Method for painting planks for floors in wood and its derivatives

Abstract

 Method for painting parquet planks of wood or its derivatives or fiber-cement, comprising the following steps:
- Applying to the plank a coloured bi-dimensional vein imitating natural wood;
- Embossing a three-dimensional protruding vein;
- Optionally, applying a final top coat
characterized in that
the protruding three-dimensional vein is embossed through photo-polymerizable paint directly applied on the plank itself.

Description

[0001] The invention relates to a method for painting planks for floors (parquet) in wood or its derivatives like chipboard, plywood, MDF, HDF, etc. or fiber-cement planks. In particular, the invention relates to the possibility of giving, through the painting process, a three-dimensional texture (embossing) having, at the same time, a great mechanical resistance.

[0002] The embossing of a painted object is already known, for instance from WO9015673 General Electric and WO02068189 Canti.

[0003] In particular, WO9015673 first teaches embossing thermoplastic materials through the use of a continuous impressor belt, while WO02068189 teaches the same method using a disposable matrix web.

[0004] In the flooring industry, prefabricated planks are known, which are laid so as to simulate precious wood parquets. Such planks are made with industrial materials derived from wood (plywood, chipboard, MDF, HDF) on which a decorated sheet is glued, e. g. in melamine or paper, or similar. The surface of these decorated sheets can be smooth or veined. The veined materials tend to be more expensive.

[0005] Since the floor is intended to be walkable, the coating must provide good features of resistance to abrasion and scratch to the surface.

[0006] The main advantage of the present invention lays in the possibility of transforming planks of cheap material like plywood, chipboard, MDF, HDF or fiber-cement into planks having the aspect of much more precious and expensive materials like natural wood, adding a three-dimensional texture to already printed but smooth planks.

[0007] A second advantage comes from using paints having a high percentage of high-hardness anti-abrasion materials like aluminium oxide or corundum, which are difficult to be applied with traditional roller machines, as they wear the machines with which they are applied and are difficult to be sanded, if requested by the chosen production process.

[0008] The present invention relates to a method applying different coatings of different paints in successive steps, each having different features.

[0009] The basic method of the present invention comprises the following steps:

a. Applying to the plank a coloured bi-dimensional vein imitating natural wood;

b. Embossing a three-dimensional protruding vein;

c. Optionally, applying a final top coat.

[0010] There are provided preferred embodiments, wherein the basic method is slightly modified.

[0011] In a first preferred embodiment (Method 1), before the first step of basic method, there is an optional step of applying a base coat, transparent or of a light (white, cream) colour, and the step of printing a bi-dimensional vein.

[0012] In a second preferred embodiment (Method 2), the base coat is prepared with a coloured bi-dimensional vein, obtained by gluing a sheet, e.g. in melamine or paper, to the plank.

[0013] The invention will be now described with reference to the three tables of drawings which illustrates non limiting embodiments, in which:

• Figure 1 is a flow chart describing the basic version of the method;
• Figure 2 is a flow chart describing a first alternative version of the basic method (Method 1);
• Figure 3 is a flow chart describing a second alternative version of the basic method (Method 2).

[0014] In Figure 1 the flow chart describes the steps of the Base method:

a. Applying to a plank a coloured, bi-dimensional vein, imitating natural wood The preparation of the coloured, bi-dimensional, vein simulating natural wood can be performed in different ways according to the chosen method, and will be described in detail in the description of Method 1 and Method 2.

b. Embossing a three-dimensional vein
The embossing of a protruding three-dimensional vein occurs applying photo-polymerizable paint, e.g. through rollers or sprayed, which is uniformed by the belt/web matrix bearing the texture to be transferred on the plank. Said paint is dried or gelled by the U.V. lamp above the impressor belt/web matrix. The U.V. radiation crosses the belt/web matrix itself, starting the reaction of the photo-polymerizable paint. The photo-polymerizable paint, containing agents like aluminium oxide or corundum, aimed to increase the superficial hardness and the abrasion-resistance, takes the desired texture through the transferring of the imprint on the belt/web matrix, and the successive polymerization before removal of the belt/web matrix itself. The impressor can be a disposable web matrix or a closed continuous belt.

c. Optionally applying a transparent top coat
The application of a transparent top coat aims to uniform the degree of gloss of the plank and to increase the layer of applied paint. Preferably, it is applied with a roller. The transparent top coat can be glossy or matt. The top coat, too, preferably contains substances making the surface abrasion-resistant, e.g. aluminium oxide or corundum. The transparent top coat, applied with rollers, is deposited on the protruding parts, which are more prone to wear.

[0015] Figure 2 is a flow chart representing Method 1 steps. The unvaried steps of Method 1 are written in bold.

[0016] Method 1 comprises the following steps:

a. Optionally preparing a base coat of a transparent or light (white, cream) colour The light (white, cream) base coat has the aim of providing a base allowing a good quality printing, and at the same time covers the basic structure of the plank (e.g. the particles of chipboard). The paint is typically applied with a roller.

b. Digital or contact printing of the vein or of the desired effect The printing applied on the texture allows to get a more natural effect, similar to that of natural wood. The printing techniques typically used are digital printing or contact printing through engraved rollers. The inks used can be water inks, solvent inks, or U.V. photo-polymerizable inks.

c. Embossing a three-dimensional protruding vein

d. Optionally applying a transparent top coat.

[0017] Method 2 comprises the following steps:

a. Using a decorated sheet printed so as to simulate natural wood
The plank is coated with a printed material, e.g. paper or melamine or similar, reproducing a bi-dimensional coloured vein, but its surface is smooth, and therefore the effect is not natural. Before embossing a three-dimensional protruding vein, it might be necessary to apply a primer layer allowing a better adhesion of the paint embossing the three-dimensional protruding vein.

b. Embossing a three-dimensional protruding vein

c. Optionally applying a transparent top coat.

[0018] The choice of Method 1 or 2 depends on the decision of starting from a raw material or from an coated material. Method 1, with digital printing, is more expensive, but it allows to imitate a wider number of natural veins.

[0019] In Method 1, the choice of using as base coat a matt lacquer before applying the three-dimensional veins allows to get a more uniform background colour. This method is preferably used when the material to be painted is particularly coarse (chipboard) or when the final colour of the painted object is light (for instance when birch vein has to be simulated), while transparent lacquer is used when the background colour of the raw material is already suitable for the expected final result or has a vein that is to be kept visible after the process.

[0020] The application of a transparent top coat, although optional, allows to apply the hardening component in two layers, one during the application of the three-dimensional vein, and one as top coat. The presence of a double layer of hardening component further enhances abrasion-resistance and scratch-resistance of the finished plank.

Claims

1. A method for painting parquet planks of wood or its derivatives or fiber-cement, comprising the following steps:

a. Applying to the plank a coloured bi-dimensional vein imitating natural wood;

b. Embossing a three-dimensional protruding vein;

c. Optionally, applying a final top coat

characterized in that
the protruding three-dimensional vein is embossed through photo-polymerizable paint directly applied on the plank itself.

2. The method according to claim 1, wherein the protruding three-dimensional vein is applied through water or solvent photo-polymerizable paints, and contains agents enhancing the abrasion-resistance of the surface.

3. The method according to claim 1 or 2, wherein the transparent top coat is applied through water, solvent or photo-polymerizable paints, and can contain agents enhancing the abrasion-resistance of the surface.

4. The method according to claim 1 to 3, comprising, before the step of applying a transparent three-dimensional vein to the plank, a step of preparing a bidimensional vein on the light base performed through digital printing or contact printing.

5. The method according to claim 4, comprising, before the printing step, a step of preparing a base of transparent or white or light colour on which printing is performed.

6. The method according to claims 1-3, wherein the coloured bi-dimensional vein is obtained through a sheet of melamine, paper or similar, pre-glued on the plank itself.

7. The method according to one of claims 1-3, wherein the application of the three-dimensional vein through a transparent photo-polymerizable paint is performed through transfer of the imprint on an impressor belt/web matrix and successive polymerization before removal of the impressor itself; the impressor can be a disposable web matrix or a continuous belt.

8. The method according to claim 4, wherein colour printing is performed through digital printing or contact printing by engraved rollers, and the inks can be water, solvent, or U.V. photo-polymerizable inks.

9. The method according to claim 5, wherein the base of transparent, white or light colour is applied with a roller, and can be applied with a water paint, solvent paint, photo-polymerizable paint or water ink, solvent ink, or photo-polymerizable ink.

Drawing