IL106920A - Coated plywood boards and method of producing same - Google Patents

Description

D*ii-< i7 o>Qinn ο *τ !ΐί7 Jiim!7 COATED PLYWOOD BOARDS AND METHOD OF PRODUCING SAME COATED PLYWOOD BOARDS AND METHOD OF PRODUCING SAME FIELD OF THE INVENTION The present invention relates to the production of woodwork boards, particularly of the type used in the furniture industry.

BACKGROUND OF THE INVENTION In the furniture industry there are mainly used two categories of woodwork boards . In one category there are included plywood boards with a coating of a thermosetting material, mostly melamine resin based laminae (known as "FORMICA" ( TM ) ) , which can be of a variety of colors, surface patterns, thickness, etc., as required both for the protection and the esthetic appearance of the boards .

The other category of boards include a core of compacted woodchips which are then coated with the melamine resin based laminae.

. There is however a basic difference between the manufacturing processes of these two categories.

Regarding the conventional, mass-production process, it has been axiomatically accepted that the coating with melamine layer is only applicable to the compact i woodchips boards, whereas the application of the laminae on plyboard cores could only be effected by a non mass production industrial manner, namely in a "cold process" rather than a heat-press process.

In more detail, the heat-press process involves the use of heavy presses, of over 20 tons and a temperature of between 160 - 200 degrees. The lamina itself may be in the form of thin, paper-like sheets (of about 100-160gr/sq.m) which are impregnated with the resinous material and with a glue component which is used for the attaching thereof on top of the woodchips board.

Should the coating be of a greater thickness, Formica boards are used, which are essentially an array of melamine paper applied to a base substrate and compacted together by a separate heat-pressing process.

, It has been found that if a plyboard core board is required for a given purpose, the application of the melamine or Formica coating by the conventional heat- i pressing process is impractical. This is due to the fact that during the heat-pressing stage, a certain quantity of vapors and/or steam of both the glue compound and the inherent relatively high water contents of the plywood is inevitably developed. Since the vapor cannot escape during the pressing stage, the result is in the form of bubbles trapped under the lamina, which appear as shallow swellings affecting both the aesthetic and utilization i functions of the board. i f It has been thus conventionally accepted that if one wishes to use plywood boards with a resinous material 1 ί coating, it can be only prepared by a "cold", gluing process, namely' not on an industrial, mass production scale .

It should be noted in this context that plywood core boards are regarded preferable to woodchips boards , particularly in the respect that they are light-weight more durable, flexible, and more readily applicable to other working processes such as the driving of woodscrews or nails and/or uses such as large-size doors. i ' It is therefore the prime object of the present invention to provide plywood core boards coated by melamine or Formica laminae and method of producing same by a conventional industrial heat-press process.

SUMMARY OF THE INVENTION Thus provided according to one aspect of the present invention is a woodwork board comprising a core of plywood, a ply of a porous material applied to at least i one side of the core, and a coating of a thermosetting material lamina applied to the said ply.

The porous material ply, and the lamina, are usually provided at both sides of the plywood board.

The porous material is preferably of the type known as Medium Density Fiberboard (MDF) which is well known by itself and used in the woodwork products industry. t According to another aspect of the invention there is provided a method of producing woodwork boards comprising the steps of preparing a plywood board, applying to at least one side of the plywood board a ply of a porous material, and applying a thermosetting material lamina to the said ply by a heat-press gluing process.

BRIEF DESCRIPTION OF THE DRAWINGS j These and further features of the invention will be t hereinafter described by way of example only, with reference to the accompanying drawings, wherein - i Fig. 1 is a schematic representation of a board prepared according to a preferred embodiment of the present invention; and Fig. 2a to 2c schematically illustrate stages of producing the board of Fig. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT i i In Fig. 1 there is shown a portion of a board, generally denoted A, which can be of any size, produced according to the teachings of the invention. The board A comprises a core generally denoted B of a conventional plywood, namely an array of veneers press-glued to each other, preferably of an odd number and in crossing fiber directions, as conventionally known.

Now, according to the present invention one or two plies C of conventional MDF material, or any other material satisfying the requirements as already above mentioned, are applied to the plywood core B, e.g. by a conventional heat-press process. The thickness of the MDF plies are typically between 2 and 3 mm.

Finally, i melamine laminae D are applied to the outer surface of plies C.

As already mentioned, the MDF or other porous \ material plies C are responsible for absorbing the steam I generated by the plywood due to its inherent humidity, and also of the vapors which are generated by heating the glue and the resinous material impregnated in the melamine lamijia D and, the outcome is the same as if the melamine lamina has been applied to a core of compact woodchips conventional boards . The same process may be applied, with the necessary adaptations, to the application of Formica plates to produce coated plywood c Iore boards . ί Turning now briefly to Figs. 2a-2c, there are shown the stages of producing the board A. Hence, the plywood board B (separately produced), and two plies of the porous material C are placed into a heat-press schematically shown as plates El and E2. Obviously, the array of the veneers B and the plies C — preferably of MDF as explained — may easily be produced in one and the same stage by, the conventional process at the woodwork plant. After the application of the plies C to the board B (Fig. 2a) -- if not already incorporated, the stage of i I Fig. 2b is applied, namely the gluing of the melamine laminae D to the plies C - again by a conventional heat-press process,.

The finished board A is again shown in cross-section Fig. 2c.

The method and board according to the invention are therefore fabricated in a straightforward, conventional manner which is advantageous in the sense that it does hot require any interference with or modifications of the i conventional woodwork production plant equipment. i Therefore the present invention opens the way for using plywood based boards for applications hitherto confined only' to more expensive boards, namely finished by non-industrial processes.

Those skilled in the art will readily appreciate that various changes, modifications and variations may be j applied to the invention as hereinbefore exemplified without departing from the scope of the invention as I defined in and by the appended claims.

Claims (1)

1. WHAT IS CLAIMED IS: j. A woodwork board comprising a core of plywood, a ply of a porous material applied to at least one side of the core', and a coating of a thermosetting material lamina applied to the said ply. The board of Claim 1 comprising said ply and lamina at both sides of the plywood core. The board of Claim 2 wherein the said porous material is air permeable. The board of Claim 3 wherein the said porous material is of the type known as Medium Density Fiberboard (MDF) . The board of Claim 4 wherein the said plies are applied to the said core by a heat-press gluing process . : 6. The board of Claim 4 wherein the said laminae are 1 4 applied to the MDF ply by a heat-press gluing i ί process.. ί ! 7. The board of Claim 1 wherein the thermosetting ί lamina is of melamine resin. 8. The board of Claim 7 wherein the lamina is in the form of melamine resin impregnated paper-like sheet. 9. The board of Claim 7 wherein a lamina is in the form of laminated plate ("Formica" TM) . . J 10. A method of producing woodwork boards comprising the steps of: ! (i) preparing a plywood board; applying to at least one side of the plywood board a ply of a porous material ; and (iii) applying a thermosetting material lamina the said ply by a heat-press gluing proc The method of Claim 10 wherein the said porous material' ply and said lamina are applied to both sides of the plywood board. 12. The method of Claim 11 wherein the said porous material ; ply and said lamina are applied by conventional heat-press process. The method of Claim 10 wherein the said porous material ply is made of Medium Density Fiberboard i (MDF). 14. The method of Claim 10 wherein the said lamina is made of melamine resin. 15. The method of claim 10 wherein steps (i) and (ii) ! are performed by one and the same operation. 16. A woodwork board substantially as hereinbefore described and with reference to the accompanying 1 J drawings . 17. A method' of producing woodwork boards substantially as hereinbefore described with reference to the accompanying drawings . For the Applicant 24187.wps