Patent Publication Number: US-2012040124-A1

Title: Reinforced walkway system

Description:
FIELD OF THE INVENTION 
     The disclosure relates to walkway systems, and, more particularly, to a reinforced walkway system with thermal protection, superior dimensional stability and high reflectivity and high emissivity properties. 
     BACKGROUND 
     There currently exists commercially available roof walkway systems that are designed to protect single-ply roof membrane from foot traffic damage, thermal degradation, dragged or wheeled objects and usage or damage from dropped tools. One such system is the Tuff Trac® Roof Walkway System available from The Biltrite Corporation, Waltham, Mass. 02453. Because such systems are secured to the roof of the structure, they are exposed to the elements, particularly extreme temperatures, for extended periods, depending on the geographic location of the structure. Particularly in more southerly and westerly areas, extreme heat and exposure to ultraviolet rays can cause dimensional instability, and UV damage to the material from which the system is constructed. In areas of frequent precipitation, traction and water channeling concerns arise. 
     Accordingly, need exists for a roof walkway system which possesses improved thermal protection, dimensional stability, high reflectivity and high emissivity properties, and channels water efficiently. 
     SUMMARY 
     Disclosed is a reinforced walkway system comprising an embossed walkway performance layer having a composite reinforcement layer thermally bonded thereto. The performance layer may be manufactured from fibrous recycled thermoplastic or rubber scrap that creates dimensional stability within the polymer formulation thereof and may have a pattern embossed thereon, such as a herringbone pattern, that allows for superior water drainage. The reinforcement layer may comprise a high temperature reinforcing composite which is thermally applied to the underside of the performance layer to prevent delamination therefrom during the product life and which provides a medium that maintains the dimensional stability of the embossed performance layer at high temperatures. 
     According to one aspect of the disclosure, an article of manufacture comprises a walkway performance layer comprising a polymer composite and a reinforcement layer secured thereto, the reinforcement layer being a composite layer formed of a plurality of materials. In one embodiment, the walkway performance layer may comprise any of polyolefin (TPO), Polyvinylchloride (PVC), and Elvaloy/Polyvinylchloride optionally mixed with other additives such as UV protection or mineral fillers. In another embodiment, the reinforcement layer may comprise a plurality of different materials chosen to maintain the dimensional stability of the embossed walkway at high temperatures. 
     According to another aspect of the disclosure, a method of forming a reinforced walkway system comprises: a) providing a walkway performance layer comprising a polymer composite; b) providing a composite reinforcement layer formed of a plurality of materials; c) thermally fusing the performance layer and the reinforcement layer together to form a fused layer therebetween, while substantially simultaneously embossing the performance layer. 
    
    
     
       DESCRIPTION THE DRAWINGS 
         FIG. 1  is a perspective view of the walkway system  5  illustrating an embossment formed into the performance layer thereof; 
         FIGS. 2A-G  illustrates conceptually perspective cut-away views of the multiple layers of the walkway system  5 A-G in accordance with various embodiments disclosed herein; and 
         FIG. 3  is a conceptual illustration of a thermal forming process used to create the walkway systems disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     A reinforced walkway system  5  in accordance with the disclosure comprises an embossed walkway layer  10  and a composite reinforcement layer  30 . A thermal fusion layer  20  is formed at the juncture of layers  10  and  30  during the manufacturing process. In another embodiment, layer  30  has a polymer adhesive layer  40  and release layer  50  formed there under to facilitate peel and stick attachment of system  5  to a roof structure. The system  5  is designed to protect single-ply roof membrane from foot traffic damage, thermal degradation, dragged or wheeled objects and usage or damage from dropped tools. System  5  offers superior dimensional stability versus non-reinforced walkway forms. 
     Performance Layer 
     In one embodiment, layer  10  may comprise a mineral filled, recycled thermoplastic such as one or more of polyolefin (TPO), Polyvinylchloride (PVC), or Elvaloy/Polyvinylchloride blend. Layer  10  may comprise both post industrial and post consumed thermoplastic or rubber materials. Specifically, layer  10  may be manufactured from fibrous recycled thermoplastic or rubber scrap that creates dimensional stability within the polymer formulation by adding structural integrity. Layer  10  maybe manufactured from recycled roofing membrane resin which is mixed via a direct compounding process by itself or with prime resins and other additives such as UV protection or mineral fillers to promote the proper longevity of the product in outdoor weathering conditions. In one embodiment, layer  10  may be implemented with a commercially available material, such as the Tuff Trac® Roof Walkway System available from The Biltrite Corporation, Waltham, Mass. 02453. 
     Layer  10  may be designed with a herringbone embossment on the upward or exterior surface thereof, as illustrated in  FIG. 1 , that allows for superior water drainage. Although some embossment surfaces used in the trade have interconnected sections, the channel design of the herringbone embossment allows for the more effective water drainage of the surface area of the walkway. Typically, water ponding occurs in low lying areas of low slope single-ply roofing structures so water drainage is important to maintaining a sure foot surface for roof top traffic. 
     In an alternative embodiment, other embossing patterns may be formed into performance layer  10 , including Diamond Plate embossment, Pyramid embossment, or similar patterns which provide both improved traction and water channeling characteristics. 
     Composite Reinforcement Layer 
     Layer  30 , in one embodiment, comprises a high temperature reinforcing composite which is thermally applied to the backside of the walkway performance layer  10  to prevent delamination of the performance layer during the product life. The composite reinforcing layer  20 , which in one embodiment may be fabric reinforced, provides a backing medium that maintains the dimensional stability of the embossed walkway at high temperatures (defined as greater than 158 Fahrenheit up to 250 Fahrenheit). 
       FIGS. 2A-G  illustrates conceptually perspective, cut-away views of the multiple layers of the walkway system in accordance with various embodiments disclosed herein, the layers in such figures not being shown to their true dimensions. In  FIGS. 2A-G , the herringbone or other embossment pattern in layer  10  is not illustrated for simplicity purposes. 
     Referring to  FIG. 2A , a walkway system  5 A is illustrated as comprising a performance walkway layer  10 A, a thermal fusion layer  20 A and a composite reinforcement layer  30 A. Layer  10 A may have the composition described herein. Layer  20 A represents the thermal fusion juncture of embossed walkway layer  10 A with composite reinforcement  30 A as formed using manufacturing processes described herein. In system  5 A, composite reinforcement layer  30 A comprises a polyolefin film  31 A, an acrylic adhesive layer  32 A, a fiberglass fabric  33 A, an acrylic adhesive  34 A, and a Mylar polyester film  35 A formed into a single composite layer. 
     Referring to  FIG. 2B , a walkway system  5 B is illustrated. Walkway system  5 B is similar in construction, composition and function to system  5 A of  FIG. 2A , except that Mylar polyester film  35 A layer is replaced with a reflective foil layer  35 B of layer  30 B, as illustrated. 
     Referring to  FIG. 2C , a walkway system  5 C is illustrated. Walkway system  5 C is similar in construction, composition and function to system  5 A of  FIG. 2A , except that composite layer  30 A has been replaced with composite layer  30 C which comprises a Polyolefin film  31 C, a Fiberglass or Polyester fabric  32 C, and Polyethylene film  33 C, as illustrated. 
     Referring to  FIG. 2D , a walkway system  5 D is illustrated. Walkway system  5 D is similar in construction, composition and function to system  5 A of  FIG. 2A , except that the polyolefin film  31 A of composite layer  30 A has been replaced with a polyvinylchloride film  31 D of composite layer  30 D, as illustrated. 
     Referring to  FIG. 2E , a walkway system  5 E is illustrated. Walkway system  5 E similar in construction, composition and function to system  5 B of  FIG. 2B , except that the polyolefin film  31 B of composite layer  30 B has been replaced with a polyvinylchloride film  31 E of composite layer  30 E, as illustrated. 
     Referring to  FIG. 2F , a walkway system  5 F is illustrated as comprising a performance walkway layer  10 F, a thermal fusion layer  20 F and a composite reinforcement layer  30 F. Layer  10 F may have the composition similar to other layers  10  as, described herein. 
     Layer  20 F represents the thermal fusion juncture of embossed walkway layer  10 F with composite reinforcement  30 F as formed using manufacturing processes described herein. In system  5 F, composite reinforcement layer  30 F comprises either a polyolefin or polyvinyl chloride film  31 F, a fiberglass or polyester fabric  32 F, and a Mylar polyester film or reflective foil  35 F, as illustrated. In addition system  5 F comprises a layer  40 F of extruded or coated modified butyl rubber or thermoplastic polymer adhesive disposed on the under surface of layer  30 F. Adjacent layer  40 F is a removable layer  50 F comprising a silicon coated release liner. The system  5 F as illustrated in  FIG. 2F  facilitates rapid and easy you stick application of the system to the roof surface. 
     Referring to  FIG. 2G , a walkway system  5 G is illustrated. A walkway system  5 G is illustrated as comprising a performance walkway layer  10 G, a thermal fusion layer  20 G and a composite reinforcement layer  30 G. Layer  10 G may be formed from a composition comprising approximately 40%-75% fibrous recycled roof membrane. Layer  20 G represents the thermal fusion juncture of embossed walkway layer  10 G with composite reinforcement  30 G as formed using manufacturing processes described herein. In system  5 G, composite reinforcement layer  30 G comprises a polypropylene film  31 G, a polyester fabric  32 G, and another layer of polypropylene film  33 G formed into a single composite layer. 
     The various system embodiments illustrated in  FIGS. 1-2G  may be manufactured using a thermal forming process illustrated by the conceptually in  FIG. 3 . Specifically, the reinforcement layer  30 , as described herein, and the walkway performance layer  10 , also as described herein, are simultaneously supplied from a film roller  60  and extruded roller  62 , respectively, to a pair of embossing rollers  64  and  66  where the layers  10  and  20  are thermally fused to form layer  20  and embossed substantially simultaneously, resulting in a finished laminated walkway system  5  which is spooled to idle roller  68 . Note in this process that composite layer  30  and performance layer  10  have been previously formed prior to spooling onto rollers  60  and  62 , respectively, for formation of layer  20  and system  5 . In the case of system  5 F, layers and  30 F,  40 F and  50 F have been previously formed together and spooled prior to their joining with layer  10 F. In some embodiments, the width of the finished laminated walkway system may be about 60 inches. 
     System Benefits 
     System  5  as disclosed herein provides a sure foot pathway that is slip resistant due to the deep herringbone embossment that will not wrinkle or exhibit distortion at high temperature extremes. 
     System  5  maybe applied to existing roof membrane surfaces with direct thermal bonding. In one embodiment, a reinforced walkway comprising system  5  is designed with a welding edge that is not reinforced to allow for undisturbed thermal bonding of walkway to the roof membrane. The non-reinforced edge is supported from dimensional movement by the underlying roof membrane. 
     System  5  may be manufactured with a brightly colored safety edge applied to the outside edges of the walkway surface for easy identification of the high raised area of the protective walkway. 
     As noted previously, system  5  maybe made with a high temperature reinforcing composite to provide a high reflective and emissive layer for thermal protection of the underlying roof membrane. 
     It will be obvious to those recently skilled in the art that modifications to the article of manufacture and process disclosed here in may occur, including substitution of various materials within the compounds of layers and different layer configurations, without parting from the true spirit and scope of the disclosure.