SLIP RESISTANT SHEET MATERIAL FOR ROOFING AND METHOD OF MANUFACTURING THE SAME
(a) Field 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. (b) Related Prior Art 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. 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. 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. 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. According to an aspect, the projections are defined on the upper side and corresponding depressions are defined on the lower side. 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. 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. 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. 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. According to an aspect, at least one of the first thermoplastic layer and the second thermoplastic layer is vapor impermeable. According to an aspect, at least one the first thermoplastic layer and the second thermoplastic layer is a film-forming polymer. 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. 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. According to an aspect, the embossing is performed at ambient temperature. According to an aspect, the embossing comprises embossing the base layer and the first thermoplastic layer with an engraved roller. 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. 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. 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. 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. According to an aspect, the extruding a film-forming polymer comprises extruding at least one of: polyethylene and polypropylene. 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. The following terms are defined below. 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. 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. 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. 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. 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: It will be noted that throughout the appended drawings, like features are identified by like reference numerals. 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. Referring now to the drawings, and more particularly to 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. 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 As shown in 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 ( According to 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 22A, 22B. 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 22A, 22B. 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 cm2 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. 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. In accordance with an embodiment, the thermoplastic layer or the plurality of thermoplastic layers 22A, 22B may include a film-forming polymer. In accordance with an embodiment, the thermoplastic layer or the plurality of thermoplastic layers 22A, 22B comprise(s) polyethylene, polypropylene or a mixture of polyethylene and polypropylene. 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. The thermoplastic layers 22A, 22B (first thermoplastic layer 22A and second thermoplastic layer 22B) 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 Now referring to 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. Still referring to 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. 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. 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. The yarns of the first direction 18 and the yarns of the second direction 20 are interwoven as shown in 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 Referring to The slip resistant sheet material 10 for roofing is shown as having a thermoplastic layer 22A or 22B 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 22A, 22B) may include polyethylene, polypropylene, or other similar thermoplastic polymers. 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 22A, 22B are directly affixed to the base layer without use of an adhesive or another intermediate layer. 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. The thermoplastic layers (i.e., such as first and second thermoplastic layers 22A, 22B) 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. The slip resistant sheet material for roofing 10 may be installed between a roof support structure 34 ( 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. 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. According to an embodiment, and referring now to 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 According to another embodiment and referring to 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. According to an embodiment, the embossing (step 106) is performed at ambient temperature. According to an embodiment, the embossing (step 106) comprises embossing the base layer and the first thermoplastic layer with an engraved roller. 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). 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. 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. 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). According to an embodiment, the extruding a film-forming polymer (step 110) comprises extruding at least one of: polyethylene and polypropylene. 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 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 22A, 22B, may pass under a press plate engraved with bump patterns (not shown). 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) 22A and/or 22B 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 cm2 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. 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. 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. The present document describes 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. The base layer and the thermoplastic layer define projections and corresponding depressions transversely to the thickness of the slip resistance material whereby, when the worker walks 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. 1. A slip resistant sheet material for roofing having an upper side and a lower side, the slip resistant sheet material comprising:
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. 2. The slip resistant sheet material of 3. The slip resistant sheet material of 4. The slip resistant sheet material of 5. The slip resistant sheet material of 6. The slip resistant sheet material of 7. The slip resistant sheet material of 8. The slip resistant sheet material of 9. The slip resistant sheet material of 10. A method for manufacturing a slip resistant sheet material for roofing having an upper side and a lower side, the method comprising:
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. 11. The method of 12. The method of 13. The method of 14. The method of 15. The method of 16. The method of 17. The method of 18. 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 comprising:
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.BACKGROUND
SUMMARY
BRIEF DESCRIPTION OF THE DRAWINGS
DETAILED DESCRIPTION