HK1169083A - Process and apparatus for manufacturing decorative papers and/or panels for flooring or surfacing of furniture, walls, etc. - Google Patents

Description

Method and device for producing decorative papers and/or panels for floors or furniture coverings, walls and the like

The invention relates to a method and a device for producing floor or furniture coverings, decorative papers and/or panels for wall surfaces, decorative foils, filter papers, kraft papers and the like from powdered aminoplasts and/or phenoplasts and/or mixtures in this way and/or mixed with additives.

The invention relates in particular to decorative papers, facing foils, the manufacture of kraft papers for high-and low-pressure applications, boards comprising these products, and boards made of gypsum or other materials for wall surfaces or false ceilings, and filter papers.

As is known, decorative papers for the manufacture of panels for floors or furniture facings, walls and the like are often obtained from printed and/or coloured papers, which are immersed in a liquid solution of a polymeric resin (generally a melamine resin) or a mixture of a resin with other compounds; after impregnation and drying, the paper is then usually coated with a mixture of polymeric resins containing particulate matter, such as corundum and/or glass microspheres, and dried, possibly further coated with other protective and/or finishing compositions, and dried again. The paper thus produced is therefore mainly cut into pieces and used, pressed onto wood or MDF chipboard, or combined with phenolic paper to obtain panels for furniture doors, or slabs for floor doors, or panels for wall doors, etc. For purposes of this specification, the terms "polymerization" and "polymer" shall also include "polycondensation" and "condensation polymer," respectively.

The current production systems use long production lines mainly formed by unwinders, dipping baths, drying ovens, first spreading machines, ovens, second spreading machines, another oven, possibly third spreading machines and respective ovens, cooling units, winding machines and/or cutting machines and paper stacking units.

These lines are therefore extremely long and expensive in terms of energy consumption, they generate a large amount of starting and ending chips and present difficulties in stopping the production in progress.

A more recent technique for manufacturing panels for floors or furniture facings, walls, floors, etc., so-called direct printing, avoids the use of decorative paper, since the desired pictures are printed directly onto the ready-made panels. The plates, suitably treated and prepared (in particular by means of a treatment for sealing the surface porosity and possibly imparting a uniform background colour), are coloured/decorated (by means of an indirect mono-or multicolour intaglio printing system, and by means of a digital printer) along a production line and dried, thus obtaining a ready-to-use product after final coating with a UV or IR polymer to impart protection and surface hardness.

Although certainly simpler compared to the conventional processes based on support impregnation and coating and subsequent pressing, this technique does not allow to apply on the surface thus produced components that improve the surface abrasion and scratch resistance, etc., nor does it allow to obtain a structured surface (i.e. reproducing wood grains, surface contours in stones, etc.), without using a surface that has been previously structured, on which the final colours/pictures can be subsequently printed only by digital printing techniques, which implies low productivity and not fully satisfactory quality.

It is an object of the present invention to provide a method and apparatus for manufacturing floor or furniture facings, decorative papers and/or panels for wall surfaces, facing foils, etc., which do not have the drawbacks of the known art described herein.

The present invention therefore relates to a method and a device for manufacturing decorative papers and/or panels for floors or furniture facings, walls and the like, as defined in the essential terms of the appended claims 1 or 11, as for their preferred aspects, as defined in the dependent claims.

Basically, according to the invention, instead of using the traditional impregnation and coating techniques with an impregnation bath and a water or solvent coating composition, the support (which may be a raw, pre-treated or pre-impregnated paper support of decorative paper, or a wood fibre support, or a board that has been pressed or laminated, or a plasterboard, etc.) is treated with a treatment composition in the form of solid particles, substantially in powder form.

In particular, the composition is a substantially dry solid composition in powder form with a polymeric component containing aminoplast (amino resins, in particular urea resins or melamine resins) and/or phenoplast (phenolic resins), which is used as such and/or mixed with additives and derivatives, for example from conventional dehydrating resins. This does not exclude components containing some water chemically or strongly physically bound within the powder material. However, the powder material must be pourable.

At least partial melting of the composition has been achieved, for example, by melting the amino resin.

More specifically, the composition comprises: one or more polycondensation thermosetting resins, in particular selected from aminoplasts, phenolics and mixtures thereof; one or more suitable catalysts (also in granular or powder form) for catalyzing the polymerization or crosslinking, such as an organic acid or a salt derivative from a strong acid + a weak base; optionally, depending on the kind of treatment to be carried out, other particulate substances, such as corundum, glass or ceramic microspheres, alpha-cellulose, etc.; optionally, other additives for the polymeric composition, organic and/or inorganic charges and fillers and/or minerals; optionally, decorative materials, such as reflective, sparkling, metallescent, and the like materials in the form of speckles, particles, fibers, and the like.

According to one variant, instead of or in addition to the polymeric component in powder form, the composition contains a mixture of reactants in powder form susceptible to reacting (condensing) to form at least one polymeric resin; in particular, the composition contains a mixture of reactants (such as melamine, urea, phenol, formaldehyde) in powder form, which are precursors of aminoplasts and/or phenoplasts. Derivatives of these compounds can also be used to obtain free-flowing powders, such as phenolates or paraformaldehyde.

The resin and/or powder reactants have a particle size of less than about 1000 microns, preferably from about 0.1 microns to about 500 microns.

Suitable powders can be manufactured, for example, from aqueous solutions of the components by known methods, such as spray drying. Suitable aqueous solutions, some of which are commercially available, may be prepared by methods known in the art, such as solutions containing prepolymers or precondensates of phenol, urea or melamine with formaldehyde. The powders of the components may be provided separately and mixed in the composition preparation device prior to application to the carrier. As long as the aqueous solutions of the specific components are compatible and do not react with each other, they may be mixed in advance, and the mixture is used to prepare a dry powder.

According to a first preferred embodiment, the composition is applied dry directly to the support to be treated, where it is melted by heating; a variant also proposes that the composition in the form of solid particles is melted and applied in molten form to the support by means of a suitable application device (for example, but not necessarily, a flat head, a roller system, a blade system).

In a first embodiment, the application of the composition is carried out by means of a powder doser which spreads the required amount of powder directly onto the carrier with precise distribution control. Since the powder material is at least partly melted after deposition on the carrier and thus fixed to its surface, it is not necessary to pre-treat the carrier surface with a liquid, such as glue.

The application of the powder composition is carried out by two-stage feeding (pre-feeding and fine feeding) or simply by a single feeding stage, where high precision is required.

The powder compositions are used in various amounts ranging from about 1 to about 200 grams per square meter in various applications, according to the final product and according to its mechanical and physico-chemical characteristics, also with particular reference to the characteristics of surface abrasion, lightness, scratch resistance.

The support on which the powder composition has been deposited is then subjected to a heating step, for example by means of infrared lamps, microwave systems, controlled flames or any other suitable heating system (although it is clear that no hot air is blown directly onto the support, as this blows off the deposited powder).

The heating is preferably carried out at a temperature of about 50 to about 200 ℃.

The heating determines the melting of the resin and the crosslinking and/or polymerization reactions required to form a polymeric layer on the support containing the additives that may be present.

After a possible cooling step, the support is ready for the following processing steps. In particular, the support, in particular a paper support, is ready to be pressed (at a pressure of about 5 to 100 bar) in a press together with other layers of various materials to obtain, with conventional systems and directly on the production line, boards, panels for the furniture or finishing sector, slabs for floors, etc. The pressing is preferably carried out at elevated temperature, most preferably 130 to 200 ℃. During this step, crosslinking of the polymer resins which have hitherto not been crosslinked or have only been partially crosslinked can be achieved.

Optionally, the support is subjected to a pre-heating step prior to application of the composition. This may assist in the adhesion of the powder to the carrier.

Preferably, both sides of the carrier are treated in the manner disclosed above, i.e. the composition is applied on both sides by separate procedures. The treatment compositions on both sides may be the same or different. If the carrier is sufficiently flexible, it can be inverted and processed on both sides in a single line in a continuous run. The rigid carrier may be inverted in the form of individual segments.

In a second embodiment, the treatment powder composition is pre-melted and then applied to the support by means of a suitable application device apt to dispense in a controlled manner the fluid composition onto the support.

The dry mixture, still containing one or more polymeric resins, catalysts and optionally other additives, all in solid form, previously prepared and/or mixed, is melted in a suitable furnace (for example electrically heated or heated by diathermic oil or other heating fluid) and applied by means of an application device with an optimal weight and percentage distribution both in the longitudinal direction (direction of feed of the support) and in the transverse direction (direction perpendicular to the direction of feed of the support).

Even in this variant, the resins used are the same as indicated above.

Obviously, for treating both sides of the support, two applicators running on each side of the support can be used.

According to the invention, the support treated may be a paper support for obtaining decorative paper and subsequently pressed with other layers to obtain a board; alternatively, it may be a pressed or laminated board made of wood fibers, gypsum, etc. The composition (again of the kind disclosed above) is applied (in a similar mode to those already disclosed, in particular in dry powder form, or after melting in fluid form, by means of a suitable application device) onto a support, which is a ready-to-use plate and optionally has printed decorations.

The invention has the following main advantages with respect to the known art:

a significant reduction in the energy installed and used for drying the water used in the traditional impregnation and coating processes;

-almost no contaminated exhaust gas;

easy storage and absence of bath preparation to obtain a suitable resin;

ease of preparation and use of resins and additives; the characteristics of the product to be obtained can be obtained only by powder mixing;

it is possible to stop and restart the production line with significantly less or even no loss of scrap or raw material, since the paper carrier is never wet and remains stable through the machine;

easy passage through the production line, since the carrier is always dry;

optimum longitudinal and transverse weight distribution, since it is obtained by the preparation of the component powder mixture outside the production line, which is dosed and distributed onto the support by means of a powder doser (optionally with a double dosing and dosing system) or a suitable applicator (both systems being able to be adjusted precisely);

problems associated with the difficulty of maintaining perfect mixing and adequate distribution of the various compounds with different specific gravities, are completely avoided, since they are used dry in powder form;

the surface wear of the spreading rollers, which continuously rub against particularly hard particles such as corundum, ceramic microspheres, etc., is completely avoided;

the powder feed system is a powder all-use system, thus eliminating the need for the recirculation systems currently used in pavers;

avoiding the problems associated with the ageing of the wet resin produced and with its catalysis, since only non-aged powders and dry mixtures are used;

the production line can even be stopped for a long time without the need for cleaning;

the problem of whitening the surfaces in the press is avoided, since the residual moisture percentage in the raw powder can be fully controlled upstream (opacifying or fogging effect);

the process of the invention, if applied to a production line of the direct printing type, enables to obtain high quality products very similar to those obtained with traditional paper impregnation and board pressing techniques, also with a structured surface,

the impregnated paper is immediately available for hot pressing of the laminate, so that the impregnation device can be integrated into the production line of the laminate.

The invention is further disclosed in the following non-limiting embodiments with reference to the accompanying drawings in which:

figure 1 is a schematic representation of the device used in a first embodiment of the process of the invention for manufacturing decorative papers and/or panels for floors or furniture facings, walls and the like;

figure 2 shows a variant of the device according to claim 1 used in a second embodiment of the method of the invention.

Figure 3 shows an example of an apparatus according to the invention suitable for impregnating a paper web on both sides in a single pass.

With reference to fig. 1, a device 1 for manufacturing decorative papers and/or panels for floors or furniture facings, walls and the like essentially comprises:

-feeding a handling line 2 of carriers 3 along a predetermined path P; the support 3 is a base paper support, optionally printed or otherwise decorated/coloured, optionally pre-treated or pre-impregnated, or any other kind of support, such as a board made of different materials (wood fibres or chips, plaster, etc.), which in turn optionally has been printed in a printing device (known and not shown); although in fig. 1 the carrier 3 is shown as a strip of material, it may obviously also be formed by a succession of elements, such as plates, sheets, etc.;

an (optional) preheating unit 4 of the support 3, wherein the support 3 passes and wherein the support 3 and in particular at least one first face 5 (e.g. top face) thereof is heated at a predetermined temperature;

-a preparation unit 6 of a powder composition, wherein a substantially dry or even anhydrous powder treatment composition as disclosed above is prepared;

an application group 7, in particular comprising a powder dosing device 8 connected to the preparation unit 6 to dispense the powder composition onto the support 3; the dosing means 8 are for example (but not necessarily) of the vibrating sieve type and allow the particles of the composition to fall by gravity onto the face 5 of the support 3; the dosing device 8 can be of other kinds, but in any case is generally capable of finely dosing and uniformly distributing the powder composition on the support 3 both in the longitudinal direction (direction of support feed) and in the transverse direction (direction perpendicular to the direction of support feed);

a heating unit 9 comprising, for example, an infrared lamp and/or a microwave oven or tunnel kiln, located downstream of dosing device 8 along path P, where the composition is heated to melt the polymeric component (resin) therein and trigger its crosslinking/polymerization reaction and form a polymeric coating 11 on face 5 of support 3;

possibly, a cooling unit 12 to harden the polymeric components of the treatment composition.

Optionally, the apparatus 1 comprises a plurality of dosing groups 7 (with respective powder dosing devices 8) and then respective heating units 9 (and optionally then respective cooling units 12) to sequentially apply respective polymeric compositions (preferably still of the kind disclosed above) having different compositions, formulations or properties.

For example, the device 1 also comprises, downstream of the first heating unit 9, along the path P, in succession:

a second powder application group to dose and dispense a second composition (similar or different to the previous one, but generally also formed by one or more melamine and/or phenolic resins, suitable catalysts and additives, such as corundum, glass microspheres, etc.) on the composition applied in the previous powder application group, to apply a further polymeric coating on the support to improve some of the surface characteristics of the product;

-a second heating unit, for example comprising an infrared lamp and/or a tunnel kiln or a microwave oven;

-a third powder application group to apply a third protective polymeric layer formed by a resin and a protective additive (such as glass microspheres, alpha-cellulose, etc.);

-a third heating unit, for example comprising infrared lamps and/or a tunnel kiln or a microwave oven;

in addition to or instead of the collection station of the treated carrier 3, such as a winder or a sheet cutting and stacking unit, etc., a finishing or decorating station 13 can be located at the end of the handling line 2 to apply a picture, print or finish to the treated carrier, for example by means of a release paper.

The operation of the apparatus 1 for carrying out the process of the invention is as follows.

The support 3, which as shown can be a paper support or a plate made of another material, is fed along the handling line 2 and passes below the dosing device 8 of the application group 7, possibly after passing through the (optional) preheating unit 4; the treatment composition prepared beforehand in the preparation unit 6 is dispensed on the face 5 of the support 3 by means of the dosing device 8.

The carrier 3 thus passes through a heating unit 9, where the polymeric component (resin) is at least partially melted and cross-linked/polymerized so that particles of other substances are embedded in the composition, and subsequently enters a cooling unit 12.

If the composition comprises the precursor reactants of the polymeric resin instead of one or more resins of this type which have been polycondensed, the heating step (carried out at a suitable temperature and pH) initiates in situ polymerization of the reactants and formation of the resin or corresponding polymeric resin directly on the support.

The opposite face 15 of the carrier 3 is then treated in a similar manner by means of further units and assemblies of the type disclosed above, or by passing the carrier 3 upside down through the same units and assemblies used for treating the face 5.

In the variant of fig. 2, in which details similar or identical to those already disclosed are indicated with the same numerals, the system 1 further comprises a handling line 2 to feed the carriers 3, the (optional) preheating unit 4, the powder composition preparation unit 6 and the application group 7 along a predetermined path P.

In this case, however, the application group 7 comprises a furnace 17 connected to the preparation unit 6, where the powder composition prepared in the preparation unit 6 is heated to melt its polymeric components and reach a fluid state; and application means 18 apt to apply and distribute a fluid composition (possibly embedding solid particles) on face 5 of support 3. The application device 18 is, for example, but not necessarily, a flat head, a roller system, a blade system, or the like.

The heating unit 9 for fixing the powder is therefore not required, since the powder polymeric components are melted upstream of the application device 18 and therefore before the composition is applied to the support 3.

Alternatively, the device 1 may also comprise a cooling unit 12.

Also in this variant, the device 1 can comprise a plurality of application groups 7 to apply, in succession, as disclosed above, respective polymeric components having different compositions, formulations or properties (still preferably of the type disclosed above)

For treating the faces 5, 15 of the support 3, two application devices 18 can be used which are placed on opposite faces of the support 3 and run on the respective faces 5, 15 of the support 3.

The process of the invention carried out with the apparatus 1 of fig. 2 is the same as that disclosed with reference to fig. 1, except that the powder polymeric components are now melted before the composition is applied to the support 3; the composition is thus applied to the support in the form of a fluid, formed from the molten polymer component embedding the other particulate material which may be present.

Referring to fig. 3, there is shown an apparatus of the present invention modified to enable coating and impregnation of both sides of a paper web in a single pass. The paper web 32 is fed into the apparatus from an unwinder 31, after a number of guide rolls to a preheating device 38 for preheating the carrier to facilitate powder binding by making a sticky paste-like state, passing a first powder spreading unit 35 where the powder material of the invention is spread on a first side. The web with the powder on the first side preferably passes under a first infrared heater 34 while being held by a vacuum belt 33 to avoid warping of the paper under the influence of heat and to allow the at least partially melted powder to start to penetrate into the web. The radiation of the infrared heater 34 melts and thereby secures the powder material to the web. In order to also coat the second side of the paper web, the paper web must be turned. This is achieved by passing it (in this case two) through the flipping station 36 with air cushions that do not contact the processing surface of the carrier. This is to avoid damage to the skin which may still be soft at this time. The carrier is then preheated by the second preheating device 38 and the second powder spreading unit 35 coats the second side of the web with powder material. The web passes through an infrared heater 34 and is supported therein by a vacuum belt 33. Finally the web is rewound on a rewinder 37 and optionally (not shown in fig. 3) sliced and stacked.

This type of device offers many opportunities. For example, on wood used for making boards for furniture or flooring, paper can be used for decorative coatings. The two layers may be different, for example one layer may be a decorative and wear resistant layer as a top surface of the floor and the other layer may simply be a material for gluing the paper to the carrier. Similar devices can be used to prepare impregnated backing layers for flooring, or for secondary decorative layers for furniture applications.

It can be seen that this type of device is easy to add, for example, to a continuous process line for manufacturing fibreboards. Whereby the decorative board can be manufactured in a single pass starting from the fibre pulp.

Another example of the use of the device is the manufacture of filter paper or kraft paper for low and high pressure applications.

It will be understood that further modifications and variations may be made to the system disclosed and illustrated herein without departing from the scope of the appended claims.

Label sheet

1 Dry impregnation System

2 Loading and unloading line

3 support to be treated

4 preheating unit

5 surface to be treated (first)

6 preparation unit

7 application group

8 quantitative feeding device

9 heating unit

11 fusion/fusion layer

12 cooling unit

13 finishing station

15 opposite surface

17 furnace

18 feeding device

31 uncoiler

32 paper web

33 vacuum belt

34 infrared heater

35 powder scattering unit

36 turning station (air cushion)

37 rewinding machine

38 preheating device

P carrier path

Claims (16)

1. Process for manufacturing decorative papers and/or boards, veneer foils, filter papers, kraft papers for low and high pressure use for floors or furniture facings or walls, comprising the following steps: preparing a treatment composition, applying the composition to a support; wherein the treatment composition is prepared in dry powder form and comprises a mixture of at least one powdered polymeric resin and/or powdered reactants susceptible to reacting and forming at least one polymeric resin; before or after the step of applying the composition to a support, the method comprising the step of heating the composition to at least partially melt the polymeric resin and/or to melt and polymerize/crosslink said reactants contained in the composition, the method being characterized in that the composition is a substantially dry solid composition, wherein said polymeric resin is one or more amino and/or phenolic resins or a mixture of the above resins.

2. A method according to claim 1, wherein the composition is applied dry to the support in powder form and heated after deposition onto the support.

3. A process according to claim 1 wherein the composition is first heated to melt and then applied to the support in the form of a fluid.

4. The method according to one of the preceding claims, wherein the polymeric resin is selected from urea resins, melamine resins, phenolic resins and combinations of these.

5. A process according to any one of the preceding claims 1 to 3, wherein the reactants liable to react and form at least one polymeric resin are selected from melamine, urea, phenol, formaldehyde and derivatives thereof and combinations of these.

6. A process according to any preceding claim wherein the composition further comprises one or more suitable catalysts in particulate or powder form.

7. The method according to any one of the preceding claims, wherein the composition comprises one or more solid substances selected from the group consisting of: corundum, glass or ceramic microspheres, alpha-cellulose, decorative materials, such as reflective, sparkling, opalescent, metallic lustre materials in the form of spots, particles or fibers.

8. The method according to any one of the preceding claims, wherein the powder polymeric resin and/or powder reactant has a particle size of less than about 1000 microns, preferably from about 0.1 microns to about 500 microns.

9. A method according to any preceding claim, including the step of preheating the carrier prior to applying the treatment composition.

10. A method according to any preceding claim, wherein both opposing faces of the support are treated with one or the respective treatment composition.

11. Device (1) for manufacturing decorative papers and/or panels for floors or furniture facings or walls, comprising a treatment composition preparation unit (6) and at least one application group (7) for applying the composition to a support (3); the device is characterized in that the preparation unit (6) facilitates the preparation of the composition in the form of a substantially dry powder, the device further comprising heating means (9, 17) downstream of the dosing means (8) or upstream of the dosing means (18) to melt and polymerize/crosslink the composition.

12. Device according to claim 11, wherein the application group (7) comprises dosing means (8) apt to spread the composition in powder form onto the support (3).

13. Apparatus according to claim 11, wherein the application group (7) comprises an application device (18) apt to spread the composition in fluid form onto the support and a furnace (17) with heating means.

14. Device according to one of claims 11 to 13, comprising two application groups (7) capable of acting on opposite sides of the support.

15. The apparatus of claim 14, further comprising means for inverting the carrier.

16. Apparatus according to claim 15, wherein the means for inverting the carrier comprise at least one non-contact air cushion (16).