Patent Publication Number: US-2015064395-A1

Title: Formed Articles Comprising Carbon And Natural Fibers, Methods Of Manufacture And Use Thereof

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of the filing date of U.S. Provisional Application Ser. No. 61/871,825, filed Aug. 29, 2013, the teachings of which are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to the manufacture of light weight formed articles comprising carbon and natural fibers, and associated method of processing and manufacturing. 
     BACKGROUND 
     Environmentally conscious manufactures may seek to reduce the carbon footprint of their products by use of recycled/reclaimed materials, as well as materials from renewable resources. 
     In the transportation industry, many articles are formed of fiber reinforced composites, in which fibers are generally embedded in a cured resin. In particular, the airline industry makes use of carbon fiber reinforced composite articles for many structural components due to the high strength-to-weight ratio of such materials. 
     The processes of manufacturing carbon fiber reinforced composite articles necessarily creates process scrap. Manufacturing process scrap from the manufacture of carbon fiber reinforced composite articles may include unused (virgin) carbon fiber, as well as carbon fiber with various surface treatments (e.g. bonding agents) and resin impregnation. Such scrap may generally be in the form of trim waste or rejected (defective) formed articles. 
     Furthermore, the carbon fiber reinforced composite article itself similarly becomes scrap at the end of its useful life. End-of-life (EOL) scrap, as opposed to manufacturing scrap, may include carbon fiber embedded in a cured resin which has been subjected to environmental exposure. EOL scrap may include additional components added to the carbon fiber reinforced composite article after manufacture (e.g. coatings, fasteners), as well as contaminants. 
     Processes have been developed to reclaim carbon fiber from fiber reinforced composite articles at the various stages of manufacture, as well as at the end of the article&#39;s useful life. However, given the properties of reclaimed carbon fiber may be considered inferior to virgin carbon fiber, there has been resistance in the airline industry to incorporating such reclaimed carbon fiber back into aircraft components. 
     In the automotive industry, on the other hand, automotive manufactures do not widely utilize virgin carbon fiber. Virgin carbon fiber is generally considered too expensive for economical use, except in limited applications demanding the strength-to-weight ratio of carbon fiber reinforced composite articles. Rather, automotive manufactures have utilized glass fibers for many years, and have more recently made greater use of certain natural fibers, particularly for weight reduction. However, natural fibers often do not offer the physical properties or dimensional stability of glass fibers. 
     What is needed for certain automotive applications is an improved fiber reinforcement which will further reduce weight, as well as provide an increase in physical properties and dimensional stability, without a significant negative cost impact. 
     SUMMARY 
     In one embodiment of the present disclosure, the disclosure provides a fiber mat comprising a first fiber layer, the first fiber layer formed by combining 45-55% by weight of synthetic polymer fibers; 35-45% by weight of natural fibers; and 5-15% by weight of carbon fibers. 
     In another embodiment of the present disclosure, the disclosure provides a fiber mat comprising a core layer sandwiched between first fiber layer and the second fiber layer; the first fiber layer formed by combining 45-55% by weight of synthetic polymer fibers; 35-45% by weight of natural fibers; and 5-15% by weight of carbon fibers; and the second fiber layer formed by combining 45-55% by weight of synthetic polymer fibers; 35-45% by weight of natural fibers; and 5-15% by weight of carbon fibers. 
     In another embodiment of the present disclosure, the disclosure provides a formed article comprising a molded substrate formed from a fiber mat, the fiber mat comprising a first fiber layer formed by combining 45-55% by weight of synthetic polymer fibers; 35-45% by weight of natural fibers; and 5-15% by weight of carbon fibers. 
    
    
     
       FIGURES 
       The above-mentioned and other features of this disclosure, and the manner of attaining them, will become more apparent and better understood by reference to the following description of embodiments described herein taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a cross-sectional view of a first fiber mat according to the present disclosure; 
         FIG. 2  is a cross-sectional view of a second fiber mat according to the present disclosure; 
         FIG. 3  is a flow diagram of a manufacturing process to make a formed article from the fiber mat of  FIG. 1  or  2 ; and 
         FIG. 4  is a flow diagram of an alternative manufacturing process to make a formed article from the fiber mat of  FIG. 1  or  2 . 
     
    
    
     DETAILED DESCRIPTION 
     It may be appreciated that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention(s) herein may be capable of other embodiments and of being practiced or being carried out in various ways. Also, it may be appreciated that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting as such may be understood by one of skill in the art. 
     Referring now to the figures,  FIG. 1  shows a first exemplary embodiment of a planar fiber mat  10  according to the present disclosure. As shown fiber mat  10  comprises a first fiber layer  12 . Fiber layer  12  may particularly comprise fibers of different material compositions as follows:
         45-55% by weight of fiber layer  12  may be formed from polymer fibers, and more particularly, synthetic polymer fibers. Exemplary synthetic polymer fibers may include polypropylene fibers, which may further include fibers of polypropylene homopolymer(s) and/or polypropylene copolymer(s) (e.g. polypropylene-maleic anhydride copolymer). The polymer fibers may have a length of 8 mm to 40 mm, and more particularly 12 mm to 25 mm. The polymer fibers may particularly have a melt flow index of 0.1-10 g/10 min. determined according to ASTM D 1238-13 at 230° C. under a load of 2.16 kg, and more particularly 0.6-6 g/10 min. determined according to ASTM D 1238-13 at 230° C. under a load of 2.16 kg.   35-45% by weight of the fiber layer  12  may be formed from natural fibers. Exemplary natural fibers may include one or more of kenaf, flax, jute hemp, sisal and cellulose. The natural fibers may have a length of 8 mm to 40 mm, and more particularly 12 mm to 25 mm; and   5-15% by weight of the fiber layer  12  may be formed from carbon fibers. The carbon fibers may further include virgin and/or reclaimed carbon fibers. The carbon fibers may have a length of 8 mm to 40 mm, and more particularly 12 mm to 25 mm.       

     Fiber layer  12  may be particularly formed as a planar sheet via the process disclosed in U.S. Patent Application Publication No. 2010/0261014, entitled Utilization of Recycled Carbon Fiber, the teachings of which are hereby incorporated by reference in its entirety. Fiber layer  12  may also be particularly formed as a planar sheet via a dry-laid non-woven fabric manufacturing process, such as an airlay process. Fiber layer  12  may particularly have an area weight of 500-1,000 grams/square meter (gsm). 
     In one exemplary embodiment, made using the process disclosed in U.S. Patent Application Publication No. 2010/0261014, a fiber layer  12  having a 840 gsm weight may be formed from the following:
         50% polypropylene-maleic anhydride copolymer fiber comprising 95-99% by weight polypropylene and 1-5% by weight maleic anhydride as a comonomer to the polypropylene;   40% natural fiber of which 38% is a combination of kenaf, jute and flax, and 2% are cellulose fibers; and   10% reclaimed carbon fiber.       

     In addition to fiber layer  12 , fiber mat  10  may further comprise second and third fiber layers  14 ,  16 , particularly of nonwoven scrim having an area weight of 30-100 gsm, and more particularly having an area weigh of 50-75 gsm, which are positioned on opposing front and rear sides of the first fiber layer  12 , respectively. The nonwoven scrim may be particularly formed of polyethylene terephthalate, which may be used to promote bonding to the fiber mat  10  to a decorative cover, as well as promote bonding to subsequently formed ribs and fastening locations, as explained in greater detail below. 
     As compared to a fiber mat which does not make use of a fiber layer  12  containing carbon fiber, fiber mat  10  according to the present disclosure may exhibit the following increases in tensile strength and heat distortion temperature physical properties. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                   
                 Area 
                 Tensile 
                 Heat 
               
               
                   
                 Weight 
                 Strength 1   
                 Distortion 
               
               
                 Composition 
                 (gsm) 
                 (MPa) 
                 Temp 2  (° C.) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 50% PP (w/ma); 50% natural 
                 1,200 
                 16.0 
                 123.1 
               
               
                 fiber. 3  (Baseline) 
               
               
                 50% PP (w/ma), 8% carbon 
                 700 
                 17.5 
                 123.2 
               
               
                 fiber, 42% natural fiber 
               
               
                 50% PP (w/ma), 8% carbon 
                 1060 
                 19.0 
                 154.3 
               
               
                 fiber, 42% natural fiber 
               
               
                 50% PP (w/ma), 15% carbon 
                 600 
                 22.0 
                 145.2 
               
               
                 fiber, 35% natural fiber 
               
               
                 50% PP (w/ma), 15% carbon 
                 900 
                 29.0 
                 153.1 
               
               
                 fiber, 35% natural fiber 
               
               
                   
               
               
                 Footnotes: 
               
               
                   1 ASTM D638-10, 50 mm/min. 
               
               
                   2 ASTM D648-07. 
               
               
                   3 50% polypropylene-maleic anhydride copolymer fiber comprising 95-99% by weight polypropylene and 1-5% by weight maleic anhydride as a comonomer to the polypropylene. 
               
            
           
         
       
     
     In a second embodiment of fiber mat  10  as shown in  FIG. 2 , fiber mat  10 ′ may comprise a core  18  sandwiched between two opposing fiber layers  12   a,    12   b.  Core  18  may have an area weight of 300-1,000 gsm and a thickness of 0.5 to 1.5 mm. The core  18  may be formed of shoddy, cardboard, honeycomb and polyurethane foam. As compared with the first embodiment, fiber layers  12   a,    12   b  may each have an area weight of 100-600 gsm. 
     As shown in  FIG. 3 , fiber mat  10  may be used to manufacture a formed article  70 . Article  70  may be formed by first heating the fiber mat  10  between two opposing heated platens  20 ,  22  to a temperature of 375-425° C. for a period of 45-60 seconds, or otherwise until the fiber mat  10  reaches a temperature of 400° C. Once the fiber mat  10  is sufficiently heated, the fiber mat  10  may be placed between two opposing halves  32 ,  34  of a first heated compression mold  30 . Compression mold may be heated to a temperature of 60-120° C. The mold  30  may be closed and the fiber mat  10  formed into a substrate  40 , during which time the synthetic polymer fibers may flow under compression to form substrate  40 . The substrate  40  may then cool and be removed from compression mold  30 . Substrate  40  may have a thickness 0.5-2 mm, and more particularly have a thickness of 1-1.5 mm. 
     Thereafter, the substrate  40  may placed between two opposing halves  52 ,  54  of second compression mold  50 , along with decorative cover layer  60 , which may be in the form of a sheet. Thereafter, the second compression mold  50  may be closed to compression mold and laminate the decorative cover layer  60  to the substrate  40  to form formed article  70 , with the adhesive layer of the decorative cover layer  60  bonding to outer scrim layer  14  of the substrate  40 . 
     Decorative cover layer  60  may formed of polyvinyl chloride (PVC), thermoplastic urethane (TPU), and thermoplastic olefin (TPO). Decorative cover layer may have a thickness in a range of 0.5-2.5 mm, and may be more particularly formed of a polyvinyl chloride (PVC), thermoplastic urethane (TPU), and thermoplastic olefin (TPO) outer skin overlying a cushion layer of polyvinyl chloride (PVC) or polyolefin foam. Decorative cover layer may include a grained outer surface and an adhesive coated inner surface to bond to the substrate  40 . 
     In alternative embodiments, decorative cover layer  60  may be introduced to first compression mold  30  along with fiber mat  10  to form article  70  in one step, here with a single mold  30 . 
     Also in alternative embodiments, it should be understood that decorative layer  60  is not necessarily required, and the formed article  70  may merely comprise substrate  40 . It should also be understood that fiber mat  10 ′ may be substituted for fiber mat  10 ′ shown in the process of  FIG. 3 . 
     In another alternative embodiment of the process of  FIG. 3 , as shown in  FIG. 4 , the compression mold  30  may be configured as an injection-compression mold  30 ′, which is configured to receive resin from a polymer delivery unit  36 , such as a screw plastication unit of an injection molding machine used for injection-compression molding. Here, after compression molding of the fiber mat  10 , polymer delivery unit  38 , in conjunction with a suitable runner  38  in mold half  34 , may deliver polymer material to the backside of the compression molded substrate to mold a plurality of elongated reinforcement (stiffening) ribs  42  which extend along a length of the substrate  40 ′, as well as fastening locations (e.g. screw bosses, dog houses), to the backside of the substrate  40 ′. 
     Formed article  70  may particularly be a trim member for a motor vehicle such as an interior or exterior trim panel such as a side trim panel (e.g. door trim panel); a package tray, a headliner, an instrument panel, an upper or lower instrument panel close-out panel, a console, a trunk liner, a door bolster, a knee bolster and a seat back, 
     While a preferred embodiment of the present invention(s) has been described, it should be understood that various changes, adaptations and modifications can be made therein without departing from the spirit of the invention(s) and the scope of the appended claims. The scope of the invention(s) should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents. Furthermore, it should be understood that the appended claims do not necessarily comprise the broadest scope of the invention(s) which the applicant is entitled to claim, or the only manner(s) in which the invention(s) may be claimed, or that all recited features are necessary.