fibers, striped bicomponent fibers, trilobal bicomponent fibers, or any other suitable type or shape of bicomponent fiber). 
     As in the example of  FIG. 9 , by feeding both non-magnetic base polymer  34 ′ and magnet masterbatch  64  separately into feed path  46 , extruding equipment  42  of  FIG. 10  may control the ratio of magnet masterbatch  64  to base polymer  34 ′. If desired, extruding equipment  42  may change the ratio of magnet masterbatch  64  to non-magnetic base polymer  34 ′ during the extrusion process to create strands  32  with varying amounts of magnetic particles  36  along the length of strands  32 . The ratio of magnetic material  64  to non-magnetic material  34 ′ may, for example, be adjusted by adjusting the rate at which feed hopper  52 - 2  feeds magnetic material  64  to extruder  48 - 1 . Some portions of strands  32  may be formed entirely of non-magnetic base polymer  34 ′ and may not include may magnetic particles  36  (e.g., by feeding only base polymer  34 ′ to extruder  48  during the extrusion process). This is, however, merely illustrative. If desired, strands  32  may include uniform amounts of magnetic particles  36  along the length of strands  32 . Base polymer  34 ′ and masterbatch polymer  34 ″ may mix in feed path  46  and in extruder  48 - 1  to form polymer blend  34  (see, e.g., blend  34  of  FIGS. 5 and 6 ). The polymer blend  34  may have magnetic particles  36  to form magnetic strands  32 . 
     Strands  32  that exit spinneret  50  may be bicomponent fibers of the type shown in  FIGS. 5 and 6  or may be any other suitable type of bicomponent fiber having a magnetic component. The example of  FIG. 10  in which a first component in strands  32  (e.g., the component formed from polymers  34 ′ and  34 ″ in extruder  48 - 1 ) is magnetic and a second component in strands  32  (e.g., the component formed from polymer  54  in extruder  48 - 2 ) is non-magnetic is merely illustrative. If desired, both components in bicomponent strands  32  of  FIG. 10  may be magnetic (e.g., by including magnetic particles in polymer  54  or by feeding a second magnet masterbatch into extruder  48 - 2  with polymer  54 ). Arrangements where more than two extruders are used to produce strands with more than two components may also be used, if desired. 
     The examples of  FIGS. 9 and 10  in which magnetic strands are formed by mixing a magnet masterbatch and feeding the magnet masterbatch with a base polymer into an extruder is merely illustrative. If desired, magnetic strands may be formed by extruding polymer with magnetic particles from a single feed hopper. The use of a magnet masterbatch and base polymer may help ensure that the resulting strands  32  have the desired flexibility and robustness. It also allows equipment  42  to modulate the ratio of magnetic particles to polymer in strands  32 . 
       FIG. 11  is a flow chart of illustrative steps involved in forming an item with magnetic strands of the type shown in  FIGS. 1-8 . 
     At step  100 , a magnet masterbatch such as magnet masterbatch  64  of  FIG. 9  or  FIG. 10  may be mixed. The magnet masterbatch may contain a desired ratio of magnetic particles  36  to polymer blend  34 ″. The ratio of magnetic particles to polymer (by volume) may be 1 to 5, 1 to 10, 3 to 10, 4 to 10, or other suitable ratio. 
     At step  102 , the magnet masterbatch may be processed using extrusion equipment  42  of the type shown in  FIG. 9  or  FIG. 10 . To produce single component magnetic strands, polymers including the magnet masterbatch and a base polymer may be extruded through a single extruder and pushed through an array of openings in a spinneret to produce single component magnetic strands  32 . To produce bicomponent magnetic strands, polymers including the magnet masterbatch and a base polymer may be extruded through a first extruder, while an additional polymer may be extruded through a second extruder. Each extruder may respectively push the first and second components through a respective set of openings in a spinneret to produce bicomponent magnetic strands. The bicomponent magnetic strands may be core-and-sheath bicomponent fibers or may be any other suitable configuration depending on the cross-sectional shape of the spinneret openings. 
     At step  104 , strands  32  may be intertwined to form fabric (e.g., fabric  14  of  FIGS. 1, 2 , and  3 ). Step  104  may include weaving, knitting, warp knitting, braiding, or any other suitable method of intertwining strands to form fabric. 
     At optional step  106 , magnetizing equipment may be used to magnetize magnetic material in strands  32 . Step  106  may be performed before step  104  so that the magnetic material in strands  32  is magnetized before being incorporated into fabric  14  or step  106  may be performed after step  104  so that strands  32  are magnetized after being incorporated into fabric  14 . Once magnetized, the magnetic material can form a permanent magnet. The permanent magnet may be sensed by a magnetic sensor, may interact with another permanent magnet or other magnetic structure to form part of a clasp or closure, or may be used in forming other structures for item  12 . Following the formation of the fabric, magnetizing equipment e.g., a permanent magnet or electromagnet) may apply a magnetic field that is sufficient to magnetize all of a fabric or fabric-based item, a portion of the fabric or fabric-based item, or any other portion of a strand-based item). 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20170720
Publication Date: 20200721
Grant Date: 20200721
Priority Date: 20160831
Inventors: WANG, LIMING
ZHU, HAO
BHATIA, RIMPLE
Assignee: APPLE INC
CPC Classifications: [{"code": "D02G3/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "D03D15/507", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F1/0533", "inventive": true, "first": false, "tree": "[]"}, {"code": "D01F6/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "D01F1/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "D01D5/34", "inventive": true, "first": true, "tree": "[]"}, {"code": "C08J3/226", "inventive": true, "first": false, "tree": "[]"}, {"code": "C08J3/203", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F1/053", "inventive": true, "first": false, "tree": "[]"}, {"code": "D02G3/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "D01D5/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "D01D5/34", "inventive": true, "first": true, "tree": "[]"}, {"code": "D02G3/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "D03D15/0055", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F1/053", "inventive": true, "first": false, "tree": "[]"}, {"code": "D02G3/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "D01D5/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "D02G3/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "D01D5/34", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 71611815