Stock material or miscellaneous articles – Structurally defined web or sheet – Continuous and nonuniform or irregular surface on layer or...
Reexamination Certificate
1999-02-03
2002-01-01
Cole, Elizabeth M. (Department: 1771)
Stock material or miscellaneous articles
Structurally defined web or sheet
Continuous and nonuniform or irregular surface on layer or...
C428S151000, C428S213000, C428S220000
Reexamination Certificate
active
06335082
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a reformed medium density fiber (MDF) board product, such as a door skin, and a process for reforming an MDF board to provide such a product.
There are several known techniques for manufacturing composite, hollow-core doors with ornamental features such as simulated panels and simulated wood grain. Some of these techniques involve the molding of MDF boards to create door skins. Such door skins are subsequently finished using primers, pigments, and the like, to provide a finished door skin. The finished door skins then are secured to opposing sides of a support frame to define a hollow-core door.
While such conventional techniques can provide fairly realistic simulations of paneled wood doors, they typically involve the use of a purchased door skin that is relatively expensive because it is produced through use of a complicated capital-intensive molding process. Masonite Corporation, for example, produces molded door skins by pressing a relatively thick fiber matt into a door skin having the requisite panels. The molded door skin provides contouring at depths close to or matching the depth typically found in an actual paneled door. The molds which provide such contouring, how ever, are complex and very expensive. Such molding processes also require an excessive amount of time and energy. As a result, the conventional simulated panel wood doors are rather expensive. Typically, they are too expensive for use in low-cost housing projects and the manufactured home industry. Since most buildings have multiple doors, the expense associated with providing conventional simulated paneled doors in a particular building is multiplied by the number of doors in that building. As a result, the aesthetic benefits derived from simulated paneled wood doors are seldom enjoyed by purchasers or occupants of low-cost housing, office trailers, manufactured buildings, and the like.
There is consequently a need in the art for a process of manufacturing a door skin with ornamental features, such as simulated wood panels and simulated wood grain texturing, using relatively simple, quick, and inexpensive molding techniques and equipment.
There is also a need for a process of molding flat MDF boards after finishing, without damaging the coating(s) on the finished product or cracking the MDF board and/or the fibers contained therein. Certain conveniences and manufacturing efficiencies could be realized if flat MDF boards could be finished prior to molding. This, for example, would allow the finishing coats to be applied using roll coating and other application techniques, which are best suited for use on flat surfaces. In addition, it would permit the stocking of finished flat MDF boards in inventory, and the molding of such flat boards after orders are received without having to carry out a subsequent finishing process.
There have been efforts in the prior art to deform flat MDF board, but those efforts have not yet produced a commercially suitable product. The efforts frequently result in a commercially unsuitable surface due to breaking of the fiber in the board, thus providing a surface that is not suitable for being finished. No efforts to deform a “finished” MDF board are known.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to overcome the problems associated with conventional molding techniques by providing, among other things, a process for reforming a pre-finished medium density fiber (MDF) board having at least one pre-finished surface which carries at least one coating.
Another object of the present invention is to provide a process of manufacturing a door skin with ornamental features, such as simulated wood panels and simulated wood grain texturing, using relatively simple, quick, and inexpensive molding techniques and equipment.
Yet another object of the present invention is to provide a process of molding flat MDF boards after finishing, without damaging the coating(s) on the finished product or cracking the MDF board and/or the fibers contained therein.
Still another object of the present invention is to provide a medium density fiber (MDF) board product comprising a pre-finished medium density fiber (MDF) board having at least one pre-finished surface which carries at least one coating, wherein the pre-finished surface(s) and the coating(s) are press-molded to provide a relief feature after application of the coating(s).
To achieve these and other objects, the present invention provides a process for reforming a planar pre-finished medium density fiber (MDF) board having at least one prefinished surface which carries at least one coating. The process comprises the steps of placing the planar pre-finished medium density fiber board in a heated press mold; closing the heated press mold while the pre-finished medium density fiber board is located therein; applying pressure and heat to the pre-finished medium density fiber board using the heated press mold so that the pre-finished surface(s) is (are) reformed without cracking, bubbling, or removal of the coating(s); opening the heated press mold; and removing the pre-finished medium density fiber board from the heated press mold.
The present invention also provides a medium density fiber (MDF) board product comprising a pre-finished medium density fiber (MDF) board having at least one pre-finished surface which carries at least one coating. The pre-finished surface(s) and coating(s) on the board are press-molded to provide a reformed feature therein after application of the coating(s).
Also provided by the present invention is a process for making a pre-finished medium density fiber (MDF) board which is reformable after finishing, the process comprises the steps of applying at least one pigment layer to at least one major surface of a planar raw medium density fiber board, and applying at least one polymer top layer over the pigment layer(s). The polymer top layer(s) has (have) a release agent which prevents the polymer top layer(s) from adhering to the heated press mold during press molding. The pigment layer(s) and polymer top layer(s) are applied using materials and thicknesses thereof which are capable of withstanding press-molding at temperatures and pressures sufficient to reform the pigment layer(s) and the polymer layer(s), without cracking, bubbling, and adherence to a press mold.
The above and other objects and advantages will become more readily apparent when reference is made to the following description taken in conjunction with the accompanying drawings.
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PCT International Search Report, Appl. No. PCT/US00/02775, filed Mar. 2, 2000.
Cole Elizabeth M.
Liniak, Berenato, Longacre & White L
MDF Inc.
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