Patent Document

BACKGROUND 
       [0001]    (a) Field 
         [0002]    The subject matter disclosed generally relates to slip resistant sheet materials for roofing and to methods for manufacturing slip resistant sheet materials for roofing. More particularly, the subject matter disclosed relates to a weather-resistive barrier for a roofing structure, and especially to a reinforced roof underlayment having a slip resistant feature. 
         [0003]    (b) Related Prior Art 
         [0004]    Roofing structures for buildings typically include an underlayment positioned between a roof support deck and an overlayment. The overlayment, such as asphalt shingles, tiles, wooden shakes, slate tiles metal roofing, or the like is intended to provide protection from external weather conditions like wind, rainwater, and snowmelt. In order to further protect against moisture and other elements which may pass under the overlayment, the underlayment is installed over the roof deck and under the underlayment to provide an added waterproof barrier. The additional moisture protection provided by the underlayment is particularly necessary with tile roofs, where gaps often exist between the tiles where moisture can pass through. The underlayment also serves the function of providing a seal around roofing fasteners used to affix the tiles to the roof support deck. 
         [0005]    Typically, underlayment may include a polymeric material that is affixed and/or coated to a base sheet for providing a barrier to weather conditions. A limitation of such underlayment is that these polymeric materials can be very slippery in both wet and dry conditions. Installation of the underlayment and the subsequent roofing material can therefore be problematic as workers may need to walk across or work upon the polymeric material coated or affixed to the base sheet. This decreases the commercial attractiveness of such underlayment for high pitch roof applications or in climates characterized by wet or humid conditions. 
         [0006]    Accordingly, there is a need for a roofing underlayment having an improved resistance to deterioration from exposure to external elements which prevents a person from slipping while moving about on the roofing underlayment and for an improved method of manufacturing the same. 
       SUMMARY 
       [0007]    According to an embodiment, there is provided a slip resistant sheet material for roofing having an upper side and a lower side. The slip resistant sheet material comprises: a closed-weave woven base layer having a top surface facing in a same direction as the upper side; and a first thermoplastic layer affixed to the top surface; wherein projections are formed in the same direction as the upper side at corresponding locations in the base layer and the first thermoplastic layer thereby providing slip resistance on the upper side. 
         [0008]    According to an aspect, the projections are defined on the upper side and corresponding depressions are defined on the lower side. 
         [0009]    According to an aspect, the slip resistant sheet material has a thickness and wherein the projections and corresponding depressions are defined transversely to the thick of the slip resistant sheet material. 
         [0010]    According to an aspect, the slip resistant sheet material is adapted for a worker to walk thereon in his footwear and whereby, when the worker walks or stands on the slip resistant sheet material, there exists friction between the footwear and a combination comprising the projections and the first thermoplastic layer thereby providing slip resistance. 
         [0011]    According to an aspect, the closed-weave woven base layer further comprises a bottom surface opposite the top surface and the slip resistant sheet material further comprises a second thermoplastic layer affixed to the bottom surface. 
         [0012]    According to an aspect, the first thermoplastic layer and the second thermoplastic layer are respectively directly affixed to the top surface and to the bottom surface without use of an adhesive or another intermediate layer. 
         [0013]    According to an aspect, at least one of the first thermoplastic layer and the second thermoplastic layer is vapor impermeable. 
         [0014]    According to an aspect, at least one the first thermoplastic layer and the second thermoplastic layer is a film-forming polymer. 
         [0015]    According to an aspect, at least one the first thermoplastic layer and the second thermoplastic layer comprise(s) at least one of: polyethylene and polypropylene. 
         [0016]    According to an embodiment, there is provided a method for manufacturing a slip resistant sheet material for roofing having an upper side and a lower side. The method comprises: providing a closed-weave woven base layer having a top surface facing in a same direction as the upper side; affixing a first thermoplastic layer to the top surface; and after affixing first thermoplastic layer to the top surface, embossing the base layer and the first thermoplastic layer to form projections in the same direction as the upper side at corresponding locations in the base layer and the first thermoplastic layer thereby providing slip resistance on the upper side. 
         [0017]    According to an aspect, the embossing is performed at ambient temperature. 
         [0018]    According to an aspect, the embossing comprises embossing the base layer and the first thermoplastic layer with an engraved roller. 
         [0019]    According to an aspect, the closed-weave woven base layer further comprises a bottom surface opposite the top surface and the method further comprises affixing a second thermoplastic layer to the bottom surface. 
         [0020]    According to an aspect, the affixing the first thermoplastic layer and the second thermoplastic layer comprises respectively directly affixing the first thermoplastic layer and the second thermoplastic layer to the top surface and to the bottom surface without use of an adhesive or another intermediate layer. 
         [0021]    According to an aspect, the affixing the first thermoplastic layer and the second thermoplastic layer comprises respectively extruding a film-forming polymer thereby producing the first thermoplastic layer and the second thermoplastic layer. 
         [0022]    According to an aspect, the method further comprises respectively bonding the first thermoplastic layer and the second thermoplastic layer with the top surface and to the bottom surface. 
         [0023]    According to an aspect, the extruding a film-forming polymer comprises extruding at least one of: polyethylene and polypropylene. 
         [0024]    According to an embodiment, there is provided a slip resistant sheet material for roofing having a thickness and being adapted for a worker to walk thereon in his footwear. The slip resistant sheet material comprises: a base layer; and a thermoplastic layer affixed to the base layer; wherein the base layer and the thermoplastic layer define projections and corresponding depressions transversely to the thickness of the slip resistance sheet material and whereby, when the worker walks or stands on the slip resistant sheet material, there exists friction between the footwear and a combination comprising the projections and the thermoplastic layer thereby providing slip resistance. 
         [0025]    The following terms are defined below. 
         [0026]    The term “slip resistant sheet material” is intended to mean a sheet material provided with an additional means for increasing the slip resistance and thereby increasing safety of those walking on roofs, or on any surfaces, on which the slip resistance sheet material is installed before installation of an overlayment. 
         [0027]    The term “closed-weave woven” is intended to mean yarns or threads that are normally tightly interlaced at a right angle to form a fabric or a sheet material. The method in which these yarns or threads are interwoven affects the characteristics of the fabric or of the sheet material. The yarns or threads that are tightly interlaced may also be at an angle different than the right angle. 
         [0028]    The term “thermoplastic layer” is intended to mean an elastic and flexible layer, made of a thermoplastic material, to be affixed to at least one of the top surface and bottom surface of a closed-weave woven. The “thermoplastic layer” may provide a weather-resistant barrier which prevents moisture and other external elements from passing through the slip resistant sheet material. 
         [0029]    Features and advantages of the subject matter hereof will become more apparent in light of the following detailed description of selected embodiments, as illustrated in the accompanying figures. As will be realized, the subject matter disclosed and claimed is capable of modifications in various respects, all without departing from the scope of the claims. Accordingly, the drawings and the description are to be regarded as illustrative in nature and not as restrictive and the full scope of the subject matter is set forth in the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    Further features and advantages of the present disclosure will become apparent from the following detailed description, taken in combination with the appended drawings, in which: 
           [0031]      FIG. 1  is an elevation view of a slip resistant sheet material for roofing in accordance with an embodiment; 
           [0032]      FIG. 2  is an enlarged, fragmentary, cross-sectional view of the slip resistant sheet material for roofing of  FIG. 1 ; 
           [0033]      FIG. 2 a    is another enlarged, fragmentary, cross-sectional view of the slip resistant sheet material for roofing of  FIG. 1 ; 
           [0034]      FIG. 2 b    is yet another enlarged, fragmentary, cross-sectional schematic view of the slip resistant sheet material for roofing of  FIG. 1 ; 
           [0035]      FIG. 2 c    is an enlarged, fragmentary, cross-sectional schematic view of the slip resistant sheet material for roofing where only the base layer and the first thermoplastic layer are present; 
           [0036]      FIG. 3  is an exploded, perspective view of the slip resistant sheet material for roofing of  FIG. 1 ; 
           [0037]      FIG. 4  is an elevation view of a slip resistant sheet material for roofing in accordance with another embodiment; 
           [0038]      FIG. 5  illustrates a method for manufacturing a slip resistant sheet material for roofing in accordance with another embodiment; 
           [0039]      FIG. 6  is a perspective view of slip resistant sheet materials for roofing being installed on an exemplary roof structure in accordance with another embodiment; 
           [0040]      FIG. 7  is a perspective view showing the slip resistant sheet materials for roofing of  FIG. 6  in a later stage of the installation process; and 
           [0041]      FIG. 8  illustrates a process for manufacturing a slip resistant sheet material for roofing in accordance with another embodiment. 
       
    
    
       [0042]    It will be noted that throughout the appended drawings, like features are identified by like reference numerals. 
       DETAILED DESCRIPTION 
       [0043]    There is disclosed herein various embodiments of a slip resistant sheet material for roofing and of a method for manufacturing a slip resistant sheet material for roofing. 
         [0044]    Referring now to the drawings, and more particularly to  FIG. 1 , there is shown an elevation view of a slip resistant sheet material  10  for roofing in accordance with an embodiment. The slip resistant sheet material  10  for roofing has an upper side  15  and a lower side  17 . The slip resistant sheet material  10  for roofing further includes a base layer  12  which defines a top surface  14  and a bottom surface  16  ( FIG. 2 ). The top surface  14  faces in a same direction as the upper side  15 . 
         [0045]    According to an embodiment, base layer  12  comprises a closed-weave woven which is referred herein to as a closed-weave woven base layer  12 . According to another embodiment, the base layer  12  comprises a non-woven fibrous material such as a spunbond polyester substrate. 
         [0046]    According to an embodiment, the closed-weave woven base layer  12  includes yarns of a first direction  18  and yarns of a second direction  20  that are interspersed with the yarns of the first direction  18 . As better shown in  FIGS. 2, 2   a ,  2   b  and  2   c , which is an enlarged, fragmentary, cross-sectional view of the slip resistant sheet material  10  for roofing of  FIG. 1 , and in  FIG. 3 , which is an exploded, perspective view of the slip resistant sheet material  10  for roofing of  FIG. 1 , the slip resistant sheet material  10  for roofing further includes thermoplastic first and second layers  22 A,  22 B respectively affixed to the top surface side  14  and the bottom surface  16  of the closed-weave woven base layer  12  for providing a weather-resistant barrier. Still referring to  FIGS. 2, 2   a  and  3 , there is shown that a first thermoplastic layer  22 A is affixed to the top surface  14  of the closed-weave woven and a second thermoplastic layer  22 B is affixed to the bottom surface  16  of the closed-weave woven base layer  12 . 
         [0047]    As shown in  FIGS. 1-3 , the closed-weave woven base layer  12  and the first and second thermoplastic layers  22 A,  22 B are embossed to form an embossed pattern  24 . The embossed pattern  24  has a plurality of projections  26  that outwardly extends from the first thermoplastic layer  22 A and a plurality of corresponding depressions  28  that inwardly extends from the second thermoplastic layer  22 B for providing slip resistance. The projections  26  of the embossed pattern  24  along with the first thermoplastic layer  22 A provide an anti-skid surface/enhanced friction surface/slip resistant surface. 
         [0048]    The embossed pattern  24  increases the slip resistance and thereby increasing safety of those walking on roofs on which the slip resistant sheet material  10  is installed before installation of an overlayment  36  ( FIG. 7 ). 
         [0049]    According to  FIGS. 1-3 , there is shown that the plurality of projections  26  and the plurality of corresponding depressions  28  are regularly spaced within the embossed pattern  24  such as to define a specific mosaic or pattern, such as pattern  25 . However, it is to be noted that the plurality of projections  26  and the plurality of corresponding depressions  28  may be irregularly spaced within the embossed pattern  24  as long as it increases the slip resistance and thereby increases safety of those walking on roofs on which the slip resistant sheet material  10  is installed before installation of the overlayment  36 . 
         [0050]    The embossed pattern  24  includes a texture formed by a plurality of features that are raised and or sunken with respect to the closed-weave woven base layer  12  and the first and second thermoplastic layers  22 A,  22 B. For example, the texture can include a plurality of protrusions or projections  26  and a plurality of corresponding depressions  28  (i.e., cavities, voids) in the closed-weave woven base layer  12  and the first and second thermoplastic layers  22 A,  22 B. The texture of the embossed pattern  24  may be of varying heights or depths or can be substantially the same height or depth. Example of heights and depths of the texture include between about 0.01 mm to 10 mm. The texture can be disposed randomly or can be configured as a uniform or repeated pattern, such as pattern  25 . Where the texture is disposed as an array of uniform or repeating configurations, examples may include straight lines, a cross-hatch pattern, a chevron pattern, a checked pattern, a company logo, dots, and the like. The texture can include raised and/or sunken features that are adjacent to each other or spaced apart from each other providing various densities. Examples include where the texture includes between 1 feature to 100 features per cm 2  of the slip resistant sheet material  10 . Additionally, the features of the texture can have the same shape or can have varying shapes such as square, triangular, circular, ovular, obround, rectangular, random, or any other suitable shape configured to form the anti-skid surface. 
         [0051]    In accordance with embodiments, the slip resistant sheet material  10  may include only one thermoplastic layer, a first and a second thermoplastic layers, or a plurality of different thermoplastic layers, some providing weather-resistant barrier, some other providing UV-resistant barrier, microbial properties, heat resistant properties and the like. It is to be noted that all the thermoplastic layers and the closed-weave woven base layer  12  need to be embossed to form the embossed pattern  24 . This configuration will provide the safety of those walking on roofs. 
         [0052]    In accordance with an embodiment, the thermoplastic layer or the plurality of thermoplastic layers  22 A,  22 B may include a film-forming polymer. 
         [0053]    In accordance with an embodiment, the thermoplastic layer or the plurality of thermoplastic layers  22 A,  22 B comprise(s) polyethylene, polypropylene or a mixture of polyethylene and polypropylene. 
         [0054]    In accordance with an embodiment, the yarns of the first direction  18  and the yarns of the second direction  20  are substantially flat, but can adopt any other cross-sectional configurations. 
         [0055]    The thermoplastic layers  22 A,  22 B (first thermoplastic layer  22 A and second thermoplastic layer  22 B) are normally affixed to both the upper and the top surface  14  and the bottom surface  16  of the closed-weave woven base layer  12 , as shown in the slip resistant sheet material  10  for roofing of  FIGS. 2 and 3 . 
         [0056]    Now referring to  FIG. 4  and in accordance with another embodiment, the closed-weave woven base layer  12  may be formed of yarns of a first gauge  30  of material having a tensile strength sufficient to resist tearing when exposed to tensile loads from various directions. The yarns of the first gauge  30  are normally the yarns of the first direction  18  and the yarns of the second direction  20 . More specifically, the slip resistant sheet material  10  for roofing includes the closed-weave woven base layer  12 , which includes yarns of the first direction  18  and yarns of the second direction  20 . The closed-weave woven base layer  12  may further includes yarns of a second gauge  32 , interspersed within the closed-weave woven base layer  12  with the yarns of the first direction  18  (as shown in  FIG. 4 ) and/or with the yarns of the second direction  20 . The yarns of the second gauge  32  include a gauge that is greater than the first gauge. As better shown in  FIG. 4 , the yarns of the second gauge  32  are interspersed in the closed-weave woven base layer  12  at a given interval with the yarns of the first direction  18 . 
         [0057]    In accordance with an embodiment, the yarns of the second gauge  32  of the closed-weave woven base layer  12  are parallel to each other. In the closed-weave woven base layer  12 , the spacing between the parallel yarns of the second gauge is substantially equal. The yarns of the second gauge  32  of the closed-weave woven base layer  12  may also be perpendicular to each other. 
         [0058]    Still referring to  FIG. 4 , there is shown an elevation view of the closed-weave woven base layer  12  of the slip resistant sheet material  10  for roofing in accordance with an embodiment. In  FIG. 4 , a first group of yarns of the first gauge are in a first direction (yarns of the first direction  18 ), a second group of yarns of the first gauge are in a second direction (yarns of the second direction  20 ) perpendicular to the first direction and a third group of yarns of the second gauge  32  are in the direction parallel to the yarns of the first direction  18 . Also, the yarns of the second gauge  32  may be interspersed at the given interval in at least one of the first and second directions for providing an additional slipping resistance in addition to the embossed pattern  24  for preventing a person from slipping while moving on the slip resistant sheet material  10  for roofing. It is to be noted that the given interval is a multiple of 18 yarns in an embodiment, as shown in  FIG. 4  and referred to as X1. In other embodiments the multiple may be 6 yarns, 9 yarns, 12 yarns, 15 yarns, 36 yarns, 72 yarns, 90 yarns, or any given interval of yarns (not shown) such as to further prevent slipping from a worker. Thus, according to different embodiments, the given interval may be a multiple of any suitable number. 
         [0059]    In accordance with an embodiment, the given interval may be a mix of at least two given intervals. For instance, for allowing a worker to walk on a roofing structure without sliding, the slip resistant sheet material  10  for roofing may include a first group of three yarns of the second gauge  32  interspersed at a given interval of 6 yarns of the yarns of the first direction  18  in the closed-weave woven base layer  12  and another yarn of the second gauge  32 , distant from the first group of three yarns of the second gauge  32 , at another given interval of 72 yarns of the yarns of the first direction  18 . 
         [0060]    According to another embodiment, the given interval is one of: a regular given interval and an irregular given interval. As another example, a first group of three yarns of the second gauge  32  may intersperse the closed-weave woven base layer  12  at a first quarter of the closed-weave woven base layer  12 , a second group of three yarns of the second gauge  32  may intersperse the closed-weave woven base layer  12  at a first half of the closed-weave woven base layer  12  and a third group of three yarns of the second gauge  32  may intersperse the closed-weave woven base layer  12  at a second quarter of the closed-weave woven base layer  12 . 
         [0061]    It is also to be noted that the yarns of the first direction  18  and the yarns of the second direction  20  are tightly interwoven. The yarns of the first direction  18  and the yarns of the second direction  20  of the closed-weave woven base layer  12  may be formed of a thermoplastic polymer, such as polypropylene, polyethylene, polyester, nylon or other similar materials. However, it is to be noted that the yarns of the first direction  18  and the yarns of the second direction  20  of the closed-weave woven base layer  12  may be of any suitable material that has strength sufficient to resist tearing when exposed to tensile loads from various directions. 
         [0062]    The yarns of the first direction  18  and the yarns of the second direction  20  are interwoven as shown in  FIGS. 1-4 , by way of example, to provide a closed-weave woven base layer  12  having an improved tensile strength not achievable with solid film of material. The orientation of the yarns of the first direction  18  and the yarns of the second direction  20  may also be selected to optimize their tensile strength. 
         [0063]    The yarns of the first gauge  30  (i.e., the yarns of the first direction  18  and the yarns of the second direction  20 ) and the yarns of the second gauge  32  may comprise any cross-sectional shape and size, depending upon the desired tensile characteristics of the closed-weave woven base layer  12 . For example, the yarns of the first gauge  30  may be interwoven fibers as shown in  FIG. 2 , may be cross-laminated polyethylene tape, or may include any other interwoven configuration. The size of the yarn of the first gauge  30  may be approximately between 800 Denier to 1,000 Denier. The size of the yarn of the second gauge  32  may be approximately between 1,000 Denier and 12,000 Denier. However, the size of the yarns of the first gauge  30  and the size of the yarns of the second gauge  32  may be of any suitable size allowing the formation of a tight closed-weave woven base layer  12 . 
         [0064]    Referring to  FIGS. 2 and 3 , the first and second thermoplastic layers  22 A,  22 B affixed to both the top surface  14  and the bottom surface  16  of the closed-weave woven base layer  12  provide a weather-resistant barrier which prevents moisture and other external elements from passing through the slip resistant sheet material  10  for roofing. An exemplary embodiment for the first and second thermoplastic layers  22 A,  22 B includes a layer of thermoplastic film which is extruded over each side of the closed-weave woven base layer  12 , so that the closed-weave woven base layer  12  is sandwiched between the first and the second thermoplastic layers  22 A,  22 B. 
         [0065]    The slip resistant sheet material  10  for roofing is shown as having a thermoplastic layer  22 A or  22 B positioned over each side of the closed-weave woven base layer  12 . However, it is understood that certain applications may allow the closed-weave woven base layer  12  to have only one side coated with a thermoplastic layer. The thermoplastic layer(s) (such as first and second thermoplastic layers  22 A,  22 B) may include polyethylene, polypropylene, or other similar thermoplastic polymers. 
         [0066]    The slip resistant sheet material  10  for roofing is formed by extruding layers of thermoplastic polymer over the closed-weave woven base layer  12 . According to an embodiment, the first and the second thermoplastic layers  22 A,  22 B are directly affixed to the base layer without use of an adhesive or another intermediate layer. 
         [0067]    According to another embodiment, the thermoplastic layers may be affixed to the closed-weave woven base layer  12  using an adhesive or any other manner of attachment. 
         [0068]    The thermoplastic layers (i.e., such as first and second thermoplastic layers  22 A,  22 B) may be variably pigmented to allow the color of the thermoplastic layers to be selected based upon particular requirements. The thickness of the thermoplastic layers is selected such that the slip resistant sheet material  10  for roofing is flexible, whereby the flexible nature of the slip resistant sheet material  10  for roofing allows it to be formed into rolls and easily installed by simply unrolling the slip resistant sheet material  10  for roofing over a roof support structure or the like. 
         [0069]    The slip resistant sheet material for roofing  10  may be installed between a roof support structure  34  ( FIG. 6 ) and an overlayment  36  ( FIG. 7 ) in order to provide a waterproof barrier for the roof structure. The slip resistant sheet material  10  for roofing may be mechanically fastened to the roof rafters  38  ( FIG. 6 ) using nails or screws, but it is understood that the slip resistant sheet material  10  for roofing may be affixed to the roof rafters  38  using adhesives or other possible attachment methods. 
         [0070]    The slip-resistant sheet material  10  for roofing may be formed from a plurality of thermoplastic layers having an improved resistance to deterioration from exposure to external elements, such as moisture and dirt, so that the slip resistant sheet material  10  for roofing has an improved durability and longevity. Moreover, employing closed-weave woven base layer  12  including yarns of a second gauge  32  in the slip resistant sheet material  10  for roofing provides an improved tensile strength capable of being walked upon without tearing when being installed on the roof. The closed-weave woven base layer  12  further provides improved strength to resist tearing when exposed to external forces, such as collected moisture, wind, and other external forces. 
         [0071]    As shown, the improved resistance to deterioration and tearing provided by the slip resistant sheet material for roofing  10  improves the integrity and effectiveness of the weather-resistant barrier provided by the slip resistant sheet material for roofing  10 . By improving the longevity of the waterproof integrity of the slip resistant sheet material for roofing  10  to more closely match the integrity of the entire roof structure, the longevity of the integrity of the entire roof structure is improved. 
         [0072]    According to an embodiment, and referring now to  FIG. 6 , there is shown a perspective view of the slip resistant sheet material  10  for roofing being installed on an exemplary roof structure. The slip resistant sheet material  10  for roofing is to be installed between a roof support structure  34  and an overlayment  36  in order to provide a waterproof barrier and a slip resistant material for the roof structure. As shown, the slip resistant sheet material  10  for roofing may be formed into rolls  40  which can be simply unrolled over the roof support structure  34  to allow for easy installation. In this exemplary roof structure, the sarking method is utilized where the slip resistant sheet material  10  for roofing is fastened to the top side of the roof rafters  38  and allowed to drape between the open rafters bays  42 . The slip resistant sheet material  10  for roofing is preferably mechanically fastened to the roof rafters  38  using nails or screws, but it is understood that the slip resistant sheet material  10  for roofing may be affixed to the roof rafters  38  using another adhesives or other possible attachment methods. 
         [0073]    Battens  44  are then fastened over the slip resistant sheet material  10  for roofing and into the top side of the roof rafters  38 , where the overlayment  36  is then attached to the battens  44 , as shown in  FIG. 7 . The sarking method is merely one possible manner of installing a roof structure using the slip resistant sheet material  10  for roofing. For instance, the roof support structure  34  on which the slip resistant sheet material  10  for roofing is attached may include solid sheathing or spaced sheathing. Further, any type of batten structure may be attached to the slip resistant sheet material  10  for roofing for supporting the overlayment  36 , such as wood battens, steel battens, plastic battens, counter-battens made from any of these materials, or the overlayment  36  may be attached directly to the roof support structure  34  through the slip resistant sheet material  10  for roofing  10 . 
         [0074]    According to another embodiment and referring to  FIG. 5 , there is provided a method  100  for manufacturing a slip resistant sheet material  10  for roofing having an upper side and a lower side. 
         [0075]    The method  100  comprises providing a closed-weave woven base layer having a top surface facing in a same direction as the upper side (step  102 ). The method  100  further comprises affixing a first thermoplastic layer to the top surface (step  104 ). After affixing first thermoplastic layer to the top surface, the next step is embossing the base layer and the first thermoplastic layer to form projections in the same direction as the upper side at corresponding locations in the base layer and the first thermoplastic layer (step  106 ) thereby providing slip resistance on the upper side. 
         [0076]    According to an embodiment, the embossing (step  106 ) is performed at ambient temperature. 
         [0077]    According to an embodiment, the embossing (step  106 ) comprises embossing the base layer and the first thermoplastic layer with an engraved roller. 
         [0078]    According to an embodiment, the closed-weave woven base layer further comprises a bottom surface opposite the top surface and the method  100  further comprises affixing a second thermoplastic layer to the bottom surface (step  108 ). 
         [0079]    According to an embodiment, the affixing the first thermoplastic layer and the second thermoplastic layer (steps  104  and  108 ) comprises respectively directly affixing the first thermoplastic layer and the second thermoplastic layer to the top surface and to the bottom surface without use of an adhesive or another intermediate layer. 
         [0080]    According to an embodiment, the affixing the first thermoplastic layer and the second thermoplastic layer (steps  104  and  108 ) comprises respectively extruding a film-forming polymer (not shown) thereby producing the first thermoplastic layer and the second thermoplastic layer. 
         [0081]    According to an embodiment, further comprising respectively bonding the first thermoplastic layer and the second thermoplastic layer to the top surface and to the bottom surface (not shown). 
         [0082]    According to an embodiment, the extruding a film-forming polymer (step  110 ) comprises extruding at least one of: polyethylene and polypropylene. 
         [0083]    In accordance with another embodiment, there is provided a process  200  for manufacturing the slip resistant sheet material  10  for roofing. The process  200  for manufacturing the slip resistant sheet material  10  for roofing is shown in  FIG. 8 . First, the closed-weave woven base layer  12  is unwound into an unwinding machine for showing upwardly the top surface  14  of the closed-weave woven base layer  12 . Next, a polymer film  204  is extruded through a heated die  202  to form a first thermoplastic layer  22 A. The first thermoplastic layer  22 A bonds to the top surface  14  of the closed-weave woven base layer  12  at the nip point  206  where at least one of rollers  212 ,  214  is cooled for cooling the temperature of the closed-weave woven base layer  12  which is being bonded with the first thermoplastic layer  22 A. Optionally (not shown), the closed-weave woven base layer  12  is wounded and again unwound into the unwinding machine for showing upwardly the bottom surface  16  of the closed-weave woven base layer  12  . Another polymer film  204  is then extruded through the heated die  202  to form the second plastic layer  22 B covering the bottom surface  16  of the closed-weave woven base layer  12 . The second thermoplastic layer  22 B then bonds to the bottom surface  16  of the closed-weave woven base layer  12  at the nip point  206 , where at least one of rollers  212 ,  214  is cooled for cooling the temperature of the closed-weave woven base layer  12  which is being bonded with the second thermoplastic layer  22 B. Finally, at ambient temperature, the closed-weave woven base layer  12  that is now extruded with first and/or second thermoplastic layers  22 A,  22 B passes through an engraved roller  208  and a backer roller  210 . Using this process  200 , the embossed pattern  24  is respectively cast into the first thermoplastic layer  22 A, the closed-weave woven base layer  12  and alternatively, the second thermoplastic layer  22 B. Since the step of passing the closed-weave woven base layer  12  through the engraved roller  208  and the backer roller  210  is performed once the closed-weave woven base layer  12  is extruded with first and second thermoplastic layers  22 A,  22 B, there is no need for one or both roller(s)  212 ,  214  to be temperature controlled to cool the polymer film extrusion and engraved to provide the embossed pattern  24 . 
         [0084]    Alternatively, instead of passing between the engraved roller  208  engraved with bump patterns  216  and the backer roller  210 , the closed-weave woven base layer  12  that is extruded with or sandwiched between the first and/or second thermoplastic layers  22 A,  22 B, may pass under a press plate engraved with bump patterns (not shown). 
         [0085]    The engraved roller  208  is substantially cylindrical and includes a surface configured for embossing the slip resistant sheet material  10  to form the anti-skid surface. The surface of the engraved roller  208  includes a texture formed by a plurality of features that are raised and or sunken with respect to remainder of the surface of the engraved roller  208 . For example, the surface can include a plurality of protrusions from the surface of the engraved roller, a plurality of depressions in the surface of the engraved roller or both. The texture for forming the embossment on the closed-weave woven base layer  12  and on the thermoplastic layer(s)  22 A and/or  22 B may be of varying heights or depths or can be substantially the same height or depth. Example of heights and depths of the texture include between 0.01 mm to 10 mm. The texture can be disposed on the surface of the engraved roller  208  randomly or can be configured as a uniform or repeated pattern. Where the texture is disposed as an array of uniform or repeating configurations, examples may include straight lines, a cross-hatch pattern, a chevron pattern, a checked pattern, a company logo, dots, and the like. The texture can include raised and/or sunken features that are adjacent to each other or spaced apart from each other providing various densities. Examples include where the texture includes between 1 feature and 100 features per cm 2  of the surface of the engraved roller  208 . Additionally, the features of the texture can have the same shape or can have varying shapes such as square, triangular, circular, ovular, obround, rectangular, random, or any other suitable shape configured to form the anti-skid surface. 
         [0086]    Various additives may be included or applied to the slip resistant sheet material  10 . Examples may include various colorants, heat stabilizers, waterproofing treatments, strengthening laminates, antimicrobials, UV blockers and light stabilizers. The slip resistant sheet material  10  may also be printed with signage, such as logos, installation instructions, and/or orientation indicia. 
         [0087]    While preferred embodiments have been described above and illustrated in the accompanying drawings, it will be evident to those skilled in the art that modifications may be made without departing from this disclosure. Such modifications are considered as possible variants comprised in the scope of the disclosure.

Technology Category: b