FR2617428A1 - Coating material made of wood strips impregnated with melamine resin polymerised with heating under physical pressure - Google Patents

Abstract

Coating material made of wood strips, characterised in that the said wood strips are impregnated with melamine resin polymerised with heating under physical pressure. The material in accordance with the invention is intended particularly to be employed as internal or external coating for walls of a building. It exhibits characteristics of very high resistance to physical and chemical agents while retaining the mechanical and aesthetic qualities of the wood of which it consists.

Description

 The present invention relates to a material for coating wooden slats, characterized in that said wooden slats are impregnated with melamine resin polymerized hot under physical pressure.

 We already know multiple realizations of coating materials in wood strips. These materials are, in general, intended to be fixed on a support either by mechanical means, for example nailing or screwing, or by chemical means, for example gluing carried out by the addition of an adhesive adhesive material. When using this type of coating material, it is absolutely necessary to preserve a clearance between each of the wooden blades constituting the coating in order to be able to absorb the dimensional variations which are due to the ambient humidity variations.

These dimensional variations can be more or less significant depending on the species of wood used and the clearances to be provided between the wooden blades during implementation are established according to the initial dryness of the wood and of the final use. made of it (use inside or outside of premises, for example). These precautions for use restrict the possible applications for mechanical or aesthetic reasons and require skilled labor to carry out the implementation.

 In general, this type of coating material requires, in order to maintain its mechanical and / or aesthetic qualities, additional treatment. Different types of treatments are currently known and are formulated to respond to a specific problem of use. These are essentially preservation treatments against external physicochemical agents such as, for example molds, fungi, xylophagous insects, solar radiation, etc. produced using materials such as salts, colors, varnishes, stains or paints. The types of treatment known to date have only a limited duration of effectiveness and by the same require frequent, restrictive and expensive maintenance.

Certain types of coating materials known to this
day such as, for example, mosaic floors are usual
Lely made from sawn wooden blades and come in the form of checkerboards or pre-assembled panels on or under
ports of different natures such as, for example, paper
kraft, polyethylene, thermoplastic mesh, bituminous sheets,
cork or various composite panels.
known to date, of this type of parquet are either
carried out by gluing on a support, or carried out in pose
so-called floating. Finishes are either carried out in the workshop
prior to installation, either carried out on the installation site
works and generally includes a sanding operation
followed by an application of wax, linseed oil, or even varnish.

This type of finish only provides surface protection and
must obligatorily preserve the initial clearance envisaged to absorb
the dimensional variations of the wooden slats linked to
ambient humidity variations. In addition, the different
types of surface finish known to date do not offer
sufficient resistance to chemical and physical agents
external (abrasion, humidity, dirt) and therefore
frequent maintenance or even maintenance is required
periodic total renovations.

The object of the present invention is to remedy the
disadvantages of wood plank covering materials
known and relates to a coating material of wooden strips
characterized by the fact that said wooden slats are impregnated
with hot-pressurized melamine resin
physical.

According to the characteristics of a first example
of realization of the invention, the wooden blades, preliminary
dried using known drying means, are
introduced into a sealed enclosure and subjected to a vacuum
to extract the air from the cells, then
the enclosure remaining subject to this initial depression, it
is proceeded to the introduction, inside said enclosure,
a liquid melamine resin solution that comes into contact
direct wooden slats and penetrates inside the cells
wood. This phenomenon of natural absorption of the resin solution by the wood is then supplemented by pressurizing the resin solution in order to increase its penetration inside the wood until saturation. The enclosure is brought back to atmospheric pressure and the excess resin solution is extracted from the enclosure.

Finally, the interior of the enclosure is subjected to a final vacuum in order to remove the excess solution remaining on the surface of the wood. The wooden strips are then extracted from the sealed enclosure and are then dried naturally so that only the dry extracts contained in the initial solution remain in the wood. The wooden blades, once dried, are finally clamped between the aprons of a press in order to polymerize the melamine resin contained in the wood. The polymerization cycle includes a temperature rise phase followed by a phase cooling, the physical pressure exerted on the wooden slats being maintained throughout the duration of the cycle in order to obtain a homogeneous creep of the resin on the surface of the wood and to prevent any deformation of the wooden slats by stabilizing the internal tensions which would be due to the action of temperature. In this exemplary embodiment, the press aprons are coated with a polished stainless steel sheet in order to obtain a glossy surface finish on the wooden blades.

 In a second exemplary embodiment of the invention, the wooden strips, previously impregnated with melamine resin according to the process described above, are arranged edge to edge between the aprons of the press and are made integral with each other by creep of the melamine resin during the polymerization cycle under hot pressure.

 In a third embodiment of the invention, the wooden blades used were previously obtained by mechanical slicing using a device comprising at least one metal blade having an appropriate cutting angle. During a slicing operation, the structure of the wood is always altered and the cohesion between the fibers is greatly reduced by the appearance of small cracks. This major drawback offers the advantage of favoring the penetration of the melamine resin inside the wood and the cohesion of the fibers will be restored by the creep of the resin during the hot polymerization cycle under pressure. In the same way, the small breakouts due to slicing and which appear on the surface will be hidden by the creep of the resin during the hot polymerization cycle under pressure. This offers a certain advantage because the finished product obtained thus retains mechanical qualities and aesthetic equivalent to those obtained by a conventional sawing while allowing a substantial saving of raw material.

 In a fourth exemplary embodiment of the invention, the wooden strips, previously impregnated with melamine resin according to the method described above, are arranged on a support in the form of a panel between the aprons of the press, to be secured to this same panel by creep of the melamine resin during the hot polymerization cycle under physical pressure.

This offers the advantage of allowing the fixing of the blades on a support without providing additional fixing means.
In a fifth embodiment of the invention, the wooden slats, previously impregnated with melamine resin according to the process described above, are arranged between the aprons of the press with interposition between said wooden blades and the aprons of the press at least one sheet of melamine overlay in order to increase the quality of the finish.

 In a sixth embodiment of the invention, the wooden slats, previously impregnated with melamine resin according to the process described above, are arranged between the aprons of the press so as to form a decoration such as, for example, that a mosaic parquet floor.

 In a seventh exemplary embodiment of the invention, at least one press apron is coated with an engraved material making it possible to produce a surface decoration reproduced by pressure-deformation during the hot polymerization cycle such as, for example, reconstitution natural wood pores or visible markings of joints or moldings.

In an eighth embodiment of the invention,
wooden boards, previously impregnated with melamine resin
according to the process described above, are arranged between the - aprons of the press after being coated with a sheet of
resin loaded with abrasive materials to improve
surface resistance.

Of course, the invention is not limited to examples
ples of embodiment described above, from which
may provide for other modes or other embodiments,
without thereby departing from the scope of the invention.

Such types of coverings made of wooden strips, produced
in the context of the present invention, offer numerous advantages
with respect to known coatings of the same type which are
mainly due to the use of melamine resin. The
advantages are, among others
- No moisture recovery after polymerization therefore, therefore
quent dimensional stability
- Very high wear resistance
- Very high resistance to chemical and physical agents
- Possibility of using sliced wood
- Possibility of fixing on support without addition of materials
additional
- Very high fire resistance
- Very high resistance to UV radiation

In addition, such types of materials do not require, for their
implementation, qualified personnel because they are fully
finished in the production workshop and, the very high resistance that
gives them melamine makes this implementation
much less delicate. Finally, production costs are
greatly reduced due to the possibility of using wood
sliced instead of sawn, also because of the possibilities
assembly without additional materials, because
finally that there is no need to perform a finishing operation
such as sanding, varnishing, etc.
It should also be added that such types of
materials, once implemented no longer require any
maintenance other than periodic washing.

Claims (4)

CLAIMS 7) Coating material consisting of wooden slats characterized in that the wooden slats used for making said coating material are impregnated with melamine resin.  2) coating material according to claim NO 1 characterized in that the melamine resin impregnating the wooden slats is polymerized hot under physical pressure.  3J Coating material according to any one of claims 7 and 2, characterized in that the joining of the wooden slats together is carried out by creep of the melamine resin during hot polymerization under physical pressure.  4J coating material according to any one of claims 1 to 3, characterized in that the impregnated wooden strips are covered, prior to the hot polymerization under physical pressure, with a melamine overlay.  5) coating material according to any one of claims 1 to 4, characterized in that the wooden strips are secured to any support by creep towards the support of the melamine resin contained in said wooden strips during the hot polymerization under physical pressure.  6) coating material according to any one of claims 1 to 5, characterized in that the wooden blades used were obtained by slicing.  7) coating material according to any one of claims 1 to 6, characterized in that the hot polymerization is carried out in a press whose apron located on the facing side has on its surface a material making it possible to obtain different aspects of finish such as, for example, matt, glossy or etched pores.