Patent Publication Number: US-10315386-B2

Title: Gypsum composites used in fire resistant building components

Description:
PRIORITY CLAIM AND CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a continuation application of U.S. patent application Ser. No. 13/603,405 filed on Sep. 4, 2012 and entitled “Gypsum Composites Used in Fire Resistant Building Components”, which is a continuation-in-part application of: (1) U.S. patent application Ser. No. 13/538,788 filed on Jun. 29, 2012 and entitled “Fire Rated Door Core”; and (2) U.S. patent application Ser. No. 13/538,828 filed on Jun. 29, 2012, now U.S. Pat. No. 9,243,444, and entitled “Fire Rated Door”. All these applications are hereby incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to the field of composite materials and, more particularly, to gypsum composites used in fire resistant building materials. 
     BACKGROUND OF THE INVENTION 
     Many methods and techniques for manufacturing fire rated doors have been developed over time. But most of these prior art designs do not lend themselves well to fully automated manufacturing processes. Moreover, the prior art fire rated doors are expensive and require the internal mineral core. The internal core can be exposed in routed details and may reduce the strength of the door as a result of the reduced thickness of the door panels. In addition, alignment of the panels during assembly can be troublesome and require additional finishing to square the door after assembly. 
     Cement-based composites have been used in building materials for many years. For example, U.S. Pat. Nos. 5,549,859, 5,618,341, 5,631,097, 5,641,584, 5,658,624, 5,702,787, 5,766,525, 5,798,151, 5,849,155 and 6,379,446, and U.S. Published Patent Applications 2008/0099122, 2010/0136269 and 2011/0120349 describe various compositions and processes for making extruded cement-based composite products, all of which are hereby incorporated by reference in their entirety. These patents and published patent applications, however, do not disclose fire resistant composite components having the necessary fire resistant capabilities to produce doors, door cores and building panels that can receive fire rated certifications. 
     SUMMARY OF THE INVENTION 
     The present invention provides fire resistant composite components having the necessary fire resistant capabilities to produce doors, door cores and building panels that can receive fire rated certifications. In most cases, the length and width of the fire rated door core will match the length and width specifications of the final door product. The dimensions of the fire rated door core will typically be in widths of three feet and four feet and having a length ranging from seven feet to ten feet. The thickness of the fire core can range from 1.50 inches to 2.00 inches. In some cases, an exterior banding may be added to the sides and ends of the fire rated door core. In other cases, an intumescent banding may be added between the exterior banding and fire rated door core. 
     More specifically, the present invention provides a composite product including gypsum in an amount of 70 to 90% by weight, fibers in an amount of 1.5 to 26% by weight substantially homogeneously distributed through the composite, and a rheology-modifying agent in an amount of 0.5 to 6% by weight. The composite is caused or allowed to cure to form a cured composite. The cured composite is a fire resistant component used in a fire-rated door core, a fire-rated door or a fire-rated building panel. The fire resistant component may include a building panel, a door panel, a door core, a door rail, a door stile, a door lock block, a door border, or a door insert. 
     In addition, the present invention provides a composite product including gypsum in an amount of 70 to 90% by weight, fibers in an amount of 1.5 to 5% by weight substantially homogeneously distributed through the composite, an aggregate in an amount of 1 to 4% by weight substantially homogeneously distributed through the composite, a starch in an amount of 2 to 7% by weight and a rheology-modifying agent in an amount of 0.5 to 4% by weight. The composite is caused or allowed to cure to form a cured composite. The fire resistant component may include a building panel, a door panel, a door core, a door rail, a door stile, a door lock block, a door border, or a door insert used in a fire-rated door core, a fire-rated door or a fire-rated building panel. 
     The present invention also provides a composite product including gypsum in an amount of 70 to 90% by weight, glass fibers in an amount of 2 to 10% by weight substantially homogeneously distributed through the composite, cellulose fibers in an amount of 2 to 8% by weight substantially homogeneously distributed through the composite, polyvinyl alcohol fibers in an amount of 1 to 4% by weight substantially homogeneously distributed through the composite, polypropylene fibers in an amount of 0.3 to 4% by weight substantially homogeneously distributed through the composite, and a rheology-modifying agent in an amount of 0.5 to 6% by weight. The composite is caused or allowed to cure to form a cured composite. The fire resistant component may include a building panel, a door panel, a door core, a door rail, a door stile, a door lock block, a door border, or a door insert used in a fire-rated door core, a fire-rated door or a fire-rated building panel. 
     Moreover, the present invention provides a core for a fire rated door that includes a fire resistant center panel and an extruded fire resistant border. The fire resistant center panel has a bottom, a top, a first side, a second side, a first end and a second end. The fire resistant center panel is made of a first fire resistant material that includes gypsum in an amount of 70 to 90% by weight, fibers in an amount of 1.5 to 5% by weight substantially homogeneously distributed through the composite, an aggregate in an amount of 1 to 4% by weight substantially homogeneously distributed through the composite, a starch in an amount of 2 to 7% by weight and a rheology-modifying agent in an amount of 0.5 to 4% by weight. The extruded fire resistant border is attached to the first side, the second side, the first end and the second end of the fire resistant center panel. The extruded fire resistant border is made of a second fire resistant material that includes gypsum in an amount of 70 to 90% by weight, glass fibers in an amount of 2 to 10% by weight substantially homogeneously distributed through the composite, cellulose fibers in an amount of 2 to 8% by weight substantially homogeneously distributed through the composite, polyvinyl alcohol fibers in an amount of 1 to 4% by weight substantially homogeneously distributed through the composite, polypropylene fibers in an amount of 0.3 to 4% by weight substantially homogeneously distributed through the composite, and a rheology-modifying agent in an amount of 0.5 to 6% by weight. 
     The present invention also provides a fire rated door that includes a core, a first decorative panel and a second decorative panel. The core includes: (a) a fire resistant center panel having a bottom, a top, a first side, a second side, a first end and a second end, wherein the fire resistant center panel is made of a first fire resistant material that includes gypsum in an amount of 70 to 90% by weight, fibers in an amount of 1.5 to 5% by weight substantially homogeneously distributed through the composite, an aggregate in an amount of 1 to 4% by weight substantially homogeneously distributed through the composite, a starch in an amount of 2 to 7% by weight and a rheology-modifying agent in an amount of 0.5 to 4% by weight, and (b) an extruded fire resistant border attached to the first side, the second side, the first end and the second end of the fire resistant center panel, wherein the extruded fire resistant border is made of a second fire resistant material that includes gypsum in an amount of 70 to 90% by weight, glass fibers in an amount of 2 to 10% by weight substantially homogeneously distributed through the composite, cellulose fibers in an amount of 2 to 8% by weight substantially homogeneously distributed through the composite, polyvinyl alcohol fibers in an amount of 1 to 4% by weight substantially homogeneously distributed through the composite, polypropylene fibers in an amount of 0.3 to 4% by weight substantially homogeneously distributed through the composite, and a rheology-modifying agent in an amount of 0.5 to 6% by weight. The first decorative panel is attached to the top of the fire resistant center panel and the extruded fire resistant border. The second decorative panel is attached to the bottom of the fire resistant center panel and the extruded fire resistant border. 
     The present invention is described in detail below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and further advantages of the invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a door core for a fire rated door in accordance with one embodiment of the present invention; 
         FIG. 2  is a perspective view of a door core for a fire rated door in accordance with another embodiment of the present invention; 
         FIGS. 3A-3D  are cross-sectional views of various interfaces of the center panel and the border of a door core in accordance with one embodiment of the present invention; 
         FIG. 4  is a perspective view of a door core for a fire rated door in accordance with another embodiment of the present invention; 
         FIG. 5  is a perspective view of a door core for a fire rated door in accordance with another embodiment of the present invention; 
         FIG. 6  is a perspective view of a door core for a fire rated door in accordance with another embodiment of the present invention; 
         FIG. 7  is a perspective view of a door core for a fire rated door in accordance with another embodiment of the present invention; 
         FIG. 8  is a perspective view of a door core for a fire rated door in accordance with another embodiment of the present invention; 
         FIG. 9  is a perspective view of a door core for a fire rated door in accordance with another embodiment of the present invention; 
         FIG. 10A  is an exploded perspective view of door core for a fire rated door in accordance with another embodiment of the present invention; 
         FIG. 10B  is a cross-sectional view of the door core of  FIG. 10A ; 
         FIG. 11A  is an exploded perspective view of a fire rated door in accordance with one embodiment of the present invention; 
         FIG. 11B  is a cross-sectional view of the fire rated door of  FIG. 11A ; 
         FIG. 11C  is a cross-sectional view of an alternative version of the fire rated door of  FIG. 11A ; 
         FIG. 12A  is an exploded perspective view of a fire rated door in accordance with another embodiment of the present invention; 
         FIG. 12B  is a cross-sectional view of the fire rated door of  FIG. 12A ; 
         FIG. 13A  is an exploded perspective view of a fire rated door in accordance with another embodiment of the present invention; 
         FIG. 13B  is a cross-sectional view of the fire rated door of  FIG. 13A ; 
         FIG. 13C  is a cross-sectional view of an alternative version of the fire rated door of  FIG. 13A ; 
         FIG. 14A  is an exploded perspective view of a fire rated door in accordance with another embodiment of the present invention; 
         FIG. 14B  is a cross-sectional view of the fire rated door of  FIG. 14A ; 
         FIG. 14C  is a cross-sectional view of an alternative version of the fire rated door of  FIG. 14A ; 
         FIG. 15A  is an exploded perspective view of a fire rated door in accordance with another embodiment of the present invention; 
         FIG. 15B  is a cross-sectional view of the fire rated door of  FIG. 15A ; 
         FIG. 16  is a flow chart of a method of manufacturing a door core for a fire rated door in accordance with one embodiment of the present invention; 
         FIG. 17  is a flow chart of a method of manufacturing a door core for a fire rated door in accordance with another embodiment of the present invention; and 
         FIG. 18  is a flow chart of a method of manufacturing a fire rated door in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention. The discussion herein relates primarily to fire rated doors, but it will be understood that the concepts of the present invention are applicable to any type of door. 
     The composite product of the present invention provides fire resistant components having the necessary fire resistant capabilities to produce doors, door cores and building panels that can receive fire rated certifications. The composite includes gypsum in an amount of 70 to 90% by weight, fibers in an amount of 1.5 to 26% by weight substantially homogeneously distributed through the composite, and a rheology-modifying agent in an amount of 0.5 to 6% by weight. The gypsum can be 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% or 90% by weight or other incremental percentage between. The fibers can be 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, 20%, 20.5%, 21%, 21.5%, 22%, 22.5%, 23%, 23.5%, 24%, 24.5%, 25%, 25.5% or 26% by weight or other incremental percentage between. The fibers can be glass fibers, cellulose fibers polyvinyl alcohol fibers, polypropylene fibers, or a combination thereof. Other types of fibers can be used. The rheology-modifying agent can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9% or 6% by weight or other incremental percentage between. The rheology-modifying agent can be hydroxypropoyl methyl celluose (HPMC), methyl hydroxyethyl cellulose (MHEC), hydroxyethyl cellulose (HEC) or carboxymethyl cellulose (CMC). Other types of rheology-modifying agent can be used. 
     The composite is caused or allowed to cure to form a cured composite. The actual component weights used will depend on the density desired for the fire resistant component. The cured composite is a fire resistant component used in a fire-rated door core, a fire-rated door or a fire-rated building panel. The fire resistant component may include a building panel, a door panel, a door core, a door rail, a door stile, a door lock block, a door border, or a door insert. The fire resistant component typically has a cross-sectional thickness of 0.125 inches to 2 inches, a width of 1 inch to 4 feet and a length of 3 to 10 feet. Moreover and unlike many prior art composite materials, the composite product in accordance with the present invention does not include any cement or flyash. 
     The door core of the present invention provides the fire resistant capabilities necessary to receive the necessary certification. The length and width of the fire core will match the length and width specifications of the final door product. The dimensions of the fire core will typically be in widths of three feet and four feet and having a length ranging from seven feet to ten feet. The thickness of the door core will typically be between 0.125″ and 1.5″. A door manufacturer can use any of the completed core designs described herein as the fire resistant core of the manufacturer&#39;s fire-rated door. The resulting fire rated door can have fire ratings of 20-30, 45, 60, 90 or 120 minutes depending on the configuration and materials used. The manufacturer will typically finish the final door product by adding a final piece of wood or veneer to the door to provide the aesthetic appeal of the product. 
     Now referring to  FIG. 1 , a perspective view of a door core  100  for a fire rated door in accordance with one embodiment of the present invention is shown. The core  100  includes a fire resistant center panel  102  and an extruded fire resistant border  104 . The fire resistant center panel  102  has a bottom (not shown), a top  106 , a first side  108 , a second side  110 , a first end  112  and a second end  114 . The fire resistant center panel  102  is made of a first fire resistant material that is either pourable or extrudable. The first fire resistant material can be composed of gypsum, water, glass, a ceramic material, a cellulose or fiber material, and one or more binding agents. One example of such a material in accordance with the present invention is: 
                            First Fire Resistant Material                             Component   Range (% Wt.)                       Gypsum   70 to 90           Glass Fiber   1.5 to 5             Lightweight Aggregate   1 to 4           Starch   2 to 7           Rheology-Modifying Agent   0.5 to 4                          
The gypsum can be 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% or 90% by weight or other incremental percentage between. The glass fibers can be 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% by weight or other incremental percentage between. The glass fibers can have a diameter of 6 mm to 25 mm. The lightweight aggregate can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5% or 4% by weight or other incremental percentage between. The lightweight aggregate, such as Poraver® porous glass spheres, can have average particle diameters of 1 to 2 mm or 2 to 4 mm. The starch can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5% or 7% by weight or other incremental percentage between. The starch is a pregelatinized or cook-up starch. The rheology-modifying agent can be cellulose ether, such as hydroxypropoyl methyl celluose (HPMC), methyl hydroxyethyl cellulose (MHEC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC) or similar materials. The rheology-modifying agent can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9% or 4% by weight or other incremental percentage between. Other materials can be substituted as will be appreciated by those skilled in the art.
 
     The extruded fire resistant border  104  is made of a second fire resistant material having a higher density than the first fire resistant material so that second fire resistant material has holding capacity (e.g., fasteners will adhere to the second fire resistant material and remain fixed once installed) and can be shaped using an extrusion process. One example of such a material in accordance with the present invention is: 
                            Second Fire Resistant Material                             Component   Range (% Wt.)                       Gypsum   70 to 90           Glass Fiber    2 to 10           Cellulose Fiber   2 to 8           Polyvinyl Alcohol (PVA) Fiber   1 to 4           Polypropylene (PP) Fiber   0.3 to 4             Rheology-Modifying Agent   0.5 to 6                          
The gypsum can be 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% or 90% by weight or other incremental percentage between. The glass fibers can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10% by weight or other incremental percentage between. The glass fibers can have a diameter of 6 mm to 25 mm. The cellulose fibers can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5% or 8% by weight or other incremental percentage between. The cellulose fibers can be hardwood or softwood fiber. The polyvinyl alcohol (PVA) fibers can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5% or 4% by weight or other incremental percentage between. The PVA fibers can have a diameter of 6 mm to 10 mm with a decitex of approximately 15. The polypropylene (PP) fibers can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9% or 4% by weight or other incremental percentage between. The PP fibers can have a diameter of 6 mm to 25 mm. The rheology-modifying agent can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9% or 6% by weight or other incremental percentage between. The rheology-modifying agent can be a cellulose ether, such as hydroxypropoyl methyl cellulose (HPMC), methyl hydroxyethyl cellulose (MHEC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC) or similar materials. Other materials can be substituted as will be appreciated by those skilled in the art.
 
     The extruded fire resistant border  104  can be made of a molded piece of the second fire resistant material (e.g.,  FIG. 1 ), or stiles and rails made of the second fire resistant material that are glued or fastened together (e.g.,  FIG. 4 ). The extruded fire resistant border  104  is attached to the first side  108 , the second side  110 , the first end  112  and the second end  114  of the fire resistant center panel  102  using glue, fasteners or a bonding process (e.g., pouring the first fire resistant material into a “mold” formed by the extruded fire resistant border  104 ). Several examples of the interface between the extruded fire resistant border  104  and the fire resistant center panel  102  are shown in  FIGS. 3A-3D . 
     The physical dimensions of the core  100  and other cores described below in reference to  FIGS. 2-10 , the fire resistant center panel  102  and the extruded fire resistant border  104  will vary depending on the specific application for which the door core is manufactured. Typical dimensions may include, but are not limited to, 1.5″ to 2.0″ thickness of the fire resistant panel  102  and the extruded fire resistant border  104 , a 7′ to 10′ overall length of the core  100 , a 3′ to 4′ overall width of the core  100 , a 1″ to 5″ width of the top and bottom portions (rails) of the extruded fire resistant border  104 , and a 1″ to 5″ (e.g., 1.625″) width of the left and right portion (stiles) of the extruded fire resistant border  104 . 
     The core  100  and other cores described below in reference to  FIGS. 2-10  can be manufactured by assembling the fire resistant border  104 , pouring the first fire resistant material in the area formed by the fire resistant border  104 , and baking the core  100 . Alternatively, the core  100  can be manufactured by creating sheets of the first fire resistant material and the second fire resistant material using an extrusion process, gang ripping the sheets of the second fire resistant material to make the fire resistant border stiles and rails, finishing the extruded stiles and rails to profile or cut them to the desired smoothness, size and shape, and gluing or fastening the fire resistant border stiles and rails to the fire resistant center panel  102 . 
     Referring now to  FIG. 2 , a perspective view of a door core  200  for a fire rated door in accordance with another embodiment of the present invention is shown. The core  200  includes a first fire resistant center panel  102   a , a second fire resistant center panel  102   b  and an extruded fire resistant border  104 . The first fire resistant center panel  102   a  has a bottom (not shown), a top  106   a , a first side  108   a , a second side  110   a , a first end  112  and a second end  202 . The second fire resistant center panel  102   b  has a bottom (not shown), a top  106   b , a first side  108   b , a second side  110   b , a first end  204  and a second end  114 . The first fire resistant center panel  102   a  and second fire resistant center panel  102   b  are made of the first fire resistant material that is either pourable or extrudable. The extruded fire resistant border  104  is made of the second fire resistant material having a higher density than the first fire resistant material so that second fire resistant material has holding capacity (e.g., fasteners will adhere to the second fire resistant material and remain fixed once installed) and can be shaped using an extrusion process. The extruded fire resistant border  104  also includes a center rail  206  made of the second fire resistant material. The extruded fire resistant border  104  can be made of a molded piece of the second fire resistant material (e.g.,  FIG. 2 ), or stiles and rails made of the second fire resistant material that are glued or fastened together (e.g.,  FIG. 5 ). The extruded fire resistant border  104  (including center rail  206 ) is attached to the first side  108   a , the second side  110   a , the first end  112   a  and the second end  202  of the fire resistant center panel  102   a  and the first side  108   b , the second side  110   b , the first end  204  and the second end  114  of the second fire resistant center panel  102   b  using glue, fasteners or a bonding process (e.g., pouring the first fire resistant material into a “mold” formed by the extruded fire resistant border  104 ). Several examples of the interface between the extruded fire resistant border  104  and the fire resistant center panels  102   a ,  102   b  are shown in  FIGS. 3A-3D . 
     The physical dimensions of the core  200  and other cores described below in reference to  FIGS. 3-10 , the fire resistant center panels  102   a ,  102   b  and the extruded fire resistant border  104  will vary depending on the specific application for which the door core is manufactured. Typical dimensions may include, but are not limited to, 1.5″ thickness of the fire resistant panels  102   a ,  102   b  and the extruded fire resistant border  104 , a 7′ to 10′ overall length of the core  100 , a 3′ to 4′ overall width of the core  100 , a 1″ to 5″ width of the top, bottom and center portions (rails) of the extruded fire resistant border  104 , and a 1″ to 5″ (e.g., 1.625″) width of the left and right portion (stiles) of the extruded fire resistant border  104 . 
     Now referring to  FIGS. 3A-3D , cross-sectional views of various interfaces of the center panel  102  and the border  104  of a door core  100 ,  200 ,  400 ,  500 ,  600 ,  700 ,  800  and  900  in accordance with one embodiment of the present invention is shown.  FIG. 3A  shows a straight interface wherein a glue is used to attach the extruded fire resistant border  104  to the fire resistant center panel  102 . Note that the straight interface can be angled with respect to the top of the fire resistant center panel  102  instead of being substantially perpendicular. As shown in  FIGS. 3B-3D , the extruded fire resistant border  104  can be attached to the fire resistant center panel  102  with a set of male-female connectors  300  formed in the extruded fire resistant border  104  and the fire resistant center panel  102 . The male-female connectors can be triangular-shaped  300   a  ( FIG. 3B ), curved-shaped  300   b  ( FIG. 3C ) or  300   c  ( FIG. 3D ), rectangular-shaped, angled, tongue-and-groove, or a combination thereof. A glue is typically used is used to attach the extruded fire resistant border  104  to the fire resistant center panel  102 , but fasteners or a bonding process can also be used. 
     Referring now to  FIG. 4 , a perspective view of a door core  400  for a fire rated door in accordance with another embodiment of the present invention is shown. The core  400  includes a fire resistant center panel  102  and an extruded fire resistant border  104 . The fire resistant center panel  102  has a bottom (not shown), a top  106 , a first side  108 , a second side  110 , a first end  112  and a second end  114 . The fire resistant center panel  102  is made of the first fire resistant material that is either pourable or extrudable. The extruded fire resistant border  104  is made up of a first stile  402  (left), a second stile  404  (right), a first rail  406  (top) and a second rail  408  (bottom). The first stile  402  (left), second stile  404  (right), first rail  406  (top) and second rail  408  (bottom) are made of the second fire resistant material having a higher density than the first fire resistant material so that second fire resistant material has holding capacity (e.g., fasteners will adhere to the second fire resistant material and remain fixed once installed) and can be shaped using an extrusion process. The first stile  402  (left), second stile  404  (right), first rail  406  (top) and second rail  408  (bottom) are glued or fastened together and to the fire resistant center panel  102 . The first stile  402  (left) is attached to the first side  108  of the fire resistant center panel  102  using glue, fasteners or a bonding process. The second stile  404  (right) is attached to the second side  110  of the fire resistant center panel  102  using glue, fasteners or a bonding process. The first rail  406  (top) is attached to the first end  112  of the fire resistant center panel  102  using glue, fasteners or a bonding process. The second rail  408  (top) is attached to the second end  114  of the fire resistant center panel  102  using glue, fasteners or a bonding process. Several examples of the interface between the stiles  402 ,  404 , the rails  406 ,  408 , and the fire resistant center panel  102  are shown in  FIGS. 3A-3D . 
     Now referring to  FIG. 5 , a perspective view of a door core  500  for a fire rated door in accordance with another embodiment of the present invention is shown. The core  500  includes a first fire resistant center panel  102   a , a second fire resistant panel  102   b  and an extruded fire resistant border  104 . The first fire resistant center panel  102   a  has a bottom (not shown), a top  106   a , a first side  108   a , a second side  110   a , a first end  112   a  and a second end  202 . The second fire resistant center panel  102   b  has a bottom (not shown), a top  106   b , a first side  108   b , a second side  110   b , a first end  204  and a second end  114 . The first fire resistant center panel  102   a  and second fire resistant center panel  102   b  are made of the first fire resistant material that is either pourable or extrudable. The extruded fire resistant border  104  is made up of a first stile  402  (left), a second stile  404  (right), a first rail  406  (top), a second rail  408  (bottom) and a third rail or insert  502  (center). The first stile  402  (left), second stile  404  (right), first rail  406  (top), second rail  408  (bottom) and third rail or insert  502  (center) are made of the second fire resistant material having a higher density than the first fire resistant material so that second fire resistant material has holding capacity (e.g., fasteners will adhere to the second fire resistant material and remain fixed once installed) and can be shaped using an extrusion process. The first stile  402  (left), second stile  404  (right), first rail  406  (top), second rail  408  (bottom), third rail or insert  502  (center) are glued or fastened together and to the fire resistant center panels  102   a  and  102   b . The first stile  402  (left) is attached to the first side  108   a ,  108   b  of the fire resistant center panels  102   a ,  102   b  using glue, fasteners or a bonding process. The second stile  404  (right) is attached to the second side  110   a ,  110   b  of the fire resistant center panels  102   a ,  102   b  using glue, fasteners or a bonding process. The first rail  406  (top) is attached to the first end  112  of the first fire resistant center panel  102   a  using glue, fasteners or a bonding process. The second rail  408  (bottom) is attached to the second end  114  of the second fire resistant center panel  102   b  using glue, fasteners or a bonding process. The third rail or insert  502  (center) is attached to the second end  202  of the first fire resistant center panel  102   a  and the first end  204  of the second fire resistant panel  102   b  using glue, fasteners or a bonding process. Several examples of the interface between the stiles  402 ,  404 , the rails  406 ,  408 , and the fire resistant center panels  102   a ,  102   b  are shown in  FIGS. 3A-3D . These interfaces can also be used between the fire resistant center panels  102   a ,  102   b  and the third rail or insert  502  (center). 
     Referring now to  FIG. 6 , a perspective view of a door core  600  for a fire rated door in accordance with another embodiment of the present invention is shown. The core  600  includes a fire resistant center panel  102 , an extruded fire resistant border  104  and a lock block  602 . The fire resistant center panel  102  has a bottom (not shown), a top  106 , a first side  108 , a second side  110 , a first end  112 , a second end  114  and a cutout or notch  604  disposed in the first side  108 . The fire resistant center panel  102  is made of the first fire resistant material that is either pourable or extrudable. The lock block  602  is disposed within the cutout or notch  604  of the fire resistant center panel  102 . The lock block  602  is made of the second fire resistant material and is sized to accommodate a door handle, lockset or other door hardware. The extruded fire resistant border  104  is made up of a first stile  402  (left), a second stile  404  (right), a first rail  406  (top) and a second rail  408  (bottom). The first stile  402  (left), second stile  404  (right), first rail  406  (top) and second rail  408  (bottom) are made of the second fire resistant material having a higher density than the first fire resistant material so that second fire resistant material has holding capacity (e.g., fasteners will adhere to the second fire resistant material and remain fixed once installed) and can be shaped using an extrusion process. The first stile  402  (left), second stile  404  (right), first rail  406  (top) and second rail  408  (bottom) are glued or fastened together and to the fire resistant center panel  102  and lock block  602 . The first stile  402  (left) is attached to the first side  108  of the fire resistant center panel  102  and the lock block  602  using glue, fasteners or a bonding process. The second stile  404  (right) is attached to the second side  110  of the fire resistant center panel  102  using glue, fasteners or a bonding process. The first rail  406  (top) is attached to the first end  112  of the fire resistant center panel  102  using glue, fasteners or a bonding process. The second rail  408  (top) is attached to the second end  114  of the fire resistant center panel  102  using glue, fasteners or a bonding process. Several examples of the interface between the stiles  402 ,  404 , the rails  406 ,  408 , and the fire resistant center panel  102  are shown in  FIGS. 3A-3D . These interfaces can also be used between the lock block  602 , the fire resistant center panel  102  and the first stile  402  (left). 
     Now referring to  FIG. 7 , a perspective view of a door core  700  for a fire rated door in accordance with another embodiment of the present invention is shown. The core  700  includes a first fire resistant center panel  102   a , a second fire resistant panel  102   b  and an extruded fire resistant border  104 . The first fire resistant center panel  102   a  has a bottom (not shown), a top  106   a , a first side  108   a , a second side  110   a , a first end  112   a  and a second end  202 . The second fire resistant center panel  102   b  has a bottom (not shown), a top  106   b , a first side  108   b , a second side  110   b , a first end  204  and a second end  114 . The first fire resistant center panel  102   a  and second fire resistant center panel  102   b  are made of the first fire resistant material that is either pourable or extrudable. The extruded fire resistant border  104  is made up of a first stile  402  (left), a second stile  404  (right), a first rail  406  (top), a second rail  408  (bottom) and a third rail or insert  702  (middle). The first stile  402  (left), second stile  404  (right), first rail  406  (top), second rail  408  (bottom) and third rail or insert  702  (middle) are made of the second fire resistant material having a higher density than the first fire resistant material so that second fire resistant material has holding capacity (e.g., fasteners will adhere to the second fire resistant material and remain fixed once installed) and can be shaped using an extrusion process. The first stile  402  (left), second stile  404  (right), first rail  406  (top), second rail  408  (bottom), third rail or insert  702  (middle) are glued or fastened together and to the fire resistant center panels  102   a  and  102   b . The first stile  402  (left) is attached to the first side  108   a ,  108   b  of the fire resistant center panels  102   a ,  102   b  using glue, fasteners or a bonding process. The second stile  404  (right) is attached to the second side  110   a ,  110   b  of the fire resistant center panels  102   a ,  102   b  using glue, fasteners or a bonding process. The first rail  406  (top) is attached to the first end  112  of the first fire resistant center panel  102   a  using glue, fasteners or a bonding process. The second rail  408  (bottom) is attached to the second end  114  of the second fire resistant center panel  102   b  using glue, fasteners or a bonding process. The third rail or insert  702  (middle) is attached to the second end  202  of the first fire resistant center panel  102   a  and the first end  204  of the second fire resistant panel  102   b  using glue, fasteners or a bonding process. The third rail or insert  702  (middle) is positioned and sized (e.g., 5″ to 10″ wide) to accept various attachments, such as a crash bar. Several examples of the interface between the stiles  402 ,  404 , the rails  406 ,  408 , and the fire resistant center panels  102   a ,  102   b  are shown in  FIGS. 3A-3D . These interfaces can also be used between the fire resistant center panels  102   a ,  102   b  and the third rail or insert  702  (middle). 
     Referring now to  FIG. 8 , a perspective view of a door core  800  for a fire rated door in accordance with another embodiment of the present invention is shown. The core  800  includes a first fire resistant center panel  102   a , a second fire resistant center panel  102   b , an extruded fire resistant border  104  and a lock block  602 . The first fire resistant center panel  102   a  has a bottom (not shown), a top  106   a , a first side  108   a , a second side  110   a , a first end  112   a , a second end  202  and a cutout or notch  604  disposed in the first side  108   a . The second fire resistant center panel  102   b  has a bottom (not shown), a top  106   b , a first side  108   b , a second side  110   b , a first end  204  and a second end  114 . The first fire resistant center panel  102   a  and second fire resistant center panel  102   b  are made of the first fire resistant material that is either pourable or extrudable. The lock block  602  is disposed within the cutout or notch  604  of the first fire resistant center panel  102   a . The lock block  602  is made of the second fire resistant material and is sized to accommodate a door handle, lockset or other door hardware. The extruded fire resistant border  104  is made up of a first stile  402  (left), a second stile  404  (right), a first rail  406  (top), a second rail  408  (bottom) and a third rail or insert  702  (middle). The first stile  402  (left), second stile  404  (right), first rail  406  (top), second rail  408  (bottom) and third rail or insert  702  (middle) are made of the second fire resistant material having a higher density than the first fire resistant material so that second fire resistant material has holding capacity (e.g., fasteners will adhere to the second fire resistant material and remain fixed once installed) and can be shaped using an extrusion process. The first stile  402  (left), second stile  404  (right), first rail  406  (top), second rail  408  (bottom), third rail or insert  702  (middle) are glued or fastened together and to the fire resistant center panels  102   a ,  102   b  and lock block  602 . The first stile  402  (left) is attached to the first side  108   a ,  108   b  of the fire resistant center panels  102   a ,  102   b  and the lock block  602  using glue, fasteners or a bonding process. The second stile  404  (right) is attached to the second side  110   a ,  110   b  of the fire resistant center panels  102   a ,  102   b  using glue, fasteners or a bonding process. The first rail  406  (top) is attached to the first end  112  of the first fire resistant center panel  102   a  using glue, fasteners or a bonding process. The second rail  408  (bottom) is attached to the second end  114  of the second fire resistant center panel  102   b  using glue, fasteners or a bonding process. The third rail or insert  702  (middle) is attached to the second end  202  of the first fire resistant center panel  102   a , the first end  204  of the second fire resistant panel  102   b  and the lock block  602  using glue, fasteners or a bonding process. The third rail or insert  702  (middle) is positioned and sized (e.g., 5″ to 10″ wide) to accept various attachments, such as a crash bar. Several examples of the interface between the stiles  402 ,  404 , the rails  406 ,  408 , and the fire resistant center panels  102   a ,  102   b  are shown in  FIGS. 3A-3D . These interfaces can also be used between the lock block  602 , the fire resistant center panel  102   a , the first stile  402  (left) and the third rail or insert  702  (middle). 
     Now referring to  FIG. 9 , a perspective view of a door core  900  for a fire rated door in accordance with another embodiment of the present invention is shown. The core  900  includes a center panel  902  and an extruded fire resistant border  104 . The center panel  902  has a bottom (not shown), a top  106 , a first side  108 , a second side  110 , a first end  112  and a second end  114 . The center panel  902  is made of a corrugated filler (e.g., cardboard, etc.) having a plurality of voids (e.g., honeycomb shaped, hexagon shaped, triangular shaped, etc.) and may be filled with an acoustical insulating material (e.g., fiberglass, foam, etc.). The extruded fire resistant border  104  is made up of a first stile  402  (left), a second stile  404  (right), a first rail  406  (top) and a second rail  408  (bottom). The first stile  402  (left), second stile  404  (right), first rail  406  (top) and second rail  408  (bottom) are made of the second fire resistant material having a higher density than the first fire resistant material so that second fire resistant material has holding capacity (e.g., fasteners will adhere to the second fire resistant material and remain fixed once installed) and can be shaped using an extrusion process. The first stile  402  (left), second stile  404  (right), first rail  406  (top) and second rail  408  (bottom) are glued or fastened together and to the center panel  902 . The first stile  402  (left) is attached to the first side  108  of the center panel  902  using glue, fasteners or a bonding process. The second stile  404  (right) is attached to the second side  110  of the center panel  902  using glue, fasteners or a bonding process. The first rail  406  (top) is attached to the first end  112  of the center panel  902  using glue, fasteners or a bonding process. The second rail  408  (top) is attached to the second end  114  of the center panel  902  using glue, fasteners or a bonding process. Several examples of the interface between the stiles  402 ,  404 , the rails  406 ,  408 , and the fire resistant center panel  902  are shown in  FIGS. 3A-3D . Note that the center panel  902  is not suitable for forming a fire resistant door alone. Fire resistant materials or panels must be installed on the top  106  and bottom (not shown) of the center panel  902  in order to make a fire resistant door. For example, the center panel  902  can be used in the doors  1100  ( FIG. 11A ),  1200  ( FIG. 12A ) and  1300  ( FIG. 13A ) if panels  1102 ,  1102  and  1302 , respectively, are made of a fire resistant material (e.g., the second fire resistant material, etc.). 
     Referring now to  FIG. 10A , an exploded perspective view of door core  1000  for a fire rated door in accordance with another embodiment of the present invention is shown. The core  1000  includes a fire resistant center panel  102  or  1002  disposed between a top insulating panel  902   a  and a bottom insulating panel  902   b , and an extruded fire resistant border  104  around the three panels  902   a ,  102  (or  1002 ) and  902   b . The fire resistant center panel  102  is made of the first fire resistant material that is either pourable or extrudable. The fire resistant center panel  1002  is made of the second fire resistant material that is either pourable or extrudable. The top insulating panel  902   a  and bottom insulating panel  902   b  are made of a corrugated filler (e.g., cardboard, etc.) having a plurality of voids (e.g., honeycomb shaped, hexagon shaped, triangular shaped, etc.) and may be filled with an acoustical insulating material (e.g., fiberglass, foam, etc.). The three panels  902   a ,  102  (or  1002 ) and  902   b  are typically glued together. The fire resistant center panel  102  or  1002  has a bottom (not shown), a top  106 , a first side  108 , a second side  110 , a first end  112  and a second end  114 . The extruded fire resistant border  104  is made up of a first stile  402  (left), a second stile  404  (right), a first rail  406  (top) and a second rail  408  (bottom). The first stile  402  (left), second stile  404  (right), first rail  406  (top) and second rail  408  (bottom) are made of the second fire resistant material having a higher density than the first fire resistant material so that second fire resistant material has holding capacity (e.g., fasteners will adhere to the second fire resistant material and remain fixed once installed) and can be shaped using an extrusion process. The first stile  402  (left), second stile  404  (right), first rail  406  (top) and second rail  408  (bottom) are glued or fastened together and to the three panels  902   a ,  102  (or  1002 ) and  902   b . The first stile  402  (left) is attached to the first side  108  of the three panels  902   a ,  102  (or  1002 ) and  902   b  using glue, fasteners or a bonding process. The second stile  404  (right) is attached to the second side  110  of the three panels  902   a ,  102  (or  1002 ) and  902   b  using glue, fasteners or a bonding process. The first rail  406  (top) is attached to the first end  112  of the three panels  902   a ,  102  (or  1002 ) and  902   b  using glue, fasteners or a bonding process. The second rail  408  (top) is attached to the second end  114  of the three panels  902   a ,  102  (or  1002 ) and  902   b  using glue, fasteners or a bonding process. Several examples of the interface between the stiles  402 ,  404 , the rails  406 ,  408 , and the fire resistant center panel  102  are shown in  FIGS. 3A-3D .  FIG. 10B  is a cross-sectional view of the door core of  FIG. 10A . 
     Note that the cores shown in  FIGS. 1-10  and described above may also include a top panel attached to the top of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000 , or a bottom panel attached to the bottom of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000 , or both the top panel and the bottom panel attached to the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000 . Example of such a configuration is shown in  FIGS. 13A and 14A . The top panel or the bottom panel can be a lignocellulosic substrate, a wood, a wood composite, a medium density fiberboard, a high density fiberboard, a particleboard, a masonite, a fiberglass, a metal, a plastic, a fire resistant panel, one or more protective layers or a combination thereof. The one or more protective layers can be a fire resistant material, a blast resistant material, a ballistic resistant material, a shielding material, a chemical resistant material, a biohazard resistant material, a radiation resistant material, a dampening material, a grounding material, insulating material or a combination thereof. For example, the one or more protective layers can be one or more gypsum boards, one or more metallic sheets, one or more lead sheets, one or more Kevlar sheets, one or more ceramic sheets, a layer of urethane foam, a layer of graphite, a wire mesh or a combination thereof. Moreover, the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  and/or top or bottom panels can be coated with an intumescent or fire resistant material. Finally, note that the rails shown in the figures can extend to the sides of the door or core such that the stiles extend between the top and bottom rails. 
     Referring now to  FIG. 11A , an exploded perspective view of a fire rated door  1100  in accordance with one embodiment of the present invention is shown. The fire rated door  1100  includes a core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  (see  FIGS. 1-10  and associated description for details), a first decorative panel  1102  and a second decorative panel  1104 . The first and second decorative panel  1102  and  1104  can be a lignocellulosic substrate, a wood, a wood composite, a medium density fiberboard, a high density fiberboard, a particleboard, a masonite, a fiberglass, a metal, a plastic, a fire resistant material or a combination thereof. The first decorative panel  1102  is attached to the top of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  using glue. The second decorative panel  1104  is attached to the bottom of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  using glue. Note that the glue may have fire resistant properties or contain an intumescent material. The first and second decorative panels  1102  and  1104  have a slightly larger length and width to accommodate an exterior banding  1106  attached to each side and end of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000 . The exterior banding  1106  can be a first banding  1106   a , a second banding  1106   b , a third banding  1106   c  and a fourth banding  1106   d .  FIG. 11B  shows a cross-sectional view of the fire rated door  1100 .  FIG. 11C  shows a cross-sectional view of an alternative version of the fire rated door  1100  in which an intumescent banding material  1108  can also be disposed between the exterior banding  1106  and the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000 . 
     Now referring to  FIG. 12A , an exploded perspective view of a fire rated door  1200  in accordance with another embodiment of the present invention is shown. The fire rated door  1200  includes a core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  (see  FIGS. 1-10  and associated description for details), a first decorative panel  1102  and a second decorative panel  1104 . The first and second decorative panel  1102  and  1104  can be a lignocellulosic substrate, a wood, a wood composite, a medium density fiberboard, a high density fiberboard, a particleboard, a masonite, a fiberglass, a metal, a plastic, a fire resistant material or a combination thereof. Note that the first and second decorative panels  1102  and  1104  may also have fire resistant properties. The first decorative panel  1102  is attached to the top of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  using glue. The second decorative panel  1104  is attached to the bottom of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  using glue. Note that the glue may have fire resistant properties or contain an intumescent material. The first and second decorative panels  1102  and  1104  have the same length and width as the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000 . As a result, additional banding, rails and stiles are not needed.  FIG. 12B  shows a cross-sectional view of the fire rated door  1200 . 
     Referring now to  FIG. 13A , an exploded perspective view of a fire rated door  1300  in accordance with another embodiment of the present invention is shown. The fire rated door  1300  includes a core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  (see  FIGS. 1-10  and associated description for details), a first protective panel or layer  1302  (also referred to as a top panel), a first decorative panel  1102 , a second protective panel or layer  1304  (also referred to as a bottom panel) and a second decorative panel  1104 . The first protective panel or layer  1302  and the second protective panel or layer  1304  can be a fire resistant material, a blast resistant material, a ballistic resistant material, a shielding material, a chemical resistant material, a biohazard resistant material, a radiation resistant material, a dampening material, a grounding material, insulating material or a combination thereof. For example, the first protective panel or layer  1302  and the second protective panel or layer  1304  can be one or more gypsum boards, one or more metallic sheets, one or more lead sheets, one or more Kevlar sheets, one or more ceramic sheets, a layer of urethane foam, a layer of graphite, a wire mesh or a combination thereof. A 120 minute fire rated door can be obtained by using a dense fire resistant material, such as second fire resistant material, as the first and second protective panels or layers  1302  and  1304 . The first and second decorative panel  1102  and  1104  can be a lignocellulosic substrate, a wood, a wood composite, a medium density fiberboard, a high density fiberboard, a particleboard, a masonite, a fiberglass, a metal, a plastic, a fire resistant material or a combination thereof. The first decorative panel  1102  is attached to the top of the first protective panel or layer  1302  using glue. The first protective panel or layer  1302  is attached to the top of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  using glue. The second decorative panel  1104  is attached to the bottom of the second protective panel or layer  1304  using glue. The second protective panel or layer  1304  is attached to the bottom of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  using glue. Note that the glue may have fire resistant properties or contain an intumescent material. The first and second decorative panels  1102 ,  1104  and first and second protective panels or layers  1302 ,  1304  have the same length and width as the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000 . As a result, additional banding, rails and stiles are not needed.  FIG. 13B  shows a cross-sectional view of the fire rated door  1300 .  FIG. 13C  shows a cross-sectional view of an alternative version of the fire rated door  1300  in which the first and second decorative panels  1102  and  1104  have a slightly larger length and width to accommodate an exterior banding  1106  attached to each side and end of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000 . As shown in  FIG. 11A , the exterior banding  1106  can be a first banding  1106   a , a second banding  1106   b , a third banding  1106   c  and a fourth banding  1106   d . In addition, an alternative version of the fire rated door  1300  can be fabricated in which an intumescent banding material  1108  is disposed between the exterior banding  1106  and the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  (see  FIG. 11C ). 
     Now referring to  FIG. 14A , an exploded perspective view of a fire rated door  1400  in accordance with another embodiment of the present invention is shown. The fire rated door  1400  includes a core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  (see  FIGS. 1-10  and associated description for details), a first insulating panel or layer  1402 , a first decorative panel  1102 , a second insulating panel or layer  1404  and a second decorative panel  1104 . The first insulating panel or layer  1402  and the second protective panel or layer  1404  is made of a corrugated filler (e.g., cardboard, etc.) having a plurality of voids (e.g., honeycomb shaped, hexagon shaped, triangular shaped, etc.) filled with an insulating and/or fire resistant material (e.g., fiberglass, foam, etc.). The first and second decorative panel  1102  and  1104  can be a lignocellulosic substrate, a wood, a wood composite, a medium density fiberboard, a high density fiberboard, a particleboard, a masonite, a fiberglass, a metal, a plastic, a fire resistant material or a combination thereof. The first decorative panel  1102  is attached to the top of the first insulating panel or layer  1402  using glue. The first insulating panel or layer  1402  is attached to the top of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  using glue. The second decorative panel  1104  is attached to the bottom of the second insulating panel or layer  1404  using glue. The second insulating panel or layer  1404  is attached to the bottom of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  using glue. Note that the glue may have fire resistant properties or contain an intumescent material. The first and second decorative panels  1102 ,  1104  and first and second insulating panels or layers  1402 ,  1404  have the same length and width as the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000 . As a result, additional banding, rails and stiles are not needed.  FIG. 14B  shows a cross-sectional view of the fire rated door  1400 .  FIG. 14C  shows a cross-sectional view of an alternative version of the fire rated door  1400  in which the first and second decorative panels  1102  and  1104  have a slightly larger length and width to accommodate an exterior banding  1106  attached to each side and end of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000 . As shown in  FIG. 11A , the exterior banding  1106  can be a first banding  1106   a , a second banding  1106   b , a third banding  1106   c  and a fourth banding  1106   d . In addition, an alternative version of the fire rated door  1400  can be fabricated in which an intumescent banding material  1108  is disposed between the exterior banding  1106  and the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  (see  FIG. 11C ). 
     Referring now to  FIG. 15A , an exploded perspective view of a fire rated door  1500  in accordance with another embodiment of the present invention is shown. The fire rated door  1500  includes a core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  (see  FIGS. 1-10  and associated description for details), a first decorative panel  1102 , a second decorative panel  1104  and four rails  1502 . Alternatively, the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  can be a single sheet of fire resistant material, including, but not limited to the first fire resistant material. The back side of first and second decorative panel  1102  and  1104  include a notch or cutout  1504  along the left and right sides that is sized to fit each rail  1502 . Each rail  1502  is made of the second fire resistant material or other suitable material. In one example, the rails have a height of 11/16″ and width of 1″. The first and second decorative panel  1102  and  1104  can be a lignocellulosic substrate, a wood, a wood composite, a medium density fiberboard, a high density fiberboard, a particleboard, a masonite, a fiberglass, a metal, a plastic, a fire resistant material or a combination thereof. Note that the first and second decorative panels  1102  and  1104  may also have fire resistant properties. The first decorative panel  1102  is attached to the top of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  or single sheet of fire resistant material using glue. The second decorative panel  1104  is attached to the bottom of the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  or single sheet of fire resistant material using glue. Note that the glue may have fire resistant properties or contain an intumescent material. The first and second decorative panels  1102  and  1104  have the same length and width as the core  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  or  1000  or single sheet of fire resistant material. As a result, additional banding, rails and stiles are not needed.  FIG. 15B  shows a cross-sectional view of the fire rated door  1400 . 
     Now referring to  FIG. 16 , a flow chart of a method  1600  of manufacturing a door core for a fire rated door in accordance with one embodiment of the present invention is shown. A fire resistant center panel having a bottom, a top, a first side, a second side, a first end and a second end is provided in block  1602 , wherein the fire resistant center panel is made of a first fire resistant material. A first stile of an extruded fire resistant border is attached to the first side of the fire resistant center panel in block  1604 , wherein the extruded fire resistant border is made of a second fire resistant material having a higher density than the first fire resistant material. A second stile of the extruded fire resistant border is attached to the second side of the fire resistant center panel in block  1606 . A first rail of the extruded fire resistant border is attached to the first end of the fire resistant center panel and the first stile and the second stile of the extruded fire resistant border in block  1608 . A second rail of the extruded fire resistant border is attached to the second end of the fire resistant center panel and the first stile and the second stile of the extruded fire resistant border in block  1610 . An optional step may include forming a fire rated door by attaching a first decorative and a second decorative panel to the top and bottom, respectively, of the fire resistant center panel, the first stile, the second stile, the first rail and the second rail of the extruded border in block  1612 . Additional elements can be added as described in reference to  FIGS. 11-15 . Another optional step may include coating the fire resistant center panel and the extruded fire resistant border with an intumescent or fire resistant material. Note that the method  1600  can be performed as part of a continuous manufacturing process. 
     In one embodiment, a notch is formed in the first side of the fire resistant center panel, a fire resistant lock block is inserted within the notch and the fire resistant lock block is attached to the fire resistant center panel and the extruded fire resistant border, wherein the fire resistant lock block is made of the second fire resistant material. In another embodiment, the fire resistant center panel includes: (a) a first fire resistant center panel disposed between the first side and the second side proximate to the first end, wherein the first fire resistant center panel is made of the first fire resistant material; (b) a second fire resistant center panel disposed between the first side and the second side proximate to the second end, wherein the second fire resistant center panel is made of the first fire resistant material; and (c) a fire resistant insert disposed between and attached to the first fire resistant center panel and the second fire resistant center panel, and extending between and attached to the extruded fire resistant border at the first side and the second side, wherein the fire resistant material is made of the second fire resistant material. In yet another embodiment, a set of male-female connectors are formed in the extruded fire resistant border and the fire resistant center panel. The male-female connectors can be triangular-shaped, curved-shaped, rectangular-shaped, angled, tongue-and-groove, or a combination thereof. 
     In another embodiment, the first fire resistant material is extruded or molded to form the fire resistant center panel, and the second fire resistant material is extruded or molded to form the first stile, the second stile, the first rail and the second rail of the extruded fire resistant border. In yet another embodiment, the first fire resistant material is extruded or molded to form the fire resistant center panel, and the second fire resistant material is extruded or molded to form a sheet that is then gang ripped to form one or more of the first stile, the second stile, the first rail and the second rail of the extruded fire resistant border. In either embodiment the panels, stiles and rails may undergo one or more finishing steps (e.g., sanding, trimming, cutting, denibbing, etc.) so that the pieces have the proper smoothness, size and shape. 
     Furthermore, a top panel can be attached to the top of the fire resistant center panel and the extruded fire resistant border, or a bottom panel can be attached to the bottom of the fire resistant center panel, or both the top panel and the bottom panel can be attached to the fire resistant center panel. The top panel or the bottom panel can be a lignocellulosic substrate, a wood, a wood composite, a medium density fiberboard, a high density fiberboard, a particleboard, a masonite, a fiberglass, a metal, a plastic, one or more protective layers or a combination thereof. The one or more protective layers can be a fire resistant material, a blast resistant material, a ballistic resistant material, a shielding material, a chemical resistant material, a biohazard resistant material, a radiation resistant material, a dampening material, a grounding material, insulating material or a combination thereof. For example, the one or more protective layers can be one or more gypsum boards, one or more metallic sheets, one or more lead sheets, one or more Kevlar sheets, one or more ceramic sheets, a layer of urethane foam, a layer of graphite, a wire mesh or a combination thereof. 
     Referring now to  FIG. 17 , a flow chart of a method  1700  of manufacturing a door core for a fire rated door in accordance with another embodiment of the present invention is shown. An extruded fire resistant border is provided in block  1702 . The extruded fire resistant border has a central void and is manufactured by providing a first stile of the extruded fire resistant border, attaching a first rail of the extruded fire resistant border to the first stile of the extruded fire resistant border, attaching a second rail of the extruded fire resistant border to the first stile and attaching a second stile of the extruded fire resistant border to the first rail and the second rail of the extruded fire resistant border, wherein the extruded fire resistant border is made of a second fire resistant material. The void within the extruded fire resistant border is filled with a first fire resistant material that has a lower density than the second fire resistant material to form a fire resistant center panel in block  1704 . The extruded fire resistant border and first fire resistant material are baked or cured to set and fix the material in block  1706 . Sanding or other finishing steps may be performed thereafter. An optional step may include forming a fire rated door by attaching a first decorative and a second decorative panel to the top and bottom, respectively, of the extruded fire resistant border and fire resistant center panel in block  1708 . Additional elements can be added as described in reference to  FIGS. 11-15 . An optional step may include coating the fire resistant center panel and the extruded fire resistant border with an intumescent or fire resistant material. Note that the method  1700  can be performed as part of a continuous manufacturing process. 
     In one embodiment, a notch is formed in the first side of the fire resistant center panel, a fire resistant lock block is inserted within the notch and the fire resistant lock block is attached to the fire resistant center panel and the extruded fire resistant border, wherein the fire resistant lock block is made of the second fire resistant material. In another embodiment, the fire resistant center panel includes: (a) a first fire resistant center panel disposed between the first side and the second side proximate to the first end, wherein the first fire resistant center panel is made of the first fire resistant material; (b) a second fire resistant center panel disposed between the first side and the second side proximate to the second end, wherein the second fire resistant center panel is made of the first fire resistant material; and (c) a fire resistant insert disposed between and attached to the first fire resistant center panel and the second fire resistant center panel, and extending between and attached to the extruded fire resistant border at the first side and the second side, wherein the fire resistant material is made of the second fire resistant material. In yet another embodiment, a set of male-female connectors are formed in the extruded fire resistant border and the fire resistant center panel. The male-female connectors can be triangular-shaped, curved-shaped, rectangular-shaped, angled, tongue-and-groove, or a combination thereof. 
     In another embodiment, the first fire resistant material is extruded or molded to form the fire resistant center panel, and the second fire resistant material is extruded or molded to form the first stile, the second stile, the first rail and the second rail of the extruded fire resistant border. In yet another embodiment, the first fire resistant material is extruded or molded to form the fire resistant center panel, and the second fire resistant material is extruded or molded to form a sheet that is then gang ripped to form one or more of the first stile, the second stile, the first rail and the second rail of the extruded fire resistant border. 
     Furthermore, a top panel can be attached to the top of the fire resistant center panel and the extruded fire resistant border, or a bottom panel can be attached to the bottom of the fire resistant center panel, or both the top panel and the bottom panel can be attached to the fire resistant center panel. The top panel or the bottom panel can be a lignocellulosic substrate, a wood, a wood composite, a medium density fiberboard, a high density fiberboard, a particleboard, a masonite, a fiberglass, a metal, a plastic, one or more protective layers or a combination thereof. The one or more protective layers can be a fire resistant material, a blast resistant material, a ballistic resistant material, a shielding material, a chemical resistant material, a biohazard resistant material, a radiation resistant material, a dampening material, a grounding material, insulating material or a combination thereof. For example, the one or more protective layers can be one or more gypsum boards, one or more metallic sheets, one or more lead sheets, one or more Kevlar sheets, one or more ceramic sheets, a layer of urethane foam, a layer of graphite, a wire mesh or a combination thereof. 
     Now referring to  FIG. 18 , a flow chart of a method  1800  of manufacturing a fire rated door in accordance with one embodiment of the present invention is shown. A door core as shown in  FIGS. 1-10  is provided in block  1802 . A first decorative panel is attached to a top of the door core in block  1804 , and a second decorative panel is attached to a bottom of the door core in block  1806 . Additional elements can be added as described in reference to  FIGS. 11-14 . 
     Although preferred embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that various modifications can be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.