EP2079877A1

EP2079877A1 - Processing method for a printing base for melaminated paper

Info

Publication number: EP2079877A1
Application number: EP07821663A
Authority: EP
Inventors: Ernst Heller; Nicolas Banyols; Olivier Pisarski
Original assignee: Papeteries du Leman
Current assignee: Papeteries du Leman
Priority date: 2006-10-26
Filing date: 2007-10-22
Publication date: 2009-07-22
Also published as: BRPI0716282A2; WO2008049811A1; CN101622400A; MC200104A1

Abstract

The invention relates to a method for processing a paper strip for producing a printing base for a melaminated paper that involves an application according to a low-pressure impregnation technique, and that comprises the following steps: e) producing a paper containing coarsely refined fibres, the paper containing pigments; f) applying a resin-based mixture on the upper surface of the paper to be printed; g) applying a resin-based layer on the lower surface of the paper to be applied against a panel; h) drying the paper; characterised in that the application steps (b) and (c) are carried out simultaneously and in that the mixtures applied on the upper and lower surfaces of the paper have different composition.

Description

PROCESSING PROCESS FOR MELAMINE PAPER PRINTING BASE

The invention relates to thin papers used in laminated or laminated decorations, as well as to their manufacturing processes.

The invention relates more precisely to the bases of printing of melamine papers, for the production of parquet or high-end furniture.

Depending on the desired applications and the manufacturing cost of the final product, two families of paper were developed on the market: "finished sheets" and "melamine papers".

Finished sheets are papers that are adhered to the desired support

(such as a panel) by means of a film of glue, placed continuously at the transformer, after making them at a paper mill and then decorated at a printer. If no additional step is implemented during their manufacturing process, this is called "Japanese paper", and their grammage (weight of the sheet per square meter in g m ^-2 ) is between 20 g m- ² and 50 g. m ^"2. This paper has a good internal cohesion and a high smoothness giving it printability and lacquering, but its transformation and collage are delicate as it tends to bulge (deformation from planarity).

It is also possible to implement an additional step, during which the paper is impregnated with a mixture of synthetic latex and thermosetting resins, either by means of a size-press, which is a double-sided coating device. roller, located on the paper machine, consisting of a pair of superimposed cylinders, whose arrangement can be horizontal or inclined (pre-impregnated cases, which then have a low warp but a higher cost and a less smoothed Japanese paper), either at the processor (in the case of post-impregnated manufacturing is higher because of the recovery of the process on different machines).

In a size-press, the paper passes through a soaking bath that forms between each cylinder and the sheet of paper. In this type of machine, it does not control the exact amount deposited on the paper and no more the amount that penetrates deep into the heart of the paper.

In addition, this machine having a single feed dipping bath, it is impossible to make differentiated deposits from one side to the other of the sheet of paper. In addition, even if one could achieve different product feeds, the fact that the paper completely through the soaking bath would make it impossible to deposit such differentiated deposits since the two products would mix with each other at the heart of the paper during soaking .

Nevertheless, the physical characteristics of the finished sheets thus obtained do not allow their use in all types of application. They are suitable for the manufacture of low-end furniture panels, vertical surfaces, etc. but their resistance to blows, abrasion, heat, liquids, light, or chemicals is low.

When such characteristics are necessary, for example when making parquet or quality furniture, melamine papers are preferably made, either by a low pressure technique or by a high pressure technique.

These melamine papers include: - a decorative sheet, a cover sheet, which gives the stack specific characteristics of strength, and protects the decorative sheet stains, abrasion and scratches.

Preferably, the cover sheet is composed of a cellulosic material, free of impurities and low opacity, which contains optionally mineral pigments to increase its resistance to abrasion and hardness. The pigment is chosen so that, following its impregnation, it induces neither appearance of color in the laminate, nor increased opacity, which would mask a pattern printed on the underlying decorative sheet.

The cover sheet generally has a basis weight of about 20 to 40 g. m ^"2 , which increases to 75 to 100 g / m ² after being impregnated.

During the low-pressure technique, the decorative sheet and the cover sheet are impregnated with a mixture of thermosetting resins and catalysts, and then applied to a panel (the back of which is usually applied a counterbalancing sheet for dimensionally stabilize the formed complex) by means of a low pressure press. The resin then diffuses in the stack of sheets, and allows their strong adhesion to the panel.

Unlike melamine papers, the finished sheets can not be used in a low (or high) pressure technique: their constituent material and their treatment do not allow their optimal impregnation with resins. That is why they are glued by means of a film of glue on the support panel which they must decorate. But this technical solution does not offer surface characteristics, scratch resistance, abrasion, sufficient to be used in the application of parquet floors, worktops or high-end furniture.

For example, EP 0 870 872 discloses a process for obtaining a thin paper of the finished sheet type, in which pigments (with the aid of a binder) are coated on the printing or lacquering surface of the paper , the face opposite the coating being impregnated with an impregnating resin. The absorption of the resin by the paper, however, amounts to only 5% to 30% by weight, based on the raw paper, the paper used in the manufacture of finished sheets not normally intended for to be impregnated. Otherwise, since no resin is present on its printing face, it has no particular dimensional stability.

The melamine paper, on the other hand, has a high dimensional stability and an increased resistance to abrasion and scratches compared to the finished sheets. This is why they are preferred in applications such as the production of parquet and high-end furniture.

During the high pressure technique, a cover sheet is also applied to a decorative sheet. But, unlike the low pressure technique, one or more sheets of kraft paper are placed under the decorative sheet. The complex thus formed is then impregnated with a melamine resin, before being placed in a press which applies a high pressure (and a high temperature), so as to obtain a "sandwich" of great density and great hardness. The cost of high pressure papers is 30% to 40% higher than that of low pressure laminates. They are used for example in the manufacture of work plans. Their mechanical performance, including their resistance to moisture or their temperature resistance, but also their resistance to abrasion and scratches, are much better.

This is why a great deal of research has been carried out with the aim of producing printing bases using a low-pressure, less expensive technique whose characteristics are similar to those of the printing bases obtained by the high-pressure technique, and whose grammage is low.

In this regard, the patent application WO 02/079571 describes for example a method of manufacturing a low pressure printing base, during which a composition comprising, on the upper surface, then optionally on the lower surface, is applied. a formaldehyde resin, an acrylic latex and a hardener. This process makes it possible to reduce the grammage of the paper weighing between 15 g. m ^"2 and 60 g. m ^{" 2} , as well as the amount of impregnated resin, while improving the mechanical characteristics of the printing base obtained. However, the method used requires two to three successive stages for the impregnation of the layers, which increases its time and cost of manufacture without improving the quality of printing compared to the state of the art.

Patent application WO 01/21892 for its part proposes a process for manufacturing paper for impregnation with synthetic resins, applicable to low and high pressure techniques, comprising the steps of impregnating the paper with a first mixture A based on resins, then, or simultaneously, to apply a second resin-based mixture B, preferably identical to the mixture A. Following a drying step, a third resin-based mixture C is then applied to at least one of the faces, preferably of the same composition as the mixture A. Thanks to the pretreatment step of this process, the paper obtained has a better quality of printing. However, the process requires many production steps, and therefore leads to an increase in its manufacturing cost.

An object of the invention is to provide a printing base for melamine paper having a low basis weight according to a low pressure technique.

Another object of the invention is to provide, in a single industrial operation, a printing base for melamine paper using a low pressure technique that combines greater dimensional stability than the state-of-the-art melamine papers when it is printed. and its transformation and superior print quality.

Another object of the invention is to provide a printing base for melamine paper according to a low pressure technique, the print quality of which is greater than that of the state-of-the-art melamine papers, so that get a larger print result, or reduce the level necessary inking with a print rendering equivalent to that of the state of the art, in order to reduce printing costs.

Another object of the invention is to provide a printing base for melamine paper according to a low pressure technique capable of being easily transformed, by increasing its mechanical strength and its cohesive strength.

Another object of the invention is to implement a low pressure manufacturing process of a printing base for melamine paper, to reduce the amount of impregnated resin during its processing.

Another object of the invention is to implement a low pressure manufacturing process of a melamine paper printing base, the production costs of which are reduced compared to known methods.

For this purpose, the invention proposes a paper tape processing method for the manufacture of a melamine paper printing base, for application to a low pressure impregnation technique, comprising the steps of: a) realizing a paper based on weakly refined fibers, the paper having pigments, b) coating a resin-based mixture on the upper surface of the paper, to be printed, c) coating a resin-based mixture on the lower surface of the paper, paper, intended to be applied against a panel, d) drying the paper, According to one characteristic of the invention, the coating steps (b) and (c) are simultaneous, and the coated on the top and bottom surfaces of the paper have a different composition.

According to another characteristic of the invention, the method comprises an additional step e) of treating at least one of the coated surfaces during steps (b) or (c) in soft calenders. In addition, steps (a) to (e) are advantageously performed directly on the same paper machine.

Other features, objects and advantages of the present invention will appear on reading the detailed description which follows, with reference to the appended drawings, given as non-limiting examples and in which:

FIG. 1 illustrates the impregnation of a sheet of paper by injection nozzles according to the invention,

- Figure 2 is a sectional view of Figure 1.

The laminate floors include, as we have seen, a decorative sheet, a cover sheet, a particle-based board (MDF (for Medium Density Fiber, medium density fiber), HDF (for High Density Fiber, fiber to high density), etc.) and a cover sheet. The invention relates to the improvement of the process for the treatment of papers used as printing bases (decorative sheets) of melamine papers, the covering sheet being applied, if necessary, by the transformer.

For this purpose, a support paper based on weakly refined fibers, comprising a mixture of 50 to 20% by weight of long fiber pulp (resinous) and 50 to 80% by weight of short fiber pulp ( Hardwood).

Long fibers are fibers of 3 to 5 mm, derived from softwoods such as pine, spruce, radiata pine or Douglas fir. Short fiber pasta, of the order of 1 to 2 mm, comes from eucalyptus, acacia, maple, birch or chestnut, for example.

The particular composition of this mixture is chosen to form a support particularly adapted to its impregnation at heart by resins which will be coated on the faces of the paper. Indeed, the percentage of short fibers (50 to 80%) makes it possible to improve the formation of the sheet while the percentage of long fibers (50 to 20%) form a canvas whose filling of the holes is made by means of short fibers, which creates a porosity of the support adapted to the filling of the resins heart. For example, if a paper comprising 70% of eucalyptus fibers per 30% of pine fibers is made, the basis weight of the backing paper could be between 40 and 43 gm ^-2 .

In the support paper are also present pigments known in the industry to give it a certain whiteness (to optimize the contrast of the decor) and sufficient opacity to prevent a pattern or defect of the board can be seen through the lens. paper thickness (transvision).

For example, titanium oxide TiO _{2 can be used} in a percentage ranging from 10% to 30% of the mass of the paper. A grade is chosen which gives the material good aging and light stability. According to the invention, inorganic pigments are also added to the paper, such as for example Kaolin, so as to further improve the opacity of the paper (from 0% to 20% of the weight of the dry paper base, according to the pigments). The mineral pigments are indeed excellent inter-fiber filling materials. The addition of these pigments combined with a low degree of refining of the fibrous mixture leads to high porosity levels for the base paper base (eg gurley porosity <20 s).

It is also possible to add at this stage additives improving the resistance of the material, such as a polyamide epichlorohydrin resin (PAE), at a rate of 0.1% to 1.5% of the mass of the dry paper base, which is an agent known in paper mill for its characteristics of resistance in the wet state.

Preferably, during the manufacturing process, the pH of the fibrous suspension is maintained close to the neutral pH in the wet part of the machine, in order to promote the crosslinking of the impregnated resins. Thus, all the steps of the manufacturing process are carried out in a weakly basic or acidic medium corresponding to a pH of between 6.5 and 7.5. This is to increase the rate of crosslinking of the resins, an important element of the process, since it provides for incorporating into the paper a maximum of resin at the top of the paper machine and it is important that the resin stored in the paper is fully reticulated when the paper web comes out of the paper machine.

However, it has been found that the crosslinking of the resins is faster in a substantially neutral medium. The resins being relatively basic (pH between 7.7 and 8.5), it is therefore important that the bath of the pulp is at a pH between 6.5 and 7.5 to neutralize the resins and thus improve their rate of crosslinking.

According to the method of the invention, a differential coating of the paper formed directly on the paper machine is implemented by means of a "film-press" or "film-sizer". This differential coating consists of depositing simultaneously on the upper surface (which corresponds to the surface that will be in contact with the cover sheet) and on the lower surface

(which will be in contact with the panel) paper two different compositions.

The film-press or film-sizer is a double-sided coating device using worms 3a, 3b called "pencils" or blades for driving in a controlled manner the coating composition on pressure rollers 2a,

2b sleeping.

It comprises, as illustrated in the accompanying figures, two pressure rollers 2a and 2b, two worm 3a and 3b and two discharge bins 4a and 4b, arranged symmetrically with respect to the plane of the paper 1. Their longitudinal axes extend parallel to each other and perpendicular to the direction of travel 10 of the paper 1.

The roll 2a, placed on one side of the paper 1, makes it possible, by compressing the paper 1 against the second roll 2b, to drive it in the direction and the direction of travel 10. Each worm 3a, 3b is in contact with the roller 2a, 2b corresponding. The principle of volumetric deposition related to the diameter of the spirally wound metal wires around the roller 3a-3b makes it possible to finely control the volume of each deposited composition. Furthermore, the recovery bins 4a and 4b are disposed respectively under the worm 3a and 3b to recover and recycle each excess resin mixture. For this, each tray 4a, 4b is connected to a respective recycling circuit, in order to take into account separately the composition collected on each side of the paper.

The composition of the layer applied to the lower surface, whose grammage represents between 20% and 40% of the final basis weight of the paper, is preferably composed of:

at least one mineral pigment, such as Kaolin, in a proportion of from 0% to 40% of the composition by dry weight, preferably 28%.

It thus makes it possible to maintain a certain porosity to the finished paper, which will favor the quality of the subsequent impregnation

a thermosetting resin which may be either a urea resin or formaldehyde resin, in a proportion of 30% to 80% of the composition by dry weight, preferably 36%, or an acrylic resin, melamine, aldehyde, modified urea formic acid, or a resin not releasing formaldehyde during its crosslinking and drying.

These resins can be chosen from the various Kaurit ranges offered by BASF. The resins of the lower layer are intended to provide resistance to the delamination of the paper when it is adhered thanks to the diffusion of the resins on the support panel on which the paper is applied, by increasing the internal cohesion of the material, and by stiffening.

a synthetic latex, in a proportion of 20% to 50% of the composition by dry weight, preferably 36%, such as a styrene-acrylic latex with a glass transition temperature Tg greater than 20-25 °. This latex is indeed self-crosslinking, and leads, unlike the resin, a flexibility to the material, to avoid making it too brittle.

a catalyst of the resin, in a proportion of 0.2% to 5% of the mass of resin used. The catalyst chosen depends, of course, on the thermosetting resin composing the layer.

Thus, for a urea-formaldehyde resin, a hardener based on inorganic salts will be chosen as the catalyst, whereas if the choice of resin has been based on an acrylic, melamine, aldehyde, formic or modified urea resin, the catalyst may be be paratoluene sulfonic acid (ATPS).

For the preferred percentages mentioned above, the bottom layer then has a basis weight of 27% of the basis weight of the decorative sheet (i.e., base paper).

With this specific composition of the lower layer of the paper, a paper is obtained whose dimensional stability is significantly improved. The resin mixture indeed coats the fibers thus preventing water from entering the heart of the fibrous network. The catalyst used promotes this hydrophobicity. It plays a role in insolubilizing the thermosetting resin by increasing the water resistance of the treated paper. Thus, during its printing and processing, the paper does not undergo expansion or shrinkage despite changes in the degree of humidity, which significantly reduces the scrap rate at the end of production. Indeed, during the final operation of slicing the melamine board (that is to say the support on which the impregnated melamine paper and counterbalance sheet have been glued by pressure on the press), if the paper is shrunk or stretched during processing or printing, the cut was not made on the cut line preprinted on the paper, but outside, resulting in its immediate disposal. In comparison, according to the MUTEK test which represents the stability in% elongation in a humid medium, the level of dimensional stability of a paper obtained according to the process of the invention is 0.5%, whereas with a standard paper, the level of stability is 2.5% to 3%.

The composition of the layer applied on the upper surface, which is deposited at a rate of 2 g. m ^"2 to 10 gm ^-2" on the paper, consists of:

at least one mineral pigment, such as Kaolin, in a proportion of 60% to 95% of the composition by dry weight, preferably 88%. an acrylic, melamine, aldehyde, formic, urea resin modified at a level of from 5% to 40% of the composition by dry weight, preferably 12%, chosen from the Kaurit range proposed by BASF, or a resin that does not release formaldehyde during its crosslinking and drying. This resin serves as a binder to the pigmentary part of the layer, and is compatible with the impregnating resins used during the processing.

a catalyst of the resin, in a proportion of 0.2% to 1% of the mass of resin used, such as paratoluene sulphonic acid (ATPS).

This specific composition of the top layer deposited on one side of the paper, face intended for printing increases the print quality of the final paper.

The particular nature of this highly pigmented layer makes it possible to achieve high levels of smoothness, and thus an excellent surface state, as well as very good printing results.

Indeed, the presence of inorganic pigments such as Kaolin, the size and shape of the particles make a pigment particularly suitable for this application, in combination with a subsequent calendering step, give the upper layer a greater smoothness. The contact between the print head and the paper then becomes more regular, which makes it possible to obtain an image of greater optical density, or with a more regular contrast. At the same amount of ink, the print result is better; and with equal print quality, the amount of ink used can be reduced, resulting in saving printing costs.

Other pigments can of course be used, such as titanium dioxide (TiO ₂ ) or calcium carbonate (CaCOs).

A final paper having a basis weight of 56 g is obtained. m ^"2 and 60 g m ^-2 .

For the preferred mass percentages mentioned in the description of the preferred embodiment, consisting of the base paper coated with the above-mentioned lower and top layers, the respective basis weights of the layers are 40-43 g. m ² , 12 g, m ² and 4 g. m ² to 5 g m ^-2 .

Moreover, thanks to a specific composition of the lower and upper layers of the paper, the dimensional stability of the paper is superior to the products of the state of the art.

In fact, the resins composing the lower layer penetrate the core of the paper by their nature while the resin of the upper layer associated with the pigments remains mostly on the surface, thus allowing the inks during printing not to be diluted in the paper. paper thickness and therefore keep a sharp impression sharpness.

This is followed by a drying step of the paper thus coated, followed by a surface treatment in soft calenders. A soft shell is a shell consisting of rolls covered with elastic materials on the one hand, and rollers having a hard surface on the other hand. By passing the paper between a hard roll and a soft roll, covered for example with a polyurethane coating, it allows to apply different calendering pressures on both sides of the paper, while maintaining a high opacity of the paper . These steps also take place on the paper machine. Preferably, the surface treatment is applied mainly to the upper layer in order to improve the printing characteristics, especially its smoothness. During the operation, according to the invention, it is possible to obtain Bekk smooths greater than 300 seconds.

In the Bekk measurement process, an air jet is applied perpendicular to a sheet of paper placed on a solid support. The Bekk measurement measures the surface air leakage of the paper, which gives a measure of the smoothness of the paper sheet. In this type of measurement, large coefficients are representative of a very high level of smoothness. In the type of application concerned by the invention, a coefficient of 300 is representative of a high quality smoothness.

Finally, the paper thus obtained is applied to the desired panel, such as a floorboard or parquet, behind which is usually placed a counter-balancing sheet, to stabilize the dimensionally complex complex thus formed.

After impregnation with known resins, a pressure of the order of 2.1 to 2.8 MPa is then applied by means of a low pressure press, the stack comprising the decorative paper, the cover sheet, the panel and the counterbalancing sheet, at a temperature between 105 ⁰ C and 225 ⁰ C, for a period of time ranging from 30 seconds to 40 seconds. During this step, diffusion of the impregnated resin into the stack diffuses and renders the cover sheet transparent.

By coating specific compositions on the upper and lower surfaces of the paper, the amount of impregnating resins (used to impregnate the cover sheet and the printing base obtained by the process) required for paper processing can be reduced. , during the low pressure technique. This is made possible by the fact that, by means of the film-press at the beginning of the process, a large quantity of resin coming from the lower layer is already present in the paper structure, which will make it possible to reduce the amount of resin that will be necessary and even possible to penetrate the paper during the final impregnation operation after printing.

In addition, as a direct result of reducing the amount of impregnating resins, the weight of the final melamine paper obtained is proportionally reduced. And the lowering of the grammage and the amount of impregnated resin mechanically induces a proportional decrease in basis weight and impregnation at the level of the counter-balancing sheet.

Indeed, when making the laminate floor, the counterbalancing sheet must necessarily have a weight equal to that of the top layer applied to the panel, to avoid any deformation of the paper and the panel, such as the bulge.

Those skilled in the art will appreciate, in comparison with the methods of the state of the art, a method making it possible to produce in a single industrial operation a printing base for melamine paper using a low pressure technique that combines superior dimensional stability. to that of state-of-the-art melamine papers during printing and processing and superior print quality.

Such a method according to the invention combines the particular advantages of different products that the state of the art did not allow to gather on the same product in a single step.

In addition, those skilled in the art will appreciate a low pressure manufacturing process of a melamine paper printing base, whose production costs are reduced compared to known methods since all operations are done during a single industrial process on a machine single paper, and not in batch processes involving stakeholders located in different locations with outages, transport, intermediate losses and buffer storage.

The invention also relates to paper strips for the production of a printing base, obtained according to the method of the invention and such that, on their upper face, is coated a resin-based mixture and that, on their underside, is coated a resin-based mixture different from the first mixture. The resin-based mixture coated on the bottom surface comprises:

- 30% to 80% of resin,

- 20% to 50% latex,

0.2% to 5% of the mass of resin in catalyst, and

- 0% to 40% pigment, the composition of the mixture by dry weight.

The resin-based mixture coated on the upper surface comprises at least one resin, a pigment, and a resin catalyst.

The resin may be an acrylic resin, melamine, aldehyde, formic, urea modified as described above and the resin catalyst will be paratoluene sulfonic acid.

In another variant, the resin may be a resin not releasing formaldehyde during its crosslinking and drying.

The resin-based mixture coated on the upper surface may comprise according to the invention: 5% to 40% of resin,

0.2% to 1% of the mass of resin in catalyst, and

60% to 95% of pigment, of the composition of the mixture by dry weight. The invention also relates to the floor elements comprising paper strips, as described above, and may further comprise a cover sheet and a counterbalancing sheet.

Claims

A paper web processing method for the manufacture of a melamine paper printing base for application to a low pressure impregnation technique, comprising the steps of: a) producing a paper made from fibers poorly refined, the paper containing pigments, b) coating a resin-based mixture on the upper surface of the paper, to be printed, c) coating a resin-based mixture on the lower surface of the paper, to be applied against a panel, d) drying the paper, characterized in that the coating steps (b) and (c) are simultaneous, and in that the mixtures coated on the upper and lower surfaces of the paper have a different composition.

2 A method of treatment for paper web according to claim 1, characterized in that it comprises an additional step e) of treating at least one of the coated surfaces during steps (b) or (c) in soft calenders.

3 processing method for paper web according to the preceding claim, characterized in that the steps (a) to (e) are performed directly on the same paper machine.

4 A process for treating a paper web according to any one of the preceding claims, characterized in that a fibrous support comprising a mixture of 20 to 50% by weight of pulp is used to manufacture the paper of step a). long fibers derived from softwood and 50 to 80% by weight of short fiber pulp from hardwoods. Paper strip processing method according to one of Claims 2 to 4, characterized in that all of the steps a) to e) are carried out in a weakly basic or acidic medium corresponding to a pH of between 6.5 and 7.5.

The paper strip processing method according to one of the preceding claims, characterized in that the resin-based mixture coated on the lower surface further comprises latex.

7 processing method for paper tape according to the preceding claim, characterized in that the latex is a self-crosslinking acrylic latex.

The paper web processing method according to one of the preceding claims, characterized in that the resin-based mixture coated on the lower surface further comprises at least one pigment.

9 processing method for paper web according to the preceding claim, characterized in that the pigment is a mineral pigment.

Paper strip processing method according to the preceding claim, characterized in that the inorganic pigment is Kaolin.

A paper strip processing method according to one of the preceding claims, characterized in that the resin-based mixture coated on the lower surface comprises a thermosetting resin.

A paper web processing method according to claim 11, characterized in that the resin-based mixture coated on the lower surface comprises a urea-formaldehyde resin. 13. Paper strip processing method according to claim 11, characterized in that the resin-based mixture coated on the lower surface comprises at least one acrylic resin, melamine, aldehyde, modified urea formate.

Paper strip processing method according to claim 11, characterized in that the resin-based mixture coated on the lower surface comprises a resin which does not release formaldehyde during its crosslinking and drying.

The paper web processing method according to one of the preceding claims, characterized in that the resin-based mixture coated on the lower surface further comprises a resin catalyst.

A paper strip processing method according to the combination of claims 12 and 15, characterized in that the resin catalyst is a hardener based on inorganic salts.

A process for treating paper web according to the combination of claims 13 and 15, characterized in that the resin catalyst is paratoluene sulfonic acid (ATPS).

The paper web processing method according to one of the preceding claims, characterized in that the resin-based mixture coated on the upper surface further comprises a pigment.

19 Process of treatment for paper tape according to the preceding claim, characterized in that the pigment is a mineral pigment.

Processing method for paper tape according to the claim preceding, characterized in that the mineral pigment is Kaolin.

The paper web processing method according to one of the preceding claims, characterized in that the resin-based mixture coated on the upper surface comprises at least one acrylic resin, melamine, aldehyde, formic, modified urea.

Process for treating paper web according to the preceding claim, characterized in that the resin-based mixture coated on the upper surface further comprises a catalyst, said catalyst being paratoluene sulfonic acid.

Paper strip processing method according to one of claims 1 to 20, characterized in that the resin-based mixture coated on the upper surface comprises a resin which does not release formaldehyde during its crosslinking and drying.

24 Paper tape for the production of a printing base, characterized in that a resin-based mixture is coated on its upper surface and a resin-based mixture is coated on its underside of the first mixture.

Paper strip according to the preceding claim, characterized in that the resin-based mixture coated on the lower surface comprises at least one resin, a latex, a resin catalyst, and a pigment.

Paper strip according to one of Claims 24 or 25, characterized in that the resin-based mixture coated on the lower surface comprises: - 30% to 80% resin, - 20% to 50% latex,

0.2% to 5% of the mass of resin in catalyst, and

- 0% to 40% pigment, the composition of the mixture by dry weight.

Paper strip according to Claim 26, characterized in that the resin is a urea resin, formaldehyde resin and the resin catalyst is a hardener based on inorganic salts.

Paper strip according to Claim 26, characterized in that the resin is an acrylic, melamine, aldehyde, formic, modified urea resin and the resin catalyst is paratoluene sulphonic acid.

Paper strip according to Claim 26, characterized in that the resin is a resin which does not release formaldehyde during its crosslinking and drying.

Paper web according to one of claims 25 to 29, characterized in that the resin-based mixture coated on the lower surface comprises a mineral pigment.

31 Paper tape according to the preceding claim, characterized in that the mineral pigment is Kaolin.

32 Paper tape according to one of claims 25 to 31, characterized in that the latex is a self-crosslinking acrylic latex.

Paper web according to one of claims 24 to 32, characterized in that the resin-based mixture coated on the upper surface comprises at least one resin, a pigment, and a resin catalyst. Paper web according to claim 33, characterized in that the resin is an acrylic resin, melamine, aldehyde, modified urea formate and the resin catalyst is paratoluene sulfonic acid.

Paper strip according to Claim 33, characterized in that the resin is a resin which does not release formaldehyde during its crosslinking and drying.

Paper strip according to claim 33, characterized in that the resin-based mixture coated on the upper surface comprises:

- 5% to 40% of resin,

0.2% to 1% of the mass of resin in catalyst, and

60% to 95% of pigment, of the composition of the mixture by dry weight.

37 Paper tape according to one of claims 33 to 36, characterized in that the pigment is a mineral pigment.

38 Paper tape according to the preceding claim, characterized in that the pigment is Kaolin.

39 Paper tape according to one of claims 24 to 38, characterized in that it is obtained by means of a treatment method according to one of claims 1 to 23.

40 Parquet element, characterized in that it comprises a strip of paper according to one of claims 24 to 39.

41 parquet element according to the preceding claim, characterized in that it further comprises a cover sheet and a counterbalancing sheet.