Method of manufacturing a molded door skin from a flat wood composite, door skin produced therefrom, and door manufactured therewith

Abstract

A method of manufacturing a hollow core door is disclosed, as wall as a corresponding hollow core door. The method includes the steps of providing a solid flat door skin, moisturizing the flat skin, applying a conditioning resin thereto, pre-heating the flat door skin, and thereafter pressing the flat door skin between a pair of heated platens in a press in order to reform the flat skin into a molded skin including a plurality of panels defined therein. The press continuously closes in order to reform the flat skin into the molded skin, with the rate of press closure being a function of the determined hardness of the flat skin to be reformed. The resulting door skins have an improved bond strength, and are efficiently manufactured.

1 . A method of manufacturing a hollow core door, the method comprising the steps of:
 providing a solid wood composite flat blank having a density of at least about 550 kg/mm 3 ;   moisturizing the flat blank to raise its moisture content;   applying a liquid conditioning thermal curable resin to at least one major surface of the flat blank;   pre-heating at least a surface of the flat blank to a temperature of at least about 80° C.;   after said pre-heating step has been performed, positioning the flat blank into a press between first and second platens, at least one of the platens being heated;   reforming the flat blank into a molded door skin including a plurality of panels defined therein by closing the press; and   affixing at least a first molded door skin to a first side of a door frame and affixing a door skin to an opposite second side of the door frame.   
     
     
         2 . The method of  claim 1 , wherein the density of the flat blank, prior to said pressing step, is from about 550 to 120 kg/m 3 . 
     
     
         3 . The method of  claim 1 , wherein the bond strength of the flat blank prior to said pressing step is less than about 2.0 N/m 2 , and wherein the bond strength of the molded door skin after said pressing step is at least about 2.0 N/mm 2  so that said pressing step in combination with at least said applying a conditioning resin step increases the bond strength of the skin. 
     
     
         4 . The method of  claim 1 , wherein said pressing step closes the press at a rate at least about 0.25 mm per second. 
     
     
         5 . The method of  claim 1 , further comprising the steps of:
 determining at least one of the following parameters of the blank, the hardness, density, density profile, depth of molding, and percentage binder or resin content of the flat blank; and   closing the press at a predetermined closing rate, that in advance is determined by and is a function of the determined parameter of the flat blank.   
     
     
         6 . The method of  claim 1 , wherein in said closing step, pressure applied in closing the press is uninterruptedly increased until the press reaches a closed position where the blank therein is in the form of the molded door skin having the plurality of panels defined therein. 
     
     
         7 . The method of  claim 1 , further including the step of applying a pigmented sealer to the flat blank prior to said pressing step. 
     
     
         8 . The method of  claim 7 , applying the sealer to the flat blank in an amount from about 4-10 g/m 2 . 
     
     
         9 . The method of  claim 1 , wherein said applying a conditioning resin step is performed so as to apply the resin to a surface of the flat blank in an amount of from about 20-200 gm/m 2 . 
     
     
         10 . The method of  claim 1 , wherein said steps are performed in the order in which they are recited. 
     
     
         11 . The method of  claim 1 , wherein the molded door skin has a bond strength of at least about 2.5 N/mm 2 . 
     
     
         12 . The method of  claim 1 , wherein the resin applied to the flat blank in said applying step includes one of urea formaldehyde resin and melamine formaldehyde resin. 
     
     
         13 . The method of  claim 1 , wherein said pre-heating step is performed prior to said moisturizing step. 
     
     
         14 . The method of  claim 1 , further including the step of positioning the flat blank in a pre-press area prior to said pressing step, and while the flat blank is in the pre-press area performing said pre-heating step and simultaneously applying a moisturizer to the flat blank. 
     
     
         15 . The method of  claim 1 , wherein in said pressing step the first platen remains stationary and the second platen is urged toward the first platen in order to reform the blank positioned in the press. 
     
     
         16 . The method of  claim 1 , wherein the molded door skin a substantially constant density of from about 800-1,200 kg/m 3 , and wherein the density of the molded door blank is higher than the density of the flat blank from which it is formed. 
     
     
         17 . (canceled) 
     
     
         18 . A hollow core door comprising:
 a door frame;   first and second door skins attached to said door frame so as to define a hollow core area there between, at least one of said skins being a molded door skin   said one molded door skin having molded therein a plurality of panels; and wherein same one molded door skin has a bond strength of at least 2.0 N/mm 2      
     
     
         19 . The door of  claim 18 , wherein each of the first and second door skins is a molded door skin having a bond strength of at least 2.5 N/mm 2    
     
     
         20 . The door of  claim 18 , wherein each of said first and second door skins is a molded door skin formed by pressing a loose bat or mat into a flat door blank having a density of at least about 550 kg/m 3 , and thereafter moisturizing, heating, and reforming in a press said flat door blank into a molded door skin having the panels molded therein, so that the bond strength of each of the skins is increased relative to that of the original flat blanks from which they are formed. 
     
     
         21 . A method of making a molded door skin, the method comprising the steps of:
 providing a flat solid wood composite blank having a density of at least about 550 kg/m 3 ;   applying liquid thermal actuatable resin to the flat blank;   positioning the flat blank in a press having first and second platens;   heating the first and second platens each to a temperature of at least about 320-425° F.;   closing the press at a predetermined closure rate so as to reform the flat blank into a door skin including a plurality of panels molded therein; and   allowing the resin in the reformed door skin to cure for thereby forming a molded door skin.   
     
     
         22 . (canceled)