Abstract:
Implementations of the present disclosure provide an environmentally resistant structural member for use in areas exposed to water or other environmental elements. The structural member includes a core member and a polymer layer. The core member has an environmentally sensitive composition wherein extended exposure to the environmental element causes degradation of the core member. The core member includes at least one surface, such as a bottom and side surfaces. The surface is configured for positioning in the area exposed to the environmental element. The polymer layer has a molded shape and covers the surface so as to seal the surface of the core member against exposure to the environmental element.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present invention claims the benefit of U.S. Provisional Patent Application No. 61/660,993 filed Jun. 18, 2012, and is herein incorporated in its entirety by reference. 
     
    
     BACKGROUND 
       [0002]    A typical exterior doorframe is made from wood. For any frames that will be primed, the wood is typically made from pine due to lower costs. Non-primed, natural frames are made from the species required for their natural stained finish like Oak, Maple, Cherry or Pine. 
         [0003]    The problem with wood frames, especially primed frames, is they are subject to rot and defection from the weather and termite elements. In many incidences the frames are rotted on the bottom due to the water wicking up from the unprotected bottom. Wood frame bottoms may also be subject to rot from termites. The rest of the frame is also subject to defects due to weather. Because wood is fiber based, the harshness of the weather can cause decay, deformation, and other defects. 
         [0004]    Improvements to wood frames to fight moisture, rot and decay are therefore desired. 
       SUMMARY 
       [0005]    Implementations of the present disclosure overcome the problems of the prior art by providing an environmentally resistant structural member for use in areas exposed to water or other environmental elements. The structural member includes a core member and a polymer layer. The core member has an environmentally sensitive composition wherein extended exposure to the environmental element causes degradation of the core member. The core member includes at least one surface. The surface is configured for positioning in the area exposed to the environmental element. The polymer layer has a molded shape and covers the surface so as to seal the surface of the core member against exposure to the environmental element. 
         [0006]    The core member may have a water permeable surface. For example, the core member may have a plurality of fibers, such as cellulose fibers. The core member may be a wood member, such as a low cost pine wood member. 
         [0007]    Included in the molded shape of the core member may be a molded surface texture. For example, a wood grain pattern may be molded on the molded shape. Wood grain patterns may include oak, maple, cherry or pine. 
         [0008]    The structural member may be configured for external use on a building. For example, it may be used as a frame member, such as a door or window frame member. 
         [0009]    The polymer layer may be molded about an entire external surface of the core member. The polymer layer may have a thickness of ⅝ inch or less. For example, the polymer layer may be 3/16 of an inch. The polymer layer may include a polyurethane. 
         [0010]    A method of molding the structural member includes placing a core member in a mould cavity. The mould cavity defines an external shape. The method includes placing one or more polymer components in the mould cavity. The mould cavity is sealed. The method also includes foaming the polymer components to encapsulate at least a portion of the core member. This generates an external layer of the structural member that is resistant to water permeation. 
         [0011]    Foaming may include encapsulating the entire core member. Foaming the polymer components may also include combining at least two polyurethane components. 
         [0012]    The core member may have a permeable surface. Foaming may include penetrating the permeable surface of the core member. For example, foaming the polymer components may include penetrating the fibers of the core member. 
         [0013]    The method may also include forming a surface texture on the external layer. 
         [0014]    Also, the method may include sizing the core member to have a gap between the edges of the mold and the core member of ⅝ inch or less. 
         [0015]    The method may also include curing the external layer. 
         [0016]    These and other features and advantages of the implementations of the present disclosure will become more readily apparent to those skilled in the art upon consideration of the following detailed description and accompanying drawings, which describe both the preferred and alternative implementations of the present disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a bottom view of an environmentally resistant structural member implemented as a door jamb; 
           [0018]      FIG. 2  is a plan view of the door jamb of  FIG. 1 ; 
           [0019]      FIG. 3  is a cross-sectional view of the door jamb of  FIG. 1 ; 
           [0020]      FIG. 4  is a cross-sectional view of the door jamb of  FIG. 1 ; 
           [0021]      FIG. 5  is a perspective view of the door jamb of  FIG. 1 ; and 
           [0022]      FIG. 6  is a perspective view of removal of an environmentally resistant crown molding structure being removed from a mold. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Implementations of the present disclosure now will be described more fully hereinafter. Indeed, these implementations can be embodied in many different forms and should not be construed as limited to the implementations set forth herein; rather, these implementations are provided so that this disclosure will satisfy applicable legal requirements. As used in the specification, and in the appended claims, the singular forms “a”, “an”, “the”, include plural referents unless the context clearly dictates otherwise. The term “comprising” and variations thereof as used herein is used synonymously with the term “including” and variations thereof and are open, non-limiting terms. 
         [0024]    Implementations of the present disclosure provide an environmentally resistant structural member. The structural member includes a core member and a polymer layer. The polymer layer is molded onto the core member on at least one surface, such as around its bottom and/or side surfaces. The polymer layer advantageously protects against water and other environmental elements (e.g., sun, wind, dirt, dust, temperature, etc.) and improves rigidity of the structural member. Also, the structural member advantageously is composed of relatively low cost materials. Further, the structural member can be produced to have the appearance of various wood species. 
         [0025]    An environmentally resistant structural member in the form of a door jamb  10  is shown in  FIGS. 1-5 . The door jamb includes a core member  12  and a polymer layer  14 , as shown, for example, in  FIG. 4 . The polymer layer  14  is molded onto the core member  12  at least around its bottom and/or side surfaces. The polymer layer  14  advantageously protects against water and other environmental exposure and improves rigidity of the door jamb  10 . Also, the structural member advantageously is composed of relatively low cost materials. Further, the structural member can be produced to have the appearance of various wood species. 
         [0026]    Although a door jamb is one implementation and has particular advantages, other implementations of a polymer coated core member are also possible including various structural members for residential and commercial construction. Instead of a door jamb, the structural member may be a cornice, siding, window sashes and frames, garage doors, etc.  FIG. 6 , for example, shows a polymer coated core member used for crown molding. 
         [0027]    The core member  12  may have a water permeable surface. For example, the core member  12  may be a low cost wood substrate, such as pine, which has a fibrous composition (e.g., cellulose) that is prone to wicking up water. Advantageously, the use of the core member  12  can provide structural stability and is less expensive than an entirely polymeric structural member. 
         [0028]    The polymer layer  14  may, for example, include or be formed by a polyurethane foam. The polymer layer  14  may be molded to form all of the external surfaces of the door jamb  10 . The polymer layer may be molded to have a surface texture, as defined by negative or positive (raised) areas in the mold. For example, the surface texture could be a pebble texture or a wood grain to mimic known and desirable wood types, such as oak, maple, pine or cherry. 
         [0029]    Preferably, the structural member is shaped to be used on an external surface of a structure. For example, as shown in  FIG. 5 , the door jamb  10  includes a base  22  and a raised portion  24 . The base  22  is configured for attachment within or to underlying support structure of an edifice, building, residential home or other structure. The raised portion  24  is configured to abut front surfaces of the door to inhibit swinging of the door in the wrong direction. Both the base  22  and raised portion  24  can work with the door to seal the door opening and prevent intrusion of weather and/or loss of heating and cooling. 
         [0030]    The base  22  may include a pair of long sides  16 , a top side  18 , a bottom side  20 , a front surface  26  and a back surface  28 . The long sides  16  are generally parallel and the top and bottom sides,  18  and  20 , are also generally parallel. Together, the sides form a rectangular shape that can be aligned with and affixed to a standard building structural member, such as a 2×4 frame in a stick-built residential home. The front surface  26  will usually be visible and thus bear some type of a molded finish. 
         [0031]    The thickness of the base  22  may be tailored to the size and penetrating capacity of conventional nails and fasteners. For example, the base may be 0.75 inch thick. Other dimensions, such as the length of the various sides can be similarly tailored to the anticipated use. For example, the jamb width (e.g., the length of the top and bottom sides  18 ,  20 ) may be 4- 9/16 inches. The length of the long sides  16  may be tailored for standard door heights, such as 7, 7.5 or 8 foot door heights. 
         [0032]    Edges of the door jamb  10  may be right-angles or have chamfers, rounds, or other modifications for an attractive appearance or improved function. 
         [0033]    The raised portion  24  extends away from the front surface  26  of the base  22  about 0.5 inch, as shown in  FIGS. 1 ,  2  and  5 . (It should be noted that the dimensions used herein, although particularly advantageous for particular applications and implementations, should not be interpreted to further limit the claimed invention.) The raised portion  24  includes a pair of long sides  30 , a top side  32 , a bottom side  34  and a front surface  36 . One of the long sides  30  is an extension of the subjacent long side  16  of the base  22 , as shown in  FIG. 1 . The other one of the long sides  30  is a step up from the front surface  26  of the base  22 . The stepped up long side  30  and adjacent front surface  36  are configured to abut and seal (or support a seal) against a closed door. 
         [0034]    The top edge or side  32  of the raised portion  24  is parallel to, but inset from, the top side  18  of the base  22 . This allows the remaining portion of the base  22  to extend under an abutting top doorframe member. 
         [0035]    The bottom side  34  of the base  22  is angled slightly with respect to, and inset in from, the bottom side  20  of the base  22 . This provides space to accommodate a threshold tread which often has an angled upper surface. 
         [0036]      FIG. 3  shows the core member  12  which reflects a nearly congruent shape to the overall door jamb  10 . The core member  12  includes a core base  38  supporting a core raised portion  40 . The core base  38  may be a distinct wood piece that has a pair of opposing long sides  42 , a top side  44  and a bottom side  46 , as shown in  FIG. 3 . The core base  38  has a thickness of about 0.374 inch and a width of about 4.186 inch. 
         [0037]    As shown in  FIG. 4 , the core raised portion  40  also includes a pair of long sides  50 , a top side  52 , a bottom side  54  and a front surface  56 . The core raised portion  40  may be a separate wood (or other fibrous or inexpensive material) piece that is attached to the top surface  44  of the core base  38 . The core raised portion  40  for example, may be a 1.561 inch width by 0.188 inch thickness wood piece attached with one of its long sides  50  above and coplanar with the subjacent long side  42  of the core base  38 , as shown in the cross-section of  FIG. 5 . Alternatively, the core base  38  and raised portion  40  may be a unitary piece, such as one milled from a solid, rectangular cross-section. 
         [0038]    As shown in  FIG. 4 , the top and bottom sides  52 ,  54  of the core raised portion are inset from the top and bottom sides  44 ,  46  of the core base  38 , similar to the outward geometry of the jamb  10 . The core raised portion  40  is varied in length to suit the varied length of the core base  38  and the overall door jamb  10  length. 
         [0039]    The polymer layer  14 , as mentioned above, may be a molded layer that extends around the outer surfaces of the core member  12 . Cross-sectional  FIGS. 3 and 4  show the enveloping configuration of the polymer layer  14 . Generally, the polymer layer  14  may be advantageously 3/16 inch to ⅝ inch thick for external structural member construction to balance rigidity, strength and durability with respect to moisture and other elements. Polyurethanes have the characteristics of being injection moldable and the ability to form a relatively dense coating that lends structural rigidity as well as environmental resistance. Other moldable polymers, however, may also be employed for coating the core member. Thermosetting and thermoplastics may, for example, be employed such as epoxy, phenolic, nylon, polyethylene or polystyrene. Generally, injection molding is capable of tolerances equivalent to an international tolerance grade of about 9-14. The possible tolerance of a thermoplastic or a thermoset may be ±0.008 to ±0.002 inches. Surface finishes of two to four microinches or better can be obtained. 
         [0040]    The molding process includes placing the core member  12  in a mould with the final profile of the finished product, such as the door jamb  10 . Polyurethane is poured into the mould. The polyurethane may include a two part liquid that foams upon mixing within the mold. Multiple components need not be used and instead a single-component foaming polymer may be used, such as an epoxy that foams when exposed to air. 
         [0041]    The mould is shut tight with presses to apply pressure and keep the mould shut tightly while the polyurethane is foaming up. After certain amount of time calibrated to the foam composition, thickness and other parameters, the urethane foam will cure and become harden to the profile of the mould. At this time the press can be released and the mould be opened to pull the part out. 
         [0042]    Out of the mould, the part will have the hard, cured polyurethane layer  14  encapsulating the inner wood core member  12 . Depending on the density of the polyurethane used, the cured polyurethane around the wood core member  12  can be as soft as cotton or as hard as wood or stone. The density is controlled to meet the requirement of the product application. This final product is protected against the elements of weather, termites, water, salt, etc. 
         [0043]    Another advantage of the molding process is the ability to form a predetermined kind of wood profile on the surface. Oak, Cherry, Pine, Maple or Mahogany or any other texture may be formed on the surface because the urethane is initially in liquid form and will expand to fill any detail profile of the mould. 
         [0044]    The polyurethane layer  14  can also be primed, stained, cut, shaped, sanded and worked on just like wood. Thus, the door jamb  10  or other structural member can replicate wood but have all the benefit features of maintenance free properties of polyurethane against the elements. 
         [0045]    A number of aspects of the systems, devices and methods have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other aspects are within the scope of the following claims. 
       REFERENCE NUMBERS 
       [0046]      10  door jamb 
         [0047]      12  core member 
         [0048]      14  polyurethane layer 
         [0049]      16  long sides 
         [0050]      18  top side 
         [0051]      20  bottom side 
         [0052]      22  base 
         [0053]      24  raised portion 
         [0054]      26  front surface 
         [0055]      28  back surface 
         [0056]      30  long sides 
         [0057]      32  top side 
         [0058]      34  bottom side 
         [0059]      36  front surface 
         [0060]      38  core base 
         [0061]      40  core raised portion 
         [0062]      42  long sides 
         [0063]      44  top side 
         [0064]      46  bottom side 
         [0065]      50  long sides 
         [0066]      52  top side 
         [0067]      54  bottom side 
         [0068]      56  front surface