Impact Resistant Sheet Material

Abstract

The present invention provides an impact resistant sheet material that helps provide exterior walls of a building with resistance to impacts so that the building structure can meet building standards, such as the Miami-Dade County Large Missile Impact Test, for resisting impacts in high wind areas. In one embodiment, sheet material comprises an impact resistant layer that attached to fibrous substrate. The impact resistant layer provides impact resistance to the sheet material so that a wall structure employing the sheet material is able to successfully withstand an impact from a projectile comprising a 9 pound, 7 foot two-by-four (“2×4”) traveling at a speed of at least 34 miles per hour. The impact resistant sheet material may comprise a moisture vapor permeable, water-impermeable barrier layer having a hydrohead of at least 55 cm and a moisture vapor transmission rate of at least 35 g/m 2 /day. Such a sheet material is particularly useful in barrier applications, such as a house wrap.

1 . An impact resistant sheet material comprising:
 a moisture vapor permeable, water-impermeable, polymeric barrier layer having a hydrohead of at least 55 cm and a moisture vapor transmission rate of at least 35 g/m 2 /day; and   an impact resistant layer attached to the barrier layer, the impact resistant layer comprising a fabric layer having at least two pluralities of strands that extend in different directions and intersect each other, the impact resistant layer having a tensile strength of at least 445 Newtons, an elongation that is between 2 and 20 percent, and an Impact Resistance as measured by the Free-Falling Dart Method of greater than about 0.7 pounds.   
     
     
         2 . The impact resistant sheet material of  claim 1 , wherein the impact resistant layer has an elongation that is between 5 and 15%. 
     
     
         3 . The impact resistant sheet material of  claim 1 , wherein the impact resistant layer has an elongation that is between 5 and 12%. 
     
     
         4 . The impact resistant sheet material of  claim 1 , wherein the barrier layer comprises a nonwoven or woven material. 
     
     
         5 . The impact resistant sheet material of  claim 1 , wherein the barrier layer comprises a nonwoven substrate comprising polymeric fibers randomly disposed and bonded to one another, and a breathable polymeric film layer overlying one surface of the nonwoven substrate and intimately bonded thereto. 
     
     
         6 . The impact resistant composite sheet material of  claim 5 , wherein the film layer comprises an extrusion coated polyolefin, and the nonwoven substrate comprises substantially continuous spunbond polypropylene filaments. 
     
     
         7 . The impact resistant sheet material of  claim 1 , wherein the barrier layer comprises a fibrous substrate having a surface to which a breathable monolithic polymeric film layer is adhered thereto. 
     
     
         8 . The impact resistant sheet material of  claim 7 , wherein the fibrous substrate is selected from the group consisting of spunbond webs, woven slit films, carded webs, meltblown webs, flashspun webs, woven, and extruded webs. 
     
     
         9 . The impact resistant sheet material of  claim 1 , wherein the sheet material has a Mullen burst strength of at least 175 pounds and an Impact Resistance as measured by the Free-Falling Dart Method of greater than about 1 pound. 
     
     
         10 . The impact resistant sheet material of  claim 9 , wherein the sheet material has an Impact Resistance as measured by the Free-Falling Dart Method of greater than 2 pounds. 
     
     
         11 . The impact resistant sheet material of  claim 1 , wherein the impact resistant layer includes a first plurality of strands that extend in a first direction, a second plurality of strands that extend in a second direction that is different than the first direction, and third and fourth pluralities of strands that both extend at an angle with respect to the first plurality of strands and are oriented at opposite angles with respect to each other so they intersect each other in an X-like pattern. 
     
     
         12 . An impact resistant sheet material comprising a moisture vapor permeable, water impermeable composite sheet material having barrier properties making it suitable for use as a housewrap, the sheet material comprising:
 a fibrous substrate;   a breathable polymeric film layer overlying one surface of the substrate and intimately bonded thereto, the film layer having a moisture vapor transmission rate (MVTR) of at least 35 g/m 2 /day at 50% relative humidity and 23° C. and a hydrostatic head of at least 55 cm; and   an impact resistant layer attached to a surface of the substrate opposite the film layer, the impact resistant layer comprising a fabric having at least two pluralities of intersecting strands that extend in different directions with respect to each other, wherein the impact resistant layer has a tensile strength of at least 445 Newtons and an elongation that is less than 20 percent and an Impact Resistance as measured by the Free-Falling Dart Method of greater than about 2 pounds.   
     
     
         13 . The impact resistant sheet material of  claim 12 , wherein the impact resistant layer has an elongation that is between about 6 and 10%. 
     
     
         14 . The impact resistant sheet material of  claim 12 , wherein the impact resistant layer has a tensile strength that is from about 600 to 1200 N. 
     
     
         15 . A method of constructing an impact resistant wall structure comprising fastening an exterior surface of a sheathing material mounted on an exterior side of the wall structure with an impact resistant sheet material, the impact resistant sheet material comprising a moisture vapor permeable, water-impermeable polymeric barrier layer having a hydrohead of at least 55 cm and a moisture vapor transmission rate of at least 35 g/m 2 /day; and an impact resistant layer attached to the barrier layer, the impact resistant layer comprising a fabric layer having at least two pluralities of strands that extend in different directions and intersect each other, the impact resistant layer having a tensile strength of at least 445 Newtons, an elongation that is between 2 and 20 percent, and wherein the wall structure is able to successfully withstand an impact from a projectile comprising a 9 pound, 7 foot two-by-four traveling at a speed of at least 34 miles per hour without penetration of the wall structure. 
     
     
         16 . The method of  claim 15 , wherein the impact resistant layer has an elongation that is between 5 and 15%. 
     
     
         17 . The method of  claim 15 , wherein the impact resistant layer has an elongation that is between about 6 and 10%. 
     
     
         18 . The method of  claim 15 , wherein the wall structure is capable of passing the Large Missile Impact Resistance Test according to TAS 201-94, and the Cyclic Wind Pressure Loading Test according to TAS 203-94. 
     
     
         19 . The method of  claim 15 , the barrier layer comprises a fibrous substrate having a surface to which a breathable polymeric film layer is adhered thereto. 
     
     
         20 . The method of  claim 19 , wherein the fibrous substrate is selected from the group consisting of spunbond webs, woven slit films, carded webs, meltblown webs, flashspun webs, woven, and extruded webs.