Abstract:
A polymer-based composite structural board for in-ground and above-ground use without material degradation has a polymer material or predominantly polymer material core layer with a density between 1.6 lbs/ft 3  and 25 lbs/ft 3 . A facer overlays, is generally coextensive with, and is bonded to at least one of the major surfaces and preferably both of the major surfaces of the core layer. The facer(s) enhance the integrity and fastener pull through strength of the polymer-based composite structural board as well as other desired physical and performance characteristics of the polymer based composite structural board. The polymer-based composite board is used in foundation wall systems, utility conduit systems and other systems where the composite board is in ground contact.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject invention relates to polymer-based composite structural boards that can withstand long term contact with the ground while in service without material degradation and to building foundation and other systems that include the polymer-based composite structural boards. 
         [0002]    For in-ground, below grade, applications where the polymer-based composite structural boards of the subject invention will be in long term contact with soil, gravel and/or other fill, the polymer-based composite structural boards of the subject invention, when compared to plywood boards, hardboards, particleboards, etc., should be able to provide advantages in installation and/or in service performance. The polymer-based composite structural boards of the subject invention can be relatively light in weight, easy to handle, and easily cut at the job site, e.g. to form a sheathing layer or a utility conduit. In addition, the polymer-based composite structural boards of the subject invention are strong and durable, absorb and retain very little moisture, are fungus growth resistant, are flame spread resistant, have relatively good thermal and acoustical properties, and have good bonding surfaces for bonding a nonstructural finish layer to a sheathing or other layer formed by the polymer-based composite structural boards. 
       SUMMARY OF THE INVENTION 
       [0003]    The polymer-based composite structural boards of the subject invention have a polymer material or predominantly polymer material core layer with a density between 1.6 lbs/ft 3  and 25 lbs/ft 3 . The polymer-based composite structural boards of the subject invention are intended for use where the structural boards will be in long term ground contact during service, such as but not limited to exterior foundation wall sheathing and utility conduits. A facer overlays at least one of the major surfaces and preferably, facers overlay both of the major surfaces of the core layers of the polymer-based composite structural boards of the subject invention. A facer of a polymer-based composite structural board of the subject invention is generally coextensive with and bonded to the overlaid major surface of the polymer-based composite structural board and enhances the integrity and fastener pull through strength of the polymer-based composite structural sheathing board as well as other desired physical and performance characteristics of the polymer based composite structural board. In particular, the polyisocyanurate material or predominantly polyisocyanurate material polymer-based composite structural boards of the subject invention have good dimensional stability, can be relatively light in weight (especially when facers overlay both major surfaces), are easy to handle, and can be easily cut at the job site to form a foundation sheathing layer, in-ground utility conduit, etc. In addition, these polyisocyanurate material or predominantly polyisocyanurate material polymer-based composite structural boards exhibit good thermal and acoustical properties, are strong and durable, absorb and retain very little moisture, are fungus growth resistant, are flame spread resistant, and have good bonding surfaces for bonding a nonstructural finish-wall layer (e.g. paint on an interior foundation basement wall) to a wall sheathing layer formed by the polymer-based composite structural boards. With their excellent physical properties and characteristics, the polymer-based polyisocyanurate material or predominantly polyisocyanurate material composite structural boards of the subject invention are well suited for many building construction applications where the composite structural boards will be in long term below grade contact with the ground. In addition to in-ground, below grade applications, these polymer-based composite structural boards can also be utilized for above ground applications. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a schematic transverse cross section in elevation of a concrete foundation wall system that is partially below grade (partially below ground level) and includes the polymer-based composite structural boards of the subject invention in the wall system. 
           [0005]      FIG. 2  is a schematic transverse cross section in elevation of a utility conduit system, which contains water lines and/or other utilities, wherein the utility conduit of the system is made wholly or in part of the polymer-based composite structural boards of the subject invention. 
           [0006]      FIG. 3  is a fragmentary schematic perspective view of a first embodiment of the polymer-based composite structural board of the subject invention with portions broken away to better show the layers of composite. 
           [0007]      FIG. 4  is a fragmentary schematic perspective view of a second embodiment of the polymer-based composite structural board of the subject invention with portions broken away to better show the layers of composite. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0008]    As schematically shown in  FIG. 1 , a foundation system  20  of the subject invention includes a concrete foundation wall  22  extending upward from a concrete slab or floor  24 . The concrete foundation wall  22  is partially below and partially above ground level  18  and contained between interior and exterior form and sheathing layers  26 . The interior and exterior form and sheathing layers  26  are constructed from a plurality the polymer-based composite structural boards  40  or  42  of  FIGS. 3 and 4 . As shown, the interior and exterior sheathing layers  26  of the foundation system  20  can serve the dual function of providing a form for making the concrete foundation wall  22  and of providing interior and exterior sheathing layers that enhance the performance of the concrete foundation wall  22  in service, e.g. by thermally insulating the wall, by providing fungus growth resistant sheathing layers, and providing a flat, uniform, good bonding surface on the interior of the wall for the application of a finish layer. Where desired, the sheathing layers  26  or portions of the sheathing layers  26  can be removed after the concrete of the foundation wall  22  sets and cures and before the excavation for the foundation system  20  is refilled with a desired fill, e.g. top soil, dirt, gravel, etc. 
         [0009]    As schematically shown in  FIG. 2 , a utility conduit system  30  of the subject invention includes a utility conduit section  32 , constructed of the polymer-based composite structural boards  40  or  42  of  FIGS. 3 and 4 , and utilities such as a water line  34  and/or other utilities for servicing a home, apartment complex, business, etc. that are contained within the utility conduit  32 . As shown, a utility conduit section  32 , which is rectangular in transverse cross section, preferably has a removable cover  36  that is constructed from a polymer-based composite structural board  40  or  42  and side and bottom walls  38  that are secured together by conventional mechanical fasteners and/or adhesives (not shown) and constructed from polymer-based composite structural boards  40  or  42 . The utility conduit system  30  can include only one utility conduit section  32  or, depending on the length of the utility conduit system  30 , a series of the utility conduit sections  32  that are joined together in end to end relationship by conventional mechanical fasteners and/or adhesives (not shown) to form the utility conduit system  30 . Preferably, the removable cover  36  forms a shiplap or other joint with the sidewalls  38  of the utility conduit section to close, insulate, and seal off the interior of the utility conduit section  32  from external conditions while in service. Where the utility conduit system  30  is formed of a plurality of the utility conduit sections  32 , some of the utility conduit sections may have a removable cover  36  while other of the utility conduit sections  32  have covers that are permanently secured to the sidewalls  38  of the utility conduit sections  32 . As shown, the cover  36  of the utility conduit section  32  is at ground level  18 . However, the utility conduit section  32  could be completely below ground level  18  (below grade) and totally covered fill, e.g. soil, dirt, gravel, etc. or partially above and partially below ground level  18 . The utility conduit sections  32 , thermally insulate the utilities within the conduit from external conditions, keep the utilities housed within the conduit sections dry, are durable, and are fungus growth resistant. 
         [0010]    The polymer-based composite structural board  40  of  FIG. 3  includes a polymer material or predominantly polymer material core layer  52  and a facer  54  coextensive with or substantially coextensive with and bonded to a first major surface of the core layer  52 . The polymer-based composite structural board  42  of  FIG. 4  includes a polymer material or predominantly polymer material core layer  52 ; a first facer  54  coextensive with or substantially coextensive with and bonded to a first major surface of the core layer  52 ; and a second facer  56  coextensive with or substantially coextensive with and bonded to a second major surface of the core layer  52 . 
         [0011]    The first major surface and the second major surface of the polymer or predominantly polymer material core layer  52  of the polymer-based composite structural boards  40  and  42  are each defined by the length and the width of the polymer or predominantly polymer material core layer. The polymer or predominantly polymer material core layer  52  typically has a width of about four feet or greater and a length of about four feet or greater and, preferably, a length of about eight feet. 
         [0012]    The polymer or predominantly polymer material core layer  52  of the polymer-based composite structural boards  40  and  42  may be made of various polymer or predominantly polymer materials [e.g. a polyisocyanurate, polyurethane, polystyrene, or phenolic material or a material made of a blend of these materials; a polyisocyanurate, polyurethane, polystyrene, or phenolic foam material or a foam material made of a blend of these materials; a predominantly polyisocyanurate, polyurethane, polystyrene, or phenolic material with up to 40% by weight, but typically between about 1% and about 25% by weight organic and/or inorganic filler(s) or a material made of a blend of these materials with up to 40% by weight, but typically between about 1% and about 25% by weight organic and/or inorganic filler(s); a predominantly polyisocyanurate, polyurethane, polystyrene, or phenolic foam material with up to 40% by weight, but typically between about 1% and about 25% by weight organic and/or inorganic filler(s) or a foam material made of a blend of these materials with up to 40% by weight, but typically between about 1% and about 25% by weight organic and/or inorganic filler(s), a material made of other thermoset matrix polymers; etc.]. However, a preferred material for the core layer  52  is a polyisocyanurate material or foam material or a predominantly polyisocyanurate material or foam material with up to 40% by weight, but typically between about 1% and about 25% by weight organic and/or inorganic filler(s). Examples of various fillers that may be used in the predominantly polymer materials of the core layer  52  include but are not limited to powdered, liquid, and fiber fillers. The polymer or predominantly polymer materials of the core layer  52  may also include fiber reinforcements, fungi growth-inhibiting agents, fire-retardants, and other agents to reduce the cost of and/or modify the properties of the core layer  52 , such as but not limited to the compressive strength, the toughness, the flexibility, the friability, and the fire resistance of the core layer. Examples of fillers, which may be used in the predominantly polymer material core layer  52 , are fillers such as but not limited to limestone (CaCO 3 ), fiberglass, recycled polyisocyanurate dust, extenders/plasticizers, ground up foam insulation, ground up rubber, wood dust, etc. 
         [0013]    The first facer  54  of the polymer-based composite structural board  40  and the first and second facers  54  and  56  of the polymer-based composite structural board  42  typically overlie the entire or substantially the entire major surface of the core layer  52  of the polymer-based composite structural board  40  or  42  to which the facer is or facers are bonded. The facers  54  and  56  of the polymer-based composite structural boards  40  and  42  may be any sheet material that provides suitable first and/or second major surfaces for the polymer-based composite structural boards  40  and  42 , such as but not limited to coated or uncoated paper, foil, coated or uncoated woven or nonwoven mats made of fiberglass and/or other fibers or filaments, coated or uncoated scrims made of fiberglass and/or other fibers or filaments, etc. However, a preferred facer material for the facers  54  and  56  is an alkali resistant facer material such as but not limited to a mineral coated nonwoven fiberglass mat or fiberglass scrim wherein the coating protects the fiberglass mat or scrim from alkali degradation. Where a coated or uncoated fiberglass scrim material is used, preferably, the scrim material has a tensile strength of at least 105 lbs per linear inch, a weight of about 10 grams/ft 2 , 8×8 strands per inch, and utilizes stands having a mean diameter of about 0.019 inches. 
         [0014]    The polymer-based composite structural boards of the subject invention preferably have the following physical properties: 
         [0000]    
       
         
               
               
               
             
               
               
             
           
               
                   
               
               
                   
                   
                 Preferred Range 
               
               
                 Property 
                 Range or Minimum 
                 or Minimum 
               
               
                   
               
             
             
               
                 Thickness 
                 0.15 to 2.5 inches 
                 0.25 to 2.0 inches 
               
               
                 Density 
                 1.6 to 25 lbs/ft 3   
                 3 to 10 lbs/ft 3   
               
               
                 Compressive Strength 
                 at least 25 psi 
                 at least 50 psi 
               
               
                 Flexural Strength 
               
               
                 Modulus of Rigidity 
                 at least 400 psi 
                 at least 1500 psi 
               
               
                 (MOR) 
               
               
                 Load at Yield 
                 at least 20 lbf 
                 at least 30 lbf 
               
               
                 Fastener Pull Through 
                 at least 20 lbf 
                 at least 50 lbf 
               
               
                 (ASTM Test D1037 - in 
               
               
                 effect - June 2006) 
               
               
                 Water Absorption by Volume 
                 4% or less 
                 2% or less 
               
               
                 (ASTM Test C209 - in 
               
               
                 effect - June 2006) 
               
               
                 Thermal Conductivity 
                 R-value of at least 1 
               
               
                 Flame Spread Rating 
                 at least 20 
                 at least 25 
               
               
                 (ASTM Test E84 - in 
               
               
                 effect - June 2006) 
               
             
          
           
               
                 Fungus Growth Resistance 
                 Does Not Support Fungus Growth 
               
               
                   
               
             
          
         
       
     
         [0015]    In describing the invention, certain embodiments have been used to illustrate the invention and the practices thereof. However, the invention is not limited to these specific embodiments as other embodiments and modifications within the spirit of the invention will readily occur to those skilled in the art on reading this specification. Thus, the invention is not intended to be limited to the specific embodiments disclosed, but is to be limited only by the claims appended hereto.