IT202100020429A1 - Primer applicable to a wood composite product and coating method and machine of such a product - Google Patents

Description

Primer applicable to a product in composite material derived from wood and method and machine of

coating of such a product

Primer applicable to a wood composite material product and coating method and machine of such a product

DESCRIPTION

Field of invention

The present invention relates to the sector of covering or decorating products in wood-derived composite material, especially MDF panels.

Pi? specifically, the present invention refers to a primer that can be applied to a product made of wood-derived composite material, such as an engineered wood panel, which allows such a product to be coated or decorated with powder paint.

The present invention also relates to a method and machine for coating such a product.

State of art

In the building sector, products are often used, especially in the form of panels, in composite material derived from wood, i.e. panels made by joining wood-derived chips, particles, fibers or flours using a special adhesive compound.

These panels are also known as engineered wood panels precisely because they are engineered wood panels. they are the result of a process which consists in gluing together wooden particles to form a composite material.

Among the most Well-known engineered wood panels include medium-density fiberboard (MDF), low-density fiberboard (LDF), and high-density fiberboard (HDF).

These panels differ in the density? of the material that composes them. For example, LDF panels have a density? of about 550-650 Kg/m<3>, the MDF panels have a density? of about 650-800 Kg/m<3 >and the HDF panels have a density? of about 800-1050 Kg/m<3>.

Compared to non-engineered wood panels (solid wood), i.e. solid or solid wood, engineered wood panels have many advantages. For example, they can be made with the specific characteristics requested by the customer according to the particular application of the panel, and are more? easy, quick and inexpensive to make compared to non-engineered wood panels.

In particular, MDF panels are used to make home furnishings or workplaces, i.e. to make shelving, furniture, doors, tables, or to cover the walls, precisely because they are made of wood. can be made in order to have a structure as pi? uniform as possible, with adequate thermal and acoustic insulation and with significant impact resistance. In addition, engineered wood panels are recyclable and environmentally friendly.

In general, engineered wood panels have for? the disadvantage of being aesthetically unappealing why? they have a brownish color and surfaces with uneven textures, due to the wood-derived composite material of which they are made. For similar reasons, these panels are also not very pleasant to the touch (a non-negligible aspect precisely because of their use in the home or at work).

For this reason, after being made, engineered wood panels are often coated or decorated, in order to cover up the staining and irregularities in the structure. of the surface.

For example, engineered wood panels are coated or decorated by liquid painting or by lamination, which consists of gluing a decorated laminate onto the panel.

These engineered wood paneling methods present for? of the drawbacks.

In particular, liquid painting is not very environmentally sustainable because? ? associated with a high release of VOCs (Volatile Organic Compounds) during the paint evaporation phase. This ? due to the fact that liquid paints are made up of up to 70% organic solvents.

Furthermore, the use of liquid paints does not allow the reuse of the paint fraction which, during the application phase, does not remain adhered to the panel. In practice, about 50% of the liquid paint used does not adhere to the panel and cannot? be reused (or in any case if it can be reused this does not happen in a simple, cheap and fast way).

The disposal of the paint itself is not very environmentally sustainable, why? provides for the emulsion of the liquid paint in water and a decantation of the emulsion in special tanks.

Overall, therefore, in addition to being not very sustainable, the use of liquid paint is? also not cheap.

This aspect ? also linked to the need, given the high production of VOCs, to carry out the liquid painting in environments equipped with special air extraction systems, specially specialized technical personnel and precise fire prevention protocols. The method of coating with liquid paint also involves various cycles of applying the paint and sanding done by hand. These cycles make this method of coating or decoration expensive and inefficient.

Finally, liquid painting does not allow you to coat the panels with a homogeneous layer of paint or even to create elaborate and good quality decorations in an easy, simple and fast way.

In particular, at the edges, a suitable application of liquid paint must be carried out with a relative edging operation. In other words, liquid painting does not allow you to coat a panel, including the edges, in a single application, but provides for more? applications in separate portions of the panel.

As for the lamination, however,? to be noted that this method can? not give satisfactory results because?, over time, the decorative layer can? detach from the product, especially at the edges.

In the light of what has been described above, it is therefore clear that to date there are no products and methods for coating, or decorating, a panel made of wood-derived composite material in a simple, fast, effective, economical and eco-sustainable way.

In an attempt to solve the limitation of the solutions mentioned above, various attempts have been made to coat panels in wood-based composite material using alternative methods, for example using powder paint.

These attempts have not led to effective results, or have led to unsatisfactory results in terms of thickness of the paint layer and durability of the paint, essentially because? the mechanism of adhesion of the powder coating to the substrate ? electrostatic type.

In practice, the powder paint, electrostatically charged by means of a special gun, remains adhered to the substrate to be coated only if the substrate has an electrostatic charge of the opposite sign to that of the powder paint.

As known, metallic substrates are per se? electrostatically charged, and therefore already? they are extensively painted using powder paint.

Instead, the panels in composite material derived from wood, due to the properties? same as the material, they cannot be electrostatically charged to a level that allows adequate adhesion of the powder paint and forms a layer of paint of at least?80?m?

Furthermore, taking into consideration the traditional method of powder coating of metals, it appears that the polymerization of the powder paint on the metal substrates is ? induced by heating the product, with the powder paint adhered, to a temperature of at least 130°C for about three minutes in an air oven.

In practice, to powder coat a substrate, ? Is it necessary to heat it to a temperature of at least 130? for several minutes after you ? applied on it the powder paint. This circumstance represents a further limitation for the technician in the sector in trying to powder coat a panel in wood-based composite material, and a further cause, in addition to that linked to the properties? electrostatics, of the absence of methods that allow these panels to be powder coated.

In fact, as known, if heated, the water and other substances contained in the wood-derived composite material of which the panels are made begin to heat up and evaporate. As they evaporate, they exert pressure towards the outside of the panel and cause cracks in the panel itself and in any layer of powder paint that remains adhered.

Therefore, even if it were possible to get the powder paint to adhere to a panel made of composite material derived from wood, it would be necessary to deal with the possible breakage of the panel caused by the heating foreseen in the polymerization process itself.

Have you seen the technical problems listed above? clear because, to date, there are no adequate solutions that allow you to powder coat a panel in composite material derived from wood.

Summary of the invention

Purpose of the present invention? that of providing a primer that allows a panel made of wood-based composite material to be coated or decorated in a simple, fast, effective, economical and eco-sustainable way.

? It is also an object of the present invention to provide a primer which allows to overcome the limits of the prior art and to powder paint a product in wood-derived composite material on which the primer is applied. applied.

For the purposes of the present invention, by product made of wood-derived composite material we mean any product made of engineered wood, ie made by gluing together slabs or wooden particles to form a composite material.

In particular, for products in wood-derived composite material, it is possible to mean a fiberboard/fibreboard composite product, such as medium-density fiberboard (MDF), or low-density fiberboard (LDF), or high-density fiberboard (HDF), or a chipboard, or an OSB (Oriented Strand Board) or plywood product.

For the purposes of the present invention it is not the product must have a particular shape or size; in fact, the product can? be flat, curved, wavy or pu? be made as a panel or as a beam.

In a first aspect thereof, the present invention therefore relates to a primer according to claim 1.

In particular the claim 1 ? directed to a primer applicable to a wood composite material product comprising a resin matrix, a matrix solvent and a substance selected from metal oxides or metal-silicates, or a mixture thereof.

In practice, the primer according to the present invention can comprise metal oxides or metal silicates or a mixture of metal oxides and metal silicates.

The primer allows you to powder coat a product in wood or its derivatives, hereinafter identified only as a ?product?.

In fact, the metal oxides and/or metal-silicates primarily have the function of creating an electrostatically charged layer on the surface of the product and allowing the powder paint to adhere; secondly, the metal oxides and/or metal-silicates make it possible to reflect part, or all, of the radiations used in the polymerization process of the paint, so that there is no excessive heating of the product, especially inside it.

In other words, by reflecting radiation, the metal oxides and/or metallosilicates slow down the overheating process of the product and limit the evaporation of the water or other substances inside it, or the migration of humidity towards the panel surface.

In this way it is avoided that, during the polymerization process of the powder paint, breakages occur in the product and in the layer of paint itself due to the outward thrust exerted by water vapor or other substances.

Basically, the primer described here allows the limitations encountered in the prior art to be overcome which until now prevented satisfactory results from being obtained in the painting of products made of wood-derived composite material.

In this way, ? It is possible to coat or decorate these products, obtaining the advantages given by the powder coating listed below.

First of all, does powder coating offer advantages from the point of view of sustainability? environmental why? allows, compared to liquid painting, to eliminate the use of solvents and VOC emissions. Furthermore, the use of powder coating is not ? associated with disposal problems because, unlike liquid paint, powder paint does not have to be emulsified in water to be disposed of.

Furthermore, the powder coating does not provide for the need? to carry out intermediate sanding, i.e. to perform more? applications and smoothing by hand between one application and the next.

This aspect is particularly advantageous because? allows to reduce the handling of the panels, to be able to reserve a smaller space than the processing place for the coating of the products (it is not necessary to set up a special area for sanding) and to preserve the health of the workers because, in the absence of sanding, no fine dust is formed which could be inhaled by them.

Furthermore, the use of powder coating reduces the risk of fire, so much so that the systems in which powder coatings are applied are not subject to specific regulations such as those relating to flammable liquids.

In general, equal? conditions, the time required to carry out a powder coating is 50% less than the time required to paint a product with liquid, and it is ? required less energy use.

The powder coating guarantees a quality top of the decoration and allows you to correct any errors in the painting process because, using an air gun, it is powder coating applied to the product can be removed.

The powder coating? associated with waste that reaches a maximum of 5% of the powder paint used and allows you to obtain a homogeneous layer on the product thanks to the properties? self-leveling powder paint.

Finally, operationally speaking, powder coating systems require less maintenance, are associated with lower operating costs and do not require particularly specialized operators.

Thanks to the properties reflective of metal oxides and/or metal-silicates ? It is also possible to limit or eliminate the number of products rejected due to damage caused by heating in the curing stage of the powder coating.

The present primer ? also able itself to confer a defined chromatic characteristic to the product, i.e. to give a uniform color to the product, preferably white, and to make the product pleasant to the touch, smooth and uniform.

Basically, applying the primer to the product also decorates the product itself, covering the color of the wood-derived composite material, and making it more durable. uniform the surface to be powder coated. For example, the primer can? give the product a white color, making it more? simple to later paint the product with other colors if desired.

In essence, the product to which ? when applied, the primer according to the present invention appears of a uniform color (preferably white) and with a uniform coating and/or decorative layer also at the edges.

Preferably the primer layer on the product ? of at least 10pm, and preferably between 10?m and 30?m.

Preferably the metal oxides and/or metal silicates are present in the primer at 20-45% by weight.

Preferably the metal oxides and/or metal silicates have properties IR reflective, i.e. have the ability? to reflect infrared radiation. In particular preferably the metal oxides and/or metal-silicates can reflect infrared radiations with a wavelength between 2?m and 10?m.

In particular, the product coated with the primer preferably has a coefficient of reflection of IR rays of at least 0.10, and more? preferably between 0.10 and 0.31. In other words, preferably the product coated with the primer allows to reflect at least 10% of the IR rays incident on the product and, more? preferably it allows to reflect from 10% to 31% of the IR rays incident on the product. The reflection coefficient pu? be estimated using the method described below with reference to test III.

Preferably resin? at 30-40% by weight.

Preferably the resin matrix ? a polyester resin or an acrylic resin.

Preferably the metal oxides and/or metal silicates have properties electrostatic or are electrostatically chargeable. In practice, coating the product with the primer? It is possible to electrostatically charge the product itself and cause any subsequently applied powder paint to adhere to the product.

In essence, a primer with properties is described here? Reflective and electrostatic IR.

Preferably the solvent used in the primer ? waterfall.

Preferably the metal oxides are selected from titanium oxide or aluminum oxide, or are a mixture of titanium oxide and aluminum oxide.

Preferably these metal oxides are initially dispersed in the resin matrix.

Preferably the titanium oxides are a mixture of 9-11% by weight titanium oxide and 14-18% by weight aluminum oxide.

Preferably the primer comprising an amine-based crosslinking agent which promotes crosslinking of the resin matrix and/or a surfactant/dispersant and/or a rheological/leveling agent to improve viscosity. of the primer and allow its application by spraying on a product.

In one embodiment the primer can include an allotropic form of electrostatically charged graphite or that can? be electrostatically charged. This feature can contribute to electrostatically charge the product to which the primer ? applied, to favor a possible subsequent powder coating.

Preferably the allotropic form of graphite ? present at 1% by weight in the primer.

In addition or as an alternative to the allotropic form of graphite, the primer can? also include ions of a dissolved salt in order to electrostatically charge the product. For example ? possible to dissolve NaCl sodium chloride in the primer.

In one embodiment, the primer ? composed exclusively, except for impurities, of a resin matrix, a solvent and metal oxides and/or metal-silicates. In other embodiments, additives may be present.

The present invention also relates to a method for coating a product made of wood or its derivatives, according to claim 16.

In particular, the method includes the phases of:

a) make available a wood product in its derivatives; b) apply to said product a primer with properties? reflective and electrostatic IR;

c) heating the product to solidify the primer applied during step b).

In other words, in the method described herein a primer with the characteristics described above is preferably applied.

The present method allows, firstly, to coat a product with the primer described above and, secondly, to powder coat the product on which it is applied. applied the primer.

In other words, the method makes it possible to create a base on which to carry out a powder coating of a product in wood-derived composite material.

The present method preferably comprises one or more? of the features, or steps, described in claims 17-26.

In particular, before phase b) the product can? be heated to a temperature between 50°C and 80°C for 1-2 minutes, and then possibly cooled, to reduce, or eliminate, the water content present in the product, preferably below 5% by weight. The temperature and the duration of the treatment are chosen according to the dimensions of the panel 1, the material of which ? compound and water content.

Preferably ? It is also possible to carry out a cleaning phase on the product before phase b).

Preferably, after phase c), is the product ? coated or decorated with a powder coating in order to obtain the above mentioned advantages.

This provides that the powder coated product undergoes a polymerization process of the paint, preferably conducted by setting one or more? infrared lamps at a temperature of at least 180°C and exposing the powder coated product to the lamp(s) so set for the pi? 180 seconds.

In practice, the polymerization pu? be obtained preferably by setting one or more? infrared lamps at a temperature between 180?C and 500?C and exposing the powder coated product to the lamp(s), so set for a time interval, inversely corresponding to the temperature interval, between 30 seconds and 180 seconds. For example, the temperature can be set at 250?C and the product can? be exposed for 90 seconds.

Will the sector technician know? choose the temperature and the time interval according to the thickness of the product, its density? and the distance from the infrared lamp or lamps.

The present invention ? also directed to a machine for coating a product in composite material derived from wood according to claim 27.

In particular, the machine includes:

- a loading section of the product to be coated;

- a discharge section for the coated product;

- an advancement path for the product from the loading section to the unloading section;

- a primer application station with properties? Reflective and electrostatic IR, especially with one or more? characteristics described above in relation to claim 1, e

- a heating station of the product coated with a primer with properties? IR reflective and electrostatic, preferably as described above, and configured to carry out solidification of the primer on the product.

The product feed path develops from the loading section to the unloading section and crosses the primer application station and the product heating station.

These stations are therefore functionally interposed between the product loading section and the product unloading section, in the sense that regardless of the respective positions of the stations with respect to the product loading and unloading section, considering the operation of the machine, these stations are located between the two sections, so that the product is loaded into the loading section, is coated at these locations and finally reaches the unloading section.

Downstream from the primer application and primer heating station, the product can be subjected to varnishing, polymerisation and possibly also to a sublimation printing process.

The machine can also include one or more features, or locations, described with reference to claims 28-33.

? it is clear that any other stations provided in the machine are also functionally interposed between the loading section and the unloading section.

The present invention also relates to a product made of wood-derived composite material provided with a surface layer of primer described above, according to claim 34. Preferably the product has a surface layer of solidified primer.

Preferably the thickness of the primer layer ? of at least 10?m, more? preferably still it ? between 10?m and 30?m.

The present invention also relates to a product made of wood-derived composite material provided with a layer of primer and powder coated, according to claim 36. In other words, it relates to a product made of wood-derived composite material comprising a primer layer and a of powder paint, cured.

Preferably the layer of powder paint ? of at least 80?m; more preferably still the layer of powder coat ? between 80?m and 110?m.

The present invention also relates to a product made of wood-derived composite material according to claim 37 coated with the coating method described above.

Finally, the present invention relates to the use of the primer described above, according to claim 38, for electrostatically charging a product made of wood-derived composite material and as a base for powder coating such a product.

Short list of figures

Further characteristics and advantages of the invention will be better highlighted by examining the following detailed description of preferred, but non-exclusive embodiments thereof, illustrated for indicative and non-limiting purposes, with the support of the attached drawings, in which:

- figure 1 ? a schematic view of a wood-based composite material panel on which ? applying the primer according to the present invention;

- figure 2 ? a flowchart of a preferred embodiment of the method for coating the panel shown in Fig. 1 ;

- figure 3 ? a schematic view of a loading section of a panel coating machine shown in Fig. 1 ;

figure 4 and figure 5 are schematic views of a cleaning station of a machine for coating the panel in figure 1;

figure 6 and figure 7 are schematic views of two versions of a primer application station according to the present invention on the panel in figure 1;

- figure 8 and figure 9 are schematic views of two versions of a heating station of the panel shown in figure 1 on which ? primer has been applied;

- figure 10a and figure 10b are schematic views of two versions of a powder coating station of the panel shown in figure 1 on which ? the primer according to the present invention has been applied;

figure 11 and figure 12 are schematic views of two versions of a polymerization station of the powder-coated panel shown in figure 1;

- figure 13 ? a schematic view of a portion of the machine including a polymerization station and a sublimation station;

- figure 14 ? a schematic view of a relief section of the panel shown in figure 1 decorated.

- figures 15 and 16 show graphs of the internal temperature of MDF panels, as a function of time, measured inside the panels themselves during tests. Detailed description of the invention

? described below is a primer that can be applied to a product made of wood-derived composite material and preferably applied to a panel made of MDF wood fiber composite material.

For simplicity?, below it will be described? the invention with reference to an MDF panel, shown in figure 1 and identified as ?panel 1?, without however? wanting to limit the invention to a product of this particular type.

Before going into the merits of the invention, with reference to figure 1, ? a panel 1 is shown. Panel 1 has an upper face 2 and a lower face 3, not visible in the figure, and a series of side faces arranged in pairs on opposite sides of the panel, of which the front face is visible in figure 1 4 and the lateral face 5, positioned on the right in the figure.

Figure 1 shows a panel positioned horizontally, ie with the faces 2, 3 arranged horizontally and the side faces 4, 5 arranged vertically. A panel 1 positioned vertically, on the other hand, has the faces 2, 3 arranged vertically and one of the pairs to which the side faces 4, 5 belong horizontally, for example with the side face 5 arranged at the bottom and the opposite one at the top. For example, panel 1 has a length of 300 mm, depth? 200 mm, thickness 19.4 mm and a weight of 620 grams (density of about 0.51 grams per cm<3>).

? clear for? that for the purposes of the present invention ? It is possible to coat a product in composite material derived from wood of any shape or size. Therefore when described below in reference to panel 1 pu? be extended to any product in wood-derived composite material.

The primer described here comprises a resin matrix and a related solvent, which constitute the basic component of the primer, and a substance selected from metal oxides or metal-silicates, or a mixture of metal oxides and metal-silicates. In the preferred form of the invention, the substance ? choice among metal oxides.

Furthermore, in the preferred form of the invention, the primer comprises, as a matrix, a polyester or acrylic resin and, as a solvent, water. In practice, polyester or acrylic resin? present in a percentage by weight from 30% to 40%.

The presence of metal oxides and/or metal-silicates allows the primer, when applied to an MDF panel, to be able to powder coat the panel 1, forming a layer of paint that is suitably thick and durable over time.

In fact, the metal oxides and/or metal-silicates present in the primer allow:

- to electrostatically charge the surface of panel 1, to obviate the impossibility? of the raw panel 1 to be charged electrostatically in an adequate manner;

- to reflect the heat, ie the corresponding radiations, used in the polymerization process of the powder paint, and preferably to reflect the IR rays used to make the powder paint polymerize.

In practice, the advantages of the primer described here emerge when it ? applied to a panel 1 to be covered or decorated; in fact the primer, thanks to the presence of metal oxides and/or metal-silicates, first of all allows the powder paint to adhere to the surface of the panel 1, so as to preferably form a layer of paint of at least 80 µm and, secondly , allows the heat, and preferably the IR rays, used in the polymerization of the paint, or in subsequent other processes, not to create breakages in the wood fiber composite material of which the panel 1? constituted.

In fact, the radiations used in the heating process are, at least in part, reflected by the primer, thus not to overheat the panel 1 and the water or other substances present inside it. This limits the possibility that vapor capable of creating breakages in the panel 1 and in the covering layer present is formed inside it.

Preferably these metal oxides have properties Reflective IR, i.e. if irradiated with infrared rays they reflect part of the radiation with this wavelength. This implies that a panel 1 to which ? Once applied, the primer heats up in a lower manner than a raw panel 1, i.e. which does not? applied the primer described here.

This will be evident from the tests and results described below.

In the preferred embodiment, the base component of the primer is added with a mixture of titanium oxide (IV) Ti?2 and aluminum oxide Al2O3 which are respectively present in a percentage by weight between 9% and 11% and between 14% and 18% with respect to the total mass of the primer.

In general, metal oxides are present in the primer in a percentage between 20% and 35% by weight, and preferably between 23% and 31% by weight.

In addition to the components mentioned above, the primer can? understand one or more of the following substances which can be defined as adjuvants: a cross-linking reagent and/or a surfactant/dispersant and/or a rheological/levelling agent.

These substances are not essential for making the primer according to the present invention, but their presence in the mixture preferable to improve the dispersion of the metal oxides in the base component of the primer or to allow the primer to be applied to the panel 1 by spraying means.

In particular, the crosslinking reagent ? present in a percentage, with respect to the total mass of the primer, of between 3% and 5% by weight, the surfactant/dispersant between 1% and 4% by weight and the rheological/leveling agent between 1% and 2 %.

For example, in a particular embodiment of the primer described herein, the primer comprises Joncryl 79 at 30-40% by weight as resin, Zinc Oxide Solution #1 at 1-2% by weight as catalyst, Plastopal BTM at 3- 5% by weight as crosslinker, Hydropal WE 3500 at 1-2% by weight as surfactant, Dispex Ultra FA 4480 at 1-2% by weight as dispersant, Rheovis AS 1130 at 1-2% by weight as rheological agent , titanium (IV) oxide 9-11% by weight and aluminum oxide 14-18% by weight as metal oxides and a quantity? of water as a solvent to reach 100% by weight.

The primer can? be prepared by adding the metal oxides to the base component and to the adjuvants, if present, and mixing everything until a suspension is obtained, or the metal oxides can be added from the beginning directly into the resin matrix which is? then used in the preparation of the primer together with the other components.

As anticipated above, tests have been carried out to demonstrate that the primer allows, in the first place, to powder coat a panel 1 and, in the second place, that it has the ability to reflect, at least in part, the IR rays used in the polymerization process of the powder paint.

Try I

Proof ? was conducted on three MDF panels.

In particular, MDF panels with a length of 300 mm and a depth of 300 mm have been used. 200 mm and 19.4 mm thick each, with a weight of 620 grams (density of about 0.51 grams per cm<3>).

A first panel? been used raw, i.e. not coated with the primer, a second panel ? been coated with Joncryl 79 resin, in the absence of metal oxides, while a third panel? been coated with the primer described below.

In particular, for the coating of the third panel ? a primer was used comprising Joncryl 79 at 30-40% by weight, Zinc Oxide Solution #1 at 1-2% by weight, Plastopal BTM at 3-5% by weight, Hydropal WE 3500 at 1-2% by weight , Dispex Ultra FA 4480 at 1 -2% by weight, Rheovis AS 1130 at 1 -2% by weight, titanium oxide (IV) at 9-11% by weight, aluminum oxide at 14-18% by weight and a quantity of water as a solvent to reach 100% by weight.

The primer ? was applied to the MDF panel with a Wagner W100 gun and allowed to solidify, so as to form a primer layer of at least 10µm, and preferably a primer layer between 10µm and 25µm.

Later yes? proceeded to apply a powder coating on all three panels using a Corona CP-2100 gun.

From this test? emerged that the powder paint is not ? remained adhered to the raw panel and to the panel with only the resin Joncryl 79, while? remained adhered to the panel coated with the primer including metal oxides.

This demonstrates that the primer described here enables the surface of an MDF panel to be electrostatically charged and that it can serve as a base for powder coating an MDF panel.

Test II

Powder paint polymerization tests were carried out under the conditions described in test I. Although the manufacturer's indications were to polymerize the powder paint in an air oven at 130°C for 3 minutes, surprisingly ? it turned out that even setting the temperature of the IR lamps to a temperature of at least 180? and exposing the powder coated panel to lamps so? set for the pi? 180 seconds, the powder paint ? adequately polymerized forming a layer of at least 80?m.

In other words, the Applicant has identified a new method for making the powder paint polymerize.

In particular, tests have shown that by setting the IR lamps at a higher temperature, ? possible to decrease the exposure time.

For example ? It is possible to set the lamps at a temperature of 210?C or 250?C and cure at approximately 90 seconds of exposure, or set the lamps at a temperature of 450?C or 500?C and cure at approximately, respectively , 70 seconds or 30 second exposure.

Does this mean that you can obtain the polymerization of the powder paint in a shorter time interval than that traditionally considered necessary to obtain the polymerization.

This method? independent of the presence or absence of the primer, in the sense that excellent results have been obtained with this method also by carrying out the polymerization of the powder paint applied on a metal product, in the absence of a layer of primer.

Try III

The third test? been conducted to demonstrate the ability? of the primer described here to reflect IR rays.

Proof ? was conducted on four separate MDF panels.

Again, identical MDF panels of 300 mm length, depth 300 mm were used. 200 mm and 19.4 mm thick each, with a weight of 620 grams (density of about 0.51 g/cm<3>).

Two of these panels, identified as panels A and B, were used as raw panels, ie not coated with the primer, while the remaining two panels, identified as panels C and D, ? primer comprising metal oxides was applied.

In particular, as for test I, for the coating ? a primer was used comprising Joncryl 79 at 30-40% by weight, Zinc Oxide Solution #1 at 1-2% by weight, Plastopal BTM at 3-5% by weight, Hydropal WE 3500 at 1-2% by weight , Dispex Ultra FA 4480 at 1-2% by weight, Rheovis AS 1130 at 1-2% by weight, titanium oxide (IV) at 9-11% by weight, aluminum oxide at 14-18% by weight and a quantity of water as a solvent to reach 100% by weight.

The primer ? was applied to panels C and D with a Wagner W100 gun and allowed to solidify, so as to form a primer layer of at least 10?m, and preferably a primer layer between 10?m and 25?m.

Later yes? proceeded to coat panels C and D with a powder paint using a Corona CP-2100 gun.

In order to demonstrate the properties Reflective IR of the primer, yes? proceeded to heat panels A-D using IR lamps in such conditions as to polymerise the powder paint present on panels C and D, and to measure the internal and external temperature reached by panels A-D at 15s intervals.

In particular, ? was used a temperature control instrument equipped with 2 thermocouples of the Tersid company and 4 thermoregulators of the company and a thermoregulation system that uses relays? static and holding timer.

To heat the panels, 12 infrared lamps of the ceramic type of the company Lorenzoni S.r.l. were used; these lamps were arranged along a vertical plane on the ground so as to form two opposing groups which were each at a distance of 8 cm from the panel 1. Each group included 6 lamps. In each group the lamps were arranged in two rows of three: an upper row and a lower row so that? the top row and bottom row of one group faced the top and bottom row of the other group of lamps, respectively.

The two thermocouples have been associated from time to time with panels A-D in the following way: a first thermocouple ? been inserted inside the panel in a blind hole obtained in a lateral face (for example in face 4 or 5 shown in figure 1) and positioned at a distance, in depth, of 10 cm from the corresponding lateral face; a second thermocouple? instead it has been positioned in correspondence with an upper or lower face (for example in correspondence with face 2 or 3 shown in figure 1). In practice, the first thermocouple? been set up to measure the temperature reached inside them by panels A-D while the second thermocouple ? been set up to measure the surface temperature in correspondence with panels A-D.

In this test, each opposed group of IR lamps had an IR ray emitting surface of about 1500cm<2> and the area of each face of panel 1 irradiated by the IR rays had a surface of about 650cm<2>.

In order to conduct the test, four tests were performed consecutively, one for each panel A-D.

In each test, the corresponding panel A-D ? was positioned with the relative thermocouples between the IR lamps off, the IR lamps were set at the pre-established temperature and, at t0, the IR lamps were switched on for 90 seconds. After this interval of time, the lamps have been turned off and moved away from the corresponding panel A-D and by means of a special fan, ? proceeded to speed up the cooling of the panels A_D.

In particular, in the tests conducted on panels A and C, the lamps were set at 180?C while in the tests conducted on panels B and D, the lamps were set at 210?C. From the time t0 up to at least 285 seconds, the internal temperature (T1) and the external temperature (T2) were recorded every 15 seconds.

The results obtained are shown in the following table:

As shown in the table, by setting the lamps to 180?C, panel A, raw, reached a maximum internal temperature of 55?C after 210s, while panel C, provided with a layer of primer, reached a maximum internal temperature of 47?C after 225s, i.e. 8?C lower than the internal temperature of panel A.

By setting instead the lamps at 210?C, panel B, raw, reached a maximum internal temperature of 56?C after 210s, while panel D, provided with a layer of primer, reached a maximum internal temperature of 53?C after 210s, i.e. 3?C lower than the internal temperature of panel B.

These differences can also be appreciated in the graphs shown in figures 15 and 16.

In particular, the graph in figure 15 shows the trend of the internal temperature reached by panel A, raw, and by panel C, with the primer, while the graph in figure 16 shows the trend of the internal temperature reached by panel B, raw , and from panel D, with the primer.

In both graphs you can? visually appreciate that the curves of panels C and D have lower values than the maximum values reached by the curves of panels A and B.

The above data can be used to provide an estimate of the refractive coefficient of the primer.

First of all ? to consider that the incident heat on a panel A, B without primer ?

where K ? a constant of proportionality? which takes into account the heat emitted by the lamps and the incident surface of the panel?,? ?t of the panel exposure time to the heat flux.

From the laws of thermology, ? is it possible to say that the heat can? also be expressed as absorbed heat

where m ? the mass of the panel, c its specific heat and ?? the difference in temperature measured inside the panel between the maximum temperature reached and that of the initial state.

In case you apply the primer to the panel, ? possible to write that the heat absorbed by the panel, or not reflected by the primer, ? a fraction of the incident one produced by the lamps:

where a, the reflection coefficient of the primer, ? a number between 0 and 1, while the subscript p indicates the quantities obtained with the application of the primer.

Since all the heat incident on the panel (and transmitted by the primer) causes an increase in temperature inside the panel itself, ? possible to put

and, dividing member by member, we obtain the expression for the reflection coefficient of the primer:

Reporting the values measured in the tests at 180?C and 210?C, with and without primer, ? it is possible to obtain that:

- considering that in the tests at 180?C, panel C, with the primer, shows an increase in internal temperature from 27?C to 47?C, while panel A, raw, shows an increase in internal temperature from 26?C at 55?C, the reflection coefficient a ? equal to 0.31. From here it can be seen that 31% of IR rays are reflected;

- considering that in the tests at 210?C, panel D, with the primer, shows an increase in internal temperature from 26?C to 53?C, while panel B, raw, shows an increase in internal temperature from 26?C at 56?C, the reflection coefficient at ? equal to 0.10. From here it can be seen that 10% of IR rays are reflected.

The results of test III demonstrate that the primer described here has a reflection coefficient of at least 0.10, and preferably between 0.10 and 0.31, and that therefore the primer described here allows to reflect at least 10% of the incident IR radiations, and preferably to reflect incident IR radiation in a range between 10% and 31%.

The Applicant reserves the right to conduct further tests to demonstrate the ability? of the primer to limit the internal heating of an MDF panel placed in an air oven.

The results of the tests described above can also be extended to an alternative embodiment of the primer, comprising metal-silicates with properties Reflective IRs. The metal-silicates can be present in the primer as an alternative to the metal oxides or in addition to them, according to the weight percentages mentioned above.

As anticipated above, the advantages of the primer emerge by considering the primer applied to a panel 1 to be coated.

In practice, the primer allows you to overcome the limitations of the technique present up to now which did not allow powder coating an MDF panel.

This ? allowed by the presence of metal oxides and/or metal-silicates which allows you to powder coat an MDF panel with excellent results, i.e. it allows you to create a layer of powder paint on the MDF panel preferably of at least 80?m, more? preferably between 80?m and 110?m.

Furthermore, the primer limits, or prevents altogether, thanks to the properties? reflecting IRs demonstrated above, the formation of cracks in the panel and, consequently, in the layer of powder paint, due to the evaporation of water, or other components, caused by heating of the panel during the polymerization process. In fact, thanks to the presence of metal oxides and/or metal-silicates, the IR radiations used to polymerise the powder paint are reflected by the primer and do not reach, or reach in a limited way, the wood fiber composite material of panel 1 , what? so as not to cause significant increases in temperature inside the panel.

Basically, thanks to the primer described here, not only is it possible to powder coat an MDF panel, obtaining the advantages described above, but the opportunities for damaging the panel are limited or eliminated, making it more fast the coating process why? it is not necessary to carry out checks to verify the possible damage of the panels due to the heat, and the costs for covering the panels are reduced, because? significantly reduces the amount? of panels rejected due to damage due to overheating of the wood fibres.

The primer also allows panel 1 to be given a better aesthetic appearance because the presence of metal oxides in the primer gives panel 1 a uniform colour, preferably white, and a texture which is pleasant to the touch.

Possibly ? It is possible to add colored pigments to the primer to give a very precise color to the primer.

In practice, the primer pu? be used to coat and/or decorate a panel 1 both in the sense that it can? itself constitute a product for covering and/or decorating a panel 1, both in the sense that it can? form a basis on which to carry out the powder coating.

Optionally the primer pu? also include a dissolved salt, such as sodium chloride, or an allotropic form of graphite, in order to give the primer greater properties? electrostatic.

For example, the allotropic form of graphite can? be present in the primer at 1% by weight.

With reference to the flowchart shown in figure 2 ? described a method for coating or decorating a panel 1 using the primer described above.

In particular, the method provides for a step a) in which a panel 1 to be coated is made available; panel 1 can? be made available manually or through an automated system, such as a Cartesian system or an anthropomorphic robot.

In practice, in step a) the panel 1 is positioned at a workstation to carry out step b) which provides for applying the primer described above to the panel 1. The primer can? be applied by immersing the panel in a tank containing the primer itself, or by applying the primer with a brush or, preferably, by spraying the primer on the panel using suitable spraying means, such as spray ramps or spray guns.

In the subsequent step c) the panel 1, with the primer applied, is heated to cause the primer to solidify and create a layer of primer on the panel 1. Preferably, the solidified primer has a thickness of about 10?m? 30?m and preferably 20?m.

? to underline that the panel 1 with the solidified primer can? be defined as a panel 1 decorated, why? even the primer alone? able to give a pleasant appearance to the panel 1 thanks to the presence of the metal oxides, as described above.

Phase c) can? be obtained by heating the panel using infrared radiation and/or hot air. For example ? Is it possible to heat with infrared lamps for about 30-40 seconds at 80?C-90?C, or ? It is possible to heat using a hot air oven for 1-2 minutes at a temperature between 70?C and 90?C.

In the preferred embodiment of the method, after step a) the panel 1 is subjected to a cleaning process to eliminate any dust present on the panel. This process can also have the purpose of making more? smoothed the surfaces of panel 1, i.e. to eliminate any irregularities? surface dates from the wood fibers of which? composed panel 1.

Preferably the cleaning process ? implemented using cleaning means, including for example one or more? brushes and/or a high pressure jet of air. The panel can be held in place on the worktop with clamps or by making holes in the worktop and creating a negative pressure at the worktop itself by means of suction, such as a suction pump.

In practice, the negative pressure ensures that the panel 1 does not move on the work surface following the stresses exerted on it by the cleaning means and also allows the dust generated by the cleaning process to be sucked in so that does not disperse into the environment.

Before phase b) panel 1 can? be heated and subsequently cooled so as to decrease, or eliminate, the water content present in panel 1. In this way the possibility is further reduced? that cracks form in panel 1 as a result of the subsequent phases which provide for heating of panel 1.

In this phase the panel ? medium heated to 50?C-80?C for 1-2 minutes.

As anticipated above, panel 1 can? be considered coated and/or decorated even at the end of phase c). In case it is for? is it necessary to decorate and/or cover panel 1 in a more elaborate, ? It is possible to envisage further decoration phases of panel 1.

In particular ? It is possible to carry out phase d) which involves applying a powder paint to the panel.

? It is possible to apply powder paint to panel 1 in a known manner. ? For? It is preferable to powder paint a panel 1 in a workstation equipped with guns for powder painting and providing powder paint suction means which are not required. adhered to panel 1.

As it is known, ? It is possible to provide means for electrostatically charging the powder paint. Known ways to charge powder paint electrostatically involve the use of triboelectric or corona effect guns or fluid bed systems.

The extracted powder paint is concentrated via a cyclone system and then fed back to the powder coating guns. In this way, the advantages associated with the use of powder paint (elimination of VOC emissions, elimination or reduction of the need for intermediate sanding, application of powder paint to the side surfaces in a single step) ? possible to reuse the powder paint that is not ? remained adhered to the panel 1, in such a way as to reduce the costs relating to the purchase of the powder paint itself.

Subsequently to the painting steps, the panel is subjected to a polymerization step e), in which the polymerization of the powder paint is induced.

The polymerization of the powder paint induces the formation of a seamless coating on panel 1.

In practice, in this phase, the paint present on the panel hardens and forms a uniform layer between 80?m and 110?m which covers the whole surface of the panel 1 without the need to to carry out intermediate sandings and without the need? to make suitable applications of paint on the edges of the panel 1 or to make borders.

The polymerization can be induced by heating the painted panel with hot air at 130?C for 3 minutes and/or using infrared rays, e.g. emitted by an infragas or ceramic lamp, at a temperature of approximately 180?C or 210?C for 90 seconds.

Pi? advantageously ? Curing can be induced by setting the temperature of the lamp(s) to 250?C and exposing the powder coated panel to the lamp(s) so that the curing is induced. set for 90 seconds. Preferably the panel has a distance from the lamp or lamps of 8 cm.

In this way the time required for the powder paint to polymerize is halved, compared to the times required by traditional methods

? It is possible to carry out phase e) by arranging the infrared lamps on opposite sides with respect to panel 1, i.e. by arranging one or more? infrared lamps towards face 2 and arranging one or more? infrared lamps towards the face 3.

? It is also possible to provide means for detecting the temperature, to measure the temperature in correspondence with the panel 1, so as to to be able to regulate the heating of panel 1 according to the temperature detected.

For example ? It is possible to carry out the retrofit heating regulation, automatically, by fixing the infrared lamps to a corresponding frame susceptible to mutual approaching and moving away from each other, i.e. with respect to panel 1. In this way, when? necessary to increase the temperature at panel 1, one or both frames approach each other, and when? necessary to decrease the temperature, one or both frames move away from each other.

In practice, if the temperature is outside a predefined range both on face 2 and on face 3, both frames approach or move away to bring the temperature back into the desired range, while if the temperature is outside the range default in correspondence of only one of the faces, for example of the face 2, only the corresponding frame, with the relative infrared lamps, approaches or moves away from the panel 1. Therefore the retrofit control pu? be performed selectively for each frame and for each face of panel 1.

Retrofitted ? can you also expect to adjust the? intensity? of the infrared lamps and, if means for moving the panels are provided, ? is it possible to vary the speed? of the panel handling means.

This heating method can also be used in step c).

After the polymerization phase, panel 1 can? be cooled with air, preferably cold.

As anticipated above, panel 1 can? also be decorated by sublimation printing. In fact, the method can foresee a phase f) in which on the powder-coated panel ? carried out a sublimation printing process, batch or continuous.

In essence, powder paint has the advantage of being able to function as a base on which to imprint the decoration during the sublimation printing process.

Sublimation printing can be carried out according to a method known in the sector, on only one panel 1 at a time or on more? panels 1 simultaneously, using a sublimation film known in the sector and making the sublimation take place in a negative pressure environment (from -100 millibar to -360 millibar) at a temperature between 140°C and 180°C for a time between 1 minute and 30 seconds and 3 minutes and 30 seconds

At the end of the sublimation phase, the panel is decorated with a particular motif, or design, initially present on the sublimation film and then transferred to panel 1.

At this point the decorated panel 1 can? be downloaded from the workstation, manually or via a Cartesian system or an anthropomorphic robot.

Overall, the method described above makes it possible to coat and/or decorate a panel 1 in a more efficient way. easy, fast, cheap and efficient compared to the methods known today thanks to the application of the primer described above and the possibility? to powder coat the MDF panel.

The coating method of a panel 1 according to the present invention comprises steps a), b), c) and, optionally, according to the need, also steps d), e), f).

The method can be better understood also taking into consideration the machine to decorate a panel 1 that will be? described below with reference to figures 3-14.

Does the machine have a loading section 11 of one or more? panels 1, shown in FIG. 3, and a discharge section 90 of one or more? panels 1, shown in figure 14.

The machine can be arranged to coat one panel 1 at a time, or, preferably, to coat several? 1 panels at the same time.

The machine also has an advancement path for the panels 1 which can be also configure as a support and advance plane for the 1 panels.

In essence, the machine pu? provide for the movement of the panels 1 on a support and advancement surface, keeping the panels 1 in a horizontal position, or can it? provide for the movement of the panels 1 by means of the hooking means, described below, keeping the panel 1 vertical. Alternatively ? possible to provide some stations in which the panel 1 ? positioned horizontally and others in which ? placed vertically.

In particular, the loading section 11, shown in Figure 3, has a support surface 12 on which the panels 1 to be decorated are positioned and a movement system 13 comprising a guide 14 for a manipulator 15 provided, for example, with a suspension device 16 at the end of which? inferior ? fixed a suction cup designed to abut against a panel 1 to move it from a pick-up station, for example from a pallet 17, to the support surface 12.

The manipulate 15 ? susceptible of movements along the guide 14 parallel to the ground, in a first direction and in a second direction opposite to the first, and of movements perpendicular to the ground, downwards or upwards, as shown by the relative arrows in figure 3.

Alternatively, as a replacement for the manipulator ? You can use an anthropomorphic robot, such as a collaborative robot not shown in the figure.

Once positioned on the support surface 12, the panel 1 is moved, for example by means of a conveyor belt, to a cleaning station 20 shown in figures 4-5.

The cleaning station 20 has a support and advance plane 21, on which the panels 1 are placed. The support and advance plane 21 ? arranged to move the panels 1 along a longitudinal axis, in the direction of the arrow shown in figure 4.

The support and advancement plane 21 ? drilled in correspondence with at least a portion of the surface, i.e. it has a series of through holes 22, visible in figure 4.

Below the support and advancement surface 21 ? there is a containment tank 23 which opens towards the external environment precisely in correspondence with the through holes 22. The containment tank 23 is present. furthermore in fluid communication with a suction pump 24 capable of generating a negative pressure in correspondence with the through holes 22 of the support and advancement plane 21.

The cleaning station 20 ? equipped with cleaning means 25 for cleaning the panels 1. Preferably, these cleaning means 25 comprise one or more? brushes 26 and/or one or more? nozzles 27 arranged to emit a jet of pressurized air, schematically shown in figure 5.

The brush, or brushes, 26 and the nozzles 27 can be positioned in series above the support and advancement surface 21, so that the panels 1 can first be cleaned by means of the brush/brushes 26 and subsequently cleaned by means of of the pressurized air fed by the nozzles 27. ? can also provide one or more? brushes 26 before the support and advancement surface 21, facing upwards, as shown in figure 5. In this way, the manipulator 15, before placing the panel 1 on the support and advancement surface 21, can position it in correspondence with said brush/brushes 26 so as to also clean the face intended to abut against the support and advancement surface 21.

The fact that the support and advancement surface 21 has through holes 22 in correspondence with which a negative pressure is applied to the panel 1 allows both to ensure that the panel 1 remains in its seat on the support and advancement surface 21 during cleaning i.e. that it does not move in response to the stresses imparted by the cleaning means 25, and to suck up the cleaning residues of the panel 1 into the containment tank 23, preventing them from dispersing in the environment.

The car ? also equipped with a station 30 for applying the primer described above on one or more? panels 1. Figures 6 and 7 show two embodiments of a primer application station 30: the one shown in figure 6 has a support and advance plane 21 on which panels 1 are placed and moved in a horizontal position in the direction indicated by arrow, while figure 7 shows a station 30 in which the panels 1 are moved along an advance path provided with hooking means for the panels 1, not shown in the figure, which keep the panels 1 vertical. Such means can comprise platforms and conveyors known in the field.

In the station 30 shown in figure 6 the primer ? applied to the panels 1 by means of spray ramps or spray guns 31 positioned above the support and advancement surface 21. In figure 6 ? schematically shown the primer sprayed by the relative spray guns 31.

In figure 6, ? possible to see that under the support and advancement surface 21, on the opposite side to the spray ramps or spray guns 31, is there is a containment tank 32 which collects the excess primer which has not adhered to the panels 1.

The containment tank 32 ? also equipped with a primer recovery system; in fact, the containment tank 32 has an outlet duct 33 connected to a delivery pump 34 which sends the excess primer collected in the containment tank 32 to the spray ramps or to the spray guns 31. The station 30 ? also equipped with one or more tanks, not shown in the figure, in which the primer is prepared and collected and which are also connected to the spray ramps or spray guns 31.

Between the containment tank 32 and the delivery pump 34 ? preferably a filter unit 35 is provided, which filters the primer collected in the containment tank 32 from any fragments of the panels present.

Preferably station 30 ? also equipped with an overturner, not shown in the figure, which allows panels 1 to be overturned so that the primer can be applied to both face 4 and face 5 of panels 1.

As anticipated above, ? It is possible to create a station 30 arranged to keep and move the panels 1 in a vertical position, as shown in figure 7. In this version, the station is provided with two series of spray ramps or spray guns 31 facing each other: the panels 1 are moved between the two spray ramps or between the two sets of spray guns 31, in such a way that each of the two faces 2 and 3 of the panels 1 faces one of the two spray ramps or one of the series of spray guns 31.

The machine also comprises a station 40 for heating the panels 1 coated with the primer in the previous station 30. Also this station can? be made in such a way as to advance the panels arranged horizontally or vertically.

In particular, figure 8 shows a version of the station 40 provided with a support and advance plane 21 configured as a conveyor belt on which one or more can be positioned. panels 1, movable in the direction shown by the arrow.

Station 40? provided with heating means 41 to obtain solidification of the primer and, preferably, to evaporate the water present in the primer as a solvent.

Said heating means 41 preferably comprise infrared lamps 42, preferably arranged in series above and below the support and advancement surface, and/or a hot air oven 43. Said heating means 41 are arranged to heat both faces 2, 3 of panels 1 so that the primer solidifies.

Figure 9 shows a station 40 in which the panels 1 are moved vertically by means of suitable hooking means 44. This station also comprises infrared lamps 42 and/or a hot air oven 43 arranged to heat both faces 2, 3 of the panels 1 to which ? primer has been applied.

The heating of the panels, when carried out using infrared lamps, occurs at a temperature of 80-90 degrees for 30-40 seconds; if it is done in an air oven, the panels are heated for 1-2 minutes at 80-90°C.

The machine comprises, with reference to figure 10a, preferably a powder coating station 50. The station 50 shown in Figure 10a provides for moving the panels 1 horizontally and, therefore, comprises a support and advance plane 21, preferably configured as a mobile Teflon carpet, which moves the panels 1 in the direction indicated by the arrow.

Above the support and advancement surface 21 there are one or more? paint guns 51 for powder coating the panels 1. Under the support and advancement plane 21 ? instead, there is a suction hood 52 connected to a suction fan 56, which sucks in the powder paint which is not adhered to the panels 1 and which conveys it to a powder paint recirculation system. The recirculation system comprises a doctor blade 53, a cyclone 54 and a power center 55 and allows the powder paint collected in correspondence with the suction hood 52 to be conveyed to the paint gun 51 through relative ducts.

Before the suction fan 56 ? preferable to install a filter 57 to block any particles of powder paint that is not? been picked up by Cyclone 54.

Optionally ? It is possible to make the powder coating station 50 so as to paint the panels 1 vertically, as shown in figure 10b.

Preferably the machine also comprises a polymerization station 60, shown in figure 11, which has the function of inducing the polymerization of the powder paint which has remained adhered to the panels 1.

The polymerization station 60 comprises a support and advance plane 21 configured as a Teflon moving carpet with warp and weft covered by a PTF material loaded with glass, so that it is resistant to high temperatures. this support and advance plane 21 moves the panels 1 in the direction indicated by the corresponding arrow.

The polymerization ? obtained through infrared lamps 61 positioned above and below the support and advancement plane 21.

The infrared lamps 61 are mounted in series on respective frames 62a, 62b. In practice, the polymerization station 60 comprises an upper frame 62a and a lower frame 62b, each of which is equipped with a series of infrared lamps 61.

Each frame 62a, 62b ? arranged to be movable with respect to the support and advancement surface 21, ie each frame 62a, 62b ? susceptible to movements towards and away from the support and advancement surface 21, in the direction indicated by the relative arrows.

The polymerization station 60 also comprises means for detecting the temperature 63 at the support and advance plane 21. Preferably these means for detecting the temperature 63 are positioned both above and below the support and advance plane 21.

They can be configured as optical pyrometers or as temperature sensors, and have the function of detecting the temperature in correspondence with the faces 2, 3 of the panels 1.

This temperature value? sent to a control unit, not shown in the figure, which compares the temperature value with a pre-established temperature interval. If the detected temperature deviates from the pre-established temperature range, the control unit controls the movement of one or both of the frames 62a, 62b towards or away from the support and forward plane 21. Basically, the control unit controls the movement of one or both frames 62a, 62b in such a way as to allow the temperature to return within the predetermined range. Preferably, the ecu takes into account, in this calculation, also the speed? of progress of the panels and of? intensity? of the radiation emitted by infrared lamps.

The frames 62a, 62b are arranged to move selectively, i.e. independently of each other, according to the temperature detected by the corresponding temperature detection means 63.

The 60 curing station ? also equipped with a hot air ventilation system 64.

Also in this case, the above described pu? be carried out keeping the panels vertical, as shown in figure 12.

A location of this type pu? also be provided as a station 40 for heating the panels 1 to make the primer solidify.

The machine preferably also comprises a sublimation printing station 70 on the panel 1, i.e. a station in which an image previously present on a film of

Claims (32)

sublimation. Station 70? shown schematically in Figure 13 downstream of the polymerization station 60 and consists of a sublimation printing station known in the sector. Finally, the machine comprises a section 90, shown in figure 14, for unloading the coated and/or decorated panels 1, provided with a system similar to that described with reference to the loading section 11, but arranged to unload the decorated panels from the support 91 and stack them, for example, on a pallet 92. In general, the machine according to the present invention comprises at least the loading section 11, the primer application station 30, the panel 1 heating station 40 to solidify the primer on the panels, the unloading section 9 and a progress of the panels that can? be configured as a support plane and advancement 21 that pu? be shared between the different workstations or that pu? be done differently at different locations. A machine with these workstations allows to make a panel 1 coated with the primer described above. The other stations of the machine described above are to be considered optional in the sense that the machine can? understand one or more of the other stations, preferably however, the machine comprises at least one powder painting station and a relative powder paint polymerization station, so as to form a powder coated panel 1 which allows to obtain the above advantages. 1. A primer applicable on a product (1) in composite material derived from wood comprising a resin matrix, a matrix solvent and a substance selected from metal oxides or metal-silicates, or a mixture thereof. 2. Primer according to claim 1, wherein the metal oxides and/or metal silicates are 20-45% by weight. 3. A primer according to claim 1 or claim 2, wherein the metal oxides and/or metal silicates have properties Reflective IRs. 4. Primer according to any one of the preceding claims 1-3, wherein the metal oxides and/or metal-silicates have properties electrostatic or are electrostatically chargeable. 5. Primer according to any one of the preceding claims 1-4, wherein the resin is at 30-40% by weight. 6. Primer according to any one of the preceding claims 1-5, wherein the matrix is a polyester resin or an acrylic resin. 7. Primer according to any one of the preceding claims 1-6, wherein the solvent is waterfall. 8. Primer according to any one of the preceding claims 1-7, wherein the metal oxides are selected from titanium oxide or aluminum oxide, or are a mixture of titanium oxide and aluminum oxide and are initially dispersed in the resin matrix. 9. A primer according to any of the preceding claims 1-8, wherein the metal oxides are a mixture of titanium oxide at 9-11% by weight and aluminum oxide at 14-18% by weight. 10. Primer according to the previous claim 8 or 9, wherein the oxide <? > titanium? titanium (IV) oxide, TiO2, and aluminum oxide ? Al2O3. A primer according to any one of the preceding claims 1-10, comprising a crosslinking reagent and/or a surfactant/dispersant and/or a rheological/leveling agent. 12. Primer according to the previous claim 11, wherein the crosslinking reagent is? at 3-5% by weight and/or the surfactant/dispersant? at 1-4% by weight and/or the rheological/leveling agent ? at 1-2% by weight. A primer according to any one of the preceding claims 1-12, comprising an electrostatically charged or electrostatically chargeable allotropic form of graphite and/or a solubilized salt, preferably NaCl. 14. Primer according to any one of the preceding claims 1-13, comprising coloring pigments of the primer itself. 15. Primer according to any one of the preceding claims 1-10, consisting of a resin matrix, a solvent and a substance selected from metal oxides or metal-silicates, or a mixture thereof. 16. A method of coating a product (1) in composite wood material comprising the steps of: a) make available a product (1) made of wood or its derivatives; b) apply to said product (1) a primer with properties? reflective and electrostatic IR; c) heating the product (1) to obtain the solidification of the primer applied in phase b). 17. Method according to the previous claim 16, wherein the primer applied in step b) is a primer according to any of the preceding claims 1-15. <? > 18. Method according to the preceding claim 16 or 17, wherein the primer is applied by immersing the product (1) in a tank containing the primer or ? applied by spraying the primer on the product (1). 19. Method according to any one of the preceding claims 16-18, wherein during step c) the product (1) is? heated by infrared rays and/or by hot air. 20. Method according to one of the preceding claims 16-19, wherein in step c) the product (1) is brought to a temperature of 80?C-90?C for 30-40 seconds by means of infrared rays. 21. Method according to one of the preceding claims 16-20, wherein in step a) the product (1) is? made available manually, or by means of a Cartesian system or an anthropomorphic robot. 22. Method according to any one of the preceding claims 16-21, wherein after step a) ? carried out on the product (1) a cleaning process to eliminate any dust present on the product (1) itself. 23. Method according to any one of the preceding claims 16-22, wherein, before step b) the product (1) is? heated and then cooled to reduce, or eliminate, the water content in the product (1). 24. Method according to any one of the preceding claims 16-23, comprising a step d): applying to the product (1) a powder paint, preferably applied in the absence of intermediate sanding, subsequent to step c). 25. Method according to the preceding claim 24, comprising a step e) in which the powder-coated product (1) undergoes a paint polymerization process, preferably carried out by setting one or more? <? > infrared lamps at a temperature of at least 180?C and exposing the powder-coated product (1) to the lamp(s), so? set for at most 180 seconds. 26. Method according to the preceding claim 25, comprising a step f), subsequent to step e), of sublimation printing or sublimation thermoprinting on the product (1). 27. Machine for coating a product (1) in composite material derived from wood comprising: - a section (11) for loading a product (1) to be coated; - a section (90) for discharging the coated product (1); - a feed path for the product (1) from the loading section (11) to the unloading section (90); - a station (30) for applying a primer with properties? reflective and electrostatic IR, preferably according to any one of the preceding claims 1-15, on the product (1) to be coated and - a station (40, 60) for heating the product (1) coated with said primer and configured to solidify the primer on the product (1), being said station (30) for applying the primer and said station (40, 60) for heating the product (1) functionally interposed between the product loading section (11) and the product unloading section (90) (1) . 28. Machine according to claim 27, wherein the advancement path of the product (1) comprises a support and advancement plane (21) of the product (1) configured to keep the product (1) in position <? > horizontal or in which the path of advancement of the product (1) comprises hooking and advancement means (44) of the product (1) arranged to keep the product (1) in a vertical position. 29. Machine according to claim 27 or 28, wherein the primer application station (30) comprises a primer tank, means (31) for spraying the primer on the product (1) connected to the tank and a tank (32) of collection of primer not adhered to the product (1). 30. Machine according to any one of the preceding claims 27-29, wherein the product heating station (40, 60) (1) comprises one or more? series of infrared lamps (42, 61) and/or an air oven (43, 64). 31. Machine according to any one of the preceding claims 27-30, comprising a powder painting station (50) and a powder paint polymerization station (60) functionally positioned downstream from the primer application station (30). 32. Machine according to the previous claim 31, wherein the polymerization station (60) of the product (1) comprises two series of infrared lamps (61) positioned on opposite sides with respect to the feed path (21) of the product (1) , wherein each set of infrared lamps (61) ? constrained to a relative frame (62a, 62b) which can move towards and away from the feed path (21) itself, said machine comprising at least one temperature sensor (63) positioned at the feed path (21) and a control unit configured to receive the temperature value detected by the at least one temperature sensor (63) and to compare this value with a reference temperature range, in which the approaching or moving away from each <? >